JPS6298302A - Liquid crystal color display device - Google Patents

Abstract

PURPOSE:To obtain distinct color display by using mainly an anthraquinone pigment expressed by the formula for a red colorant of a color filter. CONSTITUTION:A first substrate and a second substrate, each having a transparent electrode, is arranged facing opposingly to each other in a liquid crystal element. Further, each picture element filter for R, B, and B each transmitting red, green and blue light selectively, is formed on the outside surface of the second substrate. An anthraquinone pigment expressed by the formula is used as a main colorant for the filter of the R picture element. Particularly preferred anthraquinone pigment is one having X1 and X2 both being NH2 in the formula. The anthraquinone pigments have spectroscopic characteristics suitable for colorant of red filter for a liquid crystal color display device. Moreover, the wavelength of the half width does not extend to the region of green light wavelength. Therefore, color mixing is inhibited effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal color display device using a liquid crystal element as an optical switching element, and more particularly to improvements in materials for forming color filters thereof.

Conventional technology Color display devices that apply liquid crystal elements have attracted attention in recent years because they can be made thinner. p, 2
11-240''.

Among liquid crystal color display devices, those using a liquid crystal element as a light shutter are expected.

In this system, pixel color filters of three primary colors, R2O and B, are arranged corresponding to the pixel electrodes of a liquid crystal element, and the light transmitted through the color filters is 1l IFN by illuminating with a backside light source.

Color filters used in such devices are required to have high transmittance and clear colors. Furthermore, if the transmission spectrum of a filter of another color overlaps, color mixing occurs and the color tone deteriorates. Therefore, in order to display a clear color image, it is necessary to prevent the half-value widths from overlapping with the transmission spectra of filters of other colors.

Conventionally, color filters have been formed by dyeing special resins such as protein and photoresist. However, this dye for dyeing has limitations, and sufficient color tone cannot be obtained, resulting in a lack of clarity in color display. Furthermore, the light resistance was also insufficient.

An object of the present invention is to realize clear color display in a liquid crystal color display device.

Viewing Structure The liquid crystal color display device of the present invention includes a liquid crystal element that controls transmission/blocking of electromagnetic waves according to image information, and a pixel-shaped color filter, and transmits light transmitted through the liquid crystal element to the color filter. In the liquid crystal color display device in which If is applied via the color filter, as the red coloring material of the color filter,
It is characterized by mainly using an anthraquinone pigment represented by the general formula (T).

(In the formula, X and x2 each represent H or NF2.) The present invention will be described in more detail below.

FIG. 1 is a sectional view schematically showing an embodiment of the present invention. a first substrate 15 with transparent electrodes 11, 13 respectively;
and a second substrate 17 are arranged to face each other, and this substrate 15
．． A TN type liquid crystal cell 21 is formed by sealing a TN type liquid crystal substance between the cells 17 and 17 . 19 indicates a sealing material. Liquid crystal cell 21 is 11! A 90°-TN type liquid crystal element 31 is sandwiched between the polarizing plate 23 on the viewing side and the polarizing plate 25 on the back side. This liquid crystal element can control the transmission and blocking of light from the light source 41 by applying a signal voltage between the electrodes 1, 1, 13, and functions as a light switching element. The light g41 is composed of a phosphor layer 43 and an ultraviolet lamp 45 as its energy source. 47 is a substrate holding a phosphor layer.

A color filter 3 on the pixel is provided on the outer surface of the second substrate 17.
3 is formed. The color filter 33 includes an R pixel filter 33a that selectively transmits red light, a G pixel filter 33b that selectively transmits green light, and a B pixel filter 33c that selectively transmits blue light. Each pixel filter 33a.

By observing the transmitted light of 33b and 33c using the liquid crystal element 31 as a light shutter, a full-color image is displayed.

As the main coloring material of the R pixel filter 33a, an anthraquinone pigment represented by the general formula (I) is used. Particularly preferable anthraquinone pigments have the general formula (1)
, X, , X2 are both NF2.

