WO1996016348A1

WO1996016348A1 - Liquid crystal display device

Info

Publication number: WO1996016348A1
Application number: PCT/JP1995/002332
Authority: WO
Inventors: Yasuo Mori
Original assignee: Hitachi Ltd.
Priority date: 1994-11-24
Filing date: 1995-11-15
Publication date: 1996-05-30

Abstract

A liquid crystal device in which a liquid crystal display element illuminated with a planar luminous flux emitted through a transparent guide plate from a cold cathode fluorescent lamp placed along one of the side edges of the transparent guide plate. The liquid crystal display device includes a collimator lens disposed on a light incidence surface of the guide plate to improve directivity of the luminous flux from the cold cathode lamp before it enters the guide plate, and a prism sheet for directing the luminous flux from the guide plate toward the liquid crystal element to a direction nearly normal to the upper surface of the guide plate. Hollow beads are dispersed in the guide plate to improve the efficiency of use of light from the fluorescent lamp and provide uniform brightness so as to obtain bright and uniform display.

Description

Specification

[Title of Invention]

Liquid crystal display

〔Technical field〕

INDUSTRIAL APPLICABILITY The present invention can be used for various types of liquid crystal display devices such as a simple matrix type and an active matrix type, and is particularly effective when applied to a surface light source device used as a backlight which is an illuminating means of the liquid crystal display device. .

(Background technology)

With the dawn of the Mobile's Combining era, there is a demand for thinner, lighter, and lower power consumption display devices to achieve practically portable performance.

In recent years, a so-called liquid crystal display device has been widely used as such a thin, low-power display device.

The liquid crystal display device has an illumination device called a backlight installed below the liquid crystal display element, and images formed with the illumination light from the backlight and characters formed on the liquid crystal display element are used to visualize numbers. .

The backlight is a light guide plate formed of a transparent substrate for transmitting light in a plane, a cold cathode fluorescent lamp installed along at least one side edge of the light guide plate, an upper surface of the light guide plate, and a liquid crystal display element. It is mainly composed of a prism sheet inserted between them, and a reflection sheet installed or formed below the light guide plate.

FIG. 1 is an exploded perspective view illustrating an example of the overall configuration of the liquid crystal display device, wherein 1 is a liquid crystal display element, 2 is a backlight, 3 is a light guide plate, 4 is a cold cathode fluorescent lamp, and 5 is a lamp reflection sheet. , 8 is a prism sheet, 9 is a reflection sheet, 10 is a diffusion sheet, 13 is an upper frame, 14 is a spacer, 15 is a printed circuit board, 16 is a light shielding frame, 16 is a light shielding frame, 17 is an intermediate frame, 18 Is a lower frame, and 19 is a lamp cover.

In the same figure, a liquid crystal display element 1 is integrated with a printed circuit board 15 on which electronic components such as a drive IC are mounted, and a backlight 2 is laminated on a lower part of the liquid crystal display element 1 to be attached to an intermediate frame 17. Is fixed between the upper frame 13 and the lower frame 18.

The knock light 2 has a large area covering at least the effective area of the liquid crystal display element 1. A light guide plate 3 having a beam, a reflection sheet 9 provided below the light guide plate 3, a diffusion sheet 10 provided on the upper surface of the light guide plate 3, and provided between the diffusion sheet 10 and the liquid crystal display element 1. And a cold cathode fluorescent lamp 4, a lamp reflection sheet 5, and a lamp cover 19 disposed along one edge of the light guide plate 3. A spacer 14 is interposed between the liquid crystal display element 1 and the upper frame 13, and the light from the backlight 2 is interposed between the liquid crystal display element 1 and the backlight 2. A light-shielding frame 16 is installed to prevent the element 1 from leaking out of the effective area.

In such a structure, the effective area of the liquid crystal display element 1 is illuminated with the illumination light from the backlight 2, and an image, characters, and numerals formed on the liquid crystal display element 1 are visually displayed.

FIG. 2 is a cross-sectional view of a main part for explaining the structure of a backlight in a conventional liquid crystal display device. 1 is a liquid crystal display element, 2 is a backlight, 3 is a light guide plate, 3 a is a light reflection treated surface, 4 is a cold cathode fluorescent lamp, 4a is a cold cathode fluorescent lamp supply cable, 5 is a lamp reflection sheet, 8 is a prism sheet, 9 is a reflection sheet, 10 is a diffusion sheet, 13 is an upper frame, and 15 is an upper frame. Is a printed circuit board, 15a is a drive IC mounted on the printed circuit board, 17 is an intermediate frame, and 18 is a lower frame.

In the figure, a backlight (illumination light source) 2 is constituted by a cold cathode fluorescent lamp 4, a lamp reflection sheet 5, a reflection sheet 9, a light guide plate 3, a diffusion sheet 10 and a prism sheet 8.

A liquid crystal display element 1 is stacked above a backlight 2 which is an illumination light source, and is integrated with an upper frame 13 and a lower frame 18 together with a printed circuit board 15 on which a drive IC 15a is mounted. Is configured.

All light rays entering the light entrance surface of the light guide plate 3 from the cold cathode fluorescent lamp 4 enter the light guide plate 3 at a refraction angle of 42 ° or less with respect to the light entrance surface, and are indicated by arrows in the figure. As described above, the light guide した δΤ® formed with the processing surface 3a that avoids the regular reflection by the upper surface of the light guide plate and the total reflection such as a prism surface (prism array) or a dot-line printed pattern or a rough surface. While repeating reflection and scattering, the light propagates through the light guide plate 3 and is directed toward the liquid crystal display element 1 to illuminate the liquid crystal display element 1 from behind. As described above, the backlight used in the liquid crystal display device has a surface formed by propagating light from the cold-cathode tube provided along the side edge of the light guide plate made of a transparent plate, preferably a resin plate, to the light guide plate. It is distributed in a shape.

In recent years, it is necessary to reduce the thickness and weight of liquid crystal display devices and to reduce the thickness and weight of liquid crystal display devices. .

In particular, to improve the luminance efficiency for the purpose of reducing power consumption, the S-D9 APPLICATIONS DIGEST (S [D94 APPLICATIONS DIGEST]) As shown on pages 10 to 13, the collimator is installed in the surface light source device. Is being provided.

Fig. 3 is a schematic sectional view showing a partial structure of a backlight having a collimated light.

As shown in the figure, a collimator 20 is provided along the end face of the light guide plate 3, a lamp reflection sheet 5 is attached to an end of the collimator 20, and the end face of the collimator 20 and the lamp reflection are provided. The cold cathode fluorescent lamp 4 is provided in the space formed by the sheet 5. The light-reflection-treated surface 3a (the prism array in the figure) is provided on the back surface of the light guide plate 3, that is, the surface opposite to the liquid crystal display element, but may be a dot or line-shaped print pattern. .

In the backlight having such a structure, the light generated from the cold cathode fluorescent lamp 4 enters the collimator 20 from the collimator incident light surface 2 Ob, for example, enters the collimator at an incident angle of 90 °. ^ Incident on the surface 2 Ob enters the collimator at a refraction angle of 42 °. When the collimator enters the collimator, for example, when the inclination angle of the collimator slope 20a is 6 °, the angle formed with the horizontal direction in the figure by one internal reflection at the slope 20a of the collimator 20 is as follows. The angle becomes 30 °, and the angle between the horizontal direction in the figure and the two internal reflections is 18. Since all the rays that are internally reflected by the slope 20a of the collimator 20 change their traveling direction to a direction closer to horizontal, all the rays that enter the light-entering surface 3b of the light guide plate 3 The directivity of the luminous flux is increased, and most of the luminous flux having the increased directivity is a prism array (hereinafter, referred to as 3a, which is a light reflection processing surface 3a disposed on the Tffi of the light guide plate 3). Emitted to the upper surface through specular reflection by the slope Therefore, even if the light amount of all the luminous flux is the same, there is an effect that the luminance is improved by the higher directivity.

However, such a backlight enhances the directivity of light by internal reflection in the collimator 20, so that the cross-sectional shape of the collimator 20 becomes wider and smaller than the diameter of the cold cathode fluorescent lamp 4. However, it is necessary to use the light guide plate 3 having a considerably large thickness. This is disadvantageous in reducing the thickness and weight of the backlight.

In addition, since the collimator 20 is installed between the light guide plate 3 and the cold cathode fluorescent lamp 4, the size of the cold cathode fluorescent lamp installation part of the knock light becomes large, and the non-light emitting area of the knock light becomes large. This has the disadvantage that the size in the plane direction increases due to the increase, and the so-called frame width of the liquid crystal display device becomes wide.

Furthermore, since the collimating action of the collimator 20 has no effect on the longitudinal direction of the cold cathode fluorescent lamp 4, the light diffused in the longitudinal direction of the cold cathode fluorescent lamp 4 is still effective for the liquid crystal display device. There was a problem that it could not be used as an illuminating light.

[Disclosure of the Invention]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and has as its object to provide a liquid crystal display having a backlight capable of achieving low power consumption while satisfying the demand for a thin and light weight. It is intended to provide a device. In order to achieve the above object, the present invention provides a liquid crystal display device having a backlight in which a cold cathode fluorescent lamp is installed near a side end surface of a light guide plate, wherein the side end surface of the light guide plate, the cold cathode fluorescent lamp, A collimator lens sheet is provided between them.

To achieve the above object, according to the present invention, there is provided a liquid crystal display device having a backlight in which a cold cathode fluorescent lamp is installed near a side end surface of a light guide plate, wherein the side end surface of the light guide plate, the cold cathode fluorescent lamp, A collimator lens sheet is provided between the light guide plates, and a light reflection pattern is formed on the light guide plate to make the luminance distribution uniform.

