EP2297515B1 - Retaining frame having at least one optical element - Google Patents

Description

The invention relates to a mounting frame with at least one optical element attached thereto, a method for mounting an optical element to a mounting frame and a lighting device, in particular a vehicle headlamp module, with a mounting frame.

US 2005/0128762 A1 describes a lighting device comprising a lens carrier and a glass lens configured to be located in front of a light source, wherein the lens (a refractive imaging optical element) is assembled with the lens carrier attached to the light source Carrier is made of a plastic material, wherein the lens has a back, which is adapted to point in the direction of the light source, and an optical front and a peripheral edge, which connects the back and the front with each other, wherein the lens carrier at the edge in Engages the lens, wherein the lamp is characterized in that the carrier is attached to the lens by means of extrusion coating, wherein the material of which the carrier consists, at least partially surrounds the edge of the lens.

The EP 0 961 074 A2 discloses a lighting device for vehicles with a frame-like cover member and a cover integrally made therewith by injection molding of plastic. The EP 0 892 209 A2 discloses a lens for a vehicle headlamp with a plastic injection molding method fixed thereto seal.

It is the object of the present invention to provide a further possibility for mounting an optical element, in particular for a lighting device, in particular while further reducing the load on the optical element to be picked up.

This object is achieved by means of a mounting frame, by means of a method for producing a system of mounting frames and an optical element attached thereto, and by means of a lighting device, in particular a vehicle headlight module, solved according to the respective independent claim. Preferred embodiments are in particular the dependent claims.

The support frame is equipped with at least one attached thereto by means of an injection molding optical element, wherein the at least one optical element for beam shaping is formed at least by means of total internal reflection and / or diffraction. An optical element with at least total internal reflection and / or diffraction is understood to mean an optical element whose beam guidance is based on total internal reflection and / or diffraction, but can additionally also be based on refraction.

It is particularly preferred if the at least one optical element has a CPC-like region, a CEC-like region and / or a CHC-like region. In particular, a CPC-type concentrator may be used, by which is meant a concentrator whose reflective sidewalls have at least partially and / or at least largely the shape of a compound parabolic concentrator (CPC). Also z. For example, a compound elliptic concentrator (CEC) and / or a composite hyperbolic concentrator (CHC) may be employed.

Particularly preferred is the use of a free-form concentrator. A concentrator may, especially when used as a primary optic in a vehicle headlamp module, preferably serve to throw light from a light source to a secondary optics while adjusting a light distribution pattern, e.g. B. to create a light / dark boundary.

Alternatively or additionally, however, it may also be preferred if the optical element has a truncated pyramid-like region or a frustoconical region.

The optical element preferably has at least two projections for mechanically good-natured attachment to the mounting frame, in particular laterally arranged projections. Preferably, the provision of exactly two projections at opposite positions. It is particularly preferred for reducing transmission of mechanical and / or thermal stresses when the protrusions are arranged on only a minor part of a circumference of the optical element

It is particularly preferred if the projections are held by means of a marginal, in particular narrow, overhang on the support frame.

Particularly preferred is a support frame, which consists of a plastic, in particular a thermoplastic material, especially PPS ("polyphenylene sulfide", also called "poly (thio-p-phenylene)"), especially linear PPS. The good mechanical properties of PPS are maintained even at temperatures well above 200 ° C, so that a continuous use, depending on the load up to 240 ° C is possible. For a short time, loads at temperatures of up to 270 ° C are withstood. Also outstanding is the chemical resistance to almost all solvents, many acids and alkalis as well as to atmospheric oxygen even at high temperatures. In addition to low water absorption, PPS also has good dimensional stability and inherent flame retardancy. It has excellent electrical insulating properties, is highly impermeable to most liquids and gases, has low creep even at higher temperatures and, due to its good flow, is also suitable for long, narrow moldings and complex tool geometries. Linear PPS can, unlike cross-linked PPS, they are formed into components through a wide range of processing techniques.

