EP1881258A1 - Lamp unit with a LED with integrated light deflection body - Google Patents

Abstract

The lighting unit has a non glowing light source (21) comprising illuminating diode and has an optical light distribution body downstream to the light source. The distribution body is a part of the illuminating diode. The section of the distribution body adjacent to the light source has an elliptical section as envelope in a section plane, which has the optical axis. A semi-major axis (36) of the ellipse is arranged in the zero degree direction shifted from the light source and that the radius of the osculation circle of the semi-major axis averages between 30 percent and 90 percent.

Description

The invention relates to a lighting unit comprising a light emitting diode comprising at least one non-glimmering light source and light distribution body optically connected to a non-glimmering light source, wherein the light distribution body has at least two sections arranged one behind the other in a zero-degree direction oriented at least approximately parallel to the optical axis of the lighting unit the end face of the light distribution body facing away from the non-glimmering light source has a depression and wherein each boundary surface of the depression comprises a total reflection surface for the light emitted by the non-glimmering light source.

The optical axis of a lighting unit is, for example, the geometric center line of the light emitted by the lighting unit. In a polar light distribution diagram for the lighting unit, the light source is arranged in the center. Around the light source, the intensity of the light in the individual segments of the full circle is plotted in this diagram. The lighting unit is this usually shown in a preferred position in the diagram. For example, the portion of the optical axis oriented in the emission direction of the light source is drawn in the zero-degree direction of the diagram. In the following, therefore, the zero-degree direction of the lighting unit is the direction emanating from the light source, which is oriented at least approximately parallel to the optical axis.

From the EP 1 255 132 A1 is a light unit with a light-emitting diode known. The light distribution body is placed on the light emitting diode, wherein the gap between the two bodies can be filled with transparent material. When passing through the different materials, a part of the light is absorbed. The light is deflected by 90 degrees. To use this light unit as a headlight, for example, a flat reflector with a large diameter is required.

The present invention is therefore based on the problem to develop a compact lighting unit with a high optical efficiency.

This problem is solved with the features of the main claim. For this purpose, the light distribution body is part of the light emitting diode. The section of the light distribution body resting against the non-glimmering light source has as an envelope an ellipse section at least in a sectional plane which comprises the optical axis. At least one major half-axis of this ellipse is offset in the zero-degree direction from the non-glowing light source. In addition, the radius of the semi-circle at the end of the semi-major axis is between 30% and 90% of the length of the semi-major axis.

Figur 1:

Leuchteinheit mit Leuchtdiode;

Figur 2:

Schnitt durch die Figur 1;

Figur 3:

Lichtverteilungsdiagramm der Leuchteinheit nach Figur 1;

Figur 4:

Leuchteinheit mit Leuchtdiode und Reflektor.

Further details of the invention will become apparent from the dependent claims and the following description of schematically illustrated embodiments.

FIG. 1:

Light unit with LED;

FIG. 2:

Section through the figure 1;

FIG. 3:

Light distribution diagram of the lighting unit of Figure 1;

FIG. 4:

Light unit with LED and reflector.

FIG. 1 shows a wire model of a light-emitting diode (20) as an example of a lighting unit (10). The light emitting diode (20) comprises a non-glare light source (21), e.g. a light emitting chip (21) and a light distribution body (31). The electrical connections of the light-emitting diode (20) are not shown here. FIG. 2 shows a section through this light-emitting diode (20), the sectional plane of this representation comprising the optical axis (5).

The optical axis (5) of the lighting unit (10), for example, is aligned normal to the light-emitting chip (21) and penetrates the light distribution body (31). The latter is arranged rotationally symmetrical to the optical axis (5) in this embodiment. It can also be square, rectangular, elliptical, etc. formed in the front view. In the light distribution diagram, the light source is arranged in the center, so that the zero-degree direction (2) originates at the light-emitting chip (21). It is oriented here parallel to the optical axis (5) in the direction of the end face (43) of the light distribution body (31), which faces away from the light-emitting chip (21). In the illustration of FIGS. 1-4, the zero-degree direction (2) points upwards.

In FIGS. 1 and 2, the light-emitting chip (21) is embedded in the lower region of the light distribution body (31), such that the light distribution body (31) bears against and surrounds the light-emitting chip (21).

The light distribution body (31) has along the optical axis (5) above the non-glimmering light source (21) e.g. a length of 3 millimeters. Its maximum diameter in a plane normal to the optical axis (5) is for example 5 millimeters. The length of the Lichtverteilkörpers (31) is thus less than 70% of its maximum diameter in this embodiment. The light distribution body (31) may have greater or smaller than the dimensions mentioned. Thus, the diameter of the light distribution body (31) may be e.g. between 3 millimeters and 8 millimeters.

The light distribution body (31) comprises two sections (32, 42) of at least approximately the same length which are arranged one behind the other in the zero-degree direction (2) and are interconnected by means of a transition region (61) formed as a constriction (62). The lower portion (32) shown in Figure 1 has at least approximately the shape of a semi-ellipsoid (33) whose center and section plane is normal to the optical axis (5). On the lower portion (32) sits as upper portion (42) e.g. a truncated cone (44) that widens in the zero-degree direction (2). The end face (43) of the Lichtverteilkörpers (31) has a central recess (49). The diameter of the constriction (62) in this embodiment is 45% of the maximum diameter of the Lichtverteilkörpers (31).

In the sectional view of Figure 2 of the semi-ellipsoid (33) is shown as a semi-ellipse (34). The horizontal central axis of the semi-ellipse (34) is formed in this embodiment by two aligned semi-major axes (36), of which only one shown in FIG is. These large semiaxes (36) lie, for example, parallel to the light-emitting chip (21) and are offset from the light-emitting chip (21) by, for example, 1% of the diameter of the light distribution body (31) in the zero-degree direction (2). The imaginary small semi-axis of the half ellipse (34) lies on the optical axis (5).

On the large semi-axes (36) lie the midpoints (38) of Schmiegkreise. These Schmiegkreise affect the half ellipse (34) at least in the end points (37) of the major semi-axes (36). The radius of the Schmiegkreise is for example between 40% and 90% of the length of the major half-axes (36) of the semi-ellipse (34). In the illustration of Figure 2, the radius is 60% of this length. Optionally, the half ellipse (34) may have the shape of an oval. The Schmiegkreis then affects the Halbellipse (34) along a quarter circle. The line delimiting the lower portion (32) may also comprise a portion of a semi-ellipse (34), for example a light distribution body (31) which is a segment of a body rotationally symmetrical to the optical axis (5).

The half ellipse (34) is e.g. tangentially in the example formed as a groove throat constriction (62). Their radius is e.g. 2% of the length of the semi-ellipse (34).

The maximum diameter of the truncated cone (44) is for example 90% of the maximum diameter of the Lichtverteilkörpers (31). Its lateral surface (46) has an upper (47) and a lower portion (48). In the upper region (47), the lateral surface (46) is inclined here by 20 degrees to the optical axis (5). The length of this region (47), measured parallel to the optical axis (5), is for example 35% of the length of the Lichtverteilkörpers (31). In the lower area (48) is in this Embodiment, the inclination of the lateral surface (46) to the optical axis (5) 60 degrees. The lateral surface (46) can also be constructed in steps. The steps then include, for example, a plurality of surfaces offset from one another and inclined at 20 degrees to the optical axis.

The depression (49) of the light-emitting chip (21) facing away from the end face (43) is funnel-shaped and tapers in the direction of the light-emitting chip (21). She runs to a peak (52). Its depth is for example 48% of the length of Lichtverteilkörpers (31). The largest diameter of the recess (49) in this embodiment is 80% of the maximum diameter of Lichtverteilkörpers (31). The generatrix of the boundary surface (51) of the recess (49) is a parabola in this embodiment, cf. Figure 2. The focal point of the parabola is here in the e.g. as a punctiform light emitting chip (21). Instead of a parabola, the generatrix of the depression (49) can also be another continuous or sectionally continuous geometric curve.

The production of the light emitting diode (20) takes place, for example by injection molding in two steps. The material used in the injection molding process in both steps is, for example, a highly transparent thermoplastic, for example modified polymethyl methacrylimide (PMMI), polysulfone (PSU), silicone, etc. In the first step, the light-emitting chip (21) is surrounded by an electronic protective device, not shown here. In the second step, this is then overmolded to form the Lichtverteilkörpers (31). This results in a homogeneous Lichtverteilkörper (31), which rests directly on the light-emitting chip (21). However, the light-emitting diode (20) can also be produced in a single work step. Optionally, the shape the surface of Lichtverteilkörpers (31) are additionally changed by means of a forming process.

During operation of the light emitting diode (20), the light emitting chip (21), which is assumed to be punctiform, emits light as a Lambertian radiator at least approximately into a half space. FIG. 2 shows, by way of example, individual light beams (82-86) offset by 15 degrees from one another. Light (82-84) which is at an angle between e.g. 85 degrees and 35 degrees to the optical axis (5) is emitted hits the interface (35) of the semi-ellipsoid (33). The angle of 85 degrees here is the angle of the imaginary ray of light that passes through the center (38) of Schmiegkreises. Upon impact with the interface (35), the light (82-84) with the normal at the point of impact includes an angle smaller than the critical angle of total reflection. This critical angle is here, for example, 43 degrees. The light (82-84) passes through the interface (35). In the transition from the optically denser material of the Lichtverteilkörpers (31) in the optically thinner environment (1), e.g. Air, the light (82-84) is broken away from the solder. In the embodiment shown here, the refractive index is 1.635. The light emitted from the light-emitting chip (21) in the aforementioned angular segment now exits in an angular segment of, for example, 62 degrees to 85 degrees to the optical axis (5) into the environment (1). The boundary surface (35) of the semi-ellipsoid (33) thus acts as a converging lens for the light emitted by the light-emitting chip (21). In a polarized light distribution diagram, cf. FIG. 3, a high light intensity results in this segment.

The interface (35) of the hemi-ellipsoid (33) may be designed in the manner of a Fresnel lens. Thus, it may comprise individual, designed as Fresnel elements circumferential rings. The Theoretical envelope of such a Fresnel lens is the above-described condenser lens.

Light (85, 86) emitted from the light-emitting chip (21) at an angle to the optical axis (5) smaller than 35 degrees reaches the boundary surface (51) of the recess (49). The light (85, 86) impinges on this boundary surface (51) at an angle to the normal at the point of impact that is greater than the critical angle of total reflection. The boundary surface (51) forms for the incident light (85, 86) a total reflection surface (91) at which the incident light (85, 86) in the direction of the lateral surface (46) is reflected. A small portion of the light emitted by the light-emitting chip (21) passes through the tip (52) of the depression (49) into the environment (1).

The total reflection surface (91) may for example be composed of individual surface elements. The connecting line of the surface element to the light-emitting chip (21) then encloses with the normal in this surface element an angle which is greater than the critical angle of total reflection. The boundary surface (51) of the recess (49) may also be mirrored. It can be larger than the total reflection area (91).

The light (85, 86) reflected at the total reflection surface (91) is at least approximately parallel to one another in this exemplary embodiment. It impinges on the lateral surface (46) at an angle to the normal at the point of impact which is smaller than the critical angle of total reflection. When passing through the lateral surface (46), which forms a refraction surface (93), it is refracted away from the solder. In the exemplary embodiment shown here, the light (85, 86) enters at an angle of 75 degrees to the optical axis (5) Environment (1). The lateral surface (46) can also be arranged such that the reflected light (85, 86) penetrates it without refraction.

The light (85, 86) emerging from the upper section (42) overlaps with the light (82-84) emerging from the lower section (32) of the light distribution body (31). The light emitted by the light-emitting chip (21) is deflected. The maximum of the light intensity is for example in a range of 75 degrees to the optical axis (5). Due to the homogeneous material of the Lichtverteilkörpers (31) and the low refractive losses, the lighting unit described here (10) has a high efficiency.

The transition region (61) between the lower section (32) and the upper section (42) of the light distribution body (31) is defined, for example, such that a light beam tangent to the transition region (61) in the representation of FIG. 2 at the upper end of the boundary surface (FIG. 51). The imaginary circumferential line at the upper end of the boundary surface (51) is determined, inter alia, by the refractive index and the desired light exit angle of the lower section (32). For example, in a horizontal transition between the lower portion (32) and the transition region (61) and a desired light exit angle alpha of the limiting light beam from the lower portion (32) to a horizontal plane, the limit angle (alpha + x) of the perimeter of the perimeter surface (51) to a horizontal plane: $$\begin{array}{l}\sin \left(\mathrm{x}\right)\mathrm{/}\left(\mathrm{n}\mathrm{-}\cos \left(\mathrm{x}\right)\right)\mathrm{=}\tan \left(\mathrm{90}\mathrm{°}\mathrm{-}\mathrm{alpha}\right)\mathrm{-}\tan \left(\mathrm{x}\right)\mathrm{/}\mathrm{(}\mathrm{1}\mathrm{+}\mathrm{(}\tan \mathrm{(}\mathrm{90}\mathrm{°}\mathrm{-}\\ \mathrm{alpha}\mathrm{)}\mathrm{*}\tan \left(\mathrm{x}\right)\mathrm{)}\end{array}$$

In this formula, n is the refractive index of the material of the lower portion (32). The origin of the angle alpha is the point of passage of the light beam through the interface (35) of the lower portion (32). The origin of the critical angle (alpha + x) is the light-emitting chip (21). The limit angle of the boundary surface (51) thus determined also determines the lateral surface (46) of the upper section (42).

