JPH11194366A - Active matrix substrate and its manufacture, liquid crystal device, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which prevents a lateral electric field liquid crystal display device from deteriorating in display owing to variation of an electric field applied to liquid crystal by a pixel electrode and a common electrode due to voltage variation of a signal line. SOLUTION: The active matrix substrate has signal lines 22 and scanning lines 21 arranged crossing each other on a glass substrate 10 and pixel electrodes 23 and common electrodes 24 formed at their intersections in parallel and is provided with pixels where thin film transistors are formed corresponding to the respective pixel electrodes, and a voltage is applied to the pixel electrodes 23 through the thin film transistors to produce an electric field between the pixel electrodes 23 and corresponding common electrodes 24. In this case, the pixel electrodes 23 and common electrodes 24 are formed of the same conductive layer and the signal lines 22 are formed of another conductive layer below the pixel electrodes 23 or common electrodes 24 so that they overlap with each other across an insulating film 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a liquid crystal device of an in-plane switching mode, and more particularly, to a pixel electrode formed by a thin film transistor (hereinafter referred to as a TFT) using a polysilicon layer formed on a substrate as an active layer. The present invention relates to an active matrix substrate used for an active matrix type liquid crystal device for driving a liquid crystal device, a method of manufacturing the same, a liquid crystal device to which the active matrix substrate is applied, and a technique suitable for use in electronic equipment.

[0002]

2. Description of the Related Art A conventional liquid crystal device is a vertical electric field type liquid crystal display device in which liquid crystal is sealed between a pair of parallel substrates each having a transparent electrode, and an electric field in a direction perpendicular to the substrate is applied to the liquid crystal for display. Was common. On the other hand, there has been proposed a lateral electric field type liquid crystal display device in which liquid crystal is sealed between two glass substrates provided with comb electrodes on one substrate and an electric field parallel to the substrates is applied to the liquid crystal to perform display. ing.

The liquid crystal device of the in-plane switching mode has a large viewing angle, and it is not necessary to use a transparent electrode, and the electrode can be formed of a conductive material having excellent conductivity. Therefore, the performance of the device can be improved and the voltage can be reduced. In addition to this, there is an advantage that the manufacturing cost can be reduced because an electrode may be formed only on one of the substrates.

FIG. 13 shows an example of a plane layout and a cross-sectional structure of an active matrix substrate constituting a liquid crystal display device of a horizontal electric field type disclosed in Japanese Patent Application Laid-Open No. Hei 8-171082. Note that FIG. 13B is a cross section taken along line BB ′ in FIG.

In FIG. 13, reference numeral 21 denotes a TF of a pixel in each row.
T is a scanning line for sequentially turning on T, 22 is a signal line arranged in a direction orthogonal to the scanning line 21 to transmit image signals to pixels in each column, 23 is a pixel electrode provided in each pixel, and 24 is a pixel electrode 25, a common electrode arranged to face 23
Is a TFT which is turned on and off by the signal of the scanning line 21 to apply an image signal of the signal line 22 to the pixel electrode 23. These signal lines and electrodes are formed on one of a pair of parallel substrates. Is done.

[0006]

In the conventional in-plane switching type liquid crystal display device, the signal line 22 and the pixel electrode 23 are formed of the same conductive layer as shown in FIG. Reference numeral 24 is formed of another conductive layer below the signal line 22. Therefore, in addition to the original horizontal electric field between the pixel electrode 23 and the common electrode 24 as shown by the solid line a, the signal between the signal line 22 and the pixel electrode 23 as shown by a broken line b generated by the voltage of the signal line 22 There is a problem that the noise electric field is applied to the liquid crystal to deteriorate the display.

That is, a voltage corresponding to the image signal is supplied to the signal line 22, and the voltage on the signal line 22 is transmitted to the corresponding pixel electrode 23 when the TFT 25 is turned on at the timing of selecting the scanning line 21. Since the TFT 25 is controlled so as to maintain the voltage while the TFT is off, when the image signal on the signal line 22 changes in a pixel in which the TFT is off, the voltage between the pixel electrode 23 of the pixel and the signal line 22 changes. The electric field changes, and this is applied to the liquid crystal as an electric field as noise. As a result, the display quality deteriorates.

In the conventional example shown in FIG. 13, since the signal line 22 is provided outside the common electrode 24, a noise electric field between the pixel electrode 23 and the signal line 22 is generated between the pixel electrode 23 and the common electrode 24. However, when the signal line 22 is provided outside the common electrode 24 as described above, the aperture ratio of the pixel is reduced, and another problem that the display becomes dark or the contrast is lowered is obtained. Occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a display from being degraded by an electric field applied to a liquid crystal by a pixel electrode and a common electrode being affected by a change in voltage of a signal line in a horizontal electric field type liquid crystal device. It is to provide the technology that can be.

