WO2023145380A1

WO2023145380A1 - Lighting device, head-up display, and method for manufacturing lighting device

Info

Publication number: WO2023145380A1
Application number: PCT/JP2022/048481
Authority: WO
Inventors: 克彦谷本; 滋小島; 智子佐々木
Original assignee: 日本精機株式会社
Priority date: 2022-01-26
Filing date: 2022-12-28
Publication date: 2023-08-03

Abstract

Provided are a lighting device, a head-up display, and a method for manufacturing lighting device, capable of appropriately maintaining a moisture-proof sealed state of an internal space. A back-light unit 1 comprises a laser light source 11 for outputting laser light, a Peltier module 17 for cooling the laser light source 11, and an outer case 18 for internally sealing the laser light source 11 and the Peltier module 17 against moisture, wherein: the outer case 18 comprises a tubular accommodating portion 181 having an emission opening 1811 for emitting the laser light formed therein, a lower lid portion 183 which is in thermal contact with the Peltier module 17 and which blocks one opening of the accommodating portion 181, and an upper lid portion 182 which blocks another opening of the accommodating portion 181; and an internal space S in a negative pressure state is formed in the accommodating portion 181.

Description

LIGHTING DEVICE, HEAD-UP DISPLAY, AND LIGHTING DEVICE MANUFACTURING METHOD

The present disclosure relates to lighting devices, head-up displays, and methods of manufacturing lighting devices.

In a lighting device that cools a laser light source with a Peltier element, if the area cooled by the Peltier element is exposed to high-humidity air, condensation will occur and cause electrical circuit failure. It has been proposed to seal a case containing the in a moisture-proof manner (see Patent Document 1).

WO2017/104018

However, in Patent Document 1, the manufacturing procedure and structure for moisture-proof sealing are not clarified, and there is room for improvement in the configuration for keeping the quality of the sealing structure constant.

Therefore, an object of the present disclosure is to provide a lighting device, a head-up display, and a manufacturing method of the lighting device that can appropriately maintain the moisture-proof sealed state of the internal space.

One aspect provides the following solutions.
(1) A lighting device comprising: a laser light source that outputs a laser light; a Peltier module that cools the laser light source; and a case that seals the laser light source and the Peltier module inside against moisture, a cylindrical accommodating portion having an exit opening for emitting the laser light; a first lid portion that is in thermal contact with the Peltier module and closes one opening of the accommodating portion; and the other opening of the accommodating portion. and a second lid that closes the housing, and a negative pressure space is formed in the housing.
(2) In the configuration of (1) above, the second lid portion is formed with an inspection hole for inspecting airtightness of the accommodating portion.
(3) In the configuration of (2) above, the inspection hole is sealed with a sealing member after the inspection.
(4) In any one of the configurations (1) to (3) above, a translucent window cover is fixed to the outer wall of the housing to cover the exit port.
(5) A head-up display, comprising: a lighting device according to any one of claims 1 to 4; a lens for collimating illumination light output from the lighting device; and illumination light passing through the lens. and an illuminated liquid crystal panel.
(6) A method for manufacturing a lighting device, comprising: a housing step of housing a laser light source and a Peltier module in a housing portion of a case having an opening; a negative pressure step of making the housing portion into a negative pressure state; and a sealing step of sealing.
(7) In the method of (6) above, the negative pressure step is characterized in that the negative pressure state is created by setting the accommodating portion to a first temperature higher than room temperature.

According to the present disclosure, it is possible to appropriately maintain the moisture-proof sealed state of the internal space.

1 is a schematic configuration diagram of a head-up display; FIG. 2 is a schematic configuration diagram of an image display device; FIG. It is a perspective view of an illuminating device. It is a component structure perspective view of an illuminating device. It is a principal part perspective view of an illuminating device. FIG. 11 is a perspective view of a main part of the lighting device viewed from another angle; 4 is a cross-sectional view of the lighting device (a cross-sectional view taken along the line AA in the XY plane of FIG. 3); FIG. FIG. 4 is a cross-sectional view of the illumination device (cross-sectional view taken along the line BB in the YZ plane of FIG. 3); FIG. 4 is a cross-sectional view of the lighting device (CC cross-sectional view in the XZ plane of FIG. 3); (a) is an enlarged cross-sectional view of an inspection hole, and (b) is a perspective view showing another example of the sealing structure of the inspection hole. 1 is a schematic configuration diagram of an inspection device; FIG.

Each embodiment will be described in detail below with reference to the accompanying drawings.

(Structure of head-up display H)
The head-up display H is built in the instrument panel of the vehicle, and is an in-vehicle instrument that displays various vehicle information such as vehicle traveling speed, various warning information, and route guidance information to the occupant P of the vehicle.

See Figure 1. The head-up display H includes an image display D, a reflector M, a control circuit board B, and a case C. The head-up display H displays an image representing vehicle information on the image display device D, and projects display light DL output from this image toward the windshield WS of the vehicle. A passenger P can visually recognize a virtual image V representing vehicle information in front of the windshield WS.

The image display D displays an image that expresses the vehicle information using numerical values, diagrams, and the like. The image display device D incorporates the illumination device 1, and the detailed configuration thereof will be described later.

The reflector M is, for example, a concave mirror. The reflecting mirror M can extend the optical path length of the display light DL by folding back the display light DL output from the image display device D within the case C. FIG. The longer the optical path length, the farther the virtual image V is formed from the windshield WS, and the farther the virtual image V can be displayed. Moreover, the distortion of the virtual image V can be suppressed by the reflecting mirror M having a curved surface shape that offsets the distortion of the virtual image V due to the curved shape of the windshield WS. In addition, the reflecting mirror M is not limited to one concave mirror, and may be composed of a plurality of plane mirrors and concave mirrors to turn back light a plurality of times.

The control circuit board B is a circuit board having a control circuit for controlling various electronic components built into the image display device D.

The case C accommodates the image display D, reflector M, and control circuit board B. Case C includes a lower case LC and an upper case UC.

The lower case LC is a metal container such as aluminum die-cast or magnesium die-cast, and the inner surface is painted black to suppress reflection.

The upper case UC is a lid made of resin, and is molded from a resin such as polycarbonate colored black to suppress reflection. The upper case UC is formed with an emission port for emitting the display light DL. To prevent dust from entering the case C through this outlet, the outlet is covered with a transparent dustproof cover UC1. The dustproof cover UC1 is a transparent resin film such as acrylic resin with a thickness of 0.5 to 2 mm (millimeters). Further, in the vicinity of the exit opening of the upper case UC, a light shielding wall UC2 is formed on the inner surface to prevent external light (mainly sunlight) EL entering from the exit opening from directly entering the image display device D. there is

(Configuration of image display device D)
Please refer to FIG. The image display device D includes a backlight unit (illumination device) 1 , a rotating diffusion plate 2 , a lens 3 and a liquid crystal panel 4 .

The backlight unit 1 is a lighting device that outputs coherent white laser light WL, and illuminates the liquid crystal panel 4 . The control circuit board B adjusts and controls the white balance of the white laser light WL. This adjustment control controls the current value of each built-in light source according to the temperature of the built-in light source. A detailed configuration of the backlight unit 1 will be described later.

The rotating diffusion plate 2 is a speckle suppression unit for reducing speckle noise in a speckle pattern that occurs when illuminating an object with coherent laser light. The rotating diffusion plate 2 includes a disk-shaped diffusion plate 21 and a drive unit 22 that rotates the diffusion plate 21 . As shown in FIG. 3 , the rotary diffusion plate 2 is fixed to the backlight unit 1 and diffuses the white laser light WL output by the backlight unit 1 with the diffusion plate 21 . By rotating the rotary diffuser plate 2 and diffusing the white laser light WL emitted from the backlight unit 1 at different locations on the diffuser plate 21, the white laser light WL has various scattering patterns and speckle noise is reduced. Suppressed.

The rotating diffuser plate 2 is fixed to the housing of the backlight unit 1 so that the diffuser plate 21 faces the exit port of the backlight unit 1 . More specifically, the rotary diffusion plate 2 is fixed to the housing portion 181 with screws while being supported by a mounting portion 1812 formed outside the housing portion 181 of the outer case 18 to be described later.

The lens 3 is a lens for collimating the light of the white laser light WL that has passed through the rotating diffusion plate 2 to uniformly illuminate the surface of the liquid crystal panel 4 . Lens 3 includes at least a collimating lens and may also include a lens of a Koehler illumination system.

The liquid crystal panel 4 is a TFT (Thin Film Transistor) type liquid crystal panel. The liquid crystal panel 4 displays figures and numbers representing vehicle information as images, and outputs display light DL from the displayed image by being illuminated with white laser light WL collimated by the lens 3 from the back.

The liquid crystal panel 4 is arranged at a first angle θ1 with respect to the optical axis of the white laser light WL. The first angle θ1 is set so that the external light EL reflected by the reflecting mirror M is reflected by the liquid crystal panel 4 and then directed toward the inner wall of the case C (for example, the light shielding wall UC2). This prevents the external light EL from being reflected by the liquid crystal panel 4, reflected again by the reflecting mirror M, projected onto the windshield WS, and becoming stray light. The first angle θ1 is, for example, an angle of 0 degrees or more and less than 30 degrees.

