JP2017142882A - Light source device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit temperature rise of a laser diode in a light source device using a laser light source and an image display device using the light source device.SOLUTION: A light source device includes: a laser diode which emits a laser beam; an LD holder 600 to which the laser diode is attached; and an optical base part 500 connected with the LD holder 600 with screws. Multiple protrusion parts are formed on a back surface of the optical base part 500 between the LD holder 600 and the optical base part 500, and the protrusion parts allow the LD holder 600 to contact with the optical base part 500. A cooling unit 400 (a heat sink 401, a peltier element 402, heat radiation fins 403) is attached to the LD holder 600.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a light source device and an image display device using the light source device, and is suitable for, for example, a light source device using a laser light source and an image display device for displaying an image formed by an image forming unit using the light source device. is there.

  Laser display devices that project images onto the screen using laser light such as red, blue, and green, and recently, surface reflection (or half mirror) on glass surfaces and free-form surface mirrors Development of an image display device that displays an image in a space by using a virtual image optical system in combination with the above has progressed.

  In particular, application to an image display device called a head-up display mounted on a moving body such as a passenger car is expected. For example, in a head-up display mounted on a passenger car, light modulated by image information is projected toward a windshield (front glass), and the reflected light is irradiated to the eyes of the driver.

  As a result, the driver can see a virtual image of the image in front of the windshield. For example, the vehicle speed, temperature, etc. are displayed as a virtual image. Recently, it has been considered to display a navigation image or an image that alerts a driver of a real passerby as a virtual image.

  In the head-up display, a laser light source such as a semiconductor laser can be used as a light source. In this configuration, the laser beam scans the screen while the laser beam is modulated in accordance with the video signal. On the screen, the laser light is diffused and the area of the light irradiated to the driver's eyes is expanded. As a result, even if the driver moves his head to some extent, the eyes do not come out of the irradiation area, and the driver can see the image (virtual image) well and stably.

  By using a laser light source, the optical system that scans the laser beam on the screen can be miniaturized, and in combination with a virtual image optical system having a large optical magnification, a large virtual image can be displayed despite the smaller body size. Therefore, the effect of increasing the number of models equipped with a head-up display is expected.

  The following Patent Document 1 includes a laser diode 11a (11b or 11c) in a head-up display device 100 (projector) including laser diodes 11a to 11c, a housing portion 7 (base portion 7), and heat sinks 5a and 5b. ) To the housing portion 7, a configuration in which the thermal resistance of the first heat transfer path is larger than the heat resistance of the second heat transfer path from the laser diode 11 a (11 b or 11 c) to the heat sink 5 a or 5 b is disclosed. Yes.

JP-A-2015-194705

  In Patent Document 1, as shown in FIG. 13, the mounting base portion 71 a is formed of a resin having low thermal conductivity or the like. An LD plate 8a made of a metal such as aluminum (or a resin having higher thermal conductivity than a general resin) is disposed on the back side of the laser diode 11a, and heat is transferred from the back surface of the laser diode 11a to the heat sink 5a side. It is provided for heat transfer. For this reason, as described above, the thermal resistance from the laser diode 11a to the housing portion 7 is larger than the thermal resistance from the laser diode 11a to the heat sink 5a or 5b.

  However, a head-up display mounted on a passenger car or the like must pass an operation test under a high-temperature environment of, for example, 80 degrees, but it is a combination of a resin mounting base and an LD plate made of metal such as aluminum. In this case, the thermal expansion coefficients of the respective materials are different, which causes distortion and deformation, resulting in a problem that the optical adjustment is shifted.

  Also, if it is composed of a mounting base made of a resin having low thermal conductivity and an LD plate made of a resin having higher thermal conductivity than a general resin, it will be deformed in a high temperature environment as described above. There is a risk that the optical adjustment that has been adjusted in the manufacturing stage may be shifted, or that the mounting base and the LD plate itself may be damaged.

  If the heat transfer path from the laser diode to the heat sink has another structure such as a housing, or if another structure or part of it is used as the heat transfer path, the heat from the outside air to the laser diode Since the resistance is reduced and the heat transfer path is heated from the outside air, a larger cooling capacity is required.

