Image projection device and vehicle lamp

Abstract

The present invention provides an image projection device and a vehicle lamp, which can achieve miniaturization and light weight while suppressing the temperature rise of a digital micromirror device. An image projection device projects an image by reflecting light from a digital micromirror device (102) having a plurality of tiny reflectors, wherein the image projection device comprises: a reflector mounting substrate (101a) on which the digital micromirror device (102) is mounted; a power supply mounting substrate (101b) which is formed separately from the reflector mounting substrate (101a); a flexible cable (108) which electrically connects the reflector mounting substrate (101a) and the power supply mounting substrate (101b); and a reflector power supply unit (109) which supplies power to the digital micromirror device (102) via the flexible cable (108) is mounted on the power supply mounting substrate (101b).

Description

Technical Field

[0001] The present invention relates to an image projection device and a vehicle lamp, and in particular to an image projection device and a vehicle lamp that project an image by reflecting light using a digital micromirror device having a plurality of micro-mirrors. Background Art

[0002] In recent years, with the development of driving assistance and autonomous driving technologies, there has been a growing demand for communicating vehicle action plans or information to the outside of the vehicle. As a method for presenting information to the outside of a vehicle, a method has been proposed in which an image projection device is mounted on a vehicle lamp and projects an image onto the road surface, for example (see, for example, Patent Document 1). In the image projection device and vehicle lamp described in Patent Document 1, the image is projected by reflecting light from a digital micromirror device (DMD) equipped with a plurality of tiny mirrors.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-055519

[0006] Figure 6 This is a schematic diagram showing the structure of an image projection device for a conventional vehicle lamp. The image projection device includes a circuit board 1, which includes a digital micromirror device 2, a temperature sensor 3, a mirror control unit 4, a mirror power supply 5, a mirror control unit power supply 6, a control microcomputer 7, a microcomputer power supply 8, and a connector 9. Furthermore, the circuit board 1 includes a cooling unit power supply, flash memory, a deserializer, and other components.

[0007] like Figure 6 As shown, in a conventional image projection device, multiple electronic components for driving and controlling a digital micromirror device (DMD) are mounted on a circuit board 1. Heat generated by these electronic components increases the temperature surrounding the DMD 2. Since the DMD 2 drives multiple micromirrors to reflect light from a light source, its operating temperature range is limited. Furthermore, operating the DMD 2 in a high-temperature environment shortens its lifespan and reduces its reliability.

[0008] Therefore, to ensure continuous operation of the digital micromirror device 2, the heat dissipation of the circuit substrate 1 must be improved. Consequently, a strategy has been adopted to increase the size of the circuit substrate 1, reduce the mounting density of electronic components, and use a high-performance cooling device to cool the entire image projection device. However, cooling requires an increase in the size of the circuit substrate 1 and the cooling device, making it difficult to meet the demands for miniaturization and weight reduction of image projection devices and vehicle lamps. Summary of the Invention

[0009] Therefore, the present invention has been developed in view of the above-mentioned conventional problems, and an object of the present invention is to provide an image projection device and a vehicle lamp that can achieve miniaturization and weight reduction while suppressing the temperature rise of a digital micromirror device.

[0010] In order to solve the above-mentioned problem, the present invention provides an image projection device, which projects an image by reflecting light from a digital micromirror device having a plurality of tiny mirrors, and is characterized in that it comprises: a reflector mounting substrate on which the digital micromirror device is mounted; a power supply mounting substrate which is formed separately from the reflector mounting substrate; a flexible cable which electrically connects the reflector mounting substrate and the power supply mounting substrate; and a reflector power supply unit which supplies power to the digital micromirror device via the flexible cable, which is mounted on the power supply mounting substrate.

[0011] In the image projection device of the present invention, the reflector mounting substrate and the power supply mounting substrate are electrically connected by a flexible cable, and the power supply unit for the reflector is mounted on the power supply mounting substrate. Therefore, the heat generated by the reflector power supply unit, which is prone to heat, can be prevented from being transferred to the digital micromirror device, thereby suppressing the temperature rise of the digital micromirror device while achieving miniaturization and lightweighting.

[0012] Furthermore, in one aspect of the present invention, a voltage monitoring unit for monitoring a mirror driving voltage supplied to the digital micromirror device is mounted on the mirror mounting substrate.

[0013] In one embodiment of the present invention, a mirror control unit for controlling the digital micromirror device is mounted on the mirror mounting substrate, and a power supply unit for the mirror control unit for supplying power to the mirror control unit is also mounted on the mirror mounting substrate.

[0014] Furthermore, in one aspect of the present invention, a series regulator is used as the power supply unit for the reflecting mirror.

[0015] In one embodiment of the present invention, a temperature sensor unit for measuring the temperature of the digital micromirror device is mounted on the reflector mounting substrate, and a cooling control unit for controlling the driving of the cooling unit based on the measurement value of the temperature sensor unit is mounted on the power supply mounting substrate.

[0016] In addition, in one embodiment of the present invention, the digital micromirror device is mounted on the surface of the reflector mounting substrate, the reflector power supply unit is mounted on the surface of the power supply mounting substrate, and the flexible cable is bent to arrange the reflector mounting substrate and the power supply mounting substrate with their backs facing each other.

[0017] In addition, in one embodiment of the present invention, the digital micromirror device is mounted on the surface of the reflector mounting substrate, the reflector power supply unit is mounted on the surface of the power supply mounting substrate, and the flexible cable is bent to configure the digital micromirror device and the reflector power supply unit facing the same space.

[0018] Furthermore, the present invention provides a vehicle lamp, characterized by comprising: the image projection device described in any one of the above; and a light source unit for irradiating light to the image projection device.

[0019] Effects of the Invention

[0020] The present invention can provide an image projection device and a vehicle lamp that can achieve miniaturization and weight reduction while suppressing a temperature increase of a digital micromirror device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic perspective view showing a configuration example of the vehicle lamp 100 according to the first embodiment.

[0022] Figure 2 1 and 2 are diagrams schematically showing image depictions of the micro-mirrors 11 included in the image projection device 10 in the on and off states.

[0023] Figure 3 It is a schematic plan view showing a configuration example of the image projection device 10 according to the first embodiment.

[0024] Figure 4 1 is a block diagram schematically showing a power supply line of the image projection apparatus 10 according to the first embodiment.

[0025] Figure 5 1 is a schematic diagram showing an example of the configuration of an image projection device 10 according to the second embodiment. Figure 5 (a) shows an example in which the back surfaces of the mirror mounting substrate 101a and the power supply mounting substrate 101b are placed facing each other. Figure 5 (b) shows an example in which the surfaces of the mirror mounting substrate 101 a and the power source mounting substrate 101 b are arranged to face the same space 120 .

[0026] Figure 6 This is a schematic diagram showing the structure of an image projection device used in a conventional vehicle lamp.

[0027] Description of Reference Numerals

[0028] 100 ...Vehicle lamp 10 ...Image projection device

[0029] 11…Reflector

[0030] 20…Light source

[0031] 30…Reflector

[0032] 40…Projection lens

[0033] 50…Radiator

[0034] 60…projection surface

[0035] 101a…Reflector mounting substrate

[0036] 101b…Power supply board

[0037] 102…Digital Micromirror Device

[0038] 103…Temperature sensor unit

[0039] 104…Mirror control unit

[0040] 105…Flash memory

[0041] 106…Power supply for mirror control unit

[0042] 107…Voltage monitoring unit

[0043] 108…Flexible cable

[0044] 109…Power supply for reflector

[0045] 110…Control microcomputer

[0046] 111…Voltage adjustment unit

[0047] 112…Microcomputer power supply unit

[0048] 113…Deserializer

[0049] 114…Cooling power supply

[0050] 115, 116…Connector

[0051] 120…Space DETAILED DESCRIPTION

[0052] (First embodiment)

[0053] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same or equivalent components, members, and processes shown in the respective drawings are denoted by the same reference numerals, and duplicate descriptions are omitted as appropriate. Figure 1 1 is a schematic perspective view showing a structural example of a vehicle lamp 100 according to this embodiment. Figure 1 As shown, the vehicle lamp 100 includes an image projection device 10 , a light source unit 20 , a reflector 30 , a projection lens 40 , and a heat sink 50 , and projects an image onto a projection surface 60 .

