JP2000098416A - Liquid crystal display device and its data line drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device and its data line drive circuit in which reducing an area of a device and narrowing a picture frame can be realized, and malfunction of a circuit based on wiring impedance and deterioration of a picture can be prevented. SOLUTION: A liquid crystal display section 10 is constituted by forming gate line drive circuits 12, 13 integrally with the liquid crystal panel section 11, a data line drive circuit 20A and the liquid crystal display section 10 are connected by connecting sections 212-1A to 212-NA based on the mounting technology of TAB and the like, a supply line PL of a signal for drive to be supplied to the gate line drive circuits 12, 13 is wired to a circuit substrate 211A of the data line drive circuit 20A and the connecting sections 212-1A to 212-NA, and a signal for drive is supplied to the gate line drive circuit 12, 13 through this wiring PL.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device and a data line driving circuit thereof.

[0002]

2. Description of the Related Art In recent years, a display panel device using liquid crystal as a display device has made remarkable progress. This display panel device is widely used in a viewfinder and a liquid crystal display panel of a video camera recorder, a television for an automobile, a display panel of a navigation system, a display of a notebook computer, and the like.

Recently, a rear projection type television receiver using a liquid crystal panel, a projector device for directly projecting a screen of a personal computer on a screen without using an OHP, and the like are also becoming popular. There is also a movement to replace the display of a desktop personal computer, which has conventionally used a CRT, with a liquid crystal panel to achieve space and power savings.

[0004] These backgrounds include a liquid crystal panel with higher definition, higher image quality (full color, higher contrast, wider viewing angle, moving image support, etc.) and peripheral technologies (driving circuit / element technology, backlight). , Etc.). With the comprehensive improvement of those technologies, liquid crystal display devices have been used in a wide range of application fields.

Although the image quality of a display panel in a state-of-the-art liquid crystal display device is not inferior to that of a CRT display, there are still many parts that need to be improved. One of them is a driving circuit for a liquid crystal panel.

The driving circuit for a liquid crystal display panel with high definition and high image quality is very large, requires a large number of chips, and requires a high-precision circuit, and the display image quality limits the cost of the display panel. It is one of the big factors to do.
Hereinafter, a conventional driving circuit for a liquid crystal display panel will be described in detail.

Although there are many types of liquid crystal elements, a panel capable of displaying a full-color and moving image is a TFT (Thin).
Most of the so-called “Film Transistor” type has a structure in which a thin film transistor (TFT) is integrated in each liquid crystal element constituting a pixel.

FIG. 3 is a diagram showing a circuit structure of a cell forming a pixel of a TFT type liquid crystal display panel. In the pixel cell of the TFT type liquid crystal display panel, one end of each liquid crystal cell CC is connected to a counter electrode EL as shown in FIG. All the pixel cells are commonly connected to the counter electrode EL. The other end is connected to a TFT provided for each pixel cell. Since TFTs are used as switches,
Although there is no distinction between the source and the drain, it is assumed here that the source is connected to the liquid crystal cell CC for convenience. T
The gate of the FT is connected to a gate drive line GL, and a line for writing pixel data is selected by the drive signal.
The drain is connected to a data line DL to which pixel data to be written to each liquid crystal cell of the selected line is supplied. When the writing time to the selected line is completed, the TFT of that line is turned off, but since the pixel data is the liquid crystal cell CC and the storage capacitor HC, the potential is held until the next writing is performed.

The structure of the pixel cell of the TFT type liquid crystal display panel shown in FIG. 3 is common to all panels. On the other hand, there are several types of TFT structure / manufacturing methods, opposing electrode driving methods, and pixel data driving methods.

The structure / manufacturing method of a TFT is roughly classified into a method using amorphous silicon and a method using poly (polycrystalline) silicon. Since the former does not require a high-temperature process, it is easy to make a large panel using glass as a substrate. The latter requires a quartz substrate because of the high temperature process,
Until now, they have been limited to small panels. Recently, polysilicon T
A technique for forming an FT has also been developed, and a medium-sized panel can be manufactured using a polysilicon TFT type. The mobility of carriers in a polysilicon TFT is about one digit greater than that in an amorphous silicon TFT. Therefore, in the case of an amorphous TFT, its on-resistance is high, and it is necessary to take a considerably long writing time. On the other hand, in the case of a polysilicon TFT, the writing time can be considerably shortened.