Another object of the present invention is to provide a technique capable of improving the aperture ratio in a horizontal electric field type liquid crystal device.

Still another object of the present invention is to provide an electronic device such as a liquid crystal panel and a projection type display device capable of performing bright and high-contrast display.

[0012]

According to the present invention, in order to achieve the above object, a plurality of signal lines and scanning lines are arranged on a substrate so as to intersect with each other, and are connected to the signal lines and the scanning lines. A thin film transistor is formed, a pixel electrode is formed connected to the thin film transistor, a common electrode is formed corresponding to the pixel electrode, a pixel is provided, and a voltage is applied to the pixel electrode via the thin film transistor. In an active matrix substrate configured such that an electric field is formed between the pixel electrode and a corresponding common electrode, the pixel electrode and the common electrode are formed of the same conductive layer, and the signal line is connected to the pixel. It is characterized by being formed by another conductive layer so as to overlap with an insulating film below the electrode or the common electrode.

[0013] With such a means, an electric field generated between the signal line and the pixel electrode is generated in the insulating film and does not go outside, so that the electric field applied to the liquid crystal by the pixel electrode and the common electrode is a signal. Changes due to the voltage change of the wire,
It is possible to prevent the displayed image quality from deteriorating.

In addition, since the signal lines are formed so as to overlap in a cross section below the pixel electrode or the common electrode, the aperture ratio of each pixel can be improved.

A plurality of signal lines and scanning lines are provided on a substrate so as to intersect with each other, and a thin film transistor is formed so as to be connected to the signal line and the scanning line. An electrode is formed, a common electrode is formed corresponding to the pixel electrode, and a pixel is provided;
In an active matrix substrate configured such that a voltage is applied to the pixel electrode through the thin film transistor to form an electric field between the pixel electrode and a corresponding common electrode, the pixel electrode and the common electrode are insulated from each other. The signal line is formed on a film, and the signal line is formed of another conductive layer so as to overlap below the pixel electrode or the common electrode with an insulating film interposed therebetween.

With such a configuration, a liquid crystal device having an improved aperture ratio can be obtained as described above.

Further, by using a liquid crystal device using the substrate as a light valve, it is possible to provide an electronic device such as a projection display device capable of displaying a brighter image with a higher contrast than a conventional liquid crystal display device of an in-plane switching method. It can be used. In particular, when a TN type liquid crystal device is used as a light valve, the light valve is arranged to be inclined with respect to the optical axis due to viewing angle characteristics. Therefore, there is a problem that the projected display has a trapezoidal shape. However, by using the liquid crystal device as in the present application as a light valve, the viewing angle characteristics are improved, so that the liquid crystal device is almost perpendicular to the optical axis. Since the liquid crystal device can be arranged, the image obtained by the company is substantially square, which has the effect that it does not become a trapezoidal display as in the past.

Preferably, the signal line has a protruding portion so as to cover a gap between an end of the pixel electrode and the common electrode and a gap between an end of the common electrode and the scanning line. Accordingly, it is possible to prevent the light from leaking from the gap between the electrodes and reduce the contrast without providing a black mask that blocks light.

A plurality of signal lines and scanning lines are provided on a substrate so as to intersect with each other, and a thin film transistor is formed by connecting to the signal line and the scanning line. An electrode is formed, a common electrode is formed corresponding to the pixel electrode, and a pixel is provided;
In the method of manufacturing an active matrix substrate configured to apply a voltage to the pixel electrode via the thin film transistor to form an electric field between the pixel electrode and a corresponding common electrode, forming the signal line A step of forming an insulating film after forming the signal line, and a step of simultaneously forming the pixel electrode and the common electrode after forming the insulating film. With such a manufacturing method, the electric field generated between the signal line and the pixel electrode is generated in the insulating film and does not go outside, so that the electric field applied to the liquid crystal by the pixel electrode and the common electrode is generated by the signal line. It is possible to prevent the display quality from being deteriorated due to the change due to the voltage change.

Further, the pixel electrode is connected to a semiconductor layer (drain region) serving as an operation layer of the thin film transistor via a buffer layer formed of the same conductive layer as the conductive layer forming the signal line. Good. As a result, the diameter of the contact hole can be suppressed from expanding and the aperture ratio can be improved, as compared with a method in which the pixel electrode is directly in contact with the drain region without the buffer layer.

Further, the apparatus comprises a light source, a liquid crystal light valve for modulating and transmitting or reflecting light from the light source, and projection optical means for condensing and modulating and projecting the light modulated by the liquid crystal light valve. Wherein the liquid crystal light valve is formed of a liquid crystal device having at least a pixel electrode on one substrate, a switching element connected to the pixel electrode, and a common electrode. And

With this configuration, it is not necessary to arrange the light valve at an angle to the optical axis, and the projected display screen does not become trapezoidal.

