JPH04269718A - LCD display with backlight - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display device using the back light of simple constitution whose size and shape can freely be selected. CONSTITUTION:The liquid crystal display device consists of a liquid crystal element 1 and polarizing plates 2 and 3. A fluorescent-agent containing transparent plate 4 which is irradiated by a light source 6 is arranged on its reverse surface. The fluorescent agent in the transparent plate is excited with the incident light from the light source 6 to emit fluorescent light, so that the transparent plate serves as the back light of the liquid crystal display device. A reflecting plate 5 is also provided.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a liquid crystal display device, in particular,
The present invention relates to a liquid crystal display device with a backlight.

0002

[Prior Art] Conventionally, a transmissive liquid crystal display (LCD)
requires illumination light from behind the liquid crystal display, and typically has a built-in light source as a so-called backlit liquid crystal display.

The light source of such a backlit liquid crystal display device includes a flat light source such as an EL board or a flat LED, a fluorescent tube used as a side light, or a point light source such as a light bulb or LED. It is known that a light source similar to that used as a side light is used.

[0004] Since EL plates generally require an AC power supply of 50 V or more, they are unsuitable for small-sized liquid crystal display devices. There is also the problem that the shape of the EL plate must be made to match the liquid crystal display device. Planar LEDs do not have the problem of power supply, but like the EL board, they have the problem of having to create a shape that matches the liquid crystal element. Those that use fluorescent tubes require a high voltage power supply.
Furthermore, since it is difficult to obtain fluorescent tubes of any size in small-volume production, it is not possible to make the display device have a variety of sizes. Sidelights that use a light source similar to a point light source, such as a light bulb or LED, have a simple structure and require a low voltage power supply, so they are suitable for liquid crystal display devices. Therefore, there is a problem that the lighting effect is small. Therefore, none of the conventional backlights could be said to be sufficient.

[0005]

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and provides a liquid crystal display device using a backlight which has a simple structure and whose size and shape can be freely selected. The purpose is to provide

[0006]

[Means for Solving the Problems] The present invention provides a backlit liquid crystal display device including a transmission type liquid crystal display device, a fluorescent agent-containing transparent plate disposed behind the liquid crystal display device,
It is characterized by having a light source arranged so that light enters the fluorescent agent-containing transparent plate from the lateral direction.

[0007]

[Operation] When light enters a transparent plate containing a fluorescent agent, the fluorescent agent emits light and emits light from the entire surface. Therefore, by allowing light to enter from the side of the fluorescent agent-containing transparent plate, the entire transparent plate acts as a surface light source and becomes a backlight for the liquid crystal display device.

[0008] It is easy to obtain a fluorescent agent-containing transparent plate of an appropriate size. For example, when using acrylic resin, a fluorescent agent-containing transparent plate of any size can be obtained by cutting or machining. Obtainable.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view schematically showing a backlit liquid crystal display device of the present invention. In the figure, 1 is a liquid crystal element,
2 and 3 are polarizing plates, 4 is a transparent plate containing fluorescent agent, 5 is a reflective plate,
6 is a light source, and 7 is an arrow indicating the viewing direction. Liquid crystal element 1
In this embodiment, since a TN type liquid crystal is used, polarizing plates 2 and 3 are arranged on the upper and lower surfaces.

Light incident on the lower polarizing plate 3 is provided from a transparent plate 4 containing a fluorescent agent. Light is made incident from the side of the fluorescent agent-containing transparent plate 4 by a light source 6. The transparent plate itself acts as a light guide and introduces the incident light from the light source 6 into the transparent plate. The fluorescent agent within the transparent plate is excited by the introduced light and emits fluorescence. As the light source 6, an appropriate light emitting source such as a light bulb or an LED can be used, but the requirement is that it can excite the fluorescent agent.

[0011] Although the reflection plate 5 is not necessarily required, by providing it, the amount of illumination light to the liquid crystal display device can be further increased.

[0012] As the fluorescent agent-containing transparent plate, a fluorescent acrylic plate or the like can be used. Since the acrylic plate has high light transmittance, it can be said that it is a suitable material for the present invention.

[0013] Since the fluorescent agent-containing transparent plate can emit light even with external light, it is recommended that the external light be introduced by incident light from the viewing direction or from the side of the fluorescent agent-containing transparent plate 4. If you do so, it is also possible to obtain the effect of a backlight using external light.

[0014] By using a colored transparent plate or a phosphor with an appropriate emission color, it is also possible to obtain light emission corresponding to the color.

[0015]

As is clear from the above description, according to the present invention, it is possible to obtain a backlight light source of any size and shape with a simple configuration, and in particular, it is possible to configure a small liquid crystal display device. There is an effect that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing a backlit liquid crystal display device of the present invention.

[Explanation of symbols]

1 Liquid crystal element 2, 3 Polarizing plate 4 Transparent plate with fluorescent agent 5 Reflector plate 6. Light source

Claims (1)

[Claims] 1. A transmissive liquid crystal display device, a transparent plate containing a fluorescent agent disposed behind the liquid crystal display device, and a light source disposed so that light enters the transparent plate containing the fluorescent agent from the side direction. A backlit liquid crystal display device comprising: