WO1998008134A1

WO1998008134A1 - Liquid crystal display device

Info

Publication number: WO1998008134A1
Application number: PCT/JP1997/002862
Authority: WO
Inventors: Naoto Hirota
Original assignee: Obayashiseikou Co., Ltd.
Priority date: 1996-08-19
Filing date: 1997-08-18
Publication date: 1998-02-26
Also published as: JP3567183B2; TW406206B; JPH1062802A

Abstract

In order to obtain pictures to which angle of visibility can be specified excellently and which are free from residual images, gradation inversion, flickers, and cross-talk with an active matrix type liquid crystal display device of a lateral electric field system, the display device is constituted in such a way that display picture elements composed of scanning signal lines (1), video signal lines (2), picture element electrodes (3, 4), and active elements (T) are constituted on a substrate and a liquid crystal-oriented film is formed on the substrate directly or an insulating film in between. Then the substrate is faced to a color filter substrate carrying another liquid crystal-oriented film so that a liquid crystal layer can be held between the substrates, and the electrodes (1, 2, 3, and 4) and active element (T) are constituted so that an electric field which is substantially parallel with the substrates can be impressed upon the liquid crystal layer. The electrodes (1, 2, 3, and 4) and the element (T) are connected to an external control means which can arbitrarily control the impressed electric field in accordance with a display pattern and a polarizing means which changes the optical characteristic of the liquid crystals in accordance with the oriented state of the crystals is provided. The distances (a, and b) between the liquid crystal driving electrodes (3) and the common electrodes (4) are made to be different from each other.

Description

Liquid crystal display device

Technical field

The present invention relates to a large screen active matrix type liquid crystal display device having a wide viewing angle and high image quality.

Background art

A method of applying an electric field to a liquid crystal composition layer using a pair of comb electrodes formed on one substrate of a conventional active matrix type liquid crystal display device is disclosed in, for example, JP-A-7-36058 and JP-A-7-159786. In the following, a display method proposed in Japanese Patent Application Laid-Open No. 6-160878 is referred to as a horizontal electric field method, even if the main electric field applied to the liquid crystal composition layer is in a direction substantially parallel to the substrate interface.

Fig. 1 and Fig. 2 show examples of the conventional lateral electric field method. The liquid crystal drive electrode (2), which is a comb-shaped pixel electrode, and the common electrode (3) are linearly arranged in parallel, and the distance between the electrodes (3) and (4) The separations a are all the same.

透過 The transmittance characteristics of the electric field type liquid crystal cell with respect to the driving voltage are as follows. When a voltage higher than the voltage shown in ':) is applied, the brightness decreases: The video signal voltage seems to be slightly too high. In such a case, the gradation of the image is inverted. 喈 In the gradation display characteristics, this gradation inversion is a very big problem, resulting in an extremely unnatural image display.

In a horizontal electric field type liquid crystal display device, the liquid crystal driving voltage tends to be higher than that in a conventional vertical electric field type τ crystal display device. C also required high-voltage output, resulting in high costs.

Furthermore, the alignment film and the liquid crystal used in the horizontal electric field type liquid crystal display device must be combined with a fringe angle of 1 degree or less, which is around 4 to 7 degrees used in the conventional TN liquid crystal display device. Alignment film cannot be used. For this reason, if a horizontal electric field type liquid crystal display device is to be manufactured on a conventional T ^: liquid crystal display device production line, it is necessary to change the material of the alignment mask and the liquid crystal material, resulting in lower production efficiency. On the color filter substrate: well, like the conventional 従来 Τ Ν liquid crystal display, Also, the color filter and substrate have a transparent conductive film on the entire surface, unlike conventional liquid crystal display devices, so they are susceptible to the effects of static electricity. There are two problems:

The processing of pixel electrodes used in liquid crystal display devices of the in-plane switching method is often performed by jet etching, and the distance between the electrodes cannot be made very small.Therefore, the response speed of the liquid crystal is higher than that of the conventional TN liquid crystal. And it was difficult to handle video:

The present invention has been made to solve these problems, and an object of the present invention is to provide a horizontal electric field liquid crystal display device with no grayscale inversion, good viewing angle characteristics, a low-voltage driving IC, and a high response speed. Further, it is to increase the degree of freedom in selecting a usable liquid crystal composition and an alignment film material, and to improve the liquid crystal process (the yield is improved and the cost is reduced). Disclosure

In order to solve the above problems and achieve the above object, according to the present invention, the following means are formed on a substrate at each intersection of a scanning signal wiring, a video signal wiring, and the scanning signal wiring and a video signal wiring. An active matrix substrate having a thin film transistor, a liquid crystal drive electrode connected to the thin film transistor, and a common electrode at least partially formed to face the liquid crystal drive electrode; and an active matrix substrate facing the active matrix substrate. A counter substrate, and a liquid crystal display device comprising a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate,

(Means 1) The inter-electrode distance between the liquid crystal drive electrode and the common electrode is not uniform within one pixel, but a combination of two or more types of inter-electrode distance.

[Means 2] In the means 1, the distance between the liquid crystal drive electrode and the common electrode is two or more types within the pixel, and the distance between the electrodes is different from the center of the pixel as a boundary. Arranged symmetrically—

[Means 3] The common electrode is connected in the direction in which the video signal wiring extends, and within the effective display screen, the common electrode is not connected to each other across the video signal wiring. [Means 4] In Means 3, the common electrodes connected to the video signal wiring extending in all directions are separated into an odd group and an even group, and the odd group and the even group are shared according to the period of the scanning signal. A voltage waveform having a phase opposite to that of the common electrode is applied to each of the electrodes, and a video signal waveform having a phase opposite to that of the common electrode is applied to each of the liquid crystal driving electrodes facing the common electrodes of the odd and even groups. A liquid crystal display device characterized by a driving method.

