Area light modulator

Abstract

A surface light modulator (SLM) comprising a printed circuit board (1) provided with conductor tracks for contacting a DMD chip (2), wherein the DMD chip (2) is supported under bias on its side facing the printed circuit board (1) with its circumferential edge (5) on a housing (4) which has an opening (6) leaving the area of ​​the DMD chip (2) enclosed by the circumferential edge (5) free, wherein the DMD chip (2) is optionally supported with its other side on one side of the printed circuit board (1) via an interposer (3), with a heat dissipation element (9) arranged on the side of the printed circuit board (1) opposite the DMD chip (2), and wherein the package consisting of the printed circuit board (1), optionally the interposer (3) and the DMD chip (2) is held to the housing (4) by a screw connection between the heat dissipation element (9) and the housing (4), and wherein the printed circuit board (1) and possiblyThe interposer (3) each have a through-opening (8) through which a heat dissipation block (10) of the heat dissipation element (9) projects, wherein the heat dissipation element (9) is subjected to a spring force such that the heat dissipation block (10) with its end face facing the DMD chip (2) is held in contact with the DMD chip (2) under spring preload, characterized in that the heat dissipation element (9), the circuit board (1), the DMD chip (2) and optionally the interposer (3) are connected to each other to form a pre-assembly unit, in which the heat dissipation block (10) with its end face facing the DMD chip (2) is held in contact with the DMD chip (2) under spring preload and the pre-assembly unit can be connected to the housing (4).

Description

[0001] The invention relates to a surface light modulator (SLM) with a printed circuit board which is provided with conductor tracks for contacting a DMD chip, wherein the DMD chip is supported under prestress on its side facing the printed circuit board with its peripheral edge on a housing which has an opening leaving the area of ​​the DMD chip enclosed by the peripheral edge free, wherein the DMD chip is supported with its other side, optionally via an interposer, on one side of the printed circuit board, with a heat dissipation element which is arranged on the side of the printed circuit board opposite the DMD chip and wherein the package comprising the printed circuit board, optionally the interposer and the DMD chip is held on the housing by a screw connection between the heat dissipation element and the housing.

[0002] In such a spatial light modulator (SLM), the DMD chip (DMD Digital Micromirror Device) must be pressed against the housing, and the DMD chip must be cooled on its contact side facing the circuit board. If an interposer is present, the electrical connection between the DMD chip and the circuit board is established via contact springs.

[0003] US 7 072 184 B2 shows a surface light modulator with a heat dissipation element according to the preamble of claim 1. US 2009 / 0 135 564 A1 and US 7 605 962 B2 also show surface light modulators with a heat dissipation element.

[0004] The object of the invention is to provide a surface light modulator of the type mentioned above, which is simple and has a few components and enables good heat dissipation from the DMD chip.

[0005] This object is achieved according to the invention by the characterizing features of claim 1. The circuit board and, if applicable, the interposer each have a through-opening through which a heat dissipation block of the heat dissipation element protrudes, wherein the heat dissipation element is acted upon by a spring force such that the heat dissipation block, with its end face facing the DMD chip, is held in contact with the DMD chip under spring preload.

[0006] This design ensures that the heat dissipation block is held securely in place on the DMD chip by the spring preload.

[0007] If an interposer is present, its contact force is also applied by the same spring preload.

[0008] The heat dissipation block can be designed with a relatively large cross-section, ensuring good heat dissipation. The part of the heat dissipation element located on the side of the circuit board facing away from the DMD chip can be designed with a large surface area, allowing the heat to be dissipated effectively into the environment over a large surface area of ​​the heat dissipation element.

[0009] The heat dissipation element, the circuit board, the DMD chip and, if applicable, the interposer are connected to one another to form a pre-assembly unit in which the heat dissipation block is held in contact with the DMD chip with its end face facing the DMD chip under spring preload and the pre-assembly unit can be connected to the housing.

[0010] This simplifies the installation of the area light modulator.

[0011] In order to dissipate the heat of the DMD chip effectively into the heat dissipation block, a thermal paste or a thermally conductive film, which can consist of a particularly curable elastomer, can be arranged between the end face of the heat dissipation block and the DMD chip.

[0012] The DMD chip can have touch contact elements that are held in contact with the conductor tracks of the circuit board with a certain force.

[0013] This particular force is so high that the DMD chip can still be moved parallel to the circuit board in order to align it with a light beam guided through the area modulator.

[0014] A simple and space-saving design is achieved by the fact that the heat dissipation element has several spring arms that project freely parallel to the circuit board, the free ends of which are connected to the housing by the screw connection and by which the heat dissipation block is held in contact with the DMD chip under prestress.