[0054] The image projection device 10 controls the reflection direction of light within a surface based on on / off information included in the information about the image being projected, and reflects light emitted from the light source unit 20 as projection light Lon and shielding light Loff. Projection light Lon is irradiated onto the projection surface 60 via the projection lens 40, and an image is projected by irradiating the area corresponding to the on / off information. Shielding light Loff reaches and is shielded by a shielding unit (not shown), preventing it from being irradiated externally.

[0055] The light source unit 20 emits light toward the reflector 30 based on externally supplied power and signals. For example, a light emitting diode (LED) or a semiconductor laser (LASER) can be used. The light emitted from the light source unit 20 can be continuous wave (CW) light, pulsed light, or PWM (Pulse Width Modulation) controlled light.

[0056] The reflector 30 is an optical component that reflects light emitted from the light source 20 toward the image projection device 10. The shape of the reflective surface of the reflector 30 is not limited; a curved surface such as a parabola or an ellipse can be used. The light reflected by the reflector 30 can have its optical path magnified toward the image projection device 10 or can be parallelized.

[0057] The projection lens 40 is an optical component disposed on the optical path of the projection light Lon reflected by the image projection device 10 , and magnifies the projection light Lon and irradiates the projection surface 60 . Figure 1 , an example of using a single lens as the projection lens 40 is shown, but a plurality of lenses may be provided. Figure 1 An example of a convex lens is shown in FIG. 1 , but a well-known lens structure such as a concave lens or an aspherical lens may also be used.

[0058] The heat sink 50 is a component used to support the light source unit 20 and improve heat dissipation. The material of the heat sink 50 is not limited; for example, copper or aluminum with high thermal conductivity, or a highly thermally conductive resin, can be used. The structure and shape of the heat sink 50 are not limited; however, the heat dissipation can be further improved by providing a plurality of fins on the rear surface.

[0059] The projection surface 60 is provided outside the vehicle lamp 100 and is irradiated with the projection light Lon to project an image. Examples of the projection surface 60 include a road surface, a wall surface of a structure, a body of another vehicle, and a body of the vehicle itself. Figure 1 Although a flat surface is shown as the projection surface 60 in FIG. 1 , any surface may be a curved surface or a surface having projections and depressions as long as an image can be projected and displayed by irradiating the projection light Lon.

[0060] Figure 2 1 and 2 are diagrams schematically showing image depictions of the micro-mirrors 11 included in the image projection device 10 in the on and off states. Figure 2 The state where the reflector 11 is kept flat is shown as the off state, but the state where it is tilted to the opposite side of the on state can also be set as the off state. As described later, the image projection device 10 is equipped with a digital micromirror device 102, and in the digital micromirror device 102, a plurality of micromirrors 11 are arranged in a matrix. Figure 2 As shown, the micro-mirrors 11 can change their tilt angles between the on state 11on and the off state 11off, and the tilt angles are controlled in accordance with the on and off information contained in the image. As a result, the light reflection direction of each mirror 11 differs between the on state 11on and the off state 11off, separating the projection light Lon reflected in the on state 11on from the shielding light Loff reflected in the off state 11off. Figure 2 For simplicity, a matrix arrangement of 20 rows and 20 columns is shown as the reflective mirrors 11. However, a high-resolution image can be projected by arranging more reflective mirrors 11. The specific structure of the digital micromirror device 102 is not limited, and a known structure can be used.

[0061] Figure 3 1 is a schematic top view showing a configuration example of the image projection device 10 of this embodiment. Figure 3As shown, the image projection apparatus 10 includes a mirror mounting substrate 101a, a power supply mounting substrate 101b, a digital micromirror device 102, a temperature sensor unit 103, a mirror control unit 104, a flash memory 105, a power supply unit 106 for the mirror control unit, a voltage monitoring unit 107, a flexible cable 108, a power supply unit 109 for the mirror, a control microcomputer 110, a voltage adjustment unit 111, a power supply unit 112 for the microcomputer, a deserializer 113, a power supply unit 114 for cooling, and connector units 115 and 116.

[0062] The mirror mounting substrate 101a and the power supply mounting substrate 101b are circuit substrates on which separately formed electronic components are mounted. They have wiring patterns (not shown) formed on their surfaces and electrically connect the electronic components mounted on the surfaces to form circuits. Figure 3 , an example in which electronic components are mounted only on the front side is shown, but a wiring pattern can also be formed on the back side and electronic components can also be mounted thereon. The materials constituting the reflector mounting substrate 101a and the power supply mounting substrate 101b are not limited, and known printed wiring substrates, etc., can be used. To improve the heat dissipation of the reflector mounting substrate 101a and the power supply mounting substrate 101b, a composite substrate can be used, in which an insulating layer and a wiring pattern are formed on a substrate made of a highly thermally conductive material such as metal or ceramic. Furthermore, the reflector mounting substrate 101a and the power supply mounting substrate 101b can be formed of the same material and the same structure, or they can be formed of different materials or different structures.

[0063] like Figure 3 As shown, the mirror mounting substrate 101a is equipped with a digital micromirror device 102, a temperature sensor unit 103, a mirror control unit 104, a flash memory 105, a mirror control unit power supply unit 106, and a voltage monitoring unit 107. Furthermore, the power supply mounting substrate 101b is equipped with a mirror power supply unit 109, a control microcomputer 110, a voltage adjustment unit 111, a microcomputer power supply unit 112, a deserializer 113, a cooling power supply unit 114, and connectors 115 and 116.

[0064] like Figure 2 As shown, the digital micromirror device 102 is an electronic component that arranges tiny mirrors 11 in a matrix and can change the tilt angle between an on state 11on and an off state 11off. The mirrors 11 separate the projection light Lon reflected in the on state 11on from the shielding light Loff reflected in the off state 11off. The projection light Lon is then irradiated to project an image.

[0065] The temperature sensor unit 103 is an electronic component located near the digital micromirror device 102 and measures the temperature of the digital micromirror device. The temperature measured by the temperature sensor unit 103 is transmitted as temperature information to the mirror control unit 104 and the control microcomputer 110. The specific structure of the temperature sensor unit 103 is not limited; a thermistor, thermocouple, digital temperature sensor, or the like can be used.

[0066] The mirror control unit 104 is an electronic component that transmits a control signal to the digital micromirror device 102 based on the on and off information contained in the image, switching the mirror 11 between the on state 11on and the off state 11off. The mirror control unit 104 is connected to the control microcomputer 110 via a flexible cable 108 and is driven by control signals from the control microcomputer 110. The mirror control unit 104 and the digital micromirror device 102 need to operate at high speeds (e.g., 600 MHz or higher) required for image rendering. Therefore, they are located close to each other on the mirror mounting substrate 101a.

[0067] The flash memory 105 is a storage unit for storing information required for driving the mirror control unit 104. Examples of the information stored in the flash memory 105 include programs executed by the mirror control unit 104, various setting information, image data, and the like.

[0068] The mirror control unit power supply unit 106 is a power supply circuit that supplies power from the voltage regulator unit 111 via the flexible cable 108, thereby supplying power to the mirror control unit 104. A relatively high voltage is supplied to the mirror control unit power supply unit 106 from the voltage regulator unit 111 via the flexible cable 108. The mirror control unit power supply unit 106 uses multiple DC / DC converters to step down the voltage to a voltage suitable for driving the mirror control unit 104, and then outputs the power. Examples of voltage conversion performed by the mirror control unit power supply unit 106 include supplying 6V DC and outputting 3.3V, 1.8V, or 1.1V DC.

[0069] The voltage monitoring unit 107 is an electronic component that monitors the mirror driving voltage supplied from the mirror power supply unit 109 to the digital micromirror device via the flexible cable 108. The voltage monitoring unit 107 is also electrically connected to the mirror control unit 104 and the control microcomputer 110, transmitting the measured value of the monitored voltage. For example, if the voltage on the mirror mounting substrate 101a supplied from the flexible cable 108 falls below a specified value, the mirror control unit 104 stops the operation of the digital micromirror device 102. This allows detection of disconnection or poor connection of the flexible cable 108, failure of the mirror power supply unit 109, and other issues, thereby preventing malfunction of the digital micromirror device 102.

