JPH0915646A - Active matrix liquid crystal display element - Google Patents

Abstract

PURPOSE: To simplify the connection of the electric circuit of a liquid crystal display element and to miniaturize it by providing a resistance inserted between a common electrode and a shared terminal on the substrate forming a switching element. CONSTITUTION: A shared line 66 is wired on the peripheral part of the substrate 11, and a common voltage VCOM being the voltage common to the common electrode 14 and a compensation capacity line CS is applied from the outside to the shared line 66 through its terminal part. The compensation capacity line CS is connected to the shared line 66 directly, and further, the common electrode 14 is connected to the shared line 66 through a connection pad 65, a common electrode signal line 62 and an additional resistance 61. Thus, the voltage is applied to the common electrode 14 and the compensation capacity line CS through the shared terminal, and the number of terminals are reduced. Further, by adding the common voltage VCOM inverting its polarity at every prescribed period to the common electrode 14 through the additional resistance 61, the distortion of the voltage of the common electrode 14 is reduced when a data line driver 42 outputs a preset signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix liquid crystal display device, and more particularly to an active matrix liquid crystal display device in which deterioration of display image quality due to distortion of a voltage waveform applied to a common electrode (counter electrode) is suppressed.

[0002]

2. Description of the Related Art Active matrix liquid crystal display elements are
A liquid crystal is arranged between one substrate on which a common electrode is formed and the other substrate on which a plurality of pixel electrodes and switching elements connected to the pixel electrodes are formed. In the active matrix liquid crystal display element, a polarity reversal method in which the polarity of the drive voltage is reversed every predetermined period is generally adopted in order to prevent the DC voltage component from being biasedly applied to the liquid crystal.

However, in the polarity inversion type active matrix liquid crystal display element, the voltage of the common electrode is affected by a preset signal (a signal for presetting the potential of the pixel electrode to a predetermined value) output from the data line driver. A distorted pulse is generated in the voltage waveform (rising or falling) at the time of inversion. The distorted pulse causes display unevenness of the display image. As a countermeasure against this, a method of adding resistance to the signal line (lead-out line) of the common electrode to dull the distortion pulse is used.

[0004]

Since the resistor for eliminating the influence of the distorted pulse is connected to the outside of the liquid crystal display element, the electric connection becomes complicated and the peripheral circuit becomes large. there were.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an active matrix liquid crystal display device having a simple and small electrical connection structure and capable of displaying a high quality image. Another object of the present invention is to reduce the distortion pulse generated in the voltage of the common electrode when the polarity of the voltage of the data line is reversed.

[0006]

In order to achieve the above object, an active matrix liquid crystal display device of the present invention comprises:
One substrate on which the common electrode is formed, and the other substrate on which the pixel electrode, the switching element, and the compensation capacitance line are formed,
In an active matrix liquid crystal display device including a liquid crystal disposed between both substrates, a common terminal to which a voltage applied to the common electrode and the compensation capacitance line is externally supplied, the common terminal, and the common terminal A means for connecting a compensation capacitance line and a means for connecting the common terminal and the common electrode via a resistor are formed on the other substrate.

The switching element may be formed by a thin film transistor, and the resistor may be formed by using a semiconductor layer used in the thin film transistor in the step of forming the thin film transistor. Further, the resistor may be formed by using a transparent conductive film forming the pixel electrode in the step of forming the pixel electrode.

The common terminal and the common electrode may be composed of a resistor and a conductor connected to the common terminal on the other substrate.

[0009]

According to the above structure, the resistor connected to the common electrode is inserted between the common electrode and the common terminal of the substrate on which the switching element is formed. Therefore, the structure is simple and the size is small. Then, even if the voltage waveform applied to the common terminal from the outside includes a distorted pulse and noise, this resistance makes them dull. Therefore, it is possible to prevent display unevenness due to an abnormal change in the voltage of the common electrode.

If the resistor is formed in the process of forming a TFT or a pixel electrode, for example, the step of manufacturing the resistor can be omitted and the manufacturing process can be simplified.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a sectional structure of an active matrix liquid crystal display device according to an embodiment of the present invention. As shown in the figure, this active matrix type liquid crystal display element is
A pair of insulating transparent substrates 11 and 12 and substrates 11 and 1
A liquid crystal cell 18 composed of a sealing material SC for joining 2 and a liquid crystal 17 sealed between the substrates 11 and 12,
A pair of polarizing plates 21 and 2 arranged with the liquid crystal cell 18 interposed therebetween.
2 is provided.

