JPH11249627A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously realize the reducing of the number of driving lines from source drivers and the coping with a dot inversion driving without being affected by the restriction of high speed polarity changeovers or the like in the source drivers. SOLUTION: This liquid crystal display device is provided with the plural pixels 1 two dimensionally arranged at intersections of plural rows of scanning lines X and plural columns of signal lines Y and a scanning driver 2 driving respective pixels 1 via plural rows of scanning lines X in a row unit and source drivers 3a, 3b driving respective pixels 1 via plural columns of signal lines Y in a column unit. Driving lines La, Lb from the drivers 3a, 3b are respectively branched into three lines and respective branched lines are respectively connected to signal lines Y via switching elements 4. Moreover, the source driver 3a and the source driver 3b are respectively arranged at one end side and at other end side of the signal lines Y and driving polarities of respective source drivers 3a, 3b are made to be reverse phases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display (L).
CD: Liquid Crystal Display (TAB), especially TAB (Tape Automated)
The present invention relates to an active matrix type liquid crystal display device using bonding technology.

[0002]

2. Description of the Related Art In general, liquid crystal display devices used for OA equipment such as personal computers and word processors, televisions and the like include a simple matrix system and an active matrix system. In particular, in recent years, an active matrix method for realizing high-definition display has been frequently used in order to cope with multi-color display.

Generally, in an active matrix type liquid crystal display device, pixels are provided at intersections of a plurality of scanning lines and a plurality of columns of signal lines. Each pixel is provided with a liquid crystal cell, a capacitor, and a thin film transistor (TFT: Thin Film Transistor). Further, as a driver circuit for driving the liquid crystal, there are provided a vertical drive circuit for driving each pixel via the scanning line and a horizontal drive circuit for driving each pixel via the signal line.

[0006] Among them, a scan driver serving as a vertical drive circuit sequentially scans a scan line every one vertical period (one field period) to select pixels in row units. on the other hand,
A source driver serving as a horizontal drive circuit sequentially samples an input video signal every one horizontal period (1H),
The video signal is written to the pixels in the row selected by the scan driver. As a result, a drive voltage is applied to the thin film transistor of the pixel selected by the scan driver and sampled by the source driver. Then, the light transmittance of the liquid crystal cell changes, and the driving voltage is charged in the capacitor. Thus, the light transmittance of the liquid crystal cell is maintained at a predetermined level for a period corresponding to the charging voltage of the capacitor, and a desired image is displayed.

[0005]

The above-described scan driver and source driver are mounted in a TAB system on a liquid crystal panel in which a plurality of pixels are two-dimensionally arranged. In this TAB mounting, a wiring line is formed on a tape carrier, and a chip-shaped drive circuit (scan driver, source driver) is mounted on the wiring line. And, when mounting on the liquid crystal panel,
The wiring lines on the tape carrier side and the wiring lines on the liquid crystal panel side are aligned and electrically connected by thermocompression bonding or the like.

However, under the current situation where the number of wiring lines is steadily increasing with the increase in the number of colors of the color display, the required number of driver circuits is increased and the cost is increased accordingly. Further, as the number of wiring lines increases, the pitch between the wiring lines becomes narrower. Therefore, when performing the above-described TAB mounting, it is necessary to accurately align the lines.

Therefore, in recent years, there has been proposed a liquid crystal display device in which one drive line extending from a source driver is branched into a plurality of lines, and each branch line is connected to a signal line via a switching element. In this liquid crystal display device, the output of one drive line extending from the source driver is sequentially supplied to each signal line by the operation of the switching element, so that the pixels of the row selected by the scan driver are supplied to the pixels as described above. A video signal is written. If such a configuration is adopted, the number of drive lines from the source driver can be greatly reduced, so that the required number of driver circuits can be reduced and a large pitch between wiring lines can be ensured.

