JP2741886B2 - Liquid crystal display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to an active matrix type liquid crystal display device using a thin film transistor (TFT) and a pixel electrode as components of a pixel. It is related to technology that is effective when applied to

[Conventional technology]

An active matrix type color liquid crystal display device has a liquid crystal display section (liquid crystal display panel) in which a plurality of pixels are arranged in a matrix. Each pixel of the liquid crystal display section has an intersection between two adjacent scanning signal lines (also called gate signal lines or horizontal signal lines) and two adjacent video signal lines (also called drain signal lines or vertical signal lines). It is located in the area. The scanning signal lines extend in the column direction (horizontal direction) and a plurality of scanning signal lines are arranged in the row direction (vertical direction). On the other hand, the video signal lines extend in the row direction crossing the scanning signal lines, and a plurality of video signal lines are arranged in the column direction.

The liquid crystal display unit is a first substrate in which a thin film transistor, a transparent pixel electrode, a protective film of the thin film transistor, and an alignment film for setting the direction of liquid crystal molecules are sequentially provided on a first transparent glass substrate (lower transparent glass substrate). (Lower substrate)
A second substrate (upper substrate) in which a color filter, a protective film for a color filter, a common transparent pixel electrode, and an alignment film are sequentially provided on a second transparent glass substrate (upper transparent glass substrate); Liquid crystal sealed between the alignment films, and a liquid crystal sealing member (sealant) provided along the entire peripheral edge of the first and second substrates except for the liquid crystal inlet. I have.

The liquid crystal display unit separately manufactures the first substrate and the second substrate, and a plurality of small spherical or cylindrical spacer materials between the two substrates so that the alignment films of the two substrates face each other. Are interposed at predetermined intervals by interposing the liquid crystal, liquid crystal is sealed between the two substrates through a liquid crystal sealing opening, and sealed by a sealing material provided on a peripheral edge of the substrate. Note that a backlight is provided on the first substrate side. In this case, the second substrate is on the display screen side. Alternatively, a backlight may be provided on the second substrate side. In this case, the first substrate side is the display screen side.

As described above, the pixel mainly includes a liquid crystal, a transparent pixel electrode and a common transparent pixel electrode disposed with the liquid crystal interposed, a thin film transistor, and a color filter. Each of the transparent pixel electrode, the thin film transistor, and the color filter is provided for each pixel. In addition, one of a source electrode and a drain electrode of the thin film transistor is connected to a transparent pixel electrode, the other electrode is connected to a video signal line, and the gate electrode is connected to a scanning signal line. . The color filter is formed by coloring a dyeing base material formed of a resin material such as an acrylic resin with coloring, and is configured for each pixel at a position facing the pixel and is dyed separately. That is, the color filter is configured in the intersection area between two adjacent scanning signal lines and two adjacent video signal lines, similarly to the pixel.

Further, in order to avoid a problem that the thin film transistor is turned on when light entering from the second transparent glass substrate side is irradiated on the thin film transistor, a second portion corresponding to the traveling signal line, the video signal line, and the thin film transistor is used. A light shielding metal film (black matrix) made of, for example, chromium is provided on the transparent glass substrate. This can prevent light from the second transparent glass substrate from impinging on the thin film transistor, and also allows light from the first transparent glass substrate to be blocked by the light-shielding metal film so that the contour of the pixel becomes clear. Therefore, the contrast of the liquid crystal display can be improved.

As described above, the sealing material for sealing the liquid crystal is provided at the peripheral edges of the first and second transparent glass substrates of the liquid crystal display device as described above. Since the sealing material is made of, for example, an epoxy resin, light is transmitted. When the light of the backlight passes through the seal portion, the light leaks to the display screen side, and there is a problem that the image quality is deteriorated (it becomes difficult to see). Therefore, similarly to the case where the metal film for light shielding (black matrix) is provided on the second transparent glass substrate corresponding to the scanning signal line, the video signal line, and the thin film transistor, even in the place where the sealing material is provided, Since the sealant transmits light, it is necessary to provide a light-shielding film in the seal portion to block light from the backlight.

Two conventional techniques relating to light shielding of the seal portion will be described.

First, in the first conventional example, a color filter provided on a second transparent glass substrate is used as a film for shielding a seal portion from light. As described above, the color filters are provided in three colors of red, green, and blue. However, since the light-shielding metal film has low brightness, a blue filter having a high light-shielding effect is used. That is, when the blue filter is provided on the second transparent glass substrate, the blue filter is also left on the sealing portion (that is, between the peripheral edge of the second transparent glass substrate and the substrate and the sealing material). . Instead of a blue filter, a filter dyed with three color dyes of red, green and blue, a black filter dyed with a black dye, or the like may be used.

In the second conventional example, a light-shielding metal film (black matrix) made of chromium or the like is used as a film for shielding the seal portion from light. That is, when providing a light shielding metal film on the second transparent glass substrate,
A light-shielding metal film is also provided on the seal portion.

[Problems to be solved by the invention]

The first and second conventional examples have the following problems.

First, when a color filter is used as a film for performing light shielding of a seal portion as in the first conventional example,
Since the adhesion between the color filter and the transparent glass substrate is very poor, the first substrate and the second substrate are separated from each other by stress applied from the outside in the manufacturing process or in a reliability test, and the yield and reliability are reduced. There was a problem of bad.

When a light-shielding metal film (black matrix) made of chromium or the like is used as a film for shielding the seal portion as in the second conventional example, the end of the metal film is formed at the end of the substrate. If moisture adheres to the exposed end of the metal film during use of the device, a wiring (pixel electrode) exists near the seal portion, which causes an electrical short circuit (short), Alternatively, electrolysis occurs due to the adhesion of moisture, which causes electrolytic corrosion and disconnection of wiring. Further, if electrolytic corrosion further proceeds, the seal portion is peeled off, which has a problem of poor reliability.

An object of the present invention is to provide a liquid crystal display device that can prevent peeling of a seal portion, short circuit, electrolytic corrosion, and disconnection, and can improve yield and reliability.

[Means for solving the problem]

In order to achieve the above object, the liquid crystal display device of the present invention has a structure in which at least a light-shielding metal film is provided between a sealing material and a transparent glass substrate in contact with the substrate, and an outer end of the metal film The part is covered by at least the color filter.

Note that a protective film may be left on the metal film (that is, between the metal film and the sealant) and on the color filter covering the outer end of the metal film.

FIG. 1A is a schematic cross-sectional view of an essential part showing an example of the configuration of the liquid crystal display device of the present invention, and FIG. 1B is a liquid crystal for explaining an example of the configuration of the liquid crystal display device of the present invention. It is a schematic plan view of a display part.

1 (A) and 1 (B), SUB1 is a first transparent glass substrate, SUB2 is a second transparent glass substrate, FIL is a color filter, R is a red filter, G is an edge color filter, and B is a blue filter. , PSV is a protective film for protecting the color filter, ITO is the pixel electrode, LC is the liquid crystal, SL is the sealing material, MF
Is a light-shielding metal film, E is an outer end of the metal film MF, and SE is a liquid crystal sealing port (FIG. 1 (B)). In this figure,
Parts not directly related to the present invention, for example, an alignment film and the like are not shown.

