CN102147547A - Liquid crystal display element - Google Patents

Abstract

Provided is a liquid crystal display element, comprising a first substrate which has a first electrode and undergoes an orientation treatment in a first direction, a second substrate which is disposed in parallel with the first substrate and has a second electrode and undergoes an orientation treatment in a second direction, and a liquid crystal layer which is disposed between the first substrate and the second substrate, and has chiral materials and conducts a distortion orientation. The second direction is looked from a normal direction of the first substrate, and forms an angle of 70-110 DEG with a first revolution direction with respect to the first direction. Liquid crystal molecules of the liquid crystal molecule are arranged in a manner of twisting along the first revolution direction. The chiral materials supply revolution properties of a second revolution direction opposite to the first revolution direction to the liquid crystal molecules of the liquid crystal molecule along the direction of the first substrate facing the second substrate. The first and the second substrates is processed into a pretilt angle Theta which is larger than 0 DEG and no more than 5 DEG through an orientation treatment. When the thickness of the liquid crystal layer is d and the chiral distance of the chiral material is p, Theta, d and p satisfy the following formula (1) and formula (2).

Description

Liquid crystal display cells

Technical field

The present invention relates to liquid crystal display cells.

Background technology

Disclosed twisted-nematic (the twisted nematic of effective angular field of view with good demonstration contrast and broadness; TN) invention of type liquid crystal display cells (for example with reference to patent documentation 1).The liquid crystal display cells of record has such feature in the patent documentation 1: with by a pair of transparent electrode substrate at the clamping liquid crystal layer on make the liquid crystal molecule twisted arrangement on the opposite direction (second gyratory directions) of the gyratory directions (first gyratory directions) of the liquid crystal molecule that combination limited of direction of the orientation process that applies, and the orientation process of carrying out a pair of transparent electrode substrate, make the tilt angle of the liquid crystal molecule that connects with each transparent electrode substrate different mutually

In the liquid crystal display cells of patent documentation 1 record, realized the raising of electric optical characteristics, even being set at about the revolution (distortion) of first gyratory directions under 91～100 ° the situation of scope, by the effect of contrary twisted arrangement, also can access and the same electric optical characteristics of TN type liquid crystal display cells of passing through 90 ° of rubbing manipulations.In addition, because make the tilt angle of the liquid crystal molecule that connects with substrate different mutually, so can prevent because the generation of the incomplete disclination that causes of orientation of each liquid crystal molecule can access good display level.

In the nematic liquid crystal layer that has added chirality (chiral) material, the torsional direction that discloses the torsional direction below 90 ° that brings out by alignment films and liquid crystal material becomes the invention (for example with reference to patent documentation 2) of rightabout liquid-crystal apparatus.The liquid-crystal apparatus of this structure can reduce driving voltage.

Known have an invention (for example with reference to patent documentation 3) that can significantly reduce the liquid crystal cell of driving voltage.As the liquid crystal cell of record in the patent documentation 3 of one of achievement in research of present inventors,, makes the torsional direction of the liquid crystal material that brings out by the torsional direction of the liquid crystal material that combination determined of the orientation process direction of one group of alignment films and tilt angle with by chiral material so that becoming rightabout mode.Ordered state by the liquid crystal molecule of the combination defined of orientation process direction and tilt angle is called contrary distortion (evenly distortion) structure, twists (spray twist) structure because the ordered state of the liquid crystal molecule that the influence power of chiral material produces is called splash.

The splash distorted-structure only do not apply under the state of voltage stable, and stable at the state subinverse distorted-structure that applies voltage.Therefore, can make from the splash distorted-structure and transfer to contrary distorted-structure by applying voltage.In case after transferring to contrary distorted-structure, after stopping to apply voltage several minutes to tens of minutes during, also can stably keep against distorted-structure.Liquid crystal molecule can use under contrary twist structured state, uses low voltage drive.

But, the liquid crystal molecule of patent documentation 3 records, sharpness (sharpness) (for the rapid property of the variation of the transmittance that applies voltage) is identical or slightly excellent with common TN type liquid crystal display cells, is difficult to make the capacity of display to become big problem being applied to exist under the situation that simple matrix drives.

Known bigger than the torsion angle in the TN type liquid crystal display cells relevant for the torsion angle of liquid crystal molecule is made, improve sharpness, be that simple matrix drives but can realize that supertwist that high capacity shows is to row (super twisted nematic simultaneously; STN) invention of type liquid crystal display cells (for example with reference to patent documentation 4).In the invention of patent documentation 4 record, for reply by the painted problem that double refraction causes, disclose that will compensate painted liquid crystal cells stacked, the method for realization white and black displays.

If but the using compensation unit, then the thickness of the manufacturing cost of liquid crystal cells and liquid crystal display cells and weight all will become about twice.

Use optical compensation films though can replace compensating unit, optical compensation films is not cheap.Have again, in the display environment temperature variation of liquid crystal display cells situation under, because even the delay of the liquid crystal layer in the driver element is followed this and is changed, the delay of optical compensation films also changes hardly, so can not carry out optimum compensation, exist and take place painted or the such problem of demonstration contrast reduction.

In the invention of patent documentation 4 records, also there is common problem in the STN type liquid crystal display cells in addition.The display performance of the liquid crystal display cells of STN type is for the interdependence height of the variation of the gap of liquid crystal cells or tilt angle, easily difference irregular owing to small element thickness or tilt angle show inhomogeneous.Therefore, the management strictness of manufacture process (it is little to make surplus), yield rate is low.In STN type liquid crystal display cells, need about 5～9 ° high tilt angle, obtain also difficulty of uniform tilt angle, especially the management of friction process is important.

Have, the visual angle interdependence that shows in the STN type liquid crystal display cells is big again, changes view directions minutely demonstration is changed, and particularly exists in to show the problem that counter-rotating is such when changing the visual angle on the above-below direction.In addition, STN type liquid crystal display cells is compared with TN type liquid crystal display cells, needs the response time.For example the response time of the TN type liquid crystal display cells under the room temperature is about 30msec, and the response time of STN type liquid crystal display cells is about 200msec.

Patent documentation 1: No. 2510150 communiques of Japan's special permission

Patent documentation 2: TOHKEMY 2000-199903 communique

Patent documentation 3: TOHKEMY 2007-293278 communique

Patent documentation 4: Japanese kokai publication hei 03-111812 communique

Summary of the invention

The purpose of this invention is to provide liquid crystal display cells with good sharpness.

According to first viewpoint of the present invention, a kind of liquid crystal display cells is provided, it has first substrate, and it has first electrode, has been carried out orientation process on first direction; Second substrate, its relative abreast configuration with above-mentioned first substrate has second electrode, has been carried out orientation process on second direction; And liquid crystal layer, it is configured between above-mentioned first substrate and above-mentioned second substrate, comprise chiral material, carry out twisted-oriented, above-mentioned second direction is the normal direction from above-mentioned first substrate-side, on first gyratory directions, become 70 °～110 ° direction with respect to above-mentioned first direction, the liquid crystal molecule of above-mentioned liquid crystal layer is along the above-mentioned first gyratory directions twisted arrangement, normal direction from above-mentioned first substrate-side, above-mentioned chiral material is along the turning quality that towards the direction of above-mentioned second substrate liquid crystal molecule of above-mentioned liquid crystal layer is given court's second gyratory directions opposite with above-mentioned first gyratory directions from above-mentioned first substrate, above-mentioned first substrate and above-mentioned second substrate are oriented to be processed into and manifest greater than 0 ° and smaller or equal to 5 ° pretilt theta, when the thickness of establishing above-mentioned liquid crystal layer is d, when the chirality spacing of above-mentioned chiral material is p, above-mentioned θ, above-mentioned d and above-mentioned p satisfy following formula (1) and (2)

$2\&le;\frac{p}{d}<4\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

According to the present invention, can provide liquid crystal display cells with good sharpness.

