Light source module

Abstract

The present invention makes it possible to provide a technique for improving cooling efficiency of an electronic cooling module. A light source module 100 comprises: a first laser 117 configured to emit red light; an electronic cooling module 530 that adjusts the temperature of the first laser 117; a first heat sink 560 that dissipates heat from the electronic cooling module 530; and a first holding member 600 that holds the first laser 117 and insulates heat so that heat exhausted from the electronic cooling module 530 does not return to a heat absorption path of the electronic cooling module 530.

Description

Light source module

[0001] The present invention relates to an improved technology for a light source module.

[0002] Light source modules are used in various image display devices. As a conventional technology for such a light source module, for example, there is a technology disclosed in Patent Document 1.

[0003] The technology disclosed in Patent Document 1 constitutes a laser light source unit with a light source module (light source unit) that combines and emits laser light, and an optical system (projection unit) that projects the laser light emitted from the light source module. In image display devices such as color projectors, three-color lasers of red, blue, and green (such as laser diodes) are used, and forced cooling using an electronic cooling module such as a Peltier element is performed based on the light emission characteristics of these lasers depending on temperature. Generally, these lasers are positioned and fixed to a main body by metal holding components.

[0004] Japanese Patent No. 6606633

[0005] However, in the technology disclosed in Patent Document 1, heat exhausted from the electronic cooling module can return to the heat absorption path of the laser and the electronic cooling module through the holding portion, which is disadvantageous for improving the cooling efficiency of the electronic cooling module if left unchanged.

[0006] The present invention has been made to solve the above problem, and an object of the present invention is to provide a technology for improving the cooling efficiency of an electronic cooling module.

[0007] The light source module according to the first aspect includes: a first laser configured to emit red light; an electronic cooling module that adjusts the temperature of the first laser; a first heat sink that dissipates heat from the electronic cooling module; and a first holding member that holds the first laser and provides heat insulation such that heat exhausted from the electronic cooling module does not return to the heat absorption path of the electronic cooling module.

[0008] In a light source module in a second embodiment that may be dependent on the first embodiment, the first holding member is made of a heat-resistant resin to insulate against heat discharged from the electronic cooling module so as not to return to the heat absorption path of the electronic cooling module.

[0009] A third light source module, which may be dependent on the first or second embodiment, further comprises a first heat sink that transfers heat from the first laser to the electronic cooling module, the first holding member also serves as a housing member capable of housing the electronic cooling module and the first heat sink, the opening of the first holding member on the first heat sink side is closed by a sealing plate capable of transferring heat dissipated from the electronic cooling module to the first heat sink, and the space between the first holding member and the sealing plate is moisture-proof sealed.

[0010] A light source module in a fourth embodiment which may depend on the first to third embodiments further comprises: a second laser configured to emit green light; a third laser configured to emit blue light; a second heat sink for dissipating heat from the second and third lasers; a second heat sink for transferring heat from the second and third lasers to the second heat sink; and a second holding member formed of a heat-resistant resin for holding the second and third lasers.

[0011] A light source module in a fifth embodiment, which may be dependent on the fourth embodiment, further comprises a first case for housing the first laser and a second case for housing the second laser and the third laser.

[0012] In a sixth embodiment of the light source module that may be dependent on the fifth embodiment, the second case has a moisture-permeable portion that allows water vapor to pass through.

[0013] In a seventh embodiment of the light source module which may depend on the fifth or sixth embodiment, the first case has a transparent portion that transmits the red light and can seal the inside of the first case, and the transparent portion is arranged to transmit the red light and allow it to enter the second case.

[0014] According to the present invention, a technology is provided that can improve the cooling efficiency of the electronic cooling module of a light source module.

[0015] These are external views and a circuit diagram of an image display device equipped with a light source module according to an embodiment. Figure 1 is a cross-sectional view of the light source module shown. Figure 2 is an enlarged view of part 3. Figure 3 is an enlarged view of part 4. Figure 2 is an enlarged view of part 5.

[0016] Embodiments of the present invention will be described below with reference to the accompanying drawings. The best embodiments described below are provided for ease of understanding the present invention. Therefore, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

[0017] Figure 1 shows an example of the external appearance of the image display device 10, and an example of the internal configuration of the light source unit 100 and the projection unit 300. In the example of Figure 1, the image display device 10 is an in-vehicle projection type display system (in-vehicle projector) mounted on a vehicle (not shown). However, the image display device 10 of the present invention is not limited to an in-vehicle projection type display system mounted on a vehicle (not shown).

[0018] In recent years, there has been a demand for higher brightness in image display devices (in-vehicle projection display systems) to improve visibility. However, in order to make the light source shine brighter, it is necessary to efficiently dissipate the heat generated by the light source, which tends to increase the size of heat sinks and other heat dissipation components. As a result, image display devices may become larger, and it is conceivable that they may no longer be able to be installed in the limited space of vehicles.

[0019] Therefore, in this invention, the light source unit 100 and the projection unit 300 are separated using optical transmission technology via optical fiber cables 220 to construct a separate image display device 10 (in-vehicle projection display system 10). Hereinafter, the light source unit 100 may be referred to as the "light source module 100," and the optical fiber cable 220 may simply be referred to as the "optical fiber 220."