It is for particularly effective reduction of stray light, a support frame is preferred in which an inner side of the wall, which is intended to be directed towards the optical element, having a light-absorbing surface structure.

For this purpose, the wall may, for example, be roughened and / or coated with a light-absorbing layer.

It is also preferred for the effective and all-round reduction of stray light, a support frame having a closed circumferential wall for laterally surrounding the optical element.

The method for producing a system of support frame and an optical element attached thereto comprises at least the step of injection molding the support frame, wherein the optical element is potted only at a plurality of mounting protrusions with the support frame, in particular by means of a marginal overhang.

In a further step, the support element can then be connected directly or via further means, such as circuit carrier, heat sink or substrate plates, with the light source.

The lighting device is equipped with such a mounting frame and has at least one semiconductor light source, in particular light-emitting diode, on which the optical element is connected downstream, in particular as primary optics.

The optical element may be made of glass or transparent plastic, preferably silicone.

FIG 1

zeigt als Explosionsdarstellung in Schrägansicht von oben einen Rahmen gemäß für ein optisches Element mit einem darin zu halternden optischen Element getrennt davon;

FIG 2

zeigt in Schrägansicht von oben das System aus FIG 1 mit dem optischen Element mit dem Rahmen befestigt;

FIG 3

zeigt als Schnittdarstellung in Seitenansicht eine Beleuchtungsvorrichtung mit einem System nach FIG 2.

In the following figures, the invention will be described schematically with reference to an embodiment schematically. It can be provided with the same reference numerals for better clarity identical or equivalent elements.

FIG. 1

shows an exploded view in an oblique view from above of a frame according to an optical element with an optical element to be held therein separated therefrom;

FIG. 2

shows in an oblique view from above the system FIG. 1 attached to the frame with the optical element;

FIG. 3

shows a sectional view in side view of a lighting device with a system FIG. 2 ,

FIG. 1 shows an optical system 1 with a support frame 2 and to be attached to the frame optical element 3 in an exploded view. The optical system 1 is typically connected downstream of one or more light sources and serves for beam guidance of at least part of the light emitted by the light source or the light sources. The optical system 1 can be used for example as part of an automotive lamp, z. B. a headlight.

The support frame 2 has a hollow, upper side and lower side open base body 4, which is formed by means of a closed circumferential, thick wall 5 with a substantially oval passage contour. The thus formed inner cavity 6 of the base body 4 serves to receive the optical element 3. For this purpose, the base body 4 at its upper edge 7 has two receiving areas in the form of opposing recesses 8. In a lower region of the main body 4 are four laterally protruding tabs 9, 10 for attachment of the support frame 2 at one, not shown here, light available. To guide the support frame 2, two obliquely opposite tabs 9 perpendicular guide pins 11, whose lower part is used for positioning of the support frame 2 and whose upper part is used for positioning a secondary optics. The other two tabs 10 have through holes 12 for the implementation of fastening screws.

The support frame 2 is made of linear PPS. The PPS is blackened to minimize light reflection on the support frame 2. As a result, unwanted scattered light which impinges on the support frame 2 can be suppressed. For further suppression of light reflection on the support frame 2, the inner side 13 of the main body 4 or its wall 5 is roughened. A lateral leakage of stray light from the support frame 2 is also suppressed by the closed circumferential shape of the wall 5.

The optical element 3 is designed as a totally internal reflection (TIR) optic with an asymmetrically truncated pyramid base body 14 made of glass. Such a designed primary optic allows an efficient reduction of the divergence of light, which can be achieved in particular headlights with sufficient brightness and well-defined radiation characteristics.