In a polysilicon TFT type liquid crystal display device, a peripheral drive circuit such as a gate line drive circuit composed of a shift register or the like can be constructed on a liquid crystal display panel. On the other hand, in the case of a device corresponding to a digital image signal, for example, a digital-analog conversion circuit (DAC) is provided for each data line (column line) on a TFT substrate in the case of a device corresponding to a digital image signal. It is configured. Since circuits such as an amplifier and a buffer cannot be integrally formed on the liquid crystal display panel, a configuration in which a TAB or the like is provided outside the liquid crystal display panel and driven is adopted as the data line driving circuit. Is done.

A polysilicon TFT type digital input data line driving circuit is constructed by providing a reference voltage selection type digital-analog conversion circuit (DAC) for each data line (column line) on a TFT substrate, for example. ing. This reference voltage selection type DAC selects only one of the reference voltage signals input from the outside based on data sampled for each data line. It is suitable as a DAC.

FIG. 4 is a block diagram showing an example of the configuration of a liquid crystal display device having a gate line drive circuit integrally formed with a liquid crystal panel section by using a polysilicon TFT.

In the liquid crystal display device shown in FIG. 4, gate line driving circuits 12 and 13 are arranged on both left and right sides of a liquid crystal panel section 11, which is an effective screen area, and a data line driving circuit 20 is arranged on an upper portion. In the apparatus shown in FIG. 4, a liquid crystal display unit 10 is configured by integrating a liquid crystal panel unit 11 and gate line driving circuits 12 and 13 on a polysilicon TFT substrate.

In the liquid crystal display panel section 10, as shown in FIG. 3, for example, m and n pixel cells composed of liquid crystal cells and TFTs are arranged in the horizontal and vertical directions. The common gate lines (GL1 to GL1) whose gate drive signal terminals of the pixel cells are connected to the gate line drive circuits 12 and 13
GLn) and the data drive signal terminal S is connected to the common data line (DL1) connected to the data line drive circuit 20.
To DLm).

The data line driving circuits 12, 13 are constituted by, for example, shift registers.

In this liquid crystal display device, a power supply voltage and control signal VST for supplying to gate line drive circuits 12 and 13 integrally formed with the liquid crystal display panel by polysilicon TFTs, or a clock signal VCK for vertical synchronization and the like.
The supply lines for 1 and VCK2 are wired in the liquid crystal display unit 10. For example, in the case of a layout in which the gate line driving circuits 12 and 13 are arranged on the left and right sides of the liquid crystal panel section 11 as shown in FIG. The wiring will be long.

The data line driving circuit 20 includes, for example, a sampling circuit for sampling digital image data IMD input from the outside, a line memory for storing data sampled by the sampling circuit based on the control signal CTL, and a line memory for storing the data. DAC that converts the converted data into an analog signal and supplies it to each data line
(Digital-analog conversion circuit).

As described above, the data line drive circuit 20 is disposed outside the liquid crystal display panel. The data line drive circuit 20 has a circuit board 211 on which wiring is mainly formed for power supply lines and signal lines, and a circuit board 211 and a liquid crystal display. The display unit 10 is
Including active elements, for example, TAB (Tape Automated Bond
ing) Connecting parts 212-1 to 212N connected using technology
It consists of. And a power supply voltage, a control signal,
Alternatively, when the clock signals HCK1 and HCK2 are supplied, the circuit unit operates, and finally an analog signal by the DAC is supplied to each data line through each of the connection units 212-1 to 212N.

[0020]

However, as described above, in the conventional liquid crystal display device, the liquid crystal panel 1
1, a power line, a control signal line, and a clock signal line for operating the gate line driving circuits 12 and 13 formed integrally with the power line 1, a power line for operating the external data line driving circuit 20, and a control signal. Since it is necessary to input the line and the clock signal line separately, the peripheral portion (frame FRM) that is not linearly related to the display becomes large in order to secure a space for connection, and is incorporated in a small device. Sometimes it was a problem.