[0020] By separating the light source unit 100 and the projection unit 300, the light source unit 100, which generates a large amount of heat, can be installed in available space on a vehicle or the like, while the projection unit 300, which forms the projected image, can be separated from the heat source and freely installed in an appropriate location, thus facilitating the installation of the image display device 10 on a vehicle.

[0021] On the other hand, after installing the light source unit 100 and the projection unit 300 in an empty space in a vehicle or the like, it is necessary to connect the light source unit 100 and the projection unit 300 with a communication cable 210 and an optical fiber 220. After this work, it is necessary to determine whether the image display device 10 is operating normally, and if an abnormal condition is detected, appropriate measures such as stopping the light output or notifying the abnormality must be taken. However, the amount of light transmitted through the optical fiber 220 can vary greatly depending on the wiring conditions of the optical fiber 220 and the ambient temperature, and under such circumstances, it is not easy to determine normal / abnormal based solely on the light reception intensity of the light receiving unit 324 provided on the projection unit 300 side.

[0022] Therefore, in this embodiment, a light receiving unit 123 is also provided on the light source unit 100 side, and information on the measured light intensity obtained from this light receiving unit 123 and information on the measured light intensity obtained from the light receiving unit 324 on the projection unit side are acquired, and by using each piece of information to perform abnormality determination processing in a predetermined procedure, it is possible to detect abnormalities in the in-vehicle projection display system 10 caused by the wiring condition of the optical fiber 220, ambient temperature, etc.

[0023] The following will provide a detailed explanation with reference to the diagrams.

[0024] As shown in Figure 1, the image display device 10 has a light source unit 100 and a projection unit 300 arranged separately. The light source unit 100 and the projection unit 300 are electrically connected via a communication cable 210, and the light for forming the projected image output by the light source unit 100 is supplied to the projection unit 300 via an optical fiber 220, and the projection unit 300 forms the projected image. The communication cable 210 may be used for transmitting power, control signals, video signals, etc.

[0025] The light source unit 100 includes a control board 102, an integrated circuit device 103 including a microcontroller 110 (MCU 110: see Figure 1) which serves as a first control unit mounted on the control board 102, and a plurality of mirrors 120-122 as optical elements. On the other hand, the projection unit 300 includes a projection port (output port) 323 for projecting (emitting) display light for the image.

[0026] The light source unit 100 includes an MCU 110 as a first control unit, a serializer 112 (parallel / serial converter), a deserializer 114 (parallel / serial converter), an optical element drive unit 116 (LC driver), a plurality of optical elements 117 to 119 with different light colors (here, laser diodes corresponding to R (red), G (green), and B (blue)), a plurality of mirrors 120 to 122, a first light receiving unit 123 (here, a first photodiode PD1 is used) that detects the light intensity of the light for forming projected images of each color output from the light source unit 125, an optical output interface 124, and a power circuit 130 (power supply circuit).

[0027] The MCU110 is an integrated circuit device that combines a processor, which functions as the main CPU (host CPU), with peripheral circuits such as memory.

[0028] The MCU 110 is equipped with a first light intensity measuring unit 111 that measures light intensity based on measured values ​​(pd1(R'' / G'' / B'')) of red (R), green (G), and blue (B) light sent from a first light receiving unit (PD1) 123, and an abnormality determination unit 113.

[0029] The optical element section 125 is composed of multiple optical elements 117-119 with different light-emitting colors, multiple mirrors 120-122, a first light-receiving section (first photodiode PD1) 123, and an optical output interface 124.

[0030] The serializer 112 and the deserializer 114 constitute the first serial interface unit SIF1.

[0031] The projection unit 300 includes a deserializer (serial / parallel converter) 312, a display controller (display control device) 313 as a second control unit, a serializer (parallel / serial converter) 314, an optical input interface 320, an optical modulator (in this case, a DMD (digital mirror device) is used) 322, a second light receiving unit (in this case, a second photodiode PD2 is used) 324 that detects the light intensity of each color of light for forming the projection image sent via the optical fiber 220, and a power circuit (power supply circuit) 325.

[0032] The display controller 313 is a dedicated integrated circuit device equipped with a sub-CPU (not shown) that performs display control in place of the MCU 110.

[0033] The display controller 313 is equipped with a second light intensity measuring unit 315 that measures light intensity based on measured values ​​(pd2(R'' / G'' / B'')) of R, G, and B colored light sent from the second light receiving unit (PD2) 324.

[0034] The deserializer 312 and serializer 314 constitute the second serial interface unit SIF2.

[0035] The optical modulator 322 includes a main body 319 in which an optical modulator element is built in, an input terminal 321 of the optical modulator 322 to which video bitstream data VBSD supplied from the display controller 313 is input, and a projection port 323 for projecting display light of the image.

[0036] The optical input interface 320 receives the light for projection image formation transmitted from the light source unit 100 via the optical fiber 220, and supplies the received light (light of each color, R, G, and B) to the main unit 319 of the optical modulator 322.

[0037] Next, we will explain the content of the communication of video signals and control signals via the first serial interface unit SIF1 and the second serial interface unit SIF2.