Further, as a preferable driving method of the liquid crystal display device, there is a dot inversion drive for alternately inverting the polarities of video signals applied to adjacent pixels. In this dot inversion drive, current is canceled between adjacent pixels in the horizontal direction (scan direction), so that current concentration on a counter electrode or the like of a liquid crystal cell can be prevented. Deterioration can be avoided.

However, in the liquid crystal display device in which the number of drive lines from the source driver is reduced as described above, if the number of lines is reduced to 1 / n (where n is an odd number), it is necessary to support dot inversion drive. There was a problem that it became difficult. That is, when performing the dot inversion drive in a liquid crystal display device in which the number of drive lines from the source driver is reduced to, for example, 1/3 or 1/9, the polarities of the video signals applied to adjacent pixels are alternated as described above. If it is attempted to invert the polarity, it is necessary to switch the polarities of the drive lines adjacent to each other at a very high speed in the source driver, which makes it difficult to respond.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object the object of being free from restrictions such as high-speed polarity switching in a source driver.
An object of the present invention is to provide a liquid crystal display device that can simultaneously reduce the number of drive lines from a source driver and support dot inversion driving.

[0011]

According to the present invention, a plurality of pixels two-dimensionally arranged at the intersection of a plurality of rows of scanning lines and a plurality of columns of signal lines, and the plurality of pixels are arranged via the plurality of rows of scanning lines. A vertical drive circuit that drives the pixels in rows, and a horizontal drive circuit that drives the pixels in column units through the signal lines in the plurality of columns. The drive lines are branched into a predetermined number, each branch line is connected to the signal line via a switching element, and the horizontal drive circuit is arranged at one end and the other end of the signal line, respectively, and A configuration is adopted in which the driving polarity of the horizontal driving circuit arranged on the one end side and the driving polarity of the horizontal driving circuit arranged on the other end side are in opposite phases.

In the liquid crystal display device having the above configuration, the drive lines from the horizontal drive circuit are branched into a predetermined number, and each branch line is connected to the signal line via the switching element. As a result, the output of one drive line can be sequentially supplied to a plurality of signal lines, so that the number of drive lines from the horizontal drive circuit can be significantly reduced. In addition, the horizontal drive circuits are arranged at one end and the other end of the signal line, respectively, and the drive polarity of the horizontal drive circuit arranged at one end is opposite to the drive polarity of the horizontal drive circuit arranged at the other end. , The number of drive lines of the horizontal drive circuit is reduced to 1 / n
Even if the number is reduced to n (where n is an odd number), dot inversion driving can be realized without performing high-speed polarity switching in each of the horizontal drive circuits on one end and the other end.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of a liquid crystal display device according to the present invention.
The illustrated liquid crystal display device has a plurality of pixels 1 two-dimensionally arranged at intersections of a plurality of rows of scanning lines X and a plurality of columns of signal lines Y, and has a scan driver 2 as a vertical drive circuit and a horizontal drive circuit. Source driver 3
a and 3b are integrally provided on the same substrate. Each pixel 1 is provided with a liquid crystal cell LC and a thin film transistor TFT for driving the liquid crystal cell LC.

The source drivers 3a and 3b are arranged separately at one end (upper end in the drawing) and the other end (lower end in the drawing) of the plurality of rows of signal lines Y. The drive lines La and Lb drawn from the source drivers 3a and 3b are branched into three systems in the middle of the lines. The branch lines of the drive lines La and Lb are connected to the signal lines Y via the switching elements 4, respectively.
It is connected to the.

Incidentally, in FIG. 1, the source driver 3a,
3b are displayed two by two at the top and bottom, and the number of drivers for each is appropriately set from the relationship between the number of output terminals held by the driver and the required number of drive lines corresponding to the signal lines Y. Also, the connection point of the wiring lines between the TAB-mounted source drivers 3a and 3b and the liquid crystal panel is an intermediate portion between the drive lines La and Lb before branching.