FIG. 3 shows the polar light distribution diagram for the lighting unit (10) shown in FIGS. 1 and 2. As Radiant (102) the radiation angles are shown, wherein the upward pointing direction is the zero-degree direction (2). On the Radianten (102) concentric circles (103) are arranged. These show from the center (101) outwardly decreasing luminous intensity values, e.g. in candelas per kilo. In this polar light distribution diagram, the light emerging from the light distribution body (31) thus has a maximum intensity in a region around 75 degrees on both sides of the zero-degree direction (2). The intensity decreases both at smaller angles and at larger angles.

In order to construct a lighting unit (10) whose intensity maximum lies in a segment which is smaller than 75 degrees, for example, the center plane of the half-ellisoid (33) is shifted away from the light-emitting chip (21) in the zero-degree direction (2). At the same time, for example, the angle of inclination of at least the upper region (47) of the lateral surface (46) to the optical axis (5) can be increased.

If the intensity maximum is, for example, at an angle of 85 degrees to the optical axis (5), the median plane of the semiellipsoid (33) can be arranged closer to the light-emitting chip (21) become. At the same time, the inclination angle, for example, of the upper region (47) of the lateral surface (46) to the optical axis (5) can be reduced.

In order to produce a lighting unit (10) with a narrow radiation segment, for example, the distance of the center points (38) of the Schmiegkreise to the light-emitting chip (21) can be made large. Conversely, for a broad emission segment, the centers (38) of the flywheel circuits can be placed close to the light-emitting chip (21). To set the desired light distribution diagram, a variation of the osculating circle radii and thus of the curvature of the ellipsoid (33) is also conceivable.

4 shows a lighting unit (10) with a light-emitting diode (20) and a light-emitting diode (20) optically downstream reflector (70) is shown.

The light-emitting diode (20) largely corresponds to the light-emitting diode (20) shown in FIGS. 1 and 2. In the embodiment shown here, however, the refractive index of the material of the Lichtverteilkörpers (31), for example, 1.4. The light (81-87) emerging from the light-emitting diode (20) passes over a segment of 50 degrees to 90 degrees to the optical axis (5).

The reflector (70) is concave and constructed, for example, coaxially to the optical axis (5). In its center sits the LED (20). It comprises here two reflection areas (71, 72). An inner cone-shaped region (71) is surrounded by an outer, eg parabolic, region (72). The conical region (71) is inclined here, for example, by 45 degrees to the optical axis (5).

In the sectional view of Figure 4, the light beam (81) is shown, which passes through the center (38) of the semi-circle of the semi-ellipse (34). This light beam (81) strikes normal on the interface (35) and is not broken when passing through the interface (35). The inclination of the light beam (81) exiting into the environment (1) to the optical axis (5) is for example 85 degrees.

In this figure 4, the light beam (87) is further shown, which affects the constriction (62). This light beam (87) is the light beam (87) with the greatest inclination angle with respect to the optical axis (5), which impinges on the total reflection surface (91). It is reflected at the light emitting chip (21) remote end (92) of the total reflection surface (91) in the direction of the lateral surface (46) and penetrates, for example, without refraction, the lateral surface (46). The inclination of the light beam (87) exiting into the environment (1) to the optical axis (5) is for example 90 degrees.

The two described light beams (81, 87) intersect in the sectional representation of FIG. 4 at a point (89) which lies, for example, on the reflector (70). At this point (89), the conical region (71) merges into the parabolic region (72). In three-dimensional space, this point (89) is a point of a line which, for example, has a constant distance from the light distribution body (31). In the case of a light-emitting diode (20) with a rotationally symmetrical light distribution body (31), this line is a circle whose center lies, for example, on the optical axis (5). The transition of the two reflector regions (71, 72) may have a greater distance from the light-emitting diode (20) than the line (89).

Light (85, 86) emitted from the light-emitting chip (21) at an angle to the optical axis (5) smaller than the inclination angle of the light beam (87) impinges on the cone-shaped portion of the reflector (70). There, the light (85, 86) is reflected in the zero-degree direction (2). The individual light beams (85, 86) are now, for example, parallel to one another.

The light (82-84) emitted from the light-emitting chip (21) in an angular segment bounded by the angles of inclination of the emitted light beams (81) and (87) strikes the parabolic region (72) of the reflector (70 ). Here it is reflected in the zero-degree direction (2).

Seen from a distance, this results in a largely homogeneous luminous lighting unit (10) without dark spots.

The reflector (70) can also be designed with a single conical or a single arched area. Hereby, for example, a diffused portion of the light emitted by the lighting unit (10) can be generated in a targeted manner. It is also conceivable to form the reflector (70) parabolically in the basic form. Pillow-like elevations and / or depressions are then arranged on the reflector surface, for example.

