JPS61112129A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To simplify a process and to prevent yield from reduction by dividing respective color filters by light absorbing stripes constituted by the overlap of red and blue color filters. CONSTITUTION:A red (R) color filter is selected for a picture element part corresponding to ordinary R and a part corresponding to black stripes at first, and then a blue (B) color filter is formed on a picture element part corresponding to ordinary B and a part corresponding to the black stripes. Finally, a part corresponding to green (G) color stripes of a picture element corresponding to G is constituted by the overlap of R and B color filters. The film thickness of the R, B and G color filters is controlled so that the thickness values dR, dG, dB of liquid crystal layers corresponding to respective R, G and B color filters are optically optimized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to color filters and liquid crystals, especially twisted
The present invention relates to a color liquid crystal display device configured by combining a nematic liquid crystal (hereinafter abbreviated as TN liquid crystal).

(Conventional Structures and Their Problems) Liquid crystal display devices are thin, can be driven at low voltages, and have low power consumption, so the market needs for flat displays have been rapidly increasing recently.

Conventionally, monochrome display devices have been mainstream, but color liquid crystal display devices capable of color display using red, green, and blue (hereinafter abbreviated as R, G, and B) color filters are about to be commercialized. In addition, from a driving perspective, even if the number of scanning lines is increased to increase the resolution of the display, it is possible to display images with excellent contrast and visual dependence, so TP
An active matrix method that incorporates switching elements such as T (thin film transistors) and drives liquid crystals is also being used.

A conventional color liquid crystal display device in which liquid crystal is driven by TPT will be explained based on FIG. This figure is a sectional view of the panel part of a color liquid crystal display device, in which 1 is a TN liquid crystal, 2a,
2b is an alignment film for controlling the initial alignment of the TN liquid crystal 1 when no voltage is applied, and 3a and 3b are transparent electrodes. The transparent electrode 3b corresponds to a picture element electrode, and is electrically connected to a TPT drain electrode 4b, which will be described later. 4a is a source, 4b is a train electrode, 5 is a semiconductor, 6 is a gate,
7 is an insulating film, which constitutes the TPT. The insulating film 7 serves as a gate insulating layer of the TPT and a source and gate insulating layer.

8a, 8b, and 8c are R, G, and B color filters, 9a, 9b are transparent substrates, and 10 is a black stripe that partitions the color filters 8ay8bv8c.

The operation of the conventional color liquid crystal display device configured as described above will be explained.

First, when a scanning signal is applied to the gate 6, the TPT is turned on, conduction occurs between the source 4a and the drain electrode 4b, and the liquid crystal layer 1 is charged with a video signal applied from the source 4a.

Even if the scanning signal disappears, the TPT is turned off, so voltage continues to be applied to the liquid crystal layer between the transparent electrodes 3a and 3b. Since the amount of light transmitted through the liquid crystal layer changes depending on the voltage applied to the liquid crystal layer, it is possible to control the amount of light transmitted by the video signal voltage. The electric charge given to the liquid crystal layer 1 is applied to the gate when the next scanning signal is applied, and the TPT becomes O.
Until the next video signal is applied, leakage will occur through the OFF resistance of the TPT and the resistance of the liquid crystal layer, but if both the TPT and the liquid crystal have sufficiently large resistances, the leakage will be slight.

The picture element electrodes and the TPTs connected to them are arranged in a matrix, and a scanning signal applied to the gate 6 turns on the TFTs in the horizontal direction all at once, writes a video signal from the source 4a to the picture element, and writes the video signal in the vertical direction. Images can be displayed by sequential scanning. The R, G, and B color filters 8a, 8b, and 8c are installed corresponding to each picture element electrode, and the amount of light transmitted through each picture element of R2O and B can be arbitrarily controlled by voltage. R,G,
Full-color display is possible by additive color mixing of B.

However, the conventional method requires a step of forming black stripes 10 that partition the R, G, and B color filters, in addition to the step of forming the color filters.

The black stripe 10 is usually formed from blackened chromium (chromium + chromium oxide) or black dye, but this has the disadvantage of increasing cost and decreasing yield. ) An object of the present invention is to provide a color liquid crystal display device which can eliminate the conventional drawbacks, simplify the process of forming black stripes that partition color filters, and can be manufactured with high yield.

(Structure of the Invention) The color liquid crystal display device of the present invention has a liquid crystal layer sandwiched between a first substrate and a second substrate facing each other, and has three types of red, green, and blue on the facing inner surface of at least one of the substrates. A large number of color filters are arranged in a predetermined arrangement, and each of the color filters is divided by a light-absorbing stripe formed by overlapping red and blue color filters, and corresponds to the red, green, and blue color filters. The liquid crystal layer has a different thickness, and a voltage is applied to the liquid crystal layer to modulate light.

