DMD mounting structure, dmd assembly, and dlp projector including both

Abstract

A DMD mounting structure includes a first clamping element (12) and a second clamping element (14), a plurality of screws (50) and corresponding receiving portions (56), and a force-determining elastic element. The first clamping element (12) and the second clamping element (14) are adapted to receive at least a DMD (16), an interposer (20), and a printed circuit board (22) between them. The screws (50) and the corresponding receiving portions (56) are configured to force the first clamping element and the second clamping element toward each other to securely clamp at least the DMD (16), the interposer (20), and the printed circuit board (22). The force-determining elastic element is a wave spring (48) and is disposed between each screw (50) and each receiving portion (56) to determine the force that forces the first clamping element and the second clamping element toward each other.

Description

Technical Field

[0001] The present invention relates to a mounting structure for a digital micromirror device (commonly referred to as DMD), a DMD assembly, and a digital light processing projector, commonly referred to as a DLP projector, including such a DMD mounting structure and / or such a DMD assembly. Background Technology

[0002] A DMD is a spatial light modulator used in a variety of applications, including DLP projectors. A DMD consists of an array of tiny mirrors, each individually controllable to reflect light in a specific direction. This allows the DMD to adjust the intensity and direction of the light to create an image.

[0003] In a DLP projector, the DMD is the core component that plays a central role in image projection. The DMD receives light from the light source and reflects it onto the projection lens, which then projects the image onto the screen. The quality of the projected image largely depends on the performance and stability of the DMD.

[0004] DMDs are typically manufactured by specialized companies and purchased as separate components by manufacturers of devices employing them. For their intended specific purpose in complex devices such as DLP projectors, the DMD needs to be connected to a printed circuit board with corresponding hardware to power and control it. This is usually accomplished by placing the DMD, a so-called interposer serving as the electronic interface, and the printed circuit board in that order between two clamping elements, which are then forced together by screws. The DMD has a mounting surface area surrounding the mirror array, on which one of the clamping elements acts. This clamping element has an opening for exposing the mirror array.

[0005] While this "clamping together" may sound simple, it is actually a delicate process involving many tasks and meeting several design and structural requirements. For example, the clamping force applied to the DMD via screws must be managed to ensure its proper alignment and stability. Too much force will damage the DMD, while too little force will result in misalignment or instability.

[0006] Besides mechanical stability, thermal management is another major consideration in DMD installation. DMDs generate heat during operation, which, if not properly managed, can affect their performance and lifespan. Therefore, the installation structure needs to include heat sinks or similar thermal management components to dissipate the heat generated by the DMD.

[0007] For optimal results, the heatsink needs to be in contact with the DMD. While theoretically, indirect contact between the heatsink and DMD could be achieved by inserting an adapter made of a material with good thermal conductivity between them, this would only add another component, and direct contact between the heatsink and DMD is preferred.

[0008] To ensure proper direct contact between the heat sink and the DMD, the heat sink typically includes a section called a cooling stud, which has a contact surface that substantially corresponds in shape and size to the so-called thermal interface region provided on the DMD, typically on a side opposite the side with the DMD mirror. To expose this thermal interface region while allowing the DMD to be clamped together with the interposer, the DMD includes an electrical interface region surrounding the thermal interface region. This electrical surface region also serves as the counterpart to the mounting surface region, i.e., the clamping force holding the DMD in place acts on both regions. The interposer has an electrical interface region that substantially corresponds in shape and size to the electrical interface region of the DMD, and an opening exposing the thermal interface region. The printed circuit board also has such an opening, allowing the cooling stud to contact the thermal interface region of the DMD through openings in both the printed circuit board and the interposer.

[0009] By forcing the heatsink with screws toward the DMD, the contact surface of the cooling studs is pressed against the thermal interface area. Similarly, the force applied to the DMD, this time by the cooling studs, must be carefully managed, as too much force can damage the DMD, while too little force can lead to instability and poor thermal contact.