L means 5j In a liquid crystal display device of the transverse field type, the liquid crystal driving electrode and the scanning signal wiring and the power are obtained from the additional capacitance formed by overlapping the liquid crystal driving electrode and the common electrode via the insulating film; The structure was such that the additional capacitance formed by being superposed through the insulating film was larger:

[Means 6] In the means 5, the potential of the common electrode is fixed, and the liquid crystal drive electrode is supplied with a positive or negative video signal voltage with respect to the potential of the common electrode again by 1 L according to the period of the scanning signal. And the liquid crystal composition layer; a capacitive coupling drive for applying a signal waveform also to the scanning signal wiring which is superimposed on the liquid crystal drive electrode via an insulating film so as to be higher than the applied voltage. ^^: For liquid crystal display

[Means 7] In a lateral electric field type liquid crystal display device, an impurity is doped into a thin film semiconductor layer, activated to lower the resistance, and used as a liquid crystal drive electrode.

ίMeans 8 J In the means 7, the structure is such that the video signal wiring and the pixel pole are bent at an angle of 1 ° to 1 ° with respect to the liquid crystal direction.

[Means 9] In the means 7, the scanning signal wiring and the pixel electrode are arranged so as to be bent at an angle of 1 ° to ± 45 ° with respect to the liquid crystal alignment direction.

(Means 10) In the means 7, the video signal wiring and the pixel electrode are arranged so as to be bent in a range from 45 degrees to 135 degrees except 90 degrees with respect to the liquid crystal alignment direction.

Means 1 1] In the means 7, the scanning signal wiring and the pixel electrode are arranged in a structure in which the scanning signal wiring and the pixel electrode are bent in a range of 45 ° to 135 ° except 90 ° with respect to the liquid crystal alignment direction:

: Means 12] In a horizontal electric field type liquid crystal display device, a layer formed on a counter substrate covers one layer of a filter: A high resistance U 0 'i2' cm-i (wide Ω-cm):

[Means] The liquid crystal display according to the invention 12, characterized in that the total thickness of one color filter, one layer of the liquid crystal layer and the liquid crystal layer is at least twice the distance between the liquid crystal drive electrode and the common electrode. Equipment—

[Measure 14] In an in-plane switching mode liquid crystal display device, an insulating film is used as an overcoat layer covering one layer of a power filter formed on a counter substrate, and a boundary between the R, G, and B power filters is formed. A conductive or semiconductor electrode was formed as a black mask on the overcoat insulating film.

[Measure 15] In the manufacturing process of the in-plane switching type liquid crystal display device, an alignment film for aligning the liquid crystal is applied, and after baking, the alignment film is subjected to V irradiation. The rubbing treatment was performed after the ion irradiation and plasma treatments such as,, (, etc., to reduce the LCD tilt angle to 1 degree or less.

<Means 16> In Means 3, common electrodes connected in the direction in which the video signal wiring extends are separated into an odd group and an even group, and the power video signal wiring is divided into two vertically at the center of the screen. :

[Means 17] In the means 16, the scanning signal wires divided into two groups at the center of the surface are divided into upper and lower groups, and are simultaneously driven by the upper and lower groups. By applying video signal voltage waveforms of opposite phase to the group and applying the voltage waveform of the video signal wiring and the common electrode drive waveform of opposite phase to the odd and even groups of common electrodes, BEST MODE FOR CARRYING OUT THE INVENTION A liquid crystal display device characterized by a driving method in which different video signals are written in two horizontal lines above and below a liquid crystal display device.

As in the above means 1 and 2, when the distance between the liquid crystal drive electrode and the common electrode is not uniform in one pixel 內, but is composed of a combination of two or more kinds of electrode distances, FIG. As shown in Fig. 3, even if the shortest distance between the electrodes is inverted, even if the grayscale inversion occurs at the widest distance between the electrodes, inversion occurs. As shown in Fig. 5, Fig. 8, Fig. 10, If the distance between the electrodes is symmetrical or symmetrical up and down from the center of the element, increase the distance between the electrodes closest to the scanning signal wiring and video signal wiring. The result is a uniform image with little crosstalk:

By means 3 and 4, a 5 V drive video signal drive IC that can reduce the video signal drive voltage of the dot inversion drive method to less than half even in the horizontal electric field type liquid crystal display device can be used. As shown in Fig. 16 and Fig. 17, the dot inversion drive does not generate horizontal cross and vertical cross talk, so that good image quality can be obtained. In addition, as shown in Fig. 13, the common electrode connection part completely covers the TFT part, which prevents light from entering the F-cho, so the black mask on one side of the color filter is omitted. By eliminating the black mask on the CF side, the aperture ratio can be increased, the brightness can be increased, and the liquid crystal panel can be made.

By means 5 and 6 above, it is possible to reduce the video signal drive voltage of the horizontal line inversion drive method to less than half even in the horizontal electric field type liquid crystal display device-as shown in Fig. 21, Fig. 27 and Fig. 29. In addition, it is necessary to apply a special drive signal waveform to the common electrode in order to control the potential of the liquid crystal drive electrode using this capacitance by forming a large capacitance between the liquid crystal drive electrode and the scanning signal wiring via the insulating film. In other words, the common electrode potential only needs to be fixed to a potential close to the median value of the video signal voltage. In the conventional horizontal line inversion driving method, the entire common electrode is driven by the video signal waveform according to the period of the scanning signal wiring. The resistance value of the common electrode had to be reduced because it was driven with a voltage waveform of the opposite phase to that of the common electrode.There was no flexibility in the material._ The entire common electrode had a large area overlapping the video signal wiring, and the overall capacitance In order to avoid this, there is a problem that the power consumption increases when driving. There was a problem that the number of pull-out terminals increased—an increase in the number of pull-out terminals caused an increase in the number of drives 1 C, an increase in IC cost, and an increase in connection failures. By driving the capacitively-coupled horizontal line inversion 」S” _w with the common electrode potential fixed as above, ultra-large liquid crystal display devices can be manufactured at low cost and with minimal increase in power consumption. In the case of the horizontal electric field method, which can be realized by the conventional method, unlike the conventional vertical electric field method, the capacitance formed by the scanning signal wiring and the liquid crystal driving electrode is determined by the capacitance formed by the common electrode and the liquid crystal driving electrode. For this reason, as shown in FIG. 41, the driving voltage amplitude V * of the scanning signal wiring can be reduced, so that the bias voltage applied to the TFT is also reduced and the characteristic shift of the TFT can be reduced. This makes it possible to lower the formation temperature of the gate insulating film of the thin film transistor (TFT), shortening the tact time when manufacturing large substrates, and reducing thermal distortion and thermal shrinkage of the substrates. Connection This makes it possible to reduce manufacturing costs.