[0038] The serial communication signals transmitted and received between the first serial interface unit SIF1 and the second serial interface unit SIF2 include, for example, a serial video signal (LVDS VideoS) transmitted from the light source unit 100 to the projection unit 300 using the LVDS (Low Voltage Differential Signal) transmission method, an illumination enable signal (LDE: specifically, LEDR / G / BLD Enable for each color) transmitted from the light source unit 100 to the projection unit 300 which permits the illumination of the optical elements 117 to 119, and various communication signals (CommunicationS1, CommunicationS2).

[0039] Next, an example of various communication signals will be described. For example, a vehicle-side controller 90 mounted on a vehicle (not shown) can send various request commands C1 based on user settings to the MCU 110 of the light source unit 100.

[0040] Possible request commands include, for example, commands to change the display brightness, color balance, image size, image position, projection distortion correction, and turning the display on / off.

[0041] The MCU 110 sends the received request command as a communication signal C2 to the serializer 112, the serializer 112 converts the received communication signal C2 from parallel to serial to generate a communication signal Communication S1, and transmits this communication signal Communication S1 to the projection unit 300 via the communication cable 210. The deserializer 312 of the projection unit 300 converts the received communication signal Communication S1 from serial to parallel to generate a communication signal C3, and sends this communication signal C3 to the display controller (second control unit) 313.

[0042] The display controller 313 executes processing in response to various requests from the MCU 110 of the light source unit 100, and generates a signal C4 indicating the result of executing the processing (for example, a signal indicating that the processing has been successfully completed, or a signal indicating a parameter value obtained as a result of the processing) and sends the signal C4 to the serializer 314. The serializer 314 performs parallel-to-serial conversion on the communication signal C4 to generate the communication signal CommunicationS2, and transmits this communication signal CommunicationS2 to the light source unit 100 via the communication cable 210. The deserializer 114 of the light source unit 100 performs serial-to-parallel conversion on the received communication signal CommunicationS2 to generate the communication signal C5, and sends the communication signal C5 to the MCU 110.

[0043] In this way, the MCU 110 and the display controller 313 can transmit and receive various signals via the first and second serial interface units SF1 and SF2.

[0044] Next, the transmission of video signals will be described. The vehicle-side controller 90 transmits the video signal VideoS to the serializer 112 of the light source unit 100. The serializer 112 generates an LDVS-format video signal LDVS VideoS based on the received video signal VideoS, and transmits the generated signal to the projection unit 300 via the communication cable 210. The deserializer 312 of the projection unit 300 converts the received LDVS-format video signal LDVS VideoS into a parallel-format video digital signal VD, and sends the video digital signal VD to the display controller 313.

[0045] Next, the flow of signals related to abnormality determination processing will be described. The display controller 313 can transmit the actual measurement value (pd2) obtained by the second light intensity measurement unit 315 to the light source unit 100 as the light intensity information LI.

[0046] The light intensity information LI sent from the display controller 313 is subjected to parallel-to-serial conversion by the serializer 314, and is transmitted to the light source unit 100 as serial-format light intensity information LI (LightIntesity).

[0047] The deserializer 114 of the light source unit 100 performs serial / parallel conversion on the transmitted serial-format light intensity information LI, transmits the converted information as a communication signal C5 to the MCU 110 (more specifically, to the abnormality determination unit 113), and in parallel therewith, supplies the light intensity information LI to the optical element driving unit 116.

[0048] The abnormality determination unit 113 that has received the light intensity information LI executes predetermined processing using the actually measured value (pd2) at the second light receiving unit 324 (PD2) of the projection unit 300, generates a light source drive value control signal PCR and sends the same to the optical element driving unit 116 as necessary, and appropriately controls the light emission intensity of the optical elements 117 to 119 for each color.

[0049] Furthermore, the optical element driving unit 116 finely adjusts the light emission intensity of the optical elements 117 to 119 for each color such that variation of the actually measured value (pd2) at the second light receiving unit (PD2) within a predetermined period in the received light intensity information LI falls within a predetermined level. Accordingly, APC (Automatic Power Control) that stabilizes the light output of the plurality of optical elements 117 to 119 having different emission colors is implemented.

[0050] Furthermore, power PS is supplied from the vehicle-side controller 90 to the power circuit 130 of the light source unit 100. The power circuit 130 supplies power voltage to the power circuit 325 of the projection unit 300 via the communication cable 210. The power circuit 325 supplies power voltage to each unit in the projection unit 300.

[0051] As described above, each of the optical elements 117 to 119 is constituted by a laser diode (also referred to as a laser). Hereinafter, the optical element 117 configured to emit red light (R) may be rephrased as a "first laser 117", the optical element 118 configured to emit green light (G) may be rephrased as a "second laser 118", and the optical element 119 configured to emit blue light (B) may be rephrased as a "third laser 119". The light emission directions of all the lasers 117 to 119 are the same.

[0052] Furthermore, among the multiple mirrors 120 to 122, the mirror 120 that reflects the red light (R) emitted from the first laser 117 is sometimes referred to as the "first mirror 120," the mirror 121 that reflects the green light (G) emitted from the second laser 118 is sometimes referred to as the "second mirror 121," and the mirror 122 that reflects the blue light (B) emitted from the third laser 119 is sometimes referred to as the "third mirror 122."

[0053] Next, the housing structure and cooling structure for the multiple lasers 117-119 will be described.

[0054] As shown in Figure 2, the second mirror 121 reflects the green light emitted from the second laser 118. This second mirror 121 is positioned on the optical path of the green light incident from the second laser 118 and is tilted with respect to the incident direction D1 of the green light.

[0055] The third mirror 122 transmits the green light emitted from the second laser 118 and reflected by the second mirror 121, and reflects the blue light emitted from the third laser 119. This third mirror 122 is positioned in the optical path of the blue light incident from the third laser 119 and is tilted with respect to the incident direction D2 of the blue light.

[0056] The first mirror 120 transmits the green light emitted from the second laser 118 and the blue light emitted from the third laser 119, while reflecting the red light emitted from the first laser 117. In other words, the first mirror 120 is a dichroic mirror that combines green light, blue light, and red light. The first mirror 120 may be referred to as the "dichroic mirror 120" as appropriate. This dichroic mirror 120 is positioned in the optical path of the red light incident from the first laser 117, is tilted with respect to the incident direction D3 of the red light, and faces the light-receiving surface 124a of the optical output interface 124.

[0057] All mirrors 120-122 and the optical output interface 124 are located on the same optical axis (coordinate line). The second mirror 121 and the third mirror 122 are tilted in the same direction as the first mirror 120. Therefore, the optical output interface 124 can receive light emitted from each laser 117-119.

[0058] Here, the direction R1 in which the red light emitted from the first laser 117 propagates after being reflected by the first mirror 120 (dichroic mirror 120) is called the "first direction R1". The direction R2 opposite to this first direction R1 is called the "second direction R2".

[0059] The second mirror 121, which reflects green light, the third mirror 122, which reflects blue light, and the first mirror 120, which reflects red light, are arranged in this order in the first direction R1, that is, toward the light-receiving surface 124a of the optical output interface 124. Correspondingly, the second laser 118, which emits green light, the third laser 119, which emits blue light, and the first laser 117, which emits red light, are also arranged in this order in the first direction R1.

[0060] Each laser 117-119, each mirror 120-122, and the optical output interface 124 are housed in a case 400. This case 400 consists of a first case 410 that houses only the first laser 117, and a second case 420 that houses the second and third lasers 118 and 119. The first case 410 is housed in the second case 420. The second case 420 further houses all the mirrors 120-122 and the optical output interface 124. The internal space 421 (second storage space 421) of this second case 420 is dustproof and sealed.

[0061] Generally, the first laser 117 generates more heat than the second and third lasers 118 and 119. For this reason, the temperature of the first laser 117 is controlled by an electronic cooling module 530. This electronic cooling module 530 is preferably composed of a Peltier element 531 (Peltier module 531), which is small and lightweight and allows for easy temperature control of small components such as lasers.

[0062] As the temperature of the first laser 117 is adjusted, if the part of the first laser 117 that should be cooled is exposed to highly humid air, condensation may occur, potentially hindering the normal operation of the first laser 117. In particular, water vapor molecules are smaller than dust particles. To address this, the internal space 411 (first storage space 411) of the first case 410 is moisture-proof sealed. Moisture-proof sealing ensures higher airtightness (sealing) compared to dustproof sealing. Dry air is trapped in the moisture-proof sealed first storage space 411.

[0063] The first storage space 411 is sealed to ensure high airtightness. Moreover, the first case 410 is extremely compact because it only needs to house the first laser 117. Therefore, the volume Vm of the first storage space 411 (moisture-proof space 411) that is sealed to prevent moisture can be kept to a minimum. This is extremely advantageous when applying moisture-proof sealing to the first storage space 411.

[0064] As shown in Figure 1, the control board 102 and the integrated circuit device 103 are provided in a dustproof and sealed manner on the side of the case 400, but they may also be housed in the second storage space 421 of the second case 420.

[0065] Next, we will explain the configuration of Case 400 in detail.

[0066] First, the second case 420 will be described. As shown in Figure 2, the second case 420 is a rectangular box and is configured as a dustproof sealed structure by a frame-shaped case body 422 that penetrates from top to bottom, a flat bottom plate 423 (first plate 423) that closes one opening of the case body 422, and a flat top plate 424 (second plate 424) that closes the other opening of the case body 422. An optical output interface 124 is attached to the side of the case body 422.

[0067] The top plate 424 (base material 424) of the second case 420 has a first heat sink 510 and a second heat sink 520 attached to it. The mounting structure of the first heat sink 510 and the second heat sink 520 will be described later (see Figures 4 and 5).

[0068] A portion of the first heat sink 510 protrudes from the top plate 424 into the first storage space 411, and the first laser 117 is mounted in close contact with it. On the side of the first heat sink 510 opposite to the first laser 117, an electronic cooling module 530 and a sealing plate 540 are stacked and fixed in that order. One end face 541 of the sealing plate 540 is a flat exposed surface exposed from the top plate 424. At least one of the first heat sink 510, the electronic cooling module 530, and the sealing plate 540 is moisture-proof sealed to the top plate 424. An example of this moisture-proof sealing configuration is a sealing structure using a sealing member (not shown) such as a highly airtight adhesive or gasket.

[0069] The second heat sink 520 is a flat plate-shaped member. Parts 521, 521 (protruding portions 521, 521) of this second heat sink 520 protrude from the top plate 424 into the second storage space 421, and the second and third lasers 118, 119 are individually and closely arranged on these protruding portions. Of the second heat sink 520, the side 522 (one end surface 522) opposite to the second and third lasers 118, 119 is a flat exposed surface exposed from the top plate 424.