[0010] A particular challenge arises from the fact that the thermal interface region on one side and the electrical interface region and mounting surface region on the other side have different pressure tolerances. This means that the force exerted by the cooling stud contact surface against the thermal interface region and the clamping force acting on the electrical interface region and mounting surface region are different. Typically, the force that should be applied by the cooling stud contact surface to the thermal interface region is only about half the clamping force.

[0011] To at least partially address various issues related to DMD mounting, CN 111679396 A and US 11,265,521B2 both disclose DMD mounting structures employing helical springs positioned along the screw and corresponding components. When the spring stiffness is known, i.e., when the force required to compress (or extend) the spring per unit distance is known, the spring can be used to determine and thus control the clamping force and the force applied to the contact surfaces of the cooling stud.

[0012] However, due to the typically limited space in complex devices employing DMDs, the final assembly obtained by clamping the DMD, interposer, and printed circuit board together using a DMD hump-shaped structure and attaching the heatsink must be very compact. Furthermore, since the heatsink is attached to the DMD mounting structure, and the cooling stud actually passes through the clamping elements, printed circuit board, and interposer before finally reaching the thermal interface region, it needs to be quite long within the known mounting structures, which limits the heatsink's cooling capacity. The thermal resistivity of the cooling stud is proportional to its length divided by its contact surface size. Therefore, since the contact surface is determined by the thermal interface region of the DMD, the shorter the cooling stud, the lower its thermal resistance and the better the cooling effect.

[0013] In summary, mounting a DMD in a device such as a DLP projector involves a delicate balance between mechanical stability and thermal management. The choice of materials and the design of the mounting structure play a central role in achieving this balance, influencing the DMD's performance, reliability, and lifespan, and thus the quality of the projected image. Therefore, improved DMD mounting structures are needed. Summary of the Invention

[0014] The present invention aims to solve the problems mentioned above related to the DMD installation structures and DMD components known to date.

[0015] The problem is solved by the DMD mounting structure according to claim 1, and correspondingly by the DMD assembly according to claim 7. Independent claim 15 relates to a DLP projector comprising the DMD mounting structure and / or DMD assembly according to the invention. Advantageous embodiments are defined in the dependent claims.

[0016] According to the present invention, a DMD mounting structure includes: a first clamping element and a second clamping element, a plurality of screws and corresponding receiving portions, and a force-determining elastic element disposed between each screw and each receiving portion. The first and second clamping elements are adapted to receive at least a DMD, an interposer, and a printed circuit board between them. The screws and corresponding receiving portions are adapted to force the first and second clamping elements toward each other to securely clamp the at least DMD, interposer, and printed circuit board disposed between the clamping elements. The force-determining elastic element is a wave spring adapted to determine the force that forces the first and second clamping elements toward each other.

[0017] Surprisingly, using wave springs instead of the helical springs used to date offers numerous advantages over existing technologies, resulting in a more compact DMD mounting structure and thus facilitating a reduction in the length of the cooling studs, effectively increasing their cooling capacity. Wave springs offer a lower operating height: they can achieve the same force and deflection as helical springs, yet occupy less space axially. The wave profile provides a more consistent force distribution across the spring's surface area; the wave design distributes pressure more evenly, potentially increasing spring life and reliability.

[0018] While wave springs can be formed from various wire types, flat wire is generally preferred. This not only contributes to a compact profile and specific force-deflection characteristics but also positively influences factors such as spring height, load capacity, and deflection characteristics. Compared to round wire, flat wire construction allows for a more consistent and predictable force distribution, but the optimal choice may depend on specific application requirements.

[0019] The preferred flat profile of wave springs makes them easier to center in an assembly. The wider contact area of ​​wave springs provides improved resistance to lateral movement. The waveform pattern can be adjusted to achieve a specific force-deflection curve. Compared to helical springs, wave springs exhibit a less tendency to resonate at certain frequencies and offer improved damping characteristics, which is particularly beneficial in DMD applications, where minimizing vibration is crucial for maintaining image quality. The unique wave profile of these springs helps to absorb and dissipate vibrational energy more effectively. Due to their flatter profile and larger contact area, wave springs made of flat wire generally offer improved thermal conductivity and thus help dissipate heat generated by the DMD during use.

