JPH10123507A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a light transmission quantity to a liquid crystal panel by changing advancing directions of incident lights from various directions in a liquid crystal display device using a transmission type liquid crystal panel. SOLUTION: A liquid crystal panel 2 is provided at the front side of a frame body 1 and a diffusion member 3 is engaged in the lighting window part 1a provided at another side. A reflection plate 4 is incliningly provided in the inside of the frame body and lights entering from the lighting window part are made incident on the liquid crystal panel 2. An optical path changing means 5 acting as a microprism is provided in the inside of the diffusion member 3 to substantially condense incident lights in one direction by changing main advancing directions of the lights. Lights having the changed directions are reflected by the reflection plate 4 to be made straightly incident on the liquid crystal panel 2. Thus, the light transmission quantity of the of the liquid crystal panel 2 is increased. In the optical path changing means 5, projecting lines 5a are provided in the inside of the diffusion member. Or, a means whose inside is divided into plural divisions and in which direction of projecting lines are changed every adjacent division or a means which has pyramide shaped or cone shaped protrusions or the like are adopted as optical path changing means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device for displaying information or the like using a transmission type liquid crystal panel.

[0002]

2. Description of the Related Art When displaying information or the like using a transmissive liquid crystal panel, it is necessary to irradiate light from behind the liquid crystal panel to the front. As for the light irradiation, there is a method in which an illuminating means is used behind the liquid crystal panel,
2. Description of the Related Art In order to save power, a liquid crystal display device has been used in which light from indoor lighting or the like is taken in to brighten a screen.

FIG. 6 is a schematic view of the above-mentioned liquid crystal display device. A transmissive liquid crystal panel 62 is provided on the front surface of a frame 61 having a rectangular cross section, and the other surface of the frame, in the example shown in FIG. A diffusion plate 63 such as a milky white acrylic plate is fitted into the provided lighting window 61a. Inside the frame 61, there is provided a reflection plate 64 for reflecting light rays entering the inside from the daylighting window 61a to brighten the liquid crystal panel.

[0004] This apparatus uses a light beam of a room light as a lighting window 61a.
The light is reflected by the reflection plate 64 to pass light rays from the rear to the front of the liquid crystal panel 62, thereby brightening the display surface of the liquid crystal panel.

[0005]

In the above-mentioned prior art liquid crystal display device, most of the light from the light source for lighting is always radiated toward the liquid crystal panel 62 via the reflector 64. If there is no problem. For example, as shown in FIG. 7, the reflection plate 64 is provided so as to be inclined at 45 ° with respect to the horizontal,
If the light source is provided so as to be directly above the lighting window 61a, the light beam emitted from the light source is the main light beam transmitted through the diffusion plate 63 as shown in FIG. The main reflected light is reflected by the liquid crystal panel 6
2 can be efficiently irradiated. However, such a case is rare in many cases, and in many cases, the light source is located at a position where the main light beam of the reflected light is reflected in a direction other than the liquid crystal panel. Therefore, in such a case, the light source becomes light deflected in the optical path as shown in FIG. 3B, for example, so that the main light beam irradiates a place other than the liquid crystal panel, and the liquid crystal panel becomes too bright. And the LCD panel screen becomes dark.

[0006]

In order to solve the above-mentioned problems, the liquid crystal display device of the present invention is not restricted by the position of the light source due to the use of the light path changing means, and always uses the light source such as a room light or the like. The display surface of the panel is made bright.

Specifically, the optical path changing means changes the traveling direction of light rays incident from various directions through a lighting window provided on the frame, and converges the light substantially in a predetermined direction. Thus, the amount of light transmission of the transmission type liquid crystal panel is increased.

As an example of the optical path changing means, a plurality of ridges are provided in parallel inside a diffusing member attached to a lighting window, so that light rays incident from different directions can be substantially reflected through a liquid crystal panel. There is one that is irradiated.

In another means, the optical path changing means divides the inside of the diffusion member provided in the lighting window into a plurality of sections provided with ridges, and the ridges are adjacent in these sections. The display characteristics of the liquid crystal panel are improved by arranging them in different directions.