A common electrode (counter electrode) 14 is provided on the substrate 12.
And an alignment film 16 formed on the common electrode 14.

As shown in FIGS. 1 and 3, a pixel electrode 13 and a TFT as a switching element are provided on the substrate 11.
(Thin film transistor) 31 and scanning line (gate line)
The GL, the data line DL, and the compensation capacitance line CS are formed in a matrix.

The TFT 31 comprises a gate electrode 34, a gate insulating film 35, a semiconductor layer 36, a drain electrode 37 and a source electrode 38 formed on the substrate 11. Each T
The gate electrode 34 of the FT 31 is connected to the scanning line GL of the corresponding row, the drain electrode 37 is connected to the corresponding pixel electrode 13, and the source electrode 38 is of the data line DL of the corresponding column.
It is connected to the. Further, the compensation capacitance line CS is formed so as to be insulated from the pixel electrode 13 by the gate insulating film 35.

An alignment film 15 is arranged on the pixel electrode 13 and the TFT 31.

A common line 66 is provided around the substrate 11 as shown in FIGS. 2 and 3. The common line 66 and the compensation capacitance line C are connected to the common line 66 via its terminal portion.
A common voltage VCOM, which is a voltage common to S, is applied from the outside. The compensation line CS is directly connected to the shared line 66. Further, the common electrode 14 is connected to the common line 66 via the connection pad 65, the common electrode signal line 62, and the additional resistor 61. Additional resistor 61 and common electrode signal line 62
And the connection pads 65 are arranged at four corners of the substrate 11, and the common voltage VCOM is supplied to the common electrode 14 at four locations.

In other words, the compensation capacitance line CS has the common voltage V
COM is electrically directly connected to an external connection terminal (common terminal) applied from the outside, and the common electrode 14 is connected to the common terminal via an additional resistor 61.

The additional resistor 61 is formed in the process of forming the TFT 31 using the same material as the semiconductor layer 36 forming the TFT 31. The connection pad 65 is a sealing material SC
It is arranged outside.

As shown in FIG. 3, the scanning line GL is connected to the scanning line driver 41 at its terminal portion, and the data line DL is
The terminal portion is connected to the data line driver 42. Further, a common voltage (reference voltage) VCOM is externally applied via the terminal portion of the shared line 66. Data line driver 42
Drives the data line DL using a data signal whose polarity is inverted every predetermined horizontal scanning period. The common voltage applied to the common line 66 is inverted in polarity in synchronization with the inversion of the polarity of the data signal.

With such a configuration, the voltage can be applied to the common electrode 14 and the compensation capacitance line CS through the common terminal, and the number of terminals can be reduced. Further, since the common voltage VCOM whose polarity is inverted every predetermined period is applied to the common electrode 14 via the additional resistor 61, when the data line driver 42 outputs the preset signal, the voltage distortion of the common electrode 14 is distorted. Will be reduced. Furthermore, additional resistance 6
1 using the semiconductor layer forming the TFT 31
Since it is formed in the step of forming, no additional step is required for its manufacture.

Next, an example of a method of forming the additional resistor 61 will be described with reference to FIGS. First, FIG.
As shown in FIG. 5, a conductive layer made of aluminum, aluminum alloy, chromium or the like is formed on the substrate 11 by vapor deposition, sputtering or the like, and this is patterned to be shared by the common electrode signal line 62 and the compensation capacitance line CS. The line 66, the gate electrode 34, and the scanning line GL are formed.

After that, as shown in FIG.
100-500 nm thick silicon nitride (Si
A gate insulating film 35 made of N), silicon oxide (SiO), or the like is formed by using plasma CVD or the like.

Next, as shown in FIG. 4C, a contact hole 71 for connecting the additional resistor 61 to the gate insulating film 35 is formed on the common electrode signal line 62 and the common line 66.

Next, as shown in FIG.
A semiconductor layer 36 of amorphous silicon, polysilicon or the like having a thickness of 70 nm is formed by using plasma CVD or the like.

Next, as shown in FIG. 5B, the semiconductor layer 36 is patterned into the element shape of the TFT 31 and the element shape of the additional resistor 61.

Then, the n-type semiconductor layer 72 is deposited by CVD or the like, and a metal layer for forming electrodes such as aluminum or chromium is further formed by sputtering or the like.

