Circuit assembly, lighting device, and vehicle headlight

Abstract

The invention relates to a circuit assembly (1) comprising a printed circuit board (2), at least one micromirror component (3) which is connected to the printed circuit board (2) for modulating a light beam oriented towards the micromirror component (3), a cooling body which is thermally connected to the at least one micromirror component (3), and a current regulating unit (5). The micromirror component (3) has a heating element (3a) which can be controlled by the current regulating unit (5), and the current regulating unit (5) is electrically connected to the heating element (3a) in order to actuate same. The current regulating unit (5) is additionally connected to the micromirror component (3) via a thermal connection to the cooling body (4) in order to transfer heat losses occurring on the current regulating unit (5).

Claims

1. A circuit assembly (1) comprising: a printed circuit board (2); at least one micromirror component (3) connected to the printed circuit board (2) and configured to modulate a light beam of a light source directed onto the micromirror component (3); a cooling body (4) thermally connected to the at least one micromirror component (3); a current regulating unit (5); a support frame configured to be connected to a vehicle headlight housing; and spring elements, wherein a heating element (3a) is assigned to the micromirror component (3), which heating element is configured to be controlled by the current regulating unit (5) and is thermally connected to the micromirror component (3), wherein the current regulating unit (5) is electrically connected to the heating element and configured to actuate the heating element, wherein the current regulating unit (5) is also connected to the cooling body (4) by way of a thermal connection to the micromirror component (3) and configured to transfer heat loss occurring at the current regulating unit (5), wherein the printed circuit board (2) is arranged between the cooling body (4) and the support frame (6), and the support frame (6) has positioning means (6a) configured to establish the position of the micromirror component (3) with respect to the support frame (6), wherein the cooling body (4) is connected to the support frame (6) by a screw connection (7) such that the printed circuit board (2) can be fixed in its position with respect to the support frame (6) by the cooling body (4), and the cooling body (4) can be relocated along the screw connection, and wherein the spring elements (8) press the cooling body (4) in the direction of the support frame (6).

2. The circuit assembly (1) according to claim 1, wherein the printed circuit board (2) has an opening (2a), through which a heat conduction element (4a) extends from the micromirror component (3) to the cooling body (4) for purposes of heat transfer.

3. The circuit assembly (1) according to claim 1, wherein the heating element (3a) is integrated into the micromirror component (3).

4. The circuit assembly (1) according to claim 1, wherein the current regulating unit (5) is arranged on the side of the printed circuit board (3) facing towards the cooling body (4).

5. The circuit assembly (1) according to claim 1, wherein the current regulating unit (5) is arranged on the side of the printed circuit board (3) facing away from the cooling body (4).

6. The circuit assembly (1) according to claim 5, wherein the current regulating unit (5) is thermally connected to the cooling body (4) by way of at least one heat conducting means (2b) extending through the printed circuit board (2), in particular at least one heat conducting via.

7. The circuit assembly (1) according to claim 1, wherein the current regulating unit (5) is a linearly regulated current regulating unit.

8. The circuit assembly (1) according to claim 1, wherein all electronic components (3, 5) of the circuit assembly (1) are SMD components.

9. The circuit assembly (1) according to claim 1, wherein at least one socket (9) is provided on the printed circuit board (2), for purposes of accommodating the at least one micromirror component (3).

10. The circuit assembly (1) according to claim 1, wherein the current regulating unit (5) is arranged at a maximum distance (d) of 3 cm from the micromirror component (3).

11. A lighting device, comprising: the circuit assembly (1) according to claim 1; a light source; and at least one imaging optic for purposes of imaging the light emitted by the lighting element into a predeterminable light distribution, wherein the light source, the micromirror component (3) and the imaging optics are arranged in such a way that light emitted by the light source can be deflected by way of the micromirror component (3) towards the at least one imaging optics.

12. A motor vehicle headlight comprising the lighting device according to claim 11.

Description

(1) The invention is explained in more detail below by means of exemplary and non-restrictive forms of embodiment, which are illustrated in the figures. Here:

(2) FIG. 1 shows a schematic representation of a circuit assembly according to the prior art,

(3) FIG. 2 shows a schematic representation of a first form of embodiment of a circuit assembly according to the invention,

(4) FIG. 3 shows a schematic representation of a second form of embodiment of a circuit assembly according to the invention,

(5) FIG. 4 shows an equivalent circuit diagram of an electrical circuit, consisting of a heating element of a microprojection element and a current regulating unit.

(6) In the following figures, unless otherwise indicated, identical reference symbols denote identical features.

(7) FIG. 1 shows a schematic representation of a circuit assembly 1′ according to the prior art. The circuit assembly 1′ comprises a printed circuit board, 2′, at least one micromirror component 3′, connected to the printed circuit board 2′, for purposes of deflecting a light beam directed onto the micromirror component 3′, together with a current regulating unit 5′. The micromirror component 3′ has an integrated heating element 3a′, which can be controlled by means of the current regulating unit 5′. The current regulating unit 5′ is located on the printed circuit board 2′, wherein no structural elements are provided for purposes of a thermal connection to the micromirror component 3′. The heat loss at the current regulating unit 5′ thus remains unutilised.