[0070] The flexible cable 108 is a wiring cable in which multiple wirings are collectively protected by a flexible resin or other material. It electrically connects the mirror mounting substrate 101a and the power supply mounting substrate 101b. The connection method between the flexible cable 108 and the mirror mounting substrate 101a and the power supply mounting substrate 101b is not particularly limited, and connectors mounted on the two substrates may be inserted. Because the flexible cable 108 is flexible, it can be bent to ensure electrical connection regardless of the configuration of the two substrates.

[0071] The mirror power supply 109 is a power supply circuit that receives power from outside the image projection apparatus 10 via the connector 115 and supplies power to the digital micromirror device 102 via the flexible cable 108. The mirror power supply 109 is composed of multiple electronic components, including a series regulator and a DC / DC converter. Examples of the output of the mirror power supply 109 include DC 16V, 8.5V, and -10V.

[0072] The control microcomputer 110 is an electronic component that controls the overall operation of the image projection apparatus 10 based on control signals and various measured values. The control microcomputer 110 can communicate with the outside world via the connector 116, supplying image information and control signals from the outside. Furthermore, measured values ​​from the mirror control unit 104, the temperature sensor unit 103, and the voltage monitoring unit 107 are transmitted to the control microcomputer 110.

[0073] When image information is transmitted from the outside, the control microcomputer 110 transmits the image information to the mirror control unit 104 via the flexible cable 108, thereby controlling the on state 11on and the off state 11off of the mirror 11. Furthermore, the control microcomputer 110 controls the driving of a cooling unit (not shown) based on temperature information from the temperature sensor unit 103, thereby controlling the temperature of the digital micromirror device 102. The cooling unit can be a known device such as a cooling fan, a liquid cooling device, or a Peltier element. Furthermore, the control microcomputer 110 controls the driving of the image projection device 10 based on the measured value of the voltage monitoring unit 107. For example, if the signal from the voltage monitoring unit 107 is interrupted, the control microcomputer 110 determines that the flexible cable 108 is disconnected or detached, and stops the output from the mirror power supply unit 109.

[0074] Here, the control microcomputer 110 controls the cooling power supply unit 114 and the cooling unit by executing a pre-recorded program, thereby cooling the image projection apparatus 10. Therefore, it also constitutes the cooling control unit of the present invention. While this example illustrates a portion of the functions of the control microcomputer 110 functioning as the cooling control unit, dedicated electronic components may also be mounted on the power supply mounting substrate 101b to function as the cooling control unit.

[0075] The voltage regulator 111 is a circuit composed of a series regulator and a DC / DC converter, and regulates the voltage in combination with the mirror power supply 109. Examples of voltage conversion performed by the voltage regulator 111 include supplying DC 12V and outputting DC 6V or 3.3V.

[0076] The microcomputer power supply unit 112 is a power supply circuit that receives power from outside the image projection apparatus 10 via the connector unit 115 and supplies power to the control microcomputer 110. The microcomputer power supply unit 112 is composed of a series regulator and outputs DC 3.3V or 5V, for example.

[0077] The deserializer 113 is an electronic component that receives image information from the outside in the form of serial data via the connector 116 , converts the serial data into parallel data, and transmits the parallel data to the mirror control unit 104 .

[0078] The cooling power supply 114 is a power supply circuit that receives power from outside the image projection apparatus 10 via the connector 115 and supplies power to a cooling unit (not shown). The cooling power supply 114 is composed of a series regulator, and an output voltage example is DC 5V.

[0079] Connectors 115 and 116 are electronic components that ensure electrical connection to the outside of the image projection apparatus 10 by inserting cables, etc. In the image projection apparatus 10, power is supplied from the outside to the mirror power supply 109, the microcomputer power supply 112, and the cooling power supply 114 via connector 115. Furthermore, control signals and information are transmitted between the mirror control unit 104 and the control microcomputer 110 and the outside via connector 116.

[0080] like Figure 3 As shown, in the image projection device 10 of this embodiment, the mirror mounting substrate 101a and the power supply mounting substrate 101b are electrically connected via a flexible cable 108, enabling power and control signals to be transmitted between them. However, since the flexible cable 108 has a structure in which the periphery of the electrical wiring is covered with a flexible resin, its thermal conductivity is low, thus suppressing heat conduction between the mirror mounting substrate 101a and the power supply mounting substrate 101b. This prevents heat generated by the electronic components mounted on the power supply mounting substrate 101b from being transferred to the mirror mounting substrate 101a, thereby suppressing temperature increases in the digital micromirror device 102.