First transparent glass substrate SUB1 and second transparent glass substrate SU
The liquid crystal LC is sealed between the two substrates at a predetermined interval from the substrate B2, and the liquid crystal LC is provided on a peripheral edge of the both substrates (see FIG. 1 (B)). Sealed by SL, a metal film MF is provided between the sealing material SL and the second transparent glass substrate SUB2 in contact with the substrate, a protective film PSV is provided on the metal film MF, and The outer end E of the film MF is the blue filter B of the color filter FIL and the protective film P.
Covered with SV.

[Action]

In the liquid crystal display device of the present invention, a metal film is provided between the transparent glass substrate and the sealing material so as to be in contact with the transparent glass substrate to shield the sealing portion from light. Since the adhesion between the metal film and the glass substrate is good, peeling of the seal portion (separation between the second transparent glass substrate and the sealant), which has conventionally occurred, can be prevented. Note that it is preferable to use an inorganic metal as a material of the metal film so that the metal film has good adhesion to a glass substrate.

Further, since the outer end of the metal film is covered with the color filter, it is possible to prevent short-circuit, electrolytic corrosion, and disconnection caused by adhesion of moisture to the metal film. In addition,
Considering the case where the outer edge of the metal film is covered with a protective film for a color filter, the protective film is very thin and does not have a sufficient effect of preventing the adverse effect of attached moisture. By covering the end portion, the adverse effect due to the attached moisture can be effectively prevented. As a color filter covering the outer end of the metal film, it is desirable to use a blue filter having the lowest brightness so that the light shielding effect at the end of the seal portion is high. The thickness of the color filter increases in the order of the red filter, the green filter, and the blue filter. This is because the dye molecules are larger in the order of red, border color, and blue. By using the thickest blue filter, the effect of covering and protecting the outer edge of the metal film can be increased. As described above, it is desirable that the color filter covering the outer edge of the metal film has a low brightness in terms of the light shielding effect and a relatively thick color filter in terms of protection of the metal film. Although it is desirable to use a filter of another color, a black filter may be used.

Further, since the metal film as the light-shielding film of the present invention can be provided with a smaller thickness than the color filter as the conventional light-shielding film, the gap between the substrates can be easily controlled.

〔Example〕

FIG. 2 is a plan view of a main part of one pixel of a liquid crystal display portion of an active matrix type color liquid crystal display device to which the present invention is applied, and FIG. 3 is a sectional view taken along the line II-II of FIG. FIG. 4 is a cross-sectional view of a portion and a peripheral portion of the seal portion, and FIG. 4 is a plan view of a main part of a liquid crystal display portion in which a plurality of pixels shown in FIG.

As shown in FIG. 3, in the liquid crystal display device of this embodiment, a light-shielding metal film MF made of, for example, Cr formed by a sputtering method is provided between the sealing material SL and the transparent glass substrate SUB2. The protective film PSV2 is provided thereon, and the outer end of the metal film MF is provided with a color filter.
The FIL is covered with a blue filter B and a protective film PSV2.

As described above, in the liquid crystal display device of the present embodiment, the transparent glass substrate SU2 is provided between the transparent glass substrate SUB2 and the sealing material SL.
A metal film MF in contact with B2 is provided to shield the seal portion from light. Since the adhesion between the metal film and the glass substrate is good, the peeling of the seal portion as conventionally occurred (the second transparent glass substrate SU
Separation between B2 and the sealing material SL) can be prevented.

Further, since the outer end of the metal film MF is covered with the color filter FIL, it is possible to prevent short-circuit, electrolytic corrosion, disconnection, and the like due to adhesion of moisture to the metal film. Note that the protective film PSV2 is very thin and does not have a sufficient effect of preventing the adverse effects of attached moisture, so the thick color filter FIV is used.
By covering the outer end of the metal film MF with L, it is possible to effectively prevent the adverse effect of the attached moisture. In this embodiment, a blue filter B is used as a color filter FIL that covers the outer end of the metal film MF. The thickness of the color filter is red filter R, green filter G, blue filter B
In order. This is because the dye molecules are larger in the order of red, green, and blue. In this embodiment, since the thickest blue filter B is used, the effect of covering and protecting the outer end of the metal film MF is great. Further, since the brightness of the blue filter B is the lowest among the three colors, it is desirable also for the light shielding surface at the end of the seal portion.

Further, the metal film MF as the light-shielding film can be provided with a smaller thickness than the color filter as the conventional light-shielding film, so that the gap between the substrates (the gap between SUB1 and SUB2) can be easily controlled.

As shown in FIG. 3, a thin film transistor TFT and a transparent pixel electrode ITO are provided on the inner surface (liquid crystal side) of the lower transparent glass substrate SUB1. Lower transparent glass substrate S
UB1 has a thickness of, for example, about 1.1 mm.

As shown in FIG. 4, each pixel has two adjacent scanning signal lines (gate signal lines or horizontal signal lines) GL and two adjacent video signal lines (drain signal lines or vertical signal lines) DL. (In a region surrounded by four signal edges). As shown in FIGS. 2 and 4, a plurality of scanning signal lines GL extend in the column direction (horizontal direction) and are arranged in a row direction (vertical direction). The video signal lines DL extend in the row direction and are arranged in a plurality in the column direction.

The thin film transistor TFT of each pixel has 3
It is divided into two (plurality), and is constituted by thin film transistors (divided thin film transistors) TFT1, TFT2 and TFT3.
Each of the thin film transistors TFT1 to TFT3 has substantially the same dimensions (channel length and channel width are the same). Each of the divided thin film transistors TFF1 to TFT3 mainly includes a gate electrode GT, an insulating film GI, and an i-type (intrinsic,
intrinsic, not doped with conductivity determining impurities)
It is composed of an i-type semiconductor layer AS made of silicon (Si), a pair of a source electrode SD1 and a drain electrode SD2. It should be understood that the source and the drain are originally determined by the bias polarity between them, and in the circuit of this liquid crystal display device, the polarity is inverted during the operation, so that the source and the drain are interchanged during the operation. However, also in the following description, for convenience, one SD1 is fixed as a source and the other SD2 is fixed as a drain.

The gate electrode GT protrudes from the scanning signal line GL in the row direction (downward in FIGS. 2 and 5), as shown in detail in FIG. 5 (a plan view of a main part of a pixel in a predetermined manufacturing process). It is configured in a T-shape (branched into a T-shape). That is, the gate electrode GT is configured to extend substantially in parallel with the video signal line DL. The gate electrode GT is configured to protrude to the respective formation regions of the thin film transistors TFT1 to TFT3. The respective gate electrodes GT of the thin film transistors TFT1 to TFT3 are configured integrally (common gate electrode) and are provided continuously on the same scanning signal line GL. The gate electrode GT is
The single-layer first conductive film g1 is formed so that a large step is not formed as much as possible in the formation region of the thin film transistor TFT. The first conductive film g1 is provided with a thickness of about 1100 ° using a chromium (Cr) film provided by, for example, a sputtering method.

As shown in FIG. 2, FIG. 3, and FIG. 6 (a plan view of a main part of a pixel in a predetermined manufacturing process), the gate electrode GT is formed by viewing the i-type semiconductor layer AS (as viewed from below). It is provided larger than that to completely cover. Therefore, when a backlight such as a fluorescent lamp is attached below the lower transparent glass substrate SUB1, the opaque Cr gate electrode GT becomes a shadow, and the semiconductor layer AS is not irradiated with the backlight and the light irradiation described above is performed. Therefore, the conductive phenomenon, that is, the deterioration of the off-characteristics of the TFT is less likely to occur. Note that the original size of the gate electrode GT has a minimum width (including a margin for alignment between the gate electrode and the source / drain electrode) that extends between the source / drain electrodes SD1 and SD2, and a channel width. The depth length that determines W is determined by the ratio to the distance (channel length) L between the source and drain electrodes, that is, the factor W / L that determines the transconductance gm.