Description of drawings

Fig. 1 is the process flow diagram of manufacture method of the liquid crystal display cells of expression first embodiment.

Fig. 2 is the sectional view of summary of the liquid crystal display cells of expression first embodiment.

Fig. 3 is the splash distorted-structure state of liquid crystal display cells of expression first embodiment and the photo of contrary distorted-structure state.

Fig. 4 (A) and (B) be the chart of electric optical characteristics of the liquid crystal display cells of expression first embodiment.

Fig. 5 is the chart of the electric optical characteristics under the contrary aligned twisted state of liquid crystal display cells of expression second embodiment.

Fig. 6 is the chart of the electric optical characteristics under the contrary aligned twisted state of liquid crystal display cells of expression the 3rd embodiment.

Fig. 7 is the chart that the expression tilt angle is got the electric optical characteristics under 21 ° the contrary aligned twisted state of liquid crystal display cells.

Fig. 8 is the chart of mixing ratio with the relation of the tilt angle that manifests of two kinds of polyimide materials of expression.

Fig. 9 is the chart of the relation that applies voltage and transmittance under the contrary aligned twisted state of liquid crystal display cells of expression the 4th embodiment.

Figure 10 (A) to (C) is respectively the chart of the relation that applies voltage and transmittance under the contrary aligned twisted state of liquid crystal display cells of expression first～the 3rd comparative example.

Figure 11 gathers the boundary voltage of the liquid crystal display cells of representing first～the 4th embodiment and the table of the physics value of the liquid crystal material that uses in each liquid crystal display cells.

Figure 12 is the figure of an example of the waveform of the driving voltage that applies between upside ITO electrode 12a, downside ITO electrode 12b by power supply 20 of expression.

Figure 13 (A) and (B) be the chart of example that is illustrated in the scope of the pretilt theta of the sharpness of exhibit excellent in the contrary TN type liquid crystal display cells and p/d.

Label declaration

10a upside substrate

10b downside substrate

11a upside glass substrate

11b downside glass substrate

12a upside ITO electrode

12b downside ITO electrode

13a upside orientation film

13b downside alignment films

14 liquid crystal layers

The 14a liquid crystal molecule

15a upside polaroid

15b downside polaroid

20 power supplys

Embodiment

The liquid crystal display cells that following handle is put down in writing in patent documentation 3 calls contrary TN type liquid crystal display cells, it has a kind of liquid crystal layer, this liquid crystal layer is made into and makes the torsional direction of the liquid crystal material that has lured by the torsional direction of the liquid crystal material that combination determined of the orientation process direction of one group of alignment films and tilt angle with by optically active substance (chiral material) become rightabout mode, by apply voltage (electric field treatment) to liquid crystal layer, can realize contrary distortion (evenly distortion) structure and splash distorted-structure convertiblely.

Contrary TN type liquid crystal display cells is because can reduce the threshold value of driving voltage, so have the feature that can realize that low-power consumption drives.The present inventor is a purpose with the threshold value that reduces driving voltage, studies for the contrary TN type liquid crystal display cells of making under various conditions, and its achievement is open in patent documentation 3.The high more then contrary distorted-structure state of found that of present inventors' research, tilt angle is stable more, and the threshold value of the short more then driving voltage of chirality spacing of chiral material is low more, but contrary distorted-structure state is unstable more.

In patent documentation 3, having put down in writing with contrary distorted-structure state is that stable, high tilt angle condition is the achievement of the research carried out of center.Though also implemented experiment about low tilt angle condition, because contrary distorted-structure state is unsettled ordered state originally, so for the contrary more unsettled short spacing condition of distorted-structure state (the chirality spacing is less than 20 μ m) is studied.

The application's invention be about the so common research object of low tilt angle and short spacing condition outer, the unusual achievement in research of the contrary distorted-structure state under the non-steady state.Present inventors have found the phenomenon that is not expected to that the sharpness of liquid crystal display cells becomes very rapid under this special condition.Why such phenomenon can take place, and does not still understand now.In addition, even by simulation, the generation of such phenomenon is also unpredictable.

The application's invention is described according to embodiment below.

Fig. 1 is the process flow diagram of manufacture method of the liquid crystal display cells of expression first embodiment.

Prepare two and be formed with for example transparency carrier of ITO (indium tin oxide) film of nesa coating.Transparency carrier for example is the soda-lime glass formation of 0.7mmt with thickness.The thickness of ITO film for example is 1500A.These transparency carriers cleanings, dry (step S101), use photo-mask process to carry out the graphical of ITO film, go up formation transparency electrode (ITO electrode) (step S102) at transparency carrier (glass substrate).The etching of ITO electrode pattern is for example carried out the wet etching of ferric trichloride as the etching solution of major component to use.

The coating aligning film material is to cover ITO electrode (step S103) on glass substrate.The coating of aligning film material for example uses gentle version (flexo) printing to carry out.Also can use ink jet printing.As aligning film material, for example use the SE-130 of (share) daily output chemistry system.SE-130 is the horizontal alignment membrane material that manifests the TN type used for liquid crystal display element of low tilt angle.Aligning film material is not limited thereto.

The glass substrate that has been coated with aligning film material is placed on the hot plate, under 100 ℃, carries out 3 minutes false sintering (preliminary drying) (step S104).Cleaning stove in 200 ℃ under carry out 1 hour true sintering (step S105) thereafter.Form to cover alignment films (the step S103～S105) of ITO electrode like this.

Then carry out friction treatment (orientation process) (step S106).Friction treatment is to make to roll up the operation that the roller high speed rotating cylindraceous of cloth is arranged and rub on alignment films, can make thus with the liquid crystal molecule of substrate contacts and arrange (orientation) in one direction.

Constant for the thickness (distance between substrate) that keeps liquid crystal cells, use dry type to scatter method and on a glass substrate face, scatter gap control material (step S107).Gap control material uses the silicon based material ((share) Yu Bu Ri East changes into system Ha イ プ レ シ カ UF) of particle diameter 5 μ m.Also can use baton round.

Printing and sealing material on another glass substrate face forms main seal patterns (step S108).For example with the ES-7500 of silk screen print method printing as (share) Mitsui Chemicals system of thermosetting encapsulant.ES-7500 comprises the glass fibre of the particle diameter 5 μ m of a few percent.Also can use divider coating encapsulant in addition.In addition, also can use and be not thermosetting but the material of photo-hardening or photo-thermal and with the encapsulant of constrictive type.