(Configuration of backlight unit 1)
Please refer to FIGS. 4-9. The backlight unit 1 includes a laser light source 11 , wiring 12 , collimator lens 13 , dichroic mirror 14 , heat sink 15 , inner case 16 , Peltier module 17 and outer case 18 .

The laser light source 11 includes a blue laser light source 11B, a green laser light source 11G, and a red laser light source 11R.

The blue laser light source 11B is a laser diode that outputs blue light with a center wavelength of approximately 632 nm (nanometers).

The green laser light source 11G is a laser diode that outputs green light with a center wavelength of approximately 532 nm (nanometers).

The red laser light source 11R is a laser diode that outputs red light with a central wavelength of approximately 488 nm (nanometers).

The wiring 12 is a flexible printed board on which circuit wiring for lighting the laser light source 11 and a thermistor for detecting temperature are mounted. The wiring 12 includes a first wiring 12B and a second wiring 12GR.

The first wiring 12B is mounted with a circuit wiring for lighting the blue laser light source 11B and a first thermistor Th1 for detecting the temperature of the blue laser light source 11B.

The second wiring 12GR is mounted with a circuit wiring for lighting the green laser light source 11G, a circuit wiring for lighting the red laser light source 11R, and a second thermistor Th2 for detecting the temperatures of the green laser light source 11G and the red laser light source 11R. there is

The collimator lens 13 expands the beam spot diameter of the laser light source 11 . The collimator lens 13 includes a first collimator lens 13B for collimating light from the blue laser light source 11B, a second collimator lens 13G for collimating light from the green laser light source 11G, a third collimator lens 13R for collimating light from the red laser light source 11R, Prepare.

The dichroic mirror 14 is a mirror that reflects light of a predetermined wavelength and transmits light of other wavelengths. Dichroic mirror 14 is manufactured by applying a dielectric coating to a substrate such as, for example, borosilicate crown optical glass. The dichroic mirror 14 includes a first dichroic mirror 141 that reflects green light and a second dichroic mirror 142 that reflects green light and blue light.

The heat sink 15 supports the laser light source 11 and wiring 12, and transfers the heat of the laser light source 11 to other members. The heat sink 15 is made of a material with high thermal conductivity such as die-cast aluminum or die-cast magnesium. The heat sink 15 has a first heat sink 151 and a second heat sink 152 .

The first heat sink 151 has a flat plate-shaped heat radiating portion 1511 and a flat plate-shaped support portion 1512 extending perpendicularly to the heat radiating portion 1511 . The blue laser light source 11B and the first wiring 12B are fixed to the supporting portion 1512 . As shown in FIG. 7, the heat radiating portion 1511 is in thermal contact with a housing portion 181 of the outer case 18, which will be described later. The first heat sink 151 does not come into contact with the Peltier module 17 and the upper lid portion 182 and the lower lid portion 183 of the outer case 18, which will be described later. When the heat radiating portion 1511 and the housing portion 181 are brought into thermal contact with each other, it is preferable that the heat radiating portion 1511 and the housing portion 181 are in thermal contact with each other via a thermally conductive medium such as thermal paste. good.

The second heat sink 152 has a flat plate-shaped heat radiating portion 1521 and a flat plate-shaped support portion 1522 extending perpendicularly to the heat radiating portion 1521 . A green laser light source 11G, a red laser light source 11R, and a second wiring 12GR are fixed to the supporting portion 1522 . As shown in FIG. 8, the heat dissipation part 1521 is in thermal contact with the Peltier module 17, and the heat of the green laser light source 11G and the red laser light source 11R is transmitted to the Peltier module 17 and radiated. In the thermal contact, the heat radiating part 1521 and the Peltier module 17 are thermally contacted via a thermal paste 17a, which will be described later, but they may be configured to be in direct contact with each other.

The inner case 16 is a case made of resin whose thermal conductivity is superior to that of the heat sink 15 and the outer case 18 . The inner case 16 is, for example, PPS (polyphenylene sulfide) resin with a thermal conductivity of 0.29 W/(m·K), and the heat sink 15 and outer case 18 are made of ADC 12 (aluminum) with a thermal conductivity of 96 W/(m·K). An example of die casting), the thermal conductivity is superiorly low compared to the case where it is selected. The inner case 16 accommodates the laser light source 11, the collimator lens 13, and the dichroic mirror 14 so that the light of each color from the laser light source 11 is collimated by the collimator lens 13 and then synthesized into white laser light by the dichroic mirror 14. do.

The inner case 16 has a housing portion 161 . A first inlet 162 , a second inlet 163 , a third inlet 164 , a first outlet 165 , a second outlet 166 , and a third outlet 167 are formed in the side wall of the accommodating portion 161 . The first entrance 162 and the third exit 167 are formed to face each other. The second entrance 163 and the second exit 166 are formed to face each other. The third entrance 164 and the first exit 165 are formed to face each other. A line connecting the second entrance 163 and the second exit 166 and a line connecting the third entrance 164 and the first exit 165 are substantially parallel to each other. The line connecting the first inlet 162 and the third outlet 167 is the line connecting the second inlet 163 and the second outlet 166, and the line connecting the third inlet 164 and the first outlet 165. It is in a positional relationship that is substantially orthogonal to.

The first dichroic mirror 141 is fixed at a position of the housing portion 161 corresponding to the intersection of a line connecting the first entrance 162 and the third exit 167 and a line connecting the second entrance 163 and the second exit 166 . be.

The second dichroic mirror 142 is fixed at a position of the housing portion 161 corresponding to the intersection of a line connecting the first entrance 162 and the third exit 167 and a line connecting the third entrance 164 and the first exit 165 . be.

In the inner case 16, the blue laser light source 11B is fixed to the housing portion 161 in a state in which the blue laser light source 11B is inserted into the housing portion 161 from the first inlet 162. Further, the green laser light source 11G is fixed to the housing portion 161 in a state where the green laser light source 11G is inserted into the housing portion 161 from the second inlet 163 . Furthermore, the red laser light source 11R is fixed to the housing portion 161 in a state where the red laser light source 11R is inserted into the housing portion 161 from the third entrance 164 .

The first collimator lens 13B is fixed to the housing portion 161 so as to be positioned between the blue laser light source 11B and the first dichroic mirror 141.

The second collimator lens 13G is fixed to the housing portion 161 so as to be positioned between the green laser light source 11G and the first dichroic mirror 141.

The third collimator lens 13R is fixed to the housing portion 161 so as to be positioned between the red laser light source 11R and the second dichroic mirror 142.

The laser light source 11, the collimator lens 13, and the dichroic mirror 14 housed in the housing portion 161 of the inner case 16 synthesize the white laser light WL as follows. The blue light emitted by the blue laser light source 11 B is transmitted through the first dichroic mirror 141 and then reflected by the second dichroic mirror 142 toward the first exit port 165 . The green light emitted by the green laser light source 11G is reflected by the first dichroic mirror 142 and the second dichroic mirror 142 and travels toward the first exit port 165 . The red light emitted by the red laser light source 11</b>R passes through the second dichroic mirror 142 and travels toward the first exit 165 . In this way, the blue light, green light, and red light are synthesized as white laser light WL in the process of passing through the accommodation portion 161 of the inner case 16 and heading toward the first emission port 165 .

However, if a laser beam of an unintended wavelength passes through or is reflected by the dichroic mirror 14 and irradiates the inner wall of the inner case 16, the inner case 16 made of resin may melt, adversely affecting the function of the lighting device 1. have a nature. This is because, for example, a laser beam with a different wavelength than expected is emitted from the laser light source 11 to the dichroic mirror 14 due to an incorrect assembly such as reverse assembly of the blue laser light source 11B and the red laser light source 11R, or a defect or failure of the laser light source 11. occurs when Alternatively, it may occur due to misassembly or failure of the dichroic mirror 14 .

In consideration of the above points, the inner case 16 is formed with a second outlet 166 and a third outlet 167 . As a result, as indicated by the dotted line arrow in FIG. 9, when the laser light travels along an unexpected optical path in a direction other than the first emission port 165, the laser light is directed to the second emission port 166 of the inner case 16 or The light passes through the third outlet 167 and irradiates the inner wall of the outer metallic outer case 18 (more specifically, the inner wall of the accommodating portion 181 of the outer case 18 to be described later). Therefore, melting of the inner case 16 made of resin can be prevented.

The Peltier module 17 has a thermoelectric element that has the function of transferring heat from one surface to the other by the Peltier effect. One surface of the Peltier module 17 is in thermal contact with the second heat sink 152, and the other surface is in thermal contact with the lower lid portion 183 of the outer case 18, which will be described later. The Peltier module 17 has one surface coated with thermal paste 17a and the other surface coated with thermal paste 17b. That is, the Peltier module 17 and the second heat sink 152 are in thermal contact with each other through the thermal paste 17a. The Peltier module 17 and the lower lid portion 183 are in thermal contact with each other via the thermal paste 17b.