The size of the gate electrode in this liquid crystal display device is, of course, larger than the above-mentioned original size.

Considering only the gate electrode GT and the function of light shielding, the gate electrode GT and its wiring GL may be provided integrally in a single layer.
(Al), pure Al, and Al containing palladium (Pd).

Here, the scanning signal line GL is formed of a composite film including the first conductive film g1 and the second conductive film g2 provided thereon. The first conductive film g1 of the scanning signal line GL is provided in the same manufacturing process as the first conductive film g1 of the gate electrode GT, and is integrally formed. The second conductive film g2 is, for example, an Al film formed by a sputtering method and has a thickness of about 900 to 4000 °. The second conductive film g2 is configured so that the resistance value of the scanning signal line GL can be reduced and the signal transmission speed can be increased (the information writing characteristics of the pixel).

The width of the second conductive film g2 of the scanning signal line GL is smaller than the width of the first conductive film g1. In other words, the scanning signal line GL can be formed so that the step shape of the side wall thereof can be made gentle, so that the surface of the insulating film GI provided thereon can be flattened.

The insulating film GI is used as a gate insulating film of each of the thin film transistors TFT1 to TFT3. The insulating film GI is provided above the gate electrode GT and the scanning signal line GL. The insulating film GI is, for example, a silicon nitride film provided by a plasma CVD method and is provided with a thickness of about 3000 °. As described above, the surface of the insulating film GI is flattened in the respective formation regions of the thin film transistors TFT1 to TFT3 and the formation region of the scanning signal line GL.

The i-type semiconductor layer AS is used as a channel forming region of each of the divided thin film transistors TFT1 to TFT3, as shown in detail in FIG. 6 (a plan view of a main part in a predetermined manufacturing process). Each of the i-type semiconductor layers AS of the thin-film transistors TFT1 to TFT3 divided into a plurality is integrally formed in the pixel. That is, each of the plurality of thin-film transistors TFT1 to TFT3 obtained by dividing the pixel includes:
It is composed of one (common) island region of the i-type semiconductor layer As. The i-type semiconductor layer AS is formed of an amorphous silicon film or a polycrystalline silicon film and has a thickness of about 1800 °.

This i-type semiconductor layer AS is made of Si ₃ N
_Following the formation of the insulating film GI consisting of ₄ , the same plasma CVD
In the apparatus, the lower transparent glass substrate SUB1 is provided without being taken out of the apparatus. Further, an N ⁺ type semiconductor layer d0 doped with P for ohmic contact (third layer)
Figure) is also continuously provided with a thickness of about 400 mm. Thereafter, the lower transparent glass substrate SUB1 is taken out of the CVD apparatus, and the N ⁺ -type semiconductor layer d0 and the i-type semiconductor layer AS are removed by photolithography (photo processing) as shown in FIG. 2, FIG. 3, and FIG. It is patterned into independent islands as shown.

As described above, by integrally configuring the respective i-type semiconductor layers AS of the thin film transistors TFT1 to TFT3 divided into a plurality in one pixel, the thin film transistors TFT1 to TFT3
Is a common drain electrode SD2 for the i-type semiconductor layer AS.
(Actually, a step corresponding to a thickness obtained by adding the thickness of the first conductive film g1, the thickness of the N ⁺ -type semiconductor layer d0, and the thickness of the i-type semiconductor layer AS) from the drain electrode SD2 side to i The drain electrode SD2 because it only gets over once to the type semiconductor layer AS side.
Is reduced, and the probability of occurrence of point defects can be reduced. That is, in this liquid crystal display device, the point defect generated in the pixel when the drain electrode SD2 gets over the step of the i-type semiconductor layer AS can be reduced to one third.

Also, although different from the layout of this liquid crystal display device, i
In the case where the video signal line DL directly passes over the semiconductor layer AS and the video signal line DL in the portion over which the video signal line DL passes is configured as the drain electrode SD2, when the video signal line DL (drain electrode SD2) passes over the i-type semiconductor layer AS, It is possible to reduce the probability of occurrence of a line defect due to disconnection. That is, by integrally configuring the respective i-type semiconductor layers AS of the thin film transistors TFT1 to TFT3 divided into a plurality in one pixel,
This is because the video signal line DL (drain electrode SD2) passes over the i-type semiconductor layer AS only once (actually, at the start and end of riding).

As shown in detail in FIG. 2, FIG. 6, and FIG. 7 (a plan view of a main part of a pixel in a predetermined manufacturing process), the i-type semiconductor layer AS intersects the scanning signal line GL and the video signal line DL. Section (crossover section).
The extended i-type semiconductor layer AS is configured to reduce a short circuit between the scanning signal line GL and the video signal line DL at the intersection.

After patterning the first conductive film d1 by photolithography, the same photomask is used or
The N ⁺ type semiconductor layer d0 is removed using the conductive film d1 as a mask.
That is, the N ⁺ -type semiconductor layer remaining on the i-type semiconductor layer AS
As for d0, portions other than the first conductive film d1 are removed by self-alignment (self-alignment). At this time, since the N ⁺ type semiconductor layer d0 is etched so as to completely remove the thickness thereof, i
The type semiconductor layer AS is also slightly etched at its surface, but its degree may be controlled by the etching time.

Then, the second conductive film d2 is formed by sputtering Al.
The thickness is set to be 3000 to 5500 mm (in this liquid crystal display device, about 3500 mm). The Al film has less stress than the Cr film and can be provided with a large thickness, and is configured to reduce the resistance values of the source electrode SD1, the drain electrode SD2, and the video signal line DL. That is, the second conductive film
d2 is configured to increase the operation speed of the thin film transistor TFT and increase the signal transmission speed of the video signal line DL. Therefore, the writing characteristics of the pixel can be improved by the second conductive film d2. Second
The conductive film d2 may be provided by an Al film containing Si, copper (Cu), or Pd as an additive, in addition to the Al film.

After the second conductive film d2 is patterned by the photolithography technique, a transparent conductive film (ITO: Nesa film) provided by a sputtering method with a film thickness of 1000 to 2000 mm (about 1200 mm in this liquid crystal display device). Thereby, a third conductive film d3 is provided. The third conductive film d3 forms the source electrode SD1, the drain electrode SD2, and the video signal line DL, and also forms the transparent pixel electrode ITO.

First conductive film d1 of source electrode SD1 and drain electrode SD2
Is that even if a mask misalignment occurs in the manufacturing process between the first conductive film d1, the second conductive film d2, and the third conductive film d3,
The side where the channel is provided is configured to be larger than the second conductive film d2 and the third conductive film d3 (each of the first conductive film d1 to the third conductive film d3). The channel formation region side may be on the line). Further, each of the first conductive films d1 of the source electrode SD1 and the drain electrode SD2 is configured to define the gate length L of the thin film transistor TFT.

As described above, in the thin film transistors TFT1 to TFT3 divided into a plurality in one pixel, the channel forming region side of the first conductive film d1 of each of the source electrode SD1 and the drain electrode SD2 is connected to the second conductive film d2 and the third conductive film By configuring with a size larger than d3, the gate length L of the thin film transistor TFT can be defined by the size between the first conductive films d1 of the source electrode SD1 and the drain electrode SD2. Since the separation dimension (gate length L) between the first conductive films d1 can be defined by processing accuracy (patterning accuracy), the gate length L of each of the thin film transistors TFT1 to TFT3 can be made uniform.

The source electrode SD1 is connected to the transparent pixel electrode ITO as described above. The source electrode SD1 corresponds to a stepped shape of the i-type semiconductor layer As (the thickness obtained by adding the thickness of the first conductive film g1, the thickness of the N ⁺ -type semiconductor layer d0, and the thickness of the i-type semiconductor layer AS). (Step). Specifically, the source electrode SD1 is connected to a first conductive film d1 provided along the step shape of the i-type semiconductor layer AS and to a transparent pixel electrode ITO above the first conductive film d1. The second conductive film d2 is provided with a smaller dimension on the side of the second conductive film, and the third conductive film d3 is connected to the first conductive film d1 exposed from the second conductive film. The first conductive film d1 of the source electrode SD1 is an N ⁺ type semiconductor layer d0
With good adhesion, and is mainly configured as a barrier layer against diffusion from the second conductive film d2. In the second conductive film d2 of the source electrode SD1, the Cr film of the first conductive film d1 can be provided with a large thickness due to an increase in stress.
Since it is not possible to get over the step shape of AS, it is configured to get over this i-type semiconductor layer AS. That is, by providing the second conductive film d2 thickly, the step coverage (step coverage) is improved. Since the second conductive film d2 can be provided thick, it greatly contributes to a reduction in the resistance value of the source electrode SD1 (the same applies to the drain electrode SD2 and the video signal line DL). Since the third conductive film d3 cannot overcome the stepped shape caused by the i-type semiconductor layer AS of the second conductive film d2, the exposed first conductive film d1 can be reduced by reducing the size of the second conductive film d2. It is configured to be connected to. The first conductive film d1 and the third conductive film d3 not only have good adhesiveness, but also have a small step at the connection between them, so that they can be reliably connected.

Thus, the source electrode SD1 of the thin film transistor TFT
A first conductive film d1 as a barrier layer provided at least along the i-type semiconductor layer AS, and a specific resistance value smaller than the first conductive film d1 which is provided on the first conductive film d1. ,
And a second conductive film d2 having a size smaller than that of the first conductive film d1, and the first conductive film d1 exposed from the second conductive film d2.
By connecting the third conductive film d3, which is a transparent pixel electrode ITO, to the thin film transistor TFT and the transparent pixel electrode ITO, it is possible to surely connect the thin film transistor TFT and the point defect caused by the disconnection. Moreover, the source electrode SD1 is
Since the first conductive film d1 has a barrier effect, the second conductive film d2 (Al film) having a small resistance value can be used, so that the resistance value can be reduced.

The drain electrode SD2 is formed integrally with the video signal line DL, and is provided in the same manufacturing process. Drain electrode
SD2 is formed in an L-shape protruding in the column direction intersecting with the video signal line DL. That is, the drain electrodes SD2 of the thin film transistors TFT1 to TFT3 divided into a plurality in one pixel are connected to the same video signal line DL.

The transparent pixel electrode ITO is provided for each pixel,
One of the pixel electrodes of the liquid crystal display is formed. Transparent pixel electrode
ITO is a thin film transistor T that is divided into multiple parts in one pixel.
It is divided into three transparent pixel electrodes (divided transparent pixel electrodes) ITO1, ITO2, and ITO3 corresponding to each of FT1 to TFT3. The transparent pixel electrode ITO1 is connected to the source electrode SD1 of the thin film transistor TFT1. Transparent pixel electrode ITO2
Is connected to the source electrode SD1 of the thin film transistor TFT2. The transparent pixel electrode ITO3 is connected to the source electrode SD1 of the thin film transistor TFT3.

Each of the transparent pixel electrodes ITO1 to ITO3 has substantially the same size as each of the thin film transistors TFT1 to TFT3. Each of the transparent pixel electrodes ITO1 to ITO3 integrally forms the respective i-type semiconductor layers AS of the thin film transistors TFT1 to TFT3 (the divided thin film transistors TFT are intensively arranged in one place).
Therefore, it is configured in an L-shape.

As described above, a thin film transistor TFT is replaced by a plurality of thin film transistors TFT in one pixel disposed in an intersection area between two adjacent scanning signal lines GL and two adjacent video signal lines DL.
By dividing each of the plurality of divided transparent pixel electrodes ITO1 to ITO3 into each of the plurality of divided thin film transistors TFT1 to TFT3, the divided thin film transistors TFT1 to TFT3 are connected to each of the plurality of divided thin film transistors TFT1 to TFT3 (for example, a thin film transistor TFT1). Only becomes a point defect, and the pixel as a whole is not a point defect (the thin film transistors TFT2 and TFT3 are not point defects), so that the point defect of the entire pixel can be reduced.

In addition, some of the divided point defects of the pixel are smaller than the entire area of the pixel (in the case of this liquid crystal display device,
(One-third the area of a pixel), making it difficult to see the point defect.

Further, the transparent pixel electrodes ITO1 to ITO3 obtained by dividing the above-mentioned pixels.
By having each of substantially the same dimensions,
The area of the point defect in the pixel can be made uniform.

Further, the divided transparent pixel electrodes ITO1-IT
By configuring each of O3 with substantially the same size, each liquid crystal capacitance (Cpix) composed of each of the transparent pixel electrodes ITO1 to ITO3 and the common transparent pixel electrode ITO of the upper transparent glass substrate SUB2, Transparent pixel electrodes ITO1 to IT
The overlap capacitance (Cg) generated by the overlap of the transparent pixel electrodes ITO1 to ITO3 added to each of O3 and the gate electrode GT.
and s) can be made uniform. That is, since each of the transparent pixel electrodes ITO1 to ITO3 can make the liquid crystal capacity and the overlap capacity uniform, the DC component to be applied to the liquid crystal molecules of the liquid crystal LC caused by the overlap capacity is made uniform. When the method of canceling out the direct current component is also adopted, the variation of the direct current component applied to the liquid crystal of each pixel can be reduced.

On the thin film transistor TFT and the transparent pixel electrode ITO,
A protective film PSV1 is provided. The protective film PSV1 is provided mainly to protect the thin film transistor TFT from moisture and the like, and uses a film having high transparency and good moisture resistance. The protective film PSV1, for example, is formed of a silicon oxide film or a silicon nitride film provided by a plasma CVD method, and 5000 to 11000
膜厚 (a film thickness of about 8000 で は in this liquid crystal display device).

On top of the protective film PSV1 on the thin film transistor TFT, an i-type semiconductor layer where external light is used as a channel formation region
A shielding film LS is provided so as not to be incident on the AS.
As shown in FIG. 2, the shielding film LS is formed in a region surrounded by a dotted line. The shielding film LS is provided with, for example, an Al film or a Cr film having a high light shielding property, and is provided to a thickness of about 1000 ° by a sputtering method.

