JPH071357B2 - Color display device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a color display device capable of color display with good image quality.

[Background of the Invention]

Conventionally, a cathode ray tube has been widely used as a device for displaying characters, figures, or TV images, but in recent years, a dot matrix type using liquid crystal or EL has been available because of the advantage that the depth of the display device can be made thin. Display devices have come to the fore. However, in the case of this dot matrix type display device, when the number of dots (pixels) is increased in order to obtain a resolution equivalent to that of a cathode ray tube, especially in the case of a time division type liquid crystal display device, crosstalk occurs and the contrast of the image remarkably increases. Getting worse. In order to prevent this, a so-called active matrix type display device in which a switching element such as a thin film transistor (hereinafter abbreviated as TFT) and a thin film diode is attached to each pixel has been proposed and developed.

As a concretely related prior art of this kind of display device, Nikkei Electronics September 10, 1984, no.351, p.
pp. 211-240 is known, which introduces the technology of a flat color display device having a switching thin film transistor (TFT) in a liquid crystal color panel.

That is, as shown in the plan view of FIG. 8, the switching transistor 3 is arranged in the vicinity of the intersection of the gate line 1 and the drain line 2, and the pixel 4 surrounded by the gate line 1 and the drain line 2 is arranged. It is driving. For this reason, the intervals between the pixels 4 are not uniform, and the distance is short on the side where the transistor 3 is absent and long on the side where the transistor 3 is present. Therefore, when each pixel 4 is distributed to three color filters of red (R), green (G), and blue (B), there is a problem that the color mixture is different between the side with the transistor 3 and the side without the transistor 3. . Further, when the color filters R, G, and B are arranged in a stripe pattern, the same color is arranged in the vertical direction, so that there is a problem that vertical lines are conspicuous. Further, similarly, when the color filters R, G and B are arranged in a mosaic pattern, since the same color is diagonally arranged, there is a problem that the diagonal lines are conspicuous.

[Object of the Invention]

It is an object of the present invention to provide a color display device in which color mixing due to the arrangement of the three color filters R, G and B is made uniform.

Another object of the present invention is to provide a color display device capable of obtaining a color image with good image quality by disposing color filters R, G and B of three colors.

[Outline of Invention]

According to one embodiment of the present invention, by defining a pixel region centering on an intersection of a gate line and a drain line, a color display device is provided in which color mixing is uniform and image quality is good.

Example of Invention

 Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining one embodiment of a color display device according to the present invention, in which FIG. 1A is a plan view and FIG.
FIG. 3 is a cross-sectional view when the 1B-1B line in FIG.

In the figure, SUB1 is a glass substrate having a thickness of about 1.1 [mm], and GATE is a gate electrode made of Cr or the like. AS
Is amorphous Si, and a film GI that acts as a gate insulating film of a field effect transistor (FET) is formed between the gates GATE. SD1 and SD2 are a pair of source / drain electrodes, and are formed on the silicon film AS with a space therebetween, and the gate electrode GATE straddles them. The pair of source / drain electrodes SD are both called source / drain electrodes because the source / drain in operation are switched when the bias polarity of the circuit is changed, that is, they are bidirectional like a normal FET. The source / drain electrodes SD are N ⁺ (high donor impurity concentration) amorphous S from the bottom.
It has a three-layer structure of i, Cr and Al. The N ⁺ -Si electrode layer reduces the contact resistance with amorphous Si, and the Cr electrode layer is the Al electrode layer.
Used to prevent reaction with layers. PSV is a protective film, which protects the FET from moisture and the like, and is formed of a SiO ₂ film or a Si ₃ N ₄ film having high transparency and good moisture resistance. ITO is a transparent conductive film connected to one of the source / drain electrodes SD (SD2) and acts as one electrode of the liquid crystal display device. The other source / drain electrode SD1 is also used as a wiring running in the Y direction. In addition, the gate electrode GATE runs in the X direction also as a wiring layer. LS is a light-shielding film that prevents external light from entering the gate region, which is the heart of the FET, and is made of a Cr material or the like. This FET has a small resistance between the source and drain when the gate electrode is positively biased with respect to the source electrode, and exhibits a large resistance when the gate bias is close to zero.

FIG. 2 shows the manufacturing method of this TFT.

First, after cleaning the glass substrate SUB, Cr is formed into a thickness of about 1,000Å by sputtering or the like. Next, the Cr film is selectively etched by a photo processing technique, and the gate electrode / wiring is patterned as shown in FIG. 2A.