  In order to solve the above-described problems, a light source device of the present invention includes a light source that emits laser light, a light source holding unit to which the light source is attached, and a base unit that is connected to the light source holding unit. A convex portion is formed on at least one of the light source holding portion and the base portion between the holding portion and the base portion, and the light source holding portion and the base portion are in contact with each other by the convex portion. It is characterized by that.

  An image display device according to the present invention includes the light source device.

  According to the image display device of the present invention, the convex portion is formed on either the light source holding portion or the base portion, and the light source holding portion and the base portion are in contact with each other by the convex portion. It is possible to suppress the heat from the pedestal from being transmitted to the light source holding unit and the temperature of the light source from rising.

FIG. 1A and FIG. 1B are diagrams illustrating a usage pattern of the image display device according to the embodiment. FIG. 2 is a diagram illustrating a schematic configuration of the image display apparatus according to the embodiment. FIG. 3 is a schematic diagram illustrating a schematic configuration of the optical module (light source device) according to the embodiment. FIG. 4 is a perspective view showing an appearance of the optical module (light source device) according to the embodiment. FIG. 5 is a perspective view showing an appearance of the optical module (light source device) according to the embodiment. FIG. 6 is a perspective view showing a state where the shield cover of the optical module (light source device) according to the embodiment is deleted. FIG. 7 is a perspective view showing a state where the shield cover of the optical module (light source device) according to the embodiment is deleted. FIG. 8 is a perspective view showing an appearance of the optical base portion in the optical module (light source device) according to the embodiment. FIG. 9 is a perspective view showing an appearance of the optical base portion in the optical module (light source device) according to the embodiment. FIG. 10A and FIG. 10B are perspective views showing the appearance of the LD holder in the optical module (light source device) according to the embodiment. FIG. 11A and FIG. 11B are perspective views showing the appearance of a heat sink in the optical module (light source device) according to the embodiment. FIG. 12 is a perspective view showing an appearance of a heat radiation fin in the optical module (light source device) according to the embodiment. FIG. 13 is a cross-sectional view of a main part showing a configuration of a conventional head-up display device.

  Hereinafter, a light source device and an image display device according to embodiments of the present invention will be described with reference to the drawings.

  First, FIG. 1 is a diagram showing a usage pattern of a light source device and an image display device 120 having the light source device according to an embodiment of the present invention.

  FIG. 1A is a perspective view of the inside of the vehicle 101 from the side of the vehicle 101, and FIG. 1B is a view of the front of the traveling direction from the inside of the vehicle 101. In the present embodiment, as an example, an in-vehicle head-up display device is applied as the light source device.

  As shown in FIG. 1A, the image display device 120 is installed inside the dashboard 111 of the vehicle 101. As shown in FIG. 1A and FIG. 1B, the image display device 120 applies the laser light modulated by the video signal to the projection region 113 disposed near the driver seat below the windshield 112. Project.

  The laser light is reflected by the projection area 113 and is irradiated to a horizontally long area (eye box area) around the eye position of the driver 102. Thus, the predetermined image 130 is displayed as a virtual image in the field of view ahead of the driver 102.

  The driver 102 can superimpose an image 130 that is a virtual image on the scenery in front of the windshield 112. That is, the image display device 120 forms an image 130 that is a virtual image in a space in front of the projection area 113 of the windshield 112.

  Next, FIG. 2 is a schematic diagram showing an internal configuration of the image display device 120. As shown in FIG. 2, the image display device 120 includes an optical module 121 (light source device) and a virtual image optical system 122.

  Further, FIG. 3 is a schematic diagram showing an internal configuration of the optical module 121. The optical module 121 includes LD 201, LD 202, and LD 203 which are laser diodes (hereinafter referred to as LDs) as light sources, and emits laser light modulated by a video signal (not shown). In the present invention, the LD 201 is a blue semiconductor laser light source, the LD 202 is a green semiconductor laser light source, and the LD 203 is a red semiconductor laser light source.

