Vehicle display device

Abstract

To provide a vehicle display device which can inhibit temperature rise of a liquid crystal display element.SOLUTION: A vehicle display device 1 includes a housing 2, a thin film transistor (TFT) 3 housed in the housing 2, a mirror which is housed in the housing 2 and reflects display light Lt output from the TFT 3 toward a windshield of a vehicle; transparent plate-like sapphire glass 6 which is disposed contacting with a display surface 3a of the TFT 3; a lower case 21 configured to function as a heat radiation part which radiates heat; a heat pipe 7 in which one end 71 is connected to an edge part 61 of the sapphire glass 6 and the other end 72 is connected to the lower case 21 and which conducts heat of the sapphire glass 6 to the lower case 21.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a display device for a vehicle. [Background technology]

[0002] Conventionally, as a display device for a vehicle, for example, Patent Document 1 describes a liquid crystal display device that performs a desired display using liquid crystal. This liquid crystal display device includes a liquid crystal display element that performs liquid crystal display, a light source for illuminating the liquid crystal display element, an optical waveguide arranged on the back side of the liquid crystal display element and emitting light from the light source toward the liquid crystal display element, a wiring board provided with a liquid crystal drive circuit unit for driving the liquid crystal display element, a drive circuit that drives the light source on and off and serves as a heat source that generates heat, a heat dissipation member that dissipates the heat generated by the drive circuit, and a heat transfer member that connects the drive circuit and the heat dissipation member and is made of a member with a higher thermal conductivity than the heat dissipation member. In the liquid crystal display device, the heat dissipation member is separated from the drive circuit, and the heat dissipation member is connected to the drive circuit via the heat transfer member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-227072 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the liquid crystal display device described in the above-mentioned Patent Document 1 dissipates heat from the drive circuit that drives the light source using a heat dissipation member. However, it is desirable to dissipate heat from, for example, the liquid crystal display element to suppress a rise in temperature of the liquid crystal display element.

[0005] SUMMARY OF THE PRESENT DISCLOSURE The present invention has been made in view of the above, and has an object to provide a vehicle display device that can suppress a rise in temperature of a liquid crystal display element. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the vehicle display device of the present invention is characterized in that it comprises a housing, a liquid crystal display element housed in the housing, a mirror housed in the housing and reflecting display light output from the liquid crystal display element toward a transparent reflective member of the vehicle, a transparent plate-shaped heat conductive plate member arranged in contact with either the display surface or the back surface of the liquid crystal display element, a heat dissipation section that dissipates heat, and a heat pipe having one end connected to an edge of the heat conductive plate member and the other end connected to the heat dissipation section, and conducting heat from the heat conductive plate member to the heat dissipation section. Effect of the Invention

[0007] The vehicle display device according to the present invention can conduct heat from the liquid crystal display element to the heat dissipation portion via the heat conductive plate member and the heat pipe, thereby suppressing a rise in temperature of the liquid crystal display element. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a vehicle display device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of a connection of heat pipes according to the embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of a connection of heat pipes according to a first modified example of the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a connection of heat pipes according to a second modified example of the embodiment. [Diagram 5] FIG. 5 is a diagram showing the installation position of the thermistor according to the embodiment. [Figure 6] FIG. 6 is a diagram showing an example of how the thermistor is attached according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating heat conduction according to the embodiment. [Figure 8] FIG. 8 is a diagram showing an example of how the thermistor is attached according to a first modified example of the embodiment. [Figure 9] FIG. 9 is a diagram showing an example of mounting the thermistor according to a second modified example of the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of mounting the thermistor according to a third modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0010] 1, a vehicle display device 1 according to an embodiment is a head-up display mounted on a vehicle 100 such as an automobile, and displays a virtual image by reflecting display light Lt emitted toward a light-transmitting windshield 110 toward an eye point EP by the windshield 110. The vehicle display device 1 includes a housing 2, a TFT 3 as a liquid crystal display element, a backlight unit 4, a mirror 5, a sapphire glass 6 as a heat-conducting plate member, a heat pipe 7, and a transparent cover 10.