Plasma chemical vapor deposition (CVD: Chemical Vapor Depositio)
n) method is used to form a Si ₃ N ₄ film with a thickness of about 1,000 to 4,000Å (Fig. 2B). Subsequently, amorphous Si is deposited by plasma CVD technology to a thickness of about 1,000 to 4,000Å.
Next, phosphorus-doped amorphous Si is deposited to a thickness of 400 to 2,000Å. This amorphous Si layer and phosphorus-doped amorphous silicon are formed by a dry etching technique or the like.
It is patterned as shown in FIG. 2C.

A Cr film and an Al layer are successively formed with a thickness of 600, 2,400Å, respectively, and these films are immersed in different etching solutions,
It is continuously patterned (FIG. 2D). At this time, the amorphous silicon doped with phosphorus is also etched by the same mask.

Transparent conductive film ITO is about 600 ~ 2,000Å by sputtering method etc.
And is patterned by photolithography (FIG. 2E).

The protective film PSV is formed to a thickness of about 0.5 to 2 μm by depositing a Si ₃ N ₄ film by a plasma CVD method.

The light-shielding film LS is deposited and patterned to a thickness of about 1,000Å by the same method as the above-mentioned gate electrode GATE (FIG. 2F).

In the present application, one pixel and one dot refer to the minimum unit of the screen. For example, in a color display device using three color components of red, green and blue, the minimum display element of each color is Pixel (Coined word for picture cell: Pixell)
Called.

In one pixel plane pattern PIX1 shown in FIG. 1A, the gate GATE and the drain electrode SD1 intersect in the area of the pixel electrode PIX formed of the transparent conductive films ITO1 and ITO2, and the thin film transistor TFT is formed at this intersection. This thin film transistor TFT is formed so as to be surrounded by the area of the pixel electrode PIX, and is designed so that the vertical and horizontal arrangement pitches are almost the same, and the dot size is vertical and vertical.
In the case of the same monochrome display in the horizontal direction, the pattern may be arranged in the row and column directions as it is.

FIG. 3A shows a pattern in which pixel plane patterns PIX1 are arranged in the X and Y directions. FIG. B shows a plan view when the red, green, and blue horizontal stripe filters R, G, and B are arranged. In the figure, a solid line hatching portion on the left lower side, a dotted line hatching portion on the right lower side, and a two-dot chain line cross are shown. The hatched areas indicate the areas that appear to shine red, green, and blue on the pixel electrode ITO, respectively. In this case, one pixel plane pattern PIX1 constitutes one pixel (dot).

FIG. 3C shows a sectional view when the 3C-3C line in FIG. 3B is taken as a cut surface. In the figure, the liquid crystal LC is enclosed between the upper and lower glass substrates SUB1 and SUB2, and the orientation of the liquid crystal molecules is determined by the upper and lower alignment films ORI2 and ORI1. PSV2 is a protective film made of acrylic resin. FIL is a color filter. ITO2 is a common transparent electrode facing the plurality of pixel electrodes ITO1 arranged.

Such a display body is assembled by separately laminating the substrate SUB1 side and the SCB2 side, and then enclosing a liquid crystal.

First, stacking on the substrate SUB1 (lower plate) side is performed as follows. A polymer resin is applied on the TFT mounting substrate manufactured by the process shown in FIG. 2 by a spinner or the like, and then an alignment film ORI1 is formed by rubbing or the like.

On the other hand, on the substrate SUB2 (upper plate) side, a color filter is formed on the glass substrate SUB2, and a protective film PSV2 is further formed thereon. The common electrode ITO2 is deposited on the protective film PSV2 by sputtering or the like, and finally the alignment film ORI2 is formed in the same manner as the alignment film ORI1.

The liquid crystal LC is enclosed between the upper and lower laminated substrates thus manufactured, and the polarizing plates POL1 and POL2 are mounted on the outer sides of the substrates SUB1 and SUB2, respectively.

4A, 4B and 5 show an equivalent circuit of the liquid crystal display (LCD) panel (PNL) thus formed and its peripheral drive circuit. LVS is an LCD vertical scanning circuit and applies a scanning switching signal to the gate electrode of the TFT. LHS is an LCD horizontal scanning circuit, and sequentially and selectively applies a video signal to the source / drain electrodes SD1 of the TFT.

With such a configuration, the thin film transistor TFT is formed at the intersection of the gate electrode GATE and the drain electrode SD1, and the pixel electrode PIX is formed so as to surround the transistor TFT. Therefore, the distances between the pixel electrodes PIX adjacent to each other are equal on all sides, and the color mixture is uniform.

