JPH07333654A - Active matrix type liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent a liq. crystal included in dummy pixels from being impressed with DC component. CONSTITUTION:This active type liq. crystal display device has a panel structure provided with a driving substrate, a counter substrate and liq. crystal held between them, an effective display part 1 visible from an outside when it is seen planarily and a circumferential non-effective display part 2 masked from the outside. The driving substrate is provided with gate lines X of row shapes and signal lines Y of column shapes over the effective display part 1 and the non-effective display part 2 and defines pixel area at each intersecting part between them. A pixel electrode and a thin film transistor Tr driving the pixel is formed in an individual pixel area belonging to the effective display part 1 to constitute a real pixel 3 contributing to a display. Besides, a thin film transistor Tr is formed in a state where a pixel electrode is lacked in an individual pixel area belonging to the non-effective display part 2 to constitute a dummy pixel 5 which does not contribute to the display.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device. More specifically, it relates to the structure of dummy pixels provided in addition to the actual pixels that contribute to display.

[0002]

2. Description of the Related Art The structure of a conventional active matrix type liquid crystal display device will be briefly described with reference to FIG. This type of display device has a panel structure including a drive substrate, a counter substrate, and liquid crystal held between the two. The panel structure has a central effective display portion 101 which is visible from the outside when viewed in plan.
And a peripheral ineffective display portion 102 that is shielded from the outside. In the figure, the effective display portion 101 is thinly shaded for easy understanding. The drive substrate has row-shaped gate lines X and column-shaped signal lines Y extending over both the effective display portion 101 and the ineffective display portion 102, and defines a pixel region at each intersection of both. In the figure,
The effective display area 101 includes 9 pixel areas, and the ineffective display area 102 includes 16 pixel areas. A pixel electrode and an active element for driving the pixel electrode are formed in each pixel region belonging to the effective display portion 101 to form an actual pixel 103 that contributes to display. In this example, the active element is a thin film transistor Tr. A minute liquid crystal cell LC is provided between the pixel electrode and the counter electrode 104 formed on the counter substrate side. A storage capacitor Cs is also formed in parallel with the liquid crystal cell LC.

Similarly, a pixel electrode and an active element are formed in each pixel region belonging to the ineffective display section 102 to form a dummy pixel 105 which does not contribute to display. As shown,
The dummy pixel 105 has the same configuration as the actual pixel 103, and includes a thin film transistor Tr, a liquid crystal cell LC, and a storage capacitor Cs. As can be understood from the above description, the total number of pixels and the number of effective pixels (the number of actual pixels) are generally different in an active matrix liquid crystal display device. That is, there are pixels that are not displayed around the effective display portion and are called dummy pixels as described above. The role of the dummy pixel is first to take measures against damage. In the active matrix type liquid crystal display device, an active element such as a thin film transistor is provided in each pixel region, and opening / closing of the active element is controlled to drive a liquid crystal cell. That is, since there are actually active elements such as thin film transistors as many as hundreds of thousands to millions of pixels, it is extremely difficult in process to create a liquid crystal display device having no defective pixels. is there. Causes of defective pixels include thin film transistor failure due to static electricity, process damage or noise,
In particular, defects frequently occur in the peripheral portion of the panel structure. Therefore, measures have been taken to provide dummy pixels around the effective display area to absorb electrostatic stress from the outside and not to create defective pixels inside.

Dummy pixels are also used as a measure for improving image quality. The signal line may be subjected to coupling due to charging / discharging of the thin film transistor, causing potential fluctuation. Since this potential fluctuation is not uniform during one horizontal period, the image quality deteriorates. For example, in the method of sequentially shifting while selecting a plurality of signal lines at the same time, a band-shaped defect occurs at the end portion of the screen in the horizontal scanning direction. This band-shaped defect is caused by the fact that the overlapping of sampling pulses is canceled on the terminal side of horizontal scanning and the driving condition is different from that of other normal parts. Therefore, in order to equalize the potential fluctuation of the signal line due to the charge / discharge current of the thin film transistor, several dummy pixels are further driven at the end portion in the horizontal scanning direction to improve the image quality.

