Vehicle display device

Abstract

To provide a display device for a vehicle capable of suitably detecting a rise in the temperature of a liquid crystal display element due to sunlight.SOLUTION: A display device for vehicle 1 comprises a housing 2 disposed in a vehicle 100, a TFT 31 stored in the housing 2, an intermediate mirror 41, an infra-red light absorption member 5, and a thermistor 6. The intermediate mirror 41 is stored in the housing 2 to reflect display light Lt on its reflective surface 41a such that the display light Lt outputted from the TFT 31 reaches a visual observation position EP of a driver in a vehicle 100, and allows infra-red light Li included in sunlight Ls to pass through without being reflected on the reflective surface 41a. An infra-red light absorption member 5 is disposed to the side of a back surface 41b opposite to the reflective surface 41a of the intermediate mirror 41 to absorb the infra-red light Li passing through the intermediate mirror 41. The thermistor 6 is disposed on the infra-red light absorption member 5 to detect the temperature of the infra-red light absorption member 5.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, as a vehicle display device, for example, Patent Document 1 describes a head-up display device that projects an image onto a display area of a windshield so that a driver of a vehicle can visually recognize a landscape with the image superimposed thereon. This head-up display device includes an image display device that displays an image to be projected onto the display area, a light sensor that detects the intensity of sunlight irradiated on the image display device, a blocking mechanism that blocks the sunlight incident on the image display device in response to a blocking command, and a protection processing unit that issues a blocking command to the blocking mechanism to suppress a temperature rise of the image display device when the intensity of the sunlight detected by the light sensor exceeds a predetermined threshold value. Further, Patent Documents 2 to 5 describe vehicle display devices that suppress an increase in the temperature of the display device due to sunlight.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the head-up display device described in Patent Document 1 above detects the intensity of sunlight irradiated on the video display device using an optical sensor. However, for example, a vehicle display device that detects the intensity of sunlight using an infrared sensor can be considered. This vehicle display device includes, for example, a liquid crystal display element, a backlight that irradiates light on the back of the liquid crystal display element, a cold mirror that reflects the display light output from the liquid crystal display element and transmits infrared light included in sunlight, and an infrared sensor that is provided on the back side of this cold mirror and detects the infrared light that has passed through the cold mirror.

[0005] When the vehicle display device configured as described above detects infrared light that has passed through the cold mirror using an infrared sensor, it is necessary to arrange the infrared sensor at a portion where the infrared light is condensed at a distance from the back of the cold mirror, which may increase the size of the device. On the other hand, when the vehicle display device arranges the infrared sensor close to the back of the cold mirror, it is necessary to arrange a plurality of infrared sensors, which may increase the number of infrared sensors.

[0006] Therefore, the present invention has been made in view of the above, and an object thereof is to provide a vehicle display device that can appropriately detect an increase in the temperature of a liquid crystal display element due to sunlight.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, a vehicle display device according to the present invention includes a housing provided in a vehicle, a liquid crystal display element housed in the housing, and a mirror housed in the housing that reflects the display light output from the liquid crystal display element so that the display light reaches the visual position of the driver of the vehicle, and transmits infrared light included in sunlight without reflecting it on the reflecting surface, and an infrared light absorbing member provided on the back side opposite to the reflecting surface of the mirror that absorbs the infrared light that has passed through the mirror, and a temperature detection unit provided in the infrared light absorbing member that detects the temperature of the infrared light absorbing member.

Effects of the Invention

[0008] Since the vehicle display device according to the present invention detects the temperature of the infrared light absorbing member by the temperature detection unit, it is possible to suppress the increase in the size of the device and to suppress the increase in the number of temperature detection units. As a result, the vehicle display device can appropriately detect that the temperature of the liquid crystal display element rises due to sunlight.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0010] A mode (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. In addition, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0011] As shown in FIG. 1, the vehicle display device 1 of the embodiment is mounted on a vehicle 100 such as an automobile, and is a head-up display that displays a virtual image by reflecting display light Lt output toward a windshield 110 that transmits light toward the visual position EP side by the windshield 110. The vehicle display device 1 includes a housing 2, a display 3, an optical system 4, an infrared light absorbing member 5, a thermistor 6 as a temperature detection unit, a holding member 7, a transparent cover 8, and a control unit 9.

