JPH055865A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To eliminate the variance of output voltage by generating a prescribed voltage as the correction voltage value of each data driver to correct the voltage values of analog data input signals applied to plural data drivers. CONSTITUTION:This device consists of a liquid crystal display panel 1, a gate driver 2, data drivers 3, a counter part 4, a voltage generating part 5 and a voltage correcting part 6. A prescribed voltage corresponding to the counted value of the counter part 4 is generated as the correction voltage value of each data driver 3 by the voltage generating part 5 at each time of arrival of the counted value at a preliminarily set prescribed value, and the voltage values of analog data input signals applied to plural data drivers 3 are corrected by the voltage correcting part 6 based on the voltage value generated by the voltage generating part 5. That is, proper analog data is inputted to each data driver 3 by the voltage correcting part 6 to correct the variance of output voltage among data drivers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device,
Specifically, thin film transistors (TFTs) suitable for use in the field of flat panel displays
to a) active matrix type liquid crystal display device. In recent years, ordinary cathode ray tubes (CRT: Cathode Ray)
Since a liquid crystal display device (LCD) is extremely thin and consumes less power than a display device using a tube, many liquid crystal display devices (LCD: Liquid Crystal Display) have been developed to become the mainstream of future display devices.

Liquid crystal display devices currently on the market are roughly classified into two types, active matrix type and simple matrix type liquid crystal display devices. Among them, a thin film transistor which is a three-terminal element is used. The active matrix type liquid crystal display device has been particularly noted because it can obtain a high image quality comparable to that of a CRT. The active-matrix liquid crystal display device can perform the same operation as individually driving the cells that form a plurality of pixels, and even if the number of lines to be displayed increases as the display capacity increases, the simple matrix It has the advantage that the drive duty ratio does not decrease and the contrast and viewing angle decrease like the matrix type does not occur, and it is possible to control fine halftones, so it is a thin flat panel display. Is expanding its application as

However, in the active matrix type liquid crystal display device, since the data driver has a circuit structure mainly composed of analog circuits, the chip size becomes large when the data driver part is made into an LSI, and compared with a digital circuit. Since the manufacturing yield is low, the cost of the liquid crystal display device as a whole increases. This is particularly remarkable when manufacturing a display device having a large screen, and therefore, those currently put into practical use are limited to those having a relatively small screen size.

Therefore, there is a demand for an active matrix type liquid crystal display device which realizes a high manufacturing yield even with a large screen.

[0005]

2. Description of the Related Art As a conventional liquid crystal display device of this type,
For example, there is an active matrix type liquid crystal display device as shown in FIG. This liquid crystal display device is roughly classified into
The data driver 3 includes a liquid crystal display panel 1, a gate driver 2, and a data driver 3. The data driver 3 includes a plurality of analog drivers that drive the data lines DL in the liquid crystal display panel 1 into a plurality of groups.

That is, by providing a plurality of small data drivers 3 for driving a plurality of data lines DL to drive the data lines DL of the liquid crystal display panel 1 in a divided manner, a relatively inexpensive analog driver is used to activate a large screen. The matrix type liquid crystal display device is driven.

[0007]

However, in such a conventional liquid crystal display device, since the data lines of the liquid crystal display panel are driven by a plurality of data drivers, the following will be described. There was a problem. That is, in the conventional active matrix type liquid crystal display device, an analog driver is used as a data driver for driving.

However, due to the circuit structure of the analog driver, a plurality of operational amplifiers (OP amplifier: OPer) are provided between the input and the output.
ational amplifier) is inserted in series, and is easily affected by variations in semiconductor manufacturing. Therefore, the variation of the output voltage with respect to the input set voltage among the drivers becomes large, and as shown in FIG.
The gradation display at the boundary of the data driver is deviated, and specifically, there is a problem such that a stripe is visible at the boundary of the data driver.

[Object] Therefore, an object of the present invention is to provide a liquid crystal display device which corrects variations in output voltage of a data driver composed of a plurality of analog drivers.