[0005]

As shown in FIG. 9, a real pixel 103 is integratedly formed in a central effective display portion 101, and a dummy pixel 105 is formed in a peripheral non-effective display portion 102.
Are formed in an integrated manner. Conventionally, the real pixel 103 and the dummy pixel 105 have the same configuration and include an active element and a pixel electrode. The dummy pixels 105 included in the ineffective display portion 102 are shielded from the outside by a black mask or the like. The electrostatic damage and the like applied from the outside are all absorbed by the peripheral dummy pixels 105, and the actual pixels 103 inside
To prevent the breakdown. However, the ineffective display unit 1
In the defective pixel 106 generated in 02, the pixel potential becomes unstable, and the DC component is applied to the liquid crystal cell. This often damages the liquid crystal. When a DC component or the like is continuously applied to the liquid crystal, the damaged portion 107 expands beyond the area of the defective pixel 106 to the periphery and the effective display portion 10 is displayed.
1 may be invaded and the image quality is impaired.

Another problem to be solved will be described with reference to FIG. As described above, the dummy pixel is also used to suppress the band-shaped defect due to the potential fluctuation of the signal line, and an example thereof is shown in FIG. That is, the left non-effective display section 202 and the right non-effective display section 203 are provided at both ends of the central effective display section 201, and dummy pixels are arranged respectively. In this example, the liquid crystal display device has a configuration capable of left-right inverted display, and since horizontal scanning is performed bidirectionally,
The non-effective display portions 202 and 2 are provided on both sides of the central effective display portion 201.
03 is provided. As shown in the figure, in the normal display, horizontal scanning is performed from the left side to the right side, and the actual operation range includes the central effective display section 201 to the right ineffective display section 203. Since the dummy pixel is located at the end portion of the left horizontal scanning, the band-shaped defect, which has been a problem in the past, can be removed. However, the left non-effective display section 202 is excluded from the operation range, so that the pixel potential becomes unstable. As a result, the orientation of the liquid crystal is disturbed, and the damaged portion 204 expands to the periphery and enters the central effective display portion 201.

FIG. 11 shows a case in which left-right reversal display is performed contrary to FIG. At this time, horizontal scanning is performed from the right side to the left side, the operation range includes the central effective display section 201 and the left ineffective display section 202, and the right ineffective display section 203 is excluded from the operation range. Therefore, the dummy pixels included in the right non-effective display section 203 are also in an unstable state, the alignment of the liquid crystal is disturbed, and the damage section 204 enters the central effective display section 201 to deteriorate the image quality.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to prevent damage to the liquid crystal due to a failure of a dummy pixel or a temporary stop of operation. The following measures have been taken in order to achieve this object.
That is, the active matrix type liquid crystal display device according to the present invention has, as a basic configuration, a panel structure including a driving substrate, a counter substrate, and liquid crystal held between the two, and an effective display visible from the outside. And a peripheral non-effective display portion shielded from the outside. The driving substrate includes row-shaped gate lines and column-shaped signal lines extending over both the effective display portion and the non-effective display portion, and defines pixel regions at respective intersections of the both. As a feature of the present invention, a pixel electrode and an active element for driving the pixel electrode are formed in each pixel region belonging to the effective display portion to form an actual pixel that contributes to display,
In each pixel region belonging to the non-effective display portion, an active element is formed in a state of lacking a pixel electrode to form a dummy pixel that does not contribute to display.

In the materialized invention, the active element comprises a thin film transistor having a gate electrode, a source electrode and a drain electrode. In the active element incorporated in the actual pixel, the gate electrode is connected to the gate line, the source electrode is connected to the signal line, and the drain electrode is connected to the pixel electrode. On the other hand, in the active element incorporated in the dummy pixel, the gate electrode is connected to the gate line, the source electrode is connected to the signal line, and the drain electrode is in an open state. Preferably, the non-effective display portion is provided in four directions, vertically and horizontally, so as to surround the effective display portion located at the center. The dummy pixel provided in the non-effective display section has a function of protecting at least an internal real pixel from an external electrostatic stress. Alternatively, the non-effective display section is provided at least on both left and right sides of the effective display section. The dummy pixel provided in the non-effective display section has a function of preventing at least nonuniform operation of the actual pixel.

