JPH0333724A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve the picture quality by arranging thin film transistors(TFT) which are driven with gate pulses applied to respective gate lines and picture element electrodes which are connected to the TFTs on both ends of the respective gate lines. CONSTITUTION:A TFT which is driven by a gate line 13 and a picture element electrode of nearly the same size are arranged on both sides of the gate line 13. Then a TFT and a picture element electrode of nearly the same size which are driven at the same time are arranged on both sides of each data line 14 and a color filter of size corresponding to those four picture elements is made to correspond. Then an electrode line for a holding capacity element formed in the same process with the gate wiring is provided between the gate wiring and gate wiring which adjoin to each other. Consequently, a picture element arranging method which has redundancy is realized with the simple constitution and the picture quality is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique that is effective for improving image quality when applied to liquid crystal display devices, particularly active matrix liquid crystal display devices in which pixels are composed of thin film transistors and pixel electrodes. .

[Conventional technology]

Active matrix type liquid crystal display device.

As shown in FIG. 2, it has a liquid crystal display section in which a plurality of unit pixels are arranged in a matrix. Each unit W element 1 of the M product display section is arranged in an intersection region of two adjacent gate signal lines and two adjacent gator lines. Here, the term "unit pixel" is used to mean a group of pixels that are addressed simultaneously.

In the case of color display, each unit pixel corresponds to a color filter of one color. Here, gate line 2 is in the column direction (horizontal direction)
Data II3 extends in the row direction (vertical direction) intersecting the gate line, and is arranged in a plurality in the column direction.

Each unit pixel described above is composed of a liquid crystal, a transparent pixel electrode 4 disposed with the liquid crystal interposed therebetween, a common transparent pixel electrode, a thin film transistor (TPT) 5, and the like. A transparent pixel electrode and TPT are provided for each pixel.

TPT source electrode 6° drain? The pole 7 and gate line! Pole 8 is transparent #electrode 4. A charge storage capacitor element 11 is formed between an 8-pixel electrode section connected to the data line 3 and gate line 2 and an adjacent gate line. Data line 3. The gates [2 each have a signal wI operating open circuit 9
A desired signal is applied from the vertical scanning circuit 10.

As liquid crystal devices as described above become larger, short circuits between the drain and source of the TPT and between the gate and source become more likely to occur due to foreign matter during the manufacturing process. These 6 short-circuited elements are so-called point defects (loss of unit pixel)
As the size of each pixel increases, point defects such as those described above are becoming more noticeable.

As a countermeasure to this problem, a method of designing one pixel portion redundantly has been proposed so far.

FIG. 3 is a method disclosed in Japanese Patent Application No. 62-242363, in which one pixel is divided into a plurality of TFTs and 111 poles. Further, FIG. 4 shows a method in which one pixel is made up of four sub-vixels.

The latter method is described in the International Display Research Conference 198δ Combination Record, page 56, CIDRC.

'88, Conference, Record,
(1988) p. 56).

[Problem to be solved by the invention]

However, in the above-mentioned prior art, in the former method, if one point, for example, point B in FIG. 3, is destroyed, all three divided Is become inoperable, and complete redundancy was not necessarily achieved. In addition, in the latter method, two gate lines are driven at a time, so if a storage capacitor element is provided and is also used as a gate line as shown in FIG. 3, noise will be generated due to the capacitance of the storage capacitor element.

There is a problem that the difference occurs between the pixels connected to the two gate lines, and it is not easy to provide a storage capacitor element.

Furthermore, in both of the above conventional techniques, there is a problem in that it is difficult to separately provide electrode wiring exclusively for the storage capacitor element without changing the manufacturing process from the viewpoint of the aperture ratio.

The aim of the invention is to overcome the above-mentioned problems.

In other words, we have realized a pixel arrangement method with redundancy with a simple configuration, we have also made the electrode wiring for the storage capacitor element, which is effective in improving image quality, so that it does not affect the drive waveform, and we have achieved an extremely high aperture ratio. The purpose is to form and arrange without reducing the

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as described in the claims.

That is, in the present invention, a TPT and a pixel electrode of approximately the same size are arranged on both sides of each gate line to be driven by the gate line. In addition, TPTs and pixel electrodes of approximately the same size are arranged on both sides of each data line so that they are driven simultaneously. Furthermore, a color filter of a size corresponding to these four pixels is provided. These make it possible to divide the unit pixel into four units arranged as shown in FIG. 1, for example.

In the present invention, in order to improve image quality, as shown in FIG. 6, an electrode line for a storage capacitor element, which is formed in the same process as the gate wiring, is further provided between adjacent gate wirings.

