WO2015155241A1

WO2015155241A1 - Device for holding an optical component

Info

Publication number: WO2015155241A1
Application number: PCT/EP2015/057621
Authority: WO
Inventors: Benno Spinger; Ralph Hubert Peters
Original assignee: Koninklijke Philips N.V.
Priority date: 2014-04-10
Filing date: 2015-04-08
Publication date: 2015-10-15

Abstract

The present invention relates to a holding device for an optical component, in particular to a lens holder for a headlamp projection lamp. The device comprises a base (1), a lower holding portion (3), comprising a first opening for the passage of light from a light source (8), and an upper holding portion (2) having a second opening for the passage of the light from the light source (8) through the optical component (6). The lower holding portion (3) is mounted on the base (1) and comprises an upper locating surface (7) for the optical component (6). The upper holding portion (2) is also mounted on the base (1) and comprises a soft element (5) which is arranged between a protrusion (4) of the upper holding portion (2) and said optical component (6) to press the optical component (6) against the locating surface (7). With the proposed device tolerances of the optical component are compensated by the soft element while at the same time the optical component is exactly referenced against a reference object through the lower holding portion without being over determined.

Description

Device for holding an optical component

BACKGROUND OF THE INVENTION

The present invention relates to a device for holding an optical component, in particular to a lens holder for a headlamp projection lamp.

Optical components of lamps or other optical systems often require appropriate holders for exactly defining the position and orientation of the optical component. In particular when using lenses for collimation of light emitted by a light source the exact distance of the lens to the light source is essential. The exact distance may be guaranteed by the referencing of the lens holder against the light source. Molding of big lens elements however will result in geometrical variations due to inconsistent shrinkage of the material - especially for glass. Over the complete element this can be several 100 μιη.

For mechanical reasons the lens needs to be hold close to the balance point - typically the bigger part of the lens - where the highest shrinkage occurs. On the other hand, especially when using a pre-collimation element (primary optics) a high positional accuracy relative to the light source is required. If the lens is referenced against the light source and the light source is referenced against the main lens holder, the resulting system would be over determined.

EP 2423570 discloses a LED light module with the LED light source mounted at the base. A base ring is mounted on the same base and is configured to receive an optical component. The optical component is positioned to receive light from the LED light source. The optical component includes a plurality of posts that extend through holes in the base for centering the optical component with respect to the LED light sources. The LED light module further comprises a top cover and a compression ring that presses the optical component in the direction of the base.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a device for a holding an optical component, in particular a lens holder, which in spite of geometrical tolerances of the optical component allows an easy mounting and referencing of the optical component against a reference object without over determination. The object is achieved with the device for holding an optical component according to claim 1. Advantageous embodiments of the device are subject of the dependent claims or are described in the subsequent portions of the description and preferred embodiments.

The proposed device comprises a base, a lower holding portion having a first opening for the passage of light from a light source - which may be mounted on the base - through the optical component and comprising an upper locating surface for the optical component, and an upper holding portion having a second opening for the passage of light from the light source through the optical component. Said lower holding portion is mounted on the base to provide a fixed distance between the upper locating surface and the base. The upper holding portion is also mounted on the base. The upper holding portion comprises one or several protrusions extending towards the optical component and also comprises a soft element between said protrusion and said optical component to hold or press said optical component with the upper holding portion against the locating surface.

The proposed holding device therefore comprises two different holding portions for the optical component. The lower holding portion takes care of the correct referencing of the optical component against a reference object on the base, e.g. a base plate or a base frame. The upper holding portion is designed to hold the optical component close to its balance point or center of gravity. The soft element at this upper holding portion compensates the tolerances of the optical component which may be caused by the production process of this component.

In a preferred embodiment the optical component is a lens or a lens system with a big main lens and a smaller pre-collimating optics. The upper holding portion thus compensates the big tolerances of the main lens by the soft material and at the same time achieves an exact referencing of the smaller pre-collimating optics by means of the lower holding portion. The light source is mounted on the base. The main lens and the pre- collimating optics may be formed integrally in one single body, may be attached to one another or may be fixed relative to each other with a corresponding frame. Nevertheless, since the pre-collimating optics is exactly referenced against the light source by the lower holding portion which is mounted on the base, and the main lens is held by the upper holding portion with the soft material compensating for geometrical tolerances, the whole lens system can be easily mounted and is not over determined.