In still another means, the display characteristics of a liquid crystal panel are improved by providing a large number of pyramidal or conical projections inside the diffusion member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to the present invention includes a transmissive liquid crystal panel provided on a front surface of a frame, a lighting window provided on another surface of the frame, and a light-receiving window. Optical path changing means for increasing the amount of light transmitted through the liquid crystal panel by changing the traveling direction of light rays incident from various directions and converging light substantially in a predetermined direction. Inside the frame, there is provided a reflecting plate for reflecting the light passing through the lighting window and the light path changing means. The light path changing means changes the traveling direction of the light so that the light reflected by the reflecting plate is transmitted through the transmission type liquid crystal panel. The angle of incidence of the light beam on the reflector changes so that the light beam is incident on the reflector.

Preferably, the optical path changing means changes the traveling direction of the light beam by providing a plurality of ridges inside the diffusion member in parallel.

The light path changing means may divide the inside of the diffusing member into a plurality of sections provided with ridges, and the ridges may be directed in different directions in adjacent sections.

Further, the optical path changing means is provided with a large number of pyramidal or conical projections inside the diffusion member, so that light rays incident from various directions are transmitted therethrough so that the light rays enter the liquid crystal panel. Is also good.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A shows the cross-sectional shape of the present embodiment, and has the same external appearance as that of the above-described conventional technology. That is, the transmissive liquid crystal panel 2 is fitted on the front surface of the frame 1 having a rectangular cross section, and the light-guiding window 1a provided on the upper surface is fitted with the diffusing member 3 made of a diffusing plate such as a milk-white acrylic plate. . A lighting window 1a is provided inside the frame 1.
A reflection plate 4 made of glossy paper or the like for guiding the light taken in from behind to the rear of the liquid crystal panel 2 is mounted diagonally.

The liquid crystal panel 2 is a transmission type liquid crystal panel of a well-known technique, and the display of information such as characters and numerals is controlled by control means (not shown). The liquid crystal panel 2 transmits light from the rear to the front of the liquid crystal panel. , Etc., from the front.

The light path changing means 5 provided on the back surface of the diffusion member 3 changes the traveling direction of light rays incident from various directions through the lighting window 2a to substantially condense light in a predetermined direction. Thus, the amount of light transmitted to the liquid crystal panel 2 is increased. The light path changing means 5 acts as a micro prism, and after the light beam collected from the light-receiving window 1a passes through the diffusion member 3, the main traveling direction changes, and the light reflected by the reflector 4 is reduced as much as possible. LCD panel 2
The rear surface of the diffusion plate is processed so that the angle of incidence of the reflection plate is such that the light is incident on the diffusion plate. Light rays collected from the light-receiving window 1a are diffused by the diffusion member 3, but have a distribution that is biased in the incident direction. That is, this incident direction is the direction of the main light beam. The optical path changing means 5 changes the direction of the main light beam, and in the description in this specification, the traveling direction of light indicates the direction of the main light beam.

The following is an example of the change path changing means 5. The first example is shown in FIG.
As shown in (c), a plurality of ridges 5a having a triangular cross section are provided in parallel inside the diffusion member 3 (the back side of the diffusion plate). The ridge 5a is formed on the entire inner surface of the transparent member 3, and changes the traveling direction of the light beam by a triangular slope.

FIG. 2 schematically shows a state in which the main traveling direction of the light beam is changed by the optical path changing means.
(A) shows a state in which the light source is located directly above the lighting window 1a, so that the light beam goes straight and enters the reflector 4, where it is reflected and the reflected light enters the liquid crystal panel 2. On the other hand, (b) shows an example in which the light source is located at a position that is not directly above the lighting window 1a. Most of the light rays incident on the diffusion member 3 from an oblique direction in the prior art. Is incident on the reflection plate 4 in the incident direction, but in the present invention, the traveling direction of the light beam is changed by the optical path changing means 5 to be incident on the reflection plate and the reflected light is incident on the liquid crystal panel 2. It is incident. Of course, not all of the light taken in from the daylighting window 1a enters the liquid crystal panel 2, but a certain amount of light can always enter the liquid crystal panel regardless of where the light source is located. It is possible to read the information to be performed.

In the first example, the ridge 5 is used as the optical path changing means 5.
a is provided on the entire inner surface of the transparent member, but this focuses on reducing the processing cost. On the other hand, the amount of light incident on the liquid crystal panel varies depending on the position of the light source. It can happen. As a second example, as shown in FIG. 3, the diffusion member 5 is divided into a plurality of sections, and the optical path changing means 15 formed so that the directions of the ridges 15a are different from each other in each of the adjacent sections is provided inside the diffusion member. It is arranged in. This makes it possible to reduce the variation in the amount of light transmitted through the liquid crystal panel due to the change in the position of the light source, because the angle of incidence on the reflector is different for each section, so that the direction of light rays changes in different directions for each section. It was made.