Here, the operation (opening / closing) of each switching element 4 is controlled by three corresponding control lines SL.
The output from the source drivers 3a and 3b is sequentially supplied to each signal line Y in a time-sharing manner.

The drive line La from the source driver 3a provided at one end of the source drivers 3a and 3b provided at one end and the other end of the signal line Y is:
A branch line branched therefrom is connected to an odd-numbered signal line Y from the left side of the figure. On the other hand, in the drive line Lb from the source driver 3b provided on the other end side of the signal line Y, a branch line branched therefrom is connected to an even-numbered signal line Y from the left side in the drawing. In other words, of the signal lines Y adjacent to each other, one signal line Y is connected to the drive line La from the source driver 3a (upper side in the figure), and the other signal line Y is connected to the source driver 3b (lower side in the figure). Has a wiring structure connected to the driving line Lb from the outside.

In the liquid crystal display device having the above configuration, the driving lines La and L from the source drivers 3a and 3b are provided.
b, each signal line Y is AC-driven with a polarity of "+/-" in the upper source driver 3a in the figure, and "-/ +" with a polarity opposite to that of the signal driver Y in the lower source driver 3b in the figure. Writing a video signal to the pixel 1 realizes dot inversion driving in which the polarity of the video signal applied to the adjacent pixels 1 is alternately inverted.

At this time, each source driver 3a, 3
b, the polarity of the drive lines La and Lb is positive (or negative) on one side of the source driver 3a.
In this case, the other source driver 3b only needs to be negative (or positive), so that it is not necessary to switch at a particularly high speed.

Thus, in the liquid crystal display device in which the number of drive lines La and Lb for applying a drive voltage to each signal line Y is reduced to １ ／, it is possible to easily cope with the dot inversion drive. Further, the pitch of the drive lines La and Lb in each of the source drivers 3a and 3b can be increased to twice the pitch of the signal line Y, so that the alignment of the lines in the TAB mounting becomes easy.

In the above embodiment, the driving lines La and Lb of the source drivers 3a and 3b are
By supplying output to each of three signal lines Y,
The application to the liquid crystal display device in which the number of drive lines is reduced to 1/3 has been described.
(Where n is an odd number) it is suitable for application to liquid crystal display devices in general.

Further, even when the present invention is applied to a liquid crystal display device in which the number of drive lines of the source driver is reduced to 1 / m (where m is an even number), an effect that a wider pitch between drive lines can be secured can be obtained. .

[0023]

As described above, according to the present invention, the drive lines from the horizontal drive circuit are branched into a predetermined number, and each branch line is connected to a signal line via a switching element. The number of drive lines from the drive circuit can be significantly reduced, and the drive polarity of the horizontal drive circuit located at one end of the signal line and the drive polarity of the horizontal drive circuit located at the other end are reversed. By using the phases, it is possible to perform dot inversion driving without requiring high-speed polarity switching in both horizontal driving circuits. As a result, a liquid crystal display device that achieves lower cost by reducing the required number of horizontal drive circuits, easier alignment with an increase in wiring line pitch, and higher image quality by realizing dot inversion drive at the same time. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of a liquid crystal display device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pixel, 2 ... Scan driver, 3a, 3b ... Source driver, 4 ... Switching element

Claims (1)

[Claims] 1. A plurality of pixels two-dimensionally arranged at an intersection of a plurality of rows of scanning lines and a plurality of columns of signal lines, and the plurality of pixels are driven in units of rows via the plurality of rows of scanning lines. In a liquid crystal display device including a vertical drive circuit and a horizontal drive circuit that drives the plurality of pixels in units of columns via the plurality of columns of signal lines, the drive lines from the horizontal drive circuit are branched into a predetermined number. And connecting each branch line to the signal line via a switching element, arranging the horizontal drive circuits at one end and the other end of the signal line, respectively, and a horizontal drive arranged at the one end. A liquid crystal display device wherein the drive polarity of a circuit and the drive polarity of a horizontal drive circuit disposed on the other end side are in opposite phases.