[0012] The housing 2 is housed below the dashboard of the vehicle 100. The housing 2 is formed in a box shape from a light-shielding material, houses the display 3, the optical system 4, the infrared light absorbing member 5, and the thermistor 6, and these components are fixed. The housing 2 has an opening that opens upward in the vertical direction. This opening is closed by a transparent cover 8 that transmits light.

[0013] The display 3 outputs display light Lt including an image. The display 3 is provided on the bottom 21 side of the housing 2 and has a TFT 31 and a backlight 32.

[0014] The TFT 31 is a display element having liquid crystals for displaying an image. The TFT 31 is, for example, a TFT-LCD (Thin Film Transistor-Liquid Crystal Display). The TFT 31 is a film-like member including a liquid crystal layer, a glass electrode, a polarizing plate, and the like. The TFT 31 outputs display light Lt to the optical system 4 when light is irradiated on the back surface of the TFT 31 by the backlight 32.

[0015] The backlight 32 irradiates light. The backlight 32 includes, for example, a plurality of light emitting elements made of LEDs or the like. The backlight 32 is provided to face the back surface of the TFT 31 and irradiates light on the back surface of the TFT 31. The backlight 32 is connected to the control unit 9 and irradiates light based on a command signal output from the control unit 9.

[0016] The optical system 4 reflects the display light Lt output from the display 3 toward the windshield 110. The optical system 4 includes an intermediate mirror 41 as a mirror, a final mirror 42, and a mirror drive unit 43.

[0017] The intermediate mirror 41 is, for example, a plane mirror in which the reflecting surface 41a is formed in a planar and rectangular shape. The intermediate mirror 41 is provided at a position closer to the TFT 31 than the other mirror (the final mirror 42). That is, the display light Lt output from the TFT 31 is directly incident without passing through the other mirror. The intermediate mirror 41 reflects the display light Lt on the reflecting surface 41a so that the display light Lt output from the TFT 31 reaches the visual position EP of the driver of the vehicle 100. In this example, the intermediate mirror 41 totally reflects the display light Lt output from the TFT 31 toward the final mirror 42.

[0018] The final mirror 42 is, for example, a magnifying mirror that magnifies the display light Lt, and reflects the image after reflection so that the image represented by the display light Lt after reflection is relatively larger than the image represented by the display light Lt before reflection. The final mirror 42 totally reflects the display light Lt output from the display 3 and reflected by the intermediate mirror 41 toward the windshield 110, and reflects the display light Lt toward the visual position EP side by the windshield 110. The driver of the vehicle 100 visually recognizes a virtual image by the display light Lt reflected by the windshield 110.

[0019] The mirror drive unit 43 rotates the final mirror 42. The mirror drive unit 43 is connected to the control unit 9, and rotates the final mirror 42 based on a command signal output from the control unit 9 to change the orientation of the reflecting surface that reflects the display light Lt. Thereby, the control unit 9 can display a virtual image according to the position of the eye point EP.

[0020] In this embodiment, the above-described intermediate mirror 41 is a cold mirror that reflects visible light and transmits infrared light (infrared rays), and is formed, for example, by depositing a dielectric multilayer film on a glass substrate. Here, as shown in FIG. 1, in the vehicle display device 1, sunlight Ls may enter the inside of the housing 2 through the transparent cover 8 of the housing 2. In this case, the sunlight Ls incident through the transparent cover 8 of the housing 2 is reflected by the final mirror 42, and the sunlight Ls reflected by the final mirror 42 enters the intermediate mirror 41. At this time, since the intermediate mirror 41 is a cold mirror, the infrared light Li contained in the sunlight Ls is transmitted without being reflected by the reflecting surface 41a. The infrared light Li transmitted through the intermediate mirror 41 is absorbed by the infrared light absorbing member 5 described later.