Further, in order to achieve the above object, according to the present invention, there is provided a liquid crystal display device having a backlight in which a cold cathode fluorescent lamp is installed near a side end face of the isoluminous plate, A collimator lens sheet is provided between the side end surface of the plate and the cold cathode fluorescent lamp, and a light reflection pattern is formed on the lower surface of the light guide plate to make the luminance distribution uniform. A prism sheet having a prism surface on the lower surface for controlling the direction of a light beam emitted from the upper surface of the light guide plate is provided.

To achieve the above object, according to the present invention, there is provided a liquid crystal display device having a backlight in which a cold cathode fluorescent lamp is installed near a side end surface of a light guide plate, wherein the side end surface of the light guide plate and the cold cathode fluorescent lamp are provided. A collimator lens sheet is provided between the two, and a light reflection pattern is formed on the lower surface of the light guide plate to make the luminance distribution uniform, and the direction of the light beam emitted from the upper surface of the light guide plate is formed above the light guide plate. A prism sheet having a prism surface on the lower surface for control is provided, and hollow beads are mixed in the light guide plate.

The collimating overnight lens sheet, the light reflection pattern, and the light guide plate mixed with hollow beads are not limited to those used in combination with each other, and may be used alone and in combination with a conventional backlight structural member. .

Further, a diffusion plate may be interposed between the breath sheet and the light guide plate as necessary.

In the backlight of the present invention, the light generated from the cold cathode fluorescent lamp is collimated by a thin collimator lens sheet, which is different from the case of using the internal reflection type collimator as shown in FIG. In addition, a light guide having substantially the same thickness as the diameter of the cold cathode fluorescent lamp can be used, so that the brightness can be improved and the power consumption can be reduced without hindering the reduction in thickness and weight. In addition, since the thickness of the collimator lens sheet is small, there is no unnecessary expansion of the non-light-emitting area, and the width of the frame of the liquid crystal display device does not increase. In addition, by forming a light reflection processing surface (prism array or reflection pattern) on the lower surface of the light guide plate, light from the cold cathode fluorescent lamp is emitted from the upper surface of the light guide plate and the luminance distribution of the illumination light is made uniform. be able to.

Furthermore, if the direction of maximum luminous intensity when the light beam whose directivity is enhanced by the collimator lens sheet exits from the upper surface of the light guide plate is inclined with respect to the normal direction on the upper surface of the light guide plate, the light guide plate The lower surface for controlling the direction of the luminous flux emitted from the upper surface is provided with a prism sheet on the lower surface. The proportion of the luminous flux that can be effectively transmitted through the display element increases, and the light use efficiency is improved, so that low power consumption can be achieved.

Since the hollow beads are mixed in the light guide plate, the light flux propagating in the light guide plate can be diffused even in a region where the frequency of hitting the light reflection pattern is small. Can be suppressed.

[Brief description of drawings]

FIG. 1 is an exploded perspective view illustrating an overall configuration example of a liquid crystal display device, FIG. 2 is a cross-sectional view of a main part illustrating a structure of a backlight in a conventional liquid crystal display device, and FIG.

3 is a schematic cross-sectional view showing a partial structure of a backlight having a collimator, FIG. 4 is a schematic diagram of a main part illustrating an embodiment of a liquid crystal display device according to the present invention, FIG. 5 is FIG. Fig. 6 is a partially broken plan view illustrating the installation state of the collimating lens sheet constituting the backlight in Fig. 4. Fig. 6 is a description of the first example of the collimating lens sheet constituting the backlight in the present invention. FIG. 7 is an explanatory view of a second example of a collimator lens sheet constituting the knock light according to the present invention, and FIG. 8 is a second view of a collimating lens sheet constituting the backlight according to the present invention. Fig. 9 is an explanatory view of three examples, Fig. 9 is a partially broken plan view showing another installation state of the collimated overnight lens sheet constituting the backlight in Fig. 4, Fig. 10 is Collimator lens sheet constituting backlight in the present invention Illustration of a fourth example, F

1 g.11 is an explanatory view of a fifth example of a collimating lens sheet constituting a backlight according to the present invention, and FIG. 12 is a sixth example of a collimating lens sheet constituting a backlight according to the present invention. FIG. 13 is an explanatory view of a seventh example of a collimating lens sheet constituting a backlight according to the present invention. FIG. 14 is a collimator lens constituting a backlight according to the present invention. FIG. 15 is an explanatory view of an eighth example of the sheet, FIG. 15 is an explanatory view of a ninth example of the collimating overnight lens sheet constituting the backlight of the present invention, and FIG. 16 is a backlight of the present invention. FIG. 17 is an explanatory view of a tenth example of a collimator lens sheet to be constituted, FIG. 17 is a schematic diagram of a main part illustrating another embodiment of the liquid crystal display device according to the present invention, and FIG. Explanatory drawing of a first example of a collimated lens sheet constituting a backlight in FIG. 19 is an explanatory view of a first or second example of the collimator lens sheet constituting the backlight according to the present invention, and FIG. 20 is a first example of a collimator lens sheet constituting the backlight according to the present invention. FIG. 21 is an explanatory view of three examples, FIG. 21 is an explanatory view of a 14th example of a collimated overnight lens sheet constituting the backlight of the present invention, and FIG. 22 is a backlight of the present invention. Explanatory drawing of the 15th example of a collimated overnight lens sheet, Fig.

Reference numeral 23 denotes the first sixteenth lens sheet of the collimating lens constituting the backlight in the present invention. FIG. 24 is an explanatory diagram of an example, FIG. 24 is a schematic diagram of a main part illustrating still another embodiment of the liquid crystal display device according to the present invention, and FIG. FIG. 26 is an explanatory diagram of an angular distribution and an emission angle distribution of the luminous intensity of a brilliance sheet emitted light beam. FIG. 26 is a schematic diagram illustrating a cross-sectional shape of a bism sheet having a prism surface on a lower surface used in the present embodiment. 27 is a layout diagram of the light guide plate and the prism sheet illustrating the operation of the prism sheet having the lower surface in this embodiment, and FIG. 28 is another sectional shape of the prism sheet having the lower surface of the prism surface. FIG. 29 is an explanatory diagram of an example, FIG. 29 is a schematic diagram of a main part illustrating still another embodiment of the liquid crystal display device according to the present invention, and FIG. 30 is an A—A Di of FIG. FIG. 31 is a cross-sectional schematic view taken along the line Fig. 31 is a cross-sectional view of a principal part illustrating the shape of the prism surface of the bism sheet in FIG. g. 32 is an explanatory diagram of the relationship between the direction of the bristles groove of the three prism sheets in the present embodiment, and FIG. 33 is a diagram showing the prism groove shape of the prism sheet installed on the liquid crystal display element side in the present embodiment. FIG. 34 is a partial cross-sectional view illustrating still another example of the prism groove shape of the prism sheet installed on the liquid crystal display element side in the present embodiment, and FIG. g. 35 is an explanatory view of an example of a light reflection processing surface formed on the lower surface of the light guide plate used in each embodiment of the present invention. Fi g. 36 is a light guide plate used in each embodiment of the present invention. FIG. 37 is a schematic diagram for explaining another embodiment, and FIG. 37 is a schematic diagram for explaining the effect of the backlight in the liquid crystal display device according to the present invention.

[Best mode for carrying out the invention]

FIG. 1 is a schematic diagram of a main part of an embodiment of a liquid crystal display device according to the present invention, wherein 1 is a liquid crystal display element, 2 is a backlight, 3 is a light guide plate, 4 is a cold cathode fluorescent lamp, 5 Is a lamp reflecting sheet, 6 is a collimating lens sheet, 7 is a reflecting tape, 8 is one or more prism sheets, and 9 is a reflecting sheet.

In the figure, a backlight 2 faces a light guide plate 3 made of a transparent plate having a rectangular cross section, a cold cathode fluorescent lamp 4 installed along one side edge thereof, and a light guide plate 3 of the cold cathode fluorescent lamp 4. (Light incident surface) A lamp reflecting sheet 5 installed around the side excluding the side, a collimator lens sheet 6 installed on the light guide plate 3 along the writing light surface, and the cold cathode fluorescent lamp 4 of the light guide plate 3 A reflective sheet 7 placed on the side edge opposite to the above, a prism sheet 8 placed on the upper surface of the light guide plate 3, that is, on the liquid crystal display element 1 side, and a reflective sheet 9 placed below the light guide plate 3. It is composed of The above-mentioned prism sheet includes at least one sheet having a prism groove on at least the light guide plate side, and one or more prism sheets having different groove directions can be laminated thereon. Further, the lower surface of the light guide plate 3 is subjected to light reflection processing such as a prism array.

The light guide plate 3 is, for example, an acrylic resin plate having a length of 15.5 mm in the vertical direction (vertical direction), a length of 21.8 mm in the horizontal direction (horizontal direction), a thickness of 4 mm, and a refractive index of around 1.5. The lower surface of the transparent plate is treated to avoid total reflection. There are two types of processing to avoid total reflection: processing mainly based on light scattering (diffuse reflection) and processing mainly based on regular reflection of light. There are two types of processing mainly based on light scattering: a method in which a light scattering ink material is pattern-printed on the lower surface of the transparent plate, and a method in which the T® of the transparent plate is roughened. As a process mainly based on regular reflection of light, there is a method of forming a prism array on the lower surface of a transparent plate.