[Effect]

According to the above-mentioned means, TPT in each unit pixel
Even if the pixel is locally destroyed, it is not a point defect of the entire unit pixel, so it is possible to reduce point defects of the pixel. In this respect, the operation partially overlaps with the method shown in FIG. However, compared to the fact that one unit pixel becomes defective due to the destruction at point B in FIG. 3, the method of the present invention avoids this risk.
Fully redundant.

Furthermore, according to the above means, it is possible to provide a dedicated line for storage capacitor element electrodes without changing the conventional process, so that the voltage holding characteristics applied to the liquid crystal can be improved and uniformity of display image quality can be ensured. This is an extremely advantageous pixel arrangement when considering that the number of wirings in the column direction is the same as in the method shown in FIG.

〔Example〕

(Example 1) An example of the present invention will be described below with reference to FIG. 1st
Figure (a) is a plan view of a single color pixel portion of an active matrix color liquid crystal display device. Here, the unit pixel is composed of four TFTs (TFTI to TFT4) and a pixel Mf11. Also, A- in Fig. 1(a)
FIG. 1(b) shows a cross-sectional view taken along cutting line A, and FIG. 1(c) schematically shows a structure in which a plurality of unit pixels shown in FIG. 1(a) are arranged. It is.

The liquid crystal display device includes, on the surface of the lower transparent glass substrate 18,
An rti element having TPT and a transparent pixel electrode ITO 12 is configured.

Each color portion consists of four TPTs of substantially equal size and four pixels f connected to each of them, as described above.
It is composed of I& poles, and each is arranged symmetrically with respect to the gate line 13 and data line 14. In other words, as shown in FIG. 1(a) and CQ), a gate line extending in the column direction and a plurality of gate lines arranged in the row direction, and a gate line extending in the row direction and arranged in a plurality in the column direction. Pixels to which driving waveforms are applied almost simultaneously are arranged on both sides of each data line.

Each of TFTI to TFT4 mainly has a gate electrode 15. Gate insulating film 23. i-type semiconductor layer.

It is composed of a pair of source electrode 16 and drain electrode 17.

The gate electrode is made of chromium Cr formed by sputtering, for example.
It is made up of a T-shape and protrudes as part of the gate wiring. The thickness was about 1000A.

The gate insulating film is formed using, for example, a silicon nitride film formed by plasma CVD to a thickness of about 3000 Å.

The i-type semiconductor layer includes thin film transistors TPTI to TFT4.
is used as a channel forming region for each. Regarding the four pixels that make up a unit pixel.

This i-type semiconductor layer is composed of a common island region 18. i
The type semiconductor layer is formed of an amorphous silicon or polycrystalline silicon film, and is formed to have a thickness of about 200 to 3000 layers.

By forming the i-type semiconductor layers of a plurality of transistors into a common island-like pattern as described above, there are two locations where the drain wiring can cross over the i-type semiconductor M step. In this case, the number of point defects occurring within a pixel can be reduced to 174.

Further, the i-type semiconductor layer is provided to extend between the data line and the gate line at an intersection (crossover section). This structure reduces short circuits between the data line and the gate line.

The source electrodes and drain electrodes of the thin film transistors TPTI to TFT4 are provided separately on the i-type semiconductor layer. The source electrode and the drain electrode are each configured such that when the bias polarity of the circuit changes, the source and drain are interchanged in operation. In other words, TFT is FE
Like T, it is bidirectional.

The source electrode and the drain electrode have a double electrode structure of Cr and Al1, and are formed in the same process. Further, the drain electrode 17 is configured integrally with the data 14m.

Transparent conductive L4 (indium/tin oxide film ITO) formed by sputtering so as to partially overlap the source electrode 16
12, a transparent pixel electrode is formed with a film thickness of 1000 to 2000 degrees (in this example, 12 degrees).

A protection 11120 is formed to cover the entire screen area of the lower substrate formed as described above, and a color filter 2 is formed.
A liquid crystal display panel is completed by combining it with a normal 9° liquid crystal 21 formed on the counter substrate 2 and the like.

In the 1st!1 (0), 411! from the above 4 pixels! This figure shows the red (R), green (G), and blue (B) arrays of the affected unit pixels. Each of these KGB patterns forms a color filter 22 pattern of a predetermined color on the counter substrate corresponding to the four lines shown in FIG. 1(a). Some of the point defects are smaller than the entire area of the unit pixel (in this example, 1
74 area), the point defects can be made difficult to see. Furthermore, since the four pixels are formed to have substantially the same size, the area of point defects within the pixel can be made uniform.

Furthermore, compared to the conventional division method shown in FIG. 3, the local destruction of TPT is 1 unit! A more complete redundancy can be achieved since the risk of being linked to a defect in the i-line is avoided.