[0021] The infrared light absorbing member 5 is a member having an infrared light absorbing function. The infrared light absorbing member 5 can be formed, for example, by a graphite sheet or a thermal sheet having an infrared light absorbing function, but is not limited thereto, and may be formed by other members having an infrared light absorbing function. By forming the infrared light absorbing member 5 with a graphite sheet or a thermal sheet having excellent heat conduction, the heat of the absorbed infrared light Li can be quickly conducted to the entire infrared light absorbing member 5. Thereby, the infrared light absorbing member 5 can reduce the number of thermistors 6 provided later, and can suppress an increase in the number of parts and an increase in cost. The infrared light absorbing member 5 is formed in a rectangular shape and has the same size as the intermediate mirror 41. The infrared light absorbing member 5 is provided on the back surface 41b side opposite to the reflecting surface 41a of the intermediate mirror 41, and absorbs the infrared light Li transmitted through the intermediate mirror 41. Since the infrared light absorbing member 5 is provided on the intermediate mirror 41, compared with the case where it is provided on the final mirror 42, the infrared light Li contained in the sunlight Ls can be absorbed in a state where the infrared light Li is more condensed. Thereby, the vehicle display device 1 can appropriately detect the temperature rise of the TFT 31 by detecting the temperature of the infrared light absorbing member 5 that absorbs the more condensed infrared light Li.

[0022] The thermistor 6 is a temperature sensor that detects temperature. The thermistor 6 is provided on the infrared light absorbing member 5, and in this example, it is provided in a state of being in contact with the back surface 5b of the infrared light absorbing member 5 on the side opposite to the intermediate mirror 41 side. Here, one thermistor 6 is provided at the center of the back surface 5b of the rectangular infrared light absorbing member 5. As described above, since the infrared light absorbing member 5 is formed of a graphite sheet or the like having excellent heat conduction, the thermistor 6 can appropriately detect the temperature of the infrared light absorbing member 5 even if only one is provided at the center of the infrared light absorbing member 5. The thermistor 6 is connected to the control unit 9 and outputs the detected temperature to the control unit 9.

[0023] The holding member 7 holds the intermediate mirror 41 and the infrared light absorbing member 5. The holding member 7 holds the intermediate mirror 41 in a state where the intermediate mirror 41 faces the display 3 and the final mirror 42. Further, the holding member 7 holds the infrared light absorbing member 5 in a state where the infrared light absorbing member 5 is positioned on the back surface 41b side of the intermediate mirror 41 while holding the intermediate mirror 41. The holding member 7 holds each of them with a space therebetween between the intermediate mirror 41 and the infrared light absorbing member 5. In other words, the infrared light absorbing member 5 is provided with a space on the back surface 41b side of the intermediate mirror 41 while being held by the holding member 7. The holding member 7 holds the intermediate mirror 41 and the infrared light absorbing member 5 so that the intermediate mirror 41 and the infrared light absorbing member 5 overlap with respect to the direction in which the sunlight Ls is incident on the intermediate mirror 41.

[0024] The control unit 9 controls the display 3 and the mirror drive unit 43. The control unit 9 includes an electronic circuit mainly composed of a well-known microcomputer including a CPU, a ROM, a RAM, and an interface that constitute a storage unit. The control unit 9 performs control to suppress the temperature rise of the TFT 31 based on the detected temperature detected by the thermistor 6. For example, when the detected temperature output from the thermistor 6 is equal to or higher than a predetermined reference temperature, the control unit 9 controls the backlight 32 and relatively reduces the amount of light irradiated from the backlight 32. Then, even if the amount of light irradiated from the backlight 32 is reduced, when the detected temperature output from the thermistor 6 is equal to or higher than the reference temperature, the control unit 9 turns off the backlight 32. Further, even if the backlight 32 is turned off, when the detected temperature output from the thermistor 6 is equal to or higher than the reference temperature, the control unit 9 controls the mirror drive unit 43 to rotate the final mirror 42 so that the sunlight Ls does not enter the TFT 31. On the other hand, when the detected temperature output from the thermistor 6 is lower than the reference temperature, the control unit 9 maintains the amount of light irradiated from the backlight 32. Note that the control unit 9, the mirror drive unit 43, and the backlight 32 constitute a processing unit capable of executing a process for suppressing the temperature rise of the TFT 31 based on the temperature detected by the thermistor 6.