[0020] Wave springs typically provide a more precise and consistent force application over their surface area. This uniform force distribution helps ensure uniform pressure on the DMD, which can contribute to improved alignment stability and potentially enhance the overall optical performance of the device. Furthermore, wave springs and coil springs operate on different mechanical principles: wave springs rely primarily on bending forces, while coil springs act through torsional forces. When a load is applied to a wave spring, its waveform begins to flatten, generating an upward force that allows for axial and radial load transfer. This contributes to more consistent and predictable force application within the DMD mounting structure, thereby improving component stability and reliability. In contrast, coil springs twist upon compression, resulting in not all forces being perfectly aligned with the axis. In some cases, the torsional action during compression can cause the coil spring to buckle.

[0021] The compact nature of wave springs allows for a reduction in the overall size of the DMD mounting structure. This size reduction results in a lighter final component.

[0022] In some cases, wave springs can also offer greater design flexibility. Their unique shape allows for customization of spring characteristics, such as force-deflection curves, by adjusting parameters such as the number of waves, wave height, and material thickness. This adaptability enables fine-tuning of the performance of the mounting structure to meet specific application requirements.

[0023] According to a preferred embodiment, the receiving part is a threaded sleeve or threaded hole disposed on or in one of the first clamping element and the second clamping element. This contributes to the compactness of the DMD mounting structure because a separate element such as a nut is not required. Furthermore, the threaded sleeve can advantageously have a dual function and serve as a centering element for other components.

[0024] According to another preferred embodiment, a wave spring is disposed between the screw head and the side of one of the first and second clamping elements, the clamping element being positioned away from the other clamping element in a bevel configuration. In this way, the wave spring acts as a washer to prevent direct abrasive contact between the screw head and the corresponding clamping element. Although in principle the wave spring could also be disposed, for example, between the first and second clamping elements, the preferred arrangement facilitates assembly because the wave spring can be placed on the corresponding screw, and the screw can then be easily installed to hold the wave spring.

[0025] According to another preferred embodiment, the first clamping element may be a mounting plate having a DMD receiving portion with an opening for exposing the mirror of the DMD and a receiving portion for receiving screws. Around the opening for exposing the mirror, a mounting surface area for receiving the DMD and a groove or recess for centering the DMD may be provided. When the first clamping element is such a mounting plate, the second clamping element may advantageously be a pressure plate having an opening on the side of the DMD opposite its mirror and a centering sleeve for each wave spring.

[0026] According to another preferred embodiment, the second clamping element may further include a plurality of threaded sleeves or threaded holes for receiving mounting screws for attaching the heat sink to the second clamping element. This provides another significant advantage over DMD mounting as known from the two prior art documents described above, which teach that “attachment” screws, i.e., screws for attaching the heat sink, are screwed into “clamping” screws, i.e. screws for clamping the first and second clamping elements; when the clamping screws loosen in this configuration, the contact between the thermal interface area of ​​the DMD and the cooling studs automatically loosens. Furthermore, since the axes of the clamping screws and the corresponding attachment screws are coaxial, the clamping screws are effectively extended, allowing high torque forces to be applied to the first clamping element.

[0027] A DMD assembly according to the present invention includes the above-described DMD mounting structure, a DMD, an interposer, and a printed circuit board, arranged in this order between a first clamping element and a second clamping element.

[0028] According to a preferred embodiment, the DMD assembly further includes a heat sink attached to a second clamping element, the heat sink having a cooling stud that contacts the side of the DMD opposite to its mirror.

[0029] According to another preferred embodiment, the heat sink is a liquid-cooled heat sink.

[0030] Attaching a heatsink can be accomplished using mounting screws. In this case, force-determining elastic elements can be positioned between the head of each mounting screw and the heatsink. These elastic elements can be wave springs or conventional helical springs, because the force from the mounting screws, which is determined by these elastic elements, is typically smaller than the force applied by the clamping screws, as mentioned above, and the length of the spring has no effect on the length of the cooling stud.

[0031] According to another preferred embodiment, the first clamping element is a mounting plate, and at least a first seal, preferably a first seal and a second seal, are disposed on one side of the mounting plate surrounding the DMD, or correspondingly on both sides thereof. Such seals can particularly prevent dust particles from entering the DMD assembly and affecting, for example, a printed circuit board or the DMD itself. The DMD can be adhered to the mounting plate.