Further, the liquid crystal device of the present invention can be applied to various electronic devices.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a plan layout and a sectional view of a first embodiment of an in-plane switching type active matrix substrate to which the present invention is applied. 1 and 2 show a layout and a cross-sectional structure of one pixel portion among pixels arranged in a matrix. FIG.
2A is a cross section taken along the line AA 'in FIG. 1, and FIG. 2B is a cross section taken along the line BB' in FIG. 1, that is, a cross section taken along a polysilicon layer serving as a TFT operation layer. The structure is shown.

In FIG. 1, reference numeral 11 denotes a polysilicon layer constituting an operation layer of the TFT.
Is a glass substrate 10 as shown in FIG.
A gate insulating film 13 made of a silicon oxide film is formed on a base insulating film 12 formed on the surface of the semiconductor device. Reference numeral 21 denotes a gate line (scanning line) serving as a common gate electrode of TFTs on the same row (horizontal direction in the figure), and 22 denotes a TFT which is disposed in the vertical direction so as to intersect with the gate line 21 and is on the same column. A signal line (source line) for supplying a voltage to be applied to the pixel electrode to a source region (or a drain region).
The signal line 22 is formed of a conductive layer such as a Ta layer, and the signal line 22 is formed of a conductive layer such as aluminum, copper, or an alloy thereof.

Reference numeral 23 denotes a pixel electrode provided in parallel with the signal line 22, and reference numeral 24 denotes a common electrode provided in parallel with a signal line of an adjacent pixel. The pixel electrode 23 and the common electrode 24 are made of aluminum, The common electrode 24 of each pixel is electrically connected to each other by a connecting portion 24A arranged in the gate line direction to form a comb-like shape, while being formed of the same conductive layer made of tungsten, chromium, molybdenum, or the like. For example, a potential called a so-called LC common potential (the center potential of an AC voltage applied to the liquid crystal by the pixel electrode) is commonly applied.

In FIGS. 1 and 2, reference numeral 14 denotes a buffer layer for connecting the pixel electrode 23 to the TFT drain region (or source region) of the polysilicon layer 11, and reference numeral 15a denotes the signal line 3 for the polysilicon layer. Silicon layer 11
A contact hole 15b for contacting the TFT source region of FIG.
Reference numeral 15c denotes a contact hole for bringing the pixel electrode 4 into contact with the buffer layer 14, and reference numerals 16 and 17 denote insulating films such as a silicon oxide film formed by a CVD method or the like. It is desirable to be subjected to a chemical treatment.

In this embodiment, as shown in FIG. 2A, the pixel electrode 23 and the common electrode 24 are formed of the same conductive layer, and the signal line 22 is connected to the pixel electrode 23 or the common electrode. It is formed of another conductive layer so as to overlap below the insulating film 24 with the insulating film 17 therebetween.
According to this embodiment, since the noise electric field generated between the signal line 22 and the pixel electrode 23 is generated in the insulating film 17 and does not go out as shown by the broken line b, the pixel electrode 23 and the common electrode 2
4, the electric field applied to the liquid crystal can be prevented from being affected by a change in the voltage of the signal line 22 and changing the displayed image quality. Further, since the signal line 22 is formed so as to overlap in cross section below the pixel electrode 23 or the common electrode 24, the aperture ratio of each pixel can be improved.

Further, in this embodiment, the common electrode 2
Projection portions 22a and 22b are provided on the signal line 22 so as to cover the gap between the end of the pixel electrode 23 and the gate line 21 and the gap between the end of the pixel electrode 23 and the common electrode 24, respectively. Accordingly, it is not necessary to provide a light-shielding film called a black mask for preventing light leakage at least at a portion corresponding to the pixel region on the counter substrate side, so that cost can be further reduced and alignment accuracy can be improved. There is an advantage that it is easy to assemble because it does not need to be so high.

The arrow R shown in FIG.
And a rubbing direction of an alignment film (not shown) made of polyimide or the like formed above the common electrode 24. By tilting the pixel electrode 23 and the common electrode 24 by .theta. Also, when a voltage is applied between the common electrodes 24 to change the direction of the liquid crystal, the direction of rotation is always the same.

Next, the manufacturing process of the active matrix substrate of the above embodiment will be described with reference to FIGS. 3 and 4 show a cross-sectional structure of one pixel portion among pixels arranged in a matrix on the substrate.

In this embodiment, CV is applied to the surface of the glass substrate.
After a base insulating film made of a silicon oxide film or the like is formed by a method D or the like, an amorphous silicon film is formed on the base insulating film by a low-pressure CVD method or the like, and then subjected to laser annealing to be crystallized to be non-doped. A polysilicon layer is formed. Then, the polysilicon layer is patterned by etching to form an operation layer 11 to be a channel region and a source / drain region of a TFT to be formed later (FIG. 3A).