Here, the inventor of the present disclosure believes that when the lighting device 1 is mounted on an on-vehicle instrument like the head-up display H of the present embodiment, the surrounding environment of the on-vehicle instrument (specifically, inside the instrument panel) was assumed to be hot and humid. If the surrounding environment has high humidity, the Peltier module 17 may be exposed to high humidity air and may condense, and the condensation may adversely affect the function of the lighting device 1. The inventor has recognized.

The outer case 18 is a case that accommodates the laser light source 11, the wiring 12, the collimator lens 13, the dichroic mirror 14, the heat sink 15, the inner case 16, and the Peltier module 17.

The internal space S of the outer case 18 is hermetically sealed in a state where humidity is controlled during manufacturing. That is, the internal space S is a moisture-proof sealed space. Due to this internal space S, the aforementioned Peltier module 17 is not exposed to high-humidity air and no dew condensation occurs.

The outer case 18 has a housing portion 181 , an upper lid portion 182 (second lid portion), a lower lid portion 183 (first lid portion), a seal portion 184 and a window cover portion 185 .

The housing portion 181 is a cylindrical case with openings formed on the upper and lower surfaces. The accommodating portion 181 is formed with an exit port 1811 . A recessed mounting portion 1812 is formed around the exit port 1811 on the outer wall of the housing portion 181 .

A first inclined portion 1813 and a second inclined portion 1814 are formed on the inner wall of the housing portion 181 . The first inclined portion 1813 is formed at a position facing the second outlet 166 of the inner case 16 . The second inclined portion 1814 is formed at a position facing the third outlet 167 of the inner case 16 . The first inclined portion 1813 is inclined so that unintended laser light emitted from the second emission port 166 is not reflected by the inner wall of the housing portion 181 and returned to the first dichroic mirror 141 along the same optical path. Second inclined portion 1814 is inclined so that unintended laser light emitted from third outlet 167 does not reflect on the inner wall of housing portion 181 and return to second dichroic mirror 142 along the same optical path.

In addition, the surfaces of the first inclined portion 1813 and the second inclined portion 1814 have fine uneven shapes (so-called embossed shapes). As a result, unintended laser light is diffused, and melting due to convergence is less likely to occur.

The housing portion 181 supports and houses the inner case 16 so that the first exit port 165 of the inner case 16 faces the exit port 1811 . Further, the accommodation portion 181 accommodates the Peltier module 17 below the inner case 16 so that the second heat sink 152 and the Peltier module 17 are in thermal contact with each other.

The upper lid portion 182 is adhesively fixed (sealed and fixed) to the housing portion 181 so as to cover the opening on the upper surface side of the housing portion 181 from the outside. The lower lid portion 183 is adhesively fixed (sealed and fixed) to the housing portion 181 with a seal portion 184 interposed therebetween so as to cover the opening on the lower surface side of the housing portion 181 from the outside. The window cover part 185 covers the emission port 1811 from the outside, and is inclined at a second angle θ2 with respect to the optical axis of the white laser light WL emitted from the first emission port 165 of the inner case 16 . As shown in FIG. The second angle θ2 is, for example, 1 to 5 degrees.

The housing portion 181, the upper lid portion 182, and the lower lid portion 183 are molded from a material with high thermal conductivity such as aluminum die-cast or magnesium die-cast.

The sealing portion 184 is a sealing material interposed between the accommodating portion 181 and the lower lid portion 183 for the purpose of inhibiting heat transfer between the accommodating portion 181 and the lower lid portion 183 . The sealing portion 184 is a sealing member made of a material having a significantly lower thermal conductivity than the housing portion 181 and the upper lid portion 182 . The seal part 184 is, for example, a rubber packing made of PTFE (polytetrafluoroethylene) resin with a thermal conductivity of 0.23 W/(m·K), and is attached to the heat sink 15 and the outer case 18 with a thermal conductivity of 96 W/(m·K). Compared to the case where ADC12 (an example of aluminum die-casting) is selected, the thermal conductivity is superiorly low. Note that the sealing portion 184 may be a thermosetting adhesive or a UV curing adhesive made of a material with low thermal conductivity.

The window cover part 185 is a transparent plate such as borosilicate crown optical glass. The window cover part 185 is arranged so that the window cover part 185 is inclined at the second angle θ2 with respect to the optical axis of the white laser light WL. Accordingly, even if light enters the window cover portion 185 from the outside, the light reflected by the window cover portion 185 does not become stray light.