As described above, the power supply lines and the signal lines are arranged in the liquid crystal display panel by arranging the gate line driving circuits 12 and 13 on both the left and right sides of the liquid crystal panel 11 as shown in FIG. In this case, the wiring is long on the left and right. However, the impedance of the power supply line of the layout in the panel may not be able to be reduced too much due to the restriction of the pattern. is there. As described above, when the wiring impedance is high, noise may be generated and a malfunction of the circuit may occur. Similarly, the signal lines may be long on the left and right sides of the panel, but if the impedance of the wiring is high, the signal is degraded and the image quality is degraded.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to realize a device having a small area and a narrow frame, and to prevent malfunction of a circuit based on wiring impedance and deterioration of image quality. And a data line driving circuit for the liquid crystal display device.

[0023]

In order to achieve the above-mentioned object, the present invention provides a method for writing image data supplied from a data processing circuit to a predetermined pixel cell of a liquid crystal panel section. A liquid crystal display device having a driving circuit for driving a predetermined driving line based on a driving signal to be transmitted, wherein the driving circuit is formed integrally with the liquid crystal panel unit to constitute a liquid crystal display unit; The processing circuit is connected to the liquid crystal display unit by a connection unit based on a predetermined mounting technique, and the circuit board and the connection unit of the data processing circuit have a supply line for a drive signal to be supplied to the drive circuit. Wiring is performed, and a driving signal is supplied to the driving circuit through the wiring.

Further, according to the present invention, the liquid crystal panel section is formed integrally with a gate line driving circuit for driving a gate line to which a pixel cell is connected based on a driving signal supplied from the outside. A liquid crystal display device that receives image data, outputs a signal of a level corresponding to input data to a data line connected to a pixel cell, and writes the signal to a predetermined pixel cell of a liquid crystal panel unit. A line drive circuit, which is connected to the liquid crystal display unit by a connection unit based on a predetermined mounting technology, and the circuit board and the connection unit have a supply line for a drive signal to be supplied to the gate line drive circuit. And a driving signal is supplied to the gate line driving circuit through the wiring.

In the present invention, the driving circuit is formed integrally with the liquid crystal panel by a polysilicon TFT.

The mounting technique is a TAB technique.

According to the present invention, the liquid crystal panel section and the drive circuit are integrally formed to form a liquid crystal display section, and the data processing circuit forms a connection section forming a predetermined mounting technology such as TAB. Connected to the liquid crystal display unit via Then, the driving signal to the driving circuit is propagated through the wiring formed on the circuit board and the connection portion of the data processing circuit, and is supplied to the driving circuit. Therefore, the peripheral portion other than the liquid crystal panel portion as the effective screen can be reduced, and the impedance of the wiring can be reduced.

Further, according to the present invention, the liquid crystal panel section and the gate line driving circuit are integrally formed to form a liquid crystal display section, and the data line driving circuit forms a predetermined mounting technology such as TAB. Connected to the liquid crystal display unit via a connection unit. Then, a driving signal to the gate line driving circuit is propagated through a wiring formed on a circuit board and a connection portion of the data line driving circuit, and is supplied to the gate line driving circuit. Therefore, the peripheral portion other than the liquid crystal panel portion as the effective screen can be reduced, and the impedance of the wiring can be reduced.

[0029]

FIG. 1 is a circuit diagram showing one embodiment of a polysilicon TFT type liquid crystal display device according to the present invention.
FIG. 2 is a diagram for explaining a specific wiring configuration of the polysilicon TFT type liquid crystal display device of FIG.

In this liquid crystal display device, gate line driving circuits 12 and 13 are arranged on both left and right sides of a liquid crystal panel section 11 which is an effective screen area, and a data line driving circuit 2 is provided on an upper portion.
0A is arranged. The liquid crystal panel section 11 and the gate line driving circuits 12 and 13 are made of polysilicon TFTs.
The liquid crystal display unit 10 is configured by being integrated on a substrate and housed in the same frame FRM.

In the liquid crystal panel section 11, as shown in FIG. 3, m and n pixel cells PXC composed of liquid crystal cells and TFTs are arranged in the horizontal and vertical directions. Pixel cell PX
Terminals S and G of C are a data drive signal terminal and a gate drive signal terminal, respectively. In the pixel cells PXC arranged on the same horizontal line, the gate drive signal terminals G are connected to the common gate lines GL1 to GLn, and the respective gate lines GL
1 to GLn are connected to the gate line drive circuits 12 and 13. Also, pixel cells P arranged in the same vertical column
XC is a data drive signal terminal S having a common data line DL1.
To DLm, and the data lines DL1 to DLm are connected to the data line driving circuit 20A.