Next, a gate insulating film made of a silicon oxide film is formed on the polysilicon operation layer 11 by a CVD method or the like using TEOS as a source. Thereafter, after a conductive layer (for example, TaN / Ta) is formed to a predetermined thickness on the gate insulating film, patterning is performed by etching to form a gate electrode / gate line 21 so as to cross the polysilicon operation layer 11. Is formed (FIG. 3B).
Then, an impurity such as phosphorus is implanted into the operation layer 11 by ion implantation to form a source region and a drain region of the TFT (hatched portions in FIG. 2B). At this time, no impurity is introduced into a portion of the operation layer 11 below the gate line 21, and the region remains as a low-concentration channel region.

In the embodiment, a TFT having a source / drain region self-aligned with a gate line will be described. However, the TFT is formed adjacent to a channel region and has a low concentration of a source / drain region. The TFT may be formed as an LDD structure TFT in which a contact region in which impurities are implanted at a high concentration is formed outside the drain region, or a so-called offset structure in which the source / drain region is separated from the end of the gate electrode. Is also good. LDD
With the structure or the offset structure, the leakage current at the time of off can be reduced. The material of the gate line 21 may be Mo, Mo, in addition to TaN / Ta.
A refractory metal such as Ti or W or a metal silicide such as MoSi or WSi may be used.

Next, a phosphorus-free silicate glass film (NS) is formed on the gate line 21 and the gate insulating film.
G film) is formed by a high-pressure CVD method or the like, and contact holes 15a and 15b are formed by dry etching at positions corresponding to the ends of the operation layer 11 of the first insulating film. It is formed (FIG. 3C).

Thereafter, a low-resistance conductive layer such as aluminum, copper, or an alloy thereof is formed on the entire surface by a sputtering method or the like, and then patterned to contact the operating layer 11 (the source region of the TFT) through the contact hole 15a. The buffer layer 14 for connecting the source electrode / signal line 22 and the pixel electrode (to be described later) to the polysilicon operation layer 11 (the drain region of the TFT) is formed (FIG. 3).
(D)). Then, a silicate glass film containing boron and phosphorus (BPSG film) is formed thereon by a low pressure CVD method or the like.
The second insulating film (17) is formed to a desired thickness and flattened.

Next, a contact hole 15c for contacting a pixel electrode is formed in the second insulating film above the buffer layer 14 by anisotropic dry etching (FIG. 4E).
The anisotropic dry etching includes, for example, C
Reactive ion etching using HF3 or SF6 as an etching gas, chemical dry etching, plasma etching, or the like can be considered.

After the formation of the contact hole 15c, a conductive layer such as aluminum, tungsten, chromium or molybdenum is formed on the surface of the second insulating film by sputtering or the like, and is patterned to form a pixel electrode 23 and a common electrode 24. Are simultaneously formed (FIG. 4F). Thereafter, the pixel electrode 23, the common electrode 24 and the second
An alignment film made of polyimide or the like covers about 2
The active matrix substrate is formed to a thickness of about 100 to 1000 angstroms and subjected to rubbing (alignment treatment).

Further, in the active matrix substrate of the above-mentioned embodiment, a color filter layer corresponding to the pixel electrode and a black mask surrounding the periphery thereof are formed on the front side of the active matrix substrate at appropriate intervals. A liquid crystal having positive dielectric anisotropy, for example, is filled in a gap that is arranged and the periphery of which is sealed with a sealing material, thereby forming a liquid crystal panel.

FIGS. 5 to 7 show a second embodiment of the present invention. FIG. 6 shows a cross-sectional structure along the line CC ′ in FIG. This embodiment is almost the same as the first embodiment, except that the pixel electrode 23 formed in the L-shape in the embodiment of FIG. 1 has an inverted L-shape and the embodiment of FIG. The point that the common electrode 24 formed so as to protrude from the upper side to the lower side is formed so as to protrude from the upper side to the lower side.
The point is to connect sc.

Although the storage capacitor in this embodiment is not particularly limited, a part of the pixel electrode 23 is extended along the gate line 21 of the adjacent pixel row, and the pixel electrode 23 and the gate line 21 are connected to each other. Between the electrode layers 18 so as to overlap with them.
And the pixel electrode 23 is connected to the electrode layer 18 via the contact hole 15d, so that the capacitance of the insulating film formed between the electrode layer 18 and the gate line is used as the auxiliary capacitance Csc. . As a result, as shown in an equivalent circuit of FIG. 7, the storage capacitor Csc is connected to the drain of the TFT that transmits the voltage of the signal line 22 to the pixel electrode 23, and the pixel electrode 23 becomes a potential floating when the TFT is turned off. This has the advantage that the accumulated charge is increased and the voltage drop between the pixel electrode and the common electrode due to leakage is suppressed.

Further, in this embodiment, since the electrode layer 18 forming the storage capacitor Csc is formed of the same conductive layer as the conductive layer forming the signal line, the first
The number of process steps does not increase at all, and the aperture ratio does not decrease.