On the real estate that has formed main seal patterns, include the conductive material that the baton round (Au ball) of having implemented golden plating waits, formation conductive material figure in the position printing of regulation.For example, the material of the Au ball about the particle diameter 6 μ m that comprise a few percent in ES-7500 is carried out serigraphy as conductive material.The printing of conductive material figure also can be carried out on the substrate different with the substrate that is printed with main seal patterns.

Bonding glass substrate (step S109).Two glass substrates are made a unit in the coincidence of the position of regulation, under the state of pressurization, implement thermal treatment and make sealing material curing.Here the arrangement of the liquid crystal molecule when two glass substrates are overlapped from upside substrate normal direction, makes and reverses 90 ° to right and make up like that.For example use pressure sintering,, carry out the thermmohardening of encapsulant at 150 ℃ of following sintering., use chalker on glass substrate form scar, disconnect, form rectangle along a part that forms scar thereafter.

Rectangular dummy cell after cutting apart as unit, is for example injected nematic liquid crystal (step S110) with vacuum impregnation in dummy cell.In liquid crystal material, for example use the RDP-84910 of (share) DIC system.In liquid crystal, add chiral material.Adjust addition, make the chirality spacing along becoming 15 μ m towards the direction of downside substrate in the left handed twist direction from the upside substrate.

For example using the end encapsulant encapsulated liquid crystals mouth (step S111) of ultraviolet ray (UV) sclerosis type, is the orientation of arrangement liquid crystal molecule, the unit is heated to more than the phase inversion temperature of liquid crystal (step S112).For example under 120 ℃, carry out 30 minutes thermal treatment by stove., along the remainder that use chalker on glass substrate form scar disconnect, cut into little other unit thereafter.

Implement chamfering (step S113) and clean (step S114) for cutting into little unit.In matting, by cleaning units such as clean-out system, organic solvents, the powder when washing the liquid crystal that on the unit, adheres to and chamfering off.

At last, with the face of the liquid crystal side opposition side of two glass substrates on paste the polaroid (step S115) that cuts into prescribed level.Two polaroids are configured to intersect Niccol, realize the TN type liquid crystal display cells of standard white, connect power supply between the ITO of two substrates electrode.

Fig. 2 is the sectional view of summary of the liquid crystal display cells of expression first embodiment.

The liquid crystal display cells of first embodiment comprises the twisted nematic liquid crystal layer 14 of relative in parallel to each other upside substrate 10a, downside substrate 10b that disposes and clamping between two substrates 10a, 10b and constitutes.

Upside substrate 10a comprises upside glass substrate 11a, at upside ITO electrode 12a that forms on the upside glass substrate 11a and the upside orientation film 13a that on upside ITO electrode 12a, forms.Equally, downside substrate 10b comprise downside glass substrate 11b, at downside ITO electrode 12b that forms on the downside glass substrate 11b and the downside alignment films 13b that on downside ITO electrode 12b, forms.

Liquid crystal layer 14 disposes between the downside alignment films 13b of the upside orientation film 13a of upside substrate 10a and downside substrate 10b.The thickness of liquid crystal layer 14 for example is 5 μ m.

On upside and downside alignment films 13a, 13b, implement orientation process by friction.The orientation process direction of upside orientation film 13a and downside alignment films 13b is mutually orthogonal.When the frictional direction of supposition upside orientation film 13a is the frictional direction of first direction, downside alignment films 13b when being second direction, second direction is from the normal direction of upside substrate 10a, for the first direction being the direction of 90 ° of the one-tenth of benchmark.Form at liquid crystal material under the situation of the even distortion that does not comprise the splash structure, more specifically say, for example do not comprise under the situation of liquid crystal material of chiral material, will become in combination conduct and on right, reverse 90 ° even twist structured combination by the direction direction (direction that liquid crystal molecule erects substrate) decision, that forms tilt angle of the friction treatment on the upside substrate and the direction of the tilt angle of downside substrate in the intermembranous configuration of respective orientation.In addition, the tilt angle of giving to upside and downside alignment films 13a, 13b is 1 °.

In liquid crystal layer 14, add chiral material.Addition is adjusted to and makes the chirality spacing become 15 μ m.From the normal direction of upside substrate 10a, the liquid crystal molecule 14a that produces owing to the influence power of chiral material is arranged as the splash distorted-structure that reverses in the left handed twist direction towards the direction of downside substrate 10b along from upside substrate 10a.

The torsional direction of liquid crystal molecule 14a under the liquid crystal cells completion status is the left handed twist (splash distorted-structure) identical with the torsional direction that causes by chiral material.

Between upside ITO electrode 12a, downside ITO electrode 12b, connect power supply 20.Between two electrode 12a, 12b, apply alternating voltage more than the threshold voltage by power supply 20, can make the arrangement of liquid crystal molecule 14a change (transfers) to evenly distortion (against twisting) structure thus from the splash distorted-structure.In addition, can use power supply 20 to drive liquid crystal display cells.

On upside substrate 10a, downside substrate 10b and faces liquid crystal layer 14 opposition sides, upside polaroid 15a, downside polaroid 15b are set respectively.Two polaroid 15a, 15b dispose to become intersection Niccol and the light transmission shaft mode parallel with the frictional direction of upside and downside substrate 10a, 10b.Therefore the liquid crystal display cells of this embodiment becomes the liquid crystal display cells of standard white type.

Fig. 3 is the splash distorted-structure state of liquid crystal display cells of expression first embodiment and the photo of contrary distorted-structure state.Photo is taken from the normal direction of the upside substrate 10a of the liquid crystal display cells of first embodiment.

As above-mentioned, the liquid crystal display cells of first embodiment can make the ordered state of liquid crystal molecule 14a transfer to contrary distorted-structure from the splash distorted-structure by apply the alternating voltage more than the threshold voltage between upside ITO electrode 12a, downside ITO electrode 12b.High more this transfer of the frequency of the voltage that applies takes place fast more.

Make the threshold voltage value that shifts generation exist with ... the kind of liquid crystal material and the addition of chiral material etc., but in the liquid crystal display cells of first embodiment, by the voltage more than the 7V was applied about 3 seconds, the ordered state of a part of liquid crystal molecule 14a on electrode 12a, the 12b is transferred to contrary distorted-structure.In addition, the voltage of 10V, 200Hz is applied 3 minutes, the structure of all liquid crystal molecule 14a on electrode 12a, the 12b is transferred to contrary distorted-structure as a result.In addition, experiment described later is to make structure transfer to the experiment of carrying out behind the contrary distorted-structure fully.

As shown in Figure 3, between splash aligned twisted state and contrary aligned twisted state, with the naked eye look there is not big difference.In addition, under any ordered state, can both carry out same good white demonstration.Though the torsional direction difference of the liquid crystal molecule of two ordered states all is a twisted nematic orientation, almost as broad as long under the situation of substrate normal direction observation unit.For example observe liquid crystal cells, under applying, can easily distinguish two ordered states than the high slightly voltage condition of the threshold voltage that generation is shifted from oblique direction.This is near the cause of 90 ° of direction (the best is looked and seen direction) the phase mutual deviations that erect of liquid crystal molecule the central authorities of thickness direction of liquid crystal cells.