[0010]

According to the present invention, the pixel electrode and the active element for driving the pixel electrode are formed in the actual pixel, while only the active element is formed in the dummy pixel without the pixel electrode. Since the dummy pixel contains an active element, it is possible to absorb electrostatic stress applied from the outside, and instead of itself breaking down, electrostatic breakdown of the active element incorporated in the actual pixel inside is prevented beforehand. it can. Further, since it can be driven like an actual pixel, it can contribute to making the operating conditions of the actual pixel uniform when it is located at the end portion in the horizontal scanning direction. That is, it functions as a load equivalent to a real pixel. However, while the active element is provided, the pixel electrode is lacking. Therefore, when the active element of the dummy pixel fails due to electrostatic damage or the like, there is no fear that the DC component or the like is applied to the liquid crystal, and the image quality is not disturbed. Further, even if the dummy pixel is placed in an operation stop state due to driving conditions or the like, since the pixel electrode is lacking, the DC component or the like is not applied to the liquid crystal, and there is no fear of impairing the image quality.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic plan view showing a first embodiment of an active matrix type liquid crystal display device according to the present invention. The display device has a panel structure including a drive substrate, a counter substrate, and liquid crystal held between the drive substrate and the counter substrate. It has a non-effective display portion 2 in the periphery. The drive substrate has row-shaped gate lines X and column-shaped signal lines Y extending over both the effective display portion 1 and the ineffective display portion 2, and defines a pixel region at each intersection thereof. In this schematic example, the effective display area 1 includes 9 pixel areas, and is shaded to distinguish it from the 16 pixel areas included in the ineffective display area 2.

A pixel electrode and an active element for driving the pixel electrode are formed in each pixel region belonging to the effective display portion 1 to form an actual pixel 3 that contributes to display. In this example, the active element is a thin film transistor Tr having a gate electrode, a source electrode and a drain electrode. The pixel electrode holds liquid crystal between itself and the counter electrode 4 formed on the counter substrate to form a minute liquid crystal cell LC. In addition, in this example, a storage capacitor Cs is also formed in parallel with the liquid crystal cell LC. The thin film transistor Tr has a gate electrode connected to the gate line X, a source electrode connected to the signal line Y, and a drain electrode connected to the pixel electrode. The drain electrode is further connected to one electrode of the storage capacitor Cs. The other electrode of the storage capacitor Cs is connected to, for example, an auxiliary line held at the same potential as the counter electrode 4. On the equivalent circuit shown, the counter electrode 4 and the auxiliary line are schematically represented by the same line. However, the present invention is not limited to this, and the other electrode of the storage capacitor Cs may be connected to a dedicated auxiliary line or a preceding gate line.

On the other hand, active elements are formed in the individual pixel regions belonging to the ineffective display section 2 in the state where the pixel electrodes are lacking,
The dummy pixel 5 that does not contribute to the display is formed. Specifically, it has the same configuration as the actual pixel except for the pixel electrode, and includes a thin film transistor Tr and a storage capacitor Cs. This is different from the actual pixel 3 in that a minute liquid crystal cell LC does not exist because it lacks a pixel electrode. However, the thin film transistor Tr incorporated in the dummy pixel 5 is the thin film transistor T incorporated in the actual pixel 3.
It is driven in the same way as r. That is, the gate electrode of the thin film transistor Tr of the dummy pixel is connected to the gate line X,
The source electrode is connected to the signal line Y, and only the drain electrode is open.

In this embodiment, the non-effective display portion 2 is provided in four directions in the vertical and horizontal directions so as to surround the effective display portion 1 located at the center, and the dummy pixels 5 are arranged so that at least the internal real pixels 3 are prevented from external electrostatic stress. Has a function to protect.

