JPS6252533A - Liquid crystal color display panel - Google Patents

Abstract

PURPOSE:To realize a color display with extremely high color purity by constituting a back light source by using a thin EL panel which has a sharp spectrum in any of wavelength areas of blue, green, and red. CONSTITUTION:The thin film EL panel which has a transparent electrode film 15, an insulating film 15A, a light emission layer thin film 16, an insulating film 15B, and an Al metallic electrode film 17 manufactured successively on a glass substrate 13 is arranged behind a polarizing plate 7B. When an electric field is applied to selected parts of electrodes 10A and 10B of a liquid crystal optical shutter to turn off the liquid crystal optical shutter, the light of the thin film EL panel is guided out at selected picture elements through a color filter 11, liquid crystal 12, and a polarizing plate 7A, so only the bright line spectrum of the thin film EL panel is led out, so that blue, green, or red is recognized. When the liquid crystal optical shutter is off, no light is transmitted through the liquid crystal, so the emitted light of the thin film EL is not guided out and the light emission light is not observed from outside.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid crystal color display panel,
More specifically, thin film electroluminescence (EL) is used in the rear light source, which is a component of the liquid crystal color display panel.
The present invention relates to a liquid crystal color display panel using a panel.

[Conventional technology]

Liquid crystal display panels have reached the practical stage, and portable liquid crystal televisions,
It is essential to colorize the 0 display, which is widely applied to computer displays and is currently in the colorization stage, due to the increase in the amount of information due to color identification.
Most image display devices using CRT display color.

Color display on a liquid crystal display panel can basically be achieved by using a liquid crystal optical shutter that uses twisted nematic mode, etc., and a multicolor filter placed on the back of this optical shutter. In order to improve display quality, an illumination light source that illuminates the multicolor filter from behind is an essential component.

Conventional multicolor filters for LCD color display panels include:
Three types of organic materials that transmit light in the blue, green, or red light range are provided on a glass substrate or a liquid crystal electrode film by vapor deposition or printing. Typical transmission spectral characteristics of the polychromatic filter are shown in Figure 4.
In the figure, curve 1 is a spectral curve of a filter that transmits blue light, curve 2 transmits green light, and curve 3 transmits red light.

Furthermore, a mercury fluorescent lamp emitting white light is used as an illumination light source for a conventional liquid crystal color display panel, and its emission spectrum is as shown in FIG. Therefore, in a conventional color display panel that combines the multicolor filter shown in FIG. 4 and the light source shown in FIG. 5, as shown in FIG. The light of
As red light, the light in region 6 will be perceived by the observer. As is clear from Figure 6, all of these lights have a broadband wavelength distribution, and therefore have poor color purity compared to CRT, and are insufficient as three primary colors, and can be obtained by mixing them. Intermediate colors also had the disadvantage of poor hue.

Furthermore, if such a fluorescent lamp is used as a light source for backlighting, the volume becomes large and the advantage of thinness of the liquid crystal is lost.Furthermore, since fluorescent lamps are linear light sources, it becomes difficult to make the panel large in area. Another drawback was that it became difficult to provide uniform illumination, resulting in uneven illumination.

Note that attempts have also been made to use a conventional EL panel as a backlighting light source as a surface light source for uniformly illuminating the entire surface of a thin, large-area liquid crystal display panel. However, the EL illumination light sources that have been proposed so far emit monochromatic light, so they can only be used for monochrome display panels.
It has the disadvantage that it cannot be used as a white light source for a color display panel composed of a multicolor filter and a liquid crystal light shutter.

[Problem that the invention seeks to solve]

Therefore, the purpose of the present invention is to solve the problem of the conventional color purity being poor.
An object of the present invention is to provide a liquid crystal color display panel suitably configured to solve the problem of a large volume of a light source part and uneven illumination.

[Means for solving problems]

To achieve such an object, the present invention provides a liquid crystal color display panel having a liquid crystal light shutter, a multicolor filter, and a light source for illuminating at least one of the liquid crystal shutter and the multicolor filter, wherein the light source has a blue color. , a thin film electroluminescent panel including a light emitting film having both green and red emission spectra.

[For production]

The present invention utilizes the characteristic that the emission spectrum of a thin film EL element, particularly an element doped with a rare earth metal compound as a luminescence center, is a sharp emission line spectrum, and utilizes the characteristic that the emission spectrum of a thin film EL element, especially an element doped with a rare earth metal compound as a luminescence center, is a sharp emission line spectrum. In contrast to the conventional technology, by constructing the back light source using a thin film EL panel that has a sharp spectrum in the region,
This has the effect of realizing color display with extremely high color purity. In addition, in the present invention, since a thin film EL panel is used as a backlight source, it is possible to obtain a thin and uniform surface emission distribution having emission spectrum components ranging from blue to red.