Subsequently, as shown in FIG. 5C, the metal layer is patterned into a predetermined shape to form a drain electrode 37, a source electrode 38 and a data line DL. Furthermore, using the formed electrodes and lines as a mask,
The n-type semiconductor layer 72 is patterned by protecting the resistance formation region with a resist or the like, and n of the channel region of the TFT 31 is formed.
The type semiconductor layer and other unnecessary portions of the n-type semiconductor layer are removed. After that, the pixel electrode 13 and the like are formed by a normal process.

In this way, the additional resistor 61 can be manufactured in the manufacturing process of the TFT 31 using the semiconductor layer 36.

An additional resistor 61 is used instead of the semiconductor layer 36.
It may be formed of an ITO (indium-tin oxide) layer. In this case, for example, as shown in FIG.
After forming T31, a contact hole 71 ′ is formed in the gate insulating film 35. After that, ITO is formed on the entire surface by sputtering or the like, and this is patterned to form the pixel electrode 13 and the additional resistor 61 ′ as shown in FIG. 6B.
To manufacture.

The method of manufacturing the resistor is not limited to the above example, and may be formed by any method capable of suppressing an increase in the number of steps depending on the element structure of the TFT 31.

Further, for example, when the connection pad 65 is made of a resin to which a conductive material is added, the connection pad 65 may form an additional resistance by adjusting the amount of the conductive material added.

Further, in the above embodiment, the common line 66 and the common electrode 14 are connected at four corners of the substrate, but the connection points and the number thereof are arbitrary. In the above embodiment, the scanning line driver 41 and the data line driver 42 are connected to the liquid crystal cell 18.
Although the example of arranging the driver outside is shown, the driver may be arranged on the substrate by using the COG method or the like.

[0033]

As described above in detail, according to the present invention, the resistor inserted between the common electrode and the common terminal is provided on the substrate on which the switching element is formed. The connection of the electric circuit is simple and the size can be reduced. Then, when reversing the polarity of the voltage applied to the shared line, the distortion pulse due to the influence of the output signal of the data signal driver can be blunted, and the deterioration of the image quality due to this can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of an active matrix liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is an enlarged view of an end portion of the other substrate shown in FIG.

FIG. 3 is a diagram showing a configuration of the other substrate shown in FIG.

FIG. 4 is a diagram showing an example of a manufacturing process when an additional resistor is formed using a semiconductor layer.

FIG. 5 is a diagram showing an example of a manufacturing process when an additional resistor is formed using a semiconductor layer.

FIG. 6 is a diagram showing an example of a manufacturing process when an additional resistance is formed using ITO.

[Explanation of symbols]

11 ... Substrate, 12 ... Substrate, 13 ... Pixel electrode, 14 ... Common electrode (counter electrode), 15 ... Alignment film, 16 ... Alignment film, 17
... liquid crystal, 18 ... liquid crystal cell, 21 ... polarizing plate, 22 ... polarizing plate, 31 ... TFT (thin film transistor), 34 ... gate electrode, 35 ... gate insulating film, 36 ... semiconductor layer, 37
... Drain electrode, 38 ... Source electrode, 41 ... Scan line driver, 42 ... Data line driver, 61 ... Additional resistance,
62 ... Common electrode signal line, 65 ... Connection pad, 66 ...
Common line, 71 ... Contact hole, 72 ... N-type semiconductor layer, DL ... Data line, GL ... Scan line, CS ... Compensation capacitance line

Claims (4)

[Claims] 1. A substrate comprising one substrate having a common electrode formed thereon, another substrate having a pixel electrode, a switching element and a compensation capacitance line formed thereon, and a liquid crystal arranged between the two substrates. In the active matrix liquid crystal display element, a common terminal to which a voltage applied to the common electrode and the compensation capacitance line is externally supplied, a means for connecting the common terminal and the compensation capacitance line, the common terminal and the common An active matrix liquid crystal display element, characterized in that means for connecting electrodes through a resistor are formed on the other substrate. 2. The switching element is composed of a thin film transistor, and the resistor is formed in the step of forming the thin film transistor.
The active matrix liquid crystal display device according to claim 1, wherein the active matrix liquid crystal display device is formed using a semiconductor layer used in the thin film transistor. 3. The pixel electrode is composed of a transparent conductive film,
3. The active matrix liquid crystal display element according to claim 1, wherein the resistor is formed by using the transparent conductive film in the step of forming the transparent conductive film. 4. The means for connecting the common terminal and the common electrode includes a resistor connected to the common terminal on the other substrate, and a common electrode formed on the one substrate via the resistor. The active matrix liquid crystal display element according to claim 1, comprising a conductor electrically connecting to the common terminal.