[0010]

In order to achieve the above object, a liquid crystal display device according to the present invention is a liquid crystal display in which a plurality of cells corresponding to intersections of a plurality of gate lines and data lines orthogonal to each other are arranged in a matrix. A panel, a gate driver for selecting an arbitrary cell row in the liquid crystal display panel, and a plurality of data drivers for writing data by applying a predetermined voltage to a data line of the cell row selected by the gate driver, A counter unit that counts the number of pulses of a synchronizing signal in an analog data signal input from the outside, and generates a predetermined voltage according to the count value each time the count value by the counter unit reaches a preset specified number. A voltage generator and an analog amplifier that is applied to each of the plurality of data drivers based on a voltage value generated by the voltage generator. It is configured with a voltage correction unit for correcting the voltage value of the data input signal.

The voltage generating section has a semiconductor memory section for storing data corresponding to the input count value, and a digital / analog converter section for converting a digital output signal from the semiconductor memory section into an analog signal. It is preferable that the semiconductor memory unit is a non-volatile memory.

[0012]

According to the present invention, each time the count value of the counter section reaches the preset specified number by the voltage generating section, a predetermined voltage corresponding to the count value is generated as a correction voltage value of each data driver, and the voltage correcting section The voltage value of the analog data input signal applied to the plurality of data drivers is corrected based on the voltage value generated by the voltage generator.

That is, since the voltage correction unit inputs appropriate analog data to each data driver, variations in the output voltage between the data drivers are corrected.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 4 are diagrams showing an embodiment of a liquid crystal display device according to the present invention, FIG. 1 is a block diagram showing a main configuration of the liquid crystal display device of the present invention, and FIG. 2 is a counter part of the present embodiment. FIG. 3 is a block diagram showing a configuration of a main part of a voltage generation unit according to the present embodiment. FIG. 4 is a block diagram showing a configuration of a voltage correction unit according to the present embodiment.

First, the structure will be described. In FIG. 1, the same numbers as the numbers given to the conventional example shown in FIG. 6 indicate the same parts. The liquid crystal display device of this embodiment is roughly classified into
It includes a liquid crystal display panel 1, a gate driver 2, a data driver 3, a counter section 4, a voltage generating section 5, and a voltage correcting section 6.

As shown in FIG. 2, the counter unit 4 is composed of 4-bit counters 7 and 8, a NOR gate 9 and an OR gate 10, and counts a data synchronization signal (CLOCK) of display data input from the outside. It is a thing. As shown in FIG. 3, the voltage generator 5 includes a 4-bit counter 11, a ROM (Read Only Memory) 12 as a nonvolatile memory which is a semiconductor memory, and a D / A converter 13 which is a digital / analog converter. The counter unit 4 generates a voltage corresponding to the count value output from the counter unit 4.

That is, the data driver 3 that constantly monitors the count value of the counter unit 4 and latches the input data.
Is detected, and a predetermined voltage corresponding to each data driver 3 is switched and output. As shown in FIG. 4, the voltage correction section 6 is composed of an operational amplifier 14 and resistors 15 and 16, and display data (analog voltage) input to the data driver 3 based on the voltage generated by the voltage generation section 5. The correction is added to.

Next, the operation will be described. FIG. 5 is a timing chart for explaining the operation of this embodiment. In addition,
Similar to the conventional example, this timing chart is created based on the case where there are two sets of data drivers 3 and the number of data electrodes driven by one data driver 3 is four, and the same input voltage is used. On the other hand, it is assumed that the output voltage of the data driver 3a in the first stage is shifted to a higher potential side than the data driver 3b in the next stage.

First, the 4-bit counter of the counter section 4 is reset to 0 by the line synchronization signal (LOAD),
The output voltage of the voltage generator 5 is set to V0 (corresponding to the data driver 3a). Here, the data synchronization signal (CLO
CK) is input, the value of the counter unit 4 becomes 1, 2, 3
However, the output voltage of the voltage generator 5 remains V0, and the data driver 3a
In the figure, as shown in (1) to (4), voltage correction proportional to the output voltage V0 is added.