By means 7 above, the liquid crystal drive electrode can be formed simultaneously with the formation of the thin-film transistor (TI "T) (;," Since the method of (1) is used, the miniaturization and processing accuracy can be much improved compared to the conventional processing method using the etching method. As shown in FIGS. 42, 43, FIG. 57, and FIG. By forming the liquid crystal driving electrode at the same time as the drain electrode, the problem of poor contact between the drain electrode and the liquid crystal driving electrode does not occur, and the processing accuracy of the distance between the liquid crystal driving electrode and the common electrode increases. The occurrence of brightness unevenness is reduced over the entire screen. Liquid crystal drive By processing both the electrode and the common electrode by dry etching, the distance between the electrodes can be reduced, and the liquid crystal drive voltage is reduced. It is possible to increase the response speed of the liquid crystal at the same time.

By using the above-mentioned means 7, 8, 9, 10, and 11, when a horizontal electric field is applied in the pixel electrode (part of the liquid crystal drive electrode and common electrode) as shown in Figs. In the conventional horizontal electric field method shown in Fig. 51, the liquid crystal molecules generate two kinds of rotational movements, left rotation and right rotation, inside the pixel electrode. As shown in Fig. 50, the viewing angle characteristic is shifted. Within a single pixel, two types of rotational movement of liquid crystal molecules, left rotation and right rotation, occur. In this case, even when the tilt angle is large, the characteristics of the viewing angle do not shift. Therefore, in the in-plane switching mode liquid crystal display device using the structure of the present invention, the tilt angle is not limited. This increases the degree of freedom in selecting the alignment film and liquid crystal. Uses the materials used in the conventional vertical electric field type liquid crystal self-process, such as the sealing material used in the liquid crystal process, the alignment film, and the injection port sealing material. Can increase the production efficiency and investment efficiency: The effective utilization rate of the polarizing plate also increases, so that the two-tone inversion that can reduce the cost can be prevented:

By using the above means 12, 13, and 14, even if there is no transparent conductor film (ITO) on the entire surface of the color filter, there is no electrostatic charge-up in the liquid crystal self-process, and the adhesion of the hearticle is reduced. to also be provided with resistance comparable to the present invention ^{(10 ¾ 0 * ^ ~10 "} Q 'ciri), the effect is increased Figure -. 15, 46, 47, 48, Fig.) As shown in, ，, ⑩, ，, ⑩ are Γ O, and a liquid crystal cell is completed by using a stacked layer of metal or metal or metal oxide or metal, a metal silicide, and a semiconductor layer with impurity-doping activity. Later, electrostatic damage from the outside can be completely prevented: high resistance layer overcoat: By using a layer, an inexpensive electrodeposition color filter can be used for the horizontal electric field type liquid crystal. Good flatness, no unevenness of the cell gear, It is possible to make cost cheap good liquid crystal panel of the scan door

By means 15 described above, it is possible to change the characteristics of the alignment film having a tilt angle of about 3 to 6 degrees, which has been conventionally used in a liquid crystal display device of the vertical electric field type, to reduce the tilt angle to less than〗 degrees. As described in (1), the viewing angle characteristics of a horizontal electric field type liquid crystal cell can be greatly improved by reducing the fringe tilt angle to 1 degree or less. Since the alignment film used can be used without changing it, it can be used by simply inserting one of the V-irradiation device, ion infra- structure device, or plasma surface treatment device into the conventional liquid crystal cell production line. It is possible to create an electric field type liquid crystal display device, which can increase production efficiency and investment efficiency: In addition, as shown in Fig. 5-1 and Fig. 55, by using masking processing, one pixel can be formed. , Two types of fret tilt angles It can be on the set Control of viewing angle characteristics is freed.

By means 16 and 17 above, even in the case of an ultra-high definition table (SXGA or XGA) in which the frame frequency and the scanning signal wiring increase, the scanning signal wiring can be lengthened twice, so that the electron transfer is slow. Amorphous thin-film transistors can also be used sufficiently: even if the image is enlarged, the length of the video signal wiring is reduced to 1 /, and the number of intersections between the scanning signal wiring and the video signal wiring is reduced to i / 2. This eliminates the problem of the resistance of video signal wiring, that is, the use of conventional metal materials eliminates the need to change the process. Use the same process as conventional VGA and SVGA display devices According to the present invention, dot inversion drive can be introduced for ultra-high-definition display, and a low-voltage drive IC can be used, so that the cost is low and there is no display unevenness. High quality images can be realized using amorphous silicon thin film transistors

【Example】

[Example 1] FIGS. 4 and 5 are a cross-sectional view and a plan view of a unit pixel of the present invention.

The scanning signal wiring (gate electrode) ① formed on 信号 is preferably made of an anodizable metal such as A 1, but it is better to use r, Mo, Ti, W, Ta. ヽ b A two-layer structure or a three-layer structure of Cu having a low electric resistance value and the refractory metal is used in a super-large display device. After forming the insulating film 非晶質, an amorphous silicon (a-Si) film is formed and used as an active active layer of the transistor: the video signal wiring ② overlaps a part of the amorphous silicon. Forming the drain electrode ©: In the case of Fig. 4, the drain electrode © and the liquid crystal drive electrode ④ are formed at the same time with the same metal material. The Si \ film and the Si0 _∑ film cover all of them. Next, the common electrode ③ is formed: Matrix of the above unit pixels Active matrix: An alignment film made of a polyimide is formed on the surface of a substrate, and a rubbing treatment is performed on the surface. An opposite substrate having an alignment film formed on the surface is also rubbed. And a liquid crystal composition containing rod-shaped liquid crystal molecules の間に between the active matrix substrates, and polarizing plates ⑩ and に disposed on the outer surfaces of the two substrates:

