Patent Application
20190346674
The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2018-091932 filed in Japan on May 11, 2018, Japanese Patent Application No. 2018-199465 filed in Japan on Oct. 23, 2018 and Japanese Patent Application No. 2019-039854 filed in Japan on Mar. 5, 2019.
The present invention relates to a vehicle display device.
Conventionally, some vehicles such as automobiles are mounted with a head up display (HUD) device. A head up display device causes a driver to visually recognize a display image displayed on a display as a virtual image by projecting the display image on a windshield or a combiner via a reflective mirror, for example. In a head up display device, when a display image displayed on a display in a housing is projected on, for example, a windshield outside the housing, an opening is provided at a top of the housing. For example, when external light such as sunlight enters from the opening and reaches the display via, for example, a reflective mirror, the display may overheat due to a light condensing action of the reflective mirror, for example.
In a conventional head up display device, a temperature sensor detects a temperature rise of a display due to external light, and when the temperature of the display exceeds a threshold temperature, dimming or turning off of the display, changing of an angle of a reflective mirror, or the like, is executed to suppress a temperature rise of the display. However, since dimming of the display, for example, is executed after the temperature of the display exceeds a threshold temperature, it is difficult to suppress a temperature rise of the display at an appropriate timing. Thus, a technique for suppressing a temperature rise at an appropriate timing by detecting infrared rays contained in external light using an infrared ray sensor is disclosed (for example, refer to Japanese Patent Application Laid-open No. 2013-228442).
In the above-mentioned related art, although infrared rays contained in external light are detected by the infrared ray sensor disposed on a back of the reflective mirror, the display is directly irradiated with the external light, and thus the display may be optically deteriorated. Therefore, it is possible to dispose a semi-transmissive polarizing plate between the reflective mirror and the display to transmit display light but not to transmit external light.
However, a rise in temperature of the semi-transmissive polarizing plate itself and around a reflective polarizing plate due to transmission of display light or irradiation of external light may heat the display disposed near the semi-transmissive polarizing plate to increase a temperature thereof and damage the display.
The present invention has been made in view of the above problems, and an object thereof is to provide a vehicle display device that prevents optical deterioration of a display due to external light and also prevents damage of a display due to external light.
In order to achieve the above mentioned object, a vehicle display device according to one aspect of the present invention includes a display that emits, as display light, a display image projected on a projection target provided outside the vehicle display device; at least one reflective mirror that is disposed on a light path of the display light from the display to the projection target and reflects the display light; a reflective optical member that is on a light path of the display light between the reflective mirror and the display and disposed at a position facing the display, transmits the display light emitted from the display toward the reflective mirror, and reflects external light directed from the reflective mirror toward the display; an optical sensor that detects external light entering from an opening communicating between the outside and an internal space; and a controller configured to execute temperature decreasing operation for reducing a temperature of the display when the optical sensor detects the external light, wherein at least one of the optical sensor is disposed at a position to which the external light directed toward the display via the reflective mirror is reflected by the reflective optical member to be directed.
According to another aspect of the present invention, in the vehicle display device, the optical sensor may be disposed on an opposite side of the opening via the reflective optical member in the internal space.
According to still another aspect of the present invention, the vehicle display device may further include a temperature sensor that detects the temperature of the display, wherein the controller may restrict execution of the temperature decreasing operation when the optical sensor detects the external light and a detected value by the temperature sensor is equal to or less than a threshold value.
According to still another aspect of the present invention, the vehicle display device may further include a temperature sensor that is at least in a vehicle and disposed outside the vehicle display device, wherein the controller may restrict execution of the temperature decreasing operation when the optical sensor detects the external light and a detected value by the temperature sensor is equal to or less than a threshold value.
According to still another aspect of the present invention, in the vehicle display device, the display may include: a transmissive liquid crystal display unit; and a backlight unit that illuminates the liquid crystal display unit from a back side, the backlight unit may be disposed facing the reflective mirror, and the reflective optical member may be disposed inclined toward the optical sensor with respect to an emission direction of light emitted from the backlight unit toward the reflective mirror.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
Hereinafter, embodiments of a vehicle display device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to these embodiments. Constituent elements in the embodiments below include those that can be easily assumed by those skilled in the art or those substantially identical. Further, various types of omissions, substitutions, or changes can be made to the constituent elements in the embodiments described below without departing from the gist of the invention.
