JPH0511249A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce the power consumption required for a light emission body and to prolong the life of the light emission body by providing a means which guides external light in from the other side end surface, which crosses a side end surface for guiding the light from the light emission body at right angles, except from the light emission body. CONSTITUTION:This liquid crystal display device is equipped with the light emission body 6 which is supplied with electric power to emit light, a light guide plate 3 which guides the light from this light emission body 6 in from one side end surface and diffuses and emits the light from its main surface, and a liquid crystal display substrate 4 which is positioned on the main surface side of the light guide plate 3. In this case, this device is provided separately with the means which guides the external light in from the other side end surface, crossing one side end surface of the light guide plate 3 at right angles, except from the light emission body. Further, the device is equipped with a means which cuts off only the electric power supplied to the light emission body 6. If the device is irradiated with the sunshine or interior illumination light in its use place, the light is guided in from the new flank of the light guide plate 3 and diffused and emitted from the main surface on the side of the liquid crystal display substrate. Consequently, the external light except from the light emission body is only guided in, so an electrode for supply to the light emission body can be made small correspondingly.

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,
In particular, it relates to a so-called backlight type liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device of this type is, for example, an E
A light emitter such as L, LED, or CFL that emits light by supplying electric power is built in.
It is positioned close to one side surface of the light guide plate arranged on the back surface of the liquid crystal display substrate (liquid crystal panel).

In the light guide plate, a reflection sheet is arranged on the surface opposite to the main surface facing the liquid crystal display substrate, and a reflection tape is attached to the side end surface other than the side end surface on which the light emitting body is positioned. It has been done.

As a result, the light from the light emitting body passes through the inside of the light guide plate, is irradiated from the main surface and is transmitted through the liquid crystal display substrate.

[0005]

However, in the liquid crystal display device having such a structure, when the liquid crystal display is driven, the built-in light emitting body is always supplied with electric power to emit light. It was something that

Therefore, the power consumption of the light emitter is large,
There is also a problem that the life of the light emitting body is shortened.

In particular, in recent years, a portable type so-called laptop type has also appeared, and there is a type that uses a rechargeable battery as its power source, and it is demanded that the power consumption can be greatly reduced. Is coming.

Therefore, the present invention has been made under such circumstances, and an object of the present invention is to reduce the power consumption required for a light emitting body used as a backlight, and the light emitting body. An object of the present invention is to provide a liquid crystal display device having an improved life.

[0009]

In order to achieve such an object, the present invention basically provides a light emitting body which emits light by supplying electric power, and one end face for emitting light from the light emitting body. In a liquid crystal display device including a light guide plate that diffuses and emits from the main surface of the light guide plate and a liquid crystal display substrate that is positioned on the main surface side of the light guide plate, from the other side end surface orthogonal to the one end surface of the light guide plate It is characterized in that it is provided with means for taking in external light other than the light-emitting body.

Further, the above-mentioned structure is characterized in that means for cutting off only the electric power supplied to the light-emitting body is provided.

[0011]

The liquid crystal display device having the above-described structure can receive sunlight (or indoor illumination light, for example) in a place where it is used.
In the case where the light is emitted, the light can be taken in from the side surface of the light guide plate and diffused and emitted from the main surface on the liquid crystal display substrate side.

Therefore, it is possible to reduce the electric power supplied to the light-emitting body by the amount of external light other than the light-emitting body taken in.

Therefore, the power consumption of the light emitting body can be reduced and the life can be extended.

Further, when the brightness of the liquid crystal display device is not so required, the above effect can be enhanced by cutting off the power supplied to the light emitting body.

[0015]

FIG. 3 is a constitutional view showing an embodiment of a liquid crystal display device according to the present invention, and is an exploded perspective view showing a liquid crystal display module in particular.

In FIG. 1, first, there is a printed circuit board 1, and a drive circuit (not shown) for driving a liquid crystal display substrate is mounted on the printed circuit board 1.

A signal is input to the drive circuit via the inner connector 2.

A light guide plate 3, which will be described in detail later, is arranged on the upper surface of the printed circuit board 1. A fluorescent tube 6 is positioned on one end surface of the light guide plate 3, and a reflection sheet 7 is used so that all light from the fluorescent tube 6 is incident on the one end surface of the light guide plate 3. Is covered.

A liquid crystal display substrate (liquid crystal display panel) 4 is arranged on the upper surface of the light guide plate 3.

Further, a frame 5 is arranged on the upper surface of the liquid crystal display substrate 4. This frame 5
Exposes an effective display area excluding the periphery of the liquid crystal display substrate 4, and can be crimped onto the printed circuit board 1.

FIG. 4 is a perspective view showing the construction of the above-mentioned printed board 1, light guide plate 3, liquid crystal display board 4, frame 5, etc., which constitutes a liquid crystal display module.

FIG. 1 is a constitutional view showing an embodiment of the light guide plate 3, in which FIG. 1 (a) is a plan view and FIG. 1 (b) is a side view.
(C) is a bottom view. A sectional view taken along the line II-II in FIG. 1 is shown in FIG.

As shown in FIG. 2, the light guide plate 3 is made of an acrylic plate 10. The surface (main surface) of the acrylic plate 10 opposite to the liquid crystal display substrate 4 is shown in FIG. As shown, the diffusion plate 11 and the reflection sheet 12 are arranged.

The diffuser plate 11 is, for example, a polyester plate with a fine white dot-like printed pattern formed on the surface thereof, and is arranged over the entire area of the light guide plate 3 except for the upper part thereof.

Here, a region of the light guide plate 3 where the diffusion plate 11 is arranged is a region where the liquid crystal display substrate 4 is positioned, and a region surrounded by a dotted line in the drawing is an effective region of the liquid crystal display substrate 4. Corresponds to the display area.

The reflecting sheet 12 is arranged on the light guide plate 3 and is attached to the light guide plate 3.
The reflecting surface of the reflecting sheet 12 is on the side in contact with the light guide plate 3.

On the back surface of the light guide plate 3, a reflection sheet 13 is attached over the entire area, and even in this case, the reflection surface is the side abutting on the light guide plate 3.

One end surface (the left side end surface in the drawing) of the light guide plate 3 is slightly extended in a portion where the diffusion plate 11 is arranged, compared with a portion where the reflection sheet 12 is arranged. The fluorescent tube 6 is arranged on the side end surface of the extending portion.

The fluorescent tube 6 is fixed to the light guide plate 3 by rubber bushes 15 attached to both ends of the fluorescent tube 6 with a slight distance from the side end surface.

Further, there is a reflection sheet 7 that covers the fluorescent tube 6 and has both ends attached to the main surface and the back surface of the light guide plate 3, respectively. With this reflective sheet 7, the fluorescent tube 6 is provided.
All the light from is incident on the side end surface of the light guide plate 3.

A white tape 16, for example, is attached to the other side end face opposite to the side end face so that the incident light in the light guide plate 3 does not pass through as it is.

A white tape 17 is also attached to the side end surface of the light guide plate 3 at the lower end.

The side end face of the acrylic plate 10 is exposed at the other side end face opposite to the side end face to which the tape 17 is attached, and the exposed face is an arc from the main surface to the back surface of the light guide plate 3. Forming a shape.

The exposed portion of the acrylic plate 10 is a portion on which external light other than the light from the fluorescent tube 6 is made incident, and a large amount can be obtained by forming the lens with the arc shape. It is possible to take in the outside light of.

FIG. 5 is a diagram showing the external configuration of the microcomputer 20 in which the liquid crystal display module shown in FIG. 4 is incorporated. In this case, the acrylic plate 10 exposed at the upper end of the light guide plate 3 is exposed from the outer frame case 22 of the liquid crystal display unit 21 of the microcomputer 20.