The light beam incident on the light entrance surface of the light guide 3 from the cold cathode fluorescent lamp 4 is collimated by the collimating lens sheet 6 provided between the light entrance surface and the cold cathode fluorescent lamp 4.

The light beam collimated by the collimator lens sheet 6 propagates inside the light guide plate 3 while repeating regular reflection and scattering in the direction of the reflection tape 7, while passing through the prism sheet 8 from the upper surface of the light guide plate 3. The liquid crystal display element 1 is illuminated. In the liquid crystal display element 1, a predetermined pixel is set to a light transmitting state or a light blocking state by a drive circuit (not shown), and illumination light from the backlight 2 passes or blocks the pixel in the light transmitting state or the light blocking state. Then, a visual display is made.

The reflection sheet 9 reflects the light emitted from the lower surface of the light guide plate 3 in the direction of the light guide plate 3 and is installed in order to use the light effectively.The reflection tape 7 controls the light exiting from the light guide plate 3. It has the function of returning to the light guide plate 3 again.

FIG. 5 is a partially broken plan view illustrating the installation state of the collimator lens sheet constituting the backlight in FIG.

As shown in the figure, the collimating lens sheet 6 is disposed close to the light entrance surface 3 b of the light guide plate 3, that is, the side edge where the cold cathode fluorescent lamp 4 is installed. The light beam emitted from the lamp 4 passes through the collimating lens sheet 6 and is collimated in a predetermined direction.Then, the light beam enters the light guide plate 3 and repeats regular reflection and scattering to form a liquid crystal from the upper surface of the light guide plate 3. Light is emitted in the direction of the display element.

FIG. 6 is an explanatory view of a first example of a collimating lens sheet constituting a backlight according to the present invention, wherein (a) is a cross-sectional view of FIG.

(b) is a perspective view of the collimator lens sheet viewed from the light incident surface 3b side of the light guide plate 3,

(c) is a partial cross-sectional view taken along the line B-Bdi of (b), 6 and 7 are a collimator lens sheet of this example, and 6a is a prism groove.

In this example, the light guide plate 3 is a transparent resin plate having the same thickness from the side edge of the cold cathode fluorescent lamp installation side to the reflective tape 7 side, and as a process for avoiding total reflection in the transparent resin plate, the lower surface of the transparent resin plate is used. Is formed with a prism array 3a as a light reflection processing surface. The collimator lens sheet 6, which is located on the side edge of the cold cathode fluorescent lamp installation, has a number of prism grooves 6a parallel to the plane of the light guide 3 (parallel to the longitudinal direction of the cold cathode fluorescent lamp 4). 3 is provided on the light incident surface 3 b side, and the side facing the cold cathode fluorescent lamp 4 is a flat surface. The opening angle 0 of the prism groove 6 a is 90. Or 1 1 0. The pitch is set to 31 to 51.

By the collimator lens sheet 6, the light beam emitted from the cold cathode fluorescent lamp 4 is collimated in the normal direction of the collimating lens sheet 6, on a plane orthogonal to the extending direction of the prism groove 6a. Light enters the light guide plate 3. As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 enters the light incident surface of the light guide plate 3 in a plane parallel to the plane of the drawing, and is smaller than that without the collimating lens sheet 6, Incident at an angle. Taking into account the refraction effect on the light entrance surface 3b, the light flux entering the light guide plate 3 travels through the light guide plate 3 in a state where it is collimated within a narrower angle range in a plane parallel to the paper surface. Will be. The direction of travel of this light beam is controlled by specular reflection on the inclined surface of the prism array 3a disposed on the lower surface of the light guide plate 3 on the side where the cold cathode fluorescent lamp is installed, and critical when the inner surface is reflected on the upper surface of the light guide plate 3. By making the light incident at an angle of incidence smaller than the angle, the light beam can be emitted from the upper surface of the light guide plate while being collimated in a plane parallel to the paper surface. The direction of travel of the emitted light beam is determined by the internal reflection on the inclined surface on the side of the reflection tape 7 of the prism sheet (see FIG. 24) whose bottom surface is set on the upper surface of the light guide plate 3. By controlling the direction in a direction close to the normal direction of the upper surface of the LCD, a high-luminance illumination light source is realized as a backlight for a liquid crystal display.

FIG. 7 is an explanatory view of a second example of the collimating lens sheet constituting the backlight according to the present invention, wherein (a) is a cross-sectional view of FIG.

(C) is a partial cross-sectional view taken along C one C line of (b), 6 ₂ are collimation one evening lens sheet of the present embodiment, 6 b are prism grooves.

Also in this example, the light guide plate 3 is a transparent resin plate having the same thickness from the side edge of the cold cathode fluorescent lamp installation side to the reflection tape 7 side, and as a process for avoiding total reflection in the transparent resin plate, the lower surface of the transparent resin plate is used. Is formed with a prism array 3a. The guiding many Burizumu groove 6 b to the collimator lens sheet 6 _2, which is located in the cold cathode fluorescent lamp installation side edge direction orthogonal to the plane of the light guide plate 3 (the direction perpendicular to the longitudinal direction of the cold cathode fluorescent lamp) It is provided on the light incident surface 3 b side of the light plate 3, and the side facing the cold cathode fluorescent lamp 4 is a flat surface.

The opening angle 0 of the prism groove 6 b is 90. Or 1 1 0. The pitch is set to 31 to 51 m.

The light emitted from the cold cathode fluorescent lamp 4 is collimated by the collimating lens sheet 6 in a direction normal to the collimating lens sheet 62 on a plane orthogonal to the extending direction of the prism groove 6b. Light enters the light guide plate 3. Thus, most of the light beams emitted from the cold cathode fluorescent lamp 4 with respect to the incident surface 3 b of the light guide plate 3, in a plane perpendicular to the plane, smaller incidence than If there is no collimator lens sheet 6 ₂ Incident at an angle. Taking into account the refraction effect on the light entrance surface 3b, the light flux entering the light guide plate 3 travels through the light guide plate 3 in a state where it is collimated within a narrower angle range in a plane perpendicular to the paper surface. Become. The direction of travel of this light beam is controlled by specular reflection on the side of the cold cathode fluorescent lamp on the side of the cold cathode fluorescent lamp of the prism array 3a arranged in the TS of the light guide plate 3, and is critical when the inner surface is reflected on the upper surface of the light guide plate 3. By making the light incident at an incident angle smaller than the angle, the light beam can be emitted from the upper surface of the light guide plate while being collimated in a plane perpendicular to the paper surface. The direction of travel of this emitted light beam is closer to the normal direction of the upper surface of the light guide plate 3 due to internal reflection on the slope of the reflection tape 7 side of the prism sheet whose bottom surface is installed on the upper surface of the light guide plate 3. By controlling the direction, a high-brightness illumination light source is realized as a backlight for liquid crystal.

FIG. 8 is an explanatory view of a third example of the collimating lens sheet constituting the backlight according to the present invention. (A) is a cross-sectional view of FIG. b) is a perspective view of the collimator Isseki lens sheet from the cold cathode fluorescent lamp 4 side, (c) is a partial sectional view taken along D-D line in (b), 6 ₃ this example of a collimator lens The sheet, 6c, is a micro-convex lens.

Also in this example, the light guide plate 3 is a transparent resin plate having the same thickness from the side edge of the cold cathode fluorescent lamp installation side to the reflection tape 7 side, and as a process for avoiding total reflection in the transparent resin plate, the lower surface of the transparent resin plate is used. Is formed with a prism array 3a. In addition, the collimator lens sheet 63 located on the side edge of the cold cathode fluorescent lamp installation side has a large number of minute convex lenses 6 c on the surface facing the cold cathode fluorescent lamp 4, and has a light incident surface 3 b of the light guide plate 3. The opposite side is flat.

The collimator lens sheet 6 _3, light emitted from the cold cathode fluorescent lamp 4 is collimated in both sides of the plane perpendicular to the paper surface and a plane parallel to the plane with respect to the light guide plate 3 by lenticules 6 c Light enters the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 is collimated with respect to the light incident surface 3b of the light guide plate 3 in both a plane parallel to the paper and a plane perpendicular to the paper. Incident at small angles of incidence than without the meter lens sheet 6 _3. Taking into account the refraction effect on the light entrance surface 3b, the light flux entering the light guide plate 3 is collimated within a narrower angle range on both surfaces in a plane parallel to the paper and in a plane perpendicular to the paper. In this state, the light travels through the light guide plate 3. The direction of travel of this light beam is controlled by specular reflection on the slope of the cold cathode fluorescent lamp installation side of the prism array 3 a disposed on the lower surface of the light guide plate 3, and the critical angle at the time of internal reflection on the upper surface of the light guide plate 3. By making the light incident at a smaller angle of incidence, the light beam can be emitted from the upper surface of the light guide plate while being collimated in a plane parallel and perpendicular to the paper. The direction of travel of this emitted light beam is closer to the normal direction of the upper surface of the light guide plate 3 due to internal reflection on the slope of the reflection tape 7 side of the prism sheet whose bottom surface is installed on the upper surface of the light guide plate 3. By controlling the direction, a high-brightness illumination light source is realized as a backlight for liquid crystal.

FIG. 9 is a partially broken plan view illustrating another installation state of the collimating lens sheet constituting the backlight in FIG.

As shown in the figure, the collimator lens sheet 6 is arranged closely to the light incident surface 3 b of the light guide plate 3, that is, the side edge where the cold cathode fluorescent lamp 4 is installed. The light emitted from the light guide plate 6 is collimated in a predetermined direction by passing through the collimator lens sheet 6, and thereafter enters the light guide plate 3, and is emitted from the upper surface of the light guide plate 3 while being reflected and propagated. The lower surface of the light guide plate 3 is subjected to light reflection processing such as a prism groove.

