JPH11174972A - Liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide a conventional liquid crystal display device, there is no choice but to provide an illuminating device for when the surroundings are dark. Problems had arisen. According to the present invention, a lighting device (6) includes a protective plate / light guide plate (4) provided with a reflection part (4b) on a viewing side surface (4a) of a protective plate of a transparent touch panel (3), and a thickness of the protective plate / light guide plate (4). The light source 5 is opposed to the surface 4c, and the liquid crystal display element 2 is a liquid crystal display device 1 of a reflective type. By having the same function, it is not necessary to provide an illumination device on the back surface of the liquid crystal display element, thereby making it possible to remarkably reduce the thickness and solve the problem.

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 used as a display unit of a portable information terminal device or the like. More specifically, the surroundings are bright in order to reduce battery consumption. In some cases, the display is read by external light,
The present invention relates to a liquid crystal display device configured to read a display by a built-in lighting device when the surroundings are dark.

[0002]

2. Description of the Related Art FIG. 4 shows an example of the structure of a conventional liquid crystal display device 90 of this type. In this liquid crystal display device 90, the rear side of a liquid crystal display element 91 is transparent (transmissive reflection). A plate 92 is provided, and a light guide plate 93 in which a light source 94 such as a cold cathode fluorescent lamp is opposed to a plate thickness surface 93a is provided on the rear surface of the translucent plate 92.

The back surface 93b of the light guide plate 93 is provided with fine linear or dot-like concave or convex portions, and the light incident on the light guide plate 93 from the light source 94 is applied to the front surface 93b.
The light is reflected toward c. The light source 94 is capable of blinking according to the brightness of the surroundings.

[0004] A transparent touch panel 95 as an input means is provided on the viewing direction side of the liquid crystal display element 91. In addition, a press when operating the transparent touch panel 95 is transmitted to the liquid crystal display element 91. A protection plate 96 made of a transparent resin or the like is provided between the liquid crystal display element 91 and the transparent touch panel 95 in order to prevent the display from becoming unclear or from being damaged in an extreme case.

In the liquid crystal display device 90 having the above structure, in a situation where the surroundings are bright, external light entering the liquid crystal display device 90 is reflected by the reflection plate 92 and reaches the viewer to read the display. Therefore, the display can be sufficiently read even when the light source 94 is turned off.
Therefore, the power for turning on the light source 94 is reduced, and the battery life can be extended.

[0006]

However, in the liquid crystal display device 90 having the above-mentioned conventional configuration, a light guide plate 93 must be provided to prepare for a case where the surroundings are dark. It is not much different in thickness and weight from that used as a display unit of a desktop device, and it is sufficiently required as a display unit for a portable device where miniaturization and weight reduction are prioritized. There is a problem that is not satisfied.

On the other hand, when the surroundings are bright, the display is read with reflected light of external light, that is, light transmitted twice through the liquid crystal display element 91, and the liquid crystal display element 91 is used as a reflection type.
In a situation where the surroundings are dark, the display is read with the transmitted light of the light guide plate 93, that is, the light transmitted once through the liquid crystal display element 91, and the liquid crystal display element 91 is used as a transmission type. Therefore, for example, the contrast of the display is different between a bright environment and a dark environment, causing a problem that the display quality deteriorates and gives a sense of incongruity to the user. Had to be an issue.

[0008]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, a transparent touch panel is provided in front of a liquid crystal display element in a viewing direction, and the liquid crystal display element is provided with a transparent touch panel. A liquid crystal display device provided with an illuminating device capable of blinking according to the surrounding brightness at the time of viewing, wherein the illuminating device is linear or dot-shaped on the viewing side surface of the protective plate of the transparent touch panel. A light guide plate also serving as a protective plate provided with a fine concave or convex portion as a reflective portion,
The present invention solves the problem by providing a liquid crystal display device comprising a light source opposed to a plate-thick surface of the protective plate and light guide plate, wherein the liquid crystal display element is of a reflection type. is there.

[0009]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 is a liquid crystal display device according to the present invention. The liquid crystal display device 1 is provided with an illuminating device capable of blinking according to the surrounding brightness during viewing. It is similar to the example.

Also, in the liquid crystal display device 1 of the present invention, the transparent touch panel 3 is provided on the viewing direction side of the liquid crystal display element 2 as in the conventional example. The point that a protection plate is required to protect the liquid crystal display element 2 from pressing when the user operates 3 is also the same as that of the conventional example.

Here, in the present invention, attention is paid to the fact that the necessary and indispensable protective plate is formed of a transparent member made of resin as described above, and the lighting device is utilized by using this protective plate. The light guide plate also serves as a light guide plate, and it is intended to form the light guide plate 4 also serving as a protection plate. To this end, a fine linear surface is formed on the surface 4a on the viewing side of the light guide plate 4 also serving as a protection plate. The reflecting portion 4b is provided as a concave portion (or a convex portion) or a point-like fine concave portion (or a convex portion).

In addition, a light source 5 such as a cold cathode fluorescent lamp or an LED lamp is opposed to the plate thickness surface 4c of the light guide plate 4 also serving as a protective plate, and light is incident on the light guide plate 4 also. Therefore, the light incident from the light source 5 into the protective plate / light guide plate 4 is reflected by the reflecting portion 4b, which is a fine concave or convex portion, provided on the surface 4a on the viewing side to change the traveling direction. Instead, the light reaches the surface 4d on the display element side of the protective plate / light guide plate 4 and is emitted. That is, the illumination device 6 illuminates the liquid crystal display element 2.