FIG. 6 is a plan view showing another embodiment of the color display device according to the present invention, in which the same parts as those in the above-mentioned figures are designated by the same reference numerals. In the figure, a thin film transistor TFT defined by the same gate electrode GATE and the same drain electrode SD1
The pixel electrodes PIX are each composed of two sets of thin film transistors TFTA, TFTB and pixel electrodes PIXA, PIXB, which are arranged in a staggered manner. That is, a pair of thin film transistors TFTA and pixel electrodes are diagonally arranged with the intersection of the gate electrode GATE and the drain electrode SD1 as the center.
The first pixel plane pattern PIX1 made of PIXA and the second pixel plane pattern PIX2 made up of another set of thin film transistors TFTB and pixel electrodes PIXB are gate electrodes.
Pixels (dots) composed of one pixel plane pattern PIX3 are arranged by sharing the GATE in common. FIG. 7 shows the pattern diagram. Further, red, green and blue horizontal stripe filters R, G and B are arranged in each pixel plane pattern PIX3.
In this case, the filters R, G, B are arranged in a staggered pattern as shown in FIG.
Red horizontal stripe filters R of the same color are arranged in PIX1 and PIX2, respectively, and are periodically arranged. Red, green and blue signals are input to the drain electrodes SD1R, SD1G and SD1B, respectively.

According to such a configuration, one pixel plane pattern
PIX3 has a first pixel plane pattern PIX1 and a second pixel plane pattern PI with the gate electrode GATE being diagonally common.
Since they are arranged in a staggered pattern as X2, there is no difficulty in seeing vertical lines in the stripe arrangement of the filters R, G, B or diagonal lines in the mosaic arrangement. In addition, the drain electrode SD
Since 1 is provided for each of red, green and blue, driving becomes easy. Furthermore, one pixel plane pattern PIX3 has two thin film transistors TFTA, TFTB and a pixel electrode PIXA,
The presence of PIXB also reduces the extent of pixel defects due to thin film transistor failure.

〔The invention's effect〕

As described above, according to the present invention, by defining the pixel region with the intersection of the gate line and the drain line as the center, the uniformity of color mixture is improved and the array of the same color is linearly biased. Since it is eliminated, an extremely excellent effect such as providing a color image that is easy to see can be obtained.

[Brief description of drawings]

1 to 5 are views for explaining an embodiment of a color display device according to the present invention, FIGS. 6 and 7 are views for explaining another embodiment of the present invention, and FIG. [Fig. 6] is a diagram showing a conventional example. SUB, SUB1, SUB2 ... Glass substrate, GATE ... Gate electrode, FET ...
Field effect transistor, GI ... Gate insulating film, SD ... Source / drain electrode, SD1 ... Drain electrode, SD2 ... Source electrode, ITO, ITO1, ITO2 ... Transparent conductive film, LS ... Light shielding film, AS ... Amorphous Si layer, PSV1, PSV2 ... Protective film, ORI1, ORI2 ... Alignment film, LC
... Liquid crystal, FIL ... Filter, POL1, POL2 ... Polarizing plate, LCD ... Liquid crystal display, PNL ... Panel, TFT, TFTA, TFTB ... Thin film transistor, PIX, PIXA, PIXB ... Pixel electrode, PIX1, PIX2, PIX
3 ... Pixel plane pattern, LHS ... LCD horizontal scanning circuit, LVS
... LCD vertical scanning circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Shimada, 3300 Hayano, Mobara, Chiba, Chiba Prefecture, within the Mobara Plant, Hitachi, Ltd. (72) Kenkichi Suzuki, 3300, Hayano, Mobara, Chiba, Hitachi, Ltd., within the Mobara Plant, Hitachi, Ltd.

Claims (1)

[Claims] 1. A plurality of pixels each having a pixel electrode, a thin film transistor having a source electrode connected to the pixel electrode, and a color filter showing one of the three primary colors are arranged in a matrix, and every two rows. A plurality of scanning lines connected to the gates of the transistors are arranged between the two rows, the drain of the transistor located in an odd row of a column and the drain of the transistor located in an even row of the adjacent column. A plurality of signal lines connected to and are arranged so that each of the signal lines is connected to the pixel that belongs to the same color, and that each of the three primary colors is repeated in each row at a pitch of three. , One of the three primary colors is selected for each pixel, so that the diagonally located pixels of the same color are connected to the same scan line and the same signal line. display apparatus.