JPH01107236A - Lighting device and display device provided therewith - Google Patents

Abstract

PURPOSE:To execute the uniform lighting of a surface with high luminance and also to prevent sanded texture caused by a dropping impulse test from being caused by making a light scattering body contact in terms of surface with an optical transmitting body through an optical screen and fixing it on the optical transmitting body. CONSTITUTION:A light source 101 is arranged in a hollow part formed in the optical transmitting body 107 and the light scattering body 104 is arranged between the light source 101 and an object to be lighted. The optical transmitting body 107 is formed of a solid body which propagates a light beam 108 projected from the light source 101 to the light scattering body 104 and its hollow part is provided in the effective lighted area E of the object to be lighted. And the light scattering body 104 is made to contact in terms of surface with the light transmitting body 107 through the optical screen 103 and fixed to be in contact with it, so that the light scattering body 104 is not vibrated even in case of accepting the dropping impulse. Thus, the uniform lighting of the surface with high luminance can be executed and also the impulse given to a ferroelectric liquid crystal display panel 106 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lighting device, and particularly to a lighting device that can be applied to a back light source of a display panel using ferroelectric liquid crystal.

(Prior Art) A liquid crystal display panel has a diffused reflection plate arranged on its back surface, and electro-optic modulation of the liquid crystal is identified by the reflected light, or an illumination device is arranged on its back surface, and light rays from the back surface are detected. The display can be identified by controlling the switching operation of the liquid crystal. Generally, the former is called a reflective liquid crystal panel, and the latter is called a transmissive liquid crystal panel. Although reflective liquid crystal panels and transmissive liquid crystal panels each have their own advantages, transmissive liquid crystal panels are particularly suitable for application to display parts of office products.

Until now, a lighting device shown in FIG. 6 has been used in a transmission type liquid crystal panel. In other words, in FIG. 6, two light sources 6
After the - light beams from 01 and 602 are totally reflected on the surface reflection surface 604 and the fine prism reflection surface 605 of the transparent light transmitting body 603, they are emitted from the surface reflection surface 604, and are further transmitted through the light scattering body 606 into diffused light. LCD panel 6
07 can be illuminated from its back.

608 is a light source 601. This is a casing that supports the optical transmission body 603 and the like. Here, two polarizing plates are installed on the upper and lower sides of the liquid crystal panel 607, but these are not shown. Also, the liquid crystal panel 6
The driving circuit board and fixing members connected to 07 are omitted.

However, in the lighting device 600 using such a light transmission body 603, the luminous flux utilization rate from the light sources 601 and 602 is very low, and a large amount of power is required to brightly illuminate the liquid crystal panel 607. Since the light from the light sources 601 and 602 is spread radially, the light sources 601 and 60
2, the amount of light emitted from the optical transmission body 603 is large, and at a position far from the light sources 601 and 602, the optical transmission body 60
There was a problem in that the amount of light emitted from 3 was small and it was difficult to provide uniform surface illumination.

For this reason, conventionally, a lighting device shown in FIG. 7 has been used.

That is, in FIG. 7, the light reflector 702 is made of, for example, a film having a mirror surface, and in order to increase the luminous flux utilization rate,
The light source 701 is installed on the inner wall of the housing 705 so as to surround it. Further, 703 is an optical screen made of a polyester film on which dot-shaped opaque bodies are provided, for example, by vapor deposition or printing. A density distribution is formed.

A portion A of the light beam emitted from the light source 701 directly reaches and passes through the optical screen 703, becomes scattered light by the light scatterer 704, and illuminates the liquid crystal panel 706 from the back side thereof. Moreover, after the other part B of the light beam is reflected by the light reflector 702,
The light ray B reaches the optical screen 703 and finally passes through the light scatterer 704 and is emitted as scattered light. Here, since the light rays emitted from the light source 701 spread radially around the light source 701, the luminous flux density reaching the optical screen 703 differs depending on the position within the incident plane of the optical screen 703. Therefore, by forming a density square in the opaque body part provided on the light screen 703, the light scattering body 704
The density of the luminous flux incident on the surface becomes uniform, and a surface light source without uneven brightness can be obtained.