[0015] Since separate spring loading of the DMD chip against the housing and the heat dissipation element on the DMD chip are no longer required, the required components, installation space, weight, and assembly effort are reduced. This also reduces the possibility of assembly errors and keeps the costs of the area light modulator low.

[0016] To reduce the number of components and assembly effort, the heat dissipation element can have several rigid arms or second spring arms projecting parallel to the circuit board, the free ends of which can be connected to a counter element by a second screw connection, which, with several support points, applies prestress to the DMD chip against the end face of a stabilization plate facing the DMD chip.

[0017] If the heat dissipation element has several spring arms projecting parallel to the circuit board, the free ends of which are connected to the housing by a screw connection, which holds the pre-assembly unit in contact with second support points of the housing under preload, this preload serves only to secure the assembly unit to the housing. This allows the preload to be kept so low that the DMD chip can be easily moved parallel to the circuit board to align it with a light beam guided by the area modulator.

[0018] The spring arms and / or the rigid arms or second spring arms can preferably be arranged uniformly distributed around the heat dissipation element and thus generate a spring force directed in the direction of movement of the heat dissipation block.

[0019] The spring arms and / or the rigid arms or second spring arms can be arranged at the end region of the heat dissipation block opposite the DMD chip at a distance from the plane of the circuit board.

[0020] Separately mounted spring elements are not required if the spring arms and / or the rigid arms or second spring arms are formed as one piece with the heat dissipation element.

[0021] For good heat dissipation, the heat dissipation element and, if applicable, the spring arms and / or second spring arms can be made of a metal with good heat conduction, in particular aluminum or an aluminum alloy.

[0022] In order to avoid electrical contact between the heat dissipation element and the conductor tracks of the circuit board, the heat dissipation element can be attached to the circuit board via an insulating layer, whereby the insulating layer is preferably an insulating film for easy assembly.

[0023] Embodiments of the invention are illustrated in the drawings and described in more detail below. They show: Fig. 1 a perspective sectional view of a first embodiment of a surface light modulator Fig. 2 a perspective sectional view of a second embodiment of a surface light modulator.

[0024] The illustrated area light modulators comprise a printed circuit board 1 with conductor tracks (not shown) arranged thereon for contacting, as well as with electrical and electronic components arranged thereon for controlling a DMD chip 2. The DMD chip 2 is supported on one side by its circumferential edge 5 at second support points 21 on a housing 4. The circumferential edge 5 encloses the active part of the DMD chip 2. Corresponding approximately to the area enclosed by the circumferential edge 5, the housing 4 has an opening 6, which is covered by an optical element 7.

[0025] An interposer 3 is arranged between one side of the circuit board 1 and the DMD chip 2, via which contact is made between the DMD chip 2 and the conductor tracks of the circuit board 1.

[0026] A through-opening 8 is formed in the printed circuit board 1, aligned with the opening 6 of the housing 4.

[0027] An aluminum heat dissipation element 9 arranged on the side of the circuit board 1 facing away from the DMD chip 2 has a heat dissipation block 10, which rests against the DMD chip 2 with its end face facing the DMD chip 2. A gap existing between this end face of the heat dissipation block 10 and the DMD chip 2 is filled with a cured thermal paste 11.

[0028] On the side of the circuit board 1 facing away from the DMD chip 2, the heat dissipation element 9 has two stabilization plates 12, 13 extending parallel to one another and parallel to the circuit board 1, which are connected to one another by the heat dissipation block 10 and form a large heat dissipation surface.

[0029] The stabilization plate 13, which is further away from the circuit board 1, has several pairs of first spring arms 14, the spring arms of one pair extending diametrically to each other.

[0030] The free ends of the first spring arms 14 are curved toward the circuit board 1 and have holes at their free end areas. Screws 15 protrude through these holes, which are guided through corresponding through-holes in the circuit board 1 and screwed into threaded holes in the housing 4.

[0031] On the side of the circuit board 1 facing away from the DMD chip 2, an insulating film 16 is arranged between the circuit board and the heat dissipation element 9 and its spring arms 14.

[0032] In the embodiment of the Fig. 1, in which no pre-assembly unit according to claim 1 is shown, the heat dissipation element 9 with its heat dissipation block 10 is clamped against the DMD chip 2 by the screws 15 screwed into the threaded holes of the housing 4 via the spring arms 14, so that the heat dissipation block is in contact with the DMD chip 2 and the DMD chip 2 is in contact with the housing 4 under spring pretension.

[0033] In the embodiment of the Fig. 2, the heat dissipation element 9, the circuit board 1, the DMD chip 2, and the interposer 3 are connected to form a pre-assembly unit. For this purpose, the heat dissipation element 9 has, in addition to the first spring arms 14, several pairs of second spring arms 17, with the spring arms 17 of a pair also extending diametrically to each other.