As shown in Fig. 5, the distance between the common electrode ③ and the liquid crystal drive electrode ④ has ^two types, a and b. In Fig. 5, the distances a and b between the electrodes are arranged symmetrically. 8 and 10, the number of electrodes is increasing, and the distance between the electrodes is also a combination of a and b, and a, b, and c, as shown in Figs. 7, 9, and 1. Combinations are considered to be symmetrical as in Figure 5, but symmetry is not always required:

As shown in Fig. 58, it can also be applied to the case where the distance between the common electrode ③ and the liquid crystal drive electrode ④ is set up and down. The types of distance between the electrodes are a, b, and c. It is possible to introduce more than just three types. _ In the case of Fig. 5, Fig. 6, Fig. 8, and Fig. 10, the liquid crystal molecules are easily affected by the electric field from the video signal wiring (2) Therefore, it is conventionally known that the crosstalk in the direction along the video signal wiring can be reduced by arranging the common electrode ③ so that は is sandwiched between them. It is good to set the distance a between the electrodes closest to the signal wiring a to the largest value._ In other words, if the distance between the electrodes is arranged under the condition of a> bc or a> c ≥ b, the crosstalk can be further reduced. '' The problem of grayscale inversion occurs when the video signal voltage is too high In particular, when the tilt angle of the liquid crystal is large, the grayscale inversion becomes easier when the tilt direction of the liquid crystal is more inclined than in the front direction. There is also a method of giving a slant or a positive and negative bretilt angle. The easiest way is to set the flailing angle to 0 (zero) degree: However, the rubbing orientation method used in mass production is However, the fret tilt angle cannot be completely set to zero degree, and a fret tilt angle of about 0.5 degree is inevitably generated. In a horizontal electric field type liquid crystal display device, it is particularly effective to set two or more values of the distance between electrodes in one pixel as in the present invention. 5 V or less Between the electrodes where the transmittance is maximized at It is good to arrange the electrodes by the combination of the interelectrode distance that maximizes the transmittance. According to the characteristics of Fig. 3, it is good to set the interelectrode distance to 5 μm and 7.5 / im with 5 V drive.

Embodiment 2 FIGS. 13 and 64 show unit pixels in which the common electrode is connected to the video signal wiring in the same direction and the common electrode is not connected to the video signal wiring across the video signal wiring inside the effective display screen. In FIG. 13, the connection portion of the common electrode covers the upper part of the thin-film transistor. In this case, the thin-film transistor semiconductor layer can be formed without a black mask (BM) on the color filter of the opposite substrate. Since no light penetrates, the leakage current does not increase when the thin film transistor is turned off. FIGS. 18, 19, 20, 20, 21, 22, and 23 show these unit pixels as: Fig. 20, Fig. 22, and Fig. 23 show the pixel electrodes parallel to the scanning signal wiring, but the connection direction of the common electrode is the same as the video signal wiring. Has become:

In order to realize such a planar arrangement, in the conventional cross-sectional structure as shown in FIG. 4, the scanning signal wiring 1 and the common electrode 3 are short-circuited. The cross-sectional structure as shown in Fig. 44 and Fig. 57 is required. In these cross-sectional structures, the common electrode is formed on the upper part of the substrate, and the protective insulating film below the common electrode and the upper insulating film ® are used. In addition, an oxide-based insulating film or organic insulating film having a small dielectric constant can be used, so that an increase in load when driving the scanning signal wiring can be minimized (Example 3) FIGS. 11 and 15 Is a plan view in which the common electrode connected in the same direction to the solid video signal wiring in Example 2 is connected and separated into an odd group and an even group outside the effective display screen. FIG. One set of books.Three books can be considered as one set and connected and separated into an odd group and an even group. Figure 59 is a plan view of the structural arrangement surrounding the entire effective display screen with the odd-numbered group connection electrodes @ and the even-numbered group connection electrodes, and the common connection electrodes, scanning signal wiring, and video signal wiring are static electricity. With this structure, the problem of static electricity failure in the liquid crystal self-process can be significantly reduced.This figure shows a common electrode separated into an odd group and an even group. Each phase is reversed according to the period of the scanning signal. Is much smaller than the conventional vertical electrode method, so the effect of the additional capacitance on the scanning signal wiring increases, and the voltage amplitude of _Vr (-) and Vr (+) can be reduced. As a result, the bias voltage applied to the scanning signal wiring (gate electrode) and the drain electrode of the thin film transistor is also reduced, and the characteristic shift of the thin film transistor is also reduced. Since the intersection area can be reduced, the horizontal line inversion driving method as in the present invention has the advantage of reducing the horizontal crosstalk. The video signal wiring driving circuit C can also reduce the signal amplitude and thus is inexpensive. V-power IC can be used.

[Embodiment 6] Fig. 12, Fig. 43, Fig. 44, Fig. 57, Fig. 64, Fig. 65, Fig. 24 show that the thin film semiconductor layer is doped with impurities and activated to lower the resistance, and as a liquid crystal drive electrode 3A and 3B are a cross-sectional view and a plan view of a unit pixel according to an embodiment of the present invention: A scanning signal wiring (gate electrode) 1 is formed on a glass substrate 2, and a gate insulating film 2 is formed so as to cover this. From this, an amorphous silicon film is formed, and a continuous insulation film バ on the bath channel side is formed continuously without breaking the vacuum. The amorphous silicon film at this time has a film thickness of about 300 A to 700 良い. About 2000A is enough for the insulation film. · Except for the back channel protective insulating film ®, the other part is etched with a hydrofluoric acid based etchant to expose the surface of the amorphous silicon film. Risezu to PI _{I: 1} ion shower dough bi that is based on the gas ! 10 / U f 'about in grayed, is doped with phosphorus to the amorphous Shitsushi Rico emissions: Then excimer laser activation process Oko Nau according to one The one: instead of the ion shower de one Bing, the PH ₃ gas Phosphorus treatment may be used to adsorb phosphorus on the surface of the amorphous silicon layer, and then activate the melt diffusion of phosphorus when the silicon layer is melted by an excimer laser. The exposed area becomes a low-resistance holographic silicon layer: After the positive resist is stripped, the thin film transistor source and drain electrodes ㉜ and the liquid crystal drive electrode 同時に are simultaneously dry-etched. : The advantage of forming the liquid crystal drive electrode with a low-resistance polysilicon film is that it allows micro-hatching to be performed by this drilling— The liquid crystal display device, the response speed is made pointed out that slow, the liquid crystal drive electrode FIG. 9 is a drive voltage waveform diagram in which a video signal waveform having a phase opposite to that of the common electrode is applied to the liquid crystal drive electrodes facing the common electrodes of the odd-numbered group and the even-numbered group, respectively. FIGS. 16 and 17 are polar diagrams showing how the video signal pressure is written to the pixels having the structural arrangements of FIGS. 14 and 15 of the present invention. It is divided into plus and minus based on the common electrode potential. Such a writing drive method is called a dot inversion drive method. _{C With} this drive method, horizontal strokes do not occur and good images can be obtained. A large voltage can be applied to the liquid crystal phase by applying an SIE with a phase opposite to that of the video signal waveform to the common electrode. Can be reduced to less than 1/2. As a result, an inexpensive 5 V driven IC can be used, and the cost can be reduced.