Another advantage of this embodiment is that by arranging pixels that are driven simultaneously on both sides of the data line, the data line can be formed substantially linearly in the row direction. The RGB arrangement pattern is a so-called 3 self-recording sequence, which provides good image visibility. Comparing this with the conventional technique shown in FIG. 3 in which the data line meanderes, it is possible to reduce the wiring resistance of the data line to 273 or less.

The number of lines can be reduced to 172, the number of intersections between gate lines and data lines can be reduced to 172, and the yield can be improved to a distant degree.

In this example, an RGB triangular array is used, but a vertical stripe array as shown in FIG. 1(d) can also be used without compromising redundancy.
Needless to say, it can also be applied to other machine stripe arrangements.

FIG. 1(e) shows an improvement of the first embodiment of the present invention.

In this embodiment, the pixel configuration will be explained using (f).

The arrangement is exactly the same as the first embodiment, and the only difference is that some of the gate lines and data lines are made into two layers.

These can be accomplished by adding a step of forming another gate wiring pattern 103 after forming the gate line 13, and a step of forming another data wiring pattern 104 after forming the gate line 14.

The double-layered wiring pattern as described above has the effect of relieving defects caused by disconnection.

Although the additional patterns 103 and 104 are made narrower than the original patterns 13 and 14 in this case, it goes without saying that the above effect will not be lost even if they are made wider.

Furthermore, in this embodiment, double layering is avoided at the gate portion of the TPT, and this is to prevent step breaks in wiring, electrodes, etc. at wiring intersections and TFT portions.

This part can also be made into two layers if necessary.

(Example 2) A plan view of the single color pixel portion of a liquid crystal display device according to a second example of the present invention is shown in FIG. 5. In the same figure, the gate pattern corresponding to the hatched area is excluded. Only this point differs from FIG. 1(a). According to this, it is possible to reduce the overlapping area between the gate line and the data line, and it is possible to reduce the inter-wiring capacitance and the short-circuit probability between the wirings.

(Example 3) A third example of the present invention will be described using FIG. 6. 6th
Figure (a) is a schematic diagram corresponding to Figure 1 (CQ). A storage capacitance element line 24 is provided at. These storage capacitor element lines 24 constitute the other electrode that forms the storage capacitor 11 between the pixel electrodes of each pixel on both sides of each line.

The storage capacitor element line 24 is formed in the same manufacturing process as the gate wiring 2. That is, for example, it is possible to form the Cr storage capacitor element wiring patterns at the same time as the Cr gate wiring pattern, so there is no need to change the conventional process, and it is of course possible to provide similar storage capacitor lines using the conventional method.

However, in that case, considering that the area between the gate line and the storage capacitor line provided in parallel will reduce the aperture ratio, and problems such as shorting between the gate line and the storage capacitor line will occur, this method is not suitable for pixel arrangement. Needless to say, is more desirable.

The gate insulating film 23 left on a predetermined portion of the lower substrate may be used as the dielectric film of the storage capacitor element 11. The size of the storage capacitor element is as shown in FIG. 6(b). A desired size can be obtained by changing the overlapping area between the line electrode and the ITO pixel electrode.

Each storage capacitor element line 24 is electrically kept at a constant potential 1, for example, equal to the voltage of the counter electrode Vcom.

The storage capacitor element as described above is effective in retaining charge in each pixel, and can improve display uniformity of a liquid crystal display device. Also, unlike the conventional example shown in FIG. 3, the storage capacitor element line in this example is a dedicated line and does not double as a gate line. This has the effect of reducing the contribution from

(Example 4) A fourth embodiment of the invention is shown in FIG.

This embodiment shows a different arrangement method in terms of the relationship between pixel arrangement and the location where the TPT is provided.

This embodiment is similar to the first embodiment in that pixels driven by the gate line are arranged on both sides of each gate line, but the method of connecting the drain electrodes is different.

Needless to say, even in this case, the redundancy due to color pixel division is not impaired.

In this embodiment, two color signals are applied to each data line for each gate line. The combination of the two colors changes every two data lines.For example, in FIG. 2nd group, 3rd group. 4th group, 5th group. (RI B) l (as R) for the sixth set of data lines, respectively.

(B, R) signals are added.

Although the above method involves complication in the scale of the two color mixing circuits, it has the effect that even if one data line is disconnected, 1/2 of each unit pixel can be lit, and defects can be repaired.

Furthermore, as shown in FIG. 7, another effect can be obtained when the inputs to the data lines are shaped like a comb and are driven from above and below the panel. That is, since half of the same unit pixel is driven by the upper and lower drive circuits, the difference between the upper and lower analog signal outputs due to manufacturing variations in the ICs in the output stage of the upper and lower drive circuits is absorbed.

