JP6299523B2 - Liquid crystal display device and head-up display device - Google Patents

Description

  The present invention relates to a liquid crystal display device and a head-up display device using the liquid crystal display device.

  As described in Patent Document 1, a conventional head-up display device includes a liquid crystal display device that generates a display image by transmitting light from a backlight, and displays a display image displayed on the liquid crystal display device. The optical system directs the displayed display light to the projection plane, thereby allowing the user to visually recognize the virtual image of the display image through the projection plane.

  In such a head-up display device, sunlight enters the inside of the head-up display device from outside, and the liquid crystal display device becomes high temperature due to heat generation of the backlight, and the liquid crystal reaches a liquefaction temperature and cannot be displayed. There was a risk of becoming.

  In order to suppress the temperature rise of such a liquid crystal display device, Patent Document 1 discloses that the intensity of sunlight is detected and the temperature of the liquid crystal display device rises when the intensity of sunlight exceeds a predetermined threshold. Therefore, the temperature increase is suppressed by reducing the light output of the backlight of the liquid crystal display device.

JP 2013-228442 A

  However, if the output of the backlight is reduced when the light intensity of the external light exceeds a predetermined threshold value, there is a problem that the visibility is lowered due to a decrease in the brightness of the virtual image.

  That is, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a liquid crystal display device and a head-up display device that have good visibility while preventing failures due to high temperatures.

  In order to solve the above problems, a liquid crystal display device according to a first aspect of the present invention includes a liquid crystal panel that displays a display image, and a back that is disposed on the back surface of the liquid crystal panel and that illuminates the liquid crystal panel for each area. A light, a temperature detector for detecting the temperature of the liquid crystal panel, and the temperature detector when the temperature of the temperature detector is equal to or higher than a predetermined temperature, the liquid crystal panel is controlled to reduce the display image, and the display image is displayed. And a control unit that controls the backlight so as to control the area to be illuminated correspondingly.

  Further, the head-up display device according to the second aspect of the present invention displays a display image and reflects the display image by a transmission / reflection surface, so that the display image is displayed to a user together with an actual scene through the transmission / reflection surface. A liquid crystal panel that displays the display image, a backlight that is disposed on the back of the liquid crystal panel and illuminates the liquid crystal panel for each area, and a temperature of the liquid crystal panel When the temperature of the temperature detection unit and the temperature detection unit is equal to or higher than a predetermined temperature, the liquid crystal panel is controlled to reduce the display image, and the illumination area is controlled corresponding to the display image And a control unit that controls the backlight, and a relay optical system that directs the display image displayed on the liquid crystal panel to the transmission / reflection surface. It is obtain things.

  Visibility can be improved while preventing failures due to high temperatures.

1 is an overview diagram showing an embodiment of the present invention. The block diagram which shows the electric constitution of embodiment same as the above. The figure which shows the example of a display of the normal display of the liquid crystal display device of embodiment same as the above. The figure which shows the example of a display of the reduced display of the liquid crystal display device of embodiment same as the above. The flowchart of the display process of embodiment same as the above.

  Hereinafter, an embodiment of a head-up display device (hereinafter referred to as a HUD device) 100 according to the present invention will be described with reference to the accompanying drawings.

  The HUD device 100 is mounted on, for example, an automobile, and as shown in FIG. 1 and the like, a housing 10, a display 20, a plane mirror (relay optical system) 30, a concave mirror (relay optical system) 40, , An actuator 50 and a control board (not shown), a display light L representing a display image M displayed by the display 20 is reflected by the plane mirror 30 and the concave mirror 40, and the vehicle on which the HUD device 100 is mounted. The display is performed by irradiating the windshield 200. The contents displayed by the HUD device 100 in this way are various vehicle information, navigation information, and the like.