In addition, in this device, most of the light rays emitted from the light source can be used, except for a part of the light rays being blocked by the opaque portion of the optical screen 70'3, so a high-intensity surface light source is possible. Furthermore, by increasing the number of light sources 701, a large-area surface light source can be obtained, which is suitable as a back light source for a large liquid crystal panel.

(Problems to be Solved by the Invention) By the way, the ferroelectric liquid crystal panel disclosed by Clark et al. in U.S. Pat. No. 4,367,924 enables a large-area liquid crystal display. According to , after fixing the ferroelectric liquid crystal panel 706 to the illumination device 700 in FIG. 7, does it fall? When an L'X test was performed, it was found that orientation disturbance (hereinafter referred to as sanded texture) clearly caused switching failure. FIG. 8 shows a structure in which a ferroelectric liquid crystal panel 706 is mounted on the conventional lighting device 700 shown in FIG. This is the shock waveform when dropped. Figure 8(a)
81 is an impact acceleration waveform that the bottom surface 705-1 of the lighting device 700 receives, and the peak value is 01, which is the same as the set acceleration G1 of the drop tester, but the ferroelectric liquid crystal panel 70
On the central surface 708-1 of No. 6, the waveform was doubled to 2G1 as shown in the waveform 82 in FIG. 8(b), and the orientation was disturbed and a sanded texture appeared. That is, this lighting device 70
0, the four sides 704-1, 70 around the light scatterer 704
4-2 (direction perpendicular to the page is not shown) is the only housing 705
The center part is neutral when it is fixed to . Therefore, when the conventional lighting device 700 is dropped in the Z direction in FIG.
The light scattering body 704 vibrates due to the impact of the fall, and therefore, the southern acceleration applied to the liquid crystal panel 706 on the light scattering body 704 increases as shown by waveform 82 in FIG. 8(b).

Therefore, an object of the present invention is to provide a lighting device that solves the above-mentioned problems and a display device using the same.

(Means for Solving the Problems) That is, the present invention provides an illumination device that includes a light source and a light scattering body and illuminates an illuminated object from the back, in which the light source is disposed in a hollow part formed in a light transmission body. The light scattering body is disposed between the light source and the object to be illuminated, and the light transmission body is formed of a solid body that propagates light rays emitted from the light source toward the light scattering body. The present invention is characterized by a lighting device in which the hollow portion is provided within an effective lighting area of an object to be illuminated, and a display device using the same.

According to the present invention, it is an object to provide an improved illumination device that can perform high-intensity and uniform surface illumination and does not cause sanded texture in a 2U drop impact test, and a display panel using the same. becomes possible.

(Example) Hereinafter, an example of a lighting device according to the present invention will be described according to the drawings. FIG. 1 is a sectional view of a lighting device of the present invention and a display panel using the same. The light transmitting body 107 is made of a transparent or semi-transparent material such as polymethyl methacrylate (PMMA) or glass, and has a groove or a hole as a hollow part in which the light source 101 is installed. Next, the light reflector 102 is made of a film with a mirror surface, such as aluminum.

It is obtained by forming a film of metal such as chromium or silver using a vapor deposition method. The light reflectors 102 are provided on the end faces of the light transmitting body 107 except for the light output surface, and are fixed to each other via an adhesive. Furthermore, the housing 105 is also fixed to each other, and as a result, the optical transmission body 107 and the housing 105 are fixed to each other. The optical screen 103 is made of a polyester film on which point-shaped opaque bodies are provided, for example, by vapor deposition or printing, and the opaque bodies have a density distribution in order to make the distribution of the luminous flux emitted from the light transmission body 107 to the optical screen 103 uniform. has. Further, the optical screen 103 is connected to the optical transmission body 107.
It is in surface contact with the light emitting surface of the light emitting surface and is tightly fixed by adhesive.

