JP2014074802A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that keeps optimal color balance for a display image even when sunlight is incident on the display device, and that achieves high quality image quality.SOLUTION: The display device comprises: lighting means 41 that has a first light-emitting element emitting first light of a first color and a second light-emitting element emitting second light of a second color and emits illumination light including the first light and the second light; an optical member 45 causing the illumination light to be transmitted therethrough and reflected thereon; a reflection display element 44 reflecting the illumination light transmitted through the optical member 45; detection means 46 detecting the illumination light reflected by the optical member 45 and outputting amount of light data; infrared reduction means 49 arranged between the optical member 45 and the detection means 46, and reducing infrared incident into the detection means 46; and control means 58 adjusting electric power supplied to at least one of the first light-emitting element and the second light-emitting element on the basis of the amount of light data.

Description

  The present invention relates to a display device including a reflective display element.

  Conventionally, various head-up displays for vehicles have been proposed, and for example, disclosed in Patent Document 1. Such a vehicle head-up display 1 projects display light L onto a transflective plate called a vehicle windshield or combiner to display a virtual image. The vehicle head-up display 1 includes a liquid crystal display device 4 and a reflecting mirror 5 housed in a housing 3 having a translucent window portion 2. The display light L emitted from the liquid crystal display device 4 is reflected by the reflecting mirror. 5 is reflected and projected onto the windshield or combiner (see FIG. 5).

  The liquid crystal display device 4 includes a liquid crystal display panel 6 and light emitting elements 7 and 8 that transmit and illuminate the liquid crystal display panel 6. The light emitting elements 7 and 8 emit light when supplied with a predetermined power from a drive circuit (not shown). The light emitting element 7 emits green light L1 and the light emitting element 8 emits red light L2. The liquid crystal display panel 6 is transmitted and illuminated with illumination light L3 in which green light L1 emitted from the light emitting element 7 and red light L2 emitted from the light emitting element 8 are mixed.

  However, since the light emission luminances of the light emitting elements 7 and 8 change depending on the ambient temperature, there is a problem that the illumination light L3 may not have a desired chromaticity but may have a slightly strong green color or a slightly strong red color. It was.

  In order to solve this problem, a display device that maintains the white balance by adjusting the light amount of the light emitting element has been proposed, and is disclosed in Patent Document 2, for example. Such a display device is disposed between a light source composed of a light emitting element that emits red, green, or blue color light, a light modulation element using a liquid crystal device, a projection optical system, and the light modulation element and the projection optical system. It has a detection unit and a control unit, measures the amount of light emitted from each light emitting element by the detection unit, and compares and adjusts the light amount of each light emitting element of red, green, and blue by the control unit. Therefore, even when the light emitting element deteriorates due to long-term use and the amount of light decreases, it is possible to maintain a display image with an optimal white balance. The white balance means the ratio (balance) of the amount of light emitted from the red, green and blue light emitting elements for displaying white.

  Since this display device uses a liquid crystal device as a light modulation element, light emitted therefrom is linearly polarized light. The detection unit is provided with polarization separation means having a polarization separation surface, and the linearly polarized light emitted from the liquid crystal device is transmitted through the polarization separation surface in the case of P-polarized light and reflected by the polarization separation surface in the case of S-polarization. The light is detected by guiding the S-polarized light reflected by the polarization separation surface to a light receiving element installed on the reflected light path.

In order to measure the amount of light at the detector, it is necessary to emit S-polarized light from the light modulation element, but P-polarized light is not emitted during that time. Therefore, the longer the light amount measurement time, the smaller the amount of light going to the projection optical system, and the light utilization efficiency decreases. In addition, DMD (Digital
When a reflective display element such as a micromirror device is used, light emitted from the reflective display element is non-polarized light. For this reason, in the display device disclosed in Patent Document 2, the amount of light directed to the projection optical system is approximately halved due to the influence of the polarization separation surface of the detection unit, which causes a further decrease in light utilization efficiency. Had.

  In order to solve this problem, the present applicant has proposed a display device that adjusts the power supplied to the light emitting element based on the light amount data output from the optical sensor that detects the illumination light reflected by the optical member. (Japanese Patent Application No. 2012-184713).

JP 2003-295105 A JP 2007-65012 A

However, when sunlight is incident on the display device, the optical sensor may detect not only the amount of illumination light but also the amount of sunlight, which may result in a poor color balance of the display image. In particular, when the peak wavelength of the sensitivity characteristic of the optical sensor is in the infrared region, there is a problem that the color balance of the display image is deteriorated.
The present invention provides a display device capable of maintaining an optimum color balance of a display image and obtaining a high-quality image even when sunlight is incident.