[0032] According to another preferred embodiment, the sides of the DMD and the DMD facing the receiving portion, and / or the sides of the interposer and the DMD facing the interposer, and / or the sides of the printed circuit board and the interposer facing the printed circuit board, may be provided with centering protrusions and corresponding grooves / openings, thereby effectively facilitating assembly of components.

[0033] According to another preferred embodiment, an insulating layer is disposed between the second clamping element and the printed circuit board.

[0034] Other advantages and details of the invention will become apparent from the following detailed description of preferred embodiments, taken in conjunction with the accompanying drawings, which include six figures. Attached Figure Description

[0035] Figure 1 A perspective view of a DMD assembly in its installed state is shown according to an embodiment of the present invention.

[0036] Figure 2 It is based on Figure 1 A top view of the DMD component.

[0037] Figure 3 It is along Figure 2 Along the direction shown by the middle arrow iii Figure 2Cross-sectional view of centerline III-III.

[0038] Figure 4 It is based on Figure 1 A partial exploded view of the DMD components.

[0039] Figure 5 This is a perspective view of a heat sink that can be used in another embodiment of the present invention.

[0040] Figure 6 It is based on Figure 5 Another perspective view of the radiator. Detailed Implementation

[0041] exist Figures 1 to 4 The diagram illustrates a DMD assembly 10 according to an embodiment of the present invention. It should be noted that, to avoid overloading the drawings, not all shown elements are typically provided with reference numerals. For example, when many identical screws, through holes, springs, etc., are present, only some are provided with reference numerals.

[0042] Component 10 includes a mounting plate 12 as a first clamping element and a pressure plate 14 as a second clamping element. A DMD 16, a first seal 18, an intermediary sheet 20, and a printed circuit board 22 are disposed between these clamping elements. The first seal 18 surrounds the DMD 16 and has an opening 24, which is substantially complementary in shape and size to the components of the DMD it surrounds.

[0043] Component 10 further includes a heat sink, which is generally indicated by 26. Figures 1 to 4 In the illustrated embodiment, the radiator is liquid-cooled and includes a cooling plate 28, cooling studs 30, and a cooling element 32 attached to the cooling plate and adapted to circulate the cooling liquid entering and exiting the cooling element 32 through through-holes 34, 36. The cooling plate 28 has a dual function, providing not only cooling for the studs 30 and thus thermal contact with the DMD 16, but also multiple through-holes 38 that allow mounting screws 40 to pass through the cooling plate 28 to corresponding threaded sleeves 42 disposed on the pressure plate 14, while simultaneously providing a contact surface for a helical spring 44, which determines the force provided by the screw 40, which presses the helical spring against the cooling plate 28 through its screw head, and thus presses the cooling studs 30 against the DMD 16. In the illustrated embodiment, a helical spring 44 is used, but wave springs may also be used depending on the overall design requirements.

[0044] In addition to the threaded sleeve 42, the pressure plate 14 also includes a centering sleeve 46 for aligning the wave springs 48. The centering sleeve 46 is disposed around a corresponding through-hole, allowing the clamping screw 50 to pass through the pressure plate 14. The surface of the pressure plate 14 surrounding the centering sleeve 46 serves as the contact surface for one end of each wave spring 48, while the head 52 of the clamping screw 50 provides a contact surface for the opposite end of each wave spring 48. So-called shoulder screws 50 are used as clamping screws; their heads 52 eliminate the need for washers, further contributing to a reduced mounting height. The printed circuit board 22 is also provided with corresponding through-holes 54, allowing the screw 50 to pass through corresponding threaded sleeves 56 disposed on the mounting plate 12 for receiving the screw 50.

[0045] In addition to the threaded sleeve 56, the mounting plate 12 includes a receiving portion 58 for receiving and aligning the DMD 16. The receiving portion 58 is provided with an opening 60 for exposing the mirror of the DMD 16. Surrounding the opening 60 in the receiving portion 58 is an mating surface 62, which effectively presses against the mounting surface area surrounding the mirror of the DMD 16. The DMD 16 can be glued to the mounting plate 12, which may make a separate seal redundant.

