JPH11184388A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the display quality by improving the reading easiness a display by lighting it with uniform lightness since light not reflected by the surface of a front glass plate and the arrangement of a reflection part is optimized. SOLUTION: The reflection type liquid crystal display device 1 has its lighting device 3 composed of a light source 4 provided on the end surface 21a of a glass substrate 21 on the view-directional side of a liquid crystal display element 2 and a light control layer 5 which is formed on the surface 21b on the view- directional side of the glass substrate 21 of a transparent member having the same refractive index and provided with fine linear reflection parts 5a on the surface on the view-directional side, so the light from the light source 4 is made incident on the glass substrate 21 and propagated and the light is reflected by a reflection part 5a provided at a proper position for lighting, thereby lighting the display with uniform lightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device which is used as a display portion of a relatively small device such as a wristwatch, a portable telephone, a portable information terminal, a portable game machine, and the like. More specifically, the present invention relates to a device in which an illuminating device is provided in the reflective liquid crystal display device in preparation for darkness such as at night.

[0002]

2. Description of the Related Art A conventional reflection type liquid crystal display device 90 of this kind
FIG. 5 shows an example of the configuration of
D, a light source 91 such as a cold cathode fluorescent lamp was used to illuminate the liquid crystal display element 92 from the viewing direction side. At this time, since the light source 91 is arranged outside the display surface 92a of the liquid crystal display element 92 so as not to block the display, the illumination is performed from an oblique direction. Is also required to be smaller and thinner,
The light source 91 is usually provided close to the display surface 92a, and therefore, the angle α at which the illumination light reaches the display surface 92a tends to be small.

[0003]

However, in the above-mentioned conventional reflection type liquid crystal display device 90, first, since the angle α at which the illumination light reaches the display surface 92a is small, the liquid crystal display element Light that does not reach the inside and is reflected on the surface increases, and the reflected light shines on the display surface 92a, which causes a problem that reading becomes difficult to read.

Second, since the display surface 92a is directly illuminated by the light source 91, as the distance from the light source 91 increases, the display surface 92a becomes darker in inverse proportion to the square of the distance. There is a problem that the brightness is not uniform and the brightness is not uniform so that reading is difficult.

Third, since the light is incident on the liquid crystal display element 92 from an oblique direction, as shown in FIG. In contrast, this causes the image at the incident position and the image at the emission position to appear to be overlapped with each other, thereby causing a problem such that a double image is generated and reading of the display becomes difficult. Was to be done.

[0006]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, there is provided a reflection type liquid crystal display device provided with an illuminating device for preparing for darkness. A light source provided on an end surface of a glass substrate on the viewing direction side of the display element; and a transparent member having a refractive index substantially the same as that of the glass substrate on a surface on the viewing direction side of the glass substrate. An object of the present invention is to solve the problem by providing a reflective liquid crystal display device comprising a light control layer provided with a fine line-like or dot-like reflective portion on a surface on the direction side.

[0007]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 and FIG.
Is a reflection type liquid crystal display device according to the present invention,
This reflection type liquid crystal display device 1 is the same as the conventional one in that an illumination device 3 is provided on the liquid crystal display element 2 in preparation for use in a dark place.

In the present invention, the illuminating device 3 is composed of a light source 4 and a light control layer 5.
A light source such as a light bulb, an LED, or a cold cathode fluorescent lamp is provided on an end face 21 a of a glass substrate 21 (hereinafter, referred to as a front glass substrate 21) on the viewing direction side of the liquid crystal display element 2. Is introduced into the front glass substrate 21, and the light control layer 5 is provided in close contact with a surface 21 b (hereinafter referred to as a surface 21 b) of the front glass substrate 21 on the viewing direction side.

The one light control layer 5 is formed of a transparent resin member. In this embodiment, the light source 4 is disposed on the surface of the light control layer 5 on the viewing direction side. As shown in FIG. 2, a plurality of groove-shaped reflecting portions 5a having a substantially V-shaped cross section are provided in a line shape in a direction substantially parallel to the formed end surface 21a.

At this time, since the reflection portion 5a is provided on the display surface 2a of the liquid crystal display element 2, it is required that the reflection portion 5a be fine in order not to make the display difficult to read. According to the inventor's examination of a prototype for realizing the present invention, the groove width W and the depth H of the reflecting portion 5a are determined.
It was confirmed that both were preferably 0.3 mm or less.

In providing the reflecting portion 5a, the purpose of the reflecting portion 5a is to reflect light from the light source 4 toward the liquid crystal display element 2 to illuminate it. Is designed to widen the interval between the reflecting portions 5a and narrow the interval between the reflecting portions 5a at positions far from the light source 4 so that the display surface 2a is illuminated with uniform brightness.

Further, since the light control layer 5 is in close contact with the front surface 21b of the front glass substrate 21 on the back side, the light control layer 5 reflects and refracts at the boundary between the light control layer 5 and the front glass substrate 21. In order to prevent the occurrence of such a phenomenon, the refractive index of the resin member on which the light control
It is preferable that the refractive index is made equal to or very close to the refractive index of 1.

Here, a specific means for forming the light control layer 5 will be described. First, an ultraviolet curable resin having an appropriate viscosity is applied to the surface 21b of the front glass substrate 21 in an appropriate thickness. Then, after transferring the shape of the reflecting portion 5a to the film of the ultraviolet curable resin using a mold or the like and then irradiating and curing the ultraviolet ray, a plurality of reflecting portions 5a having a desired arrangement are obtained.
Can be formed.