FIG. 8 shows a third embodiment of the present invention. In this embodiment, two pairs of pixel electrodes 23a and 23b are provided for each pixel.
And common electrodes 24a and 24b are provided to form a comb-like electrode, and these are arranged so as to mesh with each other. In a horizontal electric field type liquid crystal display device, if the pitch between each pixel electrode and the common electrode is widened, the intensity of the electric field applied to the liquid crystal becomes low. Therefore, it is necessary to suppress the pitch to a predetermined value or less. In the first to third embodiments, the pitch between each pixel electrode and the common electrode is the same (for example, 10 μm).
In this case, the first and second embodiments have a configuration in which each pixel has a pair of pixel electrodes and a common electrode. Therefore, the pixel pitch is halved compared to the third embodiment. be able to. Therefore, the first and second embodiments are based on VGA (V
ideo Graphics Array) or XGA (Extended Graphics Arr)
Advantageously, it is applied to a high-resolution display device such as ay).

FIG. 9 shows a system configuration example of a substrate on the TFT side of a liquid crystal panel to which the present invention is applied. In the figure,
Numerals 90 denote pixels arranged corresponding to intersections of the gate lines 21 and the signal lines 22 which are arranged so as to cross each other. Each pixel 90 is composed of the pixel electrode 23 and the pixel electrode 23.
A common electrode 24 facing the pixel electrode 24 and a signal line 22
And a TFT 91 for applying a voltage corresponding to the above image signal. The TFTs 91 in the same row have their gates connected to the same gate line 21 and their drains connected to the corresponding pixel electrodes 24. The sources of the TFTs 91 in the same column are connected to the same signal line 22. In this embodiment, the transistors constituting the peripheral circuits (X and Y shift registers and sampling means) 50 and 60 are constituted by so-called polysilicon TFTs having a polysilicon layer as an operation layer, similarly to the TFTs for driving pixels. The transistors constituting the peripheral circuits 50 and 60 are TFs for driving pixels.
It is formed simultaneously with T by the same process.

In this embodiment, a shift register (hereinafter referred to as an X shift register) 51 for sequentially selecting the signal lines 22 is arranged on one side (upper side in the figure) of the display area (pixel matrix). On the other side, a shift register (hereinafter, referred to as a Y shift register) 61 for sequentially selecting and driving the gate lines 21 is provided. A buffer 63 is provided at the next stage of the Y shift register 61 as necessary.

The other end of each signal line 22 is provided with a sampling switch 52 composed of a TFT.
These sampling switches 52 are connected to external terminals 74,
Connected to video lines 54, 55, and 56 for transmitting video signals and data signals input to 75 and 76,
It is configured to be sequentially turned on / off by a sampling pulse output from the X shift register 51. The X shift register 51 sequentially switches all signal lines 22 during one horizontal scanning period based on clocks CLX and / CLK externally input via terminals 72 and 73.
Sampling pulses X1, X2,
X3, ‥‥‥ Xn are formed and a sampling switch 5 is formed.
2 control terminal.

On the other hand, the Y shift register 61 receives a clock CL inputted from the outside via terminals 77 and 78.
It is operated in synchronization with Y and / CLY to sequentially drive each gate line 21.

FIG. 10 shows a configuration example of a liquid crystal panel 30 to which the active matrix substrate is applied. As shown in the figure, on the active matrix substrate (TFT array substrate) 10, a pixel region regulated by a plurality of pixel electrodes 23 (a liquid crystal on which an image is displayed due to a change in the orientation of the liquid crystal layer 37). A seal member 36 made of a photocurable resin is provided along the pixel region as an example of a seal member that surrounds the liquid crystal layer 37 by bonding the two substrates together around the (panel region). Further, a light-shielding peripheral parting layer 35 is provided on a portion of the incident side counter substrate 31 having the color filter layer 33 corresponding to the above-mentioned pixel region outside seal material 36 inside region.

When the active matrix substrate 10 is set in a light-shielding case in which an opening is opened corresponding to an image region later, the peripheral parting layer 35 has an opening in the case due to a manufacturing error or the like. Is formed of a band-like light-shielding material having a width of about 500 μm and 1 mm around the pixel area so as not to be hidden by the edge of the pixel area, that is, for example, to allow about several hundred μm as a deviation from the case of the active matrix substrate 10. You. Such a light-shielding peripheral parting layer 35 is made of, for example, Cr (chrome).
It is formed on the opposing substrate 31 by sputtering, photolithography, and etching using a metal material such as Ni (nickel) and Al (aluminum). Instead of the metal material, the peripheral parting layer 35 may be formed of a material such as resin black in which carbon or Ti (titanium) is dispersed in a photoresist.