The liquid crystal display unit 21 is provided with a switch 23 that simply shuts off the power supply to the fluorescent tube 6. Even if the switch 23 is turned off, the computer itself is driven, The display device itself is still driven.

With the configuration as in the above-described embodiment, when sunlight (or illumination light in a room) is irradiated at the place where the microcomputer 20 is used, the light is guided by the light guide plate 3. Can be taken in from the side surface (exposed surface of the acrylic plate 10) and diffused and emitted from the main surface on the liquid crystal display substrate 4 side.

Therefore, the power supplied to the fluorescent tube 6 can be reduced by the amount of outside light other than the fluorescent tube 6 that is taken in.

Therefore, the power consumption of the fluorescent tube 6 can be reduced and the life can be extended.

When the brightness of the liquid crystal display section 21 is not so high, the above-mentioned effect can be enhanced by shutting off the power supplied to the light emitting body by operating the switch 23. it can.

In the above-described embodiment, the exposed portion of the acrylic plate 10 in the light guide plate 3 has an arc shape as shown in FIG. 2, but the exposed portion has a flat shape as shown in FIG. It goes without saying that the effect can be obtained. Also, it may have another shape.

In the above-described embodiment, the side end surface of the acrylic plate 10 constituting the light guide plate 3 is directly exposed from the outer frame case 22 of the liquid crystal display section 21, but FIG.
As shown in FIG. 5, the flexible light guide member 30 is extended from the side end surface of the acrylic plate 10, and the liquid crystal display unit 21
Of course, external light may be taken in from a desired portion of the outer frame case 22.

In the above-mentioned embodiments, the case where the liquid crystal display device according to the present invention is applied to a microcomputer has been described, but the invention is not limited to the microcomputer and may be applied to a word processor or the like. Needless to say.

In this embodiment, the case where the fluorescent tube is used as the light emitting body used as the backlight has been described, but it goes without saying that EL or ELD may be used.

[0045]

As described above, according to the liquid crystal display device of the present invention, it is possible to reduce the power consumption of the light emitting body used as a backlight and to extend the life of the light emitting body.

[Brief description of drawings]

1A to 1C are configuration diagrams showing an embodiment of a liquid crystal display device according to the present invention, in particular, an embodiment of a light guide plate.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an exploded perspective view showing an embodiment of a liquid crystal display module in the liquid crystal display device according to the present invention.

FIG. 4 is a perspective view showing an embodiment of a liquid crystal display module in the liquid crystal display device according to the present invention.

FIG. 5 is an external configuration diagram showing an embodiment of a microcomputer to which the liquid crystal display device according to the present invention is applied.

FIG. 6 is a sectional view showing another embodiment of the liquid crystal display device according to the present invention.

FIG. 7 is a perspective view showing another embodiment of the liquid crystal display device according to the present invention.

[Explanation of symbols]

3 ... Light guide plate, 4 ... Liquid crystal display substrate, 6 ... Fluorescent tube, 10 ... Acrylic plate, 11 ... Diffusion plate, 12 ... Reflection sheet.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masanori Okawa             Hitachi, Ltd. 3300 Hayano, Mobara-shi, Chiba             Mobara Factory (72) Inventor Haraguchi             Hitachi, Ltd. 3300 Hayano, Mobara-shi, Chiba             Mobara Factory (72) Inventor Masakatsu Okamoto             Hitachi, Ltd. 3300 Hayano, Mobara-shi, Chiba             Mobara Factory

Claims (2)

[Claims] 1. A light-emitting body that emits light when power is supplied, a light guide plate that takes in light from the light-emitting body from one end face and diffuses and emits the light from a main surface, and a liquid crystal positioned on the main surface side of the light guide plate. A liquid crystal display device comprising a display substrate, characterized in that the liquid crystal display device further comprises means for taking in external light other than the light-emitting body from another side end surface of the light guide plate which is orthogonal to the one end surface. 2. The liquid crystal display device according to claim 1, further comprising means for cutting off only electric power supplied to the light emitting body.