Therefore, the common semiconductor layer of the thin film transistors TFT1 to TFT3
AS is sandwiched between the upper and lower light shielding films LS and the gate electrode GT, so that external natural light or backlight does not hit the i-type semiconductor layer AS. Light shielding film
The LS and the gate electrode GT are larger in size than the semiconductor layer AS and are provided in a shape similar to that of the semiconductor layer AS, and have substantially the same size (the gate electrode GT is a light shielding film so that the boundary line can be seen in the figure).
It is drawn smaller than LS).

In addition, the backlight can be attached to the upper transparent glass substrate SUB2 side, and the lower transparent glass substrate SUB1 can be the observation side (externally exposed side). In this case, the light shielding film LS is used for backlight light, and the gate electrode GT is used for natural light. Works as a light shield.

The thin film transistor TFT is configured such that when a positive bias is applied to the gate electrode GT, the channel resistance between the source and the drain decreases, and when the bias is set to 0, the channel resistance increases. That is, the thin film transistor TFT is configured to be controlled by the bias applied to the gate electrode GT by the voltage applied to the transparent pixel electrode ITO.

The liquid crystal LC is sealed between the lower alignment film ORI1 for setting the orientation of liquid crystal molecules and the upper alignment ORI2 in a space provided between the lower transparent glass substrate SUB1 and the upper transparent glass substrate SUB2. .

The lower alignment film ORI1 is provided above the protective film PSV1 on the lower transparent glass substrate SUB1 side.

On the inner (liquid crystal side) surface of the upper transparent glass substrate SUB2, a color filter FIL, a protective film PSV2, a common transparent pixel electrode (COM) ITO, and an upper alignment film ORI2 are sequentially laminated.

The common transparent pixel electrode ITO is opposed to a transparent pixel electrode ITO provided for each pixel on the lower transparent glass substrate SUB1 side, and is configured integrally with another adjacent common transparent pixel electrode ITO. The common transparent pixel electrode ITO is configured to be applied with a common voltage Vcom. The common voltage Vcom is
Low-level drive voltage Vd min applied to video signal line DL
And a high-level drive voltage Vdmax.

The color filter FIL is configured by coloring a dye on a dyed base material formed of a resin material such as an acrylic resin.
The color filter FIL is configured for each pixel at a position facing the pixel and is dyed separately. That is, the color filter FIL is configured in an intersection area between two adjacent scanning signal lines GL and two adjacent video signal lines DL, similarly to the pixel. Each pixel is divided into a plurality of parts in each predetermined color filter of the color filter FIL.

The color filter FIL can be provided as follows. First, a dyed base material is provided on the surface of the upper transparent glass substrate SUB2, and the dyed base material other than the red filter forming region is removed by photolithography. Thereafter, the dyed base material is dyed with a red dye, fixed, and a red filter R is provided. Next, a green filter G and a blue filter B are sequentially provided by performing a similar process.

Thus, by providing each color filter of the color filter FIL in the intersection area facing each pixel, the scanning signal line GL and the video signal line DL exist between the color filters of the color filter FIL. , It is possible to secure a margin for alignment between each pixel and each color filter of the color filter FIL (enlarge the alignment margin). Further, when each color filter of the color filter FIL is provided, a margin for positioning between different color filters can be secured.

That is, in this liquid crystal display device, a pixel is formed in an intersection area between two adjacent scanning signal lines GL and two adjacent video signal lines DL, and this pixel is divided into a plurality of pixels, and the pixel is opposed to the pixel. By providing each color filter of the color filter FIL at the position where the color filter FIL is provided, the above-described point defect can be reduced, and the alignment margin between each pixel and each color filter can be secured.

The protective film PSV2 is provided to prevent the dye obtained by dyeing the color filter FIL into different colors from leaking into the liquid crystal LC. The protective film PSV2 is formed of, for example, a transparent resin material such as an acrylic resin and an epoxy resin.

In this liquid crystal display device, each layer on the lower transparent glass substrate SUB1 side and each layer on the upper transparent glass substrate SUB2 side are separately provided, and then the lower transparent glass substrate SUB1 and the upper transparent glass substrate SUB2 are stacked. Align, liquid crystal between both
Assembled by enclosing LC.

As shown in FIG. 4, a plurality of pixels of the liquid crystal display section are arranged in the same column direction as the direction in which the scanning signal lines GL extend, and each of the pixels X ₁ , X ₂ , X ₃ , X ₄ ,. Make up each. Each pixel column _{X 1, X 2, X 3} , X 4, ... each pixel of constitute the same in each column of the position of the thin film transistor TFT1~TFT3 and the transparent pixel electrode ITO1～ITO3. That is, each pixel in the pixel rows X ₁ , X ₃ ,.
To TFT3 are arranged on the left side, and the arrangement positions of the transparent pixel electrodes ITO1 to ITO3 are arranged on the right side. Pixel column X _1, X _3, ... of the next stage pixel columns in each row direction X _2, X _4, ... Each of the pixels of the pixel column X _1, X _3, ... video signal lines each pixel of It is composed of pixels arranged in line symmetry with respect to DL. That is, the respective pixels of the pixel columns X ₂ , X ₄ ,.
The position of ITO3 is configured on the left side. And the pixel column
Each of the pixels X ₂ , X ₄ ,... Is arranged (shifted) by a half pixel interval in the column direction with respect to each pixel of the pixel columns X ₁ , X ₃ ,. That is, assuming that each pixel interval of the pixel row X is 1.0 (1.0 pitch), the pixel row X of the next stage has each pixel interval of 1.0, and is arranged in the column direction with respect to the preceding pixel row X.
It is shifted by 0.5 pixel interval (0.5 pitch). The video signal lines DL extending in the row direction between the pixels are provided between the pixel columns X.
It is configured to extend in the column direction for a half pixel interval (0.5 pitch).

Thus, in the liquid crystal display, the thin film transistor TF
A plurality of pixels having the same arrangement position of T and the transparent pixel electrode ITO are arranged in the column direction to form a pixel column X, and the next pixel column X of the pixel column X and the pixels of the previous pixel column X are imaged. Signal line DL
FIG. 8 (a pixel and a color filter are superimposed on each other) by constructing a pixel array that is arranged line-symmetrically to as shown by the fragmentary plan view) in the state, the pixels of a predetermined color filter of the preceding pixel row X is provided (e.g., pixels red filter R of the pixel column X ₃ is provided) and next pixel column pixels to which the same color filter is provided in the X (e.g., pixel provided red filters R pixel column X ₄₎ and
It can be separated by 1.5 pixel intervals (1.5 pitch). That is, the pixels of the preceding pixel row X are configured to be always separated by 1.5 pixel intervals from the pixels of the nearest next pixel row provided with the same color filter.
L constitutes a GRB triangular arrangement. The RGB triangular arrangement structure of the color filter FIL can improve the color mixture of each color, so that the resolution of a color image can be improved.

In addition, since the video signal lines DL extend in the column direction only by half pixel intervals between the pixel columns X, they do not cross adjacent video signal lines DL. Therefore, the routing of the video signal lines DL can be eliminated, and the occupied area can be reduced. In addition, the bypass of the video signal lines DL can be eliminated, and the multilayer wiring structure can be eliminated.