For attachment to the support frame 2, the optical element 3 has a corresponding attachment region with two lateral tab-shaped projections 15. The projections 15 have essentially the attachment function and have only a negligible influence on the optical property of the optical element 3. An advantage of the attachment only to the projections 15 is also that then a cut-off line is well defined. The optical element 3 is thus fixed only by the projections 15 on the support frame 2, while the remaining surface free is. By virtue of the protrusions 15 occupying a circumferentially small portion of the optical element 3 (namely, being located only on the narrow sides of the upper edge), mechanical stress on the protrusions, which could be caused by assembly, has little effect on the protrusion remaining volume of the optical element 3, since distortions in the material can be at least partially degraded by the free surface. This "load goodness" is the more pronounced the fewer projections 15 are used and the smaller the relative attachment area.

It should be noted that the optical system 1 is produced by injection molding of the support frame 2, the support frame 2 and the optical element 3 are thus not intended to be separated.

FIG. 2 shows the optical system 1 with the support frame 2 and the optical element 3 connected together. This is done by injection molding the support frame 2 to the optical element 3. Since the TIR element 3 on the upper side with the upper edge 7 of the support frame 2 is substantially flush, sets a narrow, marginal camber 19 directly above the projection 15 of the optical TIR element 3 and holds the optical element 3 on the support frame. 2

Compared to a completely circumferential attachment, z. B. by means of a circumferential mounting edge, resulting from the edge only partially present projections 15, first, the advantage that the thermal load of the optical element 3 is far lower and secondly, the connection is easier spray-injection. This is supported by the only narrow overhang 19. As a result, even a silicone optical element may be used.

The surface of the optical element 3 outside the protrusions 15 is not in contact with the support member 2. When viewed along the inner cavity 6 from above or below remains a free to the projections 15 circumferentially free space between the optical element 3 and the support frame 2. The optical element 2 thus does not close the inner cavity 6. By this "loose" arrangement, it is possible to use variously shaped optical elements (concentrators, diffraction gratings, etc.) in the same support frame 2.

FIG. 3 shows the lighting device with a system according to FIG. 2 in cross section. This view shows that the optical element 3 (TIR concentrator) is not symmetrical. Thus, the two side walls 20 are different obliquely, wherein nevertheless along them direct connecting lines between a lower light entrance surface 21 and an upper light exit surface 22 are substantially straight. Furthermore, above the truncated pyramid-shaped region 23 of the optical element 3, a non-widening extension region 24 adjoins, on which also the lateral tabs are arranged. The bulges 19 hold the optical element 3 at the edge of the upper light exit surface 22. The optical element 3 is laterally completely surrounded by the support frame 17 along its longitudinal extent (parallel to the z-axis). It can be seen from the cross-sectional illustration shown here on the narrower side of the optical element 3 that the optical element 2 fills less than a third of the inner cavity 6, but over almost its entire length (along the z-direction).

In operation, light from a light-emitting diode 25 is fed into the lower light entry surface 21 of the optical element 3, as is merely outlined here. The light-emitting diode 25, which is constructed here from a plurality of mounted on a common submount white-emitting LED chips is arranged so close to the lower light entrance surface 21, that radiated by her light for the most part enters the lower light entrance surface 21 and only a small Part up the inside 13 of the wall 5 of the support frame 2 is blasted. No light from the LED 25 is transmitted directly through the free space between the optical element 3 and the wall 5. The light-absorbing property of the inner side 13 absorbs incident light thereon. Thus, only the optical element 3 light is emitted to the outside (here: up). More specifically, light entering the lower light entrance surface 21 either passes directly through the optical element 3 to the upper light exit surface 22, from where it is re-emitted; or light rays incident on the side walls 20 of the optical element 3 are reflected back into the optical element 3 by means of total internal reflection (TIR). This results in a desired illumination pattern with only low radiation losses.

Of course, the present invention is not limited to the embodiments shown.

Thus, instead of PPS, another, preferably thermoplastic, plastic can be used. This is preferably opaque.

The type of optical element is not limited. Instead of the TIR concentrator having a substantially truncated pyramidal structure, it is also possible, for example, to use a substantially frusto-conical basic shape.

Instead of a TIR concentrator but z. B. also a freeform, CPC, CEC or CHC-type concentrator can be used.

It is also possible to use a combined concentrator / diffractive optic, e.g. B. by diffractive structures are applied to a concentrator.