  The present invention includes an illuminating unit that emits illumination light, an optical member that transmits and reflects the illumination light, a reflective display element that reflects the illumination light transmitted through the optical member, and the optical member reflected by the optical member. And a detection unit that detects the amount of illumination light, and an infrared reduction unit that is disposed between the optical member and the detection unit to reduce infrared rays incident on the detection unit.

The present invention also includes a first light emitting element that emits first light having a first color and a second light emitting element that emits second light having a second color, and the first light. And illumination means for emitting illumination light including the second light, an optical member that transmits and reflects the illumination light, a reflective display element that reflects the illumination light transmitted through the optical member, and the optical member. Detecting means for detecting the reflected illumination light and outputting light amount data; infrared ray reducing means disposed between the optical member and the detecting means for reducing infrared rays incident on the detecting means; and the light amount data Control means for adjusting the power supplied to at least one of the first light emitting element and the second light emitting element based on
It is equipped with.

  In the present invention, the optical member comprises a prism.

  Since the infrared rays incident on the detection means can be reduced by the infrared reduction means, the chromaticity of the display light becomes a desired chromaticity.

1 is a schematic view of a head-up display showing an embodiment of the present invention. Sectional drawing which shows embodiment same as the above. The side view of the display apparatus which shows embodiment same as the above. The block diagram which shows embodiment same as the above. Sectional drawing which shows a prior art example.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  The head-up display 11 is disposed in the dashboard 12 of the vehicle (see FIG. 1). The head-up display 11 includes a display device 15, a reflector 16 and the like housed in a housing 17. The display light L projected by the head-up display 11 is reflected by the windshield 13 to the observer 14. The observer 14 can visually recognize the virtual image V superimposed on the landscape.

  The display device 15 includes a light source unit (illuminating means) 41, a mirror unit 42, a reflecting mirror 43, a DMD (reflection display element) 44, a prism (optical element) 45, an optical sensor (detection element) 46, a projection lens 47, a transmission A mold screen 48 and an infrared filter (infrared reduction means) 49 are provided, and an image is displayed by a field sequential method. The light source unit 41 of the display device 15 includes a blue light emitting diode (light emitting element) 41B, a red light emitting diode (light emitting element) 41R, and a green light emitting diode (light emitting element) 41G. In the light source unit 41 of the display device 15, the blue light emitting diode 41 </ b> B, the red light emitting diode 41 </ b> R, and the green light emitting diode 41 </ b> G are individually lit and sequentially emit blue, red, and green light.

  The mirror unit 42 includes a reflection mirror 42a and dichroic mirrors 42b and 42c. The reflection mirror 42a, the dichroic mirror 42b, and the dichroic mirror 42c are arranged in parallel to each other. The reflection mirror 42a reflects the light B emitted from the blue light emitting diode 41B. The dichroic mirror 42b reflects the light R emitted from the red light emitting diode 41R and transmits the light L1 reflected by the reflection mirror 42a. The dichroic mirror 42c reflects the light G emitted from the green light emitting diode 41G, and transmits the light L2 transmitted or reflected by the reflection mirror 42b.

  The reflection mirror 43 is a flat mirror, and reflects the light L3 from the mirror unit 12 toward the prism 45. The DMD 44 is a display element in which a large number of minute mirror surfaces are arranged in a plane, and generates display light L. The prism 45 has a triangular prism shape and is disposed between the reflection mirror 43 and the DMD 44. The prism 45 causes the inclined surface 45a to reflect a part of the light L3 to the optical sensor 46 and transmit the other part to the DMD 44. Note that an antireflection film is not formed on the inclined surface 45 a of the prism 45.

  The optical sensor 46 is a photodiode, a phototransistor, or the like, receives light reflected by the inclined surface 45 a of the prism 45, and outputs light amount data to the microcomputer 52. The peak wavelength of the sensitivity characteristic of the optical sensor 46 is in the infrared region. The projection lens 47 projects the display light L onto the transmissive screen 48. The projection lens 15 may be composed of a single lens or a plurality of lenses. The display light L is projected onto the transmissive screen 48 to generate an image. The infrared filter 49 is disposed between the prism 45 and the optical sensor 46.

