EP1903275B1 - Illumination unit with light diode, light conduction body and secondary lens - Google Patents

Description

The invention relates to a lighting unit having at least one light emitting diode, which comprises at least one light emitting chip as a light source, with at least one of the light emitting diode optically downstream, in the Lichtausbreitungsrichtung expanding light guide body and a light guide body optically downstream secondary lens, wherein two oppositely arranged, the light guide delimiting surfaces which form a bottom surface and a top surface in a longitudinal section intersecting these surfaces, have oppositely curved curve sections adjoining the light entry surface of the light guide body, the bottom surface having a curve section positively curved with respect to the light propagation direction and the cover surface having a negative direction with respect to the light propagation direction curved curved portion and such a light guide.

From the DE 10 2005 017 528 A1 is such a light unit known. This light unit requires a large secondary lens to absorb the light divergently emerging from the light guide light. The light unit thus requires a large amount of space.

See also EP 1630576 as the closest prior art.

The present invention is therefore based on the problem to develop a lighting unit with a high light output, which takes up a small space.

This problem is solved with the features of the main claim. In said longitudinal section, at least one of the curves delimiting the light guide body has a point of inflection.

Figur 1:

Dimetrische Ansicht einer Leuchteinheit;

Figur 2:

Ansicht von unten auf Figur 1;

Figur 3:

Anordnung der Lichtquellen;

Figur 4:

Ansicht des Lichtleitkörpers von der Lichteintrittsseite;

Figur 5:

Dimetrische Ansicht des Lichtleitkörpers;

Figur 6:

Dimetrische Ansicht des Lichtleitkörpers von unten;

Figur 7:

Lichtaustrittsfläche;

Figur 8:

Längsschnitt einer Leuchteinheit;

Figur 9:

Ansicht eines Lichtleitkörpers schräg von oben;

Figur 10:

Strahlengang der Leuchteinheit;

Figur 11:

Strahlengang im Lichtleitkörper;

Figur 12:

Lichtverteilungsdiagramm;

Figur 13:

Lichtaustrittsfläche mit versetztem Übergangsbereich;

Figur 14:

Lichtaustrittsfläche mit gekrümmten Unterkanten;

Figur 15:

Lichtverteilkörper mit gewölbten Übergangsbereich von unten.

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

FIG. 1:

Dimetric view of a light unit;

FIG. 2:

View from below FIG. 1 ;

FIG. 3:

Arrangement of the light sources;

FIG. 4:

View of the light guide from the light entrance side;

FIG. 5:

Dimetric view of the light guide body;

FIG. 6:

Dimetric view of the light guide body from below;

FIG. 7:

Light-emitting surface;

FIG. 8:

Longitudinal section of a lighting unit;

FIG. 9:

View of a light guide obliquely from above;

FIG. 10:

Beam path of the lighting unit;

FIG. 11:

Beam path in the light guide body;

FIG. 12:

Light distribution diagram;

FIG. 13:

Light exit surface with offset transition region;

FIG. 14:

Light exit surface with curved lower edges;

FIG. 15:

Light distribution body with arched transition area from below.

The Figures 1 and 2 show a lighting unit (10), for example, a light module (10) of a motor vehicle headlight, in a dimetric view and in a view from below. The light module (10) comprises, for example, a light-emitting diode (20), a primary optic (30) and a secondary optic (90). The light propagation direction (15) is oriented by the light-emitting diode (20) in the direction of the secondary optics (90). The optical axis (11) of the light module (10) here intersects the geometric center of the light-emitting diode (20) and penetrates the primary (30) and the secondary optics (90).

The light-emitting diode (20), for example a light-emitting diode (20), is seated, for example, in a base (26) and in this exemplary embodiment comprises a group (21) of four light-emitting chips (22-25) which are arranged in a square, cf. FIG. 3 , Each of the light sources (22-25) thus has two immediately adjacent light-emitting chips (23, 24, 22, 25, 22, 25, 23, 24). The light-emitting chips (22-25) of the group (21) can also be arranged in a rectangle, in a triangle, in a hexagon, in a circle with or without a central light source, etc. The individual light-emitting chip (22-25) is square in this embodiment and has, for example, an edge length of one millimeter. The distance of the light-emitting chips (22-25) from one another is, for example, one tenth of a millimeter. An embodiment with a single light-emitting chip (22, 23, 24, 25) is also conceivable. The light-emitting diode (20) here has a transparent body, which in the light propagation direction (15) from the base (26) has a length of, for example, 1.6 millimeters.

The primary optic (30) comprises in the in the Figures 1 and 2 illustrated embodiment, a light guide body (31) and the light guide body (31) in the light propagation direction (15) downstream optical lens (81). The distance of the light guide body (31) to the light emitting diode (20) is for example a few tenths of a millimeter, for example between 0.2 millimeters and 0.5 millimeters. The intermediate space (16) between the light guide body (31) and the light-emitting diode (20) can be filled, for example, with a silicone-like, transparent material.

The light guide body (31) is a plastic body made of a highly transparent thermoplastic material, e.g. Polymethacrylic acid methyl ester (PMMA) or polycarbonate (PC). This material of the light guide body (31) formed, for example, as a solid body has e.g. a refractive index of 1.49. The length of the light guide body (31) is 13.5 millimeters in this embodiment. The light guide body (31) of the light unit (10) described here may be e.g. also have a length between 15 and 16 millimeters.

In the FIGS. 4 to 7 the light guide body (31) is shown in detail. This shows the FIG. 4 a view of the light guide body (31) from the light entry side (32). In the FIGS. 5 and 6 are shown dimetric views of the light guide body (31) and the FIG. 7 shows the light exit surface (34). The light entry surface (32) facing the light sources (22-25) and the light exit surface (34) facing away from the light sources (22-25) are arranged parallel to one another and normal to the optical axis (11) in this exemplary embodiment. The light entry surface (32) is here a trapezoidal, flat surface. The short baseline, for example, has a length of 2.4 millimeters, is located below. The overhead long baseline is for example 3.02 millimeters long. The surface area of the light entry surface (32) in this embodiment is 5.5 square millimeters. The light entry surface (32) can also be square, rectangular, etc.

The light exit surface (34), for example, has an area of 44 square millimeters. Its height is 5.8 millimeters, its maximum width is 9 millimeters. The light exit surface (34) has in the embodiment at least approximately the shape of a portion of an oval. The imaginary center line of the light exit surface (34) is, for example, offset downwards by 7% of the height of the light exit surface (34) with respect to the optical axis (11). The lower edge (35) of the light exit surface (34) has two mutually offset in height portions (36, 37) which are interconnected by means of a connecting portion (38).

The side surfaces (41, 43) of the light guide body (31) are arranged in mirror image to each other. They each comprise a flat surface section (42, 44). These surface portions (42, 44) lie in planes which are e.g. together include an angle of 13 degrees oriented in the direction of the light guide body (31). The imaginary line of intersection of the planes lies below the light guide body (31). The surface portions (42, 44) referred to herein as flat surface portions (42, 44) may also be e.g. be twisted in the longitudinal direction.

The in the FIGS. 4 and 5 Overlying top surface (51) of the light guide body (31) comprises in this embodiment, a cylindrically mounted parabolic surface portion (52), a uniaxially curved surface portion (53) and a flat surface portion (54). These surface sections (52-54) are arranged one behind the other in the light propagation direction (15), the parabolic surface section (52) being in contact with the light entry surface (32) adjacent and the planar surface portion (54) adjacent to the light exit surface (34). The imaginary axes of curvature of the surface sections (52, 53) lie, for example, parallel to the upper edge (33) of the light entry surface (32).

The length of the parabolic surface portion (52) is e.g. 30% of the length of the top surface (51). The focal line (55) of the associated parabolic surface in this embodiment is e.g. in the middle in the light entry surface (32). It is, for example, oriented parallel to the upper edge (33) of the light entry surface (32) and cuts e.g. the optical axis (11). The parabolic surface portion (52) is thus mathematically negative with respect to the light propagation direction (15), i. clockwise, curved.