A vehicle display device 1 is, for example as illustrated in
The housing 2 is, for example, a box made of a synthetic resin material and has an internal space 17 inside. As illustrated in
As illustrated in
The display 5 emits a display image projected on the windshield 103 as the display light L. The display 5 includes, as illustrated in
The controller 7 is, as illustrated in
The optical sensor 9 detects the external light SL entering from the opening 2a of the housing 2. The optical sensor 9 is disposed at a position to which the external light SL directed toward the display 5 via the two reflective mirrors 3, of the external light SL entering from the opening 2a of the housing 2, is reflected by the reflective optical member 27 to be directed. Specifically, the optical sensor 9 is disposed on an opposite side of the opening 2a via the display 5 in the internal space 17. The optical sensor 9 is, for example, an infrared ray sensor and detects light (infrared rays) in an infrared region of the external light SL. Specifically, the optical sensor 9 receives light (infrared rays) in the infrared region of the external light SL to convert the light into an electric signal and outputs the electric signal to the controller 7 as a detection signal.
The drive unit 15 has, for example, a structure in which a motor and a gear are combined and changes the reflection angle of the concave mirror 13. The drive unit 15 is electrically connected to the controller 7 and driven according to a drive signal from the controller 7. The drive unit 15 has, for example, a structure in which a gear attached to a rotating shaft of the motor and a plurality of teeth provided on an opposite side of the reflection surface of the concave mirror 13 mesh with one another. When the drive unit 15 receives a drive signal from the controller 7, the rotating shaft of the motor rotates, and power of the motor is transmitted to the concave mirror 13 by meshing the gear on the motor side with the teeth on a side of the concave mirror 13 to rotate the concave mirror 13 and change the reflection angle of the concave mirror 13.
The reflective optical member 27 is on a light path of the display light L between the flat mirror 11 and the display 5 and disposed at a position facing the display 5, transmits the display light L emitted from the display 5 toward the flat mirror 11, and reflects the external light SL directed from the flat mirror 11 toward the display 5. The reflective optical member 27 is made of, for example, a wire grid polarizing plate. A wire grid polarizing plate is a so-called non-absorptive polarizing plate with a metallic material evaporated on a substrate and a wire-like grid formed by fine etching at a nanometer level. Since the reflective optical member 27 is irradiated with the display light L and the external light SL, it is preferred that the reflective optical member 27 have heat resistance to such an extent that damage or deformation does not occur even when these lights are irradiated in duplicate. For example, it is preferred that the reflective optical member 27 have heat resistance equivalent to or higher than that of the liquid crystal display unit 21 of the display 5. The reflective optical member 27 of the present embodiment is disposed inclined toward the optical sensor 9 with respect to an emission direction of light emitted from the backlight unit 22 toward the flat mirror 11. The reflective optical member 27 is disposed inclined with respect to the display 5. In brief, the reflective optical member 27 is disposed inclined with respect to each of the liquid crystal display unit 21 and the backlight unit 22. The reflective optical member 27 may be supported by the housing 2 or may be supported by the display 5.
