JPH05313196A - Active matrix type display device - Google Patents

Abstract

PURPOSE:To provide the active matrix type display device which is decreased in defect and improved in yield and can easily specify and correct the defect. CONSTITUTION:Field effect transistors (FRT) 71-7m and 81-8m are connected between connection parts between X drivers 3a and 3b which use 2m signal lines X1-X2m and (n) scanning lines Y1-Yn and drive the signal lines X1-X2m and the signal lines X1-X2m, and terminals of the odd-numbered and even- numbered signal lines X1-X2m. The signal lines X1-X2m and the FETs 71-7m and 81-8m are mutually compatible, so a spot defect and a line defect are easily corrected. The even-numbered or odd-numbered lines of the signal lines X1-X2m can indpendently be selected by the FETs 71-7m, and 81-8m and the places of the defect parts can easily be specified. The line defect due to a disconnection of the signal lines X1-X2m on the FETs 81-8m at the terminals of the signal lines X1-X2m.

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 display device in which an active element is connected to each pixel electrode.

[0002]

2. Description of the Related Art Liquid crystal display devices have come to be used in various fields by taking advantage of their light weight and low power consumption. Among them, liquid crystal display devices capable of multi-gradation display are televisions or personal computers. Has attracted attention as a display.

For example, an active matrix type display device in which each pixel electrode is provided with an active switching element such as a thin film transistor is capable of displaying without crosstalk between adjacent electrodes even with a display having a large number of scanning lines. Therefore, in recent years, it has come to be noticed, and for example, the configuration shown in FIG. 4 is adopted.

As shown in FIG. 4, a plurality of _m signal lines X _{1 to} X _m are provided in parallel on an insulating substrate (not shown), and n signal lines X _{1 to} X _m are perpendicular to the signal lines X _{1 to} X _m . The scanning lines Y _{1 to} Y _n are provided in parallel and arranged in a matrix. In addition, the signal lines X _{1 to} X _m and the scanning lines Y ₁ to
Field effect transistors ₁₁ 1 to 1 _{mn, which} are thin film transistors as switching elements, are formed at the respective intersections with Y _n, and these field effect transistors 1 ₁₁ to 1 _mn include:
The pixel electrodes 2 _{11 to} 2 _mn are connected to each other to form a first electrode substrate. Further, a second electrode substrate having a counter common electrode (not shown) is provided facing the first electrode substrate, and the liquid crystal composition is sandwiched between the first electrode substrate and the second electrode substrate. And constitutes a liquid crystal cell.

Further, each signal line X _{1 to} X _{m of} this liquid crystal cell is
Is connected to an X driver 3 for applying a drive voltage, scan lines Y _{1 to} Y _n are connected to a Y driver 4 for applying a drive voltage, and a control circuit 5 is connected to these X driver 3 and Y driver 4. The control circuit 5 is controlled and driven.

[0006]

However, in the active matrix type display device shown in FIG.
As the screen becomes finer and the screen size becomes larger, millions to millions of active elements and signal lines and scanning lines having the same number of intersections are formed in a large area. And the yield is reduced.

Further, when a line defect or a point defect occurs, it is not easy to identify the line defect or the point defect.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an active matrix type display device in which defects are reduced and yield is improved, and furthermore, defects can be easily identified and repaired. And

[0009]

An active matrix type display device according to claim 1 is provided with a plurality of signal lines and a plurality of scanning lines orthogonal to the signal lines, and at each intersection of these signal lines and the scanning lines. In an active matrix type display device having a substrate on which active elements and pixel electrodes are arranged, the number of signal lines is 2 m, the number of scanning lines is n, and the number of pixel electrodes is m × n. Two active elements are connected to the pixel electrode with one main electrode in common, the control electrodes of the two active elements are connected to the common scanning line, and the other main electrode of the two active elements is connected. Are respectively connected to the two adjacent signal lines, a driver for driving these signal lines is connected to the signal lines, and a connection portion between the driver and the signal lines and an odd number and an even number Those having a switching element to at least one end-to-end of the signal line.

The active matrix type display device according to a second aspect is the active matrix type display device according to the first aspect, wherein a plurality of signal lines are alternately provided with a positive polarity signal voltage and a non-polarity signal for every predetermined number. The voltage and the voltage are alternately applied.

[0011]

According to the first aspect of the present invention, in the active matrix type display device, the number of signal lines is 2 m, the number of scanning lines is n, the connection portion between the driver for driving the signal lines and the signal lines, and the odd-numbered and even-numbered signal lines. Since the switching element is provided on at least one of the ends of the signal line, the signal line and the switching element are compatible with each other, so that it is easy to correct point defects and line defects. It can be independently selected by the switching element of the signal line, the location of the defective portion can be easily specified, and the line defect due to the disconnection of the signal line is automatically resolved when the switching element at the end of the signal line is closed.