When between two electrode 12a, the 12b of the liquid crystal display cells of first embodiment, applying the voltage of saturation voltage degree, under splash aligned twisted state and contrary two states of aligned twisted state, liquid crystal molecule 14a erects on the direction vertical with substrate 10a, 10b, can access good black demonstration.In addition, in each structure of two kinds of structures, when changing white demonstration of view and black the demonstration, the both almost shows counter-rotating, has the viewing angle characteristic than broad, and this point can be confirmed.In addition, when comparing with the splash distorted-structure, contrary twist structured visual angle is narrower slightly, but does not see big difference.

According to above-mentioned, the liquid crystal display cells of first embodiment does not all carry out special optical compensation under splash distorted-structure and contrary twist structured any state as can be known, can access good white black the demonstration.In addition, this point is not limited to first embodiment, about other embodiment too.

The liquid crystal display cells of first embodiment that transfers to contrary aligned twisted state is placed under the state that does not apply voltage, observed the situation that slowly turns back to the splash aligned twisted from contrary aligned twisted.The liquid crystal display cells of hence one can see that first embodiment is under the state that does not apply voltage, and to compare the splash aligned twisted in stable condition with contrary aligned twisted state.In addition, in the liquid crystal display cells of first embodiment, when the state continuance that does not apply voltage is about 2 minutes, take place from of the transfer again of contrary aligned twisted to the splash aligned twisted.But under the situation that keeps applying under the state of certain degree voltage, can keep contrary aligned twisted state for a long time.

Present inventors have measured the electric optical characteristics of the liquid crystal display cells of first embodiment.Fig. 4 (A), (B) represent its result.The relation that applies voltage and transmittance under Fig. 4 (A) expression splash aligned twisted state, the relation that applies voltage and transmittance under the contrary aligned twisted state of Fig. 4 (B) expression.The transverse axis of two picture in picture tables is illustrated in the voltage that applies between electrode 12a, the 12b with unit " V ", and the longitudinal axis is with the transmittance of unit " % " expression liquid crystal display cells.So-called printing opacity refers to pass through to opposite side from the light of side's side incident of polaroid 15a, 15b.

Sharpness under splash aligned twisted state and contrary aligned twisted state (with respect to the rapid property of the variation of the transmittance that applies voltage) is obviously different, shown in Fig. 4 (B), as can be known under contrary aligned twisted state with respect to the rapid property big (sharpness is excellent) of the variation of the transmittance that applies voltage.

Under splash aligned twisted state and contrary each state of aligned twisted state,, V10/V90 and V5/V90 have been calculated as definition values.Here, V5, V10, V90 be respectively the brightest transmittance as 100% o'clock, can access the magnitude of voltage of 5% transmittance, 10% transmittance, 90% transmittance.Result calculated is tried to achieve under splash aligned twisted state V10/V90=1.746, V5/V90=1.987; Under contrary aligned twisted state, the definition values that V10/V90=1.037, V5/V90=1.041 are such.

For the needed definition values of dutycycle driving liquid crystal display cells with 1/480 is below 1.0465.The liquid crystal display cells of first embodiment V10/V90, V5/V90 under contrary aligned twisted state can both realize this desired value.That is the liquid crystal display cells of first embodiment can use contrary aligned twisted state to carry out 1/480 the such high duty ratio driving of dutycycle driving.

On the other hand, be below 1.447 for the needed definition values of dutycycle driving liquid crystal display cells with 1/8.The liquid crystal display cells of first embodiment V10/V90, V5/V90 under splash aligned twisted state can not realize this desired value.Even that is the demonstration of using splash aligned twisted state under the situation that the dutycycle of carrying out 1/8 drives, can not become clear as can be known

In addition, drive in (simple matrix driving) in dutycycle, establishing number of scanning lines is that N, forward voltage are V _On, shutoff voltage is V _OffThe time, their relation is represented with following formula (1).

$V_{\mathrm{on}}=\sqrt{\frac{\sqrt{N}+1}{\sqrt{N}-1}}{V}_{\mathrm{off}}\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

The liquid crystal display cells of second embodiment is described.The liquid crystal material that second embodiment uses is different with first embodiment.In a second embodiment, use the RDR-83107 of (share) DIC system to constitute liquid crystal layer as nematic liquid crystal material.The kind of the chiral material that adds in the liquid crystal and addition equate with the situation of first embodiment.That is chirality spacing edge is 15 μ ms towards the direction of downside substrate in the left handed twist direction from the upside substrate.

Fig. 5 is the chart of the electric optical characteristics under the contrary aligned twisted state of liquid crystal display cells of expression second embodiment.The voltage of the transverse axis of chart to apply between unit " V " expression electrode, the longitudinal axis is with the transmittance of unit " % " expression liquid crystal display cells.Make the liquid crystal display cells of two second embodiment, apply the relation of voltage and transmittance at both researchs.

As can be known the liquid crystal display cells of second embodiment also and the situation of first embodiment of Fig. 4 (B) expression same, sharpness is good.In addition we know, the individual difference that applies voltage-transmittance characteristic is little, for the surplus broad of unit condition.

The liquid crystal display cells of the 3rd embodiment is described.The liquid crystal material that the 3rd embodiment uses is different with first and second embodiment.In the 3rd embodiment, use the RDR-83108 of (share) DIC system to constitute liquid crystal layer as nematic liquid crystal material.The kind of the chiral material that adds in the liquid crystal and addition equate with the situation of first and second embodiment.Chirality spacing edge is 15 μ ms towards the direction of downside substrate in the left handed twist direction from the upside substrate.

Fig. 6 is the chart of the electric optical characteristics under the contrary aligned twisted state of liquid crystal display cells of expression the 3rd embodiment.The voltage of the transverse axis of chart to apply between unit " V " expression electrode, the longitudinal axis is with the transmittance of unit " % " expression liquid crystal display cells.Present inventors have made the liquid crystal display cells of four the 3rd embodiment, apply the relation of voltage and transmittance at each element research.

As can be known the liquid crystal display cells of the 3rd embodiment also and the situation of second embodiment that represents of first embodiment, Fig. 5 of Fig. 4 (B) expression same, sharpness is good.In addition we know, the individual difference that applies voltage-transmittance characteristic in the 3rd embodiment is also little, for the surplus broad of unit condition.

In the liquid crystal display cells of first～the 3rd embodiment, thickness (element thickness) d that establishes liquid crystal layer 14 is 5 μ m, and chirality spacing p is 15 μ m.The value of d/p is 1/3.Element thickness d is not limited to 5 μ m.The amount that preferably is used in the chiral material that adds in the liquid crystal is adjusted the value of d/p.

In addition, under the situation of TN type liquid crystal display cells, be the demonstration that obtains becoming clear, the transmittance T when the standard black of expression TN type liquid crystal cells _NBGucci-Terry (グ Star チ テ リ-) formula in, need to satisfy first minimum or second minimal condition.The Gucci-Terry formula is represented with following formula (2).

$T_{\mathrm{NB}}=\frac{{\sin }^2\left\{(\mathrm{\&pi;}/2)\sqrt{1+u^2}\right\}}{1+{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="HSA00000452367100041.png,HSA00000452367100061.png"\; state="\{\{state\}\}">u</figure-callout>}}^2}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

In the formula, u is the value of calculating with following formula (3).

