WO2008023542A1

WO2008023542A1 - Liquid crystal display device

Info

Publication number: WO2008023542A1
Application number: PCT/JP2007/064946
Authority: WO
Inventors: Takashi Yamazoe; Kazuyoshi Yamada; Yoshihiko Abe
Original assignee: Nippon Seiki Co., Ltd.
Priority date: 2006-08-23
Filing date: 2007-07-31
Publication date: 2008-02-28

Abstract

It is possible to provide a liquid crystal display device in which a liquid crystal display panel is uniformly transmittance-illuminated and a display light has a desired chromaticity. Illumination means (19) includes a first light emitting element (20) for emitting a first light (L1) having a first color and a second light emitting element (21) for emitting a second light (L2) having a second color. An illumination light (L3) containing the first light (L1) and the second light (L2) is applied to a liquid crystal display panel (18). A light conducting member (27) reflects a part (L4) of the illumination light (L3) so as to be introduced to a color sensor (28). The color sensor (28) detects chromaticity of a part (L4) of the illumination light (L3) reflected by the light conducting member (27) and outputs the chromaticity data. Control means adjusts power supplied to at least one of the first light emitting element (20) and the second light emitting element (21) according to the chromaticity data. The present invention may be applied to a head up display for projecting a display light emitted from the liquid crystal display panel to a vehicle front glass (or a translucent plate called combiner) so as to display a virtual image.

Description

Specification

Liquid crystal display

Technical field

The present invention relates to a liquid crystal display panel and a liquid crystal display device having a light emitting element such as a light emitting diode that illuminates the liquid crystal display panel.

Background art

Conventionally, various vehicle head-up displays using a liquid crystal display device 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 a complier 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. It is reflected by the mirror 5 and projected onto the windshield or complier (see Fig. 8).

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

Patent Document 1: Japanese Patent Laid-Open No. 2003-295105

Disclosure of the invention

Problems to be solved by the invention

[0004] However, since the light emission luminances of the light emitting diodes 7 and 8 change depending on the ambient temperature, the illumination light L3 may have a slightly strong green color or a slightly strong red color at a desired chromaticity. Had a problem. In order to solve this problem, a color sensor that detects the chromaticity of the illumination light L3 is provided, and the voltage applied to the light emitting diodes 7 and 8 is adjusted in accordance with the chromaticity data output by the color sensor, so that the illumination light L3 chromaticity is always the desired chromaticity The power to make S is considered. However, when the color sensor is disposed between the light emitting diodes 7 and 8 and the liquid crystal display panel 6, the illumination light L3 may be blocked by the color sensor, and the liquid crystal display panel 6 may not be transmitted and illuminated uniformly.

The present invention provides a liquid crystal display device in which a liquid crystal display panel is uniformly transmitted and illuminated, and display light L has a desired chromaticity.

Means for solving the problem

[0005] The present invention provides a liquid crystal display panel, illumination means for emitting illumination light for illuminating the liquid crystal display panel, detection means for detecting chromaticity of the illumination light, and detecting part of the illumination light. And a light guide member guided to the exit means.

[0006] The present invention also includes a liquid crystal display panel, 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. Illumination means for illuminating the liquid crystal display panel with illumination light including the first light and the second light;

Based on the chromaticity data, reflecting means for reflecting a part of the illumination light, detecting means for detecting chromaticity of a part of the illumination light reflected by the reflecting means, and outputting chromaticity data And control means for adjusting electric power supplied to at least one of the first light emitting element and the second light emitting element.

[0007] Further, the present invention is characterized in that the reflecting means comprises a light guide member having a reflecting surface for reflecting the illumination light.

[0008] Further, the present invention is characterized in that the light guide member has a condensing part for condensing the illumination light reflected through the reflecting surface at a portion facing the detection means.

[0009] In the present invention, the illuminating means transmits the first light L1 emitted from the first light emitting element and reflects the second light emitted from the second light emitting element. It has a reflection member.