As described above, the heat of the blue laser light source 11B of the backlight unit 1 is transmitted to the housing portion 181 of the outer case 18 and radiated. On the other hand, the heat of the red laser light source 11R and the green laser light source 11G of the backlight unit 1 is transferred from the lower lid portion 183 to the lower case LC by the Peltier module 17 and radiated.

When synthesizing the white laser light WL, the power of the laser light output from the blue laser light source 11B is smaller than the power of the other laser light sources (the red laser light source 11R and the green laser light source 11G). Therefore, there is no need to cool the blue laser light source 11B with the Peltier module 17, and the operation can be sufficiently ensured with the configuration in which the heat is dissipated from the accommodating portion 181 of the outer case 18 to the air inside the case C. In other words, the above configuration can reduce the number of light sources to be cooled by the Peltier module 17, resulting in an inexpensive configuration.

Also, the heat transfer between the accommodation portion 181 and the lower lid portion 183 of the outer case 18 is inhibited by the sealing portion 184 .

With this configuration, the heat generated when the Peltier module 17 adjusts the temperature of the red laser light source 11R and the green laser light source 11G does not adversely affect the temperature of the blue laser light source 11B. Also, the heat generated when the temperature of the red laser light source 11R and the green laser light source 11G is adjusted by the Peltier module 17 flows into the blue laser light source 11B, which adversely affects the temperature adjustment control of the red laser light source 11R and the green laser light source 11G. never comes out. Overall, this contributes to increasing the accuracy of temperature adjustment control of the laser light source 11 by the Peltier module 17 . It also contributes to increasing the accuracy of brightness adjustment control of the laser light source 11 that requires temperature adjustment control.

(Moisture-proof sealing maintenance structure of backlight unit 1)
Next, a moisture-proof sealed state maintenance structure of the backlight unit 1 of the present disclosure will be described with reference to FIGS. 3 to 10. FIG.

The internal space S of the outer case 18 is a negative pressure space. That is, the air pressure inside the outer case 18 is lower than the air pressure outside the outer case 18 . When the internal space S is made into a negative pressure space, an external pressure acts on the upper lid portion 182, the lower lid portion 183, and the window cover portion 185 sealed and fixed from the outside. This external pressure makes it difficult for these lids (the upper lid portion 182, the lower lid portion 183, and the window cover portion 185) to come off, so that the moisture-proof sealed state of the backlight unit 1 can be maintained satisfactorily. A method of making the internal space S of the outer case 18 into a negative pressure state will be described later.

In addition, an inspection hole 1821 for inspecting the airtightness of the internal space S is formed in the upper lid portion 182 . The inspection hole 1821 is a hole that communicates the internal space S and the external space of the outer case 18, and enables an airtightness inspection of the internal space S using an inspection device 500 (see FIG. 11) or the like in the manufacturing process. A method of airtightness inspection of the internal space S will be described later.

As shown in FIG. 10, the inspection hole 1821 is sealed after the airtightness inspection of the internal space S is performed. In the example shown in FIG. 10A, a photocurable resin 1822 and a thermosetting resin 1823 are used as sealing materials. First, temporary sealing is performed with a photocurable resin 1822 to prevent the thermosetting resin 1823 from coming off, and then permanent sealing is performed with the thermosetting resin 1823 . The sealing structure of the inspection hole 1821 may use a screw 1824 and a resin O-ring 1825 as shown in FIG. 10(b). In this case, the inspection hole 1821 is closed with the screw 1824 through the resin O-ring 1825 .

The formation position of the inspection hole 1821 in the upper lid portion 182 is desirably a position away from the optical path of the laser light output from the laser light source 11, as shown in FIG. Further, the upper lid portion 182 of this embodiment includes a space in which the inspection hole 1821 is formed and a partition wall portion 1826 that blocks the optical path space of the laser beam. This can prevent the inspection hole 1821 from adversely affecting the optical path space of the laser beam.

(Manufacturing method of backlight unit 1)
Next, a method for manufacturing the backlight unit 1 will be described with reference to FIG. 11 and the like. The manufacturing method of the backlight unit 1 includes steps 1 to 7, but it is possible to add other steps, omit some steps, or change the order of the steps.

In step 1, the window cover part 185 is mounted from the outside on the mounting part 1812 on the outer wall of the exit port 1811 of the outer case 18, and sealed and fixed with a thermosetting resin (not shown).

In step 2, the lower lid portion 183 is placed so as to cover the opening on the lower surface side of the outer case 18 from the outside, and is sealed and fixed with a thermosetting resin (not shown).

In process 3, the inner machine members (laser light source 11, wiring 12, collimator lens 13, dichroic mirror 14, heat sink 15, inner case 16, Peltier module 17) are accommodated in the accommodating portion 181 of the outer case 18.

In step 4, a thermosetting moisture absorbent (not shown) is applied to the inner wall of the upper lid portion 182 and cured by heating to fix the thermosetting moisture absorbent to the upper lid portion 182 . Since the thermosetting desiccant begins to absorb moisture immediately after curing is completed, it is preferable to fix the thermosetting desiccant to the parts to be assembled as soon as possible before the final sealing process of the outer case 18 . In that respect, the upper lid part 182 is the last part to be assembled, so it is suitable for fixing the thermosetting moisture absorbent, and suppresses the decrease in the moisture absorption capacity (total amount of moisture absorption) after fixing the thermosetting moisture absorbent. be able to. Conversely, a component such as the housing portion 181 that appears in the assembly from the beginning is not suitable for fixing the thermosetting moisture absorbent because the moisture absorbing ability deteriorates with time until the sealing is completed.

In step 5, the upper lid portion 182 is placed so as to cover the opening on the upper surface side of the outer case 18 from the outside, and is fixed with a thermosetting resin (not shown). After this step 5, the inspection hole 1821 formed in the upper lid portion 182 becomes the only ventilation hole.

In step 6, degassing is performed through the inspection hole 1821 formed in the upper lid portion 182, and the internal space S of the outer case 18 is brought into a negative pressure state. For example, an inspection device 500 (see FIG. 11) that inspects the airtightness of the outer case 18 through the inspection hole 1821 is used to put the internal space S of the housing portion 181 into a negative pressure state.

As shown in FIG. 11, the inspection apparatus 500 is provided with a work setting section 501 on which a work W (backlight unit 1) can be set, and on the work setting section 501 so as to be able to move up and down. The inspection device 500 includes a tubular inspection portion 502 , a vacuum pump 504 , a valve 505 , a regulator 506 , a barometer 507 and a power supply 508 . The inspection unit 502 can be airtightly connected to the inspection hole 1821 of the set work W. As shown in FIG. A vacuum pump 504 is connected to the inspection section 502 via an air flow path 503 . A valve 505 is interposed in the air flow path 503 to open and close the air flow path 503 . A regulator 506 is interposed in the air flow path 503 between the valve 505 and the vacuum pump 504 to adjust the vacuum pressure. A barometer 507 is connected to the air flow path 503 between the inspection unit 502 and the valve 505 to measure the air pressure inside the workpiece W. A power supply 508 is a power supply for the barometer 507 . Further, as indicated by dotted lines in FIG. 11, the space VS surrounding the workpiece W, the inspection unit 502, the valve 505, and the barometer 507 can be maintained in a vacuum or negative pressure state by degassing. In step 6 of the present embodiment, the space VS is brought into a negative pressure state so that the internal space S of the outer case 18 is brought into a negative pressure state, and the subsequent step 7 is also performed in the negative pressure space V. FIG.

In the airtightness inspection of the outer case 18 using the inspection device 500, the inspection unit 502 is airtightly connected to the inspection hole 1821 of the workpiece W set in the workpiece setting unit 501, and then the valve 505 is opened and the vacuum pump is operated. 504 is driven to evacuate the inside of the air flow path 503 and the internal space S of the workpiece W. After that, the numerical value of the barometer 507 is monitored with the valve 505 closed to determine the airtightness. In determining the airtightness, if the numerical value of the barometer 507 does not change, or if the number changes to the first decimal place, the airtightness is determined to be OK. In determining the airtightness, if the numerical value of the barometer 507 changes, the airtightness is NG.

The degree of negative pressure in the internal space S in step 6 is the upper lid portion 182, the lower lid portion 183, and the window cover portion 185 in any temperature range of the temperature range of actual use (-40 to 105 ° C. for in-vehicle use). It is preferable to maintain a negative pressure state (a state in which pressure is applied from the outside to the inside) even at the highest possible temperature so as not to come off. For example, it is preferable to create a negative pressure state even at a temperature (for example, 50° C.) higher than normal temperature (maximum 35° C.). The room temperature can be defined as, for example, 20°C ± 15°C (5 to 35°C) based on Japanese Industrial Standards (JIS Z 8703).

More preferably, it is preferable to create a negative pressure state at a temperature (for example, 80°C) higher than 70°C, the intermediate value between normal temperature (maximum 35°C) and maximum use temperature (here, 105°C). The maximum operating temperature can be defined as 105°C, which is the maximum temperature of -40°C to 105°C, assuming that the temperature range assumed for onboard instruments is -40°C to 105°C. More preferably, it is most preferable to have a negative pressure state at the maximum operating temperature (here, 105° C.).