The gate line driving circuits 12 and 13 are basically constituted by shift registers, and include a driving signal VST, a vertical synchronizing signal and a signal VCK as a line clock.
1. VCK2 is connected to the circuit board 2 of the data line drive circuit 20A.
11A, the connection unit 212-1A and the TAB 212-N
A is input through a wiring PL formed in A, and a line selection signal is generated according to the input signal.

The data line drive circuit 20A is provided with digital image data IM supplied as serial data.
D is converted into a parallel analog signal for one line. Specifically, the data line driving circuit 20A includes a sampling circuit 21 for sampling digital image data IMD input from the outside, a line memory 22 for storing data sampled by the sampling circuit 21 based on a control signal CTL, and m data lines D
DACs (digital-
(Analog conversion circuit) 23 (-1 to -m).

The data line driving circuit 20A is arranged outside the liquid crystal display section 10 as described above, but as shown in FIG. 2, a circuit board mainly provided with power supply lines and signal lines is provided. 211A and connection portions 212-1A to 212NA including active elements and connecting the circuit board 21 and the liquid crystal display portion 10 by, for example, TAB technology.
It consists of. Then, the power supply voltage and the control signal H
The circuit unit operates by supplying ST or the clock signals HCK1 and HCK2, and finally an analog signal by the DAC is supplied to each data line through each of the connection units 212-1A to 212NA.

Further, in this liquid crystal display device, the data line driving circuit 20A has a gate line driving circuit 1 formed integrally with the liquid crystal panel section 11 by polysilicon TFT.
A supply line (wiring PL) for a control signal VST for supplying the clock signals VCK1 and VCK2 for vertical synchronization and the like to be supplied to the gate lines 2 and 13 is formed, and a gate line driving circuit is provided through the connection sections 212-1A and 212-NA. 12,1
3 respectively. That is, as shown in FIG. 1, the liquid crystal display device of the present embodiment has a gate line driving circuit 1
Even in the case of a layout in which the layouts 2 and 13 are arranged on both left and right sides of the liquid crystal panel section 11, the gate line drive circuits 12 and 1
3, the control signal VST and the clock signals VCK1, VCK
Circuit line 211A of the external data line drive circuit 20A without arranging the supply lines 2 long on the left and right sides of the panel unit.
Frame F through the connection parts 212-1A and 212-NA.
The left and right sides of the upper part of the RM are connected by short wires. Therefore, since most of the wiring length can be formed using copper foil or the like, low-impedance wiring is possible.

Next, the operation of the above configuration will be described. Clock signals HCK1, HCK2, and image data IM
D is transmitted to the wiring formed on the circuit board 211A of the data line driving circuit 20A and supplied to the sampling circuit 21. Further, the drive signal VST and the clock signal VCK
1, VCK2 is the circuit board 2 of the data line drive circuit 20A.
11A formed on the wiring and connecting portions 212-1A, 22-1A
The signals are supplied to gate line drive circuits 12 and 13 each composed of a shift register formed integrally with the liquid crystal panel section 11 through 12-NA wiring.

In data line drive circuit 20A, sampling circuit 21, for example, a shift register, uses clock pulse signal HCK in synchronization with clock signal HCK1.
2 are shifted by m stages, and m sampling pulse signals are sequentially output to m switch circuits that operatively connect the data signal lines and the line memory 22. The data transmitted through the data signal line is turned on / off by the sampling pulse signal output from the shift register.
The signals are sequentially sampled through the switch circuit that is turned off, and stored in a predetermined area of the corresponding line memory 22. The pixel data stored in the line memory 22 includes DACs 23-1 to 23-m provided corresponding to each data line.
Is converted to an analog signal, and the corresponding data line DL1
To DLm as an analog signal.

In the gate line driving circuits 12 and 13, wirings and connecting portions 212-1A and 212-NA formed on the circuit board 211A of the data line driving circuit 20A are provided.
A line selection signal is generated based on the drive signal VST and the clock signals VCK1 and VCK2 input through the wiring PL, and is supplied to predetermined gate lines GL1 to GLn. As a result, the image data is written in parallel to the m pixel cells. Since the drive signal VST and the clock signals VCK1 and VCK2 are supplied through low-impedance wiring, malfunction of the circuit and deterioration of image quality due to wiring impedance do not occur.