A peripheral circuit (scanning line drive circuit) 50 and a pad 70 as an external terminal are provided along the lower side of the pixel region in the region outside the seal member 36, and are provided on both sides of the pixel region (the left and right sides in the figure). A peripheral circuit (signal line driving circuit) 60 is provided along the side. Further, wirings 105 for electrically connecting the peripheral circuits 60 provided on both sides of the pixel region are provided on the upper side of the pixel region. Columns 106 made of a conductive source voltage material for establishing electrical conduction between the active matrix substrate 10 and the counter substrate 31 are provided at the four corners of the seal material 36. The opposite substrate 31 having substantially the same contour as the sealing material 36 is fixed to the active matrix substrate 10 by the sealing material 36.

FIG. 11 shows another configuration example of the liquid crystal panel 30 to which the active matrix substrate is applied. FIG.
In the liquid crystal panel 30 of the first embodiment, a glass substrate 31 on the incident side having a color filter layer 33 is arranged at an appropriate interval on the surface side of the active matrix substrate 10, and the periphery is sealed with a sealing material 36. Liquid crystal 3 in the gap
7 are filled to form a liquid crystal panel 30.
Above the peripheral circuits 50 and 60, for example, the opposing substrate 3
1 is configured to be shielded from light by a black mask or the like. The position where the sealing material is provided is determined so that the pad 70 as an external terminal for inputting a signal from the outside is located outside the sealing material 36.

FIG. 12 shows an example of the configuration of a projection display device as an example of an electronic apparatus in which the liquid crystal device of the above embodiment is applied as a liquid crystal light valve.

FIG. 21 is a schematic configuration diagram showing a main part of the projection display device. In the figure, 10 is a light source, 13 and 14 are dichroic mirrors, 15, 16 and 17 are reflection mirrors, 1
8, 19, and 20 indicate relay lenses, 22, 23, and 24 indicate liquid crystal light valves, 25 indicates a cross dichroic prism, and 26 indicates a projection lens. The light source 10 includes a lamp 11 such as a metal halide and a reflector 1 that reflects light from the lamp.
Consists of two. The dichroic mirror 13 that reflects blue light and green light transmits red light of the white light flux from the light source 10 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 17 and enters the red light liquid crystal light valve 22. On the other hand, green light of the color light reflected by the dichroic mirror 13 is reflected by the dichroic mirror 14 that reflects green light, and is incident on the liquid crystal light valve 23 for green light. On the other hand, the blue light also passes through the second dichroic mirror 14. For blue light, in order to prevent light loss due to a long optical path, a light guide means 21 including a relay lens system including an incident lens 18, a relay lens 19, and an exit lens 20 is provided. The light enters the liquid crystal light valve 24 for light. The three color lights modulated by the respective light valves enter the cross dichroic prism 25. This prism has four right-angle prisms bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface. The three color lights are combined by these dielectric multilayer films to form light representing a color image. The synthesized light is projected on a screen 27 by a projection lens 26 which is a projection optical system,
The image is displayed enlarged.

The present invention is different from a conventional liquid crystal display device using a TN type liquid crystal, in which a horizontal electric field type having a wide viewing angle (so-called I-type) is used.
(PS mode) liquid crystal device. Fig. 1
The results are shown in FIG. (A) is a conventional TN type liquid crystal device,
It has a viewing angle characteristic like a shaded portion. Therefore, in the conventional projection type liquid crystal device, the liquid crystal device is arranged to be inclined with respect to the optical axis in accordance with the viewing angle characteristics of the liquid crystal device used as a light valve. Because of this arrangement, the conventional projection-type liquid crystal device has a problem in that the projected display has a trapezoidal shape, and the displayed width differs between the upper and lower sides of the displayed image, resulting in a distorted display.

On the other hand, by using the liquid crystal device of the present invention as a light valve, such a problem, that is, a problem that a projected image becomes trapezoidal can be solved. That is, FIG. 14B shows the viewing angle characteristics of the in-plane switching type liquid crystal device as shown in the present application, and it can be seen that the viewing angle characteristics are substantially uniform as a whole as shown. Therefore, the liquid crystal device, which is a light valve, can be arranged perpendicularly to the optical axis without being affected by the viewing angle characteristics, and there is no trapezoidal display.

Next, an electronic apparatus constituted by using the liquid crystal device of the above embodiment is provided with a display information output source 10 shown in FIG.
00, display information processing circuit 1002, display drive circuit 100
4, a display panel 1006 such as a liquid crystal panel, a clock generation circuit 1008, and a power supply circuit 1010. The display information output source 1000 includes a memory such as a ROM or a RAM, a tuning circuit that tunes and outputs a television signal, and the like, and outputs display information such as a video signal based on a clock from a clock generation circuit 1008. I do. The display information processing circuit 1002 includes a clock generation circuit 1
The display information is processed and output based on the clock from 008. The display information processing circuit 1002 can include, for example, an amplification / polarity inversion circuit, a phase expansion circuit, a rotation circuit, a gamma correction circuit, a clamp circuit, and the like. The display driving circuit 1004 includes a scanning side driving circuit and a data side driving circuit, and drives the liquid crystal panel 1006 for display. The power supply circuit 1010 supplies power to each of the above circuits.