The mold used at this time may be a transparent one made of glass or the like, and ultraviolet curing may be performed through the mold.
If ultraviolet curing is performed from the back side of 1 and the mold is removed after the curing of the ultraviolet curing resin, deformation after removing the mold due to the low viscosity of the ultraviolet curing resin before curing can be prevented, It can be expected that a more accurate light control layer 5 can be obtained.

With the above configuration, in the reflection type liquid crystal display device 1 of the present invention, light from the light source 4 is made incident on the front glass substrate 21 which is a high refractive member to the atmosphere, and the light is propagated. The light is reflected and illuminated by the reflecting portion 5a provided in a necessary portion, and no reflection occurs on the surface 21b of the front glass substrate 21, and uniformity is obtained by optimizing the arrangement of the reflecting portion 5a. Brightness can also be obtained.

Further, by optimizing the shape of the reflecting portion 5a, the illumination direction with respect to the liquid crystal display element 2 can be made closer to the surface 21b of the front glass substrate 21 in the vertical direction, so that a double image is generated. It can be prevented. Also,
Since the light from the light source 4 is made incident on the atmosphere into the front glass substrate 21 which is a high refractive member, light other than the light reflected by the reflecting portion 5a does not leak from the front glass substrate 21 and the illumination efficiency is improved.

In practicing the present invention, if the liquid crystal display element 2 is of a reflective type, it does not matter how to drive such as TFT driving or simple matrix driving.
The type of the liquid crystal display element 2 such as N-type, STN-type or guest-host type does not matter, and the present invention can be similarly applied to these various types.

FIG. 3 shows another embodiment of the present invention. In the previous embodiment, the reflecting portion 5a was formed as a line. However, the present invention is not limited to this. One of the reflection portions 5b may be formed in a dot shape as a substantially conical concave portion (so-called mortar shape). Also in this case, it is needless to say that the distribution is coarse at a position near the light source 4 and the distribution is dense at a position far from the light source 4 to enable illumination with uniform illuminance.

At this time, the maximum diameter D of the reflecting portion 5b,
The depth H and the like are assumed to conform to the dimensions described in the previous embodiment so as not to cause display disturbance or the like, and the formation of the reflecting portion 5b is as described in the previous embodiment. It can be realized by a similar method using an ultraviolet curable resin.

FIG. 4 shows still another embodiment of the present invention. Depending on the type of the liquid crystal display element 2 employed in the reflection type liquid crystal display device 1, the polarizing plate 6 is required on the surface 21b side. There is something. In this case, if the polarizing plate 6 is directly adhered to the front surface 21b with an adhesive, the adhesive fills the reflecting portion 5a of the light control layer 5, and the function as the reflecting portion 5a may be lost.

To cope with the above, according to the present invention, when the polarizing plate 6 is provided, an appropriate gap is provided between the light controlling layer 5 and the light controlling layer 5.
An air layer A having a refractive index of 1 is interposed between
The function of the reflection section 5a is maintained. Although not shown, when it is desired to integrate the light control layer 5 and the polarizing plate 6, an intervening layer made of a transparent adhesive having a lower refractive index than the light control layer 5 may be provided.

[0022]

As described above, according to the present invention, the illuminating device includes the light source provided on the end face of the glass substrate on the viewing direction side of the liquid crystal display element and the light source provided on the surface on the viewing direction side of the glass substrate. A reflection type liquid crystal display device comprising a light control layer formed of a transparent member having a refractive index substantially the same as that of the glass substrate and having a fine line-shaped or dot-shaped reflection portion provided on a surface on the viewing direction side; With this, the light from the light source is made incident on the front glass substrate, which is a high refraction member, into the atmosphere to propagate the light, and the light is reflected and illuminated by the reflector provided at the appropriate position, and the front glass There is no reflection of light from the light source on the surface of the substrate, and the arrangement of the reflection part is optimized, so that the display is illuminated with uniform brightness and the readability is improved, and the display quality is extremely improved. Has the effect of

Further, by optimizing the shape of the reflecting portion,
Since the illumination direction for the liquid crystal display element can also be perpendicular to the surface of the front glass substrate, the occurrence of double images can be prevented, and the display quality is extremely improved. On the other hand, since the light from the light source is made to enter the front glass substrate which is a high refractive member, the light other than the light reflected by the reflecting portion does not leak from the front glass substrate, and also has the effect of improving the illumination efficiency. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a reflection type liquid crystal display device according to the present invention.

FIG. 2 is a perspective view showing a main part of the same embodiment.

FIG. 3 is a perspective view showing another embodiment of the reflection type liquid crystal display device according to the present invention in a main part.

FIG. 4 is a sectional view showing still another embodiment of the reflection type liquid crystal display device according to the present invention.

FIG. 5 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reflective liquid crystal display device 2 ... Liquid crystal display element 2a ... Display surface 21 ... Glass substrate on the viewing direction side (front glass substrate) 21a ... End face 21b ... Surface on the viewing direction side (surface) 3 ... Illuminating device 4 ... Light source 5 ... Light control layer 5a, 5b ... Reflector 6 ... Polarizing plate

Claims (2)

[Claims] 1. A reflection type liquid crystal display device provided with a lighting device provided in a dark state, wherein the lighting device comprises: a light source provided on an end face of a glass substrate on a viewing direction side of a liquid crystal display element; A light control layer formed on the surface in the viewing direction by a transparent member having a refractive index substantially the same as that of the glass substrate, and provided with a fine line-shaped or dot-shaped reflecting portion on the surface in the viewing direction And a reflection type liquid crystal display device. 2. The polarizing plate provided on the viewing direction side of the liquid crystal display element is further positioned on the viewing direction side than the light control layer, and the light control layer has a lower refractive index than the light control layer. 2. The reflection type liquid crystal display device according to claim 1, wherein the reflection type liquid crystal display device is provided through a substance having a high ratio.