The housing 10 is made of, for example, black light-shielding synthetic resin, and houses the plane mirror 30, the concave mirror 40, and the actuator 50 inside, and the display 20 and a control board (not shown) are attached to the outside.
The casing 10 has an opening 10a that allows display light L to be described later to pass through the windshield 200 at a portion facing the windshield 200, and the opening 10a is covered with a translucent cover 10b. Further, the housing 10 has a light shielding wall 10c at a location near the plane mirror 30 of the opening 10a, and external light incident from the opening 10a (translucent cover 10b) is directed to the plane mirror 30 side or the display 20 side. Prevent progress.

  The display device 20 is attached to the outside of the housing 10 and displays the display image M so as to face the display port 10d of the housing 10. The display 20 is engaged with a heat sink 20a for releasing the generated heat to the outside. The detailed configuration of the display device 20 will be described in detail.

  The plane mirror (relay optical system) 30 is formed by forming a reflective film on the surface of a base material made of, for example, a synthetic resin or a glass material by means of vapor deposition or the like, and the display light of the display image M emitted from the display device 20 L is reflected toward the concave mirror 40.

  The concave mirror (relay optical system) 40 is formed by forming a reflective film on the surface of a base material made of, for example, a synthetic resin material by means of vapor deposition or the like, and further reflects the display light L reflected by the plane mirror 30 to generate a windshield. Turn to 200. The display light L reflected by the concave mirror 40 passes through the translucent cover 10 b provided in the opening 10 a of the housing 10 and travels toward the windshield 200. The display light L that reaches and is reflected by the windshield 200 forms a virtual image of the display image M (display image visually recognized by the observer 300) V at a position in front of the windshield 200. As a result, the HUD device 100 can cause the observer 300 (mainly the driver of the vehicle) to visually recognize both the virtual image V and the outside scene that actually exists in front of the windshield 200. In addition, the concave mirror 40 has a function as a magnifying glass, and magnifies the display image M displayed on the display device 20 and reflects it to the windshield 200 side. That is, the virtual image V visually recognized by the observer 300 is an enlarged image of the display image M displayed by the display device 20.

  The actuator 50 includes a motor (not shown), a power transmission member (not shown) such as a gear that transmits the power of the motor to the concave mirror 40, and a support base (not shown) that supports the motor, the power transmission member, and the concave mirror 40. And the concave mirror 40 is rotated around the rotation axis AX. The motor generates power for rotating the concave mirror 40 around the rotation axis AX, and includes, for example, a stepping motor. The motor rotates the motor in response to an electric signal and power supply from the control unit 60 described later, and the power transmission member transmits power to the concave mirror 40 to rotate the concave mirror 40 around the rotation axis AX. When the actuator 50 is driven, the concave mirror 40 rotates about the rotation axis AX, and the position of the virtual image V visually recognized by the observer 300 can be moved. The actuator 50 may be driven based on an operation signal obtained by the observer 300 operating an operation input unit (not shown), and a signal from a viewpoint position detection unit (not shown) that detects the position of the viewpoint of the observer 300 is used. You may drive based on. Below, the specific structure of the indicator 20 is demonstrated using FIG.

  The display device 20 is a transmissive display device having a liquid crystal panel 21 and a backlight 22, and displays a display image M for informing vehicle information. The display device 20 includes a temperature detection unit 23 that detects the temperature of the liquid crystal panel 21. Furthermore, in the display device 20 according to the present invention, the backlight 22 can perform local dimming for independently dimming a plurality of areas of the liquid crystal panel 21, and only the area where the liquid crystal panel 21 displays the display image M can be selectively selected. The power consumption of the backlight 22 is reduced and the amount of heat generated by the backlight 22 is suppressed.

  The liquid crystal panel 21 is formed of a transparent material such as glass or plastic, and includes a pair of substrates (not shown) facing each other, ITO (Indium Tin Oxide), etc., and each of the surfaces facing each other of the pair of substrates. A transparent electrode (not shown) formed on the substrate, an alignment film (not shown) covering each of the transparent electrodes, a sealing material (not shown) for joining the pair of substrates, and the pair of substrates And a pair of polarizing plates (not shown) disposed so as to sandwich the substrate from the outside. The liquid crystal panel 21 is composed of a known liquid crystal panel such as a TN (Twisted Nematic) type, a VA (Vertical Alignment) type, an STN (Super-Twisted Nematic) type, and a ferroelectric type. The liquid crystal panel 21 may be either a TFT (Thin Film Transistor) type or a passive drive type. The polarizing plates are appropriately arranged according to the type (TN type, etc.) and display mode (negative / positive display) of the liquid crystal panel 21 so that the transmission axes of the polarizing plates are orthogonal or parallel to each other. (Cross Nicol or parallel Nicol arrangement).