[0070] Thus, all lasers 117 to 119 are arranged in a single line on the inner surface of the top plate 424 (the surface facing the second storage space 421).

[0071] Furthermore, the second case 420 has a moisture-permeable section 550 that allows water vapor generated in the second storage space 421 to pass through while preventing moisture from passing through. This moisture-permeable section 550 combines waterproofness to suppress the intrusion of moisture from the outside with moisture permeability to allow moisture from the second storage space 421 to pass through, and is made of, for example, a moisture-permeable waterproof sheet. The water vapor in the second storage space 421 is released to the outside through the moisture-permeable section 550.

[0072] Since water vapor in the second storage space 421 tends to rise, it is preferable to place the moisture-permeable section 550 on the upper end of the second case 420, for example, on the top plate 424, in order to improve the moisture permeability of the moisture-permeable section 550. Furthermore, in order to suppress the intrusion of moisture from the outside into the second storage space 421 through the moisture-permeable section 550, it is preferable to place the moisture-permeable section 550 at the upper end of the second case 420 and below the first heat sink 560, which will be described later.

[0073] Furthermore, the light source module 100 includes a first heat sink 560 for dissipating heat from the first laser 117, a second heat sink 570 for dissipating heat from the second laser 118 and the third laser 119, and an air cooling fan 580 for dissipating heat from the first and second heat sinks 560 and 570 into the atmosphere.

[0074] The first heat sink 560 and the second heat sink 570 are arranged along the surface of the top plate 424 with a gap Cr between them and are attached to the second case 420. Because there is a gap Cr between the first heat sink 560 and the second heat sink 570, an air layer exists in this gap Cr. This air layer helps to minimize heat transfer between the first and second heat sinks 560 and 570.

[0075] The first heat sink 560 is positioned to transfer heat across the entire surface of the sealing plate 540. Therefore, heat from the electronic cooling module 530 can be dissipated to the first heat sink 560. The second heat sink 570 is positioned to transfer heat across the entire surface of the second heat sink plate 520. Therefore, heat from the second laser 118 and the third laser 119 can be dissipated to the second heat sink 570. The first and second heat sinks 560 and 570 are composed of, for example, plate fin heat sinks, pin fin heat sinks, and corrugated fin heat sinks.

[0076] An air intake port 572 is provided on the end face 571 of the second heat sink 570 that is opposite to the first heat sink 560. A dust filter 573, such as a wire mesh, is provided in this air intake port 572.

[0077] The cooling fan 580 is installed on the end face 561 of the first heatsink 560, opposite to the second heatsink 570, and draws in outside air Ar (air Ar) taken in from the intake port 572 so that it flows through the second heatsink 570 and then the first heatsink 560.

[0078] The outside air Ar (air Ar) drawn in by the cooling fan 580 enters the second heatsink 570 through the intake port 572 via the dust filter 573. The heat generated by the second and third lasers 118 and 119 is transferred from the second heat sink 520 to the second heatsink 570 and dissipated by heat exchange with the air Ar. The air Ar that has passed through the second heatsink 570 enters the first heatsink 560.

[0079] The heat generated by the first laser 117 is transferred from the first heat sink 510 to the electronic cooling module 530 and dissipated thereafter. From the electronic cooling module 530, the heat is then transferred through the sealing plate 540 to the first heat sink 560, where it is further dissipated through heat exchange with the air Ar. The air Ar that has passed through the first heat sink 560 is then dissipated into the atmosphere by the cooling fan 580.

[0080] Next, the first case 410 will be described. As shown in Figure 3, it is preferable for the first case 410 to be housed in the second case 420, which is equipped with the first laser 117, in order to miniaturize and integrate the case 400. For this purpose, the first case 410 is configured to cover the first laser 117, which is located on the top plate 424 of the second case 420, by sealing it to prevent moisture buildup.

[0081] More specifically, the first case 410 is a rectangular box and is integrally attached to the top plate 424 of the second case 420. In other words, only the top end 412 of the first case 410 is open. This open top end 412 is sealed and closed by the top plate 424 to prevent moisture buildup. One example of this moisture-proof sealing configuration is a sealing structure using a sealing member (not shown) such as a highly airtight adhesive or gasket. The bottom plate 413 of the first case 410 is a flat portion that faces the bottom plate 423 of the second case 420 and the reflective surface 120a of the first mirror 120.

[0082] The first case 410 is equipped with a transmissive section 590 to allow red light emitted from the first laser 117, which is housed in the first storage space 411, to pass through the first case 410 to the first mirror 120. This transmissive section 590 is arranged to allow red light emitted from the first laser 117 to pass through the first case 410 and enter the second case 420 (second storage space 421). More specifically, this transmissive section 590 is a flat plate-shaped member such as a transparent glass plate provided on the bottom plate 413 of the first case 410, and is moisture-proof sealed to the first case 410. An example of this moisture-proof sealing configuration is a sealing structure using a sealing member (not shown) such as a highly airtight adhesive or gasket. As is clear from the above description, the entire first case 410 is moisture-proof sealed.