[0011] The housing 2 is accommodated under a dashboard 120 of the vehicle 100. The dashboard 120 has an opening 120a through which the display light Lt of the vehicle display device 1 passes. The opening 120a faces the windshield 110 in the vertical direction of the vehicle 100. The housing 2 is made of a light-blocking material. At least a part of the housing 2 is made of a material with high thermal conductivity such as metal. The housing 2 has a lower case 21 and an upper cover 22. The lower case 21 is a box-shaped member made of metal and opens upward in the vertical direction. The lower case 21 accommodates the TFT 3, the backlight unit 4, the mirror 5, the sapphire glass 6, and the heat pipe 7, and these components are fixed to the lower case 21. The upper cover 22 is attached to the lower case 21 and closes the opening 22a of the lower case 21. The upper cover 22 has an opening 22a through which light passes. The opening 22a is closed by a transparent cover 10 that transmits light.

[0012] The TFT3 is a display element having liquid crystal that displays an image. The TFT3 is, for example, a TFT-LCD (Thin Film Transistor-Liquid Crystal Display). The TFT3 is a film-like member including a liquid crystal layer, a glass electrode, a polarizing plate, and the like. The TFT3 is formed in a rectangular shape and has a display surface 3a (see FIG. 2) that outputs display light Lt. In the following description, the surface of the TFT3 opposite to the display surface 3a is referred to as a back surface 3b. The display surface 3a of the TFT3 is provided on the mirror 5 side, and the back surface 3b is provided on the backlight unit 4 side.

[0013] The backlight unit 4 irradiates light onto the rear surface 3b of the TFT 3. The backlight unit 4 has a light source 41 and a backlight case 42. The light source 41 has a plurality of light emitters. The light emitters are, for example, light emitting elements such as LEDs. The light source 41 is provided facing the rear surface 3b of the TFT 3, and irradiates light onto the rear surface 3b of the TFT 3. The backlight case 42 is formed of a light-shielding material, and houses the light source 41 and the like.

[0014] The mirror 5 is a mirror that reflects the display light Lt incident from the TFT 3 side toward the windshield 110 of the vehicle 100. The shape of the reflecting surface of the mirror 5 is, for example, a concave free-form surface. The reflecting surface of the mirror 5 is formed so as to enlarge the image formed by the display light Lt. The display light Lt reflected by the mirror 5 passes through the transparent cover 10 and enters the windshield 110. The windshield 110 reflects the display light Lt toward the eye point EP of the vehicle 100. The driver of the vehicle 100 visually recognizes a virtual image by the display light Lt reflected by the windshield 110.

[0015] The sapphire glass 6 is a transparent member that allows light to pass through the surface. The sapphire glass 6 is formed by artificially growing high-purity alumina (aluminum oxide) into a giant crystal, and has a thermal conductivity at least higher than that of air. The sapphire glass 6 is formed in a rectangular and flat shape, and is formed to be equal to or slightly larger than the size of the TFT 3. For example, as shown in FIG. 2, the sapphire glass 6 is formed to be slightly larger than the TFT 3, and a lower edge 61 of the sapphire glass 6 in the vertical direction protrudes more than a lower edge of the TFT 3 in the vertical direction. The edge 61 of the sapphire glass 6 is located outside the display area where the TFT 3 displays an image, and a heat pipe 7 described later is connected to the edge 61.

[0016] The sapphire glass 6 is arranged in contact with the display surface 3a of the TFT 3. The sapphire glass 6 is bonded to the display surface 3a of the TFT 3 by optical bonding such as OCA (Optical Clear Adhesive) or OCR (Optical Clear Resin), and is thus arranged in contact with the display surface 3a of the TFT 3. By bringing the sapphire glass 6 into contact with the display surface 3a of the TFT 3, the heat of the TFT 3 is easily conducted to the sapphire glass 6. It is desirable that the contact area of ​​the sapphire glass 6 with the TFT 3 is large. For example, the sapphire glass 6 is in contact with the entire display surface 3a of the TFT 3. It is desirable that the sapphire glass 6 covers the entire image display area of ​​the TFT 3. This allows the sapphire glass 6 to suppress stress from being applied to a local portion of the TFT 3, and suppresses the whitening phenomenon. The thickness of the sapphire glass 6 may be greater than the thickness of the TFT 3. The sapphire glass 6 in contact with the TFT 3 can increase the heat capacity of the TFT 3 and absorb the heat generated by the TFT 3 .