Next, display operation in the vehicle display device 1 will be described with reference to
Next, the temperature decreasing operation in the vehicle display device 1 will be described with reference to
The vehicle display device 1 described above includes the display 5 that emits a display image projected on the windshield 103 provided outside as the display light L, the reflective mirror 3 that is disposed on the light path of the display light L from the display 5 to the windshield 103 and reflects the display light L, the reflective optical member 27 that is on the light path of the display light L between the reflective mirror 3 and the display 5 and disposed at a position facing the display 5, transmits the display light L emitted from the display 5 toward the reflective mirror 3, and reflects external light directed from the reflective mirror 3 toward the display 5, the optical sensor 9 that detects the external light SL entering from the opening 2a communicating between the outside and the internal space 17, and the controller 7 that executes temperature decreasing operation for reducing the temperature of the display 5 when the optical sensor 9 detects the external light SL. The optical sensor 9 is disposed at a position to which the external light SL directed toward the display 5 via the reflective mirrors 3 is reflected by the reflective optical member 27 to be directed. With the above configuration, the external light SL directed toward the display 5 via the reflective mirror 3 is blocked by the reflective optical member 27 and does not directly reach the display 5, so that deterioration of the display 5 due to the external light SL can be prevented. In addition, since temperature decreasing operation is executed when the optical sensor 9 detects the external light SL, it is possible to suppress the temperature rise of the reflective optical member 27 due to the external light SL and to prevent damage of the display 5 by overheating.
Further, in the vehicle display device 1, the optical sensor 9 is disposed on an opposite side of the opening 2a via the reflective optical member 27 in the internal space 17. This makes it possible to suppress direct irradiation of the external light SL entering from the opening 2a to the display 5. Further, for example, the optical sensor 9 is not disposed on the light path from the display 5 to the windshield 103, and interference with the display light L by the optical sensor 9 can be prevented.
In the vehicle display device 1, the display 5 includes the liquid crystal display unit 21 and the backlight unit 22. The backlight unit 22 is disposed facing the flat mirror 11. The reflective optical member 27 is disposed inclined toward the optical sensor 9 with respect to the emission direction of the light emitted from the backlight unit 22 toward the flat mirror 11. With the above configuration, the external light SL with which the reflective optical member 27 is irradiated can be reflected toward the optical sensor 9, and detection accuracy of the external light SL by the optical sensor 9 can be improved.
Modification of First Embodiment
The inner housing 25 is formed of, for example, a synthetic resin material, housed in the internal space 17 of the housing 2, and formed so as to partition the internal space 17. The inner housing 25 is formed mainly to support the optical sensor 9 and the reflective optical member 27 but may be formed to support the reflective mirrors 3, the display 5, and the controller 7. The inner housing 25 is formed to secure a light path of the display light L from the reflective optical member 27 to the opening 2a of the housing 2. Further, the inner housing 25 is formed to secure a light path of the external light SL from the reflective optical member 27 to the optical sensor 9. The inner housing 25 has an opening 25a formed between the reflective optical member 27 and the optical sensor 9. The external light SL reflected from the reflective optical member 27 passes through the opening 25a toward the optical sensor 9.
The vehicle display device 1A includes the inner housing 25 that is housed in the housing 2 and supports at least the optical sensor 9 and the reflective optical member 27. The inner housing 25 is formed to secure a light path of display light from the reflective optical member 27 to the windshield 103 and to secure the light path of the external light SL from the reflective optical member 27 to the optical sensor 9. As a result, for example, the optical sensor 9 can receive only the external light SL, and the detection accuracy of the external light SL by the optical sensor 9 can be further improved.
In the first embodiment and the modification thereof, the reflective optical member 27 is disposed, but not limited to, inclined toward the optical sensor 9 with respect to the emission direction of the display light L. For example, the reflective optical member 27 may be disposed facing the display 5 in the emission direction of the display light L.
In the first embodiment and the modification thereof, when the optical sensor 9 detects the external light SL, the controller 7 controls, but not limited to, the display 5 and the drive unit 15 to execute one of the first temperature decreasing operation and the second temperature decreasing operation. For example, when the optical sensor 9 detects the external light SL, the controller 7 may control the display 5 and the drive unit 15 to simultaneously execute both the first temperature decreasing operation and the second temperature decreasing operation. Further, when the optical sensor 9 detects the external light SL, the controller 7 may gradually control to execute one of the first temperature decreasing operation and the second temperature decreasing operation, followed by execution of the other of the first temperature decreasing operation and the second temperature decreasing operation.