[0034] The free ends of the second spring arms 17 have screw through-holes 20 at their free end regions. Screws (not shown) of a second screw connection protrude through these holes 20, are guided through corresponding through-holes in the circuit board 1 and the interposer 3 and are screwed into threaded holes of a counter-element 18. The counter-element 18, arranged radially outside the DMD chip 2, has radially inwardly projecting support points 19 against which the DMD chip 2 rests with its circumferential edge 5. The screws of the second screw connection not only hold the parts of the pre-assembly unit together, but also hold the heat dissipation block 10, with its end face facing the DMD chip 2, in contact with the DMD chip 2 under spring preload.

Claims

[1] A surface light modulator (SLM) comprising a printed circuit board (1) provided with conductor tracks for contacting a DMD chip (2), wherein the DMD chip (2) is supported under prestress on its side facing the printed circuit board (1) with its peripheral edge (5) on a housing (4) having an opening (6) leaving the area of ​​the DMD chip (2) enclosed by the peripheral edge (5) free, wherein the DMD chip (2) is supported with its other side, optionally via an interposer (3), on one side of the printed circuit board (1), having a heat dissipation element (9) arranged on the side of the printed circuit board (1) opposite the DMD chip (2), and wherein the package comprising the printed circuit board (1), optionally the interposer (3), and the DMD chip (2) is held on the housing (4) by a screw connection between the heat dissipation element (9) and the housing (4), and wherein the circuit board (1) and if necessarythe interposer (3) each have a through-opening (8) through which a heat dissipation block (10) of the heat dissipation element (9) projects, wherein the heat dissipation element (9) is acted upon by a spring force in such a way that the heat dissipation block (10) is held in contact with the DMD chip (2) with its end face facing the DMD chip (2) under spring preload, . characterized by that the heat dissipation element (9), the printed circuit board (1), the DMD chip (2) and optionally the interposer (3) are connected to one another to form a pre-assembly unit, in which the heat dissipation block (10) is held in contact with the DMD chip (2) with its end face facing the DMD chip (2) under spring preload and the pre-assembly unit can be connected to the housing (4). [2] Area light modulator according to claim 1, characterized by that a thermally conductive paste (11) or a thermally conductive foil is arranged between the end face of the heat dissipation block (10) and the DMD chip (2). [3] Area light modulator according to claim 2, characterized by that the thermal paste or thermal foil is made of an elastomer. [4] Area light modulator according to one of the preceding claims, characterized by that the DMD chip (2) has touch contact elements which are held in contact with the conductor tracks of the printed circuit board (1) with a certain force. [5] Area light modulator according to one of the preceding claims, characterized by that the heat dissipation element (9) has a plurality of spring arms (14) projecting parallel to the circuit board (1), the free ends of which are connected to the housing (4) by the screw connection and by means of which the heat dissipation block (10) is held in contact with the DMD chip (2) under prestress. [6] Area light modulator according to one of the preceding claims, characterized bythat the heat dissipation element (9) has a plurality of rigid arms or second spring arms (17) projecting parallel to the circuit board (1), the free ends of which can be connected by a second screw connection to a counter element (18) which, with a plurality of support points (19), applies prestress to the DMD chip (2) against the end face of a stabilization plate (12) facing the DMD chip (2). [7] Area light modulator according to one of the preceding claims 1 to 5, characterized by that the heat dissipation element (9) has a plurality of spring arms (14) projecting parallel to the circuit board (1), the free ends of which are connected to the housing (4) by the screw connection, by means of which the pre-assembly unit is held in contact with second support points (21) of the housing (4) under prestress. [8] Area light modulator according to one of claims 5 to 6, characterized bythat the spring arms (14) and / or the rigid arms or second spring arms (17) are arranged at the end region of the heat dissipation block (10) opposite the DMD chip (2) at a distance from the plane of the printed circuit board (1). [9] Area light modulator according to one of claims 5 to 7, characterized by that the spring arms (14) and / or the rigid arms or second spring arms (17) are formed in one piece with the heat dissipation element (9). [10] Area light modulator according to one of claims 5 to 8, characterized by that the heat dissipation element (9) and, if applicable, the spring arms (14) and / or the rigid arms or second spring arms (17) are made of a metal with good heat conduction. [11] Area light modulator according to claim 9, characterized by that the heat dissipation element (9) and, if applicable, the spring arms (14) and / or second spring arms (17) are made of aluminum or an aluminum alloy. [12] Area light modulator according to one of the preceding claims, characterized by that the heat dissipation element (9) is in contact with the circuit board (1) via an insulating layer. [13] Area light modulator according to claim 12, characterized by that the insulating layer is an insulating foil (16).

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