[0083] The first mirror 120 is positioned on the optical path of the red light incident from the first laser 117 after passing through the transmission section 590, and is inclined with respect to the incident direction D3 of the red light. The transmission surface 591 of the transmission section 590 is a flat surface facing the reflective surface 120a of the first mirror 120. With respect to the reflective surface 120a of the first mirror 120, the transmission surface 591 of the transmission section 590 is inclined such that the end 592 in the first direction R1 is further away than the end 593 in the second direction R2. In other words, with respect to the reflective surface 120a of the first mirror 120, the transmission surface 591 of the transmission section 590 opens up towards the light-receiving surface 124a of the optical output interface 124 (towards the first direction R1). The opening angle of the transmission surface 591 of the transmission section 590 with respect to the reflective surface 120a of the first mirror 120 is θ.

[0084] Next, the holding structure for holding the first laser 117 to the top plate 424 (base material 424) will be described. As shown in Figure 4, the first laser 117 is held to the top plate 424 by a first holding member 600. This first holding member 600 consists of a cylindrical body 601 and a flange 602 formed at one end of the body 601. The body 601 is fitted and attached to the top plate 424. The space between the body 601 and the top plate 424 is sealed to prevent moisture buildup.

[0085] The first laser 117 has a laser-side flange 117a that is superimposed on the end face of the flange 602 (retaining-side flange 602) of the first retaining member 600. The first laser 117 is attached to the first retaining member 600 by superimposing the laser-side flange 117a on the retaining-side flange 602 and fixing it with screws 603. The space between the retaining-side flange 602 and the laser-side flange 117a is sealed to prevent moisture buildup.

[0086] The opening 604 on the first heat sink 560 side of the first retaining member 600 is closed by a sealing plate 540 that can transfer heat dissipated from the electronic cooling module 530 to the first heat sink 560. The space between the first retaining member 600 and the sealing plate 540 is moisture-proofed.

[0087] An example of a moisture-proof sealing configuration between the main body 601 and the top plate 424, between the flanges 117a and 602, and between the first retaining member 600 and the sealing plate 540 is a sealing structure using a sealing member (not shown) such as a highly airtight adhesive or gasket.

[0088] The first retaining member 600 also serves as a housing member capable of housing the electronic cooling module 530 and the first heat sink 510. In other words, the electronic cooling module 530 and the first heat sink 510 are arranged in a space 605 (internal space 605) surrounded by the first retaining member 600 and the sealing plate 540. Furthermore, the first retaining member 600 is housed in the first case 410 together with the first laser 117.

[0089] Furthermore, the first retaining member 600 is made of a heat-resistant resin, which insulates it so that the heat dissipated from the electronic cooling module 530 does not return to the heat absorption path of the electronic cooling module 530. It is preferable to use polyphenylene sulfide resin (PPS resin) as the heat-resistant resin that constitutes the first retaining member 600. PPS resin has a relatively low thermal conductivity among resin materials. In other words, PPS resin has a high heat insulation effect. Moreover, PPS resin has excellent electrical insulation properties.

[0090] By constructing the first holding member 600 from a heat-resistant resin with low thermal conductivity (high heat insulation effect), the heat dissipated from the electronic cooling module 530 can be insulated so that it does not travel through the first holding member 600 and return to the heat absorption path of the electronic cooling module 530. Therefore, the heat dissipated from the electronic cooling module 530 can be efficiently transferred to the first heat sink 560 through the sealing plate 540, thereby increasing the cooling efficiency of the electronic cooling module 530.

[0091] Next, a holding structure for holding the second laser 118 and the third laser 119 to the top plate 424 (base material 424) will be described. As shown in Figure 5, the second laser 118 and the third laser 119 are held to the top plate 424 by the second holding member 610.

[0092] The second retaining member 610 is composed of a flat substrate 611, two cylindrical bodies 612, 612 extending from the substrate 611 toward the second laser 118 and the third laser 119, and two flanges 613, 613 formed at one end of the bodies 612, 612. The substrate 611 and the two bodies 612, 612 are fitted and attached to the top plate 424 (for example, fixed by screws 614). The space between the substrate 611 and the two bodies 612, 612 and the top plate 424 is dustproofed.

[0093] The second laser 118 and the third laser 119 have laser-side flanges 118a and 119a that are superimposed on the end faces of the flanges 613, 613 (retaining-side flanges 613, 613) of the second retaining member 610. The second laser 118 and the third laser 119 are attached to the second retaining member 610 by superimposing the laser-side flanges 118a and 119a onto the retaining-side flanges 613, 613 and fixing them with screws 615. The space between the retaining-side flanges 613, 613 and the laser-side flanges 118a and 119a is dustproofed. The space between the substrate 611 of the second retaining member 610 and the second heat sink 520 is also dustproofed.

[0094] An example of a dustproof sealing configuration between the retaining flanges 613, 613 and the laser-side flanges 118a, 119a, between the substrate 611 of the second retaining member 610 and the second heat sink 520, and between the substrate 611 of the second retaining member 610 and the top plate 424 is a sealing structure using sealing members (not shown) such as highly airtight adhesives or gaskets.