[0017] The heat pipe 7 transfers (transports) the heat of the sapphire glass 6 to the heat dissipation section. The heat pipe 7 is formed in a long shape, and a connection section 73 provided at one end 71 is connected to the heat source, and the other end 72 is connected to the heat dissipation section (low temperature section). The working fluid evaporates and becomes gas due to the heat of the heat source, and absorbs the heat as latent heat and moves to the low temperature section of the pipe. Then, the working fluid that has moved to the low temperature section of the heat pipe 7 condenses, releases heat, and returns to liquid. In this way, the heat pipe 7 efficiently transfers the heat of the heat source to the heat dissipation section. The heat pipe 7 has a high thermal conductivity, and although it depends on the bending method, the thermal conductivity is about 10000 W / m·K to about 20000 W / m·K at Φ6 mm, which is overwhelmingly higher than aluminum and the like. In the embodiment, the heat pipe 7 has a connection section 73 at one end 71 connected to the sapphire glass 6, and the other end 72 connected to the lower case 21 made of metal. For example, a connection portion 73 of one end 71 of the heat pipe 7 is connected to a vertically lower edge portion 61 of the sapphire glass 6 via an adhesive 74a, and the other end 72 is connected to a vertically lower bottom surface 21a of the metal lower case 21 via an adhesive 74b. The heat pipe 7 conducts the heat of the sapphire glass 6 that has absorbed the heat generated by the TFT 3 to the metal lower case 21. As a result, the vehicle display device 1 can dissipate the heat generated by the TFT 3 through the metal lower case 21, thereby suppressing an increase in the temperature of the TFT 3.

[0018] As described above, the vehicle display device 1 according to the embodiment includes a housing 2, a TFT 3 housed in the housing 2, a mirror 5 housed in the housing 2 and reflecting display light Lt output from the TFT 3 toward the windshield 110 of the vehicle, a transparent plate-shaped sapphire glass 6 arranged in contact with the display surface 3a of the TFT 3, a lower case 21 functioning as a heat sink for dissipating heat, and a heat pipe 7 having one end 71 connected to the edge portion 61 of the sapphire glass 6 and the other end 72 connected to the lower case 21 and conducting heat from the sapphire glass 6 to the lower case 21.

[0019] With this configuration, the vehicle display device 1 can conduct the heat of the TFT 3 to the lower case 21 through the sapphire glass 6 and the heat pipe 7, so that the temperature rise of the TFT 3 can be suppressed. In addition, since the vehicle display device 1 connects one end 71 of the heat pipe 7 to the edge portion 61 of the sapphire glass 6, for example, the whitening phenomenon caused by connecting one end 71 of the heat pipe 7 to the edge portion of the TFT 3 can be prevented. Since the vehicle display device 1 conducts heat to the lower case 21 through the heat pipe 7 having a relatively small cross-sectional area, the size of the housing 2 can be suppressed compared to the case where heat is dissipated using a heat sink, for example. Since the vehicle display device 1 can reduce the size of the expensive sapphire glass 6 compared to the case where the sapphire glass 6 is extended to the lower case 21 and the sapphire glass 6 is directly connected to the lower case 21, the cost can be reduced.

[0020] In the vehicle display device 1, the housing 2 is made of metal and functions as a heat dissipation section. The other end 72 of the heat pipe 7 is connected to the metal housing 2. With this configuration, the vehicle display device 1 can dissipate heat without using a separate heat sink or the like as a heat dissipation section, thereby suppressing an increase in the number of parts.