In step 7, the inspection hole 1821 is closed in the negative pressure space V. In closing the inspection hole 1821, first, temporary sealing is performed with a photocurable resin 1822 to prevent the thermosetting resin 1823 from falling off, and then permanent sealing is performed with the thermosetting resin 1823 (see (a) in FIG. 10). )reference). Also, instead of the

curable resins

1822 and 1823, a sealing material such as a resin O-ring (torus-shaped rubber gasket) 1825 may be screwed into the inspection hole 1821 (see FIG. 10(b)). .

(Modification 1 of the manufacturing method of the backlight unit 1)
In the manufacturing method described above, the internal space S of the outer case 18 is a negative pressure space by performing the step 7 in the negative pressure space V. The internal space S of the outer case 18 may be a negative pressure space during actual use by performing Step 7 in a state of a high temperature (for example, 50 to 105° C.).

(Modification 2 of the manufacturing method of the backlight unit 1)
In the manufacturing method described above, the upper lid portion 182 has the inspection hole 1821, and the step of sealing the inspection hole 1821 (step 7) is the final step for sealing the internal space S of the outer case 18. When the upper lid portion 182 does not have the inspection hole 1821 and the step of sealing and fixing the upper lid portion 182 is the final step for sealing the internal space S of the outer case 18, the sealing and fixing of the upper lid portion 182 is performed. By performing the step of making the internal space S in a negative pressure state before the process, the backlight unit 1 in which the internal space S is in a negative pressure state can be manufactured.

Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope described in the claims. It is also possible to combine all or more of the constituent elements of the above-described embodiments.

H...Head-up display D...Image display S...Internal space V...Space W...Work 1...Backlight unit (illumination device)
11... Laser light source 11B... Blue laser light source (first laser light source)
11G ... green laser light source (second laser light source)
11R ... red laser light source (third laser light source)
REFERENCE SIGNS LIST 12 wiring 12B first wiring 12GR second wiring 13 collimator lens 13B first collimator lens 13G second collimator lens 13R third collimator lens 14 dichroic mirror 141 first dichroic mirror 142 second dichroic Mirror 15 Heat sink 151 First heat sink 1511 Heat radiation part 1512 Support part 152 Second heat sink 1521 Heat radiation part 1522 Support part 16 Inner case 161 Accommodating part 162 First entrance 163 Second entrance DESCRIPTION OF SYMBOLS 164... 3rd inlet 165... 1st outlet 166... 2nd outlet 167... 3rd outlet 17... Peltier module 18... Outer case 181... Accommodating part 1811... Outlet 1812... Mounting part 182... Upper cover part 1821 ... inspection hole 1822 ... photocurable resin 1823 ... thermosetting resin 1824 ... screw 1825 ... resin O-ring 1826 ... partition wall section 183 ... lower lid section 184 ... seal section 185 ... window cover section 2 ... rotary diffusion plate 3 ... lens DESCRIPTION OF SYMBOLS 4... Liquid crystal panel 500... Inspection apparatus 501... Work setting part 502... Inspection part 503... Air flow path 504... Vacuum pump 505... Valve 506... Regulator 507... Barometer 508... Power supply

Claims

a laser light source that outputs laser light;
a Peltier module for cooling the laser light source;
A lighting device comprising a case for sealing the laser light source and the Peltier module inside against moisture,
Said case is
a cylindrical accommodating portion formed with an emission port for emitting the laser light;
a first lid that is in thermal contact with the Peltier module and closes one opening of the housing;
a second lid portion that closes the other opening of the accommodating portion;
The lighting device, wherein a negative pressure space is formed in the accommodating portion.
The lighting device according to claim 1, wherein an inspection hole for inspecting the airtightness of the accommodating portion is formed in the second lid portion.
The lighting device according to claim 2, wherein the inspection hole is sealed with a sealing member after the inspection.
4. The lighting device according to claim 3, wherein a translucent window cover portion covering said exit port is fixed to the outer wall of said housing portion.
a heads-up display,
a lighting device according to any one of claims 1 to 4;
a lens for collimating illumination light output from the illumination device;
and a liquid crystal panel illuminated by illumination light that has passed through the lens.
A method for manufacturing a lighting device,
a housing step of housing the laser light source and the Peltier module in a housing portion of a case having an opening;
a negative pressure step in which the accommodating portion is placed in a negative pressure state;
and a sealing step of sealing the case.
7. The method of manufacturing a lighting device according to claim 6, wherein said negative pressure step brings said housing portion into said negative pressure state by setting said accommodating portion to a first temperature higher than normal temperature.