Also, general deflection prisms can be used.

Alternatively, in particular, diffractive optical elements, such as a Fresnel zone plate or a diffraction grating, can also be held in the mounting frame.

The optical element may have a microstructured surface for beam shaping, e.g. B. a so-called cushion structure.

The number of attachment areas, in particular attachment projections, of the optical element is not limited. Thus, more than two attachment areas may be present, or only a single receiving area, for example in the form of a partially or completely circumferential edge.

Preferably, the semiconductor light source comprises at least one light-emitting diode. The light source can be present, for example, as an LED module with a light-emitting diode chip or a plurality of light-emitting diode chips, or as a single (s) housed (s) LED ('LED lamp'), which preferably emits white, z. B. a conversion LED. In the presence of several LEDs, these z. B. same color (monochrome or multi-colored) and / or different colors shine. Thus, an LED module may have a plurality of single LED chips ('LED cluster'), which together result in a white mixed light, z. B. in 'cold white' or 'warm white'. To produce a white mixed light, the LED cluster preferably comprises light-emitting diodes which shine in the primary colors red (R), green (G) and blue (B). In this case, single or multiple colors can also be generated by several LEDs simultaneously; Combinations RGB, RRGB, RGGB, RGBB, RGGBB etc. are possible. However, the color combination is not limited to R, G and B, but may include, for example, white-emitting LED chips. For example, one or more amber LEDs 'amber' (A) may also be present to produce a warm white hue. An LED module can also have several white single chips, resulting in a simple scalability of the luminous flux can achieve. The individual chips and / or the modules can be equipped with suitable optics for beam guidance, z. B. Fresnel lenses, collimators, and so on. It can be arranged on a contact several identical or different types of LED modules, for. B. several similar LED modules on the same substrate. Instead of or in addition to inorganic light emitting diodes, z. B. based on InGaN or AlInGaP, organic LEDs (OLEDs) are generally used. Also z. B. diode lasers are used.

LIST OF REFERENCE NUMBERS

1

optical system

2

support frame

3

optical element

4

body

5

wall

6

inner cavity

7

upper edge

8th

deepening

9

flap

10

flap

11

guide pin

12

Through Hole

13

Inside of the wall

14

Basic body of the optical element

15

head Start

19

vaulting

20

Side wall

21

lower light entry surface

22

upper light exit surface

23

truncated pyramidal portion of the optical element

24

extension area

25

led

Claims (8)

1. Retaining frame (2) having at least one optical element (3) attached thereto using an injection moulding method, characterized in that the at least one optical element (3) is configured for beam shaping at least by way of total internal reflection and/or diffraction and has at least two protrusions (15) for attachment with the retaining frame (2) and the at least two protrusions (15) are held on the retaining frame (2) by way of a peripheral bulge (19).
2. Retaining frame (2) according to Claim 1, in which the optical element (3) has a free-form concentrator-type region, a CPC-type region, a CEC-type region and/or a CHC-type region.
3. Retaining frame (2) according to Claim 1 or 2, in which the optical element (3) has a region like a truncated pyramid or a region like a truncated cone.
4. Retaining frame (2) according to one of the preceding claims, having a closed circumferential wall (5) for laterally enclosing the optical element (3).
5. Retaining frame (2) according to Claim 4, in which an inner side (13) of the wall (5), which is provided so as to face the optical element (3), has a light-absorbing surface structure.
6. Retaining frame (2) according to one of the preceding claims, which is made of a thermoplastic.
7. Illumination apparatus having a retaining frame (2) according to one of the preceding claims, having at least one semiconductor light source (25), downstream of which the optical element (3) is connected.
8. Method for producing a system of a retaining frame (2) and of an optical element (3) attached thereto, characterized in that the method has at least the following step:

   injection moulding the retaining frame (2) such that the optical element (3) is moulded together with the retaining frame (2) only at a plurality of attachment protrusions (15) by way of a peripheral bulge (19).

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