Example 4 FIGS. 24, 27, and 29 show that the liquid crystal driving electrode ④ and the common electrode ③ scan with the liquid crystal driving electrode も more than the additional capacitance formed by superimposing the common electrode ③ via the insulating film. FIG. 4 is a plan view of a unit pixel in a case where an additional capacitance ⑯ formed by overlapping a signal wiring ① with an insulating film interposed therebetween is larger. Figure 30, Figure 31, Figure 32, Figure 33, Figure 34, and Figure 35 are plan views in which these unit plane elements are arranged in a stripe or delta arrangement. In order to realize these planar structures with good yield, it is desirable to use cross-sectional structures as shown in Figs. 12, 26, 28, 42, 44, 57, and 65. In order to further increase the additional capacitance formed by the liquid crystal drive electrode and the scanning signal wiring, a cross-sectional structure as shown in FIG. 66 may be used. The overlapping area of the liquid crystal drive electrode and the common electrode should be as small as possible.

Fifth Embodiment FIG. 41 is a timing chart of a scanning signal voltage waveform and a video signal voltage waveform for driving the in-plane switching mode liquid crystal display panel of the fourth embodiment. The scanning signal has a quaternary waveform. The common electrode potential is close to the median value of the video signal waveform and is fixed at the potential. The capacitance that applies the scanning signal voltage V r (one) or V r (+) to the liquid crystal composition through an additional capacitance formed by the liquid crystal drive electrode and the scanning signal wiring being superimposed via an insulating film. A coupling drive system is used. In a lateral electric field type liquid crystal display device, a capacitance between pixel electrodes formed between a liquid crystal driving electrode and a common electrode via a liquid crystal composition is used. As the distance between the electrodes and the common electrode is reduced to about 3, the response speed increases, and it is possible to respond to moving surfaces. If it is up to about 3 μm, it can be processed by conventional etching, but the control accuracy of line width is not sufficient in the case of etching. In that regard, reproducibility of processing accuracy in dry etching has already been proven by IC. Polysilicon doped with impurities is a material which is most suitable for large-screen liquid crystal display devices because it is a material that can be easily dry-etched. Next, after forming the video signal wiring ②, it is completely covered with the protective insulating film ⑥. The common electrode ③ is formed last, but this common electrode is also made of a material that can be processed by dry etching (such as high melting point metals such as Mo, Ti, Nb, Ta and their alloys or silicide compounds of these). As a result, it is possible to produce an in-plane switching liquid crystal display capable of high-speed response.

In Fig. 44, Mo is thinly formed by sputtering or ion plating on the drain electrode that has been laser-activated by doping impurities to further reduce the resistance, and MoSix ( FIG. 3 is a cross-sectional view of a case where molybdenum silicide is formed. In Fig. 57, after forming an amorphous silicon film doped with impurities by plasma CVD on the amorphous silicon film, the impurity amorphous silicon layer is changed to low-impurity polysilicon by excimer laser. It is sectional drawing at the time of changing to a layer. Molybdenum silicide is also one of the dry etching materials. Similar silicide is formed by sputtering not only Mo but also other refractory metals.

[Embodiment 7] Figs. 52, 19, 21, 31, and 33 show video signal wiring and pixel electrodes.

(The liquid crystal drive electrode and part of the common electrode facing the liquid crystal drive electrode) is a plan view of a structure in which the liquid crystal alignment direction is bent at an angle of ± 1 ° to ± 45 ° with respect to the liquid crystal alignment direction. is there. The dielectric anisotropy of the liquid crystal molecules is positive. As shown in Fig. 52, when a voltage is applied to the common electrode ③ and the liquid crystal drive electrode and an electric field is generated between the electrodes, the liquid crystal molecules を make two kinds of rotational movements, left rotation and right rotation, at the bent part. I do. Since two types of rotational movement are possible inside the unit pixel, the deviation of the viewing angle characteristic does not occur regardless of the magnitude of the pretilt angle. [Embodiment 8] Figs. 52, 20, 20, 22, 23, 32, 34, and 35 show that the scanning signal S-line and the pixel electrode move from ± 1 degree to ± 1 degree with respect to the liquid crystal alignment direction. It is a top view in the case of the structure bent in the 45-degree angle range. The dielectric anisotropy of the liquid crystal molecules is positive. As in the case of the seventh embodiment, two kinds of liquid crystal molecule rotation motions, that is, left rotation and right rotation occur inside the unit pixel. The deviation of the viewing angle characteristics does not occur regardless of the magnitude of the pretilt angle.

[Embodiment 9] Figs. 53, 19, 21, 31, and 33 show that the video signal and the surface element force are bent in the range of 45 to 135 degrees, excluding 90 degrees, with respect to the liquid crystal alignment direction. It is a top view in the case of a structure. The dielectric anisotropy of the liquid crystal molecules is negative. As shown in Fig. 53, when a voltage is applied to the common electrode ③ and the liquid crystal drive electrode され and an electric field is generated between the electrodes, the liquid crystal molecules 、 rotate left and right two ways around the bend. exercise. By allowing two types of rotational movement inside the unit pixel, the deviation of the viewing angle characteristics does not occur regardless of the magnitude of the pretilt angle.

