JPH0220825A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To constitute the color liquid crystal display device at low cost and to make a color display of high quality by using a transparent film for an optical compensating layer. CONSTITUTION:At least dichroic color filters 251 and 252, a liquid crystal layer 26 for display, and the optical compensating layer 27 which has the opposite optical axis twist direction from that of the liquid crystal layer 26 are stacked to compensate the coloring of the liquid crystal layer 26 by the optical compensating layer 27. Here, the optical compensating layer 27 consists of transparent films 281 and 282 which have refractive index anisotropy and this layer is provided for each color of the color filters 251 and 252, and the product of the refractive index anisotropy and film thickness is made difference by colors. The value and direction of the refractive index anisotropy of the transparent films 281 and 282 are set to prescribed values and elliptic polarized light guided out of the liquid crystal layer 26 is converted into nearly the same linear polarized light at the time of black display to obtain the same effect with a liquid crystal layer for compensation. Consequently, the optical compensating layer is constituted at low cost.

Description

[Detailed description of the invention] (Jll required) Display STN (Super Twisted N
cmatie) One liquid crystal layer and one optical compensation layer, S for display
Regarding a liquid crystal display device in which the coloring caused by birefringence of the TN liquid crystal layer is compensated for by an optical compensation layer, the optical compensation layer is intended to be constructed at a low cost. ! One layer is composed of a transparent film having anisotropy of refractive index, and this is provided for each color of the above color filter, and the product of the anisotropy of refractive index and the film thickness is calculated for each color. Tighten and configure.

[Industrial application field]

The present invention overlaps an S-N liquid crystal layer for display and an optical compensation layer,
The present invention relates to a liquid crystal display device in which coloration caused by birefringence of a display SrN liquid crystal layer is compensated for by an optical compensation layer.

In recent years, the development of black-and-white display liquid crystal panels using a 9-pure matrix system has been actively conducted, and in particular, there is a demand for the realization of a color liquid crystal display device that can be combined with a color filter and capable of displaying a large capacity. In this case, STN liquid crystal cells for display generally exhibit unnecessary coloring due to birefringence, and in order to eliminate this effect, an inexpensive and high-quality optical compensator is required to compensate for this unnecessary coloring.

[Conventional technology]

Conventionally, as a liquid crystal display device provided with the above-mentioned optical compensation plate, for example, Japanese Patent Laid-Open No. 57-96315 (Japanese Patent Application No. 55
The "two-layer liquid crystal display device" described in Japanese Patent Application No. 174406) and the "liquid crystal display device" described in Japanese Patent Application No. 1982-235345 have been proposed. A liquid crystal display device U using such an optical compensator is a so-called liquid crystal display device U in which a light beam transmitted through a polarizer and a display liquid crystal cell (generally having birefringence) becomes elliptically polarized light due to an optical rotational dispersion phenomenon and exhibits coloring. In order to reduce the coloring phenomenon, a compensating liquid crystal hill with a twist direction opposite to the liquid crystal molecule rice 1 direction of the display liquid crystal cell is newly installed, and the elliptically polarized light generated in the display liquid crystal cell is converted to the original linearly polarized light. put it back,
It is blocked by a polarizer to display black. In this case, the liquid crystal cells are made under almost the same conditions except that the twist direction of the liquid crystal molecules is reversed, and the liquid crystal cell compensates for the optical rotation dispersion phenomenon in the liquid crystal cell.

[Problem to be solved by the invention]

Although the liquid crystal cell used as the optical supplementary B layer has good characteristics, the glass substrate for the liquid crystal panel is generally expensive, and the yield of the liquid crystal panel is low, which makes it difficult to construct it at a low cost. was there.

An object of the present invention is to provide a color liquid crystal display device in which an optical compensation layer can be constructed at low cost.

[Means to solve the problem]

FIG. 1 shows a diagram of the principle of the present invention. In the same figure, 251°25
2, . . . are color filters of at least two colors, 26 is a display liquid crystal layer, and 27 is an optical compensation layer. In the present invention, the optical compensation layer 27 is formed of a transparent film 281 having a refractive index.
, 282 , ..., which is connected to the color filter 251
, 252, . . . are provided for each color, and the product of the anisotropy of the refractive index and the film thickness is made into a hole for each color.