As described above, according to the present embodiment, in the case of the layout in which the gate line driving circuits 12 and 13 are arranged on both left and right sides of the liquid crystal panel section 11, the control to the gate line driving circuits 12 and 13 is performed. Signal VST, clock signal V
The supply lines for CK1 and VCK2 are short on both left and right sides of the upper part of the frame FRM through the circuit board 211A of the external data line drive circuit 20A and the connection parts 212-1A and 212-NA without long wiring on the left and right of the panel unit. The liquid crystal panel unit 1 as an effective screen is configured because it is connected by wiring.
There is an advantage that the peripheral portion other than 1 can be made smaller, the device can be made smaller in area and the frame can be narrowed, and the cost can be reduced. Further, since the impedance of the wiring can be reduced, malfunction of the circuit based on the wiring impedance and deterioration of image quality can be prevented.

In the present embodiment, the image data is described as a digital signal. However, it is needless to say that the present invention can be applied to the case of an analog signal, and the same effects as those described above can be obtained.

[0041]

As described above, according to the present invention,
There are advantages in that the area of the device can be reduced and the frame can be narrowed, and malfunction of the circuit based on wiring impedance and deterioration of image quality can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a polysilicon TFT liquid crystal display device according to the present invention.

FIG. 2 is a view for explaining a specific wiring configuration of the polysilicon TFT type liquid crystal display device of FIG. 1;

FIG. 3 is a diagram showing an equivalent circuit of a pixel cell of a TFT type liquid crystal display panel.

FIG. 4 is a circuit diagram showing a configuration example of a conventional polysilicon TFT type liquid crystal display device.

[Description of Signs] 10: Liquid crystal display unit, 11: Liquid crystal panel unit, 12, 13, ...
Gate line drive circuit, 20A ... data line drive circuit, 21 ...
Sampling circuit, 211A ... circuit board, 212A-1
~ 212-NA ... connection part, 22 ... line memory, 23A
-1 to 23A-m ... Digital-analog conversion circuit (DA
C).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H092 GA51 GA59 KA04 KA07 NA07 NA25 PA06 5C006 AA01 AA02 AA16 AF35 AF83 BB16 BC13 BC20 BC23 BF03 BF05 BF11 FA31 FA37 FA41

Claims (6)

[Claims] When driving image data supplied from a data processing circuit to a predetermined pixel cell of a liquid crystal panel section, a driving circuit for driving a predetermined driving line based on a driving signal supplied from the outside. A liquid crystal display device having a circuit, wherein the driving circuit is formed integrally with the liquid crystal panel unit to constitute a liquid crystal display unit, and the data processing circuit is based on a predetermined mounting technology for the liquid crystal display unit. A drive signal supply line to be supplied to the drive circuit is wired to the circuit board and the connection portion of the data processing circuit, the drive signal being supplied to the drive circuit through the wiring. Liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the driving circuit is formed integrally with the liquid crystal panel by a polysilicon TFT. 3. The liquid crystal display device according to claim 1, wherein said mounting technology is a TAB technology. 4. A liquid crystal panel is formed integrally with a gate line driving circuit for driving a gate line to which a pixel cell is connected based on a driving signal supplied from the outside to form a liquid crystal display unit. A data line driving circuit of a liquid crystal display device that receives image data, outputs a signal at a level corresponding to input data to a data line to which a pixel cell is connected, and writes data to a predetermined pixel cell of a liquid crystal panel unit. A connection line based on a predetermined mounting technique is connected to the liquid crystal display unit, and a supply line of a driving signal to be supplied to the gate line drive circuit is wired to the circuit board and the connection unit. A data line driving circuit of a liquid crystal display device for supplying a driving signal to the gate line driving circuit through a wiring. 5. The data line drive circuit of a liquid crystal display device according to claim 4, wherein said drive circuit is formed integrally with a liquid crystal panel by a polysilicon TFT. 6. The data line driving circuit for a liquid crystal display device according to claim 4, wherein said mounting technology is a TAB technology.