$u=\frac{2\mathrm{\&Delta;nd}}{\mathrm{\&lambda;}}\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

In the formula (3), Δ n is the refractive index anisotropy of liquid crystal, and λ is the light wavelength that incides liquid crystal cells, in addition d such as above-mentioned expression element thickness.

For satisfying first minimum or second minimal condition of Gucci-Terry formula, preferably select liquid crystal material (the refractive index anisotropy Δ n of liquid crystal) according to element thickness d.For example when element thickness d is reduced, increase the value of refractive index anisotropy Δ n, otherwise, when element thickness d is increased, reduce the value of refractive index anisotropy Δ n, select liquid crystal material in such a way.

In addition, because think that element thickness d is more little, the ordered state of liquid crystal molecule is stipulated consumingly by the combination of orientation process direction and tilt angle more, so the little liquid crystal display cells of presumption units thickness d can stably keep contrary aligned twisted state.

As shown in embodiment, the value that preferably makes d/p be 1/3 or its near value.Even but think that how many its values has change, and also can play same effect.Along with the value increase of d/p, the influence of chiral material manifests consumingly, and splash aligned twisted state stably exists easily.Its result is produced as and makes the needed threshold voltage rising from splash aligned twisted state transitions to contrary aligned twisted state, the stable simultaneously tendency that shortens against the time of aligned twisted state that remains on.Therefore, the value of preferred d/p is substantially below 1/2.Think that on the other hand along with the value of d/p diminishes, the distortion that produces in the liquid crystal layer that is given by chiral material also diminishes the tendency of sharpness variation.The addition of chiral material is many, and promptly chirality spacing p is desirable for a short time.The value of preferred d/p is bigger than 1/2 substantially.

In the liquid crystal display cells of first～the 3rd embodiment, the aligning film material that low tilt angle is manifested forms alignment films.Present inventors have made a kind of liquid crystal display cells for comparison purpose, and it only compares the aligning film material that uses and give the tilt angle of alignment films different with first embodiment.In aligning film material, use the material that shows higher tilt angle, give 21 ° tilt angle for the alignment films that forms.

Fig. 7 is the chart that the expression tilt angle is got the electric optical characteristics under 21 ° the contrary aligned twisted state of liquid crystal display cells.The voltage of the transverse axis of chart to apply between unit " V " expression electrode, the longitudinal axis is with the transmittance of unit " % " expression liquid crystal display cells.Make four liquid crystal display cells of giving 21 ° of tilt angles, applied the relation of voltage and transmittance at each element research.

Four liquid crystal display cells that tilt angle is 21 ° have individual difference, but the threshold value of all driving voltages is all low.But can't see good sharpness such shown in Fig. 4 (B).The result who represents from Fig. 7 thinks that for realizing good sharpness, the preferred aligning film material that manifests low tilt angle that uses forms alignment films, implements the orientation process of giving low tilt angle for the alignment films that forms.

The present inventor studies about the sharpness of contrary TN type liquid crystal display cells and the relation of tilt angle.The controlled of tilt angle at first is described.Present inventors confirm, are used in two kinds of alignment films of mixing polyimide material formation of having added the polyimide material ((share) チ Star ソ petrochemistry system PIA-359-01X) that shows low tilt angle in the polyimide material ((share) チ Star ソ petrochemistry system PIA-768-01X) that shows high tilt angle and having obtained and can manifest tilt angle continuously.

Fig. 8 is the chart of mixing ratio with the relation of the tilt angle that manifests of two kinds of polyimide materials of expression.The transverse axis of chart mixes containing than (concentration) of PIA-768-01X in the polyimide material with unit " % " expression, the longitudinal axis with unit " ° " size of the tilt angle that manifests of expression.When measuring tilt angle, use the liquid crystal material ZLI4792 of (share) メ Le Network system.As can be known, tilt angle increases with the ratio that contains of polyimide material PIA-768-01X with being directly proportional from this figure.Therefore, by adjusting the mixing ratio of polyimide material PIA-768-01X and PIA-359-01X, can realize the successive control of the tilt angle that manifests.

The following describes the liquid crystal display cells of the 4th embodiment and first～the 3rd comparative example.The 4th embodiment is the liquid crystal display cells that has formed alignment films with the mixing polyimide material that the mixing ratio of alignment film of polyimide material PIA-768-01X and PIA-359-01X was got 20: 80, and first～the 3rd comparative example is to have that mixing ratio was got 45: 55,40: 60,30: 70 and the liquid crystal display cells of the alignment films that forms successively.

The used for liquid crystal display element of the 4th embodiment and the same method manufacturing of manufacture method that illustrates with reference to Fig. 1.Difference and additional details are as follows.

In a pair of length of side is on the foursquare glass substrate (thickness 1.1mm) of 2cm, forms the length of side and is the foursquare ITO electrode of 1cm and be used to make it and the peripheral electrode of outside conducting.When forming alignment films, the alignment films polyimide material of the about 0.1 μ m of coating thickness on glass substrate, this alignment films polyimide material mixes with the PIA-359-01X ratio of 20% (share) チ Star ソ petrochemistry system PIA-768-01X and 80%.In friction treatment, use the cut velvet cloth of kapok system.When pasting a pair of glass substrate, frictional direction is got mutually orthogonal direction.Specifically, the frictional direction of upside orientation film as first direction, the frictional direction of downside alignment films during as second direction, second direction be first direction as benchmark, regard 90 ° direction as from the normal direction of upside substrate.Do not comprise the splash structure at liquid crystal material, more specifically say, for example under the situation that has disposed the liquid crystal material that does not comprise chiral material between this alignment films, will by the tilt angle of the direction that direction determined, that tilt angle forms (direction that liquid crystal molecule erects with respect to substrate) of the friction treatment of upside substrate and downside substrate towards combination as the combination that becomes the homogeneous texture of on right, reversing 90 °.

On the alignment films of a glass substrate, after distribution changes into system HIPRESICA (Ha イ プ レ シ カ) UF as (share) Yu Bu Ri East of the silicon system gap control material of diameter 5 μ m, periphery coating epoxy at glass substrate is an encapsulant, and heating made its sclerosis in 1 hour under 150 ℃ temperature.Make inlet and the exhausr port that is used to inject liquid crystal material at hermetic unit.

The dummy cell of preparing like this is placed on the hot plate, utilizes capillarity that liquid-crystal composition is injected in the space that fences up with encapsulant from inlet.Liquid crystal material uses the RDP-83409 of (share) DIC system.In liquid crystal, add chiral material.Adjusting addition makes the chirality spacing along becoming 15 μ ms towards the direction of downside substrate at right torsional direction from the upside substrate.After the injection of liquid-crystal composition finished, the configuration epoxy was a bonding agent on inlet and exhausr port, placed to make the sclerosis sealing on the 1st.With the state of orientation of polarized light microscope observing liquid crystal, confirm to have obtained whole uniform state of orientation.In addition, with (result that the liquid crystal cell tilt angle determinator PAS-001 of share) East Yang テ Network ニ Network system measures is that the tilt angle that alignment films is given is about 5 °.