[0081] In addition, since the reflector mounting substrate 101a and the power supply mounting substrate 101b are formed separately, by mounting electronic components with lower heat generation on the reflector mounting substrate 101a and electronic components with higher heat generation on the power supply mounting substrate 101b, the temperature rise of the digital micromirror device 102 can be suppressed without enlarging the circuit substrate, and miniaturization and lightweighting can also be achieved.

[0082] Here, an example of an electronic component with low heat generation is the mirror control unit power supply 106. As mentioned above, the mirror control unit power supply 106 is composed of a DC / DC converter, which has high conversion efficiency and therefore generates little heat. Furthermore, a DC / DC converter has high current capacity and good responsiveness to load (current) fluctuations, but this increases the number of components that make up the circuit and the mounting area. However, in the image projection device 10 of this embodiment, by also mounting the electronic components on the power supply mounting substrate 101b, it is easier to secure an area on the mirror mounting substrate 101a for the mirror control unit power supply 106.

[0083] Examples of electronic components that generate a large amount of heat include the reflector power supply 109, the voltage regulator 111, the microcomputer power supply 112, and the cooling power supply 114. As mentioned above, the reflector power supply 109, the voltage regulator 111, the microcomputer power supply 112, and the cooling power supply 114 comprise series regulators, which have low conversion efficiency and therefore generate a large amount of heat. Series regulators have low current capacity and are less responsive to load (current) fluctuations than DC / DC converters, but can be constructed from a single chip, thus reducing the mounting area. In the image projection device 10 of this embodiment, by mounting the series regulator on the power supply mounting substrate 101b, which is separate from the reflector mounting substrate 101a, the temperature rise of the digital micromirror device 102 can be suppressed. Furthermore, by mounting the series regulator, which can be constructed from a single chip, on the power supply mounting substrate 101b, the mounting density of the electronic components on the power supply mounting substrate 101b can be reduced, thereby suppressing the temperature rise on the power supply mounting substrate 101b.

[0084] As other electronic components, the mirror control unit 104 requires shorter wiring to achieve the same high-speed operation as the digital micromirror device 102 and is therefore mounted on the mirror mounting substrate 101a close to the digital micromirror device 102. Furthermore, the temperature sensor unit 103 is mounted on the mirror mounting substrate 101a close to the digital micromirror device 102 to measure the temperature of the digital micromirror device 102. Furthermore, the flash memory 105 needs to transmit information such as image information and programs between it and the mirror control unit 104 and is therefore mounted on the mirror mounting substrate 101a close to the mirror control unit 104. Furthermore, the voltage monitoring unit 107 is a device for detecting abnormalities in the voltage supplied to the mirror mounting substrate 101a and is therefore mounted on the mirror mounting substrate 101a.

[0085] The control microcomputer 110 does not require the high-speed operation of the digital micromirror device 102. It needs to communicate information with the outside world via the connector 115 while maintaining continued operation even if a malfunction occurs in the flexible cable 108. Therefore, it is mounted on the power supply board 101b. A deserializer 113 is mounted on the power supply board 101b to convert serial data transmitted via the connector 116 into parallel data and transmit it to the mirror control unit 104.

[0086] Figure 4 This is a block diagram schematically showing the power supply line of the image projection device 10 of this embodiment. The power supplied from the outside via the connector 115 is transmitted to the power supply unit 109 for the reflector, the power supply unit 112 for the microcomputer, and the power supply unit 114 for cooling. As the power supplied from the outside, DC12V supplied from the battery for vehicle use can be cited. Figure 4 In the example shown, the microcomputer power supply 112 includes two series regulators, each outputting 3.3V for driving the microcomputer 110 and 5V for driving the interface unit. The interface power supply is used to control the input and output signals of the external device (LED Driver Module) that drives the LEDs used as light sources (LDM). The cooling power supply 114 includes a single series regulator, outputting 5V for driving the cooling fan and other components.