In the FIGS. 8 and 11 the cover surface (51) is shown in longitudinal section as a curve (61) and the parabolic surface section (52) as a parabolic section (62). The parabolic section (62) is part of a second order curve. For example, it is rotated clockwise by 118 degrees with respect to a parabola that is symmetrical to the upward-oriented ordinate of a Cartesian coordinate system lying in the plane of the drawing. The imaginary pivot point of the parabola - and of the parabola-related coordinate system - is the focal point (65) as the point of the focal line (55). The abscissa of the parabolic coordinate system is the guideline of the parabola, the ordinate intersects the focal line (55). The distance of the focal point from the origin of the parabolic coordinate system in this embodiment is 1.49 millimeters. With y as the ordinate value and x as the abscissa value of the parabola-related coordinate system, the parabola shown here has at least approximately the equation: y = 0.15 * x ² + x

The length of the curved surface portion (53) is for example 45% of the length of the light guide body (31). The bending radius corresponds for example to two and a half times the length of the light guide body (31). The bending line lies outside the light guide body (31) on the side of the cover surface (51). The surface portion (53) is thus mathematically positive, counterclockwise, curved. The transition between the parabolic surface portion (52) and the curved surface portion (53) is tangential. The top surface (51) has a turning line (56) in this transition. In longitudinal section, cf. the FIGS. 8 and 11 , the curve (61) has a turning point (66).

The curved surface portion (53) merges into the flat surface portion (54). The latter, for example, encloses an angle of 12 degrees with a plane normal to the light entry surface (32) in which the upper edge (33) lies. In longitudinal section, the curve (61) here has a straight section (64).

The upper longitudinal edges of the in the FIGS. 4 and 5 illustrated light guide body (31) are rounded. The radius of curvature increases in the light propagation direction (15), for example linearly from zero millimeters to four millimeters. The rounding (57) can also be formed continuously in regions. They pass tangentially into the adjacent surfaces (41, 51, 43, 51). In the FIGS. 5 and 6 these transitions are shown as solid lines for clarity. A version without rounding (57) is conceivable.

The bottom surface (71) of the light guide body (31) in this embodiment comprises two staggered parabolic surface sections (72, 73) which are cylindrically mounted. The two parabolic surface portions (72, 73) are, for example, a common Axis, for example, the upper edge (33) of the light entry surface (32), rotated against each other. The twist angle is 2 degrees in this embodiment, for example, in the light propagation direction (15) left parabola surface portion (73) further protrudes from the light guide body (31) than the right parabolic surface portion (72). The two parabolic surface sections (72, 73) have, for example, a common focal line (74) which, for example, coincides with the upper edge (33) of the light entry surface (32). The outlet of both parabolic surface sections (72, 73) on the light exit surface (34) is parallel to the optical axis (11). At this time, the parabolic surface portion (72) abuts the lower edge portion (36) and the parabolic surface portion (73) abuts the lower edge portion (37).

In the in the FIGS. 8 and 11 The longitudinal section shown is, for example, the parabolic surface section (72) a parabola section (76). The associated parabola, for example, is rotated clockwise by 71.5 degrees with respect to a parabola that is symmetrical to the upward-oriented ordinate of a Cartesian coordinate system lying in the plane of the drawing. The imaginary pivot point of the parabola - and of the parabola-related coordinate system - is the focal point (78) as the point of the focal line (74). The abscissa of the parabolic coordinate system is the guideline of the parabola, the ordinate intersects the focal point (78). The distance of the focal point (78) from the origin of the parabolic coordinate system in this embodiment is 2.59 millimeters. With y as the ordinate value and x as the abscissa value of the parabola-related coordinate system, the parabola shown here has at least approximately the equation: y = 0.17 * x ² + 0.15 * x + 1.05.