FIG. 2 shows a schematic sectional structure of one real pixel 3. As shown in the figure, it has a panel structure in which a liquid crystal 8 is held between a lower drive substrate 6 and an upper counter substrate 7. The counter electrode 4 is entirely formed on the inner surface of the counter substrate 7. On the other hand, a thin film transistor Tr and a storage capacitor Cs are formed on the inner surface of the drive substrate 6. The thin film transistor Tr has a semiconductor thin film 9 made of polycrystalline silicon or the like as an element region, on which the gate insulating film 1 is formed.
The gate electrode G is formed in a predetermined shape by patterning 0. The gate electrode G is connected to the gate line X (not shown). Further, an additional electrode 11 is also formed on the semiconductor thin film 9 via the gate insulating film 10 to form the storage capacitor Cs described above. The additional electrode 11 is connected to an auxiliary line (not shown). The thin film transistor Tr and the storage capacitor Cs having such a configuration
Are covered with the first interlayer insulating film 12. A signal line Y is patterned on the source line S of the thin film transistor Tr through a contact hole.
Connected to. The surface of the signal line Y is covered with the second interlayer insulating film 13, and the pixel electrode 14 is pattern-formed thereon. The pixel electrode 14 is made of a transparent conductive film such as ITO and is electrically connected to the drain region D of the thin film transistor Tr through a contact hole. Pixel electrode 14
The above-mentioned fine liquid crystal cell LC is formed by the liquid crystal 8 held between the counter electrode 4 and the counter electrode 4.

FIG. 3 is a waveform diagram for explaining the operation of the active matrix type liquid crystal display device shown in FIG. This display device employs field inversion drive. That is, the polarity of the video signal supplied from the outside is inverted every field (1F), and the potential of the signal line sampled from this is also inverted every 1F with the counter electrode potential Vcom as the center. . In synchronization with this, the gate line Y
, A gate pulse is applied every 1 F to open / close the thin film transistor Tr which is an active element, and the video signal sampled and held in the signal line is written in the pixel electrode. Therefore, the potential applied to the liquid crystal cell of the actual pixel (hereinafter referred to as the pixel potential) is Vc as long as the active element operates normally.
The polarity switches every 1F centering on om. However, when an abnormality such as a failure of the active element occurs, the pixel potential becomes V
The level becomes biased with respect to com, the DC component is continuously applied to the liquid crystal, and damage such as alignment disorder occurs.

In view of this point, in the present invention, the dummy pixel 5 is arranged so as to surround the actual pixel 3 as shown in FIG. 1, and the active element included in the internal actual pixel is caused by electrostatic stress from the outside or the like. Prevents breakdown and destruction. However, the dummy pixel has a high probability of failure due to electrostatic stress, and in the conventional configuration, the DC component is applied through the pixel electrode, and if the liquid crystal damage is diffused, it may enter the effective display portion. There is In view of this point, in the present invention, the configuration of the dummy pixel is different from that of the actual pixel.
The cross-sectional structure is schematically shown in FIG. Portions corresponding to the sectional structure of the actual pixel shown in FIG. 2 are given corresponding reference numerals to facilitate understanding. The only difference is the lack of pixel electrodes. In connection with this, the thin film transistor Tr
The contact hole communicating with the drain region D of is not opened. In other respects, like the actual pixel, the thin film transistor Tr which becomes an active element and the storage capacitor C which becomes its load
s, and has the same driving capability in terms of equivalent circuit. Therefore, even when the pixel electrode is lacking, it has a driving capability equivalent to that of an actual pixel and can sufficiently fulfill the role of a dummy pixel. When the active matrix type liquid crystal display device includes a peripheral circuit section such as a horizontal scanning circuit or a vertical scanning circuit, the configuration of the dummy pixel is the same as that of the peripheral circuit section and does not adversely affect the liquid crystal. If the thin film transistor T is exposed to external stress or noise.
Even if r fails, the liquid crystal 8
There is no fear that a DC component will be applied to.