FIG. 10 is an explanatory diagram of a fourth example of the collimating lens sheet constituting the backlight according to the present invention.

In this example, the light guide plate 3 is a transparent resin plate having the same thickness from the side edge of the cold cathode fluorescent lamp installation side, that is, from the light incident surface 3b to the reflection tape 7 side, and is used as a process for avoiding total reflection in the transparent resin plate. The prism array 3a is formed on the transparent resin plate. The collimator lens sheet 6, which is located on the side edge of the cold cathode fluorescent lamp installation side, has a number of prism grooves 6 a parallel to the plane of the light guide plate 3 (parallel to the longitudinal direction of the cold cathode fluorescent lamp 4). The light incident surface 3 b of the light guide plate 3 is installed in contact with the light incident surface 3 b, and the light incident surface 3 b facing the cold cathode fluorescent lamp 4 is a flat surface. The prism groove 6a has an opening angle of 90 as in the case of FIG. Or set to 100 '.

The light beam emitted from the cold cathode fluorescent lamp 4 is collimated by the collimator lens sheet 6 in a direction normal to the collimator lens sheet 61 on a plane orthogonal to the extending direction of the bism groove 6a. And enters the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 enters the light incident surface 3b of the light guide plate 3 in a plane parallel to the plane of the drawing, and is smaller than that without the collimator lens sheet 6, Incident at an angle. Taking into account the refraction effect on the light entrance surface 3b, the luminous flux entering the humiliated light plate 3 travels through the light guide plate 3 in a state where it is collimated within a narrower angle range in a plane parallel to the paper. Become. The direction of travel of this luminous flux is controlled by specular reflection on the slope of the prism array arranged on the lower surface of the light guide plate 3 on the side where the cold cathode fluorescent lamps are installed, and critical when internal reflection occurs on the upper surface of the light guide plate 3. By making the light incident at an incident angle smaller than the angle, the light beam can be emitted from the upper surface of the light guide plate while being kept collimated in a plane parallel to the paper surface. The direction of travel of the emitted light beam is adjusted by the internal reflection on the slope on the reflection tape 7 side of the bism sheet (see FIG. 24) whose bottom surface is placed on the upper surface of the light guide plate 3. By controlling the direction close to and normal to the normal direction, a high-luminance illumination light source can be realized as a backlight for liquid crystal.

FIG. 11 is an explanatory diagram of a fifth example of the collimator lens sheet constituting the backlight according to the present invention.

Also in this example, the light guide plate 3 is a transparent resin plate having the same thickness from the side edge of the cold cathode fluorescent lamp installation side, that is, from the light incident surface 3 b side to the reflection tape 7 side, and a process for avoiding total reflection in the transparent resin plate is performed. The prism array 3a is formed on the lower surface of the transparent resin plate. The collimating lens sheet 62 located on the light incident surface 3b guides many prism grooves 6b in a direction perpendicular to the plane of the light guide plate 3 (a direction perpendicular to the longitudinal direction of the cold cathode fluorescent lamp 4). It is provided on the light incident surface 3 b side of the light plate 3 and is installed in contact with the light incident surface 3 b of the light guide plate 3, and the side facing the cold cathode fluorescent lamp 4 is a flat surface.

The opening angle of the prism groove 6b is also set at ^90β to 110 ^° . The collimator lens sheet 6 _2, light beams emitted from the cold cathode fluorescent lamp 4 Are collimated in the direction normal to the collimator lens sheet 61 and are incident on the light guide plate 3.

Thus, most of the light beams emitted from the cold cathode fluorescent lamp 4 with respect to the incident surface 3 b of the light guide plate 3, in a plane perpendicular to the plane, smaller incidence than If there is no collimator lens sheet 6 ₂ Incident at an angle. Taking into account the refraction effect on the light incident surface 3b, the light flux entering the light guide plate 3 travels inside the light guide plate 3 in a plane that is collimated within a narrower angle range in a plane perpendicular to the paper surface. Will be. The direction of travel of this light beam is controlled by specular reflection at the slope of the prism array arranged on the lower surface of the light guide plate 3 on the side where the cold cathode fluorescent lamp is installed. By making the light incident at a small incident angle, the light beam can be emitted from the upper surface of the light guide plate while being collimated in a plane perpendicular to the paper surface. The traveling direction of the emitted light beam is changed to a direction closer to the normal direction of the upper surface of the light guide plate 3 due to internal reflection on the inclined surface on the reflection tape 7 side of the prism sheet having the bism surface with the lower surface installed on the upper surface of the light guide 3. By controlling the direction, an illuminating light source with high brightness is realized as a backlight for liquid crystal.

FIG. 12 is an explanatory diagram of a sixth example of the collimated lens sheet constituting the backlight according to the present invention.

Also in this example, the light guide plate 3 is a transparent resin plate having the same thickness from the cold cathode fluorescent lamp installation side edge, that is, from the light incident surface 3 b to the reflection tape 7 side, and as a process for avoiding total reflection on the transparent resin plate 內A prism array 3a is formed on the lower surface of the transparent resin plate. The collimator Isseki lens sheet 6 ₃ located on the light incident surface 3 b has a number of lenticules 6 c on the surface facing the cold cathode fluorescent lamp 4, the light incident surface 3 b side the light guide plate with the flat surface Are arranged close to the light incident surface 3b.

Due to the collimator lens sheet 63, the light emitted from the cold cathode fluorescent lamp 4 is collimated by the minute convex lens 6c into the light guide plate 3 in both a plane parallel to the paper and a plane perpendicular to the paper. Light enters the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 is collimated with respect to the light incident surface 3b of the light guide plate 3 in both a plane parallel to the paper and a plane perpendicular to the paper. The incident light is incident at a smaller incident angle than when the lens sheet 62 is not provided. The luminous flux entering the light guide plate 3 travels through the light guide plate 3 in a state of being collimated in both a plane parallel to the paper surface and a plane perpendicular to the paper surface. The direction of travel of this light beam is controlled by specular reflection on the inclined surface of the prism array 3a formed on the lower surface of the light guide 3 on the side where the cold cathode fluorescent lamp is installed, and is critical when the inner surface is reflected on the upper surface of the light guide plate 3. By making the light incident at an angle of incidence smaller than the angle, the light beam can be emitted from the upper surface of the light guide plate in a state of being kept collimated in a plane parallel and perpendicular to the paper surface. The traveling direction of the emitted light beam is closer to the normal direction of the upper surface of the light guide plate 3 due to internal reflection on the inclined surface on the reflection tape 7 side of the brhythm sheet whose bottom surface is set on the upper surface of the light guide plate 3. By controlling the direction, a high-brightness illumination light source can be realized as a liquid crystal backlight.

FIGS. 13A and 13B are explanatory views of a seventh example of the collimating lens sheet constituting the backlight according to the present invention, wherein FIG. 13A is a plan view and FIG. 13B is a plan view of FIG. It is sectional drawing cut | disconnected by the line.

The collimating lens sheet 6, ′ in this example has a groove 6 a ′ extending in a direction parallel to the plane of the light guide plate 3, and the shape and pitch of the groove 6 a ′ are vertically shifted from the center in the vertical direction. It is formed with a gradation so as to gradually change toward the side. As shown in Fig. 5 or Fig. 9, the collimated overnight lens sheet 6 'is placed between the cold cathode fluorescent lamp and the light entrance surface 3b of the light guide plate 3 to provide the cold cathode fluorescent light. The amount of light and the traveling direction from the lamp 4 to the light guide plate 3 through the collimator lens sheet 6! 'Are uniform between the pitches, realizing an illumination light source with high brightness and high uniformity. Is done.

FIG. 14 is an explanatory view of an eighth example of the collimated lens sheet constituting the backlight according to the present invention, wherein (a) is a plan view and (b) is an F-F of (a). It is sectional drawing cut | disconnected by the line.

The collimated overnight lens sheet 6 ₂ ′ in this example has a groove 6 b ′ extending in a direction perpendicular to the plane of the light guide plate 3, and the shape and pitch of the groove 6 b ′ are right and left from the center in the horizontal direction. It is formed with a gradation so that it changes gradually toward the outside. By installing this collimating overnight lens sheet 6 ₂ ′ between the cold cathode fluorescent lamp 4 and the light incident surface 3 b of the light guide plate 3 as shown in FIG. 5 or FIG. The luminous flux coming out of the fluorescent lamp 4 to the light guide plate 3 through the collimating lens sheet 6 ₂ ′ is uniform between the pitches in both the amount and the traveling direction, and an illumination light source having high brightness and high uniformity is obtained. Is achieved.

FIG. 15 is an explanatory view of a ninth example of a collimated lens sheet constituting the backlight according to the present invention, wherein (a) is a plan view and (b) is a GG of (a). FIG. 3C is a cross-sectional view taken along line H-H of FIG.

The collimating lens sheet 6 _{4 in} this example has a large number of convex lenses 6 c ′ on the surface facing the light incident surface 3 b of the light guide plate 3, and the shape and radius of curvature of the convex lens 6 c ′ are different from those of the light guide plate 3. It is formed with a gradation so that it gradually changes from the center of the light incident surface 3b in the vertical direction.

By installing this collimated overnight lens sheet 6 ₃ ′ between the cold cathode fluorescent lamp 4 and the light entrance surface 3 b of the light guide plate 3 as shown in FIG. 5 or FIG. The luminous flux from the fluorescent lamp 4 to the light guide plate 3 side via the collimator lens sheet 6 ₃ ′ becomes uniform between the convex lenses in both the amount and the traveling direction, and an illumination light source with high brightness and high uniformity is realized. .

