JP2018091994A - Display device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device for a vehicle which is excellent in display quality.SOLUTION: The display device for a vehicle comprises: light sources 11a to 11c comprising light emitting didoes which output respective colors for emitting light of three original colors; a display unit 14 for generating an image to be projected by using light outputs from the light sources 11a to 11c; a temperature sensor 112 for detecting and outputting temperature of the light sources 11a to 11c as temperature information; a light source driving circuit 110c for driving the light sources 11a to 11c; a display unit control circuit 110d for driving the display unit 14; and a control part 110b for controlling the light source driving circuit 110c for dimming light on the basis of the temperature information. The control part 110b adjusts a hue of the image under control by the display unit control circuit 110d when the temperature information is equal to or more than a predetermined value.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a vehicle display device, and is suitable, for example, as a vehicle display device that generates display light by modulating and synthesizing light of three primary colors with image information.

  In the conventional illumination structure of a display device for a vehicle, a discharge lamp such as a metal halide lamp or an ultrahigh pressure mercury lamp is employed as a light source (RGB light source) for generating light of three primary colors. White light emitted from the discharge lamp is separated into three primary colors of red (R), green (G), and blue (B) by a dichroic mirror, and these three primary colors are modulated by image information and synthesized by a synthesis prism (dichroic prism). Then, for example, there is one that performs light source output for displaying an image on a screen by outputting, and is disclosed in Patent Document 1, for example.

JP 2009-86269 A

  When a light emitting diode is applied as the light source of these vehicle display devices, the red light source among the RGB light sources has characteristics that the color changes or the light output decreases as the temperature rises. For example, when expressing white, there is a problem in that it cannot be adjusted to a good white balance.

  Accordingly, an object of the present invention is to provide a vehicle display device with excellent display quality, paying attention to the above-described problems.

In order to achieve the above object, a vehicle display device according to the present invention includes:
In order to emit light of three primary colors, a light source composed of a light emitting diode that outputs each color,
A display that generates an image for projection using the light output from the light source;
A temperature sensor that detects the temperature of the light source and outputs it as temperature information;
A light source driving circuit for driving the light source;
A display control circuit for driving the display;
A controller that controls the light source drive circuit based on the temperature information and performs light control,
The control unit adjusts the color of the image by the control by the display control circuit when the temperature information is equal to or greater than a predetermined value.

In addition, when the temperature information is equal to or greater than a predetermined value, the control unit is configured to reduce or reduce the drive current of the light source that emits red,
The color of the image is adjusted by the control by the display control circuit.

Further, the display control circuit drives the light source so as to emit a desired color by changing a gradation level relating to the shade of display color of the image,
The control unit is configured to adjust the color of the image by changing the gradation level when the temperature information is equal to or greater than a predetermined value.

  According to the present invention, it is an object to provide a display device for a vehicle having excellent display quality.

1 is an overview diagram showing an embodiment of the present invention. Sectional drawing of the display apparatus of embodiment same as the above. Sectional drawing of the 1st unit of embodiment same as the above. Sectional drawing of the light source part of embodiment same as the above. The block diagram regarding the drive control of the light source and display of embodiment same as the above. The flowchart which shows the predetermined procedure of embodiment same as the above. The figure which shows the relationship between the atmospheric temperature value and drive current value of embodiment same as the above. The figure which shows the relationship between the atmospheric temperature value and gradation level of embodiment same as the above. The figure which shows the relationship between the atmospheric temperature value and gradation level of embodiment same as the above.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a vehicle display device according to the present invention is mounted on a head-up display will be described with reference to the accompanying drawings.

  The head-up display reflects the display light L projected by the display device (vehicle display device) 2 provided on the dashboard 1 of the vehicle to the vehicle driver 4 side by the front windshield (front glass) 3, and the virtual image V Is displayed. The vehicle driver 4 can visually recognize the virtual image V superimposed on the landscape. The display device 2 includes a first unit A1 and a second unit B1.

  The first unit A1 includes a projector 10, a plane mirror 21, a transmission screen 26, a heat sink 31, a housing 41, and the like. The second unit B1 includes reflectors 50 and 60, a housing 71, and the like.

  The projector 10 displays an image on the transmissive screen 26 by a field sequential method. The projector 10 includes a light source unit 11, a mirror unit 12, a prism 13, a display 14, and a projection lens member 15, and is fixed to a heat sink 31.