Between the two parabolic surface sections (72, 73) lies in this embodiment, a transition region (75). This is arranged at least approximately centrally along the bottom surface (71). It closes with the adjacent parabola sections (72, 73) e.g. an angle of 135 degrees. The height of the transition region (75) thus increases in the light propagation direction (15). In this embodiment, the height of the transition region (75) at the transition region (38) of the light exit surface (34) is 0.5 millimeters.

The optical lens (81) of the primary optics (30) is, for example, a plano-convex aspheric condenser lens (81), for example a condenser lens. The plan side (82) of the lens (81) lies in the representation of Figures 1 and 2 at the light exit surface (34) of the light guide body (31). The optical lens (81) may also be integrated in the light guide body (31). The maximum diameter of the optical lens (81) is, for example, 30% greater than the length of the optical waveguide (31). The longitudinal section of the optical lens (81) is, for example, a segment of an ellipse whose major axis is two and a half times and whose minor axis is 160% of the length of the optical waveguide (31). The thickness of the optical lens (81) is here 50% of the length of the light guide body (31). Optionally, the light module (10) may be designed without the optical lens (81), cf. the FIGS. 8 and 10 ,

The secondary optics (90) in this embodiment comprises a secondary lens (91). This is, for example, an aspheric plano-convex lens. The envelope of this lens is eg a sphere section. The center (95) of the secondary lens (91) and the lower edge (35) of the light exit surface (34) of the light guide body (31) have, for example, at least approximately the same distance from the optical axis (11) of the light module (10). The radius of the ball section is in the presentation of the Figures 1 and 2 240% and the height 110% of the length of the light guide body (31). The maximum distance of the plane surface (92) from the light exit surface (93), the thickness of the secondary lens (91) corresponds for example to the length of the light guide body (31). The distance of the secondary lens (91) from the light exit surface (34) is for example 260% of the length of the light guide body (31).

In operation of the light module (10), light (100) is e.g. emitted from all the light sources (22-25) and passes through the light entry surface (32) into the light guide body (31). Each light-emitting chip (22-25) acts as a Lambertian emitter, which emits light (100) in the half-space.

In the FIG. 10 For example, a beam path of a light module (10) is shown in a longitudinal section of the light module (10). The light module (10) shown here corresponds to that in the FIG. 8 illustrated light module (10). The beam path within the light guide (31) shows the enlarged FIG. 11 ,

In the Figures 10 and 11 By way of example, light beams (101-109) are shown which are emitted by two light-emitting chips (23, 25) arranged one above the other. The light-emitting chips (23, 25) are shown here as punctiform light sources. From the upper light-emitting chip (23), for example, the light beams (101 - 105) are shown, which are emitted offset by 15 degrees to each other. Here, for example, the light beam (101) is emitted upward by 45 degrees, while the light beam (105) is emitted downward by 45 degrees with respect to the optical axis (11). The respective light beams of the lower light-emitting chip (25) are the light beams (106-109).

Light (103) emitted from the upper light emitting chip (23) parallel to the optical axis (11) penetrates the light exit surface (34) of the light guide body (31) in the normal direction. It impinges on the plane surface (92) of the secondary lens (91) also in the normal direction, penetrates the secondary lens (91) and is refracted on exiting the secondary lens (91), for example, from the solder in the passage point.

The light beams (102) emitted from the upper light-emitting chip (23) and enclosing an upward angle of 15 degrees and 30 degrees with the optical axis (11) impinge on an upper boundary surface (151) of the light guide body (31). This upper interface (151) is formed by the top surface (51) and has a maximum size. The respective impact point lies here in the area of the parabolic surface (52). The incident light beams (102) include with the normal at the point of impact an angle which is greater than the critical angle of total reflection for the transition of the material of the light guide body (31) with air. The upper interface (151) thus forms a total reflection surface (151) for the incident light (102). The reflected light beams (102) pass through the light exit surface (34), being refracted away from the solder in the passage point. Upon entry into the secondary lens (91), the light beams (102) lying approximately parallel here are refracted in the direction of the solder in the respective passage point and are broken away from the solder when they exit into the environment (1). The illustrated light beams (102) occur here in the lower segment of the secondary lens (91) in the environment (1).