The anthraquinone pigment of the present invention has spectral characteristics suitable as a coloring material for red filters in liquid crystal color display devices, and also has a half-width wavelength range that does not extend to the green light wavelength range, making color mixing effective. It can be prevented. - For example, in general formula (1), both X□ and X2 are N
The spectral transmission spectrum of a filter in which an anthraquinone pigment (F2) was dispersed in a resin binder and applied to a thickness of about 3 μm is shown as TR in FIG.

The color filter 33 is obtained by dispersing pigment in a resin binder and forming a pattern using a printing method such as screen printing. The pigment is preferably fine particles with an average particle size of 2 μm or less. The appropriate thickness of the color filter is about 0.5 to 5 μm, preferably 1 to 3 μm.
It is m. Furthermore, each color filter can also cut unnecessary wavelengths or control color tone using a plurality of color materials.

The color materials used for the G pixel filter 33b and the B pixel filter 33c are appropriately selected so that the half widths of their transmission spectra do not overlap, and examples thereof include phthalocyanine blue and phthalocyanine green. As a preferable pigment for G pixel filter, the following general formula (
II), phthalocyanine pigments represented by (I[I) or (IV).

(In the formula, Yl, Y2.Y,,Y, represents C1 or Br, and ni+nz+ni+n represents 1 to 4.) (Hereinafter, the margins are blank) (In the formula, z,, z2.z3.z, represents CI Or Br
, m 1r m Z l m 3 and lT14 indicate 1-4. ) (where Y, , YG, Y, , Y is H
or COONa. ) In the general formula (TI), X is 01, and the spectral transmission spectrum of a phthalocyanine pigment containing 15 to 16 in total is shown in FIG.

In FIG. 1, the phosphor layer 43 can be formed by dispersing and coating phosphor particles that emit light in R, G, and B in a binder. Further, the phosphor can be formed in the shape of R, G, and B pixels corresponding to each of the R2O and B pixel filter sections.

The light emitted from the phosphor is additively mixed by a color filter, and a brighter and better color image can be obtained. Here, the relationship between the emission spectrum of the phosphor and the transmission spectrum of the color filter is important, but since the anthraquinone red pigment of the present invention has a transmission spectrum suitable as a coloring material for the R filter, it can be used for good color display. It can be realized. FIG. 2 shows an example of the phosphor emission spectrum as ER.

The position of the color filter is not limited to that shown in FIG. 1; for example, it can be formed on the transparent electrode, on the first substrate surface, or on the polarizing plate 25 or on another separate substrate. It can also be provided in

The gist of the present invention is to use an anthraquinone red pigment in a color filter of a liquid crystal color display device, and other components may be appropriately selected.

For example, electroluminescence (E
L) A light emitter, a fluorescent lamp, a white lamp, etc. can be used, and as for the liquid crystal element, any liquid crystal element can be used as long as it functions as a light shutter, such as a guest-host type.

According to the present invention, a clear color image can be obtained by using an anthraquinone red pigment represented by the general formula (1) as a red coloring material of a color filter in a liquid crystal color display device.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal color display device of the present invention. FIG. 2 is a graph showing an example of the spectral transmission spectrum of the anthraquinone red pigment used in the present invention and the emission spectrum of the phosphor. FIG. 3 is a graph showing an example of the spectral transmission spectrum of a green pigment. 11. 13...Transparent electrode 15...First substrate 17...Second substrate 21...Liquid crystal cell 31
...Liquid crystal element 33...Color filter 4
I... Light source 43... Phosphor layer 4
5...UV lamp

Claims (1)

[Claims] 1. It has a liquid crystal element that controls transmission/blocking of electromagnetic waves according to image information and a pixel-shaped color filter, and the light transmitted through the liquid crystal element is observed through the color filter. In the liquid crystal color display device, the red coloring material of the color filter is mainly represented by the general formula (I) ▲mathematical formula, chemical formula, table, etc.▼(I) (where X_1 and X_2 are hydrogen or amino, respectively. A liquid crystal color display device characterized by using an anthraquinone pigment represented by the following.