FIG. 2 shows the light guide plate 4 also serving as the protective plate.
This is an example of the shape of the reflecting portion 4b provided on the viewing side surface 4a of this embodiment. In this example, one of the reflecting portions 4b is formed as a substantially conical concave portion, and the viewing side surface 4a of the reflecting portion 4b is formed. The distribution state of the liquid crystal display element 2 is adjusted so that the light emitted from the surface 4d on the display element side, that is, the light illuminating the liquid crystal display element 2 has a uniform brightness.

According to the results of trial manufacture and examination by the inventor, the reflecting portion 4b is not limited to the above-mentioned substantially conical concave portion, but as shown in FIG. Concave portion, that is, a groove-shaped reflecting portion 4b, or one not shown may be a substantially conical concave portion, and one may be a substantially V-shaped concave portion, that is, a ridge shape. It has been confirmed that it is good.

Here, the structure of the light guide plate 4 also serves as a light guide plate. First, the function as a light guide plate is such that the larger the size of one of the reflectors 4b, the higher the reflection efficiency. The illumination effect on the liquid crystal display element 2 is improved. On the other hand, as the size of one of the reflection portions 4b is larger, the smoothness of the viewing-side surface 4a is impaired, and the readability of display contents displayed on the liquid crystal display element 2 is reduced.

The inventor also studied this point. As a result, the diameter M and depth D of one reflecting portion 4b and the groove shown in FIG. In the case of the shape (linear concave portion), if both the groove width W and the depth D of one reflecting portion 4b are 0.3 mm or less, the above-described illumination effect is satisfied and the readability is impaired. It was confirmed that it was possible to obtain the light guide plate 4 also serving as a protection plate without any problem.

With the above configuration of the light guide plate 4 also serving as the protective plate, the liquid crystal display element 2 is illuminated by external light from the viewing side when the surroundings are bright and the light source 5 is turned off. Is the same as that of the conventional example, but when the light source 5 is turned on because the surroundings are dark, the light source 5 and the light guide plate 4 also serving as the protection plate,
That is, the light is illuminated from the viewing side by the illumination device 6.

This means that the liquid crystal display element 2 is always used as a reflection type, so that in the present invention, the liquid crystal display element 2 is set to have a high transmittance so as to be suitable for use as a reflection type. What is called a mold is adopted. Therefore, in the liquid crystal display device 1 of the present invention, on the back side of the liquid crystal display element 2, the reflection plate 7 for exclusively reflecting external light and light from the illumination device 6 is provided.

With the configuration described above, the liquid crystal display device 1 of the present invention functions as a reflection type even when the surroundings are bright and when the surroundings are dark. The type and operation mode do not change. Therefore, a change in display quality such as a decrease in contrast due to a change in the operation mode does not occur. In addition, since the light guide plate 4 is also used as the protective plate, the illumination device provided on the back surface of the conventional liquid crystal display element 2 becomes unnecessary, and the liquid crystal display device 1 can be made thinner.

Further, since the liquid crystal display element 2 is dedicated to the reflection type having a high transmittance, the display can be read even with a small amount of external light, and the lighting device 6 needs to be turned on. The situation is reduced and the light source 5 of the lighting device 6 is
As long as a low power consumption device such as an ED lamp can be read sufficiently, the battery life of a portable device employing the liquid crystal display device 1 is further extended.

In actual practice, the transparent touch panel 3 does not necessarily need to be provided on the front surface of the liquid crystal display element 2. For example, if a protective plate for protecting the liquid crystal display element 2 is provided, It is possible to carry out using the protective plate. Further, in order to unify the display quality between the illuminated state and the non-illuminated state, the illuminating device 6 of the present invention may be newly provided on the front surface of the liquid crystal display element 2. , The effect can be expected.

[0022]

As described above, according to the present invention, a lighting device is provided with a light guide plate also functioning as a protection plate having a reflective portion on the viewing side of a protection plate of a transparent touch panel, and a plate of the light guide plate also functioning as a protection plate. The light source is made of a light source facing the thick surface, and the liquid crystal display device is a reflection type liquid crystal display device. By also using the device, it is not necessary to provide an illumination device on the back surface of the liquid crystal display element, and this type of liquid crystal display device used in portable devices can be remarkably thinned. This is extremely effective in reducing the weight and weight.

Secondly, the liquid crystal display element is of a reflective type so that reading of the display is carried out when the lighting device is turned on and when it is not turned on. The operation mode changes between transmissive and reflective when the lamp is not lit, and the display quality changes, such as a decrease in contrast, which caused the user to feel uncomfortable, thereby improving display quality. The effect is extremely excellent.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is an explanatory diagram showing a main part of the same embodiment.

FIG. 3 is an explanatory view showing a main part of another embodiment of the liquid crystal display device according to the present invention.

FIG. 4 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device 2 ... Liquid crystal display element 3 ... Transparent touch panel 4 ... Light guide plate which also serves as a protection plate 4a ... Viewing side surface 4b ... Reflection part 4c ... Plate thickness surface 4d ... Display element side Surface 5 Light source 6 Lighting device 7 Reflector D Reflector depth M Reflector diameter W Reflector groove width

Claims (2)

[Claims] 1. A liquid crystal display comprising a transparent touch panel provided in front of a liquid crystal display element in a viewing direction, and an illuminating device capable of blinking according to the surrounding brightness during viewing. In the display device, the illuminating device is a light guide plate that also serves as a protection plate provided with a linear or dot-like minute concave or convex portion as a reflective portion on the viewing side surface of the protective plate of the transparent touch panel. A liquid crystal display device comprising: a light source facing a plate-thick surface of a light guide plate; and wherein the liquid crystal display element is of a reflection type. 2. The fine unevenness has a width and a depth when formed as a linear concave portion, a width and a height when formed as a linear convex portion,
2. The liquid crystal according to claim 1, wherein each of the diameter and the depth of the point-shaped concave portion and the diameter and the height of the point-shaped concave portion are 0.3 mm or less. Display device.