FIG. 5 is a block diagram showing a second embodiment of the active matrix type liquid crystal display device according to the present invention. As shown in the figure, the display device includes a plurality of gate lines X arranged in rows and a plurality of signal lines Y arranged in columns. Pixel regions are defined in a matrix at the intersections of the two. These pixel areas are located in the central effective display area 2
It is divided into 1 and non-effective display portions on the left and right sides thereof.
In each pixel area belonging to the effective display portion 21, the actual pixel 22
Is provided. The actual pixel 22 is a thin film transistor Tr
And a fine liquid crystal cell LC and a storage capacitor Cs.
It has the same configuration as the actual pixel shown in FIG. That is, the source electrode of the thin film transistor Tr is connected to the corresponding signal line Y, the gate electrode is connected to the corresponding gate line X, and the drain electrode is connected to the pixel electrode located at one end of the liquid crystal cell LC.

A vertical scanning circuit 23 and a horizontal scanning circuit 24 are provided around the effective display area 21 described above. The vertical scanning circuit 23 sequentially vertically scans each gate line X to make the above-mentioned thin film transistor Tr conductive, and selects pixels for one row every horizontal period. On the other hand, the horizontal scanning circuit 24 sequentially scans each signal line Y within one horizontal period to scan the video signal Vs.
ig is sampled, and the video signal Vsig is written in the selected one row of pixels in a dot-sequential manner. Specifically, each signal line Y is connected to the video line 25 via the horizontal switch HSW and supplied with the video signal Vsig.
The horizontal scanning circuit 24 sequentially outputs the sampling pulse φ and its inversion pulse to open / close the individual horizontal switches HSW to sample the liquid crystal signal Vsig described above. Video signal Vs sampled on each signal line Y
ig is written in the pixels for one row through the thin film transistor Tr in the ON state. Then the thin film transistor T
The r is turned off and the written video signal Vsig is held until the next frame. In the present embodiment, the horizontal scanning circuit 24 is a bidirectional type, and it is possible to switch between forward scanning from the left side to the right side of the screen and reverse scanning from the right side to the left side of the screen, and perform a left-right inverted display. I can do things. Note that FIG. 5 shows the state of forward horizontal scanning.

As a feature of the present invention, the signal lines are real signal lines Y1, Y2, ..., Arranged on the effective display section 21.
It is divided into YL and dummy signal lines YD1, YD2, YD3, YD4 arranged on the ineffective display section on the right side. In addition, four dummy signal lines YD are arranged in the non-effective display section located on the left side of the effective display section 21.
These dummy signal lines intersect the left and right end sides of the gate line X. In this embodiment, the liquid crystal cell LC is removed from the individual pixel regions belonging to the left and right ineffective display portions, and the dummy pixel 26 is formed. This dummy pixel 26
The configuration is the same as that of the dummy pixel shown in FIG. In order to make the driving conditions the same as those of the actual pixel 22, the thin film transistor Tr
While the storage capacitor Cs is left, the pixel electrode is removed to prevent the application of the DC component to the liquid crystal. The horizontal scanning circuit 24 described above scans not only actual signal lines but also dummy signal lines. However, in the illustrated forward horizontal scanning, only the central effective display portion 21 and the right non-effective display portion are driven, and the left non-effective display portion is temporarily stopped. That is, the horizontal scanning circuit 24 uses the actual signal line Y
1, Y2, ..., YL are horizontally scanned at a plurality of lines (four lines in this example) at overlapping sampling timings. Dummy signal line YD
Horizontal scanning is added to 1, YD2, YD3, and YD4 at the same overlapping sampling timing. In this case, the dummy signal lines are arranged at least by the number of lines that are simultaneously horizontally scanned at overlapping sampling timings. That is, in this embodiment, at least four dummy signal lines are provided on each side.
More specifically, the horizontal scanning circuit 24 outputs sampling pulses φ ₁ , φ ₂ , to the horizontal switches HSW connected to the actual signal lines Y1, Y2, ..., YL.
…, Φ _L and its inversion pulse are sequentially output. Further, successively, dummy signal lines YD1, YD2, YD3, YD
Sampling pulses φ _D1 , φ _D2 , φ _D3 , and φ _D4 and their inversion pulses are sequentially applied to the horizontal switch HSW connected to No. ₄ . In this example, the horizontal switch HSW is a CM
Since the transmission gate made of OS is used, the inversion pulse is also applied.