[0087] The mirror power supply unit 109 and the voltage regulator 111 include multiple DC / DC converters and multiple series regulators, and regulate the voltage output via the flexible cable 108. The voltage regulator 111 boosts the externally supplied 12V to 20V using a primary DC / DC converter, then steps it down to 6V using a secondary DC / DC converter, and outputs the voltage. Part of the output from the secondary DC / DC converter is supplied to the mirror control unit power supply unit 106 via the flexible cable 108, while the remaining part is supplied to the series regulators in the voltage regulator 111 and the mirror power supply unit 109. The series regulators in the voltage regulator 111 convert the 6V to 3.3V and supply it to the mirror power supply unit 109. The mirror power supply unit 109 generates 16V, 8.5V, and -10V from the supplied 6V and 3.3V, and supplies these to the digital micromirror device 102 via the flexible cable 108.

[0088] The mirror power supply unit 109 includes three DC / DC converters, and converts 6V supplied via the flexible cable 108 into 1.1V, 1.8V, and 3.3V, respectively, and supplies the converted voltages to the mirror control unit 104 . 1.8V output is also supplied to the digital micromirror device 102 .

[0089] As described above, in the image projection device 10 of this embodiment, the reflector mounting substrate 101a and the power supply mounting substrate 101b are electrically connected via the flexible cable 108, and the power supply unit 109 for the reflector is mounted on the power supply mounting substrate 101b. Therefore, it is possible to prevent heat generated by the reflector power supply unit 109, which is prone to heat, from being transferred to the digital micromirror device 102, thereby achieving miniaturization and lightweighting while suppressing the temperature rise of the digital micromirror device 102.

[0090] Furthermore, by mounting a voltage monitoring unit 107 on the mirror mounting substrate 101a to monitor the mirror driving voltage supplied to the digital micromirror device 102, if a defect such as a break or detachment of the flexible cable 108 occurs, the driving of the digital micromirror device 102 can be stopped to prevent malfunctions.

[0091] Furthermore, the mirror mounting substrate 101a houses a mirror control unit 104 that controls the digital micromirror device 102. Also housed on the mirror mounting substrate 101a is a mirror control unit power supply unit 106 that supplies power to the mirror control unit 104. Since the mirror control unit power supply unit 109 is mounted on the power supply mounting substrate 101b, the number of electronic components mounted on the mirror mounting substrate 101a is reduced, enabling a reduction in size while ensuring sufficient mounting area for the mirror control unit power supply unit 106. Furthermore, even if the mirror control unit power supply unit 106 is comprised of a DC / DC converter, which generates relatively little heat but requires a relatively large mounting area, sufficient mounting area can still be ensured.

[0092] Furthermore, the mirror power supply unit 109 is constructed on a single chip using a DC / DC converter and a series regulator, thereby reducing the mounting area. A series regulator has low conversion efficiency and therefore generates a large amount of heat. However, by mounting the series regulator only on the power supply mounting substrate 101b, heat transfer to the digital micromirror device 102 and a temperature increase can be prevented.

[0093] Furthermore, the mirror mounting substrate 101a includes a temperature sensor unit 103 for measuring the temperature of the digital micromirror device 102, and the power supply mounting substrate 101b includes a cooling control unit for controlling the operation of the cooling unit based on the value measured by the temperature sensor unit 103. By also mounting the cooling control unit on the power supply mounting substrate 101b and mounting the cooling power supply unit 114, which is comprised of a series regulator that generates a large amount of heat, on the power supply mounting substrate 101b, heat transfer to the digital micromirror device 102 can be suppressed.

[0094] (Second embodiment)

[0095] Next, use Figure 5 A second embodiment of the present invention will be described, with the description of the contents overlapping with the first embodiment omitted. Figure 5 1 is a schematic diagram showing an example of the configuration of the image projection device 10 according to the present embodiment. Figure 5 (a) shows an example in which the back surfaces of the mirror mounting substrate 101a and the power supply mounting substrate 101b are placed facing each other. Figure 5 (b) shows an example in which the surfaces of the mirror mounting substrate 101 a and the power source mounting substrate 101 b are arranged to face the same space 120 .