FIG. 12 shows an electronic apparatus having such a configuration.
, A personal computer (PC) and an engineering workstation (EWS) for multimedia shown in FIG. 16, a pager shown in FIG. 17, or a mobile phone, a word processor, a television, a viewfinder type video or a monitor direct view type video. Examples include a tape recorder, an electronic organizer, an electronic desk calculator, a car navigation device, a POS terminal, and a device having a touch panel.

The personal computer 1 shown in FIG.
Reference numeral 200 denotes a main body 1204 having a keyboard 1202.
And a liquid crystal display screen 1206.

A pager 1300 shown in FIG. 17 includes a liquid crystal display substrate 1304, a light guide 1306 having a backlight 1306a, a circuit board 1308, and first and second shield plates 1310, 13 in a metal frame 1302.
12, two elastic conductors 1314 and 1316, and a film carrier tape 1318. Two elastic conductors 1314 and 1316 and film carrier tape 13
Reference numeral 18 denotes a connection between the liquid crystal display substrate 1304 and the circuit board 1308.

Here, the liquid crystal display substrate 1304 has liquid crystal sealed between two transparent substrates 1304a and 1304b, thereby forming at least a dot matrix type liquid crystal display panel. On one transparent substrate, FIG.
Or a display information processing circuit 1002 in addition to the above. Circuits not mounted on the liquid crystal display substrate 1304 are external circuits of the liquid crystal display substrate, and can be mounted on the circuit substrate 1308 in the case of FIG.

FIG. 17 shows the structure of a pager, and therefore requires a circuit board 1308 in addition to the liquid crystal display substrate 1304. However, this is a case where a liquid crystal display device is used as one component for electronic equipment. When a display driving circuit or the like is mounted on a transparent substrate, the minimum unit of the liquid crystal display device is the liquid crystal display substrate 1304. Alternatively, a structure in which the liquid crystal display substrate 1304 is fixed to a metal frame 1302 serving as a housing can be used as a liquid crystal display device which is one component for electronic devices. Further, in the case of a backlight type, a liquid crystal display substrate 1304 and a light guide 1306 provided with a backlight 1306a can be incorporated in a metal frame 1302 to constitute a liquid crystal display device. Instead of these, as shown in FIG.
Two transparent substrates 130 constituting the liquid crystal display substrate 1304
4a and 1304b, a TCP (Tape Carrier Package) in which an IC chip 1324 is mounted on a polyimide tape 1322 on which a metal conductive film is formed.
e) 1320 can be connected to be used as a liquid crystal display device, which is one component for electronic equipment.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, the present invention is not limited to being applied to the driving of the above-described various liquid crystal panels, but is also applicable to electroluminescence and plasma display devices.

[0064]

As described above, according to the present invention, the electric field generated between the signal line and the pixel electrode is generated in the insulating film and does not go outside, so that the electric field is applied to the liquid crystal by the pixel electrode and the common electrode. There is an effect that it is possible to prevent the electric field from being changed by being affected by the change in the voltage of the signal line and the displayed image quality from being deteriorated.

[Brief description of the drawings]

FIG. 1 is a plan layout view of one pixel portion of a first embodiment of an active matrix substrate to which the present invention is applied.

FIG. 2 is a sectional view showing a section taken along line AA ′ and line BB ′ in FIG. 1;

FIG. 3 is a sectional view showing an example (first half) of a method for manufacturing an active matrix substrate according to the first example in the order of steps;

FIG. 4 is a sectional view showing an example (second half) of the method of manufacturing the active matrix substrate according to the first example in the order of steps;

FIG. 5 is a plan layout diagram of one pixel portion of a second embodiment of the active matrix substrate to which the present invention is applied.

FIG. 6 is a sectional view showing a section taken along line CC ′ in FIG. 5;

FIG. 7 is a circuit diagram showing an equivalent circuit of one pixel unit in the embodiment of FIG.

FIG. 8 is a plan layout diagram of one pixel portion of a third embodiment of the active matrix substrate to which the present invention is applied.

FIG. 9 is a block diagram showing a system configuration example of an active matrix substrate suitable for applying the present invention.

10A and 10B are a cross-sectional view and a plan view illustrating a configuration example of a liquid crystal panel using an active matrix substrate according to the present invention.

11A and 11B are a plan view and a cross-sectional view illustrating another configuration example of a liquid crystal panel using the active matrix substrate according to the present invention.

FIG. 12 is a schematic configuration diagram of a video projector as an example of a projection display device in which an LCD using an active matrix substrate according to an embodiment is applied as a light valve.

13A and 13B are a plan layout view and a cross-sectional view illustrating an example of a conventional substrate for an in-plane switching mode liquid crystal display device.

FIG. 14 shows a viewing angle characteristic (a) of a conventional TN type liquid crystal device,
FIG. 4 is a diagram showing viewing angle characteristics (b) of a liquid crystal display device of a horizontal electric field system.

FIG. 15 is a diagram showing an application example of the present invention.

FIG. 16 is a diagram showing an application example of the present invention.

FIG. 17 is a diagram showing an application example of the present invention.

FIG. 18 is a diagram showing an application example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate (glass substrate) 11 Polysilicon layer (operation layer) 12 Base insulating film 13 Gate electrode 14 Gate insulating film 15a-15c Contact hole 16, 17 Insulating film 18 Auxiliary capacitance electrode layer 21 Scanning line (gate line) 22 Signal line (Source line) 23 Pixel electrode 24 Common electrode 30 Liquid crystal panel 31 Counter substrate 33 Color filter layer 36 Seal material 37 Liquid crystal 50, 60 Peripheral circuit 51 X shift register 52 Sampling switch 54 to 56 Video line 61 Y shift register 70 Pad 72 -78 External terminal 90 pixels 91 pixel driving TFT 370 lamp 373,375,376 dichroic mirror 374,377 reflection mirror 378,379,380 light valve 383 dichroic prism 384 projection lens

Claims (10)

[Claims] 1. A plurality of signal lines and scanning lines are provided on a substrate so as to intersect with each other, and a thin film transistor is formed by being connected to the signal line and the scanning line. An electrode is formed, a common electrode is formed corresponding to the pixel electrode, and a pixel is provided. A voltage is applied to the pixel electrode via the thin film transistor, and an electric field is generated between the pixel electrode and the corresponding common electrode. In the active matrix substrate configured to be formed, the pixel electrode and the common electrode are formed of the same conductive layer, and the signal lines overlap the pixel electrode or the common electrode with an insulating film interposed therebetween. An active matrix substrate formed of another conductive layer. 2. A plurality of signal lines and scanning lines are provided on a substrate so as to intersect with each other, and a thin film transistor is formed by being connected to the signal line and the scanning line. An electrode is formed, a common electrode is formed corresponding to the pixel electrode, and a pixel is provided. A voltage is applied to the pixel electrode via the thin film transistor, and an electric field is generated between the pixel electrode and the corresponding common electrode. In the active matrix substrate configured to be formed, the pixel electrode and the common electrode are formed on the same insulating film, and the signal lines overlap with the insulating film below the pixel electrode or the common electrode with the insulating film interposed therebetween. An active matrix substrate formed of another conductive layer. 3. The signal line is provided with a protruding portion that covers a gap between an end of the pixel electrode and the common electrode and a gap between an end of the common electrode and the scanning line. The active matrix substrate according to claim 1 or 2, wherein 4. The semiconductor device according to claim 1, wherein the pixel electrode is connected to a semiconductor layer serving as an operation layer of the thin film transistor via a buffer layer formed of the same conductive layer as a conductive layer forming the signal line. Item 7. The active matrix substrate according to item 1, 2 or 3. 5. The pixel electrode has an extension extending along the scanning line of an adjacent pixel row, and forms an auxiliary capacitor between the extension and the scanning line of the adjacent pixel row. 5. The active matrix substrate according to claim 1, wherein an electrode layer is formed, and the electrode layer is connected to the pixel electrode. 6. The active matrix substrate according to claim 1, wherein the electrode layer is formed of the same conductive layer as a conductive layer forming the signal line. . 7. A plurality of signal lines and scanning lines are provided on a substrate so as to intersect with each other, and a thin film transistor is formed so as to be connected to the signal line and the scanning line. An electrode is formed, a common electrode is formed corresponding to the pixel electrode, and a pixel is provided. A voltage is applied to the pixel electrode via the thin film transistor, and an electric field is generated between the pixel electrode and the corresponding common electrode. In a method for manufacturing an active matrix substrate configured to be formed, a step of forming the signal line, a step of forming an insulating film after forming the signal line, and forming the pixel electrode and the common electrode after forming the insulating film Forming the active matrix substrate simultaneously. 8. The active matrix substrate according to claim 1, 2, 3, 4, 5 or 6, and a substrate having a color filter layer are arranged at a distance, and the active matrix substrate and the substrate are arranged. Wherein a liquid crystal is sealed in a gap between the liquid crystal device and the liquid crystal device. 9. A light source comprising: a light source; a liquid crystal light valve for modulating and transmitting or reflecting light from the light source; and projection optical means for condensing and modulating and projecting light modulated by the liquid crystal light valve. Projection type display device,
The liquid crystal light valve is formed of a liquid crystal device in which a pixel electrode, a switching element connected to the pixel electrode, and a common electrode are formed at least on one substrate. 10. An electronic apparatus comprising the liquid crystal device.