This has the effect of reducing longitudinal streak defects.

(Embodiment 5) FIG. 8 is a diagram showing a fifth embodiment of the present invention, and shows a block configuration diagram of a television receiver.

It is used to display TV images.

In FIG. 8, 25 is a standard drive circuit used in ordinary color TVs. Furthermore, if the input to the video signal processing circuit is a V'l'R signal, it can also be used as a video monitor.

Note that as the liquid crystal display section, those described in Examples 2 to 4 can be used.

Furthermore, in this embodiment, the liquid crystal display device of the present invention is not limited to displaying TV images, but can of course be used as other displays. In particular, if the present invention is applied, it is possible to realize a screen that is much better than that of the past in large-screen, high-definition display devices, and it is possible to clearly display precise figures and small characters, so information It is suitable as a display device such as a computer terminal device or a character-two-figure display device.

Although the present invention has been described above with reference to the embodiments, the main purpose of the present invention is to divide the pixel into two parts, and is not limited to the above-mentioned embodiments. and its anodized film may be used, TP
The structure of T is not limited to the above, and if there is a margin, it may be the same as 4 above.
3rd V for each divided pixel! Of course, conventional techniques such as j may also be applied.

〔Effect of the invention〕

As explained above, according to the present invention, the following typical effects can be obtained.

Point defects in pixels of a liquid crystal display portion of a liquid crystal display device can be reduced, and uniformity of display image quality can be maintained.

The present invention can be achieved with a simple configuration without changing the conventional process described above.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention and a liquid crystal display device improved therefrom, FIGS. 2 to 4 are diagrams for explaining conventionally known examples, and FIGS. 5 to 7 are diagrams for explaining a conventionally known example. FIG. 8, which is a diagram for explaining another embodiment of the present invention, is a block diagram of an example of an application device of the present invention. 1...Unit pixel, 2...Gate line, 3...Data line, 4°12...Transparent image 111tl [i, 5...
・TFT, 6, 16... Source electrode, 7, 17...
Drain wtm, 8, 15... Gate electrode, 11...
- Holding capacitor element, 9... Signal drive circuit, 10... Vertical scanning circuit, 24... Holding capacitor element line. 2 Figure (L) 2 1st 1U (C) Tomikazu (e) NoZ Figure 1st Sen No. 5 Mifuzu (Mukazumen (1)) Abusive picture

Claims (1)

[Claims] 1. A plurality of gate lines extending in the column direction and arranged in the row direction, a plurality of date lines extending in the row direction and arranged in the column direction, and their respective intersection areas. A liquid crystal display device having a pixel composed of a thin film transistor and a pixel electrode, and having a signal drive circuit that applies a signal to be displayed to the data line, and a vertical scanning circuit that applies a gate pulse to the gate line, wherein the plurality of A liquid crystal display characterized in that, for each of the gate lines, the thin film transistor driven by a gate pulse applied to each gate line and the pixel electrode tangential to the thin film transistor are arranged on both sides of each gate line. Device. 2. In the liquid crystal display device according to claim 1, for each of the plurality of data lines, an image signal applied to one data line is almost simultaneously transmitted to a plurality of pixels, and the plurality of pixels A liquid crystal display device characterized in that the liquid crystal display device is arranged on both sides of each of the data lines. 3. In the liquid crystal display device according to claim 1 or 2, the above-mentioned electrode is provided substantially parallel to the gate line and between each of two adjacent gate lines of the plurality of gate lines; A capacitor electrode line is formed at a position that divides the space between the two gate lines at approximately equal intervals, and in each pixel, a storage capacitor element is formed in which the pixel electrode is used as one electrode and the capacitor electrode line is used as the other electrode. A liquid crystal display device characterized by: 4. The liquid crystal display device according to claim 1, wherein the thin film transistors disposed on both sides of each gate line and the pixel electrodes connected thereto have substantially the same size. A liquid crystal display device. 5. In the liquid crystal display device according to any one of claims 1 to 4, at a position opposite to a plurality of pixels to which the same data signal is transmitted almost simultaneously, there is provided a liquid crystal display device having a size including the plurality of pixels. A liquid crystal display device comprising a color filter formed by disposing a film of a predetermined color. 6. A television image display device, characterized in that the liquid crystal display device according to any one of items 1 to 5 above is used as a display means. 7. An information terminal device or character/graphics display device, characterized in that the liquid crystal display device according to any one of the above items 1 to 5 is used as a display means. 8. A liquid crystal display device according to any one of claims 1 to 7, characterized in that the gate line is composed of two conductor layers. 9. A liquid crystal display device according to any one of claims 1 to 8, wherein the gate line is constructed of two conductor layers.