  The light source unit 11 of the projector 10 includes a blue light emitting diode 11a, a red light emitting diode 11b, a green light emitting diode 11c, lens members 11d, 11e, 11f, a reflecting mirror 11g, dichroic mirrors 11h, 11i, and a circuit board 11k. The lens members 11d, 11e, 11f, the reflection mirror 11g, and the dichroic mirrors 11h, 11i are held by the holding portion 11v of the frame member 11m.

  A light source having a blue light emitting diode 11a, a red light emitting diode 11b, and a green light emitting diode 11c is a top-view LED, and emits blue light B, red light R, and green light G, respectively. The blue light emitting diode 11a, the red light emitting diode 11b, and the green light emitting diode 11c are mounted on the circuit board 11k. The circuit board 11k on which the blue light emitting diode 11a, the red light emitting diode 11b, and the green light emitting diode 11c are mounted is fixed to the heat sink 31 with bolts (not shown). The circuit board 11k is in contact with the heat sink 31, and the heat generated by the blue light emitting diode 11a, the red light emitting diode 11b, and the green light emitting diode 11c is dissipated by the heat sink 31 through the circuit board 11k.

  The lens members 11d, 11e, and 11f collect the blue light B, red light R, and green light G emitted from the blue light emitting diode 11a, the red light emitting diode 11b, and the green light emitting diode 11c, respectively. The reflection mirror 11g reflects the blue light B emitted from the blue light emitting diode 11a and collected by the lens member 11d. The dichroic mirror 11h reflects the red light R emitted from the red light emitting diode 11b and collected by the lens member 11e, and transmits the blue light B reflected by the reflection mirror 11g. The dichroic mirror 11i reflects the green light G emitted from the green light emitting diode 11c and collected by the lens member 11f, and transmits the blue light B and red light R transmitted or reflected by the reflecting mirror 11g and the dichroic mirror 11h. Let

  The display unit 19 houses the mirror unit 12, the prism 13, the display 14, and the projection lens member 15 in a case body 18. The display unit 19 is not in direct contact with the light source unit 11. The prism 13 transmits the light from the mirror unit 12 and irradiates the display 14 with the light. The display light L generated by the display unit 14 is reflected toward the projection lens member 15 by the inclined surface 13 a of the prism 13. The projection lens member 15 enlarges the display light L and projects it onto the plane mirror 21. The projection lens member 15 may be composed of a single lens member or a plurality of lens members.

  The plane mirror 21 is held by the holding member 23 and reflects the display light L from the projector 10 to the transmissive screen 26. The transmissive screen 26 is held by the holding member 24, and the display light L from the projector 10 is imaged on the transmissive screen 26. The heat sink 31 is made of metal such as aluminum and has a plurality of heat radiation fins 31a. The plane mirror 21 and the transmission screen 26 are fixed to the heat sink 31 via holding members 23 and 24. The housing 41 is a combination of opaque resin (for example, polypropylene) or metal, and houses the projector 10, the flat mirror 21, the transmission screen 26, and the like. The housing 41 is formed with a window 41a from which the display light L is emitted.

  The reflector 50 includes a plane mirror 51 and a support member 52. The plane mirror 51 reflects the display light L from the first unit A1 to the concave mirror 61. The support member 52 is fixed to the housing 71 and holds the plane mirror 35. The reflector 60 includes a concave mirror 61, a mirror holder 62, a stepping motor 63, and a support member 64. The concave mirror 61 has a reflective surface 61a formed by vapor-depositing a metal (for example, aluminum) on a resin (for example, polycarbonate). The reflecting surface 61a is a concave surface, and the display light L reflected by the plane mirror 51 is enlarged to display the virtual image V. The concave mirror 61 is bonded to the mirror holder 62 with a double-sided adhesive tape. The mirror holder 62 is made of resin (for example, ABS), and the gear portion 65 and the shaft portion 66 are integrally formed.

  A gear 67 is attached to the rotation shaft of the stepping motor 63, and this gear 67 is engaged with the gear portion 65 of the mirror holder 62. The concave mirror 61 is supported in a rotatable state together with the mirror holder 62, and the projection direction of the display light L can be adjusted by rotating the concave mirror 61 by the stepping motor 63. The vehicle driver 4 operates a push button switch (not shown) to adjust the angle of the concave mirror 61 so that the display light L is reflected at the eye position (that is, the virtual image V can be visually recognized).