The entire light emerging from the light-emitting diode (20) is distributed on a large surface of the reflector (70) and reflected there. Minor inaccuracies of the coating of the reflector (70) do not affect the light emitted by the lighting unit (10). The inserted reflector (70) can thus be manufactured in a diameter range, in which, for example, the coating can be produced safely and accurately.

The lighting unit (10) is thus compact and highly efficient.

The lighting unit (10) can also be designed such that in a view from the end face (43) of the reflector (70) and / or the Lichtverteilkörper (31) is a segment of a rotationally symmetrical body. A square, rectangular, etc. limited by a polygon, etc. shape of the Lichtverteilkörpers (31) and / or the reflector (70) is conceivable. The light emitting diode (20) may also comprise a plurality of light emitting chips (21).

Combinations of the various embodiments are conceivable.

LIST OF REFERENCE NUMBERS

1

Surroundings

2

Zero-degree direction

5

optical axis

10

light unit

20

led

21

non-glimmering light source, light-emitting chip

31

light distribution

32

lower section of (31)

33

hemiellipsoid

34

hemiellipse

35

Interface of (33)

36

large half-axis of (34)

37

Endpoint of (36)

38

Center points of Schmiegkreise

42

upper section of (31)

43

front

44

truncated cone

46

Lateral surface of (44)

47

upper part of (46)

48

lower range of (46)

49

depression

51

Bounding area of (49)

52

Tip of (49)

61

Transition area

62

constriction

70

reflector

71

Reflection area, cone-shaped area

72

Reflection area, parabolic part

81

Light beam through (38)

82 - 86

light rays

87

Light beam tangential to (62)

89

Intersection of (81, 87), intersection line

91

Total reflection surface

92

End of (91), away from (21)

93

refraction surface

101

center

102

radians

103

Lines, circles

Claims (12)

Light-emitting unit (10) having a light-emitting diode (20) comprising at least one non-glimmering light source (21) and a light distribution body (31) optically connected to a non-glimmering light source (21), the light distribution body (31) being at least two in at least approximately parallel to the optical axis (5) the light unit (10) oriented zero-degree direction (2) has successively arranged sections (32, 42), wherein the non-glimmering light source (21) facing away from the end face (43) of the Lichtverteilkörpers (31) has a recess (49) and wherein each boundary surface (51) of the depression (49) comprises a total reflection surface (91) for the light (81-87) emitted by the non-glimmering light source (21), characterized - That the light distribution body (31) is part of the light emitting diode (20), in that the section (32) of the light distribution body (31) resting against the non-glimmering light source (21) has an ellipse section as envelope, at least in a sectional plane which comprises the optical axis (5), - That at least one large half-axes (36) of this ellipse in the zero-degree direction (2) offset from the non-glimmering light source (21) is arranged, and - That the radius of Schmiegkreises at the end point (37) of the major half-axis (36) between 30% and 90% of the length of the major half-axis (36). Lighting unit according to claim 1, characterized in that the light distribution body (31) is rotationally symmetrical to the optical axis (5) of the lighting unit (10). Lighting unit according to claim 1, characterized in that the portion (42) has at least approximately a frusto-conical shape, wherein the cone widens in the zero-degree direction (2). Lighting unit according to claim 1, characterized in that the median plane of the half ellipsoid (33) is offset by at least 1% of the diameter of the light emitting diode (20) to the non-glimmering light source (21). Lighting unit according to claim 1, characterized in that the length of the Lichtverteilkörpers (31) of the light emitting diode (20) above the nichtglimmenden light source (21) is at most 70% of its diameter. Lighting unit according to claim 1, characterized in that the diameter of the Lichtverteilkörpers (31) is smaller than 8 millimeters. Lighting unit according to claim 1, characterized in that the total reflection surface (91) at least one refraction surface (93) is optically connected downstream. Lighting unit according to claim 1, characterized in that the light-emitting diode (20) is a reflector (70) optically connected downstream. Lighting unit according to claim 8, characterized in that the reflector (70) comprises a conical region (71) and a parabolic region (72). Lighting unit according to claim 8, characterized in that the light beams (81) on which lie the centers (38) of the Schmiegkreise and the light beams (87) at the said light emitting chip (21) remote end (92) of the total reflection surface (91 ), intersect in at least one line (89). Lighting unit according to claims 2 and 10, characterized in that the line (89) is a circle, wherein the center of the circle lies on the optical axis (5). Lighting unit according to claims 9 and 11, characterized in that the transition between the conical (71) and the parabolic part (72) of the reflector (70) is at least approximately on this circle.

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