  The reflector 16 includes a concave mirror 30, a holding member 31, and a stepping motor 32. The concave mirror 30 is formed by depositing a metal (for example, aluminum) on a resin (for example, polycarbonate) to form a reflective surface 30a. The reflecting surface 30a is a concave surface, and the display light L emitted from the liquid crystal display device 15 is enlarged to display the virtual image V. The concave mirror 30 is bonded to the holding member 31 with a double-sided adhesive tape. The holding member 31 is made of resin (for example, ABS), and the gear portion 34 and the shaft portion 35 are integrally formed. The shaft portion 35 of the holding member 31 is pivotally supported by the housing 17.

  A gear 37 is attached to the rotation shaft of the stepping motor 32, and the gear 37 is engaged with the gear portion 34 of the holding member 31. The concave mirror 30 is supported so as to be rotatable together with the holding member 31, and the projection direction of the display light L can be adjusted by rotating the concave mirror 30 by the stepping motor 32. The observer 14 adjusts the angle of the concave mirror 30 by operating a push button switch (not shown) so that the display light L is reflected at the position of the eyes (that is, the virtual image V can be visually recognized).

  The housing 17 accommodates the liquid crystal display device 15 and the reflector 16. The housing 17 is provided with a window portion 44 from which the display light L is emitted. The window portion 44 is made of a translucent resin (for example, acrylic) and has a curved shape. The housing 17 is provided with a light shielding wall 17c to prevent a phenomenon (washout) in which sunlight enters the liquid crystal display device 15 and the virtual image V becomes difficult to see. The light shielding wall 17 c has a flat plate shape and is formed so as to hang obliquely from the upper part of the housing 17.

  FIG. 4 is a block diagram showing an electrical configuration of the display device 15. A speed sensor 51 detects the speed of the vehicle and outputs speed data to the microcomputer 52. The optical sensor 46 outputs light amount data to the microcomputer 52. The microcomputer 52 outputs a drive signal to the DMD 44 via the drive circuit 53 to display the vehicle speed on the transmissive screen 48, and the blue light emitting diode 41 </ b> B and the red light emission via the drive circuits 54, 55 and 56. Driving signals are output to the diode 41R and the green light emitting diode 41G, and the blue light emitting diode 41B, the red light emitting diode 41R, and the green light emitting diode 41G are caused to emit light sequentially.

  The control means 58 comprises a microcomputer 52 and drive circuits 54, 55, 56, and a blue light emitting diode so that the display light L has a desired chromaticity based on the light amount data output from the optical sensor 46. The drive voltages applied to 41B, red light emitting diode 41R, and green light emitting diode 41G are adjusted.

  In the present embodiment, the light reflected by the prism 45 is detected by the optical sensor 46, and the power supplied to the light emitting diodes 41B, 41R, and 41G is adjusted based on the light amount data output by the optical sensor 46. Even if the infrared IR of sunlight is reflected by the concave mirror 30, the infrared IR is reduced by the infrared filter 49, so that the chromaticity of the display light L becomes a desired chromaticity.

  The present invention is not limited to this embodiment, and various modifications are possible. For example, the prism may be an RTIR prism or a TIR prism other than a right-angle prism. In the present embodiment, three types of light emitting diodes 41B, 41R, and 41G having different emission colors are used. For example, two types of light emitting diodes having different emission colors may be used.

41B Light Emitting Diode (Light Emitting Element)
41R Light Emitting Diode (Light Emitting Element)
41G Light Emitting Diode (Light Emitting Element)
41 Light source (illumination means)
45 Prism (optical member)
44 DMD (reflection display element)
46 Optical sensor (detection means)
49 Infrared filter (Infrared reduction means)
58 Control means

Claims (3)

  Illumination means that emits illumination light, an optical member that transmits and reflects the illumination light, a reflective display element that reflects the illumination light transmitted through the optical member, and a light quantity of the illumination light reflected by the optical member A display device comprising: a detecting means for detecting the infrared light; and an infrared ray reducing means arranged between the optical member and the detecting means for reducing infrared rays incident on the detecting means. A first light emitting element that emits first light having a first color and a second light emitting element that emits second light having a second color, the first light and the second light; Illumination means for emitting illumination light including:
An optical member that transmits and reflects the illumination light;
A reflective display element that reflects the illumination light transmitted through the optical member;
Detecting means for detecting the illumination light reflected by the optical member and outputting light amount data;
An infrared reduction means arranged between the optical member and the detection means to reduce infrared rays incident on the detection means;
Control means for adjusting the power supplied to at least one of the first light emitting element and the second light emitting element based on the light amount data;
A display device comprising:   The display device according to claim 1, wherein the optical member includes a prism.

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