[0096] exist Figure 5 In the example shown in (a), the back surfaces of the reflector mounting substrate 101a and the power supply mounting substrate 101b are arranged to face each other, thereby reducing the space occupied by the image projection device 10 and achieving miniaturization. In addition, since the reflector mounting substrate 101a and the power supply mounting substrate 101b are close to each other, they can be efficiently cooled by a single cooling unit, which can reduce the number of parts and achieve miniaturization. Figure 5 In the example shown in (a), a space is provided between the back surfaces of the mirror mounting substrate 101a and the power supply mounting substrate 101b. However, a common heat sink may be provided between the back surfaces.

[0097] exist Figure 5In the example shown in (b), the surfaces of the reflector mounting substrate 101a and the power supply mounting substrate 101b are arranged to face the same space 120. This ensures that the space 120 is used for irradiating the digital micromirror device 102 with light from the light source unit. Furthermore, an optical path for projecting the projection light Lon reflected by the digital micromirror device 102 can be ensured through the space 120. Furthermore, it is also possible to mount the light source unit 20 on the power supply mounting substrate 101b and irradiate the digital micromirror device 102 with light from the surface of the power supply mounting substrate 101b through the space 120. This eliminates the need for separately providing the light source unit 20 and the heat sink 50 outside the image projection device 10, thereby reducing the number of components and miniaturizing the device.

[0098] As described above, in the image projection device 10 of this embodiment, the digital micromirror device 102 is mounted on the surface of the mirror mounting substrate 101a, the mirror power supply unit 109 is mounted on the surface of the power mounting substrate 101b, and the flexible cable 108 is bent so that the mirror mounting substrate 101a and the power mounting substrate 101b are arranged with their back surfaces facing each other. This can reduce the number of components and achieve miniaturization.

[0099] Furthermore, the digital micromirror device 102 is mounted on the surface of the mirror mounting substrate 101a, the mirror power supply unit 109 is mounted on the surface of the power supply mounting substrate 101b, and the flexible cable 108 is bent so that the digital micromirror device 102 and the mirror power supply unit 109 face the same space. This ensures an optical path, reduces the number of components, and achieves miniaturization.

[0100] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Claims

1. An image projection device, which projects an image by reflecting light from a digital micromirror device having a plurality of micro-mirrors, characterized in that: have: a light source portion that radiates light; A reflector that reflects light irradiated from the light source portion toward the digital micromirror device; A reflector mounting substrate, on which the digital micromirror device is mounted; A power supply mounting substrate, which is formed separately from the reflector mounting substrate; a flexible cable electrically connecting the reflector mounting substrate and the power supply mounting substrate; A power supply unit for a reflecting mirror is mounted on the power supply mounting substrate, and supplies power to the digital micromirror device via the flexible cable. A mirror control unit for controlling the digital micromirror device is mounted on the mirror mounting substrate. A power supply unit for a mirror control unit that supplies electric power to the mirror control unit is also mounted on the mirror mounting substrate.

2. The image projection device according to claim 1, characterized in that: A voltage monitoring unit that monitors a mirror driving voltage supplied to the digital micromirror device is mounted on the mirror mounting substrate.

3. The image projection device according to claim 1 or 2, characterized in that: A series regulator is used as the power supply unit for the reflecting mirror.

4. The image projection device according to claim 1 or 2, characterized in that: A temperature sensor unit for measuring the temperature of the digital micromirror device is mounted on the reflector mounting substrate. A cooling control unit that controls driving of a cooling unit based on a measurement value of the temperature sensor unit is mounted on the power source mounting substrate.

5. The image projection device according to claim 1 or 2, characterized in that: The digital micromirror device is mounted on the surface of the reflector mounting substrate. The power supply unit for the reflector is mounted on the surface of the power supply mounting substrate. The flexible cable is bent to arrange the reflector mounting substrate and the power source mounting substrate so that their back surfaces face each other.

6. The image projection device according to claim 1 or 2, characterized in that: The digital micromirror device is mounted on the surface of the reflector mounting substrate. The power supply unit for the reflector is mounted on the surface of the power supply mounting substrate. The flexible cable is bent to arrange the digital micromirror device and the power supply unit for the reflecting mirror facing the same space.

7. A vehicle lamp, characterized in that: have: The image projection device according to any one of claims 1 to 6; A light source unit irradiates light to the image projection device.

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