  Laser light emitted from each LD is shaped as a substantially coaxial laser beam via the first dichroic mirror 210, the second dichroic mirror 211, and the third dichroic mirror 212, and is incident on the scanning unit 213. Thereafter, the laser beam is guided to the virtual image optical system 122 shown in FIG. 2 through a scanning mirror 213a and a screen driving unit 213b for three-dimensional display in the scanning unit 213.

  In FIG. 3, 204 is a first collimator module, 205 is a second collimator module, 206 is a third collimator module, 207 is a first shift module, 208 is a second shift module, and 209 is a third shift module. is there.

  Next, reference numeral 214 denotes a spectroscopic mirror that passes about 95% of the laser light from each LD and reflects about 5%. The reflected laser beam of about 5% is guided to the luminance monitor 215 ahead of the laser beam and used for luminance adjustment or the like in the image display device.

  The scanning mirror 213a has an axis that reciprocates at a resonance frequency of about 20 kHz (referred to as a high speed axis for convenience) and an axis that reciprocates at an image frame rate (60 Hz in the embodiment) (for convenience, a low speed axis). Have two rotation axes.

  Returning to FIG. 2, the virtual image optical system 122 includes a curved reflection surface 122 a and a planar reflection surface 122 b. Laser light emitted from the optical module 121 is reflected by the virtual image optical system 122 toward the windshield 112. The laser light reflected by the windshield 112 is applied to the eyes 102a of the driver 102. The optical system of the optical module 121 and the virtual image optical system 122 are set so that the virtual image 130 is displayed in a predetermined size in front of the windshield 112.

  In this embodiment, the example in the case of developing to a windshield type head-up display that observes a virtual image through a windshield has been described, but a head-up type called a combiner type that observes a virtual image through an optical component called a combiner. It can also be expanded to a display.

  In this embodiment, the scanning mirror 213a has an optical configuration using a reciprocating mirror using a so-called MEMS structure using an effect of applying distortion by a piezoelectric material, an electromagnetic force, or static electricity. As long as the laser beam is scanned, a polygon mirror or a galvanometer mirror can be used.

  Next, FIGS. 4 and 5 show the appearance of the optical module 121. 4 is a perspective view of the optical module as seen from the front, and FIG. 5 is a perspective view of the optical module as seen from the back.

  In each figure, 300 is a shield cover, and a projection window 300a for projecting laser light is formed on a part of the shield cover. Reference numeral 400 denotes a cooling unit (cooling unit) for radiating heat generated in the optical module 121. The cooling unit 400 includes a heat sink 401, a Peltier element 402, and heat radiating fins 403. Reference numeral 404 denotes an insulator as a heat insulating material for the purpose of preventing heat absorption from outside air, and is bonded to the surface of the heat sink 401.

  FIG. 6 is a perspective view showing the inside of the optical module 121, and shows a state in which the shield cover 300 is deleted from FIG. 3, reference numeral 500 denotes an optical base portion (base portion) on which a portion surrounded by a broken-line rectangle in FIG. 3 is mounted, 501 denotes a scanning base portion on which a scanning portion 213 is mounted, and 502 denotes the optical base portion. 500 and a scanning base portion 501 are combined base portions.

  FIG. 7 is a view of the optical module 121 shown in FIG. 6 as viewed from the back, and shows a state where the cooling unit 400 is omitted. In the figure, reference numeral 600 denotes an LD holder (light source holding unit), which is attached to the back side of the optical base unit 500. As shown in the figure, LD 201, LD 202, and LD 203, which are laser diodes as light sources, are attached to LD holder 500. In the figure, the flexible substrate to which the terminals of LD201, LD202, and LD203 are electrically connected is omitted.

  Also, in the same figure, there is a slight gap between the side surface of the LD holder 600 (closer to the scanning unit 213) and the optical base unit 500 (P in the figure), and further, the bottom surface of the LD holder 600 and the optical base. There is also a slight gap between the upper surface of the portion 500 (Q in the figure) and it is configured not to contact. Therefore, consideration is given so that the heat of the optical base unit 500 is not easily transmitted from the side surface of the LD holder 600 or the bottom surface of the LD holder 600.