[0025] Next, an operation example of the vehicle display device 1 will be described. FIG. 2 is a flowchart showing an operation example of the vehicle display device 1 according to the embodiment. As shown in FIG. 2, the vehicle display device 1 detects the temperature of the infrared light absorbing member 5 by the thermistor 6 (step S1). The thermistor 6 outputs the detected temperature to the control unit 9. Next, the vehicle display device 1 determines whether or not the detected temperature output from the thermistor 6 is equal to or higher than a reference temperature by the control unit 9 (step S2). When the detected temperature output from the thermistor 6 is equal to or higher than the reference temperature (step S2: Yes), the control unit 9 executes a process of suppressing the temperature rise of the TFT 31 (step S3). The control unit 9 executes, for example, a process of relatively reducing the amount of light irradiated from the backlight 32. In step S2 described above, when the detected temperature output from the thermistor 6 is less than the reference temperature (step S2: No), the control unit 9 maintains the amount of light irradiated from the backlight 32 and ends.

[0026] As described above, the vehicle display device 1 according to the embodiment includes a housing 2 provided in the vehicle 100, a TFT 31 housed in the housing 2, an intermediate mirror 41, an infrared light absorbing member 5, and a thermistor 6. The intermediate mirror 41 is housed in the housing 2, reflects the display light Lt from the TFT 31 by the reflecting surface 41a so that the display light Lt reaches the visual position EP of the driver of the vehicle 100, and transmits the infrared light Li included in the sunlight Ls without reflecting it by the reflecting surface 41a. The infrared light absorbing member 5 is provided on the back surface 41b side opposite to the reflecting surface 41a of the intermediate mirror 41, and absorbs the infrared light Li transmitted through the intermediate mirror 41. The thermistor 6 is provided on the infrared light absorbing member 5 and detects the temperature of the infrared light absorbing member 5.

[0027] Here, as a comparative example, a vehicle display device may detect infrared light transmitted through a cold mirror by an infrared sensor. In this case, it is necessary to arrange the infrared sensor at a portion where the infrared light is condensed at a distance from the back surface of the cold mirror, which may increase the size of the device. On the other hand, when the infrared sensor is arranged closer to the back surface of the cold mirror as a comparative example, it is necessary to arrange a plurality of infrared sensors, which may increase the number of infrared sensors.

[0028] In contrast, the vehicle display device 1 according to the embodiment detects the temperature of the infrared light absorbing member 5 by the thermistor 6. Therefore, compared with the case of using an infrared sensor, the distance between the intermediate mirror 41 and the thermistor 6 can be shortened, so that an increase in the size of the device can be suppressed. Further, the vehicle display device 1 can suppress an increase in the number of thermistors 6 compared with the case of using an infrared sensor. Thereby, the vehicle display device 1 can appropriately detect that the temperature of the TFT 31 rises due to the sunlight Ls.

[0029] The vehicle display device 1 includes a holding member 7 that holds the intermediate mirror 41 and the infrared light absorbing member 5. The infrared light absorbing member 5 is provided at a distance from the back surface 41b side of the intermediate mirror 41 while being held by the holding member 7. The thermistor 6 is provided on the back surface 5b of the infrared light absorbing member 5 on the side opposite to the intermediate mirror 41 side. Thereby, the vehicle display device 1 can appropriately arrange the infrared light absorbing member 5 on the back surface 41b side of the intermediate mirror 41.

[0030] The vehicle display device 1 includes a processing unit capable of executing a process of suppressing the temperature rise of the TFT 31 based on the temperature detected by the thermistor 6. In this example, the processing unit is composed of a control unit 9, a mirror driving unit 43, and a backlight 32. For example, when the detected temperature output from the thermistor 6 is equal to or higher than a reference temperature, the vehicle display device 1 can suppress the temperature rise of the TFT 31 by relatively reducing the amount of light irradiated from the backlight 32.

[0031] Next, a modified example of the embodiment will be described. In the modified example, the same reference numerals are given to the components equivalent to those in the embodiment, and the detailed description thereof will be omitted.

[0032] FIG. 3 is a diagram showing a configuration example of a vehicle display device 1A according to a first modified example of the embodiment. The vehicle display device 1A according to the first modified example is different from the vehicle display device 1 according to the embodiment in that the infrared light absorbing member 5 is provided in close contact with the back surface 41b of the intermediate mirror 41.

