JPS6019474B2 - lcd clock - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in lamp illumination for liquid crystal watches.

Since the liquid crystal display panel is a light-receiving type, there is a problem that the characters on the display panel cannot be read when the surrounding area is dark.
As a means to compensate for this, a common method is to provide a lamp on the back side of the display panel, guide the light from the lamp to a light guide plate, and diffuse the light from the point light source over the entire surface of the display panel.

In this case, since the scattered light from the light guide plate increases as it approaches the light source, there is a problem that the light is not uniformly scattered from the entire surface of the light guide surface, and the display panel inevitably becomes visible. The present invention changes the scattering surface of the light guide plate according to the amount of light inside the light guide plate, and uniformly scatters the light from the lamp from the entire surface of the light guide plate, uniformly illuminating the display panel and facilitating discussions. This provides an excellent lighting method that is beautiful in appearance. The invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing the principle when a light guide plate scatters light from a lamp. In the figure, the light from a lamp 3 is e.g.
Or follow a route like 20. The light guide plate 2 has a reflective plate 4
A protrusion 5 forming a pattern is integrally formed on the surface facing the . In this case, the description will be made using a convex portion, but the same applies to a concave portion. At this time, the side wall 5 of the protrusion 5
A ray of light incident on point a is directed toward the display panel 1 according to the law of catadioptric refraction. Therefore, light is scattered around the pattern on the light guide plate 2, and the corresponding area on the display panel 1 becomes bright. On the other hand, other light rays 20 are repeatedly reflected inside the light guide plate 2 and proceed further, and are not scattered in this portion. 2nd a
The figure is an explanatory view of a conventional light guide plate, and the pattern 5 provided on the light guide plate 2 is uniform over the entire surface of the light guide plate 2.

However, as explained in FIG. 2b, when the light scattering surface of the light guide plate is uniform, the amount B of light in the light guide plate 2 increases as it is closer to the lamp, and decreases as it is farther from the lamp.

The relationship can be considered to be approximately inversely proportional to the distance from the lamp. This is because the pattern 5 that scatters light is uniform over the entire surface and the scattering characteristic C is constant.Since a large amount of light is scattered near the lamp, the amount of light decreases as you move away from the lamp, and it is inevitable that the light will not be guided. The brightness A obtained by the light scattered from the light plate 2 is non-uniform.

On the other hand, FIG. 3a is a diagram illustrating an embodiment of the present invention, in which patterns 5 that scatter light are arranged densely and densely according to the amount of light in the light guide plate 2. be.

That is, as explained in FIG. 3b, in areas where the amount of light B is large, the pattern 5 is made sparse and the scattering characteristic C is reduced to reduce the amount of scattered light B, so that the amount B of light is reduced slightly. In the part, the pattern 5 is densely arranged to increase the scattering characteristics and increase the amount of scattered light B as much as possible, thereby making the amount of light scattered over the entire surface of the light guide plate 2 uniform and keeping the apparent brightness A constant. This is what I am trying to do. Particularly in the vicinity of the lamp, in addition to the scattered light from the light guide plate, there is direct light from the lamp or reflection from the case, so the unevenness for scattering poses at least no substantial problem. Furthermore, when the unevenness is made denser and denser, the light may become uneven and the presence of the unevenness may become visible, especially in the sparse areas, but the liquid crystal panel is a light-receiving element and does not interfere with reading the time itself. On the other hand, in addition to the method of making the pattern 5 of the light guide plate 2 denser and denser as described above, the amount of scattered light can also be controlled by changing the height of the side wall of the pattern 5, that is, 5a in FIG. can do.

The effect is the same even if the pattern 5 is a convex or concave portion. That is, the amount of unevenness of the pattern 5 of the light guide plate 2 may be changed, or both may be suitably matched. Another example of the pattern 5 is the fourth
Something like the one shown in the figure is also possible.

That is, in FIG. 4, a side reflection layer 6 is formed on the side cross section of the light guide plate 2, except for the part facing the lamp 3, so that the light inside the light guide plate 2 does not escape from the side surface. In such a case, since the amount of light is increased in the peripheral area of the light guide plate 2, the pattern 5 is arranged accordingly. According to the proposal of the present invention, since the liquid crystal display panel is uniformly illuminated when the lamp is turned on, it is possible to obtain sufficiently good visibility even if the lamp is somewhat dark. It is also possible to make the watch thinner, extend battery life, and use batteries other than those for high current output.

Further, in manufacturing the light guide plate 2, if a pattern with varying density or unevenness is applied to the mold during molding, the process can be easily carried out from now on, and there is no problem in carrying out the process. As detailed above, according to the present invention, the liquid crystal display panel is easy to read when the lamp is turned on, has an excellent appearance, and the light from the lamp is effectively utilized. , it is possible to reduce the power consumption, make the watch smaller and thinner, extend the battery life, or avoid the use of special batteries for large force output, and it has excellent effects such as being easy to implement. .

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention. FIG. 2 is an explanatory diagram showing a conventional method. FIG. 3 is an explanatory diagram based on one embodiment of the present invention. FIG. 4 is a drawing showing another embodiment of the present invention. 1...Liquid crystal display panel, 2
...Light guide plate, 3...Lamp, 4...
...Reflector, 5...Pattern, 6...Side reflective layer. Figure 1 Grave 4 Figure 2-o Figure 2-Figure 3-Q Figure 37

Claims (1)

[Claims] 1. In a liquid crystal watch having a liquid crystal display panel, a lamp, and a light guide plate, the light guide plate being disposed opposite to the lower surface of the liquid crystal display panel, the lamp is disposed on a side surface of the light guide plate, and the light guide plate is disposed on a side surface of the light guide plate. The light plate has a flat surface, is formed to reflect incident light on the surface and guide the light, and has a plurality of concave portions or convex portions disposed on at least one of the surfaces for scattering the light, and further includes: A liquid crystal watch characterized in that the concave portions or convex portions are sparsely arranged near the lamp and more densely arranged as they move away from the lamp.