Apply voltage-transmittance characteristic by what confirm this state, observe the driving voltage threshold value higher, distinguish to have formed the twist structured liquid crystal cell of splash than common TN type liquid crystal display cells.In addition, between the electrode of this liquid crystal cell, apply the square-wave voltage of 10V, make liquid crystal molecule keep the state of homeotropic alignment substantially, thereby in the tone of liquid crystal molecule, find to change with respect to substrate.The variation of tone produces partly, and the part that tone changes slowly enlarges, and expands to whole during several minutes.In the zone that tone changes, think and taken place from of the transfer of splash aligned twisted state to contrary aligned twisted state.Contrary aligned twisted state also exists between tens of seconds after stopping to apply voltage, but transfers to splash aligned twisted state afterwards again.

Fig. 9 is the chart of the relation that applies voltage and transmittance under the contrary aligned twisted state of liquid crystal display cells of expression the 4th embodiment.The voltage of the transverse axis of chart to apply between unit " V " expression electrode, the longitudinal axis is with the transmittance of unit " % " expression liquid crystal display cells.Present inventors have made the liquid crystal display cells of four the 4th embodiment, have studied the relation that applies voltage and transmittance at each element.In mensuration, use (the LCD5200 as the electric optical characteristics determinator of liquid crystal cell of share) Da mound Electricity system.

In one in 4 liquid crystal display cells making, can find out that Fig. 4 (B), Fig. 5 and Fig. 6 represent, with the same good sharpness of first～the 3rd embodiment, in remaining 3, can't see.Think thus in contrary TN type liquid crystal display cells, the good property of sharpness does not change continuously according to tilt angle, and be the boundary with 5 ° of such tilt angles, the tilt angle that gives upper and lower base plate all greater than 0 ° and smaller or equal to 5 ° of such conditions under manifest the good property of sharpness.

Figure 10 (A) represents the relation that applies voltage and transmittance under the contrary aligned twisted state of liquid crystal display cells of first～the 3rd comparative example respectively to (C).As above-mentioned, first～the 3rd comparative example is the liquid crystal display cells that has formed alignment films with the mixing polyimide material that the mixing ratio of alignment film of polyimide material PIA-768-01X and PIA-359-01X was got 45: 55,40: 60,30: 70.The liquid crystal display cells of first～the 3rd comparative example is used the direction manufacturing that equates with the 4th embodiment except different these points of mixing ratio of aligning film material.In addition, about each comparative example, make a plurality of liquid crystal cells.The transverse axis of the chart of Figure 10 (A)～(C) is with the voltage that applies between unit " V " expression electrode, and the longitudinal axis is with the transmittance of unit " % " expression liquid crystal display cells.

Judge according to the chart of Fig. 8, think that the tilt angle of first comparative example (mixing ratio 45: 55) of the electric optical characteristics of expression is 15 ° strong among Figure 10 (A).Think that in addition Figure 10 (B), second comparative example (mixing ratio 40: 60) of the electric optical characteristics of (C) middle expression, the tilt angle of the 3rd comparative example (mixing ratio 30: 70) are respectively a little less than in the of 15 ° and 7～8 °.

From the result of Figure 10 (A) to (C) expression as can be known, in first～the 3rd comparative example, can't see the good property of the sharpness under the contrary aligned twisted state.In addition, the good property of yet having reaffirmed sharpness is not according to the tilt angle continually varying.

As above-mentioned, good sharpness characteristic tilt angle greater than 0 ° and smaller or equal to 5 ° of such conditions under manifest.Such as has been described in addition, the ratio d/p of the thickness d of preferred liquid crystal layer and the chirality spacing p of chiral material is greater than 1/4 and smaller or equal to 1/2.

Present inventors have made thickness d=5 μ m, chirality spacing p=20 μ m, d/p=1/4, pretilt theta=5 ° contrary TN type liquid crystal display cells of thickness d=5 μ m, chirality spacing p=20 μ m, d/p=1/4, pretilt theta=1 ° contrary TN type liquid crystal display cells of liquid crystal layer and liquid crystal layer, the electric optical characteristics under the contrary aligned twisted state of research.Its result can't see the such good sharpness of seeing among the embodiment.Think that thus more than 1 ° below 5 ° the time, d/p is in order to obtain the good necessary condition of sharpness characteristic greater than 1/4 at tilt angle.

The contrary TN type liquid crystal display cells of embodiment is the former state maintenance can not want optical compensation plate and obtain white black demonstration, can easily make by enough low costs, the visual angle broad, respond the advantage of the such TN type liquid crystal display cells of high speed, and can realize the liquid crystal display cells of good sharpness.Because sharpness is good, so for example can enough big capacities of display show under the situation that simple matrix drives carrying out.

In addition, because be the liquid crystal display cells of low tilt angle,, be liquid crystal display cells therefore with high reliability so can use the TN type used for liquid crystal display element aligning film material manufacturing of widely used high reliability in industry.

Have, the liquid crystal display cells of embodiment can drive with 1/480 dutycycle again.In simple matrix drove, 1/480 dutycycle drove the driving that is to use high duty ratio number.Therefore applied range for example can utilize in the liquid crystal display cells that nearly all simple matrix drives.

In addition, the number of electrodes of (upside ITO electrode 12a, downside ITO electrode 12b either party) is many because good sharpness characteristic public electrode, for example can make more than 100, can show by enough high display performances.

Figure 11 gathers the boundary voltage of the liquid crystal display cells of representing first～the 4th embodiment and the table of the physics value of the liquid crystal material that uses in each liquid crystal display cells.V in the table _cThe measured value of representing the boundary voltage of liquid crystal display cells with unit " V ".So-called boundary voltage, refer to slowly reduce the liquid crystal display cells that is under the contrary aligned twisted state apply voltage the time, return to the voltage of splash aligned twisted state.Δ _εThe dielectric constant anisotropy of expression liquid crystal material.In addition, K ₁₁, K ₂₂, K ₃₃Extension elastic constant, elasticity of torsion constant, the bend elastic constant of representing liquid crystal material respectively with unit " pN ".Have, γ 1 is with the rotary viscosity of unit " mPas " expression liquid crystal material again.

Boundary voltage V _cMore little liquid crystal display cells is stable more under contrary aligned twisted state.Therefore, in the contrary making of TN type liquid crystal display cells, preferred selection makes boundary voltage V _cLittle liquid crystal material or cellular construction.

In addition, the result of present inventors' research knows in the contrary TN type liquid crystal display cells of embodiment K ₁₁Value K when getting over Datong District ₂₂Value more little, the stability of contrary aligned twisted state is high more.From the viewpoint of the stability of contrary aligned twisted state, preferably use extension elastic constant K ₁₁With elasticity of torsion constant K ₂₂Ratio " K ₁₁/ K ₂₂" be the liquid crystal material formation liquid crystal layer more than 2.

The feature of the liquid crystal display cells of the physics value explanation embodiment in the table that use Figure 11 represents.Following formula (4) is that to calculate tilt angle be 0 the general contrary TN type liquid crystal display cells threshold voltage V at the driving voltage under the aligned twisted state _ThFormula.

$V_{\mathrm{th}}=\mathrm{\&pi;}\sqrt{\frac{K}{{\mathrm{\&epsiv;}}_0\left|\mathrm{\&Delta;\&epsiv;}\right|}}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

ε in formula (4) ₀The specific inductive capacity (8.85418782 * 10 of expression vacuum ^-12F/m).K is to be to be the value of calculating with following formula (5) under 90 ° the situation of contrary TN type liquid crystal display cells at twist angle in addition.