The light scattering body 104 can be formed of a milky white translucent material, and in particular, roughened PMMA, a glass plate, or PMMA containing crystalline high refractive index particles can be used. Further, a light scatterer 104 and a light screen 10
3 is in surface contact with the light transmitting body 307 and is fixed to the light transmitting body 107 by adhesive or other means.

Next, the illumination device 10 shown in FIG.
The operation of 0 will be explained. For example, liquid crystal display panel 1
A part of the light rays 108 emitted from a long light source 101 such as a fluorescent lamp disposed within the effective illumination area E of 06 propagates within the light transmission body 102, and the other light rays 109 propagate through the light reflection body. After being reflected at 102, it propagates within the optical transmission body 102,
The light diffuser 104 receives appropriate attenuation by the light screen 103.
, and becomes diffused light that illuminates the liquid crystal display panel 106 from behind.

According to this embodiment, there are the following advantages. That is,
Since the light scattering body 104 is closely fixed in surface contact with the light transmitting body 102 through the optical screen 103, the falling f
Even when receiving fTl1, the light scattering body 104 does not vibrate, and no excessive impact acceleration is applied to the liquid crystal panel 106.

FIG. 2 shows a shock waveform when the ferroelectric liquid crystal panel 106 is mounted on the lighting device 100 of this embodiment and a drop test similar to that shown in FIG. 8 is performed. The impact acceleration waveform 22 received by the central surface 106-1 of the ferroelectric liquid crystal panel 106 shown in FIG. 2(b) corresponds to the set acceleration Gl of the drop tester (impact acceleration waveform 21) shown in FIG. 2(a). , and no sanded texture occurred in the ferroelectric liquid crystal panel 106. Also, as a matter of course, the LCD panel 1
06 is floated upward away from the light scattering body 104, it is necessary to support and fix the periphery of the bottom surface of the liquid crystal panel 106 by other means. When this occurs, excessive impact acceleration is applied to the liquid crystal panel 106, causing a sanded texture to appear.

The liquid crystal panel 106 used in the present invention is disclosed in US Pat.
36.7924, U.S. Pat. No. 4,639,089, U.S. Pat. A great effect can be exerted on ferroelectric liquid crystal panels whose film thickness is set to be sufficiently thin to eliminate the helical structure inherent in smectic liquid crystals. Such ferroelectric liquid crystal panels are designed to have a cell thickness of approximately 0.5 μm to 2 μm, which is extremely thin, and there is a problem in that alignment holes such as sanded texture are likely to occur especially when subjected to impact. This problem could be solved by using a lighting device.

FIG. 3 shows a second embodiment of the invention. This is an example in which the present invention is applied to the first embodiment shown in FIG. 1, in which the shape of the reflector is made into a curved surface in order to obtain a lighting device with even higher brightness.

In the figure, the same reference numerals as in FIG. 1 represent the same members. In this embodiment, the light reflector lower surface 302-1 is not horizontal. FIG. 4 is a cross section taken along line C-C in FIG. 3, and shows the lower surface 305-
1 is provided with a plurality of protrusions 305-2,
The shape of the lower surface 3°5-1 of the casing has a structure that is not easily deformed even by impact force in the Z direction. Therefore, the light scattering body 104 does not vibrate even if it receives a drop impact, and no excessive impact acceleration is applied to the liquid crystal panel 106. Here, the protrusions 305-2 are not structured independently one by one,
There is no problem with a filling structure in which the bottom surface of the casing lower surface 305-1 is in contact with the floor surface.