FIG. 4 shows a third example in which the above-mentioned sections are subdivided and arranged in a grid (matrix) in order to further reduce the variation in the amount of transmitted light of the liquid crystal panel. That is, the ridge 25 is provided for each section of the lattice.
The optical path changing means 25 formed so that the direction of a is different,
It is arranged inside the diffusion member so as to reduce the variation in the amount of transmitted light.

Further, the optical path changing means can also achieve the object by providing a plurality of pyramidal or conical projections in addition to the above-mentioned ridges.
FIG. 5 shows, as a fourth example, an example in which an optical path changing means 35 having a large number of quadrangular pyramid-shaped projections (pyramids) 35a arranged in parallel is disposed inside the diffusion member 3, depending on the position of the light source. The liquid crystal panel is characterized in that the light transmittance variation of the liquid crystal panel can be made extremely small.

The optical path changing means and the diffusion plate may be integrally formed, or may be individually formed and installed in combination.

[0024]

According to the present invention, by providing the optical path changing means, the traveling direction of the light incident from various directions through the lighting window is changed and the light is substantially condensed in a predetermined direction to transmit the light. Since the light transmission amount of the liquid crystal panel is increased, the usable place of the liquid crystal display device is not limited, and the information and the like displayed on the liquid crystal panel can always be easily read.

When the light passing through the above-mentioned lighting window and the light path changing means is incident on the liquid crystal panel by changing its traveling direction by the reflector, the light path changing means transmits the light from all directions to the liquid crystal panel. The traveling direction of light can be changed so that reflected light is easily incident on the panel.

Further, if various ridges or protrusions are employed as the optical path changing means, light from various directions incident from the lighting window can be concentrated on the reflection plate, so that the light transmission amount of the liquid crystal panel can be reduced accordingly. It is possible to do more,
The screen of the liquid crystal panel can be brightened.

[Brief description of the drawings]

1A and 1B show a configuration of a main part of a liquid crystal display device of the present invention, wherein FIG. 1A is a sectional view, FIG. 1B is an enlarged sectional view showing an example of a transparent member and an optical path changing unit, and FIG. FIG. 2A is a cross-sectional view taken along line AA of FIG.

FIG. 2 is an explanatory diagram showing a traveling direction of light in the present invention.

FIG. 3 is a sectional view showing a second example of the optical path changing unit.

FIG. 4 is a sectional view showing a third example of the optical path changing unit.

FIG. 5 is a perspective view showing a fourth example of the optical path changing unit.

FIG. 6 is a sectional view of a conventional liquid crystal display device.

FIG. 7 is an explanatory diagram showing a traveling direction of light in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frame 1a Daylighting window part 2 Liquid crystal panel 3 Diffusion member 4 Reflector 5, 15, 25, 35 Optical path changing means 5a, 15a, 25a Protrusion 5b, 5c Section 35a Projection

Claims (5)

[Claims] 1. A transmissive liquid crystal panel provided on a front surface of a frame, a lighting window provided on another surface of the frame, and light beams incident from various directions through the lighting window. A liquid crystal display device comprising: an optical path changing unit that changes a traveling direction and converges light substantially in a predetermined direction to increase a light transmission amount of the transmissive liquid crystal panel. 2. The method according to claim 1, wherein:
A light-reflecting plate that reflects the light beam that has passed through the light-receiving window and the light-path changing means, and the light path changing means changes the traveling direction of the light beam, so that light reflected by the reflecting plate is transmitted through the transmissive liquid crystal. A liquid crystal display device, wherein an incident angle of the light beam on the reflection plate changes so as to be incident on a panel. 3. A liquid crystal display device according to claim 1, wherein said optical path changing means has a plurality of ridges provided in parallel inside the diffusion member. 4. The optical path changing means according to claim 1, wherein the optical path changing means divides the inside of the diffusion member into a plurality of sections provided with ridges, and the directions of the ridges are different in the adjacent sections. A liquid crystal display device characterized by the above-mentioned. 5. The liquid crystal display device according to claim 1, wherein the optical path changing means has a large number of pyramidal or conical projections provided inside the diffusion member.