  8 and 9 are perspective views showing the appearance of the optical base unit 500. FIG. 8 is a view of the optical base unit 500 viewed from the back, and FIG. 9 is a view of the optical base unit 500 viewed from the front. FIG.

  The optical base unit 500 is made of aluminum die casting. In each figure, reference numeral 500a denotes a columnar part formed integrally with the optical base unit 500, and a screw hole 500b for attaching the LD holder 600 is formed in the columnar part 500a. Further, a convex portion 500c having a trapezoidal cross section is formed on the back surface and the columnar portion 500a of the optical base portion 500, and the LD holder 600 is attached to the optical base portion 500 at the tip of the convex portion 500c. Mounted to contact. Reference numeral 500d denotes a positioning pin for positioning the LD holder 600.

  Thus, in the present embodiment, a material having a large thermal resistance such as air is provided between the LD holder 600 as the light source holding part and the optical base 500 as the base part by providing the convex part 500c. The area where there exists.

  In the above description, the convex portion 500c has a trapezoidal cone shape in cross section. However, the present invention is not limited thereto, and various forms such as a pyramid having a trapezoidal shape in a cross section, a cone, and a hemisphere shape are possible. The number can also be changed as appropriate.

  10 (a) and 10 (b) are perspective views showing the appearance of the LD holder 600. FIG. 10 (a) is a view of the LD holder 600 as viewed from the front, and FIG. b) is a view of the LD holder 600 viewed from the back.

  The LD holder 600 is made of a material having high thermal conductivity. For example, copper or copper alloy is suitable. In each figure, 600a is an LD mounting hole formed for mounting the three LDs, and 600b is a heat sink mounting hole for mounting the heat sink 400. Reference numerals 600 c and 600 d denote attachment holes for screws for attaching the LD holder 600 to the optical base unit 500, and are formed at positions corresponding to the screw holes 500 b of the optical base unit 500.

  Reference numerals 600e and 600f denote positioning holes into which the positioning pins 500d of the optical base unit 500 are inserted. The positioning hole 600e is a circular hole, but the positioning hole 600f is a long hole.

  Reference numeral 600g denotes an adjustment screw hole for attaching an adjustment screw (not shown) for adjusting the focus of the first collimator unit 204, the second collimator unit 205, and the third collimator unit 206 shown in FIG. is there.

  It should be noted that soldering is performed to fill a slight gap between each LD and the inner surface of the LD mounting hole 600a, so that heat generated in each LD is reliably transmitted to the LD holder 600.

  FIG. 11A and FIG. 11B are perspective views showing the appearance of the heat sink 401, and FIG. 11A is a view as seen from the surface side where the heat sink 401 contacts the back surface of the LD holder 600. FIG. 11B is a view of the heat sink 401 as seen from the opposite side of FIG. 11A.

  The heat sink 401 is made of copper (a copper alloy may be used). As shown in each figure, the heat sink 401 is formed with a plurality of screw holes 401 a for attaching the heat sink 401 to the LD holder 600 and a plurality of screw holes 401 b for connecting the heat sink 401 and the radiation fins 403.

  Next, FIG. 12 is a perspective view showing an appearance of the heat radiating fin 403. The heat radiation fin 403 is made of aluminum die casting. As shown in the figure, screw holes 403a are formed in the heat dissipating fins 403.

  A Peltier element 402 is disposed between the heat sink 401 and the heat radiation fin 403, and the heat sink 401 and the heat radiation fin 403 are coupled with screws. As a result, the Peltier element 402 is sandwiched and fixed between the heat sink 401 and the radiation fin 403 (see FIGS. 4 to 6).

  The guaranteed operating temperature of the LD 201 (blue laser diode), LD 202 (green laser diode), and LD 204 (red laser diode) used in this embodiment is about 65 ° C., but depending on the manufacturer, the operation guaranteed Some laser diodes have a temperature of 85 ° C. (Each laser diode has a problem that its brightness decreases as the temperature increases, although it does not break if it is within the guaranteed operating temperature).

  In the present embodiment, the LD holder 600 and the optical base unit 500 are coupled by screws, but the back surface of the optical base unit 500 and the front surface of the LD holder 600 are formed on the back surface of the optical base unit 500. Contact at the shaped portion 500c. That is, since it is configured to contact with a small area at the tips of the plurality of convex portions 500c, the heat of the optical base portion 500 is transmitted to the LD holder, and the temperature of each LD rises and the brightness decreases. , Can be prevented from being destroyed.

  Subsequently, when the convex portion 500c is eliminated from the back surface of the optical base portion 500, and the back surface of the optical base portion 500 and the front surface of the LD holder 600 are in contact with each other over a wide area, as in the present embodiment, A result of comparison between the back surface of the optical base unit 500 and the front surface of the LD holder 600 compared to a configuration in which the plurality of convex portions 500c are in contact with each other at a very small area will be described.

  When the optical module 121 is operated in a high temperature environment of 85 ° C., the temperature of the optical base is reduced by about 11 ° C. from the outside air temperature and the temperature of the LD holder 600 is about the outside air temperature without the convex portion 500c. It decreased by 12 ° C. The temperature drop of LD with respect to the outside temperature stopped at about 11 ° C. On the other hand, in the case where the convex portion 500c is provided, the temperature drop with respect to the outside air temperature is stopped at about 5 ° C. on the optical base, so that the temperature drop of the LD holder 600 is 26 ° C., and the temperature drop of the LD is about 23 ° C. The cooling efficiency was improved.

  As described above, when there is no convex portion 500c, a large amount of heat is transferred from the optical base portion 500 to the LD holder 600, and even if the cooling unit 400 dissipates heat, the temperatures of the LD holder 600 and LD are high. It has risen to near ambient temperature. On the other hand, when the convex portion 500c is provided, heat transfer from the optical base portion 500 to the LD holder 600 is suppressed, and the temperatures of the LD holder 600 and LD can be maintained at a temperature much lower than the environmental temperature. all right.

  Further, in the above description, the back surface of the optical base unit 500 and the front surface of the LD holder 600 are configured to contact each other at a minute area at the tips of the plurality of convex portions 500c. A heat insulating material may be sandwiched between the front surface of the holder 600. However, since an accuracy system is required for the light emitting point position of the LD and the inclination of the optical axis of the LD, a heat insulating member having a hole in the portion where the convex portion 500c is located, and the like between the convex portion 500c and the LD holder 600. It is desirable to prevent other members from being pinched.

  The configuration described in the above embodiment is merely an example, and it is needless to say that the configuration other than the modes illustrated in the description and the drawings can be appropriately described.

  The present invention can be applied to a light source device using a laser light source and an image display device using the same.

DESCRIPTION OF SYMBOLS 120 ... Image display apparatus 121 ... Optical module (light source device)
201 ... LD (laser diode for blue)
202 ... LD (green laser diode)
203 ... LD (red laser diode)
204 ... 1st collimator module 205 ... 2nd collimator module 206 ... 3rd collimator module 207 ... 1st shift module 208 ... 2nd shift module 209 ... 3rd shift module 210 ... 1st dichroic mirror 211 ... 2nd dichroic mirror 212 ... Third dichroic mirror 400 ... Cooling unit (cooling section)
401 ... Heat sink 402 ... Peltier element 403 ... Radiation fin 500 ... Optical base (base)
500c ... Convex part 600 ... LD holder (light source holding part)

Claims (6)

A light source that emits laser light;
A light source holder to which the light source is attached;
A base part connected to the light source holding part,
A convex portion is formed on at least one of the light source holding portion and the base portion between the light source holding portion and the base portion, and the light source holding portion and the base portion are in contact with each other by the convex portion. A light source device. The light source device according to claim 1,
A light source device, further comprising a cooling unit attached to the light source holding unit. In the light source device according to claim 1 and claim 2,
The light source holding section and the base section are made of metal. In the light source device according to claim 1 to claim 3,
A light source device, wherein the light source comprises a laser diode. In the light source device according to claim 1 to claim 4,
A light source device, wherein a mechanism for optically adjusting laser light from the light source is mounted on the base portion.   An image display device comprising the light source device according to claim 1.

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