[Other Examples]

FIG. 5 shows another embodiment in which the optical screen 103 used in the embodiment of FIG. 1 of the present invention is formed integrally with the optical transmission body 107. The light transmitting body 501 is a transparent or semitransparent body having a light scattering surface 502, and is formed of PMMA, a glass body, or PMMA containing crystalline high refractive index particles. Since the light scattering surface 502 has a distribution in the degree of light scattering, the density of the light flux emitted to the light scatterer 104 can be uniformly controlled, and it can also function as the optical screen 103. According to this embodiment, another advantage arises in that the number of parts can be further reduced than in the first embodiment. Further, this embodiment can also be applied to the first and second embodiments.

In the above embodiments, a ferroelectric liquid crystal panel was used as the liquid crystal panel, but the invention is not limited to this.
The present invention is also effective for nematic liquid crystal panels.

Further, although only an example in which two light sources are used has been described, one light source may be used, and the same effect can be obtained even when three or more light sources are used. When three or more light sources are used, it is possible to provide a liquid crystal panel illumination device having a larger area than when two light sources are used.

(Effects of the Invention) According to the device of the present invention, the impact applied to the ferroelectric liquid crystal panel can be significantly reduced compared to conventional devices while maintaining the performance of providing high-intensity and uniform surface illumination. This makes it possible to provide an excellent area illumination device that does not cause alignment defects such as sanded texture.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a lighting device of the present invention and a display device using the same. FIG. 2 is a characteristic diagram of the waveform of a drop shock received by a display panel when using the apparatus of the present invention. FIG. 3 is a cross-sectional view of another lighting device of the present invention and a display device using the same, and FIG. 4 is a cross-sectional view taken along the line C-C. FIG. 5 is a cross-sectional view of another device of the present invention. 6 and 7 are cross-sectional views of a conventional lighting device and a display device using the same. FIG. 8 is a characteristic diagram of a waveform of a drop shock received by a display panel when using a conventional device. Cθ)
(Shinra9u+1bu0I7-1- Thu r71

Claims (12)

[Claims] (1) In a lighting device that includes a light source and a light scattering body and illuminates an illuminated object from the back, the light source is disposed in a hollow part formed in a light transmission body, and the light scattering body is arranged between the light source and the illuminated object. and the light transmitting body is formed of a solid body that propagates the light beam emitted from the light source toward the light scattering body, and the hollow part is located within the effective illumination area of the illuminated body. A lighting device comprising: (2) The lighting device according to claim 1, wherein the light exit surface of the light transmitting body is a light scattering body. (3) The lighting device according to claim 1, wherein the light transmitting body and the light scattering body are arranged independently. (4) The light transmitting body and the light scattering body are arranged independently, and a light screen having an opaque part is closely fixed between the light transmitting body and the light scattering body. The lighting device according to item 1. (5) The light transmission body, the light source, and the light scattering body are supported by a housing, and the lower surface of the housing is formed into a tapered or curved shape and is provided with a plurality of protrusions. The lighting device according to item 1. (6) The lighting device according to claim 1, wherein the number of the light sources is one or two or more. (7) A display device including a lighting device and a display panel, wherein the lighting device includes a light source, a light scattering body, and a light transmission body, and the light source is arranged in a hollow part formed in the light transmission body, The light scattering body is disposed between the light source and the display panel, and the light transmission body is formed of a solid body that propagates the light rays emitted from the light source toward the light scattering body, and 1. A display device characterized by illuminating from. (8) The display device according to claim 7, wherein the display panel includes an optical modulation substance. (9) The display device according to claim 8, wherein the optical modulating substance is a liquid crystal. (10) The display device according to claim 9, wherein the liquid crystal is a ferroelectric liquid crystal. (11) The display device according to claim 10, wherein the ferroelectric liquid crystal is a chiral smectic liquid crystal. (12) Claim 11, wherein the film thickness of the chiral smectic liquid crystal is set to such a thickness that the helical structure inherent in the chiral smectic liquid crystal disappears in the absence of an electric field.
Display device as described in section.