Further, the thickness of the color filter is different for red, green, and blue.

(Description of Embodiment) An embodiment of the present invention will be described based on FIGS. 2 to 4.

FIG. 2 is a sectional view of a panel portion of the color liquid crystal display device of the present invention, and the numbers of each part are the same as in FIG. 1. Its operation is also the same as the conventional example.

What should be noted in FIG. 2 is that the portion corresponding to the conventional black stripe is formed by overlapping R and B color filters.

The formation method is as follows: First, R color filters are selectively formed on the picture element part corresponding to the conventional R and the part corresponding to the black stripe.6 Next, the R color filter is selectively formed on the picture element part corresponding to the conventional R and the black stripe. A B color filter is formed on the corresponding portion, and finally a G color filter is formed on the picture element corresponding to G. As a result, the portion corresponding to the conventional black stripe becomes a structure in which R and B color filters are superimposed. At this time R,
The film thicknesses of the R, G, and B color filters must be adjusted so that the thicknesses dR, d, dB of the liquid crystal layer corresponding to each of the G and B color filters are optically optimized values. Must be. This is to compensate for the optical rotational dispersion of the TN liquid crystal. (Details on this can be found in Japanese Patent Application No. 59-1655.
(See No. 2).

Figure 3 shows the spectral transmission characteristics of each of the R, G, and B color filters, and Figure 4 shows the spectral transmission characteristics of two of these color filters superimposed. It is something that

As is clear from Figure 4, a superimposed R and B color filter absorbs light over the entire range of visible light (λ = 400 μm to 700 μm), so R
It can be said that the superposition of B and B sufficiently fulfills the function of a black stripe.

In addition, the black stripes formed by the overlapping of R and B color filters not only improve color separation and increase contrast, but also serve as a light-shielding layer for TPT, and are effective due to the photoconductive effect. It is possible to prevent the TPT switching function from deteriorating and ensure good display performance.

Although only a color liquid crystal display device in combination with TPT has been described here, it is also applicable to a so-called simple matrix case in which it is combined with nonlinear elements such as MOS-FET, MIM, and varistor.

Further, the present invention can also be applied to color liquid crystal display devices, which are made by combining color filters and liquid crystals, regardless of whether they are of a transmissive type or a reflective type.

(Effect of the invention) As explained above, according to the present invention, R, G.

R the black stripe that divides the color filter of B.
, G, and B color filters, it is possible to simplify the process, reduce cost, and suppress a decrease in yield.

In addition, the black stripe part has a two-layer structure of R and B color filters, which has excellent light absorption characteristics over the entire visible light range, which improves normal color separation and contrast. As well as the original function of stripes.

In a liquid crystal display device combined with a TPT, the black stripe shields the TPT from light, prevents the switching function of the TPT from deteriorating due to the photoconductor effect, and has the effect of ensuring good display performance.

Furthermore, with such a configuration, by appropriately adjusting the film thicknesses of the R, G, and B color filters, the thickness of the liquid crystal layer corresponding to each of the R, G, and B color filters can be set to an optically optimum value. , which has the effect of compensating for the optical rotational dispersion of TN liquid crystal and providing a color liquid crystal display device with excellent contrast and color reproducibility6.

[Brief explanation of drawings]

FIG. 1 is a plan view of a panel portion of a conventional color liquid crystal display device, FIG. 2 is a sectional view of a panel portion of a color liquid crystal display device according to an embodiment of the present invention, and FIG. 3 is a view of a color filter of R2O,B. Spectral Transmission Characteristic Diagram FIG. 4 is a spectral transmission characteristic diagram obtained by superimposing two types of R, G, and B color filters. 1-TN liquid crystal, 2a, 2b ・= alignment film, 3a, 3
b - transparent electrode, 4a... source, 4b...
Drain electrode, 5... Semiconductor, 6... Gate, 7... Insulating film, 8a, 8b, 8c...
Color filter, 9a, 9b...transparent substrate, 10
...Black stripe.

Claims (2)

[Claims] (1) A liquid crystal layer is sandwiched between a first substrate and a second substrate facing each other, and a large number of three types of color filters of red, green, and blue are arranged in a predetermined arrangement on the opposing inner surface of at least one of the substrates. Each of the color filters is divided into light-absorbing stripes formed by overlapping red and blue color filters, and the liquid crystal layers corresponding to the red, green, and blue color filters have different thicknesses, and each of the color filters has a different thickness. A color liquid crystal display device that modulates light by applying a voltage to a liquid crystal layer. (2) The color liquid crystal display device according to claim (1), wherein the color filters have different thicknesses for red, green, and blue.