[0033] The infrared light absorbing member 5 is provided, for example, by being bonded to the back surface 41b of the intermediate mirror 41 via an adhesive. One thermistor 6 is provided at the center in a state of being in contact with the back surface 5b on the side opposite to the intermediate mirror 41 side of the infrared light absorbing member 5. With this configuration, the vehicle display device 1A according to the first modified example can suppress an increase in the number of components and can be miniaturized as compared with the vehicle display device 1 according to the embodiment.

[0034] FIG. 4 is a diagram showing a configuration example of a vehicle display device 1B according to a second modified example of the embodiment. The vehicle display device 1B according to the second modified example is different from the vehicle display device 1 according to the embodiment in that the infrared light absorbing member 5 is provided on the inner surface 22 of the housing 2.

[0035] The infrared light absorbing member 5 is provided, for example, on the inner surface 22 of the housing 2 that is disposed to face the back surface 41b of the intermediate mirror 41. Specifically, the infrared light absorbing member 5 is provided on the inner surface 22 of the housing 2 so that the intermediate mirror 41 and the infrared light absorbing member 5 overlap with respect to the direction in which the sunlight Ls enters the intermediate mirror 41. One thermistor 6 is provided at the center in a state of being in contact with the front surface 5a on the intermediate mirror 41 side of the infrared light absorbing member 5. With this configuration, the vehicle display device 1B according to the second modified example can suppress an increase in the number of components and can be miniaturized as compared with the vehicle display device 1 according to the embodiment. Note that when the housing 2 of the vehicle display device 1B is formed of a material having high thermal conductivity such as metal, the infrared light absorbing member 5 may not be formed of a graphite sheet or the like having excellent heat conduction, and may be formed of a member having an infrared light absorption function without considering heat conduction.

[0036] In the above description, an example in which the infrared light absorption member 5 is provided on the intermediate mirror 41 has been described, but the present invention is not limited thereto. For example, other mirrors such as the final mirror 42 may be provided.

[0037] The intermediate mirror 41 has been described as an example of a plane mirror, but the present invention is not limited thereto. For example, an enlarged mirror, a free-form surface mirror, or the like may be used.

[0038] The final mirror 42 has been described as an example of an enlarged mirror, but the present invention is not limited thereto. For example, a free-form surface mirror, a plane mirror, or the like may be used.

[0039] The thermistor 6 has been described as an example in which one is provided at the center of the infrared light absorption member 5, but the present invention is not limited thereto. For example, a plurality of them may be provided on the infrared light absorption member 5 with a space therebetween.

[0040] An example in which a processing unit capable of executing a process for suppressing the temperature rise of the TFT 31 has been described, but the present invention is not limited thereto, and a configuration without the processing unit may be used.

Explanation of Reference Numerals

[0041] 1, 1A, 1B: Vehicle display device 2: Housing, 3: Display, 4: Optical system, 5: Infrared light absorption member 6: Thermistor (temperature detection unit), 7: Holding member 8: Transparent cover, 9: Control unit 21: Bottom, 22: Inner surface 31: TFT (liquid crystal display element), 32: Backlight 41: Intermediate mirror, 41a: Reflective surface, 41b: Back surface, 42: Final mirror, 43: Mirror drive unit 5a: Front surface, 5b: Rear surface 100: Vehicle, 110: Windshield EP: Visual position, Lt: Display light, Ls: Sunlight, Li: Infrared light

Claims

1. A housing provided in a vehicle and formed of a metal material, A liquid crystal display element housed in the housing, A mirror housed in the housing, which reflects the display light output from the liquid crystal display element so that the display light reaches the visual position of the driver of the vehicle, and transmits the infrared light contained in the sunlight without reflecting it on the reflecting surface, An infrared light absorbing member provided on the back side opposite to the reflecting surface of the mirror, which absorbs the infrared light transmitted through the mirror, A temperature detection unit provided on the infrared light absorbing member for detecting the temperature of the infrared light absorbing member, and comprising: The infrared light absorbing member is provided on the inner surface of the housing disposed opposite to the back surface of the mirror, The temperature detection unit is provided on the front surface on the mirror side of the infrared light absorbing member, and a vehicle display device characterized by this.

2. The vehicle display device according to claim 1, further comprising a processing unit capable of executing a process for suppressing a temperature rise of the liquid crystal display element based on the temperature detected by the temperature detection unit.

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