[0095] Furthermore, the second holding member 610 is made of a heat-resistant resin to insulate against heat dissipated from the second heat sink 520, preventing it from returning to the second laser 118 and / or the third laser 119. It is preferable to use polyphenylene sulfide resin (PPS resin) as the heat-resistant resin for the second holding member 610, similar to the first holding member 600.

[0096] By constructing the second holding member 610 from a heat-resistant resin with low thermal conductivity (high heat insulation effect), it is possible to insulate it so that the heat dissipated from the second heat sink 520 does not travel through the second holding member 610 and return to the second laser 118 and / or the third laser 119. Therefore, the heat dissipated from the second heat sink 520 can be efficiently transferred to the second heat sink 570, thereby increasing the heat transfer efficiency of the second heat sink 520.

[0097] As shown in Figure 5, the top plate 424 (base material 424) is provided with a plurality of support pins 620 that support the first heat sink 560 and the second heat sink 570.

[0098] To summarize the above explanation, it is as follows:

[0099] As shown in Figure 4, the light source module 100 includes a first laser 117 configured to emit red light, an electronic cooling module 530 that adjusts the temperature of the first laser 117, a first heat sink 560 that dissipates heat from the electronic cooling module 530, and a first holding member 600 that holds the first laser 117 and insulates it so that the heat dissipated from the electronic cooling module 530 does not return to the heat absorption path of the electronic cooling module 530.

[0100] The first laser 117, which emits red light, requires strict temperature control, necessitating cooling by the electronic cooling module 530. In contrast, the first holding member 600, which holds the first laser 117, insulates the electronic cooling module 530 so that the heat dissipated from the electronic cooling module 530 does not return to the heat absorption path of the electronic cooling module 530 through the first holding member 600, thereby increasing the cooling efficiency of the electronic cooling module 530. In other words, the first holding member 600 reduces heat dissipation outside the heat dissipation path, thus minimizing the thermal impact on the first laser 117.

[0101] As shown in Figure 4, the first holding member 600 is further made of a heat-resistant resin to insulate against heat dissipated from the electronic cooling module 530 and prevent it from returning to the heat absorption path of the electronic cooling module 530.

[0102] In this way, by simply constructing the first holding member 600 using a heat-resistant resin, it is possible to insulate the heat dissipated from the electronic cooling module 530 so that it does not return to the heat absorption path of the electronic cooling module 530 through the first holding member 600.

[0103] As shown in Figure 4, the light source module 100 further includes a first heat sink 510 that transfers heat from the first laser 117 to the electronic cooling module 530. The first holding member 600 also serves as a housing member capable of housing the electronic cooling module 530 and the first heat sink 510. The opening 604 of the first holding member 600 on the first heat sink 560 side is closed by a sealing plate 540 that can transfer heat dissipated from the electronic cooling module 530 to the first heat sink 560. The space between the first holding member 600 and the sealing plate 540 is moisture-proof sealed.

[0104] In this way, by sealing the device to prevent moisture buildup, a high degree of airtightness (sealing) can be ensured inside the first holding member 600 that houses the electronic cooling module 530.

[0105] As shown in Figure 5, the light source module 100 further comprises a second laser 118 configured to emit green light, a third laser 119 configured to emit blue light, a second heat sink 570 for dissipating heat from the second laser 118 and the third laser 119, a second heat sink 520 for transferring heat from the second laser 118 and the third laser 119 to the second heat sink 570, and a second holding member 610 made of heat-resistant resin for holding the second laser 118 and the third laser 119.

[0106] The second holding member 610, which holds the second laser 118 and the third laser 119, is made of a heat-resistant resin and has low thermal conductivity, thus providing an insulating effect. Therefore, the second holding member 610 can insulate against heat returning from the second heat sink 520 to the second laser 118 and the third laser 119, thereby reducing heat dissipation outside the heat dissipation path. This improves the cooling efficiency of the second heat sink 570. Moreover, the first laser 117, which emits red light, is mounted on the same base material 424 (top plate 424) as the second laser 118 and the third laser 119. This first laser 117 requires strict temperature control, such as cooling by the electronic cooling module 530. In contrast, the second holding member 610 reduces heat dissipation outside the heat dissipation path, thus minimizing the thermal impact on the first laser 117.

[0107] As shown in Figure 2, the light source module 100 further comprises a first case 410 for housing the first laser 117, and a second case 420 for housing the second laser 118 and the third laser 119.

[0108] Only the first laser 117, which is forcibly cooled by the electronic cooling module 530, is housed in the first case 410. The first case 410 is compact because it houses only the first laser 117, separately from the second laser 118 and the third laser 119. The volume Vm of the moisture-proof space 411 (first storage space 411) that is sealed to prevent moisture is kept to a minimum, making it easy to prevent moisture. Because the volume Vm of the moisture-proof space 411 is small, the force applied to the sealing member due to internal pressure fluctuations caused by temperature changes is small, and the amount of water vapor remaining in the moisture-proof space 411 can be reduced.

[0109] As shown in Figure 2, the second case 420 further has a moisture-permeable section 550 that allows water vapor to pass through.

[0110] The water vapor generated in the internal space 421 (second storage space 421) of the second case 420 can be released to the outside through the moisture permeable section 550. The amount of water vapor remaining in the second storage space 421 can be reduced.