[Example 10] Figs. 53, 20, 20, 22, 23, 32, 34, and 35 show scanning signal wiring, pixel electrodes, and force. FIG. 4 is a plan view of a structure bent in the range of FIG. The dielectric anisotropy of liquid crystal molecules is negative. As in the ninth embodiment, two kinds of liquid crystal molecule rotational motions, ie, left rotation and right rotation, occur inside the unit pixel. Regardless of the magnitude of the pretilt angle, the deviation of the viewing angle characteristics does not occur.

In each of the seventh, eighth, ninth and tenth embodiments, the rubbing treatment is performed so that the liquid crystal molecules at the interface with the upper and lower substrates are almost parallel to each other. The polarizing axis (optical axis) of the polarizing plate is arranged so as to be substantially orthogonal at both the top and bottom, and a normally black mode in which light does not pass from the surface element when no electric field is applied is used. As shown in Figure 36, Figure 37, Figure 38, and Figure 39, the black mask used for these color filters has the same angle as the angle at which the video signal wiring and scanning signal wiring are bent, and a part of the BM is bent. There is a special feature in what you do.

Embodiment 11 FIGS. 45, 46, and 47 are cross-sectional views of a color filter and a substrate of an in-plane switching mode liquid crystal display device. Color fill of R, G, B on glass substrate ⑪ Form a tar. Next, an organic or inorganic high-resistance material (Ιί ^ Ω'αι ^ ΙΟ ^ Ω'αη) is formed for flattening and preventing electrostatic charge during the liquid crystal process. As shown in Fig. 56, in the horizontal electric field method, there is an experimental result that the voltage holding ratio hardly decreases even if the liquid crystal specific resistance decreases to about 10 ⁹ Ω'cm. In Figs. 45 and 46, the transparent ITO is formed on the entire surface, and then the R, G, and B color filters are formed by the electrodeposition method. In this case, the sum of the thickness of the high resistance material, the thickness of one color filter, and the thickness of the liquid crystal layer is required to be at least twice the distance between the liquid crystal drive electrode and the common electrode. If the total thickness is more than twice the distance between the electrodes, the electric field generated between the liquid crystal drive electrode and the common electrode will be affected by the transparent conductive film (ITO) ⑩ formed on the entire surface of the color filter. It is possible to generate a transverse electric field in a direction parallel to the substrate without receiving much.

Example 12 FIGS. 48 and 49 are cross-sectional views of a color filter substrate of a liquid crystal display device of an in-plane switching mode. Form R, G, B color filters on the glass substrate ①. Next, an organic or inorganic insulating film @ is formed for planarization. In this state, various problems occur due to static electricity generated in the liquid crystal process. Therefore, a black mask is formed on the insulating film @ to further discharge static electricity. When a transparent conductive electrode ⑩ is formed, the same pattern as that of the black mask may be used.

As described in the eleventh and twelfth embodiments, if no conductive electrode is formed on the color filter one substrate side, the lateral electric field type liquid crystal display device is affected by an electric field due to external static electricity. A major problem arises that it cannot be converted. As shown in Fig. 67, there is a method of forming a transparent conductive film on the outside of the glass substrate on the color filter side. In this case, however, a high insulating filter layer or a flattening film is formed during the liquid crystal process. In some cases, the trapped static electricity cannot be removed while trapped, which causes poor alignment.

[Example 13] As shown in Figs. 50 and 51, if the liquid crystal drive electrode and the common electrode are simply arranged in parallel, the viewing angle characteristic is deviated when the pretilt angle of the liquid crystal is large. Resulting in. Used for conventional vertical electric field type liquid crystal display devices In addition, since the pretilt angle of the alignment film is as large as 3 to 7 degrees, the viewing angle characteristic is inevitably deviated. Polyimide after orientation film firing a pre-tilt angle by using the same alignment layer as a way of reducing the 1 degree or less, and UV irradiation treatment, He, Ne, Ar, N 2, 0 2 gas, such as ionized ion implantation Processing methods have been developed. There is also the same effect by plasma treatment using O ₂ gas using a reactive ion etching apparatus. By performing a rubbing alignment treatment after performing these treatments, the pretilt angle can be reduced to 1 degree or less, and the liquid crystal molecules can be uniaxially oriented. As shown in FIGS. 54 and 55, it is also possible to limit the above-mentioned V processing, ion plantation processing, and plasma processing to half of one pixel by using a mask using a photomask / photoresist. By using this embodiment, deviation of the viewing angle characteristic does not occur even when the conventionally used alignment film is used for a liquid crystal display device of a horizontal electric field type.

Embodiment 14 FIG. 62 shows that, as in Embodiment 2, the common electrode is connected to the video signal wiring in the same direction, and within the effective display surface, the common electrode crosses the video signal wiring. Not connected to each other. The common electrode is divided into an odd group and an even group, and the odd groups are connected to each other outside the effective display screen. The difference from the second embodiment is that the video signal wiring is divided vertically into two at the center. The terminals to be connected to the IC for driving the video signal wiring are also separated into two upper and lower parts, respectively, and the number of terminals is also doubled. If the number of scanning signal lines is greatly increased, as in GA for 0/8, the structure of this embodiment reduces the resistance of the video signal wiring and reduces the number of intersecting scanning signal lines. Is reduced by half, the coupling capacitance is reduced, and the driving load of the video signal wiring is greatly reduced.