[0010] The present invention is characterized in that a circuit board on which the second light emitting element and the detection means are mounted is provided.

The invention's effect

[0011] By adopting a structure in which a part of the illumination light is reflected by the reflection means to the detection means, the liquid crystal display panel in which the detection means does not block the illumination light is uniformly illuminated. Brief Description of Drawings

FIG. 1 is a schematic view of a head-up display showing an embodiment of the present invention.

FIG. 2 is a sectional view showing the embodiment.

FIG. 3 is a side view of a liquid crystal display device showing the embodiment.

FIG. 4 is an explanatory diagram of a display area of the liquid crystal display panel showing the embodiment.

FIG. 5 is a block diagram showing the embodiment.

FIG. 6 is a side view of a liquid crystal display device showing another embodiment.

FIG. 7 is a side view of a liquid crystal display device showing another embodiment.

FIG. 8 is a cross-sectional view showing a conventional example.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The head-up display 11 is placed in the vehicle dashboard 12! /, (See Figure 1). 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 head-up display 11 includes a liquid crystal display device 15, a reflector 16 and the like housed in a housing 17. The liquid crystal display device 15 includes a liquid crystal display panel 18, an illuminator 19 (illumination means), a light guide member 27 (reflection means), and a color sensor 28 (detection means).

[0015] The liquid crystal display panel 18 is a liquid crystal cell in which liquid crystal is sealed in a pair of translucent substrates on which a transparent electrode film is formed, and polarizing plates are attached to both front and rear surfaces, and the vehicle speed is digitally displayed. To do. The illuminator 19 includes a light emitting diode 20 (first light emitting element), a light emitting diode 21 (second light emitting element), circuit boards 22 and 23, condenser lenses 24 and 25, and a dichroic mirror 26 (transmission). Reflection member).

The light emitting diode 20 emits green light L1 (first light), and the eight light emitting diodes 20 are mounted on the circuit board 22. The light emitting diode 21 emits red light L2 (second light), and eight light emitting diodes 21 are mounted on the circuit board 23. The condensing lenses 24 and 25 are made of a translucent resin such as polycarbonate, and are disposed to face the light emitting diode 20 and the light emitting diode 21, respectively. The dichroic mirror 26 is inclined and transmits the green light L1 emitted from the light emitting diode 20. The red light L2 emitted from the light emitting diode 21 is reflected. The liquid crystal display panel 18 is transmitted and illuminated by the illumination light L3 in which the green light L1 and the red light L2 are mixed by the dichroic mirror 26.

[0017] The light guide member 27 is made of a translucent resin such as acrylic, and has a reflecting surface 27a that reflects a part L4 of the illumination light L3. As shown in FIG. 4, the light guide member 27 is arranged at a location where the illumination light L3 can enter from the illumination range S of the illumination light L3 and does not obstruct the display area 18a of the liquid crystal display panel 18. . The color sensor 28 detects the chromaticity of part L4 of the illumination light L3 reflected by the reflecting surface 27a of the light guide member 27, and outputs chromaticity data to a microcomputer to be described later.

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 reflective 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 formed in a body. 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 in a rotatable state together with the holding member 31, and the projection mirror 32 can be rotated by the stepping motor 32 to adjust the projection direction of the display light L. The observer 14 adjusts the angle of the concave mirror 30 by operating a push button switch (not shown) so that the display light is reflected at the position of the eye (that is, the virtual image V can be visually recognized).