〔Example〕

The present invention will be described in detail below using Examples.

FIG. 1 shows an embodiment of the present invention, in which 7A and 7B are polarizing plates, 8A and 8B are glass plates arranged on the rear and front surfaces of the polarizing plates 7A and 7B, respectively, which sandwich the liquid crystal; A spacer 9 is placed between the glass plates 8A and 8B and determines the gap in which the liquid crystal is filled. IOA and 10B are transparent electrodes for applying an electric field to the liquid crystal, and the electrode 10A is fixed to the glass plate 8A, and the electrode 10B is fixed to the glass plate 10B. Electrode 10A
is in the form of a flat plate, and the electrode 10B has a shape corresponding to a color filter. 11 is a color filter layer arranged on the electrode 10B, 12 is a liquid crystal filled in the space formed by the glass plates 8A, 8B and the spacer 9.0 or more constitute a liquid crystal light shutter and a multicolor filter. .

Furthermore, a glass substrate 13 is arranged behind the polarizing plate 7B,
On this glass substrate 13, an In2O3:Sn transparent electrode film 14, a Taa05 insulating film 15A, a TmF3.
ZnS light emitting layer thin film 16 doped with TbF3 and SmF3 in an amount of 1 to 3% by weight, respectively, Taz05 insulating film 15B,
A thin film EL panel prepared by sequentially forming pattern A metal electrode films 17 by sputtering is arranged.

In order to perform color display using this display panel, an alternating current is first applied between the opposing electrodes 14 and 17 of the thin film EL panel. Thereby the light emitting layer in the thin film EL panel becomes thin
16 emits light uniformly over the entire surface. Its emission spectrum consists of the emission centers T m , T b , S
Specifically, blue emission with a wavelength of 480 nm is caused by the Tm emission center, blue emission with a wavelength of 488 nm and green emission with a wavelength of 542 nm is caused by the Tb emission center, and emission with a wavelength of 565 nm is caused by the Sm emission center. A total of six bright line spectra of green light emission and red light emission with wavelengths of 602 nm and 648 nm are emitted simultaneously.

When an electric field is applied to a selected portion of the electrode 10A and IOB of the liquid crystal light shutter and the liquid crystal light shutter is turned on from an off state, the light from the thin 11EL panel passes through the color filter 11. Since the light goes out through the liquid crystal 12 and the polarizing plate 7A, only the bright line spectrum in the transmitted light region of the filter among the light emission bright line spectra of the thin film EL panel is extracted to the outside and is recognized as blue, green, or red. Note that when the liquid crystal light shutter is in an off state, the liquid crystal does not transmit light, so the light emitted from the thin film EL does not go out to the outside, and the color of the emitted light is not observed from the outside.

FIG. 2 shows the unprocessed i-optical layer thin film 16 made of TmF on ZnS.
3, TbF3, and SmF3 are simultaneously added as luminescent centers. Areas 18, 19, and 20 in Figure 1 represent blue filter (characteristic 1 in Figure 4) and green filter, respectively. It shows the portion taken out through the filter (characteristic ? in Figure 4) and the red filter (characteristic 3 in Figure 4).

Figure 3 shows the liquid crystal color display panel of this example (blue CB),
It is a diagram showing the chromaticity of the three primary colors of green (G) and red (R) in comparison with the three primary colors of a conventional panel, in which 21 shows the characteristics of the panel of this example, and 22 shows the characteristics of the conventional panel. There is something that shows this.

As can be seen from FIGS. 3 and 4, in the present invention, blue,
Since a thin-film EL panel that emits green and red components simultaneously is used as a backlighting light source, the emission spectrum has fewer bright lines and is separated, each of which is sharp. Therefore, a panel that uses conventional fluorescent lamps as a light source It can be seen that the color purity of the displayed color is higher than that of the previous model, and that a wide range of intermediate colors can be obtained by the color mixing method.

Furthermore, thin-film EL panels have the advantage of being thin and uniformly emitting light, so by using a thin-film EL panel as an illumination light source, the entire liquid crystal color display panel can be made thinner, and uniform display over a large area can be achieved. realizable.