$K=k_{11}+\frac{1}{4}(K_{33}-2K_{22})\&CenterDot;\&CenterDot;\&CenterDot;\left(5\right)$

When general tilt angle was 0 °, the threshold value of driving voltage became maximum.That is tilt angle is not the magnitude of voltage V that the threshold ratio of driving voltage of 0 ° contrary TN type liquid crystal display cells is tried to achieve with formula (4) and formula (5) _ThLittle.Therefore, for example the threshold value of the driving voltage of the liquid crystal display cells of first～the 4th embodiment should compare V _ThLittle.

With reference to the table of Figure 11, physics value substitution (4) and (5) of the liquid crystal material of the liquid crystal layer of the liquid crystal display cells that constitutes first～the 4th embodiment, following calculating V _Th

Under the situation of RDP84910 (first embodiment), V _Th≒ 0.62V.

Under the situation of RDP83107 (second embodiment), V _Th≒ 0.89V.

Under the situation of RDP83108 (the 3rd embodiment), V _Th≒ 0.89V.

Under the situation of RDP83409 (the 4th embodiment), V _Th≒ 0.98V.

But when with reference to Fig. 4 (B), (switching voltage: be 1.2～1.3V the magnitude of voltage that transmittance begins to change when applying voltage), this is V to the threshold value of the driving voltage of the liquid crystal display cells of first embodiment _ThAbout 2 times of ≒ 0.62V.In addition, when reference Fig. 5, the threshold value of the driving voltage of the liquid crystal display cells of second embodiment is about 1.8V, is V _ThAbout 2 times of ≒ 0.89V.And then when reference Fig. 6, the threshold value of the driving voltage of the liquid crystal display cells of the 3rd embodiment is 1.5～1.7V, and this surpasses V _Th1.5 times of ≒ 0.89V.In addition, when reference Fig. 9, the threshold value of the driving voltage of the liquid crystal display cells of the 4th embodiment is 1.3～1.5V.This is V _ThMore than 1.3 times of ≒ 0.98V.Like this, the liquid crystal display cells of embodiment has the threshold voltage V that tries to achieve with formula (4) and formula (5) _ThThe threshold value of the big driving voltage more than 1.3 times.

Figure 12 represents an example of the waveform of the driving voltage that applies by power supply 20 between upside ITO electrode 12a, downside ITO electrode 12b.The transverse axis express time of figure, the longitudinal axis is represented magnitude of voltage." select waveform Vs " and be illustrated in the driving voltage waveform that applies on the selection pixel, " non-selection waveform Vus " is illustrated in the driving voltage waveform that applies on the non-selection pixel.

When driving the liquid crystal display cells of embodiment, moment is not only being selected pixel but also for example applying the ratio higher voltage that illustrates such waveform by some cycles on non-selection pixel.Therefore, in the liquid crystal display cells of embodiment, at first between two electrode 12a, 12b, apply the voltage more than the threshold voltage, after the ordered state that makes liquid crystal molecule 14a is transferred to contrary aligned twisted from the splash arrangement, drive if carry out common dutycycle, then can not apply transfer voltage for a long time and continue to show.At this moment, because show that with high more dutycycle driving then the crest voltage value is high more, so think that contrary aligned twisted state is more stable.From this viewpoint, the liquid crystal display cells of preferred embodiment drive condition that simple matrix is driven is taken as the dutycycle higher than 1/120 dutycycle and drives.

At last, about the reason of the sharpness of exhibit excellent under the contrary contrary aligned twisted state of TN type liquid crystal display cells, record and narrate the opinion of present inventors' hypothesis.

For example about contrary TN type liquid crystal display cells in patent documentation 3 record of first to file as present inventors, transmittance during from simulation or voltage shutoff etc. is known, under contrary aligned twisted state, even when voltage turn-offs, near the liquid crystal molecule the central authorities of the thickness direction of liquid crystal layer is by inside distortion the becoming state that erects slightly.If the threshold value of the driving voltage of contrary TN type liquid crystal display cells is low is because this state can think that then for making liquid crystal molecule vertically erect needed voltage little substantially be passable cause on substrate.In addition, in the contrary TN type liquid crystal display cells (standard white type) of patent documentation 3 records, though know that the transmittance when transmittance when voltage turn-offs under contrary aligned twisted state turn-offs than voltage under splash aligned twisted state is low, think that this also is because near the liquid crystal molecule of central authorities of the thickness direction of liquid crystal layer becomes the cause of the state that erects slightly when voltage turn-offs.

But, when reference example relatively during as Fig. 4 (A) of the electric optical characteristics of the liquid crystal display cells of representing first embodiment, (B), the transmittance the when transmittance during the following voltage shutoff of contrary aligned twisted state turn-offs than the voltage under the splash aligned twisted state is big on the contrary.In addition, even, also be that contrary aligned twisted state is big about the threshold value of driving voltage (applying when transmittance begins to reduce voltage).

From these true suppositions, in the liquid crystal display cells of embodiment, when voltage turn-offs under contrary aligned twisted state, although big distortion should be arranged in liquid crystal layer inside, near the central authorities of thickness of liquid crystal layer direction liquid crystal molecule erects hardly, and is parallel-oriented with real estate substantially.Apply under the voltage condition at the liquid crystal display cells of giving embodiment then, think because near the liquid crystal molecule the thickness of liquid crystal layer direction central authorities erects hardly, so when not applying high voltage to certain degree, liquid crystal molecule does not tilt to direction of an electric field, even but begin a little to tilt, by the big electric field that distorts than repressed inside, the variation of the direction of liquid crystal directors sharply takes place, by small voltage difference, near the thickness of liquid crystal layer direction central authorities liquid crystal molecule just almost vertically erects, and realizes good sharpness thus.

Yet although in liquid crystal layer inside big distortion should be arranged, the reason that near the liquid crystal molecule the thickness of liquid crystal layer direction central authorities erects hardly is also indeterminate.Think that the value etc. of elastic constant of the liquid crystal material that causes that with interpolation by chiral material the tilt angle that has big distortion in the liquid crystal layer, gives alignment films is little, form liquid crystal layer is relevant.

In addition, according to the observation, under the contrary contrary aligned twisted state of TN type liquid crystal display cells, at pretilt theta and p/d (p: chirality spacing, d: ratio element thickness) " θ/(p/d) " than under the big situation of certain value, under the state that does not apply voltage, manifest the phenomenon that near the liquid crystal molecule the thickness direction central authorities of liquid crystal layer erects.According to present inventors' research, at θ/(p/d) during, can observe near erecting of the liquid crystal molecule thickness direction central authorities of liquid crystal layer than 2 ° big.Therefore, satisfy in the chart of the relation that applies voltage and transmittance of contrary TN type liquid crystal display cells of this condition in expression, cannot see threshold property, transmittance begins to change from 0V.

On the other hand, at θ/(p/d) below 2 ° the time, under the state that does not apply voltage, do not observe the phenomenon that near the liquid crystal molecule the thickness direction central authorities of liquid crystal layer erects, in applying the chart of relation of voltage and transmittance, expression sees rapid threshold property.That is under the condition of following formula (6), the sharpness of exhibit excellent.