Preferably the upper locating surface is appropriately formed to center the counter part of the optical component or element, e.g. the pre-collimating optics. This centering can be achieved, for example, by appropriate grooves in the locating surface into which corresponding protrusions, e.g. half spheres, on the surface of the optical component facing the locating surface engage.

The upper and lower holding portions may be formed for example from a metal. The soft material may be made of a soft polymer or a gum, e.g. in the shape of an O- ring. The proposed device is preferably formed as a lens holder for a headlamp projection lens, where the light source is mounted on the base. Nevertheless, the device may also be used for other optical components which show geometrical tolerances and have to be referenced against a reference object.

BRIEF DESCRIPTION OF THE DRAWINGS

The proposed device is described in the following by way of examples in connection with the accompanying figures. The figures show:

Figure 1 a cross-sectional view of a lens system mounted in a holding device according to a first example of the invention;

Figure 2 a view of portions of the device of figure 1 for centering the lens system; and

Figure 3 a cross-sectional view of the proposed device with a mounted lens system according to a further embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 shows a cross sectional view of an example of the proposed holding device for holding a lens system as the optical component. The holding device in this example comprises a base plate 1, an upper holding portion 2, in the following also called main lens holder, and a lower holding portion 3, in the following also called second lens holder. The main lens holder 2 is mounted on the base plate and comprises a circumferential protrusion 4 and a corresponding soft element 5 working as a soft interface for holding the lens 6 close to its center of gravity or balance point. The second lens holder 3 is also mounted on the base plate 1 and comprises an upper locating surface 7 for the lens 6. Due to the mounting of this second lens holder 3 on the base plate 1, the locating surface 7 is in a well- defined distance to the surface of the base plate 1. A light source 8, typically a LED, is mounted together with the underlying LED-chip 9 on the base plate. The upper locating surface 7 guarantees an exact referencing to enable highly accurate alignment of the lens 6 relative to the light source 8. The second lens holder 3 has a corresponding opening in the center to allow passage of the light from the light source 8 through the lens 6. The soft element 5 on the other hand is situated at the lens area where it has the highest tolerance due to the fabrication process. This soft element 5, which is preferably an elastic element, will create a force in direction of the real reference system, i.e. the second lens holder 3 with the locating surface 7 , which is situated relatively close to the light source 8.

With such a holding device the large tolerances of the lens or lens system close to its region of largest extension are compensated by the soft material of the soft element 5 in the main lens holder. The smaller tolerances of the lens or lens system close to the light source at the entrance of the pre-collimation part or optics of the lens system are used for referencing at the second lens holder. The light source is referenced to the main and to the second lens holder since all these components are mounted on the base plate.

The lens 6 in this example is composed of several lens parts. These parts are typically attached to one another by means of an appropriate glue. The part close to the light source is designed to pre-collimate the light from the light source, and the big part close to the main lens holder collimates the pre-collimated light from the pre-collimation part. Close to the balance point of the lens 6 two lens parts can be recognized in this example, which form a circumferential rim around the lens. This rim is used to engage with the protrusion 4 of the main lens holder 2 through the soft element 5. Nevertheless, the lens 6 may also have another appropriate outer shape which allows to hold the lens by means of the protrusion 4 and soft element 5 such that it is at least softly pressed against the locating surface 7 of the second lens holder 3. The soft element 5 may be fixed to the main lens holder or may also be a separate element which is inserted during mounting of the lens 6.

In a preferred embodiment, the second lens holder 3 provides means for centering the lens 6. This may be achieved by an appropriate shape of the locating surface 7 of the second lens holder 3. Figure 2 shows an example of such a shape in which 3 V-grooves 10 are arranged at the locating surface 7. These V-grooves 10 extend radially from the center of the second lens holder and are separated by an angle of 120° as can be seen in the figure. The lens 6 comprises 3 corresponding engaging elements 11 in the shape of half- spheres which engage in these V-grooves when mounting the lens in the lens holder. The half-spheres 11 are also indicated in figure 1 and figure 3. Due to the V-grooves 10 and the corresponding half-spheres 11 a self-centering system is realized so that the lens is automatically centered when it is mounted in the holding device.

