JPS6278527A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To see a display at wide angle by providing a polarizing plate and a color filter having light dispersing property in a liquid crystal display element. CONSTITUTION:A color filter 3' having light dispersing characteristic can easily be formed by mixing a material of different refractive index, for instance, a transparent material obtained by cutting glass fiber making it granules sufficiently smaller than the film thickness of a color filter 3. When incident light L1 is projected from backside of a liquid crystal display device, the light passes through a polarizing plate 1b on the backside and enters a liquid crystal display element 5' and polarizing controlled by liquid crystal 4. Further, the light is dispersed assuming various colors and transmitted through a front side polarizing plate 1a and diffused in wide extent toward front side becoming tranmitted light L2'. Thus, the visual angle can be widened.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a liquid crystal display device, and particularly to a color liquid crystal display device comprising a TN (twisted nematic) type liquid crystal display element and a color filter. .

[Background of the invention]

FIG. 3 is a sectional view of a main part of this type of color liquid crystal display device. In the same figure, ia, 1b are polarizing plates, 2m, 2
b is a translucent glass substrate, 3 is a front side translucent glass substrate 2
Red (R) placed inside a.

Color filters having green (G) and blue (B) colors, 4
is a TN type liquid crystal disposed between glass substrates 2m and 2b, and the aforementioned glass substrates 2m and 2b, color filter 3 and liquid crystal 4 constitute a color liquid crystal display element 5. Note that Ll is incident light and L2 is transmitted light.

However, since the color liquid crystal display device configured in this way performs display using the polarization characteristics of the liquid crystal 4, when the viewing angle changes, the polarization characteristics of the liquid crystal 4 apparently change, and the color tone changes. There was a problem with this. This phenomenon is particularly noticeable in TV images that display halftones, and has become a serious problem when displaying TV images using liquid crystal 4 (Nikkei Electronics 1984).
9°10, PP211-240. ). In order to further expand the viewing angle, there has been an attempt to make the light source of the incident light L1 incident from the back side of the liquid crystal display element 5 scattering, but this brings out the problems described above.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can display a color image at a wide viewing angle, with little change in color tone of the image even at a wide viewing angle.

[Summary of the invention]

In order to achieve such an object, a liquid crystal display device according to the present invention has a polarizing plate and a color filter having light scattering properties disposed inside a liquid crystal display element. That is, in order to widen the viewing angle of the liquid crystal display element, K only needs to scatter the light that has passed through the liquid crystal display element. However, the color of the substance that causes scattering is generally white, and when a scattering substance is added to the front side of a liquid crystal display element, it causes reflection of external light and increases the contrast of the transmitted light that passes through the liquid crystal display element. significantly reduced. Hence red.

If a color liquid crystal display device uses green and blue color filters and the color filters have a scattering structure, each color filter will be able to adjust the contrast of the light that passes through the liquid crystal display device depending on the wavelength of visible light. The viewing angle can be expanded with almost no reduction.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a sectional view of a main part of an embodiment of a liquid crystal display device according to the present invention. The same parts as those in the previous figures are given the same reference numerals. In the figure, the inside of the front glass substrate 2a has a polarizing plate 1a and light diffusion characteristics, and red (R) and green (
A liquid crystal display device 5' is constituted by color filters 3' having color filters 3' for each of the colors G) and blue (B). The color filter 3' having this light-scattering characteristic can be easily produced by mixing a light-transmitting substance with a different refractive index, such as cut glass fiber, in the form of particles that are sufficiently smaller than the film thickness of the color filter 3 described above. In such a configuration, the incident light from the back side of the liquid crystal display device,
When the light is incident, it passes through the polarizing plate 1b on the back side and enters the liquid crystal display element 5', and the polarization is controlled by the liquid crystal 4. Furthermore, the light is colored in each color by the scattering color filter 3'. The light is scattered and transmitted through the front polarizing plate 1&, transmitted toward the front side, and is diffused over a wide range as '.
The viewing angle can be expanded to 60 to 70 degrees compared to the conventional viewing angle of about 45 degrees. In addition, since the light-scattering color filter 3' contains granular light-transmitting substances inside, the optical path length when incident light is transmitted becomes longer.
Red (R) in Figure 2 (-), (b), and (C).

In order to show the spectral transmittance characteristics of the green (G) and blue (B) color filters, the characteristics in the absorption wavelength range of each color are changed from the conventional several lines shown by the solid lines In, Ia, and Is to the dotted lines nst,
I1. ．． As shown by n, the absorption decreases to several tens of magnitude. For example, if the optical path length is approximately doubled, the dye concentration can be reduced to approximately 4 times. Therefore, changes in color tone can be reduced.

〔Effect of the invention〕

As explained above, the present invention can enlarge the viewing angle by several tens of degrees by disposing a polarizing plate and a color filter having light scattering properties in the liquid crystal display element.
An extremely excellent effect can be obtained in that the display anvil can be viewed from a wide angle, which was previously not possible only from a specific direction.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal display device according to the present invention, and FIG. 2 (,), (b), and (C) are R, G
FIG. 3 is a cross-sectional view of a conventional liquid crystal display device. 1@, 11) * e 11 * Polarizing plate, 2@, 'lb
* * e @Transparent glass substrate, 3'...light diffusing color filter, 4...liquid crystal, 5'...color liquid crystal display element, Ll...incident light, L2 ・
···Transmitted light. , -ゝ、Representative Patent Attorney Katsutoshi Ogawa Figure 1 L'2 Figure 2 (Q) (b) (C) Density-+(nm)
;L 1((""'JFig. 3

Claims (1)

[Claims] In a liquid crystal display device comprising a liquid crystal display element, a pair of polarizing plates, and a color filter, a combination of a polarizing plate and a color filter having light scattering properties is arranged inside the liquid crystal display element. A liquid crystal display device characterized by: