JPH0740102B2 - Active matrix liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an active matrix type liquid crystal display device for color display.

(Prior Art) In recent years, attention has been focused on a method of forming a thin display device using a thin film transistor matrix. In this method, image information is stored in each dot of the thin film transistor matrix provided on the substrate, and the image information is stored at a position corresponding to each dot of the liquid crystal layer, EL layer or EC layer provided on the matrix substrate. It tries to get a screen by displaying on. As a result, it was the mainstream of conventional display devices.
In principle, it is possible to realize a display device that is much thinner than that using a CRT. In addition, since the CRT display device causes high-energy electrons to collide with the fluorescent substance, the emission time is on the order of milliseconds, and the full screen is not displayed, so there is flicker noise, etc. was there. On the other hand, a display device using a transistor matrix displays almost all the time, and a more natural screen than a CRT can be obtained. Furthermore, it has features such as obtaining a flat screen and being compact and lightweight because no vacuum area is required.

FIG. 6 shows a basic structure of a transistor matrix array, that is, an active matrix substrate. Display screen is vertical m
This matrix is divided into a matrix of n lines and n columns, and is divided into m · n display pixels in total. Memory circuits C11, C12, ..., C with switching transistors at each intersection of the matrix
ij, ..., Cmn are formed, and the image information of each pixel is stored therein. Then, according to this image information, display is performed in a region corresponding to each pixel of the liquid crystal layer formed on the active matrix substrate.

A specific memory circuit having a simple structure as shown in FIG. 7 is used. This is because the size m · n of the matrix becomes large in order to obtain a high-definition display screen, and a simpler circuit is desired in order to manufacture a matrix circuit with high yield. In FIG. 7, Tij is a switching transistor, LC is a liquid crystal layer, and Cs is a capacitor that stores an image signal. The gate of the transistor Tij is connected to the i-th address line Xi, and the source is connected to the j-th data line Yj. Signal voltages of V (Xi) and V (Yj) are supplied to the address line and the data line, respectively. When a signal for turning on the transistor is input to the address line Xi, the transistor is turned on and the image signal prepared for the data line Yj is stored in the capacitor Cs. The liquid crystal layer LC is driven according to the stored image signal. Note that the transistors Ti1, Ti2, ... On the address line Xi are all turned on at the same time, and the image signals prepared for the data lines Yi, Y2 ,. It will be written in Ci2, ....

FIG. 8 schematically shows the timing of writing the image signal in the pixels Cij, Ci + 1, j. In the image signals .phi.ij, .phi.i + 1, j shown in FIG. 8, the solid line shows the ideal operation timing. That is, the writing of the image signal of the pixel Cij starts at time ti1, the writing ends at ti1 + ΔT, the gate voltage V (Xi) becomes zero at the same time, and the next image signal is again written to the pixel Cij at time ti2. Means that φij will retain its voltage level.

The above is the operation principle of the flat panel display device using the active matrix substrate of FIG.

By the way, in such a display device, as a transistor material, single crystal, polycrystal or amorphous Si is used.
Polycrystalline materials such as CdSe, Te and CdS are used. Particularly in recent years, a polycrystalline semiconductor material and amorphous Si (a-Si), which are used in a low temperature process, have been attracting attention in order to realize a large-sized and low-cost active matrix substrate.

In such an active matrix type liquid crystal display device, color display is possible. Red (R), green (G), and blue (B) color filters are provided on a counter electrode substrate that faces the active matrix substrate with a liquid crystal layer in between.
Color display can be easily performed by aligning this filter with each pixel of the active matrix substrate. As the arrangement of the color filters, there are a stripe-shaped arrangement as shown in FIG. 9A, a mosaic-shaped arrangement as shown in FIG. In order to improve the spatial resolution, it is desirable to substantially reduce the color arrangement interval l of each pixel of R, G and B, and in this sense, FIG. 9B is better than FIG. 9A. Is excellent.

However, considering the case where characters are displayed in the arrangement shown in FIG. 9 (b), when the substantial display dots that form a set of R, G, and B are made into a square shape of 2 × 2 pixels, the color balance is The display becomes unnatural due to the irregularity of the unit pixels. Even if an external drive circuit tries to remove this unnaturalness, the circuit becomes very complicated, and the problem is in the color filter arrangement, so a basic solution is difficult.

In this respect, in the pattern of FIG. 9A, by using 3 × 3 pixels as basic display dots, it is possible to display characters that are easier to see. However, this requires nine unit pixels for each RGB basic display dot, which causes problems of resolution and reduction of information amount in the display panel.

(Problems to be Solved by the Invention) As described above, the conventional active matrix type liquid crystal display device has a problem that it is difficult to perform easy-to-read color character display without lowering the resolution and the amount of information.

An object of the present invention is to provide an active matrix type liquid crystal display device which solves such a problem.

[Configuration of the Invention] (Means for Solving the Problems) In the active matrix type liquid crystal display device according to the present invention, the unit display dot area of the active matrix substrate does not include an address line and a data line,
It is characterized in that at least three display electrodes for R, G and B are arranged.

(Operation) In the conventional configuration, since one display electrode is arranged in the area sandwiched between the adjacent address lines and data lines, the color filter arrangement is as shown in FIG. 9 (a) or (b). Therefore, it was impossible to achieve both color balance and resolution in character display. On the other hand, in the present invention, in order to configure one display dot by arranging the display electrodes for R, G, B between the adjacent address lines and data lines,
Any of R, G, and B can be displayed within this one display dot. Therefore, the shape of the display dot is square,
Moreover, by setting the areas of the three display electrodes to be equal to each other, it is possible to improve the color balance when displaying characters. Moreover, since one display dot is composed of three display electrodes, there is little reduction in resolution and information amount.

Further, in the present invention, the data line to which two of the three display electrodes arranged in the display dot are connected,
By sharing the data line to which the other one is connected between the adjacent display dots, the number of data lines arranged between the adjacent display dots is alternately set to 1 in the address line direction.
Since the number of data lines is two, the number of data lines can be reduced.

(Example) First, a reference example of the present invention will be described.

FIG. 1 equivalently shows a schematic configuration of an active matrix substrate of one reference example. In the figure, G (Gi-1, Gi, Gi + 1,
...) is an address line, D (Di-1, Di, Di + 1, ...) is a data line that intersects with the address line. The address line Gi is connected to the gates of a plurality of TFTs in the i-th row, and the data line Di is It is connected to the drains of the TFTs in the i-th column. R in the figure,
Areas indicated by G and B are display electrodes, and they are independent T
It is connected to the source of the FT and aligned with the R, G, B color filters provided on the counter substrate (not shown).

As shown in the figure, three display electrodes of R, G, B are arranged in a square shape with the same area as a whole, and display dots P (Pi, i, Pi, i + 2, Pi + 2, i, Pi + 2, i + 2) are arranged. , ...) are configured. Hereinafter, this will be referred to as a trio display dot. There are no address lines and data lines in the trio display dots P, and two address lines G and two data lines D are arranged between each trio display dot P. Therefore, the R, G, B display electrodes in each trio display dot P are independently selected by a specific address line and data line.

FIGS. 2A and 2B show the structure of a more specific active matrix substrate of a reference example. (A) is a plan view of one trio display dot Pi, i portion in FIG. 1 and its surrounding address line and data line portion, and (b) is its A-
It is an A'cross section figure. Reference numeral 1 denotes a transparent glass substrate, on which address lines 2 which also serve as a gate electrode and are made of a Mo film having a thickness of 1500Å are arrayed. After this, a 1500 Å-thick CVD SiO ₂ film 3 is deposited on the entire surface as a gate insulating film, and then an a-Si film 4 is deposited thereon. The a-Si film 4 is patterned while being left in each TFT section as shown in the figure. After this I
R, G, B display electrodes using transparent conductive film such as TO 5 _R , 5 _G , 5 _B
Is formed. Within one trio display dot, the three display electrodes 5 _R , 5 _G and 5 _B are patterned so that they have the same area and become square as a whole. After that, by vapor deposition and patterning of the Al film, the data line 6 and the a-Si from the data line 6 are formed.
The drain electrode 6'extending on the film 4 and a-Si
A source electrode 7 is formed so as to extend from the film 4 to the display electrode. Finally, the organic passivation film 8 is formed, and the openings 9 of the trio display dot portions are formed in the organic passivation film 8 to complete the active matrix substrate.

A display device can be obtained by facing a counter electrode substrate with a color filter aligned with a display electrode to the active matrix substrate configured as described above and enclosing a liquid crystal therein.

According to this reference example, the trio display dots that form a set of R, G, and B display electrodes have a square shape suitable for character display,
In addition, the display electrodes have the same area and are controlled independently.

Therefore, compared to the conventional example, it is possible to display characters with good color balance and easy to see. Further, the shape of the trio display dots can be a rectangle other than a square, that is, a rectangle, or the area of each display electrode can be appropriately selected according to the display intensity, whereby the color balance can be appropriately set. it can. Moreover, regarding the spatial resolution, it is the same as the case where one display dot is composed of 2 × 2 pixel electrodes in the case of using the conventional FIG. 9 (b), and it is 3 in the case of using the FIG. 9 (a).
Higher resolution can be obtained as compared with the case where one display dot is composed of × 3 pixel electrodes.

In addition, in this reference example, there is no wiring in the trio display dots, so the display electrode spacing in the trio display dots is narrow,
Moreover, there are two wirings between the trio display dots, and the spacing is large. This also makes the character display easier to see. Further, in this reference example, as shown in FIG. 3A, the distance la between adjacent display electrodes in one trio display dot area can be made smaller than the wiring distance and the wiring-display electrode distance lb. This is because the display electrode spacing la is determined by the exposure etching process of one conductor layer. Then, within the range L ₁ of one trio display dot, 3 lb + la is required as the distance between the electrode and the wiring. On the other hand, in the conventional example in which the wiring and the display electrodes are alternately arranged, FIG.
As is clear from the above, when the display dot is composed of two pixels, the distance between the electrode and the wiring is 4 lb within the range L _{2 of the} display dot. Therefore, the display area can be increased in this reference example. Further, since one opening on the display electrode is also provided on the three electrodes, the effective display area is large.

FIG. 4 shows various examples of the arrangement of display electrodes and color filters when the trio display dots are arranged. These may be appropriately used depending on the purpose and purpose of use.

Further, for example, in FIG. 1, the slender display electrodes in the trio display dots may be divided into upper and lower parts so that they are independently controlled by different TFTs. In this case, one color filter may be opposed to the two divided display electrodes. With this structure, the spatial resolution becomes higher, which is particularly useful for video display and the like.

Next, examples of the present invention will be described. FIG. 5 shows the structure of an embodiment in which the number of data lines is reduced, corresponding to FIG. First
In the figure, two data lines are provided for one trio display dot, whereas in this embodiment, two data line portions and one data line portion are alternately arranged to form one trio. There are effectively 1.5 data lines per display dot. It is clear that the same effect as the above-mentioned reference example can be obtained also by this. Moreover, since the number of data lines arranged between adjacent display dots is alternately set to one and two in the address line direction, there is an advantage that the number of data lines can be reduced.

Further, the display quality can be improved by adopting a structure in which light is shielded by a black organic film, a metal film, or the like except for the openings of the active matrix substrate.

[Effects of the Invention] As described above, according to the present invention, it is possible to display color characters with good color balance and reduce the number of data lines, without causing a decrease in spatial resolution and the amount of information. Thus, the active matrix type liquid crystal display device can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an equivalent circuit of an active matrix substrate of one reference example of the present invention, FIGS. 2 (a) and 2 (b) are diagrams showing a concrete structure example thereof, and FIGS. 3 (a) and 3 (b). ) Is a diagram for explaining the effect of this reference example in comparison with a conventional example, FIGS. 4 (a) to 4 (c) are diagrams showing several examples of display electrodes and color filter arrangements according to the present invention, and FIG. Is a diagram showing an active matrix substrate of another embodiment in an equivalent circuit manner, FIG. 6 is a basic equivalent circuit diagram of an active matrix type liquid crystal display device, FIG. 7 is a diagram showing a configuration of a memory circuit portion thereof, and FIG. Is also a timing diagram for explaining the display operation,
(A) and (b) are diagrams showing an example of a color filter arrangement in a conventional color display.

Claims (6)

[Claims] 1. A plurality of address lines, a plurality of data lines intersecting with the address lines, a thin film transistor controlled by a selected address line, and a data signal from the data line is applied through the transistor. In the liquid crystal display device using the active matrix substrate in which the display electrodes that are integrated are formed, three display electrodes corresponding to three display colors are formed without including the address line and the data line in one display dot. An active matrix type liquid crystal display device, characterized in that the number of the data lines arranged and wired between adjacent display dots is one and two alternately in the address line direction. 2. The active matrix type liquid crystal display device according to claim 1, wherein the display dot area having the three display electrodes is rectangular. 3. The active matrix type liquid crystal display device according to claim 1, wherein the display dot area having the three display electrodes is square. 4. The active matrix type liquid crystal display device according to claim 1, wherein the areas of the three display electrodes are set to be equal in a display dot region including the three display electrodes. 5. The active matrix type liquid crystal display device according to claim 1, wherein the three display electrodes arranged in the display dots correspond to red, blue and green display colors, respectively. 6. Two of three display electrodes arranged in the display dots are connected to one of two data lines wired between adjacent display dots, and the remaining one is an adjacent display dot. The active matrix type liquid crystal display device according to claim 1, wherein the active matrix type liquid crystal display device is connected to one data line.