Fifteenth Embodiment FIG. 63 shows a drive voltage waveform for driving the in-plane switching mode liquid crystal display device having the structure according to the fourteenth embodiment. Two scanning signal lines are operated simultaneously in the upper half area and the lower half area. Since the common electrode is connected in the upper half region and the lower half region, it is driven by a method in which the polarity is inverted in accordance with the driving cycle of the scanning signal wiring. The common electrode is divided into an odd group and an even group. Opposite-phase voltages having different polarities are applied to the odd-numbered group and the even-numbered group, which are connected to the common connection electrodes @ and ©, in reverse according to the period of the scanning signal wiring. The video signal wiring is divided into an odd-numbered group and an even-numbered group, and signal voltages of opposite phases with different polarities are applied to the corresponding common electrodes of the odd-numbered group and the even-numbered group. The odd-numbered and even-numbered video signal lines are divided into upper and lower halves, and different in-phase video signals are applied. This is a two-scan line simultaneous access dot inversion drive system. In the case of an OA display device such as a convenience store, a frame memory is provided, so it would be good to be able to extract image data for two run signal wirings from this frame memory at the same time. When the number of scanning signal wirings / frame frequency greatly increases as in SXGA and UXGA, the selection time of scanning signal wiring is reduced to 10 sec or less if the conventional one-scan signal wiring access method is used. In the following cases, the driving capability of the amorphous silicon thin film transistor is approached, and the video signal voltage cannot be accurately transmitted to the liquid crystal driving electrode. With the simultaneous scanning dot inversion drive method of the present invention, the selection time is twice as long as that of the conventional method, so that a sufficient video signal writing time can be secured even with an amorphous silicon thin film transistor. Also greatly expands the degree of freedom Industrial applicability

According to the present invention, firstly, it is possible to obtain an image having good viewing angle characteristics without grayscale inversion of the image. Secondly, an inexpensive 5 VIC can be used for the video signal drive IC, and a conventional liquid crystal member can be used, so that an inexpensive and highly reliable image display device can be provided. Third, it is possible to create a high-speed, in-plane switching IPS LCD that is not affected by external static electricity. Fourth, an ultra-high-definition large-screen liquid crystal display can be realized using amorphous silicon thin film transistors ^ [Explanation of symbols]

1——scan signal,

2——Video signal wiring

3--common electrode

4--LCD drive electrode

5——Gate insulating film

6—Protective insulating film

7—Liquid crystal alignment film (TFT substrate side)

8—Liquid crystal alignment film (opposite substrate side ... color filter substrate side)

9——Liquid crystal molecules (positive dielectric anisotropy liquid crystal)

10— T F T side glass substrate

11—Opposite glass substrate

12—— T F T Substrate side polarizing plate

13 --- Optical substrate side polarizing plate

14——Upper insulating film

15——Drain Snore

16——Storage capacitance formation area

17 --- Anodic oxide film

18—Common electrode (center line) formed simultaneously with the same material as the scanning signal wiring 19—Common electrode through hole

20—Common electrode (center line) through the common electrode through hole

21 --- Plac mask of color filter

22—Liquid crystal molecules (negative dielectric anisotropy liquid crystal)

23——Scan signal wiring drive waveform

24——Odd number video signal waveform

25——even-numbered video signal waveform

26—Odd number common electrode drive waveform —Even number common electrode drive waveform

—— (n—1) th scan signal wiring drive waveform

—— nth scan signal wiring drive waveform

——Video signal waveform

——Common electrode potential

——Poly-Si drain electrode activated and reduced in resistance after impurity ion implantation

—Drain electrode with metal silicide formed on activated poly-Si semiconductor layer after impurity ion implantation

——Drain electrode doped with impurity on non-doped amorphous silicon layer

——Black mask with anti-reflective coating

——Transparent conductive layer

——Color filter layer

——High resistance flattening film

——Resin black mask

——Black mask electrode with anti-reflective coating for antistatic

——Planarization insulating film

——Black mask electrode for antistatic

—Static element

——Odd number common electrode drive connection electrode

——Connecting electrodes for driving even-numbered common electrodes

——Connection electrode for static electricity

— Nth common electrode drive waveform

-Upper half area nth scan signal wiring drive waveform

——Lower half area nth scan signal wiring drive waveform

— Upper half area M-number video signal waveform

——Lower half area No.M video signal waveform —— No.M common electrode drive waveform

——Top half area video signal wiring —Lower half area video signal wiring ——Upper half area scanning signal wiring ——Lower half area scanning signal wiring —Additional capacitance contact through hole

A-- The angle at which the alignment direction of the P-type liquid crystal molecules intersects the pixel electrode (common electrode and liquid crystal drive electrode)

B — Angle at which the alignment direction of the N-type liquid crystal molecules intersects the pixel electrode (common electrode and liquid crystal drive electrode)

BP—Back channel side protective insulating film

P—Orientation direction of liquid crystal molecules and polarization axis direction of polarizer (optical axis)

Q——Polarization axis direction of polarizing plate (optical axis)

D—Transistor and drain electrode formed at the same time as video signal wiring S Poly-Si liquid crystal drive electrode with low resistance activated by laser annealing after ion implantation of S-impurity

T——Semiconductor layer

U——Low pretilt area rubbed by V irradiation

J——Liquid crystal drive electrode with metal silicide formed on impurity semiconductor layer poly-Si-formed by laser annealing after implantation of impurity ions K—Non-doped Doping impurity on amorphous silicon layer Semiconductor liquid crystal drive electrode

a —Distance between common electrode and LCD drive electrode

b——Distance between common electrode and liquid crystal drive electrode

c——Distance between common electrode and liquid crystal drive electrode

sc——Capacitor electrode for liquid crystal drive formed simultaneously with video signal wiring

Claims

The scope of the claims

1. A thin film transistor formed on a substrate at each intersection of the scanning signal wiring, the video signal wiring, the scanning signal wiring and the video signal wiring, a liquid crystal driving electrode connected to the thin film transistor, and at least a part of the liquid crystal driving electrode A liquid crystal display comprising: an active matrix substrate having a common electrode formed to face the electrodes; a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. In the device, the distance between the liquid crystal driving electrode and the common electrode is not uniform in one pixel, and is formed by a combination of two or more kinds of distances between the electrodes. Indicating device.