FIG. 9 (equivalent circuit diagram of the liquid crystal display) shows a circuit configuration of the liquid crystal display. XiG, Xi + 1G,... Shown in FIG. 9 are video signals DL connected to the pixels provided with the edge color filters G. XiB, Xi + 1B,... Are video signal lines connected to the pixels where the blue filter B is provided.
DL. Xi + 1R, Xi + 2R,... Are video signal lines DL connected to the pixels provided with the red filter R. These video signal lines DL are selected by a video signal drive circuit.
Yi is a scanning signal line GL for selecting the pixel column X ₁ shown in FIG. 4 and FIG. 8. Similarly, each of Yi + 1, Yi + 2,... Is a scanning signal line GL for selecting each of the pixel columns X ₂ , X ₃ ,.
It is. These scanning signal lines GL are connected to a vertical scanning circuit.

The center part in FIG. 3 shows a cross section of one pixel portion,
The left side shows a cross section of a left edge portion of the lower transparent glass substrate SUB1 and the upper transparent glass substrate SUB2 where the external lead wiring exists. The right side is a transparent glass substrate SUB1 and SU
The cross section of the right edge portion of B2 where there is no external lead-out wiring is shown.

The sealing material SL shown on each of the left and right sides of FIG.
The transparent glass substrates SUB1 and SU are configured to seal the liquid crystal LC, excluding the liquid crystal filling port (not shown).
It is provided along the entire periphery of the edge of B2. Seal material SL
Is formed of, for example, an epoxy resin.

Common transparent pixel electrode ITO on the upper transparent glass substrate SUB2 side
Is connected to an external lead wire provided on the lower transparent glass substrate SUB1 side by a silver paste material SIL in at least one place. This external lead-out wiring is provided in the same manufacturing process as each of the above-described gate electrode GT, source electrode SD1, and drain electrode SD2.

Each layer of the alignment layers ORI1 and ORI2, the transparent pixel electrode ITO, the common transparent pixel electrode ITO, the protective films PSV1 and PSV2, and the insulating film GI is provided inside the sealing material SL. Polarizing plate PO
L is lower transparent glass substrate SUB1, upper transparent glass substrate SUB
2 are provided on the outer surface of each.

FIG. 10 is a cross-sectional view of a main part of a pixel and a peripheral part of a seal part of a liquid crystal display part of another active matrix type color liquid crystal display to which the present invention is applied, and FIG. 11 is a liquid crystal display shown in FIG. Plan view showing one pixel of a liquid crystal display portion of the device,
FIG. 12 is a cross-sectional view taken along the line AA of FIG. 11, and FIG.
13 is a plan view of a main part of a liquid crystal display unit in which a plurality of pixels shown in FIG. 11 are arranged, FIGS. 14 to 16 are plan views of a main part in a predetermined manufacturing process of the pixel shown in FIG. 11, and FIG. FIG. 14 is a plan view of relevant parts in a state where the pixel and the color filter shown in FIG. 13 are superimposed.

In this liquid crystal display device, it is possible to improve the aperture ratio of each pixel of the liquid display unit, reduce the DC component applied to the liquid crystal, reduce point defects in the liquid crystal display unit, and reduce black unevenness. Can be.

As shown in FIG. 10, in the liquid crystal display device of the present embodiment, a light-shielding metal film MF made of, for example, Cr formed by a sputtering method is provided between the sealing material SL and the transparent glass substrate SUB2. The protective film PSV2 is provided thereon, and the outer end of the metal film MF is provided with a color filter.
It is covered with FIL (blue filter B) and protective film PSV2.

As described above, in the liquid crystal display device of the present embodiment, the transparent glass substrate SU2 is disposed between the transparent glass substrate SUB2 and the sealing material SL.
A metal film MF in contact with B2 is provided to shield the seal portion from light. Since the adhesion between the metal film and the transparent glass substrate is good, peeling of the seal portion (separation between the second transparent glass substrate SUB2 and the sealing material SL) which occurs conventionally can be prevented.

Further, since the outer end of the metal film MF is covered with the color filter FIL, it is possible to prevent short-circuit, electrolytic corrosion, disconnection, and the like due to adhesion of moisture to the metal film. Note that the protective film PSV2 is very thin and does not have a sufficient effect of preventing the adverse effect on attached moisture.
By covering the outer end of the metal film MF with, it is possible to effectively prevent the adverse effect of the attached moisture. In this embodiment, a blue filter B is used as a color filter FIL that covers the outer end of the metal film MF. The thickness of the color filter increases in the order of the red filter R, the edge color filter G, and the blue filter B. This is because the dye molecules are larger in the order of red, border color, and blue. In this embodiment, since the thickest blue filter B is used, the effect of covering and protecting the outer end of the metal film MF is great. Blue filter B
Since lightness is the lowest among the three colors, it is also desirable in terms of light shielding at the end of the seal portion.

Further, the metal film MF as the light-shielding film can be provided with a smaller thickness than the color filter as the conventional light-shielding film, so that the gap between the substrates (the gap between SUB1 and SUB2) can be easily controlled.

In this liquid crystal display device, as shown in FIG. 11, an i-type semiconductor layer AS in each pixel of a liquid crystal display portion is formed by a thin film transistor TFT1.
To TFT3. That is, each of the thin film transistors TFT1 to TFT3 divided into a plurality of pixels in one pixel is formed of an independent island region of the i-type semiconductor layer AS.

In addition, each of the transparent pixel electrodes ITO1 to ITO3 connected to each of the thin film transistors TFT1 to TFT3 overlaps the next-stage scanning signal line GL in the row direction on the side opposite to the side connected to the thin film transistors TFT1 to TFT3. Have been. This superimposition constitutes a storage capacitance element (capacitance element) Cadd in which each of the transparent pixel electrodes ITO1 to ITO3 is used as one electrode, and the next-stage scanning signal line GL is used as the other electrode. The dielectric film of the storage capacitor Cadd is formed of the same layer as the insulating film GI used as the gate insulating film of the thin film transistor TFT.

The gate electrode GT is provided larger than the i-type semiconductor layer AS, similarly to the liquid crystal display device shown in FIG. 2 and the like. In this liquid crystal display device, the thin film transistors TFT1 to TFT3 are provided for each independent i-type semiconductor layer AS. Therefore, a large pattern is provided for each thin film transistor TFT.

In addition, since the black matrix pattern BM is provided in a portion corresponding to the scanning signal line GL, the video signal line DL, and the thin film transistor TFT of the upper transparent glass substrate SUB2, the contour of the pixel becomes clear, so that the contrast is improved. In addition, it is possible to prevent external natural light from hitting the thin film transistor TFT.

FIG. 18 shows an equivalent circuit of the pixel shown in FIG. No.
In FIG. 18, Cgs is the thin film transistor T, as described above.
This is an overlap capacitance formed by the gate electrode GT and the source electrode SD1 of the FT. The dielectric film of the overlap capacitance Cgs is the insulating film GI. Cpix is a liquid crystal capacitance formed between the transparent pixel electrode ITO (PIX) and the common transparent pixel electrode ITO (COM). The dielectric films of the liquid crystal capacitor Cpix are the liquid crystal LC, the protective film PSV1, and the alignment films ORI1, ORI2. Vlc is a midpoint potential.

When the thin film transistor TFT switches, the storage capacitance element Cadd functions to reduce the influence of the gate potential change ΔVg on the midpoint potential (pixel electrode potential) Vlc. This situation is represented by the following equation.