The active matrix type display device according to a second aspect is the active matrix type display device according to the first aspect, in which a plurality of signal lines are alternately provided with a positive polarity signal voltage and a non-polarity signal for every predetermined number. Since the voltage is applied alternately, by making the number of signal lines to which the positive and negative signal voltages are applied substantially equal, the polarities of the voltage of the scanning lines are reversed and cancelled, and the potential fluctuation of the scanning lines changes. Can be ignored and the display quality is improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the active matrix type display device of the present invention will be described below with reference to the drawings. Note that FIG.
The parts corresponding to those of the conventional example shown in FIG.

As shown in FIG. 1, a plurality of _2m signal lines X _{1 to} X _2m are provided in parallel on an insulating substrate (not shown),
A plurality of _n scanning lines Y _{1 to} Y _n are provided in parallel to each other in a direction perpendicular to the signal lines X _{1 to} X _{2m and} are arranged in a matrix. In addition, these signal lines X _{1 to} X _2m and the scanning line Y
_At each intersection with _{1 to} Y _n , a field effect transistor ₁₁ 1 to 1 1 which is a thin film transistor as a switching element.
_2mn are formed, and these field effect transistors ₁₁ 1 to 1
_mn are field effect transistors 1 ₁₁ to _{11 which} are adjacent to each other.
Pixel electrodes 2 ₁₁ to each having a common drain of 1 _mn
One end of 2 _mn is connected to form a first electrode substrate. Further, a second electrode substrate on which a not-shown common electrode is provided is provided to face the first electrode substrate,
By these first electrode substrate and second electrode substrate,
The liquid crystal composition is sandwiched to form a liquid crystal cell.

Further, each signal line X _{1 to} X of this liquid crystal cell is
Field-effect transistors 7 _{1 to} 7 _m each composed of a thin film transistor as a switching element on the base end side of _{2 m.}
An X driver 3a and an X driver 3b for applying a driving voltage are connected through the source and drain of the X driver 3a and 3b. The X drivers 3a and 3b are composed of shift registers 3a1 and 3b1 and sample and hold circuits 3a2 and 3b2, respectively. .. The X driver 3a is directly connected to the control circuit 5 via the inverter circuit 9 for inverting the signal polarity, and the X driver 3b is controlled and driven by the control circuit 5.

A Y driver 4 for applying a driving voltage is connected to the scanning lines Y _{1 to} Y _n .

Further, a field effect transistor 8 formed of a thin film transistor as a switching element is provided between the ends of the odd-numbered signal lines X _{1 to} X _2m-1 and the even-numbered signal lines X _{2 to} X _m adjacent to each other. The source and drain of ₁ to 8 _m are connected.

The field effect transistors 7 _{1 to} 7 _m
And the gates of the field effect transistors 8 ₁ to 8 _m ,
A bus line for on / off controlling these field effect transistors 7 _{1 to} 7 _m and field effect transistors 8 ₁ to 8 _m
B1, B2, and B3 are connected to the adjacent ones in sequence.

The other _ends of the pixel electrodes 2 ₁₁ to 2 _mn are connected to the Vcom driving circuit 11 via the counter common electrodes 10a and 10b.

Next, the operation of the above embodiment will be described.

First, when displaying an image, all of the bus lines B1, B2, B3 are set to a high level, and the field effect transistors 7 _{1 to} 7 _m and the field effect transistor 8 ₁ to
_Keep all 8 _m in the ON state and set the adjacent signal line X ₁
And X ₂ , X ₃ and X ₄ , ..., X _2m-1 and X _2m are given the same signal. Therefore, the terminal ends of these adjacent signal lines X ₁ and X ₂ , X ₃ and X ₄ , ..., X _2m-1 and X _2m are short-circuited by the field effect transistors 8 ₁ to 8 _m . That is, a pair of adjacent signal lines X ₁ , X ₂ , X ₃
And X ₄ , ..., X _2m-1 and X _2m , even if the wire breaks only at one place, no line defect occurs. Moreover, even if one odd and even one of the field-effect transistor 1 ₁₁ to 1 _2mn adjacent occurs a failure, if odd and even other one is normal, does not occur point defects.