2. In claim 1, the distance between the liquid crystal drive electrode and the common electrode is two or more types within one pixel, and the different electrode distances are symmetrical or symmetrical with respect to the center of the pixel. A liquid crystal display device, wherein:

3 ₀ and a liquid crystal drive electrodes connected to the thin film transistor TFT formed at each intersection of the scanning signal lines on the substrate and the video signal wiring and the scanning signal lines and the video signal wiring, at least a portion, An active matrix substrate having a common electrode formed to face the liquid crystal drive electrode; a counter substrate facing the active matrix substrate; and a liquid crystal sandwiched between the active matrix substrate and the counter substrate. In a liquid crystal display device comprising a plurality of layers, the common electrode is connected to the video signal wiring in the same direction, and inside the effective display screen, the common electrode is not connected to each other across the video signal wiring. Display device.

Four. In claim 3, the common electrode connected in the direction to the video signal wiring is separated into an odd group and an even group, and the common electrodes of the odd group and the even group are divided according to the period of the scanning signal. A liquid crystal display characterized by applying voltage waveforms of opposite phases to each other and applying video signal waveforms of opposite phase to the common electrodes to the liquid crystal driving electrodes facing the common electrodes of the odd and even groups. apparatus. Five. A thin film transistor formed at each intersection of the scanning signal wiring, the video signal wiring, the scanning signal wiring and the video signal wiring on the substrate, and a liquid crystal driving electrode connected to the thin film transistor; An active matrix substrate having a common electrode formed to face the drive electrode; a counter substrate facing the active matrix substrate; and a liquid crystal consisting of a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. In the display device, the liquid crystal driving electrode and the scanning signal wiring overlap with each other via an insulating film, rather than an additional capacitance formed by overlapping the liquid crystal driving electrode and the common electrode via an insulating film. A liquid crystal display device characterized in that the additional capacitance formed by the operation is larger.

6. In claim 5, the common electrode potential is fixed, and the liquid crystal drive electrode is alternately written with a positive and negative video signal “1 £” with respect to the common electrode potential in accordance with the period of the scanning signal. In order to further increase the MIE applied to the liquid crystal composition layer, a capacitive coupling driving method is used in which a voltage signal waveform is also applied to a scanning signal wiring which is superimposed on a liquid crystal driving electrode via an insulating film. Liquid crystal display.

7. A thin film transistor formed on a substrate at each intersection of a scanning signal wiring, a video signal wiring, the scanning signal wiring and the video signal wiring, a liquid crystal driving electrode connected to the thin film transistor, and at least a part of the liquid crystal. A liquid crystal comprising: an active matrix substrate having a common electrode formed to face a drive electrode; a counter substrate facing the active matrix substrate; an active matrix substrate; and a liquid crystal layer sandwiched between the counter substrates. A liquid crystal display device, wherein a thin film semiconductor layer is doped with an impurity, activated and reduced in resistance, and used for a liquid crystal drive electrode.

8. 9. The liquid crystal display device according to claim 7, wherein the video signal wiring and the pixel electrode (the liquid crystal driving electrode and a part of the common electrode facing the liquid crystal driving electrode) have a force of ± 1 degree to ± 45 degrees with respect to the liquid crystal alignment direction. A liquid crystal display device characterized by a bent structural arrangement in an angle range.

9. 8. The liquid crystal display according to claim 7, wherein the scanning signal wiring and the pixel electrode are formed of a liquid crystal. A liquid crystal display device characterized by a bent structure arrangement in an angle range of ± 1 degree to ± 45 degrees with respect to the alignment direction.

Ten. 8. The liquid crystal display device according to claim 7, wherein the video signal wiring and the pixel electrode are bent in a range from 45 degrees to 135 degrees except 90 degrees with respect to a liquid crystal alignment direction. .

11. 8. The liquid crystal display device according to claim 7, wherein the scanning signal wiring and the pixel electrode are bent in a range of 45 degrees to 135 degrees except 90 degrees with respect to a liquid crystal orientation direction. .

12 ₀ and the scanning signal lines and the video signal wiring on the substrate, and the liquid crystal drive electrodes and thin film transistors formed at each intersection of the scanning signal lines and the video signal wiring connected to the thin film transistor, at least a portion the A liquid crystal comprising: an active matrix substrate having a common electrode formed to face a liquid crystal drive electrode; a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. In the display device, a high resistance material (Κ ^ Ω ′) is formed on an overcoat layer covering one color filter formed on the opposite substrate.

A liquid crystal display device comprising:

13. In Claim 12, the sum of the thicknesses of one color filter, one overcoat layer, and the liquid crystal layer is at least twice the distance between the liquid crystal drive electrode and the common electrode. A liquid crystal display device, comprising:

14. An insulating film is used as an overcoat layer covering the color filter layer formed on the counter substrate, and a conductive or semiconductor electrode is formed on the overcoat insulating film at the boundary between the R, G, and B color filters. A liquid crystal display device, characterized in that is formed as a black mask.

15. A thin film transistor formed on a substrate at each intersection of the scanning signal wiring, the video signal wiring, the scanning signal wiring and the video signal wiring, a liquid crystal driving electrode connected to the thin film transistor, and at least a part of the liquid crystal. An active matrix substrate having a common electrode formed to face the drive electrode; a counter substrate facing the active matrix substrate; In the process of manufacturing a liquid crystal display device comprising a liquid crystal layer sandwiched between the opposite substrates, an alignment film for aligning the liquid crystal is applied, and after baking, the alignment film is subjected to UV irradiation treatment or He, Ne, Ar, A manufacturing method characterized by reducing the liquid crystal pretilt angle to 1 degree or less by performing rubbing treatment after performing ion implantation treatment or plasma treatment of N ₂ , O _2, or the like.

16. Claim 3 is characterized in that the common electrode connected in the direction to the video signal wiring is separated into an odd group and an even group, and the video signal wiring is divided into upper and lower parts at the center of the screen. Liquid crystal display device.

17. In claim 16, in the center of the screen, the scanning signal wiring divided into two groups, upper and lower groups, are simultaneously driven by an upper group and a lower group, and the upper and lower video signal wirings include an odd group and an even group. Apply the opposite-phase video signal voltage waveforms to the odd and even groups of common electrodes, and apply the voltage waveforms of the video signal wirings and the opposite-phase common electrode drive waveforms to the odd and even groups of common electrodes at the same time. A liquid crystal display device characterized by a drive system that writes different video signals to two horizontal lines.