Next, a vehicle display device according to a second embodiment will be described with reference to
A vehicle display device 1B according to the second embodiment differs from the vehicle display device 1 according to the first embodiment in that a temperature sensor 29 is provided inside the display 5 as illustrated in
The temperature sensor 29 detects the temperature of the display 5 and includes, for example, a thermistor, a thermocouple, a resistance temperature detector (RTD), and an IC temperature sensor. The temperature sensor 29 is disposed in an internal space of the display 5 and is disposed near the liquid crystal display unit 21 or the backlight unit 22. The temperature sensor 29 is electrically connected to the controller 7 and outputs a detected value detected by the temperature sensor 29 to the controller 7. For example, the temperature sensor 29 may output a detected value to the controller 7 at regular intervals or may output a detected value to the controller 7 according to a request from the controller 7.
When a detected value is input from the temperature sensor 29, the controller 7 compares the detected value with a threshold value held in advance. A threshold value is a reference temperature at which the display 5 can emit the display light L with an appropriate luminance. For example, a threshold value is a lower limit temperature in an operating temperature range in which the backlight unit 22 in the display 5 can emit the display light L with an appropriate luminance. This threshold value is different from a temperature (here, a limit temperature) at which the liquid crystal display unit 21 may be damaged, and a relationship of threshold value<limit temperature is established. The controller 7 determines whether to execute the above-described temperature decreasing operation based on a detection result of the external light SL by the optical sensor 9 and a comparison result between a detected value of the temperature sensor 29 and a threshold value. When the optical sensor 9 detects the external light SL and a detected value of the temperature sensor 29 is equal to or less than a threshold value, the controller 7 of the present embodiment restricts execution of the temperature decreasing operation.
The reflective optical member 27 of the present embodiment is disposed in a direction orthogonal to the emission direction of the display light L emitted from the backlight unit 22 toward the flat mirror 11. In other words, the reflective optical member 27 is disposed facing the display 5 in the emission direction of the display light L. More specifically, the reflective optical member 27 is disposed facing each of the liquid crystal display unit 21 and the backlight unit 22 in the emission direction of the display light L.
Next, the temperature decreasing operation in the vehicle display device 1B will be described with reference to
When the optical sensor 9 detects the external light SL, the controller 7 executes the temperature decreasing operation of the display 5. However, when the temperature decreasing operation of the display 5, for example, dimming or turning off the display 5, is executed in a low temperature environment where luminance during lighting decreases, even if the temperature of the reflective optical member 27 rises due to the irradiation of the external light SL, the display 5 is unlikely to be damaged immediately. When the display 5 is dimmed or turned off even at a temperature that does not cause a damage to the display 5, sufficient luminance may not be obtained, and display quality may be degraded. Therefore, in the second embodiment, when the optical sensor 9 detects the external light SL and a detected value by the temperature sensor 29 is equal to or less than a threshold value, the controller 7 restricts dimming or turning-off of the display 5. More specifically, when the optical sensor 9 detects the external light SL and the detected value by the temperature sensor 29 is equal to or less than a threshold value, the controller 7 controls each unit so as not to execute the temperature decreasing operation.
The vehicle display device 1B described above further includes the temperature sensor 29 that detects the temperature of the display 5. When the optical sensor 9 detects the external light SL and a detected value by the temperature sensor 29 is equal to or less than a threshold value, the controller 7 restricts execution of the temperature decreasing operation. Consequently, in addition to the effects of the first embodiment, for example, when the display 5 is at a low temperature, the temperature decreasing operation is restricted even when the external light SL enters. Therefore, degradation of display quality can be suppressed.
In the second embodiment, the optical sensor 9 is disposed on, but not limited to, the opposite side of the opening 2a via the display 5 in the internal space 17. The optical sensor 9 is disposed in the internal space 17 of the housing 2 in a range where reflected light diffused (diffusion reflected light) by the external light SL striking the reflective optical member 27 reaches. For example, as illustrated in
Modification of Second Embodiment
The vehicle display device 1C includes the inner housing 25 that is housed in the housing 2 and supports at least the optical sensor 9 and the reflective optical member 27. The inner housing 25 is formed to secure a light path of display light from the reflective optical member 27 to the windshield 103 and to secure the light path of the external light SL from the reflective optical member 27 to the optical sensor 9. As a result, for example, the optical sensor 9 can receive only the external light SL, and the detection accuracy of the external light SL by the optical sensor 9 can be further improved.