ΔVlc = {(Cgs / (Cgs + Cadd + Opix)} × ΔVg Here, ΔVlc represents a change in the midpoint potential due to ΔVg, and this change ΔVlc causes a DC component applied to the liquid crystal. As the capacitance is increased, the value can be decreased, and the storage capacitance element Cadd also has an effect of extending the discharge time, and accumulates video information after the thin film transistor TFT is turned off for a long time.
The reduction of the DC component applied to the liquid crystal LC improves the life of the liquid crystal LC, and can reduce so-called burn-in in which the previous image remains when the liquid crystal display screen is switched.

As described above, since the gate electrode GT is provided so as to completely cover the semiconductor layer AS, the overlapping area with the source / drain electrodes SD1 and SD2 increases, and therefore the parasitic capacitance Cgs increases and the midpoint increases. The potential Vlc has an adverse effect of being easily affected by the gate (scan) signal Vg. However, this disadvantage can be eliminated by providing the storage capacitor Cadd.

Further, in a liquid crystal display device having pixels in the intersection area between two scanning signal lines GL and two video signal lines Dl, one of the two scanning signal lines GL selects one of the two scanning signal lines GL. The thin film transistor TFT of the pixel to be divided into a plurality of TFTs, and the divided thin film transistors TFT1 to TFT3 are connected to ITO1 to ITO3 obtained by dividing the transparent pixel electrode ITO into a plurality, respectively, and the divided transparent pixel electrodes ITO1 to ITO3 are respectively connected. Each of which has the pixel electrode ITO as one electrode and the other scanning signal line GL of the two scanning signal lines GL as a capacitor electrode line to constitute a storage capacitor Cadd as the other electrode. Accordingly, as described above, only a part of the divided pixel becomes a point defect, and the pixel as a whole is not a point defect.Therefore, the point defect of the pixel can be reduced, and the liquid crystal is stored in the storage capacitor Cadd. Join LC Since the DC component can be reduced, the life of the liquid crystal LC can be improved. In particular, by dividing the pixels, it is possible to reduce point defects caused by a short circuit between the gate electrode GT of the thin film transistor TFT and the source electrode SD1 or the drain electrode SD2, and to reduce the storage capacitance with each of the transparent pixel electrodes ITO1 to ITO3. Point defects caused by a short circuit with the other electrode (capacitor electrode line) of the element Cadd can be reduced. The point defect on the latter side is reduced to one third in the case of this liquid crystal display device. As a result, some of the divided point defects of the pixel are:
Since the area is smaller than the entire area of the pixel, the point defect can be made difficult to see.

The storage capacitance of the storage capacitance element Cadd is 4 to 8 times the liquid crystal capacitance Cpix (4 · Cpix <Cadd) due to the writing characteristics of the pixel.
<8 · Cpix), which is set to a value of about 8 to 32 times (8 · Cgs <Cadd <32 · Cgs) the overlapping capacity Cgs.

Further, the scanning signal line GL is formed of a composite film in which the second conductive film (Al film) g2 is superposed on the first conductive film (Cr film) g1, and the other electrode of the storage capacitor element Cadd, that is, the capacitor electrode line By forming the branched portion with a single-layer film made of one of the first conductive films g1 of the composite film, the resistance value of the scanning signal line GL can be reduced, and the writing characteristics can be improved. One electrode (transparent pixel electrode ITO) of the storage capacitor Cadd can be securely adhered to the insulating film GI along a stepped portion based on the other electrode of the storage capacitor Cadd. Disconnection of the electrodes can be reduced.

Further, the other electrode of the storage capacitor Cadd is formed of a single-layer first conductive film g1 and the second conductive film g2 of the Al film is not formed, so that the other electrode of the storage capacitor Cadd due to the hillock of the Al film is formed. A short circuit between the electrode and one of the electrodes can be prevented.

As in the case of the source electrode SD1, a branched portion is formed between each of the transparent pixel electrodes IT1O to ITO3, which are overlapped to form the storage capacitor Cadd, and the branched portion of the capacitor electrode line. Transparent pixel electrode when overcoming the step shape of
An island region composed of the first conductive film d1 and the second conductive film d2 is provided so that the ITO is not disconnected. This island region is configured as small as possible so as not to reduce the area (opening ratio) of the transparent pixel electrode ITO.

As described above, the first conductive film is provided between one electrode of the storage capacitor Cadd and the insulating film GI that can be used as the dielectric film.
d1 and a second conductive film d2 having a smaller specific resistance and a smaller size than the first conductive film d1 provided thereon constitute an underlayer provided with the one electrode (third conductive film). By connecting the film d3) to the first conductive film d1 exposed from the second conductive film d2 of the base layer, one side of the storage capacitor Cadd can be surely formed along a step portion based on the other electrode of the storage capacitor Cadd. Electrodes can be bonded, so the storage capacitor Cadd
Disconnection of one of the electrodes can be reduced.

The liquid crystal display unit of the liquid crystal display device in which the storage capacitor Cadd is provided on the transparent pixel electrode ITO of the pixel is configured as shown in FIG. 20 (an equivalent circuit diagram showing the liquid crystal display unit). The liquid crystal display section is configured by repeating a unit basic pattern including pixels, scanning signal lines GL, and video signal lines DL. The final scanning signal line GL (or the first scanning signal line GL) used as a capacitor electrode line is connected to a common transparent pixel electrode (Vcom) ITO as shown in FIG. Common transparent pixel electrode ITO
As shown in FIG. 3, is connected to an external lead-out wiring by a silver paste material SL at a peripheral portion of the liquid crystal display device. In addition, some of the conductive layers (g1 and g2) of the external lead wiring are formed in the same manufacturing process as the scanning signal line GL. As a result, the final scanning signal line GL (capacitance electrode line)
Can be easily connected to the common transparent pixel electrode ITO.

In this way, by connecting the last stage of the capacitor electrode line to the common transparent pixel electrode (Vcom) ITO of the pixel, the last stage capacitor electrode line can be integrally formed with a part of the conductive layer of the external lead-out line. In addition, since the common transparent pixel electrode ITO is connected to the external lead-out line, the capacitor electrode line of the final stage of the simple configuration can be connected to the common transparent pixel electrode ITO.

The liquid crystal display device is based on a direct current canceling method (a DC canceling method) described in Japanese Patent Application No. 62-95125.
As shown in the figure (time chart), by controlling the driving voltage of the scanning signal line DL, the DC component applied to the liquid crystal LC can be further reduced. In FIG.
Is the drive voltage of an arbitrary scan signal line GL, and Vi + 1 is the drive voltage of the next-stage scan signal line GL. Vee is a low-level driving voltage Vd min applied to the scanning signal line GL, and Vdd is a high-level driving voltage Vd max applied to the scanning signal line GL. The voltage change ΔV _{1 to} ΔV ₄ of the midpoint potential Vlc (see FIG. 18) at each time t = t _{1 to} t ₄ is the total capacitance (Cg) of the pixel.
If s + Cpix + Cadd) is C, the following equation is obtained.

ΔV ₁ = − (Cgs / C) · V2 ΔV ₂ = + (Cgs / C) · (V1 + V2) − (Cadd / C) · V2 ΔV ₃ = − (Cgs / C) · V1 + (Cadd / C) · (V1 + V2) ΔV ₄ = − (Cadd / C) · V1 Here, if the drive voltage applied to the scanning signal line GL is sufficient (see [Note] below), the DC voltage applied to the liquid crystal LC is:
It is expressed by the following equation.

ΔV ₃ + ΔV ₄ = (Cadd · V2−Cgs · V1) / C Therefore, if Cadd · V2 = Cgs · V1, the DC voltage applied to the liquid crystal LC becomes zero.

Note: the time t _1, the variation of the scanning line Vi at t ₂ is affects the mid-point potential Vlc, mid-point potential Vlc during the period t ₂ ~t ₃ signal line X
The potential is set to the same as the video signal potential through i (sufficient writing of the video signal). The potential applied to the liquid crystal LC is almost determined by the potential immediately after the thin film transistor TFT is turned off (the off period of the thin film transistor TFT is much longer than the on period). Therefore, the calculation of the DC component applied to the liquid crystal LC
t _{1 to} t ₃ can be almost neglected, and it is sufficient to consider the potential immediately after the thin film transistor TFT is turned off, that is, the influence of the transition at times t ₃ and t ₄ . Note that the polarity of the video signal Vi is inverted for each frame or for each line, and the DC component due to the video signal itself is set to zero.

That is, in the direct current canceling method, the drop due to the pull-in of the midpoint potential Vlc due to the superposition capacitance Cgs is pushed up by the drive voltage applied to the storage capacitance element Cadd and the next-stage scanning signal line GL (capacitance electrode line), The DC component applied to the LC can be made extremely small. As a result, the liquid crystal display device can improve the life of the liquid crystal LC. Of course, when the gate electrode GT is increased in order to increase the light blocking effect, the storage capacitance of the storage capacitor Cadd may be increased accordingly.

As shown in FIG. 21 (equivalent circuit diagram showing a liquid crystal display unit), this direct current canceling method uses a first stage scanning signal line GL (or capacitance electrode line) and a last stage capacitance electrode line (or scanning signal line G).
L) can be adopted by connecting. No. 2
Although only four scanning signal lines GL are shown in FIG. 1 for convenience, about several hundred scanning signal lines GL are actually arranged. The connection between the first-stage scanning signal line GL and the last-stage capacitor electrode line is performed by an internal wiring or an external lead-out wiring in the liquid crystal display unit.

As described above, the liquid crystal display device connects the first-stage scanning signal line GL to the last-stage capacitance electrode line, thereby forming the scanning signal line GL.
All GL and capacitance electrode lines can be connected to the vertical scanning circuit, so DC cancellation method (DC cancellation method)
Can be adopted. As a result, the DC component applied to the liquid crystal LC can be reduced, so that the life of the liquid crystal LC can be improved.

As described above, the present invention has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and it is needless to say that various changes can be made without departing from the gist of the present invention.

For example, the protective film PSV on the light shielding metal film MF or on the color filter covering the outer end of the metal film MF may be deleted. In the above embodiment, the blue filter B is used to cover the outer end of the metal film M4, but a filter of another color, a black filter, or the like may be used. Further, the liquid crystal display device of the present invention is effective in both cases where the backlight is provided on the first transparent glass substrate side or the second transparent glass substrate side.

Further, the present invention can be applied to a liquid crystal display device in which each pixel of the liquid crystal display section is divided into two or four. However, if the number of pixel divisions increases, the aperture ratio decreases. Therefore, as described above, about two to four divisions are appropriate.
Further, the light-shielding effect can be obtained without dividing the pixel. Further, in the above-described embodiment, the inverted staggered structure of the gate electrode shape → gate insulating film formation → semiconductor formation → source / drain electrode formation is described. It is.

〔The invention's effect〕

As described above, in the liquid crystal display device of the present invention, since the metal film having good adhesion to the transparent glass substrate is used for shielding the seal portion from light, the seal portion is peeled off as in the related art (the second case). Separation between the transparent glass substrate and the sealing material) can be prevented. Further, since the outer end of the metal film is covered with the color filter, it is possible to prevent short-circuit, electrolytic corrosion, disconnection, and the like due to adhesion of moisture to the metal film. Since the outer edge of the metal film is covered with a thick color filter, these adverse effects due to the adhesion of moisture can be effectively prevented. Further, since the metal film as the light-shielding film of the present invention can be provided with a smaller thickness than the color filter as the conventional light-shielding film, there is an effect that the gap between the substrates can be easily controlled. Therefore, according to the present invention, it is possible to improve product reliability and yield.

[Brief description of the drawings]

FIG. 1A is a schematic cross-sectional view of an essential part showing an example of the configuration of the liquid crystal display device of the present invention, and FIG. 1B is a liquid crystal for explaining an example of the configuration of the liquid crystal display device of the present invention. FIG. 2 is a schematic plan view of a display portion, FIG. 2 is a plan view of a main portion showing one pixel of a liquid crystal display portion of an active matrix type color liquid crystal display device to which the present invention is applied, and FIG. FIG. 4 is a cross-sectional view of a portion cut along the II-II cutting line and a peripheral portion of the seal portion.
FIG. 5 is a plan view of a main part of a liquid crystal display unit in which a plurality of pixels shown in FIG. 2 are arranged, FIGS. 5 to 7 are plan views of main parts in a predetermined manufacturing process of the pixel shown in FIG. 2, and FIG. FIG. 9 is a plan view of a main part in a state where the pixel and the color filter shown in FIG. 4 are superimposed. FIG. 9 is an equivalent circuit diagram showing a liquid crystal display unit of the active matrix type color liquid crystal display device.
FIG. 10 is a cross-sectional view of a main part of a pixel of a liquid crystal display portion and a peripheral portion of a seal portion of another active matrix type color liquid crystal display device to which the present invention is applied, and FIG. FIG. 12 is a plan view showing one pixel of a liquid crystal display portion of the liquid crystal display device, FIG. 12 is a cross-sectional view taken along a line AA in FIG. 11, and FIG. FIG. 14 is a plan view of a main part of a plurality of liquid crystal display units, FIGS. 14 to 16 are plan views of a main part in a predetermined manufacturing process of the pixel shown in FIG. 11, and FIG.
FIG. 18 is a plan view of a main part in a state where the pixel and the color filter shown in FIG. 13 are superimposed, FIG. 18 is an equivalent circuit diagram of the pixel described in FIG. 11, and FIG. Time chart showing the drive voltage of the line, FIG. 20, FIG.
The figure is an equivalent circuit diagram showing a liquid crystal display section of the active matrix type color liquid crystal display device shown in FIG. SUB1 First transparent glass substrate SUB2 Second transparent glass substrate SL Sealing material FIL Color filter B Blue filter MF Shielding metal film E Outer end of metal film PSV ... Protective film ITO ... Pixel electrode LC ... Liquid crystal SE ... Liquid crystal filling port

Claims (1)

(57) [Claims] A first transparent glass substrate; a first pixel electrode provided on the first transparent glass substrate; a second transparent glass substrate; and a second transparent glass substrate provided on the second transparent glass substrate. Color filter, a protective film provided on the color filter, and a second pixel electrode provided on the protective film, the first transparent glass substrate and the second transparent glass It is overlapped with the substrate at a predetermined interval,
A liquid crystal is sealed between the two substrates, and the liquid crystal is sealed by a sealing material provided on an edge around the two substrates,
At least a light-shielding metal film is provided between the sealing material and the second transparent glass substrate in contact with the substrate, and an outer end of the metal film is covered by at least the color filter. A liquid crystal display device characterized by the above-mentioned.