FIG. 16 is an explanatory diagram of a tenth example of a collimating lens sheet constituting a backlight according to the present invention, wherein (a) is a plan view and (b) is an I-line of (a). It is sectional drawing cut | disconnected by IDi.

This example collimator Isseki Renzushi one DOO 6 ₄ has two types of prism grooves 6 d intersecting the surface facing the light incident surface 3 b of Shirubeko扳3.

By installing the collimating lens sheet 6 ₄ between F i g. 5 or F i g. 9 incident surface 3 b of the cold cathode fluorescent lamp 4 and the light guide plate 3 as shown in each of the prisms厶In two planes perpendicular to the groove, light is incident at a smaller incident angle than when there is no collimating lens sheet 64. Taking into account the refraction effect on the light entrance surface 3b, the luminous flux entering the light guide plate 3 is collimated within a narrower angle range in two planes perpendicular to the respective prism grooves. The light travels through the light guide plate 3. The traveling direction of this light beam is controlled by specular reflection on the inclined surface of the prism array 3a formed at T of the light guide plate 3, and the light is incident at an incident angle smaller than the critical angle at the time of internal reflection on the upper surface of the light guide plate 3. Depending on each prism groove The light beam can be emitted from the upper surface of the light guide plate 3 while being kept collimated in the two vertical surfaces. By controlling the direction of the emitted light beam in the direction normal to the upper surface of the light guide plate 3 by using a prism sheet placed on the upper surface of the light guide plate 3, high-luminance illumination as a liquid crystal backlight is achieved. A light source is realized. The shape and pitch of the prism groove 6 d may have gradation similarly to FIGS. 13 and 14.

FIG. 17 is a schematic view of a principal part for explaining another embodiment of the liquid crystal display device according to the present invention, wherein 1 is a liquid crystal display element, 2 is a backlight, 3 is a light guide plate, and 4 is a cold cathode fluorescent lamp. , 5 is a lamp reflection sheet, 6 is a collimator lens sheet, 7 is a reflection tape, 8 is a prism sheet, and 9 is a reflection sheet.

In the figure, a backlight 2 is composed of a light guide plate 3 made of a transparent plate having a wedge-shaped cross section in a direction orthogonal to the longitudinal direction of the cold cathode fluorescent lamp 4, and a cold cathode fluorescent lamp 4 installed along one side edge thereof. A lamp reflecting sheet 5 provided around the cold cathode fluorescent lamp 4 except for a side facing the light guide plate 3; a collimating lens sheet 6 provided along the one side of the light guide 3; A reflection tape 7 provided on a side edge of the light guide plate 3 opposite to the cold cathode fluorescent lamp 4, a prism sheet 8 having a prism groove on a lower surface placed on the liquid crystal display element 1 side (upper surface); The light guide plate 3 is composed of a reflective sheet 9 provided on the lower surface of the light plate 3. Acrylic resin plate with a thickness of 4 mm on the lamp side, 2 mm on the reflective tape side, and a refractive index of around 1.5 It is composed of a transparent plate such as T® that has been subjected to light reflection processing to avoid total internal reflection in the area near the light entrance surface. There are two types of processing to avoid total reflection: processing based mainly on light scattering and processing based mainly on regular reflection of light. There are two types of processing mainly based on light scattering: a method of pattern printing an ink material having a light scattering property on the lower surface of the transparent plate, and a method of performing rough surface processing on T® of the transparent plate. As a process mainly based on regular reflection of light, there is a method of forming a prism array on the lower surface of a transparent plate.

Light incident from the cold cathode fluorescent lamp 4 on the light entrance surface of the light guide 3 is collimated by the collimating lens sheet 6 installed between the light entrance surface and the cold cathode fluorescent lamp 4. It is.

The light collimated by the collimator lens sheet 6 illuminates the liquid crystal display element 1 from the upper surface of the light guide plate 3 through the prism sheet 8 while repeating regular reflection and scattering in the direction of the reflection tape 7 in the light guide plate 3. .

In the liquid crystal display element 1, a predetermined pixel is in a light transmitting or light blocking state by a drive circuit (not shown), and illumination light from the backlight 2 passes through or blocks the pixel in the light transmitting or light blocking state. Then, a visual display is made.

FIG. 18 is an explanatory view of a first example of a collimating lens sheet constituting a backlight according to the present invention, and 6, is a collimating lens sheet similar to FIG. Denotes a prism groove.

In this example, the light guide plate 3 is a wedge-shaped transparent resin plate having a thickness that gradually decreases from the side edge of the cold cathode fluorescent lamp installation, that is, from the light incident surface 3 b to the reflection tape 7 side, and the transparent resin near the light incident surface 3 b is formed. As a process for avoiding total reflection within the plate, a prism array 3a is formed on the lower surface of the transparent resin plate. Also, the collimator lens sheet 6, located on the light entrance surface 3 b, has a number of prism grooves 6 a parallel to the plane of the light guide plate 3 (parallel to the longitudinal direction of the cold cathode fluorescent lamp 4) to enter the light guide plate 3. It is provided on the surface 3b side, and the side facing the cold cathode fluorescent lamp 4 is a flat surface.

The opening angle 0 of the prism groove 6 a is 90. 1 to 110 ^β , the pitch is set to 31 to 51〃m.

Due to the collimator lens sheet 6, the light emitted from the cold cathode fluorescent lamp 4 is placed on a plane orthogonal to the extending direction of the bism groove 6a, and is directed in the normal direction of the collimating lens sheet 6, The light is collimated and enters the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 enters the light incident surface 3b of the light guide plate 3 in a plane parallel to the plane of the drawing, and is smaller than that without the collimator lens sheet 6, Incident at an angle. Taking into account the refraction effect on the light entrance surface, the light flux entering the light guide plate 3 is in a plane parallel to the paper plane, narrower, and collimated in the angle range. It will travel inside the light guide plate 3 with the mated prone. The direction of travel of this luminous flux is controlled by specular reflection on the inclined surface of the prism array 3a formed on the lower surface of the light guide plate 3 on the cold cathode fluorescent lamp installation side, and the critical angle at the time of internal reflection on the upper surface of the light guide plate 3 By making the light incident at a smaller incident angle, the light beam can be emitted from the upper surface of the light guide plate 3 toward the liquid crystal display element 1 while being collimated in a plane parallel to the paper. The direction of travel of this emitted light beam is directed to a direction closer to the normal direction of the upper surface of the light guide plate 3 due to internal reflection on the inclined surface on the reflection tape 7 side of the bism sheet whose bottom surface is placed on the upper surface of the light guide plate 3. By controlling, an illumination light source with high brightness is realized as a backlight for liquid crystal.

F ig. 1 9 is an explanatory view of the first two examples collimation Isseki lens Sea Bok constituting the backlight in the present invention, 6 ₂ F ig. 7 the same collimation Isseki lens sheet, 6 b Denotes a prism groove.

Also in this example, the light guide plate 3 is a wedge-shaped transparent resin plate having a thickness that gradually decreases from the light incident surface 3 b side to the reflective tape 7 side, thereby avoiding total reflection in the transparent resin plate in a region near the light incident surface. As a process, a prism array 3a is formed on a TIB of a transparent resin plate. The light incident surface 3 b side position S has been collimation Isseki lens sheet 6 ₂ number of prism grooves 6 b in a direction (direction perpendicular to the longitudinal direction of the cold cathode fluorescent lamp 4) perpendicular to the plane of the light guide plate 3 On the light guide plate 3 side, and the side facing the cold cathode fluorescent lamp 4 is a flat surface.

The opening angle 0 of the prism groove 6b is set to 90 ′ to 110 ^β .

The collimator lens sheet 6 _2, light emitted from the cold cathode fluorescent lamp 4 in a plane orthogonal to the extending direction of the prism grooves 6 b, it is collimated in the direction normal to the collimator Isseki lens sheet 6 ₂ guide Light is incident on the light plate 3.

Thus, most of the light beams emitted from the cold cathode fluorescent lamp 4 with respect to the incident surface 3 b of the light guide plate 3, in a plane perpendicular to the plane, smaller incidence than If there is no collimator lens sheet 6 ₂ Incident at an angle. Taking into account the refraction effect on the light entrance surface, the light flux entering the light guide plate 3 travels through the light guide plate 3 in a state where it is collimated within a narrower angle range in a plane perpendicular to the paper surface. Become. The traveling direction of this light beam is set on the slope of the prism array 3a formed on the lower surface of the light guide plate 3 on the cold cathode fluorescent lamp installation side. The direction of the beam is controlled by specular reflection at the inner surface of the light guide plate 3 and the light is incident at an angle of incidence smaller than the critical angle at the time of internal reflection at the upper surface of the light guide plate 3, so that the light beam is kept collimated in a plane perpendicular to the paper surface The light can be emitted from the upper surface. The direction of travel of the emitted light beam is closer to the normal direction of the upper surface of the light guide plate 3 due to internal reflection on the inclined surface on the reflection tape 7 side of the prism sheet whose bottom surface is installed on the upper surface of the light guide plate 3. By controlling the direction, a high-luminance illuminating light source is realized as a backlight for liquid crystal.

F i g. 2 0 is fit in illustration of the first three examples collimation Isseki lens sheet that constitute the backlight in the present invention, 6 ₃ F ig. 7 the same collimation Isseki lens sheet, 6 c Is a micro convex lens.