In the second embodiment and the modification thereof, the temperature sensor 29 is disposed, but not limited to, inside the display 5 and may be disposed inside the vehicle display devices 1B and 1C (inside the housing 2) and outside the display 5. For example, the temperature sensor 29 may be disposed around the display 5 and disposed on a substrate that functions as the controller 7. In addition, as illustrated in
When obtaining a detected value from the temperature sensor 29 disposed inside the vehicle and outside the housing 2, the controller 7 in the modification compares a threshold value (a second threshold value corresponding to a temperature in the vehicle) different from the above-described threshold value (a first threshold value corresponding to a temperature inside the display 5) with the detected value. The second threshold value is an estimated temperature in the vehicle when the backlight unit 22 can emit the display light L with an appropriate luminance. In addition, when obtaining a detected value from the temperature sensor 29 disposed outside the vehicle and outside the housing 2, the controller 7 compares a threshold value (a third threshold value corresponding to a temperature outside the vehicle) different from the first and the second threshold values with the detected value. The third threshold value is an estimated temperature outside the vehicle when the backlight unit 22 can emit the display light L with an appropriate luminance. Thus, the controller 7 uses different threshold values to compare with a detected value according to a disposed position of the temperature sensor 29.
The vehicle display devices 1B and 1C in the modifications described above further include a temperature sensor disposed at least inside the vehicle and outside the vehicle display devices 1B and 1C. When the optical sensor 9 detects the external light SL and a detected value by the temperature sensor 29 is equal to or less than a threshold value (the second or the third threshold value), the controller 7 restricts execution of the temperature decreasing operation. Consequently, in addition to the effects of the first embodiment, for example, when the vehicle 100 is placed in a low temperature environment, the temperature decreasing operation is restricted even when the external light SL enters. Therefore, degradation of display quality can be suppressed. Further, since the temperature sensor 29 is not disposed inside the vehicle display devices 1B and 1C, it is possible to ensure flexibility in layout of the temperature sensor 29 and contribute to downsizing of the housing 2.
In the second embodiment and the modification thereof, when the optical sensor 9 detects the external light SL and a detected value by the temperature sensor 29 exceeds a threshold value (a first threshold value, a second threshold value, or a third threshold value), the controller 7 controls, but not limited to, the display 5 and the drive unit 15 to execute one of the first temperature decreasing operation and the second temperature decreasing operation. For example, when the optical sensor 9 detects the external light SL and a detected value by the temperature sensor 29 exceeds a threshold value, the controller 7 may control the display 5 and the drive unit 15 to simultaneously execute both the first temperature decreasing operation and the second temperature decreasing operation. Further, when the optical sensor 9 detects the external light SL and a detected value by the temperature sensor 29 exceeds a threshold value, the controller 7 may gradually control to execute one of the first temperature decreasing operation and the second temperature decreasing operation, followed by execution of both the first temperature decreasing operation and the second temperature decreasing operation.
Further, a plurality of temperature sensors 29 may be disposed at different places with respect to the vehicle 100. For example, the temperature sensor 29 may be disposed inside the display 5 and may be disposed inside and outside the vehicle 100. In this case, since different detected values are output from the temperature sensors 29, respectively, the controller 7 may restrict execution of the temperature decreasing operation by selecting one detected value from among the detected values based on certain conditions and comparing the selected value with a threshold value corresponding to the temperature sensor 29 that outputs the one detected value. This temperature decreasing operation includes both the first temperature decreasing operation and the second temperature decreasing operation.
Moreover, in the second embodiment and the modification thereof, the reflective optical member 27 is disposed, but not limited to, facing the display 5 in the emission direction of the display light L. For example, the reflective optical member 27 may be disposed inclined toward the optical sensor 9 with respect to the emission direction of the display light L.