Next, the operation of the active matrix type liquid crystal display device shown in FIG. 5 will be described in detail with reference to FIG. As shown in the timing chart of the figure, sampling pulses are output at sampling timings that overlap the actual signal lines for four lines, and horizontal scanning (actual scanning) is performed on the effective display portion 21. For ease of understanding, only five final sampling pulses φ _L are shown in the timing chart. In the present embodiment, the dummy sampling pulses φ _D1 , φ _D2 , φ are successively added at the timing when the sampling pulse φ _L rises and also overlaps the dummy signal line.
_D3 and φ _D4 are output and horizontal scanning (dummy scanning) of the right non-effective display area is performed. When the sampling pulses φ are sequentially output at such overlapping timings, the potential fluctuation of the gate line X occurs due to the capacitive coupling generated at the intersection of the gate line X and the signal line Y.
Since the capacitive coupling is continued in response to the rising of each sampling pulse φ, the potential of the gate line X continues to fluctuate until the final dummy sampling pulse φ _D4 rises. Last dummy sampling pulse φ _D4
After rising, the potential of the gate line X is attenuated toward the ground level because it is no longer subjected to capacitive coupling.

On the other hand, when each sampling pulse φ falls, the horizontal switch HSW shifts from the on state to the off state. When the HSW is closed, the potential fluctuation of the gate line will conversely jump into each signal line Y due to the aforementioned capacitive coupling. As a result, when the fluctuation of the potential of the gate line X is stopped and the damping is started, this affects the potential of the signal line Y through the capacitive coupling and the damping is also performed. As can be understood from the timing chart of FIG. 6, the potentials _VL-4 , _VL-3 , _VL-2 of the actual signal line,
Regarding V _L-1 and V _L , since the corresponding HSWs are already in the off state, after the potential fluctuation of the gate line is subsided, the attenuation starts all at once and finally a voltage drop of ΔV0 occurs. Therefore, since the voltage drop ΔV0 is the same for all the actual signal lines, the unevenness of the display density does not occur. On the other hand, for example, for the first dummy signal line YD1, after the fluctuation of the potential of the gate line is stopped, the corresponding dummy sampling pulse φ _D1 falls with a delay of one clock. The dummy signal line Y is synchronized with this falling time point.
Since the potential V _{D1 of D1} starts to attenuate, the final voltage drop ΔV1 becomes smaller than ΔV0. Similarly, the potential V _D2 of the second dummy signal line YD2 is further delayed by one clock and starts to attenuate, so that the final voltage drop Δ.
V2 becomes smaller. In this way, the voltage drop of the dummy signal line is different from each other, and the display density varies. However, since the dummy signal line is located in the ineffective display portion, it does not affect the actual image. As described above, the horizontal scanning circuit 24 carries out horizontal scanning for an additional four pixels more than the effective display section 21. Also, H
Four dummy signal lines are provided in the same array as the effective display section 21 including the SW. By providing four dummy signal lines, the potential fluctuation of the gate line continues in the same manner for four pixels even after passing the effective display section 21. Therefore,
The fluctuation of the signal line included in the effective display section 21 does not change rapidly at the terminal end. In this embodiment, four signal lines are horizontally scanned at the same time, but in general, when N signal lines are simultaneously scanned, the number of dummy signal lines may be N or more.

Finally, with reference to FIG. 7, the operation of the left non-effective display portion in the idle state shown in FIG. 5 will be described. As described above, the sampling pulse is not supplied from the horizontal scanning circuit 24 to the non-effective display section on the left side, so that the potential of a certain level is held through the video line 25 in the four dummy signal lines YD. On the other hand, since the vertical scanning circuit 23 sequentially outputs the gate pulse, the thin film transistor Tr forming the dummy pixel 26 latches the held signal level. If the pixel electrode is connected to the thin film transistor Tr, the
Since the C component is applied, the orientation is disturbed, and the image quality is disturbed when it reaches the effective display section 21. Considering this point,
In the present invention, the pixel electrode is removed from the dummy pixel 26 so that the DC component is not applied to the liquid crystal.

[0024]

As described above, according to the present invention, a pixel electrode and an active element for driving the pixel electrode are formed in each pixel region belonging to the effective display portion to form an actual pixel contributing to display. On the other hand, in each pixel region belonging to the non-effective display portion, an active element is formed in a state of lacking a pixel electrode to form a dummy pixel that does not contribute to display. With such a configuration, even if the active element of the dummy pixel is damaged by an external electrical stress or noise, the DC component is not applied to the liquid crystal, and the disturbance of the image quality can be prevented. Alternatively, even when the operation of the dummy pixel is temporarily stopped due to driving conditions or the like, the DC component is not applied to the liquid crystal, so that it is possible to prevent the image quality from disturbing the effective display portion. As described above, it is possible to significantly improve the manufacturing yield of the active matrix liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a schematic equivalent circuit diagram showing a first embodiment of an active matrix type liquid crystal display device according to the present invention.

FIG. 2 is a schematic cross-sectional view showing the structure of an actual pixel included in the first embodiment.

FIG. 3 is a waveform diagram for explaining the operation of the first embodiment.

FIG. 4 is a schematic cross-sectional view showing the structure of a dummy pixel included in the first embodiment.

FIG. 5 is a schematic circuit block diagram showing a second embodiment of an active matrix type liquid crystal display device according to the present invention.

FIG. 6 is a timing chart for explaining the operation of the second embodiment.

FIG. 7 is a timing chart for explaining the operation of the second embodiment.

FIG. 8 is a schematic equivalent circuit diagram showing an example of a conventional active matrix type liquid crystal display device.

9 is a schematic plan view for explaining the problems of the conventional example shown in FIG.

FIG. 10 is a schematic plan view showing another example of a conventional active matrix type liquid crystal display device.

FIG. 11 is a schematic plan view showing another example of the same.

[Explanation of symbols]

 1 Effective Display Area 2 Ineffective Display Area 3 Real Pixel 4 Counter Electrode (Auxiliary Line) 5 Dummy Pixel 6 Drive Substrate 7 Counter Substrate 8 Liquid Crystal 14 Pixel Electrode X Gate Line Y Signal Line Tr Thin Film Transistor (Active Element) LC Liquid Crystal Cell Cs Hold capacity

Claims (4)

[Claims] 1. A panel structure having a drive substrate, a counter substrate, and a liquid crystal held between the drive substrate and the counter substrate, and an effective display unit visible from the outside and a peripheral ineffective display unit shielded from the outside. An active matrix type liquid crystal display device having: a driving substrate having row-shaped gate lines and column-shaped signal lines extending over both the effective display portion and the ineffective display portion, and a pixel region at each intersection of the two. In addition, each pixel area belonging to the effective display area is formed with a pixel electrode and an active element for driving the pixel electrode to form an actual pixel that contributes to display, while each pixel area belonging to the ineffective display area is defined. An active matrix type liquid crystal display device characterized in that an active element is formed in a state where a pixel electrode is not formed in the pixel and a dummy pixel which does not contribute to display is formed. 2. The active element comprises a thin film transistor having a gate electrode, a source electrode and a drain electrode,
In the actual pixel, the gate electrode is connected to the gate line, the source electrode is connected to the signal line, the drain electrode is connected to the pixel electrode, while in the dummy pixel, the gate electrode is connected to the gate line, the source electrode is connected to the signal line. The active matrix liquid crystal display device according to claim 1, wherein the drain electrodes are connected and the drain electrode is in an open state. 3. The non-effective display section is provided in four directions of up, down, left and right so as to surround the effective display section located at the center, and the dummy pixel has a function of protecting at least an internal real pixel from an external electrostatic stress. The active matrix type liquid crystal display device according to claim 1, characterized in that. 4. The non-effective display section is provided at least on the left and right sides of the effective display section, and the dummy pixel has a function of preventing at least nonuniform operation of the actual pixel. Active matrix liquid crystal display device.