Figure 3 shows a further example in which the lens system is composed of two separate lenses 12, 13. In this example, the pre-collimation lens 13 is not attached to the main lens 12. Both lenses 12, 13 are realized as separate lens elements which are fixed to each other by a frame 14. The alignment of the main lens 12 to the pre-collimation lens 13 will result in an additional contribution to the tolerance chain. With the proposed holding device, however, still a small tolerance for referencing the pre-collimation lens 13 against the light source 7 is achieved. The holding device in this example can be realized identical to the holding device described in connection with figures 1 and 2.

With the proposed device a lens holder for a headlamp protection system can be realized where the pre-collimation unit is attached to or is part of the main lens. The big tolerances of the main lens are compensated by a soft material in the main lens holder and the small tolerance close to the light source at the entrance of the pre-collimation unit is captured by a second lens holder part referenced to the light source. The light source again is referenced to the main lens holder. The soft material in the main lens holder compensates the otherwise over determined system tolerances.

While the invention has been illustrated and described in detail in the drawings and forgoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiment. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures can not be used to advantage. In particular, claims 2 to 8 can be freely combined. Any reference signs in the claims should not be construed as limiting the scope of the invention.

LIST OF REFERENCE SIGNS

1 base plate

2 upper holding portion/main lens holder

3 lower holding portion/second lens holder

4 protrusion

5 soft element

6 lens system

7 locating surface

8 light source

9 chip

10 V-grooves

1 1 half spheres

12 main lens

13 pre-collimating lens

14 frame

Claims

CLAIMS:

1. A device for holding an optical component, comprising

- a base (1) configured to mount a light source (8);

- a lower holding portion (3) mounted on said base (1) and having a first opening for the passage of light from the light source (8), the lower holding portion (3) comprising an upper locating surface (7) configured to locate the optical component (6) and to provide a fixed distance between said upper locating surface (7) and said base (1);

- an upper holding portion (2) mounted on said base (1) and having a second opening for the passage of light from the light source (8), said upper holding portion (2) comprising at least one protrusion (4) configured to receive an elastic element (5), the elastic element (5) being configured to press said optical component against the locating surface (7); wherein the lower holding portion (3) is configured to center the optical component (6).

2. The device according to claim 1,

characterized in that said upper locationg surface (7) comprises grooves (10) for centering the optical component (6).

3. The device according to claim 2,

characterized in that three grooves (10) are provided and that the grooves (10) radially extend with an angle of 120° between the grooves (10).

4. The device according to claim 2,

characterized in that the grooves (10) are configured to receive engaging elements (11) of the optical component (6) .

5. The device according to claim 4,

characterized in that that the grooves (10) are configured to receive engaging elements (11) of the optical component (6), which engaging elements are half-spheres.

6. The device according to claim 1,

characterized in that said elastic element (5) is an elastic O-ring.

7. The device according to claim 1,

characterized in that the device is configured to hold an optical component (6) comprising a circumferential rim,

wherein the protrusion (4) and the elastic element (5) are configured to press said optical component (6) by the circumferential rim against the locating surface (7).

8. The device according to claim 1,

characterized in that the device is configured to hold the optical component (6) such that a balance point or center of gravity of said optical component (6) is arranged closer to the protrusion (4) of the upper holding portion (2) than to the locating surface (7).

9. The device according to claim 8,

characterized in that the device is configured to hold an optical component (6) comprising at least a main lens (12) and a pre-collimating optics (13), said pre-collimating optics (13) pre- collimating the light from the light source (8) and said main lens (12) having a larger diameter than the pre-collimating optics (13).

10. The device according to claim 9,

characterized in that the device is configured to hold the optical component (6) of which said main lens (12) and said pre-collimating optics (13) are attached to each other or integrally formed in one single lens body.

11. The device according to claim 9,

characterized by that the device comprises a fixing frame (14) that holds a seperate main lens (12) and a seperate pre-collimating optics (13) of the optical component (6).

12. Optical component (6) suitable for use in the device according to any of the claims 1-11.