(8) FIG. 2 shows a schematic representation of a first embodiment of a circuit assembly 1 according to the invention. In an analogous manner to the inventive circuit assembly 1 comprises a printed circuit board 2, and at least one micromirror component 3 connected to the printed circuit board 2, for purposes of modulating a light beam directed onto the micromirror component 3. In addition, the circuit assembly 1 comprises a cooling body 4, which thermally connected to the at least one micromirror component 3, and a current regulating unit 5. The micromirror component 3 has an integrated heating element 3a, which can be controlled by means of the current regulating unit 5.

(9) In contrast to the circuit assembly 1′ according to the prion art, in the circuit assembly 1 the current regulating unit 5, which is electrically connected to the heating element 3a, is, according to the invention, thermally connected to the micromirror component 3 by way of a thermal connection to the cooling body 4, for purposes of transferring the heat loss occurring at the current regulating unit 5. For this purpose, the printed circuit board 2 in this example of embodiment has an opening 2a, through which a heat conduction element 4a extends from the micromirror component 3 to the cooling body 4 for purposes of heat transfer. The heat conduction element 4a in this example of embodiment is formed in one piece with the cooling body 4. Heat conducting material 10 (e.g. a heat conducting paste) can be arranged between the cooling body 4 and the printed circuit board 2 to improve the heat transfer. In particular, provision can be made for this heat-conducting material 10 (e.g. “Gapfiller” material from the company Bergquist GF1500) in particular to be designed for purposes of conduction over greater distances (in the millimetre range), wherein the material is arranged in the region between the printed circuit board 2 and the current regulating unit 5. This material can also be arranged between the micromirror component 3 and the heat conduction element 4a. Alternatively, a conventional heat conducting paste or heat conducting adhesive can be used for this purpose.

(10) The circuit assembly 1 further comprises a support frame 6 that can be connected to a vehicle headlight housing (not shown in the figures), wherein the printed circuit board 2 is arranged between the cooling body and the support frame 6. The support frame 6 comprises positioning means 6a designed as projections in order to establish the position of the micromirror component 3 with respect to the support frame 6.

(11) The electronic components of the circuit assembly are arranged both on the side of the printed circuit board 2 facing towards the support frame 6, and also on the side facing away, wherein the current regulating unit 5 is thermally connected to the cooling body 4 by way of at least one heat conducting means 2b, in particular heat conducting vias, extending through the printed circuit board 2.

(12) The cooling body 4 is connected to the support frame 6 in such a way that the printed circuit board 2 can be fixed in its position with respect to the support frame 6 by the cooling body 4. This is achieved in the present example of embodiment by connecting the cooling body 4 to the support frame 6 by means of a screw connection 7, wherein the cooling body 4 can be relocated along the screw connection 7, and spring elements 8 are provided, by means of which the cooling body 4 is pressed in the direction of the support frame 6.

(13) A socket 9 is arranged on the printed circuit board 2, which socket is provided to accommodate the micromirror component 3, and by way of which the micromirror component 3 is electrically connected to the printed circuit board 2.

(14) In order to transfer the heat loss occurring at the current regulating unit 5 as completely and quickly as possible to the micromirror component 3, provision can be made for the distance between the micromirror component 3 and the current regulating unit to be a maximum of 3 cm (as measured from the centres of the elements in the direction of the plane spanned by the printed circuit board 2).

(15) The invention also relates to a lighting device, not shown in detail in the figures, comprising a circuit assembly 1 according to the invention, a light source, together with at least one imaging optic (the light source and the imaging optic are not shown in the figures) for purposes of imaging the light emitted by the lighting element into a predeterminable light distribution, wherein the light source and the micromirror component are arranged in such a way that light emitted by the light source can be directed by way of the micromirror component to the imaging optics, in particular a projection device (a lens). The invention furthermore relates to a vehicle headlight, in particular a motor vehicle headlight, comprising a lighting device according to the invention, together with a vehicle comprising a vehicle headlight according to the invention, in particular a motor vehicle headlight.

(16) FIG. 3 shows a schematic representation of a second form of embodiment of a circuit assembly according to the invention 1. In contrast to the first form of embodiment, the current regulating unit 5 is arranged on the underside of the printed circuit board 2, wherein the cooling body 4 makes contact with the current regulating unit 5 directly on its housing by means of a heat conducting material.

(17) FIG. 4 shows an equivalent circuit diagram of an electrical circuit, consisting of the heating element 3a of a microprojection element 3, and a current regulating unit 5. The equivalent circuit shows a voltage source U.sub.0, by way of which the current regulating unit 5 and the heating element 3a are supplied. The voltage U.sub.0 is divided into the voltages U.sub.DMD and U.sub.SR, wherein the ratio of these voltages is predetermined depending on the nature of the heating element, the ambient temperature, as well as the properties of the regulator 5 and its operating state. As already mentioned in the introduction, the power dissipation at the controller 5 may well assume the same values as the heat output of the heating winding. In this case U.sub.SR=U.sub.DMD therefore applies, wherein the power dissipation P.sub.SR=I.sub.Heater*U.sub.SR, and P.sub.DMD=I.sub.Heater*U.sub.DMD. In that, according to the invention, the power dissipation P.sub.SR occurring at the current regulating unit 5 is used to heat the micromirror component 3, the heating power P.sub.DMD and thus the total energy requirement for heating the micromirror component 3 can be reduced.

(18) In view of this teaching, the person skilled in the art is able to arrive at other, not shown, embodiments of the invention without any inventive step. Individual aspects of the invention or the embodiment are taken up and combined with each other. Any reference symbols in the claims are exemplary, and serve only to make the claims easier to read, without restricting them.