[0046] Although not shown in the schematic diagram, the DMD16 includes an electrical surface area on its side opposite the mirror, which corresponds to the mounting surface area and surrounds the thermal interface area pressed against the cooling stud 30. The electrical surface area is provided with multiple electrical contacts, with the interposer 20 designed to contact these contacts and connect them to the printed circuit board 22. To ensure proper alignment of the interposer 20 and the DMD16, the DMD is provided with multiple recesses 64, and the interposer 20 is provided with corresponding centering protrusions (not visible in the figure). Similarly, for alignment with the interposer 20, the printed circuit board 22 is provided with multiple openings 66, and the interposer 20 is provided with corresponding centering protrusions 68. In use, the screw 50 is screwed into the threaded sleeve 56, the screw head 52 presses the wave spring 48 against the pressure plate 14, which in turn presses against the mounting plate 12, thereby clamping the components disposed between the mounting plate 12 and the pressure plate 14 together. Since the spring stiffness is known, the force applied to the pressure plate 14, and thus specifically to the electrical surface area and mounting surface area of ​​the DMD 16, can be determined and therefore applied in a controlled manner. In typical applications with a typical DMD, a wave spring with a spring stiffness of approximately 12 to 15 N / mm and a working height of approximately 2 to 4 mm (the length between the screw head 52 and the mating surface on the pressure plate 14) can be used to apply the required force. A typical helical spring used to achieve the same force would have a spring stiffness of approximately 20 to 25 N / mm and a working height of approximately 8 to 10 mm, thus making the assembly thicker and requiring a longer cooling stud.

[0047] The printed circuit board 22 is provided with electronic circuitry 70 and electrical connectors 72, only some of which are provided with reference numerals.

[0048] To allow the cooling stud 30 to pass through to the DMD 16, or more precisely, to its thermal interface region, the pressure plate 14 is provided with an opening 74, the printed circuit board 22 is provided with an opening 76, and the interposer 20 is provided with an opening 78. For example... Figure 3 As may be best shown, the inventive arrangement of using wave spring 48 makes the design of the DMD mounting structure very compact and, in particular, makes the height between mounting plate 12 and pressure plate 14 very low, which in turn allows the cooling stud 30 to be as short as possible, thereby limiting its thermal resistance and improving the cooling of DMD 16.

[0049] In the illustrated embodiment, the DMD assembly 10 further includes a second seal 80 attached to the mounting plate 12 from a side opposite to the receiving portion 58. This seal 80 may have a self-adhesive surface for attachment to the mounting plate 12 and includes an opening 82 for exposing the mirror of the DMD 16. The mounting plate includes a plurality of through holes 84 for mounting the DMD assembly 10 to other components of a device employing the assembly, such as, in particular, a DLP projector.

[0050] Figure 5 and Figure 6 Two different perspective views illustrate a heat sink 86 that can be used in embodiments of the present invention. This heat sink 86 is not liquid-cooled and includes multiple heat exchange plates 88 in contact with the surrounding air. It should be noted that in the exemplary embodiment of the heat sink 86 shown, when such a heat sink 86 should be used instead of... Figure 4 When the heat sink 26 in the assembly shown is installed, the orientation of the opening 90 for mounting screws and the cooling stud 92 must of course be adapted to the position and orientation of the threaded sleeve 42 and the openings 74, 76 and 78.