[0111] As shown in Figure 2, the first case 410 further has a transparent portion 590 that transmits red light and can seal the inside of the first case 410 (first storage space 411). This transparent portion 590 is arranged so that red light can be transmitted and incident into the inside of the second case 420 (second storage space 421).

[0112] The first case 410 is sealed by a transmissive section 590 that transmits red light. Therefore, the interior 411 (moisture-proof space 411, first storage space 411) of the first case 410 can be made dustproof and moisture-proof. Despite the moisture-proof sealing configuration of the first case 410, the red light emitted from the first laser 117 housed in the interior 411 of the first case 410 can be efficiently incident on the reflective surface 120a of the mirror 120 (first mirror 120) located inside the second case 420.

[0113] As shown in Figure 3, the second case 420 further includes a dichroic mirror 120 (first mirror 120) that combines green light, blue light, and the aforementioned red light. This dichroic mirror 120 is positioned on the optical path of the red light incident from the transmissive section 590 and is inclined with respect to the incident direction D3 of the red light. The direction R1 in which the red light is reflected by the dichroic mirror 120 and propagates is defined as the first direction R1. The direction R2 opposite to the first direction R1 is defined as the second direction R2. With respect to the dichroic mirror 120, the transmissive section 590 is inclined such that the end 592 in the first direction R1 is further away from the end 593 in the second direction R2.

[0114] Therefore, by simply tilting the transmissive section 590 relative to the dichroic mirror 120, stray light due to the reflection of red light by the dichroic mirror 120 can be prevented as much as possible, and as a result, only light from the normal optical path can be incident on the optical output interface 124 as much as possible.

[0115] As shown in Figure 2, the light source module 100 further includes a first heat sink 560 that dissipates heat from the electronic cooling module 530, and a second heat sink 570 that dissipates heat from the second laser 118 and the third laser 119. The first heat sink 560 and the second heat sink 570 are arranged with an air gap Cr between them.

[0116] Since there is an air gap Cr between the first heat sink 560 and the second heat sink 570, heat transfer between them can be prevented, and as a result, each laser 117-119 can be cooled efficiently.

[0117] As shown in Figure 2, the light source module 100 also has an air cooling fan 580 that draws in air Ar so that it flows over the second heat sink 570 and then the first heat sink 560. This air cooling fan 580 is provided on the end face 561 of the first heat sink 560 that is opposite to the second heat sink 570.

[0118] By using the cooling fan 580 to circulate air Ar over the first and second heat sinks 560 and 570, each laser 117 to 119 can be forcibly and efficiently cooled. In particular, the relatively large amount of heat generated from the first laser 117 can be forcibly and efficiently cooled by the electronic cooling module 530, the first heat sink 560, and the cooling fan 580. Moreover, the second and third lasers 118 and 119, which generate less heat, can be air-cooled first by the second heat sink 570 and the cooling fan 580, and then the first laser 117, which generates more heat, can be air-cooled by the first heat sink 560 and the cooling fan 580. As a result, all lasers 117 to 119 can be cooled even more efficiently.

[0119] Furthermore, the present invention is not limited to the embodiments, provided that it achieves the functions and effects of the present invention.

[0120] The light source module 100 of the present invention is suitable for use in projection-type display systems mounted on vehicles.

[0121] 10 Image display device 100 Light source module 117 First laser 118 Second laser 119 Third laser 410 First case 411 Internal space of the first case (first storage space, moisture-proof space) 420 Second case 421 Internal space of the second case (second storage space) 510 First heat sink 520 Second heat sink 530 Electronic cooling module 540 Sealing plate 550 Moisture-permeable section 560 First heat sink 570 Second heat sink 590 Transparent section 600 First retaining member 604 Opening 610 Second retaining member

Claims

1. A light source module comprising: a first laser configured to emit red light; an electronic cooling module for adjusting the temperature of the first laser; a first heat sink for dissipating heat from the electronic cooling module; and a first holding member for holding the first laser and insulating it so that the heat dissipated from the electronic cooling module does not return to the heat absorption path of the electronic cooling module.

2. The light source module according to claim 1, wherein the first holding member is made of a heat-resistant resin to insulate against heat discharged from the electronic cooling module so that it does not return to the heat absorption path of the electronic cooling module.

3. The light source module according to claim 1, further comprising a first heat sink plate that transmits heat from the first laser to the electronic cooling module, wherein the first holding member also serves as a housing member capable of housing the electronic cooling module and the first heat sink plate, the opening of the first holding member on the first heat sink side is closed by a sealing plate capable of transmitting heat dissipated from the electronic cooling module to the first heat sink, and the space between the first holding member and the sealing plate is moisture-proof sealed.

4. The light source module according to claim 1, further comprising: a second laser configured to emit green light; a third laser configured to emit blue light; a second heat sink for dissipating heat from the second and third lasers; a second heat sink for transferring heat from the second and third lasers to the second heat sink; and a second holding member formed of a heat-resistant resin for holding the second and third lasers.

5. The light source module according to claim 4, further comprising a first case for housing the first laser and a second case for housing the second laser and the third laser.

6. The light source module according to claim 5, wherein the second case has a moisture-permeable portion that allows water vapor to pass through.

7. The light source module according to claim 5, wherein the first case has a transparent portion that transmits the red light and can seal the inside of the first case, and the transparent portion is arranged to transmit the red light and allow it to enter the second case.

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