  The backlight 22 is composed of a plurality of LEDs (Light Emitting Diodes), and is arranged in a matrix on the back side of the liquid crystal panel 21. The backlight 22 can control the lighting state of each LED independently, emits illumination light having an appropriate light intensity under the control of the control unit 60 described later, and illuminates the liquid crystal panel 21 from the back side. The display 20 performs transmissive display using the light from the backlight 22. Thereby, the display light L representing the display image M is emitted from the liquid crystal panel 21.

  The temperature detector 23 is provided for detecting the temperature of the liquid crystal panel 21. The temperature detection unit 23 is located in the vicinity of the liquid crystal panel 21 and includes, for example, a thermistor that changes its resistance value depending on the temperature. The detected temperature is converted into temperature information including an analog signal and is output to the control unit 60. The control unit 60 estimates the temperature of the liquid crystal panel 21 from the temperature information output from the temperature detection unit 23, and executes a reduced display process described later when the temperature exceeds a predetermined threshold temperature Tth. This “reduction display process” will be described later in detail.

  The control unit 60 includes an electronic circuit mounted on a control board (not shown), and is rewritable with a processing unit 61 having one or a plurality of microprocessors, microcontrollers, ASICs, FPGAs, any other ICs, and the like. A storage unit 62 having one or a plurality of memories capable of storing a program and data such as a RAM, a read-only ROM, an EEPROM for reading a program, and a flash memory which is a non-volatile memory, and a liquid crystal panel 21 , The backlight 22, the temperature detection unit 23, the actuator 50, and a vehicle ECU (not shown) so as to be able to exchange signals.

  The processing unit 61 reads image data from the storage unit 62 based on information input from the vehicle ECU, and outputs the image data to the liquid crystal panel 21, thereby displaying the display image M in a predetermined area of the display area of the liquid crystal panel 21. Is displayed.

  FIG. 3 shows an example of the display image M that the observer 300 normally recognizes. In FIG. 3, an area that the viewer 300 can visually recognize is referred to as a visual recognition area E. Of the display image M displayed on the display device 20, the one in the viewing area E is reflected by the relay optical system (the plane mirror 30 and the concave mirror 40) and is visually recognized by the observer 300 through the windshield 200. On the other hand, among the display images M displayed on the display device 20, those outside the viewing area E are not viewed by the viewer 300 because the display light L does not travel in the direction of the viewer 300.

  As shown in FIG. 3, the display image M displayed by the display device 20 includes, for example, a first display image M1 that provides route guidance, a second display image M2 that displays the speed of the host vehicle, and regulation information on the lane in which the vehicle is running. Is a third display image M3 or the like. The first display image M1 is a contact analog display that overlaps the actual scene through the windshield 200 when the observer 300 visually recognizes the front, and indicates and emphasizes a guidance route such as a branch path in the actual scene. The display image M2 and the third display image M3 are non-contact analog displays that do not indicate or emphasize a specific actual scene. Further, backlights 22 are respectively arranged in areas surrounded by dotted lines obtained by dividing the display 20 in FIG. 3 into a grid pattern. The painted areas emit illumination light, and the unfilled areas emit illumination light. Does not emit light (or emits light with low light intensity). In FIG. 3, the backlight 22 that illuminates the first display image M1 is the first illumination area BK1, the backlight 22 that illuminates the second display image M2 is the second illumination area BK2, and the backlight that illuminates the third display image M3. 22 is referred to as a third illumination area BK3. The backlight 22 emits illumination light directly below or around the display image M displayed on the liquid crystal panel 21.