[Effect]

By setting the magnitude and direction of the anisotropy of the refractive index of each transparent film 281, 282, ... to a predetermined value, the elliptically polarized light extracted from the liquid crystal layer 26 during black display is converted into linearly polarized light between the paths. can. In other words, the same effect as the compensation liquid crystal layer can be achieved.

In this case, since a transparent film is used, there is no need to use a glass substrate compared to the conventional example that uses a compensation liquid crystal panel, and the yield is good for the liquid crystal panel. Can be configured at low cost.

〔Example〕

FIG. 2 shows a configuration diagram of an embodiment of the present invention. In the same figure, 1
is the liquid crystal panel, glass plate 2, R (red).

Color filter 3n corresponding to G (green) and B (blue) respectively
, 3c, 3a s Matrix transparent electrode 4a.

4b, alignment film 5, for example ST with a 260° twist;
N-type liquid crystal 6 (cell thickness is, for example, 6 μm, refractive index anisotropy Δn is, for example, 0.15), sealing material 7, and glass plate 8
The liquid crystal panel 1 itself is the same as the conventional one. 9 is a backlight, and 10 is a polarizing plate.

11R, 11c, and 11s are transparent sheets made of, for example, stretched polymer films, each having an anisotropy of 1 refractive index Δn (Δn=parallel refractive index n/−vertical refractive index n
) and forms an optical compensation layer. in this case,
Seats 11R, 11G.

The stretching direction of the sheet 118 is set so that the light in the sheet rotates in the opposite direction to the rotation direction of the polarized light in the liquid crystal G. 12
is a polarizing plate. The present invention is characterized in that the optical compensation layer is not composed of liquid crystal but is composed of a member having anisotropy of refractive index.

FIG. 3 shows a diagram explaining the state of optical compensation.

In FIG. 3, white light 13 emitted from the backlight passes through a polarizing plate 10 to become linearly polarized light 14, and then passes through color filters 3R, 3G, and 3e to become three-color lights of R, G, and B. It is separated into 15R, 15c, and 15s.

Here, during black display, a relatively low voltage is applied to the liquid crystal 6 through transparent electrodes on both sides. As a result, the liquid crystal molecules of the liquid crystal 6 do not change, and since the liquid crystal 6 generally has birefringence, the liquid crystal 6
The light that has passed through is elliptically polarized light 16R, 16a for each color.
, 16s, sheets 11rz, 11c, 11
Pass B. In this case, sheets 11R, 11c, 1
If the magnitude of the refractive index anisotropy Δn, the direction of Δn, and the sheet thickness d of each of 1a are set to appropriate values for the elliptically polarized lights 16R, 16c, and 16o, the elliptically polarized lights 16R, 16
G, 168 is direct a-polarized light 17R, 17G, 17s between roads.
becomes. Since the linearly polarized lights 17R, 17a, and 17B do not pass through the polarizing plate 12, the elliptically polarized lights 16R, 16G, and 16
Unnecessary coloring due to B can be prevented, resulting in a black display.

On the other hand, for color display, a relatively high voltage is applied to the liquid crystal 6 through transparent electrodes on both sides. As a result, the liquid crystal molecules of the liquid crystal 6 are vertically polarized, and the light that has passed through the liquid crystal 6 is linearly polarized 18 times for each color.
R, 18G, 18a, sheets 11R, 11
c, passing through Ile. In this case, since the light passing through the liquid crystal 6 is linearly polarized light 18R918c, 18s, the sheets 11n, 11c, etc.

Contrary to the above case, the light passing through 118 becomes elliptically polarized light 19
rz, 19c, and 19a. Elliptically polarized light 19R119c
, 19s can pass through the polarizing plate 12, so R, G, and [3 are displayed, respectively.

Let us now consider the compensating action of the sheets 11R, 11c, and 11s. Seats 11R, 11c.

11B is the anisotropy of the refractive index Δn(Δ
n=parallel refractive index n/-perpendicular refractive index n) is Δn
R, Δn(=, Δn8, respectively. In this case, the anisotropy of the refractive index for each color ΔnR, ΔnG+
To make ΔnB different, for each color, only the size of Δ1 and only the direction of Δn (sheets 11R, 11c, 11B
(for example, 10°), or both the magnitude and direction of Δn may be made to be different from each other. For example, in one embodiment, when the sheet thicknesses d of the sheets 11R, 11G, and 11e are the same, the values of ΔnR, ΔnQ, and Δn8 are the elliptically polarized light 16R, 16c from the liquid crystal 6.