In the modifications of the first and second embodiments, the reflective optical member 27 is supported by, but not limited to, the inner housing 25 and may be supported by the display 5 as illustrated in
In the first and second embodiments and the modifications thereof, the vehicle display devices 1, 1A, 1B, and 1C have, but not limited to, two reflective mirrors 3 and may have one reflective mirror 3 or may have three or more reflective mirrors 3. The flat mirror 11 may be a concave mirror, or may be, for example, a convex mirror, an aspheric mirror, a spherical mirror, or a free-form mirror. The concave mirror 13 may be, for example, a convex mirror, an aspheric mirror, a spherical mirror, or a free-form mirror.
In the first and the second embodiments and the modifications thereof, the concave mirror 13 has a function as, but not limited to, a magnifying mirror and may have a function as a correction mirror.
In the first and the second embodiments and the modifications thereof, the concave mirror 13 is supported by, but not limited to, the drive unit 15 rotatably and may be immovably supported by the housing 2 or the inner housing 25 immovably. The flat mirror 11 is immovably supported by the housing 2 or the inner housing 25 but may be, as with the concave mirror 13, rotatably supported by a drive unit.
Further, positions of the display 5 and the reflective mirror 3 in the first and the second embodiments and the modifications thereof are not limited to the positions as illustrated.
In the first and the second embodiments and the modifications thereof, the opening 2a may be closed by a transparent cover that transmits the display light L. A transparent cover prevents entry of, for example, dust into the housing 2 from outside by closing the opening 2a.
In the first and the second embodiments and the modifications thereof, the display 5 is a liquid crystal type but may be other types such as a laser type, a digital light processing (DLP) type, and a projector type.
In the first and the second embodiments and the modifications thereof, in the internal space 17 of the housing 2, one optical sensor 9 is disposed, but not limited to one optical sensor 9, a plurality of optical sensors 9 may be disposed. In this case, as long as the position is a position where the external light SL reflected from the display 5 enters, the optical sensors 9 may be disposed at one position or may be disposed at positions different from one another.
In the first and second embodiments and the modifications thereof, the optical sensor 9 is an infrared ray sensor but may be, for example, an illuminance sensor as long as the external light SL can be detected. When the optical sensor 9 is an illuminance sensor, the optical sensor 9 receives light (visible light) in a visible region of the external light SL, converts the light into an electric signal, and outputs the electric signal to the controller 7. In addition, one of an infrared ray sensor and an illuminance sensor may be disposed in the optical sensor 9, or both the infrared ray sensor and the illuminance sensor may be disposed.
Moreover, in the first and the second embodiments and the modifications thereof, the reflective optical member 27 is, but not limited to, a wire grid polarizing plate. The reflective optical member 27 may be a semi-transmissive member capable of transmitting the display light L directed from the display 5 toward the flat mirror 11 and reflecting the external light SL directed from the flat mirror 11 toward the display 5 and may be, for example, a half mirror, a cold mirror, or a hot mirror. The reflective optical member 27 may be disposed apart from a display surface of the display 5 regardless of presence/absence of the inner housing 25 or may be disposed contacting the display surface.
In the first and the second embodiments and the modifications thereof, the temperature sensor 29 outputs a detected value, but not limited to, directly to the controller 7. For example, the temperature sensor 29 may output a detected value to the controller 7 via the meter 104 or the ECU 105.
In the first and the second embodiments and the modifications thereof, the vehicle display devices 1, 1A, 1B, and 1C project a display image on, but not limited to, the windshield 103 of the vehicle 100 and may project a display image on a combiner, for example.
In the first and the second embodiments and the modifications thereof, the vehicle display devices 1, 1A, 1B, and 1C are applied to, but not limited to, the vehicle 100 such as an automobile, and may be applied to, for example, ships or aircrafts other than the vehicle 100.
A vehicle display device according to the present embodiments and modifications can advantageously prevent optical deterioration of a display due to external light and prevent damage of a display due to external light.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-091932 | May 2018 | JP | national |
| 2018-199465 | Oct 2018 | JP | national |
| 2019-039854 | Mar 2019 | JP | national |