  The housing 71 is made of an opaque resin (for example, polypropylene) and accommodates the reflectors 50 and 60. The housing 71 is provided with a light shielding wall 71a to prevent a phenomenon (washout) in which external light such as sunlight enters the transmission screen 26 and the virtual image V becomes difficult to see. The light shielding wall 71 a has a flat plate shape and is formed so as to hang obliquely from the top of the housing 71. An opening 71b through which the display light L is emitted is formed on the upper surface of the housing 71, and a translucent cover 72 is attached to the opening 71b. The translucent cover 72 is made of a transparent resin such as polycarbonate and has a curved shape.

  Next, based on FIG. 5, the structure regarding the drive control of the light sources 11a-11c and the indicator 14 is demonstrated.

  The first unit A1 includes a circuit board (not shown) and has a microcomputer 110 mounted thereon. The microcomputer 110 is connected to an illuminance sensor 111 and a temperature sensor 112 in addition to driving and controlling the light sources 11 a to 11 c and the display 14. The microcomputer 110 is connected to another electronic control unit via a communication line (not shown), and the display output content of the display device 2 can be determined by communication via the communication line.

  The microcomputer 110 includes a memory 110a that stores information such as predetermined program data, various table data, and parameters, and a control unit 110b that performs arithmetic processing based on the information and generates and outputs a control signal based on the program. Yes. Further, the microcomputer 110 is provided with a light source driving circuit 110c that operates based on a control signal from the control unit 110b and a display control circuit 110d.

  The light source drive circuit 110c is a circuit that outputs a drive signal to each of the light sources 11a to 11c based on a control signal from the control unit 110b, and a switch circuit such as a transistor is applied. In this case, the light source drive circuit 110c can generate a drive signal with a drive current value or a duty ratio based on the control signal from the control unit 110b, and can adjust the light output of the light sources 11a to 11c. The light source driving circuit 110c can adjust the driving current value to the light sources 11a to 11c based on the detection signal from the illuminance sensor 111, and a desired light output is made to each of the light sources 11a to 11c. Each of them has a circuit for adjusting. The light source driving circuit 110c adjusts the output by a field sequential method in which the light sources 11a to 11c are sequentially turned on.

  The display control circuit 110d is provided with a drive circuit for driving the display 14, and can be driven and controlled so that a desired image is output from the display 14 based on a control signal from the control unit 110b. The display control circuit 110d includes an arithmetic processing circuit like the control unit 110b, and has a memory 110e for storing various table data and the like.

  The illuminance sensor 111 detects the intensity of light output emitted from the light sources 11a to 11c, and a sensor using a photodiode can be applied. The illuminance sensor 111 is disposed on the optical path of the display light L emitted from the light sources 11 a to 11 c so that light that is not used for projection onto the front windshield 3 can be input. A detection signal (illuminance information) corresponding to the light output value detected by the illuminance sensor 111 is output to the light source driving circuit 110c. In this case, the illuminance sensor 111 turns on the RGB light sources 11a to 11c one by one by driving control of the control unit 110b and the light source driving circuit 110c, and reads the detection signal of the illuminance sensor 111 in accordance with the lighting timing. The output values of the RGB light sources 11a to 11c are detected. Note that these output values are always read during display output. However, depending on the arrangement and configuration of the illuminance sensor 111, the output values may be detected at a timing not related to display.

  The temperature sensor 112 is for detecting the ambient temperature (environmental temperature) of the light sources 11a to 11c or the temperature of the light sources 11a to 11c itself, and in this case, is mounted on the circuit board 11k. The temperature sensor 112 outputs a detection signal (temperature information) corresponding to the temperature to the control unit 110b. In this case, the ambient temperature value of the red light emitting diode 11b that emits red light is detected as a representative value. However, it can be provided so as to correspond to the light sources 11a to 11c of the three primary colors, respectively.

  As described above, a light emitting diode can be applied to the light sources 11a to 11c.

  The display 14 is for generating a desired display image based on a drive signal from the display control circuit 110d, and a reflective display element such as DMD (Digital Micromirror Device) can be applied.

  The display device 14 has a large number of minute mirror surfaces arranged in a plane. The display device 14 includes a plurality of movable mirror elements, and the electrodes provided below the mirror elements are driven in a very short time so that each mirror can be driven. The mirror surface of the element is inclined with the hinge as a fulcrum. For example, when the mirror element is on, it is inclined +12 degrees with the hinge as a fulcrum, and the display light L emitted from the display unit 19 is reflected and delivered to the screen 26 via the prism 13 or the like. When it is off, the hinge is tilted by -12 degrees with respect to the fulcrum, and the display light L is not reflected in the direction of the prism 13. Thus, by driving each mirror element individually based on the display image data representing the display image, the display light L is selectively projected onto the screen 26, so that a display image having a desired luminance and a desired color can be obtained. It is generated on the screen 26 described later.

  Next, a control process related to output adjustment will be described with reference to FIG.

  The controller 110b inputs a detection signal from the temperature sensor 112 (step S1). The input of the detection signal includes analog / digital conversion, and the control unit 110b measures the ambient temperature values (temperature values) of the light sources 11a to 11c. In this case, the following processing is performed based on the ambient temperature value of the red light emitting diode 11b.

  The controller 110b determines whether or not the temperature value measured in step S1 is equal to or greater than a predetermined value (threshold value) (step S2). As this predetermined value, an allowable temperature upper limit value of the red light emitting diode 11b is set. Note that the red light emitting diode 11b has a lower temperature upper limit than the other light sources 11A and 11C, and has a luminance even when the same drive current value is applied when the temperature exceeds the predetermined value. There is a possibility that problems such as reduction or inability to produce a desired color may occur.

  When the temperature value measured by the determination process in step S2 is less than the predetermined value, the control unit 110b stores the drive current value based on the ambient temperature of the light sources 11a to 11c in the memory 110a as a normal process. Set based on the stored first table data (step S3). This is because the output luminance of the light sources 11a to 11c changes depending on the temperature environment, and correction is made so that a desired output is made in accordance with this change. For example, as shown in FIG. 7, the drive current value of each of the light sources 11a to 11c can be set according to the measured temperature value in a range less than a predetermined value Ta, and the drive current value approximately proportional to the ambient temperature is set. .

  In addition, when the temperature value measured by the determination process in step S2 is equal to or greater than the predetermined value Ta, the control unit 110b assumes that the temperature has increased more than usual, and the drive current values of the light sources 11a to 11c. Is set based on the second table data stored in the memory 110a (step S4). At this time, each of the light sources 11a and 11c is set with a driving current value based on the measured temperature value, and the light source 11b reduces the constant driving current value or the driving current value according to the increase in the ambient temperature. Can be set to a value. The former case where the light source 11b is set to a constant drive current value will be described as case C1, and the latter case will be described as case C2.

  As a result of the processing in step S4, the output balance of the light sources 11a to 11c is lost, so that a desired color cannot be expressed. In order to interpolate this, the control unit 110b performs color adjustment by the display unit 14 through the display unit control circuit 110d by the following steps S5 to S7.

  In step S5, the control unit 110b determines whether or not the gradation regarding the red output of the display 14 driven by the display control circuit 110d is smaller than a predetermined value in any pixel. This predetermined value may be a maximum value. Note that the gradation of each color is associated with a lighting time per unit time or a lighting frequency in field sequential, and is set in advance. This setting information is stored in the memory 110e as table data or parameters.

  As a result of the determination process in step S5, when the gradation related to red output is smaller than a predetermined value, the display control circuit 110d displays red when the ambient temperature is equal to or higher than the predetermined value Ta as shown in FIG. The display 14 is driven so that the gradation is increased and red is felt strongly (step S6). Thereby, even if the luminance output of red decreases, a desired color can be expressed.

  Further, if the condition is not satisfied by the determination process in step S5, that is, if the red gradation cannot be increased, the green and blue gradations are reduced as shown in FIG. The light sources 11a to 11c are driven so as to keep the color balance output to (step S7).

  In Steps S5 to S7, when the driving current of the red light emitting diode 11b is made constant (case C1), the allowable upper limit temperature due to the temperature compensation range of the red light emitting diode 11b based on the detection signal from the temperature sensor 112. When the value Tb (a value higher than the predetermined value Ta) is reached, the drive current of the red light emitting diode 11b is forcibly reduced, and the drive current and gradation setting of the case C2 shown in FIGS. By doing so, it is possible to suppress the temperature rise caused by the heat generation of the light emitting diode 11b itself.