16B to linearly polarized light 17n, 17c, and 17e, and set the refractive index anisotropy Δn and sheet thickness d.
In other words, ΔnR-d of sea i~11R is 0.5
μs, ΔnQ-d of the sheet 11G is 0.6 μm, and ΔnB-d of the sheet 11c is 0.7 μm.

In this way, 1ii1 is applied to sheets 11n, 11c, and 11e.
When a stretched film having anisotropy Δn of the analysis rate is used, the stretched film substantially rotates the direction of light leakage in the same way as the compensation liquid crystal cell, so it is possible to perform optical compensation in the same way as the compensation liquid crystal cell. can.

However, since the value of Δn-d is different for each of the 68 colors, when displaying black, the elliptically polarized light 16R, 16c for each color
, 16o is correctly linearly polarized 17R217c, 17e
On the other hand, when displaying, the linearly polarized light for each color is 1
8R, 18c, 18s correctly elliptically polarized 19R, 1
9c, 19e, and high quality color display is possible.

In this case, to make Δn-d different for each color,
As mentioned above, only Δn is different for each color (Δn
Q, Δn (make it like zΔn6) and other Δn are the same,
The sheet thickness d may be different for each color, or both Δn and d may be different for each color.

In particular, the sheet can be configured in layers, and by setting Δn of each layer sheet to an appropriate value, the same effect as described above can be obtained.

Note that although the above embodiment is applied to three colors, R and G, the present invention is not limited to this, and the present invention can be applied to any combination of other colors or two or more colors.

〔Effect of the invention〕

As explained above, according to the present invention, since a transparent film is used for the optical compensation layer, it can be constructed at a lower cost than the conventional example using a compensation liquid crystal panel, and high-quality color display can be performed.

[Brief explanation of the drawing]

Figure 11. is a diagram of the principle of the present invention, Figure 2 is a configuration diagram of an embodiment of the present invention, Figure 3 is a diagram explaining the state of optical compensation, and Figure 4 is a diagram explaining the anisotropy of the refractive index of the sheet. It is. In the figure, 1 is a liquid crystal panel, 3R, 3c, 3e, 251, 252, ... are color filters, 4a, 4b are transparent electrodes, 6 is a liquid crystal, 10.12 is a polarizing plate, 11R, 11c, lle are transparent sheets, 14 is polarizing plate 1
15R, 15c, 15o are the linearly polarized lights that have passed through the color filter, 16R, 16G, 16e are the elliptically polarized lights that have passed through the liquid crystal, 17F<, 17c, 17e are the linearly polarized lights that have passed through the sheet, 18R, 18c and 18s are linearly polarized lights that have passed through the liquid crystal, 191-1.19G and 19s are elliptically polarized lights that have passed through the sheet, 26 is a display liquid crystal layer, 27 is an optical compensation layer, and 281, 282, . . . are transparent films. Patent Applicant: Fujitsu Co., Ltd. Kowomei Film Honbako Meisori Diagram - Figure 1 (Example of the Present Invention) I4. Figure 2

Claims (4)

[Claims] (1) At least two color filters (25_1, 2
5_2,...), a display liquid crystal layer (26), and an optical compensation layer (27) having an optical axis twist direction opposite to the optical axis twist direction of the display liquid crystal layer (26), and the display The optical compensation layer (27) removes the coloring generated in the liquid crystal layer (26).
In a color liquid crystal display device configured to compensate for ,...) are provided for each color, and the product of refractive index anisotropy and film thickness is made different for each color. (2) The transparent films (28_1, 28_2,...) are
Claim 1 characterized in that it is a stretched polymer film.
The color liquid crystal display device described. (3) The transparent films (28_1, 28_2,...) are
2. The color liquid crystal display device according to claim 1, wherein the direction of the anisotropy of the refractive index is different for each color. (4) The color liquid crystal display device according to claim 1, wherein the transparent films (28_1, 28, . . . ) have different degrees of anisotropy of the refractive index for each color.