  When the detected temperature T detected by the temperature detector 23 is higher than a predetermined threshold, the processing unit 61 performs a reduced display process for shifting from the normal display shown in FIG. 3 to a reduced display obtained by reducing the display image M shown in FIG. Run. Hereinafter, display processing of the HUD device 100 in the present embodiment will be described with reference to the flowchart shown in FIG.

  The processing unit 61 starts display processing after the HUD device 100 is activated. The activation of the HUD device 100 is specifically, for example, IGN-ON or ACC-ON of the host vehicle. When the display process is started, the processing unit 61 first generates a display image M in step S1. The display image M is stored in the storage unit 62 in advance, and the processing unit 61 reads image data of the display image M from the storage unit 62 based on a signal input from the host vehicle. The display image M may not be stored in the storage unit 62 inside the HUD device 100, and image data stored in an arbitrary storage unit outside the HUD device 100 may be input as a signal.

  Next, in step S <b> 2, the processing unit 61 inputs the detection temperature T that is the temperature data of the liquid crystal panel 21 from the temperature detection unit 23, and the input detection temperature T and the threshold temperature Tth stored in the storage unit 62 in advance. Are compared (step S3). When the detection temperature T is higher than the threshold temperature Tth, the process proceeds to a reduction display process (step S4) where the display image M is reduced, and when the detection temperature T is lower than the threshold temperature Tth, the display image M is normally set as a normal size. The process proceeds to display processing (step S5).

In step S4, the processing unit 61 performs reduced display processing of the display image M. The reduction display processing here may use a reduction algorithm such as the nearest neighbor method, the bilinear method, or the bicubic method. Further, reduced image data obtained by reducing the display image M may be stored in the storage unit 62 and read out as appropriate.
In step S5, the processing unit 61 performs a normal display process for displaying the display image M in a normal size.

  Next, the process part 61 produces | generates the backlight pattern suitable for the display image M in step S6. For example, the backlight 22 is turned off if a predetermined section of the liquid crystal panel 21 is black (there is no display image M to be displayed), and is turned on otherwise. It should be noted that the processing unit 61 allows the individual backlights 22 so that the luminance of the display image M does not change when the image size is changed so as to shift from reduced display to normal display or from normal display to reduced display. Adjust the output of the light source.

  Next, in step S7, the processing unit 61 displays the predetermined display image M by driving the liquid crystal panel 21 and driving the backlight 22 with the backlight pattern generated in step S6.

  The above display processing is repeated every time the display image M is generated (for each frame), and is continued only while the HUD device 100 is activated. The HUD device 100 according to the present embodiment detects the temperature of the liquid crystal panel 21 with the temperature detection unit 23, and reduces the size of the display image M displayed on the liquid crystal panel 21 when the temperature of the liquid crystal panel 21 increases. In addition, by locally dimming the backlight 22 according to the reduced display image M, the power consumption of the entire backlight 22 can be reduced, the amount of heat generated by the backlight 22 itself can be suppressed, and the liquid crystal panel 21 can be damaged. Can be prevented. In addition, when the display image M is reduced, the backlight 22 is controlled so as not to reduce the luminance of the display image M. Therefore, the liquid crystal panel 21 can be prevented from being damaged without reducing the visibility.

  In the present embodiment, the reduction direction of the display image M is the outer edge side of the liquid crystal panel 21 as shown in FIG. Thus, by reducing the display image M toward the outer edge side of the liquid crystal panel 21, the illumination area of the backlight 22 to be lit can be brought closer to the outer edge side of the liquid crystal panel 21. Incidentally, the region where the liquid crystal panel 21 is likely to rise in temperature and is easily damaged is the central region of the liquid crystal panel 21. That is, by bringing the illumination area of the backlight 22 closer to the outer edge side of the liquid crystal panel 21, it is possible to further suppress the temperature rise in the central area of the liquid crystal panel 21 and further improve the effect of suppressing the failure of the liquid crystal panel 21. Can be made.