However, when the value of the counter section 4 exceeds 4, the output voltage of the voltage generating section 5 becomes V1 (V1 <V0), and the data driver 3b indicates (5) to (8) in the figure. Thus, a voltage correction proportional to the output voltage V1 is added. As a result, as shown by (11) to (18) in the figure, the output voltages of the data drivers 3a and 3b are the same for the same input voltage.

The potential indicated by A in FIG. 5 is held inside the data driver 3, and is actually output to each data line DL at the timing of B in FIG. As described above, in the present embodiment, it is possible to correct the setting variation of the output power of the data driver, and for example, even when a driving circuit having a large setting variation of the output voltage of the analog driver or the like is used, Full-color display is possible and the cost can be reduced by improving the yield of the data driver.

In the above embodiment, the voltage generator 5 is set to 1
The circuit has been described as an example, but the circuit is not limited to this, and a plurality of voltage generators 5 corresponding to the count value of the counter 4 may be provided. Further, the configuration of the voltage generator 5 is not limited to the configuration of the ROM and the D / A converter. For example, a voltage may be generated by a plurality of semi-fixed resistors (VR) and output by an analog switch or the like.

Further, the data driver 3 is a driver I
The correction is not limited to division by C unit, but a smaller unit, ultimately one data electrode, may be used. The amount of correction by the voltage correction unit 6 is
It is not limited to be constant in C units, but may be variable (for example, proportional to the input data voltage).

[0024]

According to the present invention, the voltage generating unit generates a predetermined voltage corresponding to the count value of the counter unit as a correction voltage value for each data driver each time a preset specified number is reached, and this voltage value is generated. Based on this, the voltage correction unit corrects the voltage value of the analog data input signal applied to the plurality of data drivers.

Therefore, by inputting appropriate analog data to each data driver by the voltage correction unit, it is possible to correct the variation in the output voltage between the data drivers.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a liquid crystal display device of the present invention.

FIG. 2 is a block diagram showing a main configuration of a counter section according to the present embodiment.

FIG. 3 is a block diagram showing a main configuration of a voltage generating section according to the present embodiment.

FIG. 4 is a block diagram showing a main configuration of a voltage correction unit of the present embodiment.

FIG. 5 is a timing chart for explaining the operation of this embodiment.

FIG. 6 is a block diagram showing a main configuration of a conventional liquid crystal display device.

FIG. 7 is a timing chart for explaining the operation of the conventional example.

[Explanation of symbols]

1 liquid crystal display panel 2 gate driver 3 data driver 4 counter section 5 voltage generation section 6 voltage correction section 7,8 4-bit counter 9 NOR gate 10 OR gate 11 4-bit counter 12 ROM (semiconductor memory section) 13 D / A converter (digital / Analog converter) 14 Op-amp 15,16 Resistor

Claims (1)

Claim: What is claimed is: 1. A liquid crystal display panel comprising a plurality of cells, which correspond to intersections of a plurality of gate lines and data lines orthogonal to each other, arranged in a matrix, and an arbitrary one of the liquid crystal display panels. A gate driver for selecting a cell row, a plurality of data drivers for writing data by applying a predetermined voltage to a data line of the cell row selected by the gate driver, and a synchronization signal in an analog data signal input from the outside A counter unit that counts the number of pulses of
A voltage generation unit that generates a predetermined voltage according to the count value each time the count value of the counter unit reaches a preset specified number, and the plurality of data based on the voltage value generated by the voltage generation unit. A liquid crystal display device comprising: a voltage correction unit that corrects a voltage value of an analog data input signal applied to each driver. 2. The voltage generator includes a semiconductor memory unit that stores data corresponding to an input count value, and a digital / analog converter unit that converts a digital output signal from the semiconductor memory unit into an analog signal. The liquid crystal display device according to claim 1, which has. 3. The liquid crystal display device according to claim 2, wherein the semiconductor storage unit is a non-volatile memory.