Also in this example, the light guide plate 3 is a wedge-shaped transparent resin plate having a thickness that gradually decreases from the light incident surface 3 b side of the light guide plate 3 to the reflective tape 7 side. As a process for avoiding total reflection, a prism array 3a is formed on the lower surface of the transparent resin plate. The cold cathode fluorescent lamp installation side edge collimator Isseki lens sheet 6 _3, which is located has a number of lenticules 6 c on the surface facing the cold cathode fluorescent lamp 4, the light guide plate 3 side is a flat surface I have.

The collimator Isseki lens sheet 6 _3, collimator in both sides of the cold cathode fluorescent lamp 4 in a plane perpendicular to the parallel plane and the plane to the plane with respect to the light guide plate 3 light emitted by lenticules 6 c from The light is incident on the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 is collimated by the collimator lens with respect to the light entrance surface 3b of the light guide plate 3 in both a plane parallel to the paper and a plane perpendicular to the paper. incident at small angles of incidence than without sheet 6 _3. Taking into account the refraction effect on the light entrance surface, the luminous flux entering the light guide plate 3 was collimated within a narrower angle range in both surfaces parallel to the paper and perpendicular to the paper. In this state, the light travels through the light guide plate 3. The direction of travel of this light beam is controlled by specular reflection on the inclined side of the cold cathode fluorescent lamp installation side of the prism array 3a formed on the lower surface of the light guide plate 3, so that the inner surface reflects from the upper surface of the light guide plate 3 from the critical angle. Incident on the liquid crystal display element from the upper surface of the light guide plate 3 while being collimated in a plane parallel and perpendicular to the plane of the paper. Can be. The traveling direction of the emitted light beam is closer to the normal direction of the upper surface of the light guide plate 3 due to the internal reflection of the lower surface provided on the upper surface of the light guide plate 3 on the slope of the prism sheet on the reflection tape 7 side of the prism surface. By controlling the direction, a high-luminance illumination light source is realized as a backlight for liquid crystal.

FIG. 21 is an explanatory diagram of a 14th example of the collimator lens sheet constituting the backlight according to the present invention.

In this example, the light guide 3 is a wedge-shaped transparent resin plate whose thickness gradually decreases from the side edge of the cold cathode fluorescent lamp installation, that is, the light incident surface 3 b to the reflective tape 7 side, and the area near the light incident surface 3 b In order to avoid total reflection in the transparent resin plate, a prism array 3a is formed on the lower surface of the transparent resin plate. The collimator sheet 6, located on the light incident surface 3 b side, has a large number of prisms parallel to the plane of the light guide plate 3 (parallel to the longitudinal direction of the cold cathode fluorescent lamp 4), as in FIG. 6. The light guide plate 3 has a groove 6a, which is installed in contact with the light entrance surface of the light guide plate 3, and the side facing the cold cathode fluorescent lamp 4 is a flat surface.

The opening angle of the prism groove 6a is set to 90 'to 110' similarly to the above-mentioned respective examples.

The light beam emitted from the cold-cathode fluorescent lamp 4 is collimated by the collimating lens sheet 6 in a direction normal to the collimator lens sheet 6 on a plane orthogonal to the extending direction of the prism groove 6a. Light enters the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 is incident on the light incident surface 3b of the light guide plate 3 in a plane parallel to the plane of the paper, compared with the case where there is no collimating lens sheet 6,. Incident at a small incident angle. Taking into account the refraction effect on the light entrance surface 3b, the luminous flux entering the light guide plate 3 travels through the light guide plate 3 in a state where it is collimated within a narrower angle range in a plane parallel to the paper surface. Become. The direction of travel of this light beam is controlled by specular reflection on the slope of the cold cathode fluorescent lamp installation side of the prism array 3a formed on the lower surface of the light guide plate 3, and critical when the inner surface reflects on the upper surface of the light guide plate 3. By making the light incident at an angle of incidence smaller than the angle, the light beam can be emitted from the upper surface of the light guide plate to the liquid crystal display element side in a collimated state in a plane parallel to the paper surface. The direction of travel of this emitted light beam is guided by the internal reflection of the slope on the reflection tape 7 side of the breath sheet on the breath surface by the T® installed on the upper surface of the light guide plate 3. By controlling the direction close to and normal to the normal direction of the upper surface of the light plate 3, a high-brightness illumination light source is realized as a liquid crystal backlight.

FIG. 22 is an explanatory diagram of a fifteenth example of the collimator lens sheet constituting the backlight according to the present invention.

Also in this example, the light guide plate 3 is a wedge-shaped transparent resin plate having a thickness gradually reduced from the light incident surface 3b side to the reflection tape 7 side, and the total reflection in the transparent resin plate in the region near the light incident surface 3b is suppressed. As a evacuating process, a prism array 3a is formed on T® of the transparent resin plate. The collimator lens sheet 62 located on the light incident surface 3 b side has a number of prism grooves 6 b in a direction perpendicular to the plane of the light guide plate 3 (a direction perpendicular to the longitudinal direction of the cold cathode fluorescent lamp 4). It is provided on the light guide plate 3 side, is installed in contact with the light entrance surface of the light guide plate 3, and the side facing the cold cathode fluorescent lamp 4 is a flat surface.

The opening angle of the prism groove 6b is also 90. Or 100. Is set to The collimator Isseki lens sheet 6 _2, light beams emitted from the cold cathode fluorescent lamp 4 Te Ore, on a plane orthogonal to the extending direction of the prism grooves 6 b, the normal direction of the collimator lens sheet 6 ₂ And is incident on the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 is incident on the light incident surface 3 b of the light guide plate 3 in a plane perpendicular to the plane of the paper, compared with the case where the collimating lens sheet 6 ₂ is not provided. Incident at a small incident angle. Taking into account the refraction effect on the light entrance surface 3b, the light flux entering the light guide plate 3 travels through the light guide plate 3 in a state where it is collimated within a narrower angle range in a plane perpendicular to the paper surface. Become. The direction of travel of this light beam is controlled by specular reflection on the side of the cold cathode fluorescent lamp installation side of the prism array 3 a formed on the lower surface of the light guide plate 3, and the critical angle at the time of internal reflection on the upper surface of the light guide plate 3 is smaller than the critical angle. By making the light incident at a small incident angle, the light beam can be emitted from the upper surface of the light guide plate while being collimated in a plane perpendicular to the paper surface. The traveling direction of the emitted light beam is closer to the normal direction of the upper surface of the light guide plate 3 due to internal reflection of the lower surface provided on the upper surface of the light guide plate 3 on the slope of the reflection tape 7 side of the blister sheet. By controlling the direction, a high-brightness illumination light source can be realized as a backlight for liquid crystal.

FIG. 23 shows the collimator lens sheet constituting the backlight in the present invention. 9

FIG. 24 is an explanatory diagram of a 16th example of the FIG.

Also in this example, the light guide plate 3 is a wedge-shaped transparent resin plate having a thickness gradually reduced from the light incident surface 3 b side to the reflective tape 7 side, and the total reflection in the transparent resin near the light incident surface 3 b is performed. As a process for avoiding, a prism array 3a is formed on a transparent resin plate. The collimating lens sheet 63 located on the light incident surface 3b side has a large number of minute convex lenses 6c on the surface facing the cold cathode fluorescent lamp 4, and the light guide plate 3 side is a flat surface and the light guide plate It is placed close to the light entrance surface of the device.

The collimator Isseki lens sheet 6 _3, collimated in both sides of the cold cathode fluorescent lamp 4 in a plane perpendicular to the parallel plane and the plane to the plane with respect to the light guide plate 3 by the emitted light beam lenticules 6 c from Then, the light enters the light guide plate 3.

As a result, most of the luminous flux emitted from the cold cathode fluorescent lamp 4 is collimated by the collimator lens with respect to the light entrance surface 3b of the light guide plate 3 in both a plane parallel to the paper and a plane perpendicular to the paper. sheet 6 ₃ such les than when incident at a small angle of incidence.

The luminous flux entering the light guide plate 3 travels through the light guide plate 3 in a state of being collimated on both surfaces 內 in a plane parallel to the paper surface and in a plane perpendicular to the paper surface. The direction of travel of this light beam is controlled by specular reflection on the inclined surface of the prism array 3a formed on the lower surface of the light guide plate 3 on the cold cathode fluorescent lamp installation side, and the critical angle at the time of internal reflection on the upper surface of the light guide plate 3 is determined. By making the light incident at a smaller incident angle, the light beam can be emitted from the upper surface of the light guide plate to the liquid crystal display element side while being collimated in a plane parallel and perpendicular to the paper surface. The direction of travel of this emitted light beam is close to the normal direction of the upper surface of the light guide plate 3 due to internal reflection on the inclined surface of the prism sheet on the reflection tape 7 side where the lower surface installed on the upper surface of the light guide plate 3 is located. By controlling the direction, a high-brightness illumination light source can be realized as a liquid crystal backlight.

FIG. 24 is a schematic view of a main part for explaining still another embodiment of the liquid crystal display device according to the present invention, wherein (a) is a perspective view, and (b) is a view along a-adi of (a). FIG.

In the same figure, the light guide 扳 3 is formed of a wedge-shaped transparent plate whose thickness gradually decreases from the cold cathode fluorescent lamp 4 side toward the reflection tape 7 a, a prism sheet 8 is placed on the upper part, and a lower part is on the lower part. A reflection sheet 9 is provided. The lower surface of the light guide plate 3 has a prism Light reflecting treatment is performed on the light guide plate 3, and a reflective tape 7b is also attached to the side surface of the light guide plate 3.