The light (101) emitted from the upper light-emitting chip (23) at an upward angle of 45 degrees is first detected at the upper total reflection surface (151). reflected. The reflected light (101) strikes the lower boundary surface (161). The angle of incidence of the light (101) and the normal at the point of impact include an angle greater than the critical angle of total reflection. The lower boundary surface (161) thus acts for the incident light (101) as the lower total reflection surface (161). The light (101) reflected by this total reflection surface (161) penetrates the light exit surface (34) and the secondary lens (91), being refracted as it passes through the respective body boundary surfaces (34, 92, 93). This light (101) enters the environment (1) in the upper segment of the secondary lens (91).

The in the Figures 10 and 11 The light beam (104) of the upper light-emitting chip (23), which has a downward angle of 15 degrees with the optical axis (11), is not reflected in the light guide body (31). It is broken when passing through the light exit surface (34) and through the secondary lens (91). This light beam (104) lies in the lower segment of the secondary lens (91).

That in the mentioned Figures 10 and 11 light (105) emitted at a downward angle of 30 degrees and at 45 degrees to the optical axis (11) is totally reflected at the lower boundary surface (161) and passes through the light exit surface (34) and the secondary lens (91) with refraction in the environment (1). This light (105) lies in the upper segment of the secondary lens (91).

The light (108) emitted by the lower light-emitting chip (25) parallel to the optical axis (11) is at least approximately parallel to the light (103) of the upper light-emitting chip (23).

Light (107) emitted at an upward angle of 15 degrees strikes the upper boundary surface (151) in the region of the inflection line (56). Here it is completely reflected and passes under refraction through the light exit surface (34) and the lower segment of the secondary lens (91) through into the environment (1).

The in the Figures 10 and 11 Below 30 degrees and below 45 degrees to the optical axis (11), light rays (106) emitted from the lower light-emitting chip (25) are reflected at the upper (151) and lower (161) interfaces.

The light rays (109) of the lower light-emitting chip (25) including a downward angle of 15, 30 and 45 degrees with the optical axis (11) are reflected at the lower boundary surface (161). Under refraction they penetrate the light exit surface (34) and the secondary lens (91). For example, the light beams (109) emerging into the environment (1) are approximately symmetrical with respect to the optical axis (11).

Of the total light (100) emitted by the light sources (22-25), 48% is reflected at the lower boundary surface (161) and 26% of the light is reflected at the upper boundary surface (151) in this embodiment.

In the view from below, cf. FIG. 2 For example, the light beam (100) is widened to an angle of 17 degrees.

The illumination intensity distribution (170) generated by the light module (10), for example on a wall 25 meters away, is in the FIG. 12 shown. The midline (95) of the secondary lens (91) penetrates the measuring wall, for example, at the intersection (171) of two reference grid lines (172, 173). In this illustration, the horizontal grid lines (172) have a distance of two meters to each other on the measuring wall. The distances of the vertical grid lines (173) to each other here is for example five meters. The individual isolines (174) are lines of equal illuminance. Illuminance, measured in lux or lumens per square meter, increases from outside to inside in this diagram. An inner isoline (174) has, for example, 1.8 times the illuminance of a further outlying isoline.

On the measuring wall, the secondary lens (91) forms the light exit surface (34) or (83) of the primary optics (30). This light exit surface (34, 83) may be the light exit surface (34) of the light guide body (31) or the convex surface (83) of the condenser lens (81). The area (175) of the highest illuminance, the so-called hot spot (175), lies here on the right below the point of intersection (171). At the top, the illuminance decreases rapidly at the cut-off (176). The light-dark boundary (176) is here z-shaped. It has a higher section (177) on the right and a lower section (178) on the left. Both sections (177, 178) are interconnected by means of a connecting section (179) which, with the two other sections (177, 178), each have an angle of e.g. Includes 135 degrees. In this light-dark boundary (176), the lower edge (35) of the light exit surface (34) of the primary optics (30) is imaged.