However, the field effect transistors 7 _{1 to} 7 _m
And field effect transistors 8 ₁ to 8 _m and X driver 3
a, when there is a short circuit between wirings and 3b is the intact cause line defects and point defects, the field effect transistor 7 ₁
To _7-m and the field effect transistor 8 ₁ to 8 _m and X driver 3a, locate the short circuit location between 3b, if cleavage of the short circuit portion lasers, etc., can be eliminated line defect and a point defect. That is, a pair of adjacent signal lines X ₁ and X ₂ , X
₃ and X ₄ , ..., X _2m-1 and X _2m , disconnection and short circuit occur at two or more places, and adjacent field effect transistors 1 ₁₁ to _{12m n} have two odd and even numbers. In addition, since the probability of causing defects is extremely low, a defect-free liquid crystal display device with a high yield can be manufactured.

Next, a method of detecting a defective portion will be described.

First, the bus lines B1 and B3 are set to low level,
When the bus line B2 is set to the high level and an image is displayed, the field effect transistors 7 ₂ are turned on, the field effect transistors 7 ₁ ..., 8 ₁ ... are turned off, and only the even-numbered signal lines X ₂ ... are turned on. The pixel electrodes 2 _{21 of} even columns driven by the X drivers 3a and 3b and using the field effect transistors 1 ₂₁ ...
Only displayed in ~ 2 _mn .

[0025] In addition, the high level of the bus line B1, and the bus line B2, B3 to a low level, when you view the image, the field-effect transistor 7 ₁ ... is turned on, the field-effect transistor 7 ₂ ..., 8 ₁ ... is It is turned off, only the odd-numbered signal line X ₁ is driven by the X drivers 3a and 3b, and the pixel electrodes 2 ₁₁ to 2 ₁₁ of the odd-numbered columns using the field effect transistor ₁₁ 1 are used.
Only displayed in _m-1n . Then, by comparing the displays of these two displayed pixel electrodes 2 ₁₁ to 2 _mn , the field effect transistors 7 _{1 to} 7 _m and the field effect transistors 8 ₁ to 8 _m , the field effect transistors 7 _{1 to} 7 _m, and the electric field. Effect transistors 8 ₁ to 8 _m and X drivers 3a and 3b
The location of the short circuit between the wiring and can be specified.

Further, the X drivers 3a and 3b are arranged above and below in order to widen the mounting pitch of the driver and improve the reliability of the mounting portion. Although a plurality of X drivers 3a and 3b are provided, the built-in driver In that case, even if such redundancy is provided, the cost does not increase, but rather, defects can be corrected and searched, which leads to an improvement in yield.

Further, the non-inverted display signal is applied to the X driver 3a, and the inverted display signal is applied to the X driver 3b via the inverter circuit 9 to set one line, and the Y driver 4 is set. Signal voltages are simultaneously output from the X drivers 3a and 3b corresponding to the gate voltages of the field effect transistors ₁₁ 1 to 12 _mn applied to the scanning lines Y _{1 to} Y _n . In this case, the X driver 3a when the positive signal voltage is applied to the signal lines X ₁ to X _2m, that signal voltage of negative polarity from the X driver 3b to the signal lines X ₁ to X _2m is applied, The polarity of the applied signal voltage is alternately inverted every two signal lines X _{1 to} X _2m . Therefore, ignoring the scan lines Y ₁ to Y _n and the counter common electrode 10a, by the polarity of the voltage induced in 10b is canceled becomes opposite, the scanning lines Y ₁ to Y _n and the counter common electrode 10a, a potential fluctuation of 10b That is, a predetermined signal voltage can be applied to the liquid crystal cell. The polarity of the data voltage applied to the signal lines X _{1 to} X _2m is switched in a predetermined cycle during one frame period.

FIG. 2 shows the intensity of transmitted light of the liquid crystal by the signal voltage, that is, the luminance characteristic. Although it depends on the liquid crystal material, the range of the signal voltage for changing the brightness is generally about 2V. Therefore, when the liquid crystal has such characteristics, even if the variation ΔV of the output offset voltage of the sample and hold circuits 3a2 and 3b2 is about 100 mV, the transmitted light intensity differs by about 10% depending on the state. As described above, a luminosity difference that can be recognized by human eyes is generated.

Therefore, one set of shift registers 3a1,
In the X drivers 3a and 3b composed of 3b1 and the sample and hold circuits 3a2 and 3b2, the sample and hold circuits 3a2 and 3b2 in the X drivers 3a and 3b have variations in offset voltage. 3a, occurs uneven brightness is different voltage applied for variations offsets for each pixel electrode 2 ₁₁ to 2 _mn corresponding to 3b. In order to solve such uneven brightness, X
Signal line X1 which is connected to the driver 3a, X2, X _5,
X ₆ , ..., the common electrode 10 facing the upper pixel electrodes 2 ₁₁ to 2 _m-2n
a and the signal lines X ₃ , X ₄ , X connected to the X driver 3b
_7, X _8, the counter common electrode of the pixel electrode 2 ₃₁ to 2 _mn on ......
A voltage having a level difference that corrects the offset variation of the X drivers 3a and 3b is applied to the pair of 10b.