The housing 17 accommodates a liquid crystal display device 15 and a reflector 16. The housing 17 is provided with a window portion 44 through which the display light L is emitted. The window 44 has a translucent resin (for example, acrylic) force and has a curved shape. The housing 17 is provided with a light shielding wall 17c to prevent a phenomenon (washout) in which external light such as sunlight enters the liquid crystal display device 15 and the virtual image V becomes difficult to see. The light shielding wall 17c has a flat plate shape and is formed so as to hang obliquely from the top of the housing 17! /. FIG. 5 is a block diagram showing an electrical configuration of the liquid crystal display device 15. A speed sensor 51 detects the speed of the vehicle and outputs speed data to the microcomputer 52. The color sensor 28 outputs chromaticity data to the microcomputer 52. The microcomputer 52 outputs a drive signal to the liquid crystal display panel 18 through the drive circuit 53 to display the vehicle speed on the liquid crystal display panel 18 and also transmits light to the light emitting diodes 20 and 21 through the drive circuits 54 and 55. A drive signal is output, and the light emitting diodes 20, 21 are caused to emit light. The control means 56 comprises a microcomputer 52 and drive circuits 54 and 55. Based on the chromaticity data output from the color sensor 28, the light emitting diode 20 is controlled so that the illumination light L3 has a desired chromaticity. , Adjust the drive voltage applied to 21.

In the present embodiment, the chromaticity of the display light L is set to a desired chromaticity by adjusting the power supplied to the light emitting diodes 20 and 21 based on the chromaticity data output from the color sensor 28. Furthermore, since the color sensor 28 does not block the illumination light L3, the liquid crystal display panel is uniformly transmitted and illuminated.

It should be noted that the present invention can be variously modified without being limited to the present embodiment. For example, as shown in FIG. 6, the color sensor 28 and the light emitting diode 21 are connected to the same circuit board 63. May be installed. Further, for example, as shown in FIG. 7, the light guide member 27 is introduced into the light guide member 27 through the light incident portion 27b that receives a part L4 of the illumination light L3 and the light incident portion 27b. A reflecting surface 27a for reflecting a part L4 of the illumination light L3 toward the color sensor 28, and a light emitting part 27c for emitting a part L4 of the illumination light L3 reflected through the reflecting surface 27a to the color sensor 28 side. The light output part 27c may be configured as a substantially convex lens-shaped condensing part having a spherical shape on the color sensor 28 side. In this way, by providing the light condensing part 27c having a convex lens shape at the portion of the light guide member 27 facing the color sensor 28, the liquid crystal display panel is uniformly transmitted and illuminated, and the illumination light L3 Part of the L4 force S is focused on the central part of the S color sensor 28, so that a sufficient amount of light can be guided to the color sensor 28, and the detection accuracy of the chromaticity detected by the color sensor can be improved. The effect that it can be improved is obtained. Further, in the present embodiment, two types of light emitting diodes 20 and 21 having different emission colors are used. However, for example, three types of light emitting diodes having different emission colors may be used. Industrial applicability

The present invention is applicable to a head-up display that displays a virtual image by projecting display light emitted from a liquid crystal display panel onto a transflective plate called a vehicle windshield or combiner.

Claims

The scope of the claims

[1] A liquid crystal display panel, illumination means for emitting illumination light for illuminating the liquid crystal display panel, detection means for detecting chromaticity of the illumination light, and introducing a part of the illumination light to the detection means A liquid crystal display device.

[2] LCD panel,

A first light emitting element that emits a first light having a first color and a second light emitting element that emits a second light having a second color, the first light and the second light being Illumination means for illuminating the liquid crystal display panel with illumination light including

Reflecting means for reflecting a part of the illumination light;

Detecting means for detecting chromaticity of a part of the illumination light reflected by the reflecting means and outputting chromaticity data;

A liquid crystal display device comprising: control means for adjusting electric power supplied to at least one of the first light emitting element and the second light emitting element based on the chromaticity data.

3. The liquid crystal display device according to claim 2, wherein the reflecting means includes a light guide member having a reflecting surface that reflects the illumination light.

[4] The light guide member according to claim 3, wherein the light guide member includes a condensing unit for condensing the illumination light reflected through the reflecting surface at a portion facing the detection unit. Liquid crystal display device.

[5] The illumination means includes a transmission / reflection member that transmits the first light emitted from the first light emitting element and reflects the second light emitted from the second light emitting element. The liquid crystal display device according to claim 2.

6. The liquid crystal display device according to claim 2, further comprising a circuit board on which the second light emitting element and the detection means are mounted.