[0051] List of reference numerals in the attached diagram:

[0052] 10DMD Components

[0053] 12 First clamping element (mounting plate)

[0054] 14 Second clamping element (pressure plate)

[0055] 16DMD

[0056] 18 First seal

[0057] 20 Intermediary Films

[0058] 22 Printed Circuit Boards

[0059] 24 Opening

[0060] 26 Radiators

[0061] 28 Cooling plate

[0062] 30 Cooling Stud

[0063] 32 Cooling elements

[0064] 34 sockets

[0065] 36 sockets

[0066] 38 through holes

[0067] 40 mounting screws

[0068] 42 Threaded sleeve

[0069] 44. Coil spring

[0070] 46 Centering Sleeve

[0071] 48 Wave springs

[0072] 50 clamping screws

[0073] 52 Screw head

[0074] 54 Through Hole

[0075] 56 Threaded Sleeve

[0076] 58 Receiving Department

[0077] 60 opening

[0078] 62 mating surfaces

[0079] 64 Grooves

[0080] 66 Opening

[0081] 68 Centering protrusion

[0082] 70 Electronic Circuits

[0083] 72 Electrical Connectors

[0084] 74 Opening

[0085] 76 Opening

[0086] 78 Opening

[0087] 80 Second seal

[0088] 82 Opening

[0089] 84 through holes

[0090] 86 Radiator

[0091] 88 heat exchange plate

[0092] 90° opening

[0093] 92 Cooling Stud

Claims

1. A DMD mounting structure, comprising: - A first clamping element (12) and a second clamping element (14), the first clamping element and the second clamping element being adapted to receive at least a DMD (16), an interposer (20) and a printed circuit board (22) between them; - Multiple screws (50) and corresponding receiving parts (56) for forcing the first clamping element and the second clamping element toward each other to securely clamp at least the DMD, the interposer and the printed circuit board; - A force-determining elastic element, disposed between each screw and each receiving part, determines the force that forces the first clamping element and the second clamping element toward each other; Its features -The elastic element is a wave spring (48).

2. The DMD mounting structure according to claim 1, wherein The receiving part is a threaded sleeve or threaded hole (56) disposed on one of the first clamping element and the second clamping element or therein.

3. The DMD mounting structure according to claim 1 or 2, wherein The wave spring (48) is disposed between the screw head (52) and the side of one of the first clamping element and the second clamping element, which is in a mountain-shaped state away from the other clamping element.

4. The DMD mounting structure according to claim 1 or 2, wherein The first clamping element is a mounting plate (12), which has -DMD receiving section (58), having an opening (60) for exposing the mirror of the DMD, and - Receiving part (56) for receiving the screw.

5. The DMD mounting structure according to claim 4, wherein, The second clamping element is a pressure plate (14) having an opening (74) for exposing the side of the DMD opposite to its mirror and a centering sleeve (46) for each wave spring.

6. The DMD mounting structure according to claim 1 or 2, wherein, The second clamping element further includes a plurality of threaded sleeves or threaded holes (42) for receiving mounting screws (40) for attaching the heat sink to the second clamping element.

7. A DMD component, characterized in that, include -The DMD mounting structure according to any one of claims 1 to 6, and - A DMD (16), an interposer (20), and a printed circuit board (22) are arranged in this order between the first clamping element and the second clamping element.

8. The DMD component according to claim 7, wherein, It also includes a heat sink (26) attached to the second clamping element, the heat sink (26) having a cooling stud (30) in contact with the side of the DMD opposite to its mirror.

9. The DMD component according to claim 8, wherein, The radiator is a liquid-cooled radiator (26).

10. The DMD component according to claim 8 or 9, wherein, The radiator is attached to the second clamping element by mounting screws (40), and also includes a force-determining elastic element (44) disposed between the head of each mounting screw and the radiator.

11. The DMD component (10) according to claim 10, wherein, It also includes at least a first seal (18), preferably a first seal (18) and a second seal (80), disposed on one side of the first clamping element surrounding the DMD or correspondingly on both sides thereof.

12. The DMD component of claim 11, wherein -The DMD and the side of the DMD facing the receiver, and / or - The sides of the intermediary piece and the DMD facing the intermediary piece, and / or - The side of the printed circuit board and the interposer facing the printed circuit board. It is provided with a centering protrusion (68) and a corresponding groove / opening (64, 66).

13. The DMD component according to claim 7, wherein, The DMD is attached to the mounting plate.

14. The DMD component according to claim 7, wherein, It also includes an insulating layer between the second clamping element and the printed circuit board.

15. A DLP projector, characterized in that, It includes the DMD mounting structure according to any one of claims 1 to 6 and / or the DMD component according to any one of claims 7 to 14.

Images