JPS6117102A - Transmission type color liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease the reflection of light before and behind a color temp. correcting filter layer and to obtain a distinct display by printing directly the color temp. correcting filter layer on a colored layer to be printed on a polarizing plate. CONSTITUTION:The colored layer 15 is provided by printing on the rear surface of the polarizing plate 13 and the color temp. correcting filter layer 20 is directly printed on the rear of the layer 15. The layer 20 has the effect of increasing the color temp. of an illuminating light source 14 of, for example, about 2,500 deg.K to >=3,000 deg.K, more preferably 3,500-5,000 deg.K. The layer 20 is obtd. by adding a coloring agent into a transparent resin such as vinyl chloride resin or vinyl chloride/acryl copolymer resin. The light of light source 14 transmits well the layer 20 and the layer 15 if the layer 15 and the layer 20 are printed to 5-10mum thickness. The distinct observation of the display of a liquid crystal cell 11 is thus made possible.

Description

TECHNICAL FIELD The present invention relates to a transmissive color liquid crystal display device, and particularly to a color liquid crystal display device that displays at a color temperature different from that of an illumination light source.

"Prior Art and its Problems" Among color liquid crystal display devices, the so-called transmissive type is a type that has an illumination light source on the back side of a liquid crystal unit for visual recognition of the display. Conventionally, incandescent light bulbs such as tungsten lamps have been used as this illumination light source, but the color temperature of tungsten lamps is as low as about 2500°, so this is used as a polarizer for liquid crystal cells and liquid crystal cells. There is a problem in that when the colored layer attached to the screen is transmitted through, the displayed color becomes reddish. In particular, depending on the colored layer, yellowish, front thread, edge thread,
Alternatively, if an attempt is made to obtain a blue-edged display, the reddish effect of the illumination light source is likely to appear, and this problem is significant. For this reason, in conventional transmissive color liquid crystal display devices, in order to correct the color temperature of the illumination light source, a color correction filter lO is generally provided as shown in FIG. This transmission type color liquid crystal display device CD is a TN type negative display element, and polarizing plates 12 and 13 are bonded to the front and back sides of the liquid crystal cell 11, respectively, and an arbitrary Colored layer 15 is printed, colored layer 1
5, the color temperature correction filter 10 made of a separately placed film is closely attached. Color temperature correction filter 1
0 is usually a blue film in order to raise the color temperature of the illumination light source 14.

However, in this conventional device, even if the color temperature correction filter lO is mechanically brought into close contact with the colored layer 15, microscopically,
Since a slight air layer is created between the two, a light loss occurs due to light reflection at the boundary between this air layer and the color temperature correction filter 10 and the colored layer 15. As a result, the amount of transmitted light decreases and the display becomes difficult. There is a problem with getting dark. Furthermore, since the color temperature correction filter 10 must be prepared as a separate film from the liquid crystal cell 11 in which the polarizing plates 12 and 13 are integrated, it is disadvantageous in terms of parts management and number of parts. Due to long-term use, this film made of a separate member may be deformed and may peel off from the polarizing plate 13.

"Summary of the Invention" The present invention has been made with the aim of solving the problems of the conventional device described above. Based on the analysis that this problem occurs because the filter is supplied as a film, the idea was to print and form the color temperature correction filter layer on the colored layer of the polarizing plate.

That is, the transmissive color liquid crystal display device of the present invention includes a liquid crystal cell having a polarizing plate attached to at least the illumination light source side, a colored layer attached to the polarizing plate, and a color temperature correction filter layer directly laminated on the colored layer. It is characterized by being printed using According to this configuration, since no air layer is formed between the colored layer and the color temperature correction filter layer, there is no decrease in transmitted light and the display becomes brighter. Since the film is not supplied as a single film, it is possible to eliminate the trouble of parts management that was conventionally required for film. Furthermore, there is no need to consider the high-temperature reliability of separately placed members, and reliability can also be improved.

"Detailed Description of the Invention" The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a conceptual diagram of a transmissive color liquid crystal display device of the present invention, in which a liquid crystal cell 11, a polarizing plate 12, 13, and a colored layer 1 are shown.
5 is the same element as the conventional device. The colored layer 15 is attached to the back surface of the polarizing plate 13 by printing.

A color temperature correction filter layer 20 is printed directly on the back surface of this colored layer 15. This color temperature correction filter layer 20 has the function of increasing the color temperature of the illumination light source 14, which is approximately 2500'K as described above, to 3000'K or more, preferably 3500'K to 5000'K.