For example, when the offset voltage of the X driver 3a is lower than that of the X driver 3b by ΔV, the X driver 3a
And the pixel electrode 2 ₁₁ ~2 _m-2n operated by 3a, X driver
In the pixel electrodes 2 ₃₁ to 2 _mn operated by 3b, a brightness difference corresponding to the potential difference ΔV occurs. In this case, the voltage of the counter common electrode 10a corresponding to the X driver 3a is set to the counter common electrode 10b.
The voltage applied to the pixel electrodes 2 ₁₁ to 2 _m-2n corresponding to the X driver 3a and the pixel electrode 2 ₃₁ corresponding to the X driver 3b by lowering the voltage ΔV from the voltage applied to the X driver 3a.
The voltages applied to ˜2 _mn are the same, and high image quality without uneven brightness can be obtained.

That is, by not making all the common electrodes 10a and 10b electrically common but making them common to each X driver 3a and 3b, the variation in the output offset voltage of the X drivers 3a and 3b is corrected by the DC potential. each counter common electrode 10a potential that does not cause brightness unevenness, by applying to 10b, X driver 3a, even if there are variations in the output offset voltage of 3b, the liquid crystal of each pixel electrode 2 ₁₁ to 2 _mn The variation in applied voltage can be reduced.

Next, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 3 is configured for color in the embodiment shown in FIG.
3a and 3b are composed of three X drivers 3ar, 3br, 3ab, 3bb, 3ag and 3bg for red, blue and green respectively, and X drivers 3br, 3bb and 3ag for red, blue and green. Is connected to the control circuit 5 via inverter circuits 9r, 9b, 9g. Further, the counter common electrode 10 is electrically connected in common.

The circuit shown in FIG. 3 also operates similarly to the circuit shown in FIG.

[0035]

According to the active matrix type display device of the first aspect, the number of signal lines is 2 m, the number of scanning lines is n, the connection portion between the driver for driving the signal lines and the signal lines, and the odd number and the even number. Since the switching element is provided on at least one of the ends of the second signal line, the signal line and the switching element are compatible with each other, making it easy to correct point defects and line defects. Or the odd number can be selected independently by the switching element of the signal line, the location of the defective part can be easily specified, and the line defect due to the disconnection of the signal line can be automatically eliminated by closing the switching element at the end of the signal line. it can.

According to the active matrix type display device of the second aspect, in the active matrix type display device of the first aspect, a plurality of signal lines are alternately provided with a positive polarity signal voltage and a non-polarity for every predetermined number. Since the signal voltage of the scanning line is applied alternately, the polarity of the voltage of the scanning line is reversed and canceled by making the number of signal lines to which the positive and negative signal voltages are applied almost equal. The potential fluctuation can be ignored, and the display quality can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of an active matrix display device of the present invention.

[Fig. 2] Same as above Same as transmitted light intensity (luminance) of liquid crystal by signal voltage
FIG. 6 is a voltage transmitted light intensity characteristic diagram showing

FIG. 3 is a circuit diagram showing an active matrix display device of another embodiment.

FIG. 4 is a circuit diagram of a conventional active matrix display device.

[Explanation of symbols]

1 ₁₁ to 1 _mn field effect transistor Y ₁ as field effect transistors 8 ₁ to 8 _m switching elements as a field effect transistor 2 ₁₁ to 2 _mn pixel electrodes 3a, 3b X driver 7 ₁ to _7-m switching element as an active element ~ Y _n scanning line X ₁ ~ X _{2 m} signal line

Claims (2)

[Claims] 1. An active device comprising a plurality of signal lines and a plurality of scanning lines orthogonal to the signal lines, and an active element disposed at each intersection of the signal lines and the scanning lines and a substrate on which pixel electrodes are formed. In the matrix-type display device, the number of signal lines is 2 m, the number of scanning lines is n, the number of pixel electrodes is m × n, and one main electrode is common to each pixel electrode. Connect the two
The control electrodes of the active elements are connected to the common scanning line, the other main electrodes of the two active elements are connected to the two adjacent signal lines, and these signal lines are connected to the signal lines. An active matrix display characterized in that a driver to be driven is connected, and a switching element is provided in at least one of a connecting portion between the driver and the signal line and an end of the odd-numbered and even-numbered signal lines. apparatus. 2. The active matrix type display according to claim 1, wherein a positive polarity signal voltage and a non-polarity signal voltage are alternately applied to the plurality of signal lines for every predetermined number. apparatus.