[0021] Next, modified examples of the embodiment will be described. In the modified examples, the same components as those in the embodiment will be given the same reference numerals, and detailed description thereof will be omitted. FIG. 3 is a diagram showing a connection example of a heat pipe 7 of a vehicle display device 1A according to a first modified example of the embodiment. The vehicle display device 1A shown in FIG. 3 differs from the vehicle display device 1 according to the embodiment in that it has a heat-conducting frame member 8.

[0022] As shown in FIG. 3, the heat conduction frame member 8 is provided extending in the extension direction along the edge portion 61 of the sapphire glass 6, and the cross section in the cross direction intersecting the extension direction is formed in a frame shape. The heat conduction frame member 8 is, for example, formed of a metal with a relatively high thermal conductivity, and is an elongated member extending from one side to the other in the width direction of the sapphire glass 6. The heat conduction frame member 8 is fitted into the edge portion 61 of the sapphire glass 6 and fixed to the edge portion 61 via an adhesive 74a. In a state where the heat conduction frame member 8 is fixed to the edge portion 61 of the sapphire glass 6, the heat conduction frame member 8 holds the edge portion 61 by sandwiching it from both sides, and contacts both sides of the edge portion 61. That is, the heat conduction frame member 8 contacts both sides of the edge portion 61 of the sapphire glass 6, the first surface 6a on the TFT3 side and the second surface 6b on the opposite side to the TFT3 side. One end 71 of the heat pipe 7 is connected to the heat conduction frame member 8 via an adhesive 74c. The other end 72 of the heat pipe 7 is inserted and fixed in an insertion portion 21e provided in the lower case 21. The insertion portion 21e includes a bottom surface 21a of the lower case 21, a side wall 21b erected from the bottom surface 21a, and an upper wall 21c extending from an upper portion of the side wall 21b along the bottom surface 21a of the lower case 21 and forming an insertion space 21d between the bottom surface 21a and the upper wall 21c. The other end 72 of the heat pipe 7 is inserted into the insertion space 21d between the bottom surface 21a and the upper wall 21c of the lower case 21 and press-fitted and fixed in the insertion portion 21e.

[0023] As described above, the vehicle display device 1A includes a heat conductive frame member 8 that is provided along the edge 61 of the sapphire glass 6, sandwiches and holds the edge 61 from both sides, and is in contact with both sides of the edge 61. One end 71 of the heat pipe 7 is connected to the edge 61 of the sapphire glass 6 via the heat conductive frame member 8. With this configuration, the vehicle display device 1A can conduct heat from both sides of the sapphire glass 6 to the heat pipe 7, thereby improving the efficiency of heat conduction and thereby further suppressing the temperature rise of the TFT 3.

[0024] Furthermore, in the vehicle display device 1A, the other end 72 of the heat pipe 7 is inserted into the insertion portion 21e of the lower case 21 and fixed thereto, so that the heat pipe 7 can be easily attached to the lower case 21, improving workability.

[0025] 4 is a diagram showing a connection example of a heat pipe 7 of a vehicle display device 1B according to a second modified example of the embodiment. The vehicle display device 1B shown in FIG. 4 differs from the vehicle display device 1 according to the embodiment in that it has Peltier elements 77 and 78.

[0026] The Peltier element 77 has a heat absorbing surface 77a that absorbs heat and a heat dissipating surface 77b that dissipates the absorbed heat depending on the direction of current flow. The Peltier element 77 is provided between the edge 61 of the sapphire glass 6 and the heat conducting frame member 8, with the heat absorbing surface 77a in contact with the sapphire glass 6 and the heat dissipating surface 77b in contact with the heat conducting frame member 8. The Peltier element 77 transfers the heat from the sapphire glass 6 to the heat conducting frame member 8.