  Further, when the display image M is reduced toward the outer edge side of the liquid crystal panel 21, the processing unit 61 drives the actuator 50 in accordance with the amount of movement of the display image M by the reduction display process, as shown in FIG. In addition, the position where the display image M is visually recognized may be automatically adjusted. When the display image M is reduced, the visible position of the display image M changes. However, by driving the relay optical system (concave mirror 40 in the present embodiment), the position of the display image M is substantially reduced and displayed. It is possible to match the previous state, and it is possible to execute a reduced display process for protecting the liquid crystal panel 21 without impairing the visibility of the display image M. In particular, when there are a plurality of display images M, the position of the first display image M1 displayed in the contact analog display at the position corresponding to the actual scene is adjusted to protect the liquid crystal panel 21 without making the viewer 300 feel uncomfortable. The reduced display process can be executed.

  In addition, this invention is not limited by the said embodiment and drawing. Of course, changes (including deletion of components) can be added to these.

  In the above description, the reduced display process is performed without changing the layout of the plurality of display images M. However, the layout of the plurality of display images M may be changed during the reduced display process. Further, each of the plurality of display images M may be moved to the vicinity of the outer edge of the liquid crystal panel 21. With such a configuration, since many illumination areas can be arranged near the outer edge of the liquid crystal panel 21, it is possible to further suppress a temperature increase in the central area of the liquid crystal panel 21, and to suppress a failure of the liquid crystal panel 21. The effect can be further improved.

  In the above embodiment, the display image M is set to the normal size or the reduced size based on the determination as to whether or not the detected temperature T exceeds the threshold temperature Tth. However, depending on the temperature of the detected temperature T, The size of the display image M may be changed continuously.

  In the above-described embodiment, the detected temperature T is detected for each frame for generating the display image M. However, the present invention is not limited to this, and the detected temperature T is detected at a predetermined time to determine the size of the display image M. You may adjust based on the judgment of the process part 61 for every time.

  Further, in the above embodiment, the reduced display processing is executed based on the temperature of the liquid crystal panel 21, but the temperature around the liquid crystal panel 21, the temperature at a predetermined location in the HUD device 100, and the outside of the HUD device 100 are installed. Based on the temperature information from the temperature detection unit (not shown), it may be determined whether or not to perform the reduced display treatment.

100 HUD device (head-up display device), 10 housing, 20 display, 30 plane mirror (relay optical system), 40 concave mirror (relay optical system), 50 actuator, AX rotation axis, L display light, M display image, V Virtual image, 200 windshield (transmission reflection surface),

Claims (5)

A liquid crystal panel for displaying a display image;
A backlight that is disposed on the back of the liquid crystal panel and illuminates the liquid crystal panel for each area;
A temperature detector for detecting the temperature of the liquid crystal panel;
When the temperature of the temperature detection unit is equal to or higher than a predetermined temperature, the liquid crystal panel is controlled to reduce the display image, and the backlight is controlled to adjust an illumination area corresponding to the display image. A control unit,
A liquid crystal display device characterized by the above. Reducing the display image toward the outer edge of the liquid crystal panel;
The liquid crystal display device according to claim 1. A head-up display device that displays a display image and reflects the display image by a transmission / reflection surface to allow a user to visually recognize a virtual image of the display image together with a real scene through the transmission / reflection surface,
A liquid crystal panel for displaying the display image;
A backlight that is disposed on the back of the liquid crystal panel and illuminates the liquid crystal panel for each area;
A temperature detector for detecting the temperature of the liquid crystal panel;
When the temperature of the temperature detection unit is equal to or higher than a predetermined temperature, the liquid crystal panel is controlled so as to reduce the display image, and the backlight is controlled so as to control an illumination area corresponding to the display image. A control unit,
And a relay optical system that directs the display image displayed on the liquid crystal panel toward the transmission / reflection surface. Reducing the display image toward the outer edge of the liquid crystal panel;
The head-up display device according to claim 3. An actuator for adjusting a position of a virtual image viewed by a user by moving or / and rotating the relay optical system;
When the display image is reduced, the actuator is controlled so that at least a part of the display image is visually recognized at substantially the same position.
The head-up display device according to claim 3.

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