In this example, a sputtering method was used as a method for manufacturing a thin film EL panel, but thin It! IEL panels can be produced.

In configuring the light emitting layer thin film 16, in this embodiment, Z
TmF3, TbF3 and SmF3 were added to nS at the same time, but the ZnS thin film with only TmF3 added and T
A structure in which a ZnS@ film to which only bF3 is added and a ZnS thin film to which only SmF3 is added may be stacked.

Alternatively, since the ZnS thin film doped with TbF3 has an emission spectrum in both the blue and green regions, as described in the explanation of the example, TbF3 is used as the emission center.
It is also possible to use only two types of ZnS, 3 and SmF3, and use as a light-emitting layer a ZnS thin film to which these are added simultaneously or a stack of ZnS thin films to which these are added individually.

In addition, as light-emitting layer materials for thin film EL, materials that can emit blue light include CeF3 or CeCn3-doped Sr.
S film, CeCfL s-added ca as a green-emitting film
There are ZnS films doped with S III or TbP, and CaS films doped with 3g of EuC as those that emit red light. By selecting an appropriate combination of these, the light-emitting layer of the present invention, that is, in any of the blue, green, and red regions, can be formed. A thin film EL light emitting layer 16 having a sharp emission spectrum may be formed.

By the way, the insulating film 1 in the thin film EL panel structure shown in the first figure
Since 5A and 15B are intended for electrical protection of the panel, insulating film materials include Ta, Os (7) used in the above example, and Y: L03, 5j4).
03, S+sNa 1Au203, BaTiO3
, PbTiO3, 5rTi03, etc. may be used, and if the light emitting layer thin film 16 has a sufficient electrical withstand voltage, the structure may be such that only one layer of such an insulating film is provided, or even if no insulating film is provided at all. good.

It goes without saying that in the liquid crystal color display panel of the present invention, there are no limitations on the composition or material of the liquid crystal light shutter and color filter, except that the backlighting light source is constructed as described above. For example, the order of arrangement of the color filter and the liquid crystal light shutter disposed in front of the illumination light source may be reversed, instead of being arranged in this order as shown in the first figure; Instead of configuring the liquid crystal light shutter and color filter as one unit as shown in Figure 1, they may be configured separately and placed in combination. In contrast, light-emitting films having blue, green, and red emission spectra are arranged individually or in an integrated manner, and regions of these colors are arranged in dot shapes or stripes such as circles, squares, and triangles. It can be in the form of

[Effects of the Invention] As explained above, according to the present invention, it is possible to display a wide range of neutral colors with high purity in one color, and also to configure a thin display panel without uneven luminescence, which makes it possible to use information input/output equipment. It has the advantage of being able to provide high-performance 1000-sided brass i-rabbit panels that are ideal for home and home equipment.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention, FIG. 2 is an emission spectrum diagram of an illumination light source EL panel in an embodiment of the present invention, and FIG. 3 is a liquid crystal color display panel of the conventional and the present invention. Figure 4 is a transmission spectral characteristic diagram of a multicolor filter, Figure 5 is an emission spectrum diagram of a mercury fluorescent lamp illumination light source, and Figure 6 is a combination of a multicolor filter and a mercury fluorescent lamp. FIG. 3 is a diagram showing the spectral range of light extracted when 7A, 7B...Polarizing plate, 8A, 8B...Glass plate for liquid crystal light shutter, 9...
・Spacer, 10A, IOB...Transparent electrode, 11...Multicolor filter film, 12...Liquid crystal, 13...: Glass substrate for thin film EL panel, 14...Transparent electrode, 15A, 15B... - Insulating film, 16... Blue, green, red simultaneous light emitting thin film light emitting layer, 17...
Metal electrode, 21... Chromaticity region of the panel of the present invention, 22... Chromaticity region of the conventional panel. Patent Applicant Nippon Telegraph and Telephone Corporation Agent Patent Attorney Yoshi Tani - Cross-sectional view of the V-direction Hii line in Mokuden Ming Figure 1 Perfect strength (Ichi Higashigoi) tsu; Figure 4 Figure 5 The scale of the mercury firefly in the lamplight, Figure 5.

Claims (1)

[Claims] In a liquid crystal color display panel having a liquid crystal light shutter, a multicolor filter, and a light source illuminating at least one of the liquid crystal light shutter and the multicolor filter, the light source may emit any one of blue, green, and red light emission spectra. 1. A liquid crystal color display panel comprising a thin film electroluminescent panel including a light emitting film having the following properties.