[0027] The Peltier element 78 has a heat absorbing surface 78a that absorbs heat and a heat dissipating surface 78b that dissipates the absorbed heat depending on the direction of the current flow. The Peltier element 78 is provided between the other end 72 of the heat pipe 7 and the bottom surface 21a of the lower case 21, with the heat absorbing surface 78a in contact with the other end 72 of the heat pipe 7 and the heat dissipating surface 78b in contact with the bottom surface 21a of the lower case 21. The Peltier element 78 transfers heat from the other end 72 of the heat pipe 7 to the bottom surface 21a of the lower case 21.

[0028] As described above, the vehicle display device 1B is equipped with Peltier elements 77, 78, and the Peltier element 77 transfers heat from the sapphire glass 6 to the thermally conductive frame member 8, and the Peltier element 78 transfers heat from the heat pipe 7 to the lower case 21. Therefore, the heat of the TFT 3 can be efficiently conducted to the lower case 21 via the sapphire glass 6 and the heat pipe 7, thereby further suppressing the temperature rise of the TFT 3.

[0029] Next, an example of the installation of the thermistor 9 for detecting the temperature of the TFT 3 will be described. The vehicle display device 1C includes a thermistor 9 as a temperature sensor, as shown in FIG. 5 and FIG. 6. The thermistor 9 is provided on the sapphire glass 6, as shown in FIG. 5, and the temperature detection position S is located at the edge 61 of the sapphire glass 6 and is located outside the display area R where the TFT 3 displays an image. The thermistor 9 is located at the center in the width direction at the edge 61 of the sapphire glass 6. In the vehicle display device 1C, for example, as shown in FIG. 6, the sapphire glass 6 is arranged in contact with the back surface 3b of the TFT 3. That is, in the vehicle display device 1C, the sapphire glass 6 is provided between the TFT 3 and the backlight case 42. In the vehicle display device 1C, an aluminum substrate BP is provided between the sapphire glass 6 and the backlight case 42. The thermistor 9 is mounted on the aluminum substrate BP, and the thermistor 9 is arranged in contact with the sapphire glass 6 via the thermal sheet T. A control unit M is connected to the thermistor 9 via a wiring W. The control unit M controls the light source 41 of the backlight unit 4 and the angle of the mirror 5 based on the temperature detected by the thermistor 9. For example, when the temperature detected by the thermistor 9 is equal to or higher than a predetermined reference temperature, the control unit M relatively reduces the luminance of the light source 41 of the backlight unit 4. When the temperature detected by the thermistor 9 is equal to or higher than the reference temperature, the control unit M may control the angle of the mirror 5 so that external light does not enter the TFT 3 through the mirror 5. In addition, in the vehicle display device 1C, a resin bezel B is provided on the edge of the TFT 3 via a packing P.

[0030] In a conventional vehicle display device, the thermistor is disposed in contact with blue plate glass or white plate glass provided on the TFT, and therefore there is a delay before the heat of the TFT is conducted to the thermistor via the blue plate glass or white plate glass. In the vehicle display device 1C according to the embodiment, the thermistor 9 is disposed in contact with the sapphire glass 6 provided on the TFT 3, and therefore the heat of the TFT 3 is quickly conducted to the thermistor 9 via the sapphire glass 6. This is because while ordinary blue plate glass or white plate glass has a thermal conductivity of approximately 1 W / m·K, the thermal conductivity of the sapphire glass 6 is approximately 40 W / m·K. 7, in a light distribution D in which external light is concentrated at the center of the TFT 3, if the sapphire glass 6 is not provided on the TFT 3, the temperature distribution of the TFT 3 becomes a temperature distribution G1 in which the center of the TFT 3 becomes hot, whereas if the sapphire glass 6 is provided on the TFT 3, the temperature distribution becomes a temperature distribution G2 in which the entire TFT 3 becomes the same temperature as a result of the heat of the TFT 3 being conducted to the sapphire glass 6. As a result, since the sapphire glass 6 is provided on the TFT 3, the vehicle display device 1C can suppress a rise in the temperature of the TFT 3, and can accurately detect the temperature of the TFT 3 by the thermistor 9 arranged in contact with the sapphire glass 6, thereby enabling a process of suppressing a rise in the temperature of the TFT 3 to be performed at an appropriate timing.

[0031] Fig. 8 is a diagram showing an example of attachment of thermistor 9 according to a first modified example of the embodiment. The thermistor 9 shown in Fig. 8 is provided between the sapphire glass 6 and the backlight case 42, and is arranged in contact with the sapphire glass 6 via adhesive 74d while being accommodated in a recess of the backlight case 42.

[0032] Fig. 9 is a diagram showing an example of attachment of a thermistor 9 according to a second modified example of the embodiment. The thermistor 9 shown in Fig. 9 is provided on a flexible printed circuit (FPC) F, and is located between the sapphire glass 6 and the backlight case 42, and is arranged in contact with the sapphire glass 6 via a thermal sheet T.

[0033] Fig. 10 is a diagram showing an example of attachment of thermistor 9 according to a third modified example of the embodiment. The thermistor 9 shown in Fig. 10 is provided on a flexible substrate F, and is located between the sapphire glass 6 and the backlight case 42, and is arranged in contact with the sapphire glass 6 via an adhesive 74d.

[0034] In the above description, the heat-conducting plate member is an example of sapphire glass 6, but the heat-conducting plate member is not limited to this, and may be any other transparent heat-conducting member.

[0035] Although an example has been described in which the heat dissipation portion is the metallic lower case 21, the present invention is not limited to this, and for example, a heat sink may be provided separately.

[0036] The adhesives 74a, 74b, 74c, and 74d have a relatively high thermal conductivity, and may be substituted with, for example, a thermal sheet.

[0037] Although an example has been described in which the heat pipe 7 is connected to the lower vertical edge 61 of the sapphire glass 6, this is not limited to this, and the heat pipe 7 may be connected to, for example, the upper vertical edge of the sapphire glass 6, or a widthwise edge of the sapphire glass 6 that intersects with the vertical direction.

[0038] Although the sapphire glass 6 is arranged in contact with the TFT 3 by optical bonding such as OCA or OCR in the above example, the present invention is not limited to this, and the sapphire glass 6 may be arranged in contact with the TFT 3 by other methods. [Explanation of symbols]

[0039] 1, 1A, 1B, 1C: Vehicle display device 2: Housing, 3: TFT (liquid crystal display element), 3a: Display surface, 3b: Rear surface 4: Backlight unit, 5: Mirror, 6: Sapphire glass (heat conductive plate material) 7: heat pipe, 8: heat conductive frame member, 9: thermistor (temperature sensor) 10: Transparent cover 21: Lower case (heat dissipation section), 21a: Bottom surface, 22: Upper cover 41: Light source, 42: Backlight case 61: Edge 71: one end, 72: other end, 73: connection portion, 74a to 74d: adhesive, 77, 78: Peltier element 100: vehicle, 110: windshield (transparent reflective material), 120: dashboard EP: Eye point, Lt: Display light

Claims

1. A housing and A liquid crystal display element housed in the housing; a mirror housed in the housing and configured to reflect display light output from the liquid crystal display element toward a transparent reflective member of the vehicle; a transparent, plate-like heat-conducting plate member arranged in contact with either a display surface or a rear surface of the liquid crystal display element; A heat dissipation unit that dissipates heat; a heat pipe having one end connected to an edge of the thermally conductive plate member and the other end connected to the heat dissipation portion, for conducting heat from the thermally conductive plate member to the heat dissipation portion.

2. a heat conduction frame member provided along the edge of the heat conduction plate member, sandwiching and holding the edge from both sides and contacting both sides of the edge, The display device for a vehicle according to claim 1 , wherein the one end of the heat pipe is connected to the edge portion via the thermally conductive frame member.

3. the housing is made of metal and functions as the heat dissipation portion; The display device for a vehicle according to claim 1 , wherein the other end of the heat pipe is connected to the metallic housing.

4. Further comprising a temperature sensor for detecting a temperature, The heat conductive plate member is made of sapphire glass, The display device for a vehicle according to claim 1 or 2, wherein the temperature sensor has a temperature detection position located at the edge of the thermally conductive plate member.

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