A collimator lens sheet 6 is provided between the cold cathode fluorescent lamp 4 and the light incident surface 3b of the light guide plate 3.

The prism sheet 8 has a large number of prism grooves on its lower surface, and is placed with the surface on which the prism grooves are formed facing the light guide plate 3. Note that a diffusion plate can be interposed between the prism sheet 8 and the light guide plate 3.

FIG. 25 is an explanatory diagram of an emission angle distribution of luminous intensity of light emitted from the light guide plate and an emission angle distribution of luminous intensity of light emitted from the prism sheet in the present embodiment. 2) shows an emission angle distribution of the luminous intensity of the light emitted from the prism sheet.

In the figure, the end of the light guide plate where the reflective tape is attached is 0 °, and the end on the cold cathode fluorescent lamp installation side is 180 °. Then, the emission angle at which the luminous intensity of the light emitted from the unit area of the light guide plate becomes maximum (hereinafter, referred to as a peak angle) 0 is almost in the 20 ′ direction as shown in (1). The light in this direction is directed by the prism sheet to a direction of approximately 90 ° which is the liquid crystal display element direction (upward in the vertical direction) as shown in (2).

In this way, the collimator lens sheet is installed on the light entrance surface of the light guide plate to collimate the incident light to increase the light use efficiency, and the lower surface is the prism sheet with the prism sheet on the slope on the reflection tape 7 side. High-brightness illumination can be performed by making most of the light beam incident on the liquid crystal display element substantially perpendicular to the liquid crystal display element by internal reflection.

FIG. 26 is a schematic diagram for explaining the cross-sectional profile of a prism sheet having a prism surface on the lower surface used in each embodiment of the present invention.

This breath sheet has a smooth surface on the side facing the liquid crystal display element and a prism surface on the side facing the light guide plate. The smooth surface side uses a PET film with a refractive index of approximately 1.66, and the prism surface has a two-layer structure with a substantially refractive index and 1.51 acrylic resin adhered. I have.

The prism groove of the prism sheet has one slope on the reflection tape side of the light guide plate 3 and is formed in a mountain shape with the other slope on the light entrance surface 3b side, and the angle of the slope on the reflection tape side ø, Is, for example, 38 ° with respect to the diagonal of the prism sheet 6, and the slope of the light incident surface 3b side Is also 5 °, for example.

By using such a prism sheet, as shown in FIG. 25, a light beam emitted from the light guide plate at a peak angle of luminous intensity of approximately 20 ° has a peak angle of approximately 90 °. Luminous flux can be corrected.

FIG. 27 is an arrangement diagram of a light guide plate and a prism sheet for explaining the operation of the prism sheet in the present embodiment.

FIG Nio Te, respectively substantially 3 8 ° as the relative angles 0 of the peak direction of the luminous intensity of the light beam 0 ₂ was the emerging from a unit area of the light guide plate 3, and approximately 5 ° and child Accordingly, the light beam emitted from the prism sheet 8 enters the liquid crystal display element at a peak angle of about 90 °.

Fig. 28 is an explanatory view of another example of the cross-sectional shape of the breath sheet. (A) shows a flat portion 8a provided at the valley of the prism sheet shown in Fig. 27. (B) is a flat portion with a flat portion 8b, (c) is a curved portion with valleys and peaks 8c and 8d, and (d) is a flat portion with a valley. The portion 8a has a curved portion 8d at the peak, and (e) has a curved portion 8c at the valley and a flat portion 8b at the peak. In each of the prism sheets (a) and (b), the angle 01 of one slope and the angle 02 of the other slope are the same as those described in FIG.

By using the prism sheet as described above, the angle distribution of the luminous intensity of the light emitted from the upper surface of the light guide plate becomes almost perpendicular to the liquid crystal display element as described in FIG. 25 above. Incident.

FIG. 29 is a schematic diagram of a principal part for explaining still another embodiment of the liquid crystal display device according to the present invention.

In the figure, the light guide plate 3 is either a transparent plate having a uniform thickness or a wedge-shaped transparent plate whose thickness gradually decreases from the cold cathode fluorescent lamp 4 side (light incident surface 3 b side) toward the reflective tape 7. In order to avoid total reflection in the transparent resin plate, a light reflection pattern such as a blizzard array or scattering ink printing is formed on the lower surface of the transparent resin plate, or a roughening process is performed. It has been done.

Three prism sheets 8, 8 ₂ , 8 ₃ are mounted on the upper part of the light guide plate 3, and a reflection sheet 9 is arranged on the lower part. Note that reflective tape is also applied to the side of the light guide plate 3. May be attached.

Then, one of the cold cathode fluorescent lamp 4 and co Increment described in the embodiment between the light incident surface of the light guide plate 3 Isseki lens sheet 6 !, 6 _2, 6 _3. 64 is installed.

The prism sheet 8 has a number of prism grooves 8 on its lower surface (the light guide plate 3 side), and the prism groove direction 8 _lh is parallel to the cold cathode fluorescent lamp 4.

The prism sheet ₈₂ has a number of prisms grooves 8 ₂ - (opposite side to the light guide plate 3) the upper surface thereof, the prism groove direction 8 _2b is prism groove direction 8 _lb of the prism sheet 8, They are arranged at an angle.

Then, the prism sheet 8 ₃ has a number of pre-prism grooves 8 _3, (opposite side to the light guide plate 3) the upper surface thereof, the prism groove direction 8 _3b is the prism sheet ₈₂ of Brise beam groove direction 8 _2b With respect to a line perpendicular to the longitudinal direction of the cold-cathode fluorescent lamp.

Thus, of the three prism sheets, 8, together with the prism surface of toward the light guide plate 3 side, the prism surface of the 8 _2, 8 ₃ are stacked in a manner facing the liquid crystal display element side.

Note that a diffusion plate may be interposed between the prism sheet 8 and the light guide plate 3.

FIG. 30 is a schematic cross-sectional view taken along the line A—A of FIG. 29. As shown, three prism sheets 8, 8 are provided between the light guide plate 3 and the liquid crystal display element 1. , 8 _2, 8 ₃ are arranged by stacking. A light reflection processing surface 3 a is formed on the lower surface of the light guide plate 3, and a diffusion sheet 10 is interposed between the prism sheet 8 and the light guide plate 3. Is not necessary.

FIG. 31 is a fragmentary cross-sectional view for explaining the shape of the prism surface of the prism sheet in FIG. 29.

The three prism sheets 8,, 8 ₂ , 8 ₃ The prism grooves 8 _lb , 8 _2b , 8 _3b of the prism grooves 8 _lb , 8 _2b , 8 3 _b (the size of the grooves g, that is, the slope opening angle 0 The size is selected according to the illumination characteristics of the backlight, the light transmission characteristics of the liquid crystal display element, and the luminance distribution characteristics of the display surface of the liquid crystal display device. Alternatively, it can be locally different, so that the display surface of the liquid crystal display device can have a desired luminance distribution. FIG. 32 is an explanatory diagram of the relationship between the prism groove directions of the three prism sheets in the present embodiment.

In the figure, the prism groove direction 8 _lb of the prism sheet 8 on the light guide plate 3 side is in a direction parallel to the longitudinal direction of the cold cathode fluorescent lamp 4, and the prism groove direction 8 _2b of the prism sheet 8 _{2 on} the upper surface thereof is The prism sheet 8 is arranged at an angle with respect to the prism groove direction 8 _lb of the prism sheet 8.

Then, the prism groove direction 8 _3b of the prism sheet 8 ₃ of the liquid crystal display device 1 side is positioned at an angle 0 ₂ on the opposite side with respect to Bed prism sheet 8, the prism groove direction 8, _b. Note that 0, 0 ₂ are acute angles.

By arranging the three prism sheets in the above-described arrangement, the viewing angle can be increased in a plane perpendicular to the longitudinal direction of the cold cathode fluorescent lamp.

According to this embodiment, the viewing angle can be adjusted by changing the direction of each prism groove of the three breath sheets, and a liquid crystal display device adapted to the intended use can be configured.

F i g. 33 is a partial cross-sectional view illustrating another example of the prism groove shape of the prism sheet _82, 8 ₃ installed on the liquid crystal display element side in the present embodiment.

Prism sheet ₈₂ of this example (8 ₃₎ is for the prism grooves 8 _2b the (8 _3b) are cross section formed in a semicircular or partial circular shape, the light directed to the liquid crystal display device direction the F i g. Its directivity is weaker than that shown in 31. As a result, the viewing angle spreads moderately, and there is little difference in brightness between the viewing angle and the brightness of the entire display surface.

F i g. 34 is a partial cross-sectional view illustrating still another example of the prism groove shape of Purizumushi Ichito 8 _2, 8 ₃ installed on the liquid crystal display element side in the present embodiment.

Prism sheet ₈₂ of this example, the ones the shape of the prism grooves shown in the F i g. 31 to that shown in the Fi g. 33 partially adopted, central region ₍₈₂ in the prism sheet · ') And the surrounding area (8 ₂ ·).

As a result, the manner in which the viewing angle spreads can be locally changed.

Thus, according to the present embodiment, by setting the prism groove directions of the three prism sheets, it is possible to arbitrarily adjust the direction of the viewing angle and the manner of spreading. FIG. 35 is an explanatory view of an example of a light reflection processing surface formed on the lower surface of the light guide plate used in each embodiment of the present invention, in which total reflection is avoided and luminance is unified. It is a schematic diagram explaining the example of the case.

The figure shows the surface of the light guide plate 3 on the side opposite to the T®, that is, the liquid crystal display element, and the cold cathode fluorescent lamp 4 is disposed at one end.

On this lower surface, a light reflection pattern 11 such as a blizzard array or scattering ink printing is arranged so as to be linear in parallel with the longitudinal direction of the cold cathode fluorescent lamp 4, and the arrangement interval is set. The cold cathode fluorescent lamp 4 is formed so that it becomes closer as it goes away, and becomes denser as it goes to both sides of the cold cathode fluorescent lamp 4.

The light from the cold cathode fluorescent lamp 4 is specularly reflected by the prism array pattern 11, and is incident on the upper surface of the light guide plate 3 at an incident angle smaller than the critical angle at the time of internal reflection on the upper surface of the light guide plate 3, so that a plane parallel to the paper surface is obtained. The inner and outer light can be emitted from the upper surface of the light guide plate while being substantially collimated in a vertical plane or both. By controlling the traveling direction of the emitted light beam to a direction close to the normal direction of the upper surface of the light guide plate 3 by using a blism sheet with the lower surface installed on the upper surface of the light guide plate 3 for liquid crystal. A high-luminance illumination light source is realized as a backlight.

FIG. 36 is a schematic view for explaining another example of the light guide plate used in each embodiment of the present invention, wherein (a) is a sectional view and (b) is a sectional view of hollow beads.

In FIG. 1A, hollow beads 12 are dispersed in a light guide plate 3 made of an acrylic resin. As shown in FIG. 3B, the diameter of the hollow beads 12 varies from a minimum of 0.1 直径 111 to a maximum of 100〃m, but the average is 5 to 30〃m. Is the size of The thickness t of the shell is from 0.05 to several 10 / m.

The hollow layer of the hollow beads 12 may be a gas such as nitrogen, helium, argon, or neon, which has a low refractive index substantially equal to that of air in terms of the force, which is usually air, and the effect. Although the light guide plate 3 is shown as having a wedge-shaped cross section in the same figure, hollow beads may be dispersed in a flat light guide plate in the same manner as described above.

In such a structure, the light beam L emitted from the cold cathode fluorescent lamp collides with the hollow beads 12 and is scattered in the process of traveling through the light guide plate 3.

The scattered ^ collides with other hollow beads 1 2 one after another, and the scattering The enclosure expands.

There is light that reaches the upper surface of the light guide plate 3 while controlling collision and scattering with the hollow beads, and at this time light whose incident angle is smaller than total reflection is partially transmitted and guided according to Snell's law. The light exits the light plate 3.

In this way, by dispersing the hollow beads in the light guide plate, the brightness step generated at the boundary of the light reflection pattern provided on the lower surface of the light guide plate 3 is suppressed, and the brightness distribution can be equalized. By using any of the above-mentioned breath sheets, a good quality image display can be obtained.

FIG. 37 is a schematic diagram for explaining the effect of the backlight in the liquid crystal display device according to the present invention, wherein a is a light guide plate 3 which is emitted from the cold cathode fluorescent lamp 4 and collimated by the collimator lens sheet 6. B is the luminous intensity distribution of the luminous flux emitted from the upper surface of the light guide plate 3, and c is the luminous intensity distribution of the luminous flux emitted from the upper surface of the prism sheet.

As shown in the figure, the light flux having the luminous intensity distribution a collimated by the collimator lens sheet 6 propagates through the light guide plate 3 and exits from the upper surface of the light guide plate 3 with the luminous intensity distribution b.

The prism sheet 8 converts the incident light beam having the luminous intensity distribution b into an outgoing light beam c that travels substantially perpendicularly to the liquid crystal display element by the internal reflection action on the lower surface prism slope, and makes the light beam enter the liquid crystal display element.

The light guide plate is not limited to the one having a wedge-shaped cross section as shown in the figure, and the same effect can be obtained by using a flat plate.

[Industrial applicability]

As described above, according to the liquid crystal display device according to the present invention, which is configured by any one of the above-described embodiments as the collimation overnight lens sheet, the prism sheet, and the light guide plate, or a combination thereof, a high quality liquid crystal display device Can be obtained.

Further, in the liquid crystal display device according to the present invention, the luminous flux having the enhanced directivity guides the light guide plate で and emits it to the upper surface while maintaining high directivity, and the traveling direction of the emitted luminous flux The brightness of the backlight as a liquid crystal backlight can be controlled by controlling the direction of Power consumption of the surface light source device can be reduced. In addition, since a light guide plate having a thickness approximately equal to the diameter of the fluorescent lamp can be used, and the thickness of the collimating lens sheet can be reduced, the thickness can be reduced and the frame can be narrowed. be able to.

Claims

The scope of the claims

1. A light guide plate made of a transparent plate whose lower surface has been subjected to a light reflection treatment for avoiding total reflection, and a cold cathode disposed along at least one side edge of the light guide plate as a light incident surface. A fluorescent lamp, a lamp reflection sheet provided around the cold cathode fluorescent lamp except for a portion facing the light incident surface, a prism sheet provided on an upper surface of the light guide plate, and a lower portion of the light guide plate. Light emitted from the cold cathode fluorescent lamp between the cold cathode fluorescent lamp and the light incident surface of the light guide plate, at least comprising a reflection sheet provided and a liquid crystal display element provided on the upper surface of the breath sheet. A collimating lens sheet for collimating and introducing the collimated light into the light incident surface.

2. The light guide plate according to claim 1, further comprising a prism groove parallel to a longitudinal direction of the cold cathode fluorescent lamp on one surface of the collimating overnight lens sheet, and the one surface being a light incident surface of the light guide plate. A liquid crystal display device, which is installed with a small distance from it.

3. The collimator lens sheet according to claim 1, wherein the collimator lens sheet has, on one surface thereof, a prism groove perpendicular to a longitudinal direction of the cold cathode fluorescent lamp, and the one surface with respect to a light incident surface of the light guide plate. A liquid crystal display device characterized by being installed at a very small distance from the display.

4. The claim 1, wherein the collimating lens sheet has a plurality of convex lenses on one surface, and one of the one surface and the opposite surface is provided on a light incident surface of the light guide plate. A liquid crystal display device which is set apart from a small distance.

5. The collimating lens sheet according to claim 1, further comprising two types of prism grooves intersecting one surface of the collimating lens sheet, wherein the one surface is a minute distance from a light incident surface of the light guide plate. A liquid crystal display device characterized by being installed only in a room.

6. The light guide plate according to claim 1, further comprising a prism groove parallel to a longitudinal direction of the cold-cathode fluorescent lamp on one surface of the collimating lens sheet, and the one surface being incident on the light guide plate. A liquid crystal display device, which is provided in close contact with a surface.

7. The collimating lens sheet according to claim 1, wherein one surface of the collimating lens sheet has a prism groove perpendicular to a longitudinal direction of the cold cathode fluorescent lamp, and the one surface is a light incident surface of the light guide plate. A liquid crystal display device characterized by being installed in close contact with a liquid crystal display.

8. The light guide plate according to claim 1, wherein the collimating lens sheet has a large number of minute convex lenses on one surface, and either one of the one surface or the surface on the opposite side is incident on the light guide plate. A liquid crystal display device, which is provided in close contact with a surface.

9. In Claim 1, the prism sheet has two types of prism grooves intersecting with one surface of the collimating lens sheet, and the one surface is placed in close contact with the light incident surface of the light guide plate. A liquid crystal display device characterized by the above-mentioned.

10. A light guide plate made of a transparent plate whose lower surface has been subjected to light reflection processing to avoid total reflection, and a cold cathode disposed along the light incident surface with at least one side edge of the light guide plate as a light incident surface A fluorescent lamp, a lamp reflecting sheet provided around the cold cathode fluorescent lamp except for a portion facing the light incident surface, a prism sheet provided on an upper surface of the light guide plate, and a lower portion of the light guide plate. And a liquid crystal display device disposed on the upper surface of the prism sheet. The light emitted from the cold cathode fluorescent lamp is collimated between the cold cathode fluorescent lamp and the light incident surface of the light guide plate. A collimator lens sheet to be introduced into the light entrance surface, and the prism sheet has a flat surface on the liquid crystal display element side and a longitudinal direction of the cold cathode fluorescent lamp on the light guide 扳 side. Many breath grooves parallel to A liquid crystal display device comprising a single transparent sheet provided with the liquid crystal display device.

11. Light guide plate made of a transparent plate whose lower surface has been subjected to light reflection processing to avoid total reflection, and a cold cathode installed along this light entrance surface with at least one side of the light guide plate as a light entrance surface A fluorescent lamp, a lamp reflecting sheet provided around the cold cathode fluorescent lamp except for a portion facing the light incident surface, a prism sheet provided on an upper surface of the light guide plate, and a lower portion of the light guide plate. At least a reflection sheet provided, and a liquid crystal display element provided on an upper surface of the prism sheet, and emits light emitted from the cold cathode fluorescent lamp between the cold cathode fluorescent lamp and a light incident surface of the light guide plate. A collimator lens sheet for collimating and introducing the light into the light incident surface is provided, and the prism sheet has a flat surface on the liquid crystal display element side and a longitudinal direction of the cold cathode fluorescent lamp on the light guide plate side. Multiple parallel prisms And a laminate of two transparent sheets each having a flat surface on the light guide side and a prism groove on the liquid crystal display element side, respectively. A liquid crystal display device characterized in that the direction of the bristles groove intersects with the one of the one transparent sheet at an angle equal to the width of the bluish groove.

12. The liquid crystal display device according to any one of claims 1, 10, and 11, wherein minute hollow beads are dispersed in the light guide plate.