In the formula,

$\frac{1}{4}<\frac{d}{p}\&le;\frac{1}{2}\&DoubleLeftRightArrow;2\&le;\frac{p}{d}<4\&CenterDot;\&CenterDot;\&CenterDot;\left(7\right)$

0°＜θ≤5°…(8)

Figure 13 (A) and (B) be the chart of example that is illustrated in the scope of pretilt theta that sharpness good in the contrary TN type liquid crystal display cells occurs and p/d.In two charts, transverse axis is represented p/d, the longitudinal axis with unit " ° " expression pretilt theta.(borderline region comprises solid line portion, does not comprise dotted line part to draw the zone that oblique line is arranged.Do not comprise in addition and draw the point that white circle is arranged.) satisfy formula (6) to (8).

The straight line I of Figure 13 (A) _A, Figure 13 (B) straight line I _BAll be that degree of tilt is 2 straight line.That is, straight line I _A, I _BBe included in the straight line group with following formula (9) expression.

$\mathrm{\&theta;}=2\left(\frac{p}{d}\right)+\mathrm{\&beta;}\&CenterDot;\&CenterDot;\&CenterDot;\left(9\right)$

In formula (9), β is the constant that exists with ... liquid crystal material.Straight line I at Figure 13 (A) _AMiddle β=-1 is at the straight line I of Figure 13 (B) _BMiddle β=1.At Figure 13 (A) and the situation of β=± 1 (B), but according to the liquid crystal material that in contrary TN type liquid crystal display cells, uses, θ gets the value beyond this, and the degree of tilt of delimiting the zone (combination of θ and p/d) that fine details occur in this liquid crystal display cells is 2 straight line lifting.Therefore, realize that the scope of combination of the θ of good sharpness and p/d is also according to liquid crystal material and different.

According to embodiment the present invention has been described to this, but has the invention is not restricted to this.

For example, in an embodiment, the twist angle under the contrary aligned twisted state is got 90 °, but also can change in the scope about ± 20 ° (70 °～110 °).But when considering the lightness of white demonstration, preferably get 90 ° or near the twist angle it.

In addition, in an embodiment, an angle that forms that sees through of upside polaroid and downside polaroid is got 90 ° (Niccol that intersects disposes), but the angle that forms through axle of two polaroids can change in the scope about ± 5 °.But, preferably dispose with 90 ° or near it angle from preventing that the angle that light leaked from considering.In addition, polaroid is configured to the parallel polarization sheet, also can be used as the liquid crystal display cells of standard black type.In the sort of occasion, can make a scope of for example getting below 20 ° dispose polaroid through the angle of axle formation.

In addition, the professional is clear can carry out various changes, improvement, combination etc.

Liquid crystal display cells generally can utilize in liquid crystal display cells at OA equipment such as the vehicle mounted liquid crystal display cells that carries out various demonstrations such as audio frequency demonstration, thermal control demonstration, duplicating machine.In addition, the liquid crystal display cells that can drive at simple matrix particularly requires to utilize in the liquid crystal display cells under the situation of the big capacity of display.

Claims (7)

1. liquid crystal display cells, it has:

First substrate, it has first electrode, has been carried out orientation process on first direction;

Second substrate, its relative abreast configuration with above-mentioned first substrate has second electrode, has been carried out orientation process on second direction; With

Liquid crystal layer, it is configured between above-mentioned first substrate and above-mentioned second substrate, comprises chiral material, carries out twisted-oriented,

Above-mentioned second direction is the normal direction from above-mentioned first substrate-side, becomes 70 °～110 ° direction with respect to above-mentioned first direction on first gyratory directions,

The liquid crystal molecule of above-mentioned liquid crystal layer is along the above-mentioned first gyratory directions twisted arrangement,

From the normal direction of above-mentioned first substrate-side, above-mentioned chiral material is along giving towards the turning quality of second gyratory directions opposite with above-mentioned first gyratory directions towards the direction of above-mentioned second substrate liquid crystal molecule to above-mentioned liquid crystal layer from above-mentioned first substrate,

Above-mentioned first substrate and above-mentioned second substrate are oriented to be processed into and manifest greater than 0 ° and smaller or equal to 5 ° pretilt theta,

When the thickness of establishing above-mentioned liquid crystal layer is the chirality spacing of d, above-mentioned chiral material when being p, above-mentioned θ, above-mentioned d and above-mentioned p satisfy following formula (1) and (2),

$2\&le;\frac{p}{d}<4\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

2. liquid crystal display cells according to claim 1, wherein,

When the extension elastic constant of establishing the liquid crystal material that constitutes above-mentioned liquid crystal layer is K ₁₁, elasticity of torsion constant is K ₂₂The time, above-mentioned K ₁₁With above-mentioned K ₂₂Satisfy following formula (3),

$\frac{K_{11}}{K_{22}}\&GreaterEqual;2\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right).$

3. liquid crystal display cells according to claim 1, wherein,

Above-mentioned second direction is the normal direction from above-mentioned first substrate-side, becomes 90 ° direction on above-mentioned first gyratory directions with respect to above-mentioned first direction.

4. liquid crystal display cells according to claim 1, wherein,

Above-mentioned first substrate and above-mentioned second substrate are oriented to be processed into and manifest the pretilt theta below 5 ° more than 1 °.

5. liquid crystal display cells according to claim 1, wherein,

Above-mentioned second electrode is a public electrode, and the number of electrodes of above-mentioned public electrode is more than 100.

6. liquid crystal display cells according to claim 1, wherein,

Above-mentioned liquid crystal display cells also comprises:

Be configured in above-mentioned first substrate above-mentioned liquid crystal layer opposition side first polaroid and

Be configured in second polaroid of opposition side of the above-mentioned liquid crystal layer of above-mentioned second substrate,

The voltage of above-mentioned liquid crystal layer by applying between above-mentioned first electrode and above-mentioned second electrode is created on even distorted-structure that reverses on above-mentioned first gyratory directions and the splash distorted-structure that reverses convertiblely on above-mentioned second gyratory directions,

In above-mentioned even distorted-structure, when applying voltage between above-mentioned first electrode and above-mentioned second electrode, it is magnitude of voltage V that the light of the side's side incident from above-mentioned first polaroid, above-mentioned second polaroid passes through to the magnitude of voltage that the amount of the opposing party's side begins to change _ThMore than 1.3 times, above-mentioned magnitude of voltage V _ThBe to be K at the elasticity of flexure coefficient of establishing the liquid crystal material that constitutes above-mentioned liquid crystal layer ₃₃, dielectric constant anisotropy is that the specific inductive capacity of Δ ε, vacuum is ε ₀The time with following formula (4) and (5) trying to achieve,

$V_{\mathrm{th}}=\mathrm{\&pi;}\sqrt{\frac{K}{{\mathrm{\&epsiv;}}_0\left|\mathrm{\&Delta;\&epsiv;}\right|}}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

$K=K_{11}+\frac{1}{4}(K_{33}-2K_{22})\&CenterDot;\&CenterDot;\&CenterDot;\left(5\right).$

7. liquid crystal display cells according to claim 1, wherein,

The drive condition of simple matrix driving is made as the duty higher than 1/120 dutycycle recently to be driven.

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