  The control unit 110b controls the light sources 11a to 11c and the display 14 with the values set in step S3 or steps S4 to S7, and the light source driving circuit 110c is further based on the detection signal from the illuminance sensor 111. Feedback control and correction of the drive currents of the light sources 11a to 11c (step S8) makes it possible to output a desired color with higher accuracy.

  By repeating the processes of steps S1 to S8 described above, the control unit 110b is mounted on the vehicle, and can maintain an output with a desired color even under a severe temperature environment in the dashboard 1. In particular, by maintaining the white balance of the display image, the display device 2 performs display output without a sense of incongruity.

  Since the display device 2 emits light of the three primary colors, the light sources 11a to 11c including light-emitting diodes that output the respective colors, and a display that generates an image for projection using the light outputs from the light sources 11a to 11c. A temperature sensor 112 that detects the temperature of the light sources 11a to 11c and outputs it as temperature information, a light source drive circuit 110c that drives the light sources 11a to 11c, a display control circuit 110d that drives the display 14, A control unit 110b that controls the light source driving circuit 110c based on the temperature information and adjusts the light. When the temperature information is equal to or higher than a predetermined value, the control unit 110b is controlled by the display control circuit 110d. Adjust the color of the image.

  Therefore, even in a harsh temperature environment, it is possible to output with a desired color, display without discomfort, and a display device with excellent display quality.

  In addition, when the temperature information is equal to or higher than a predetermined value, the control unit 110b makes the driving current of the light source 11b emitting red light constant or decreases, and controls the color of the image by the control by the display control circuit 110d. adjust. Therefore, an image can be output with a desired color and a display device with excellent display quality can be obtained. Moreover, since the heat generation of the light source 11b can be suppressed, it is possible to prevent the temperature from rising further.

  The display control circuit 110d drives the light sources 11a to 11c so as to emit a desired color by changing the gradation level relating to the shade of the display color of the image, and the control unit 110b has the temperature information equal to or higher than a predetermined value. In some cases, the tone level is changed to adjust the color of the image. Therefore, even in a severe temperature environment, the display device has excellent display quality.

  Although the present invention has been described by way of example in the configuration of the above-described embodiment, the present invention is not limited to this, and various other configurations can be used without departing from the spirit of the present invention. Of course, it is possible to improve the display and change the display. For example, in the above-described embodiment, the display unit 14 made of DMD has been described as an example. However, a liquid crystal display is applied as the display unit, or a laser beam is raster-scanned by a MEMS scanner and synchronized with a video signal. Then, it can also be applied as a display structure of a scanning laser display that draws by modulating laser light, and the same effects as those of the above-described embodiment can be obtained.

  The present invention relates to a display device for a vehicle, for example, an in-vehicle head-up that is mounted on a moving body including an automobile, a motorcycle, an agricultural machine, or a construction machine, and projects and displays road information such as vehicle information and turn-by-turn display. It is suitable as a display.

2 Display device (Vehicle display device)
11a to 11c Light source 110b Control unit 110c Light source drive circuit 110d Display control circuit 111 Illuminance sensor 112 Temperature sensor 14 Display

Claims (3)

In order to emit light of three primary colors, a light source composed of a light emitting diode that outputs each color,
A display that generates an image for projection using the light output from the light source;
A temperature sensor that detects the temperature of the light source and outputs it as temperature information;
A light source driving circuit for driving the light source;
A display control circuit for driving the display;
A controller that controls the light source drive circuit based on the temperature information and performs light control,
The said control part adjusts the color of the said image by control by the said display control circuit, when the said temperature information is more than predetermined value, The display apparatus for vehicles characterized by the above-mentioned. When the temperature information is equal to or higher than a predetermined value, the control unit is configured to reduce or drive the driving current of the light source that emits red light,
The vehicle display device according to claim 1, wherein the color of the image is adjusted by the control by the display control circuit. The display control circuit drives the light source so as to emit a desired color by changing a gradation level related to the shade of display color of the image,
3. The vehicle according to claim 1, wherein the control unit adjusts the color of the image by changing the gradation level when the temperature information is equal to or greater than a predetermined value. 4. Display device.

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