Specifically, this color temperature correction filter layer 20 is obtained by adding a coloring agent to a transparent resin such as a vinyl chloride resin or a vinyl chloride/acrylic copolymer resin. For the purpose of increasing the color temperature, it is preferable to use a coloring agent for the front yarn. As the coloring agent, various dyes can be used, such as a mixture of Green 75 or 77 (manufactured by Jujo Kako) and Marine Blue 86 or 87. The addition ratio of the colorant to the transparent resin is preferably 20 to 50% by weight. If it is less than 20%, sufficient color temperature correction effect cannot be obtained, and if it exceeds 5oz,
The tone of the displayed color changes, making it impossible to obtain the desired color.

Particularly preferably, the weight is 25 to 40% by weight.

The dye of the desired color and the transparent resin are mixed using an appropriate solvent to form an ink (paste). When this ink is printed on the colored layer 15, the color temperature correction filter layer 20 is formed on the colored layer 15 without microscopic gaps.

If the printing thickness of both the colored layer 15 and the color temperature correction filter layer 20 is 5 to 10 μm, the light from the illumination light source 14 will be good.
It is possible to clearly observe the display of the liquid crystal cell 11 through the light.

"Embodiments of the Invention" 30 g of a mixture of Green 75 and Marine Blue 8B (weight ratio 50:1) as a colorant, 60 g of medium as a vinyl chloride/acrylic copolymer resin, and calpitol and cyclohexanone as solvents. A color temperature correction filter layer printing ink was prepared by mixing these together using 30 g of Trubet, which is a mixed solvent. As shown in Figure 2, the spectral characteristics (transmitted light spectrum) of this ink are approximately 52
It had a transmitted light peak at 0 nm. Using this ink, a color temperature correction filter layer 20 having an average thickness of 7 pm was printed on the pale yellow colored layer 15 to manufacture the present transmission type color liquid crystal display device CD. Color temperature 2500 as illumination light source 14
When the liquid crystal cell 11 was driven using a K tungsten lamp and the display was observed, no reddish due to the illumination light source 14 was observed in the displayed color, and the colored layer 15 and the color temperature correction filter layer 20 A clear green color with overlapping colors was clearly observed.

It was found that there was substantially no light loss due to reflection of transmitted light by the color temperature correction filter layer 20.

It should be noted that the present invention has the same effect even when applied to a transmission type (ζ guest host) negative type display element in which a polarizing plate is provided only on the illumination light source side of a liquid crystal cell.

"Effects of the Invention" As described above, the transmissive color liquid crystal display device of the present invention has a color temperature correction filter layer printed directly on the colored layer attached to the polarizing plate. Compared to conventional devices that are supplied as a film made of a separate member from the cell, it is possible to reduce the reflection of light before and after the color temperature correction filter layer, and therefore it is possible to obtain a clear display. Furthermore, since there is no need to prepare a color temperature correction filter as a separate member, it is advantageous in terms of parts management, and there is also the advantage that there is no risk of peeling off from the colored layer.

[Brief explanation of drawings]

FIG. 1 is a conceptual cross-sectional view showing a configuration example of a transmissive color liquid crystal display device according to the present invention, FIG. 2 is a graph showing an example of spectral characteristics of a color temperature correction filter layer according to the present invention, and FIG. 1 is a conceptual cross-sectional view showing an example of a display device. 11...Liquid crystal cell, 12.13...Polarizing plate, 14.
...Illumination light source, 15... Colored layer, 2o... Color temperature correction filter layer. Figure 1

Claims (5)

[Claims] (1) In a transmissive color liquid crystal display device in which a liquid crystal cell has a polarizing plate attached to at least the side of the illumination light source, a colored layer is attached to the polarizing plate, and a color temperature correction filter is provided between the colored layer and the illumination light source. . A transmissive color liquid crystal display device, characterized in that the colored layer and the color temperature correction filter layer are laminated and printed on the back surface of the polarizing plate. (2) A transmissive color liquid crystal display device according to claim 1, wherein the color temperature correction filter layer is formed by mixing a coloring agent into a transparent resin. (3) In claim 2, the transparent resin is made of a vinyl chloride resin or a vinyl chloride/acrylic copolymer resin, and the colorant is a blue dye. . (4) A transmission type color liquid crystal display device according to claim 2 or 3, wherein the coloring agent is added in an amount of 20 to 50% by weight in the transparent resin. (5) A transmissive color liquid crystal display device according to any one of claims 1 to 4, wherein the colored layer and the color temperature correction filter layer each have a thickness of 5 to 10 μm.