The in the FIG. 12 illustrated illuminance distribution shows a wide illuminated area (181) whose illuminance in width with the distance from the intersection (171) decreases. Towards the bottom, the illuminated area (181) has a height of, for example, four to six meters.

When operating e.g. a plurality of light modules (10) results in a blurred limited, streak and spot-free illuminated area (181) with a sharp, z-shaped cut-off (176).

The light module (10) shown in the embodiments has a high light output due to its geometric design and requires only a small space. The relative coupling-out efficiency achievable with such a light module (10) without additional antireflection coatings is 97% of the maximum possible coupling-out efficiency. This corresponds to an absolute value of 80% to 82%.

In order to change the altitude of the light distribution, the lower parabolic surface portions (72, 73) can be rotated about the focal line (74). So does in the view after FIG. 8 a rotation of the parabolic surfaces (72, 73) in a clockwise direction an increase in the light distribution. At the same time - if the optical axis (11) is not adjusted - the light-dark boundary (176) can be moved upwards. The intensity of the hot spot (175) is retained.

The light distribution at the measuring wall results from the superposition of different light components, cf. FIG. 10 , For example, the hot spot (175) is generated by the superimposition of light components which are delimited from the upper light-emitting chip (23) in a segment between, for example, 0 degrees and, for example, 15 degrees downwards and upwards with light components emitted from the lower light-emitting chip (FIG. 25) is limited between, for example, 0 degrees and eg 15 degrees upwards and between, for example, 30 degrees and eg 45 downwards.

To change the intensity of the hot spot (175), e.g. the overhead parabolic surface portion (52) are changed. Thus, for example-viewed in the longitudinal section of the light guide body 31-a rotation of the parabolic surface section 52 in a clockwise direction can mean a weakening of the intensity. A change of the outlet (54) of the top surface (51) alters the gradient of the light intensity distribution.

In addition, by moving the beginning of the connection area, you can specifically control the level of illuminance in the hot spot (175) and around the hot spot (175). An unfavorable choice can cause a weakening of the hot spot (175).

By means of the condenser lens (81), the light (100) emerging from the light exit surface (34) can additionally be bundled. Thus, a secondary lens (91) of small diameter can be used. The convex surface (83) of the condenser lens (81) is, for example, an aspherical surface.

The distance of the secondary (90) from the primary optics (30) also influences the illumination intensity distribution. In order to concentrate the light (100) diverging exiting from the primary optics (30) at a large distance, a larger secondary lens (91) is required than at a small distance. The larger secondary lens (91) allows - with identical light guide body (31) - the formation of the hot spot (175), while forming a basic light distribution, a small distance between primary (30) and secondary optics (90) and a small secondary lens (91) is required.

By means of the lateral surfaces (41, 43) and the rounded portions (57), the light distribution on the sides of the illuminated region (181) can be influenced. A rotation of the side surfaces (41, 43) - with the lower edge (35) fixed to one another - reduces the width of the light distribution diagram (171), cf. FIG. 12 , A reduction in the radii of the rounding (57) causes a sharper transition from the illuminated to the non-illuminated area in the corners.

In the FIG. 13 a light exit surface (34) of a light guide body (31) is shown. The main dimensions of this light exit surface (34) correspond to the main dimensions in the FIG. 7 illustrated light exit surface (34). The transition region (75) between the parabolic surfaces (72, 73) is compared to FIG. 7 moved to the left. When mounting a plurality of light modules (10) they are arranged so that during operation, the connecting portions (179) coincide. Thus, two asymmetrically split lighting profiles overlap only partially. In the middle, in the area of the desired hotspot (175) and on the z-shaped light-dark border (176), a region of high illuminance is achieved in comparison with the lateral areas.

The two parabolic surfaces (72, 73) can, as in the FIG. 14 shown to be inclined to each other. This can be used, for example, to compensate for distorted images in the target plane. The parabolic surfaces (72, 73) may also be curved in the transverse direction. Optionally, they may be additionally modified, for example, in the third of the light guide body (31) adjoining the light exit surface (34).

The connecting section (75) can be curved along the light distribution body (31), cf. FIG. 15 , The sharpness of the cut-off (176) is not affected. Indeed this can be used to influence the light concentration near the hot spot (175). For example, an arrangement of the optical waveguide (31) which is tilted laterally causes a shift of the center of gravity of the illuminance distribution (181) on the wall. In this embodiment, the light entrance (32) and the light exit surface (34) are not parallel to each other.

The connecting section (75) can have transition radii (77) in the transition to the parabolic surfaces (72, 73), cf. FIG. 6 ,

The light guiding body (31) may also comprise two underlying parabolic surfaces (72, 73) immediately adjacent to each other, e.g. inclined by 15 degrees to each other. Hereby, for example, an illumination can be generated with a 15 degree rise.

It is also conceivable to design the bottom surface (71) with only one continuous parabolic surface (72, 73), cf. FIG. 9 , With such a light module (10), for example, a horizontal light-dark boundary (176) is generated. The corresponding light module (10) can in this case be designed so that a hot spot (175) is generated. Also in this embodiment, the top surface (51) has a parabolic surface portion (52), a curved surface portion (53) and a flat surface portion (54). Between the parabolic surface portion (52) and the curved surface portion (54) is a turning line (56).

The bottom surface (71) can be described at least in regions by a family of adjacent parabolas oriented in the light propagation direction (15). These parabolas can have different parameters.

The bottom surface (71) and the top surface (51) of the light guide body (31) can also be reversed, so that the area designated here as the bottom surface (71) is at the top. The illumination intensity distribution is then designed such that the light-dark boundary (176) lies below.

The surfaces described here may be enveloping surfaces. Thus, the individual surface sections may be e.g. Be free-form surfaces whose envelope surface, e.g. Are parabolic surface. The focal lines (55, 74) may be e.g. be shifted in the light propagation direction (15).

It is also conceivable, for example, to execute the parabolic surface section (52) of the cover surface (51) with individual steps. From each two adjacent interface portions of the light guide (31) then comprises a boundary surface portion, for example, a parabolic surface-like total reflection surface (151) for the light emitted from the upper light-emitting chip (23) light (101 - 105), while the other interface portion of a total reflection surface for that of the lower light-emitting Chip (25) emitted light (106 - 109) comprises. Optionally, the bottom surface (71) can be made stepped.

LIST OF REFERENCE NUMBERS

1

Surroundings

10

Light unit, light module

11

optical axis

15

Light propagation direction

16

gap

20

Light emitting diode, light emitting diode

21

Group of light sources

22 - 25

Light sources, light emitting chips

26

base

30

primary optics

31

fiber-optic element

32

Light entry surface

33

upper edge of (32)

34

Light-emitting surface

35

Lower edge of (34)

36, 37

Sections of (35)

38

Transitional section of (35)

41

side surface

42

plane surface section

43

side surface

44

plane surface section

51

cover surface

52

Parabolic surface section

53

curved surface section

54

flat surface section; Spout of (51)

55

focal line

56

turning line

57

roundings

61

Curve

62

Curve section, parabolic section

64

straight section

65

Focal point of (62)

66

turning point

71

floor area

72

Parabolic surface section

73

Parabolic surface section

74

focal line

75

Transition area

76

Curve section, parabolic section

77

Transition radius

78

Focal point of (76)

81

optical lens, condenser lens, condenser lens

82

plan page

83

convex surface, light-emitting surface of (81)

90

secondary optics

91

secondary lens

92

plane surface

93

Light-emitting surface

95

Centerline of (91)

100

Light, light bundles

101-105

Beams of (23)

106-109

Beams of (25)

151

upper interface, total reflection surface

161

lower interface, total reflection surface

170

Illuminance distribution

171

intersection

172

Reference grid lines, horizontal

173

Reference grid lines, vertical

174

contours

175

Highest luminance area, hot spot

176

Light-off

177

Section of (176)

178

Section of (176)

179

connecting portion

181

illuminated area

Claims (17)

1. Lighting unit (10) having at least one light-emitting diode (20) comprising at least one light-emitting chip (22; 23; 24; 25) as the light source, having at least one light guide body (31) optically downstream of the light-emitting diode (20) and flaring out in the light propagation direction (15) and having a secondary lens (91) optically downstream of the light guide body (31), where two surfaces (51, 71) arranged opposite one another and limiting the light guide body (31), which in a longitudinal section bisecting these surfaces (51, 71) form a bottom surface (71) and a top surface (51), have opposingly curved sections (62, 76) adjoining the light entry surface (32) of the light guide body (31), where the bottom surface (71) comprises a curved section (76) positively curved relative to the light propagation direction (15) and the top surface (51) a curved section (62) negatively curved relative to the light propagation direction (15), characterized in that,

   - in the said longitudinal section at least one of the curves (62, 76) limiting the light guide body (31) has a reversal point (66).
2. Lighting unit (10) according to Claim 1, characterized in that the light-emitting diode (20) comprises a group (21) of light-emitting chips (22 - 25) as light sources.
3. Lighting unit (10) according to Claim 2, characterized in that each light-emitting chip (22 - 25) inside the group (21) has at least two directly adjacent light-emitting chips (23, 24; 22, 25; 22, 25; 23, 24).
4. Lighting unit (10) according to Claim 1, characterized in that the curved sections (62, 76) are parabolic sections.
5. Lighting unit (10) according to Claim 4, characterized in that the abscissas of the coordinate systems relative to the parabolas form with the optical axis (11) of the lighting unit (10) an angle of at least 50 degrees.
6. Lighting unit (10) according to Claim 4, characterized in that the surfaces (51, 71) have in each longitudinal section at least one parabolically curved section (62, 76).
7. Lighting unit (10) according to Claim 1, characterized in that the curve (61) containing the reversal point (66) comprises a straight section (64).
8. Lighting unit (10) according to Claim 1, characterized in that the light-emitting chips (22 - 25) are arranged in a square.
9. Lighting unit (10) according to Claim 1, characterized in that two surfaces (41, 43) of the light guide body (31) arranged opposite to one another and connnecting the top surface (51) and the bottom surface (71) each comprise at least one flat surface section (42, 44), where the associated planes form an acute angle outside the bottom surface (71) and oriented in the direction of the light guide body (31).
10. Lighting unit (10) according to Claim 1, characterized in that the top surface (51) or the bottom surface (71) have at least two curved surface sections (72, 73) arranged offset to one another and rotated against one another around the intersecting line of the light entry surface (32) with the respectively oppositely arranged surface (71; 51).
11. Lighting unit (10) according to Claim 10, characterized in that the two surface sections (72, 73) are connected by means of a transitional area (75).
12. Lighting unit (10) according to Claim 11, characterized in that the transitional area (75) forms with the two surface sections (72, 73) an angle of 135 degrees in each case.
13. Lighting unit (10) according to Claim 10, characterized in that the longitudinal edges of the light guide body (31) which face away from the surface section (72, 73) have rounded portions (57).
14. Lighting unit (10) according to Claim 13, characterized in that the curvature radius of the rounded portions (57) increases in the light propagation direction (15).
15. Lighting unit (10) according to Claim 1, characterized in that a collimating lens (81) optically upstream of the secondary lens (91) is optically downstream of the light guide body (31).
16. Light guide body (31) having a light entry surface (32) and a light exit surface (34) and whose cross-section flares out in the light propagation direction (15), where two surfaces (51, 71) arranged opposite one another and limiting the light guide body (31), which in a longitudinal section bisecting these surfaces (51, 71) form a bottom surface (71) and a top surface (51), have opposingly curved sections (62, 76) adjoining the light entry surface (32), where the bottom surface (71) comprises a curved section (76) positively curved relative to the light propagation direction (15) and the top surface (51) a curved section (62) negatively curved relative to the light propagation direction (15), characterized in that

    - in the said longitudinal section at least one of the curves (62, 76) limiting the light guide body (31) has a reversal point (66).
17. Light guide body according to Claim 16, characterized in that the light exit surface (34) has at least seven times the size of the light entry surface (32).

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