JPH1048593A - Method for driving liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized liquid crystal display device of high quality by impressing a correction voltage on a scanning side driving voltage in accordance with the reduction amount of the effective value of the scanning side driving voltage caused by waveform distortion. SOLUTION: The degree of a load is decided in accordance with the number of ON-data transmitted to drivers 6 and 7 on a signal side, then, a time of impressing the correction voltage is adjusted. That is, the number of ONdata is counted by a load decision device 12 in upper and lower screens respectively, and in the case the counted value is zero, the device is set so as not to impress the correction voltage. On the other hand, in the case the counted value is equal to a prescribed value A, the device is set so as to impress the correction voltage at a corresponding clock time. By switching driving power sources (shown by VoH, V0, V5 and V5L in figure) for the scanning side drivers IC 8 and 9 by switches 10 and 11, the correction voltage is impressed. Thus, the generation of a crosstalk is eliminated, and then, an additional space for the driving circuit is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a driving method of a simple matrix liquid crystal display device.

[0002]

2. Description of the Related Art As a driving method for a simple matrix liquid crystal display device, there is a so-called "voltage averaging method" for averaging voltages at a half-selected point and a non-selected point. FIG. 4 shows a display wiring structure of a simple matrix type liquid crystal display device A using this voltage averaging method. Reference numeral 1 denotes transparent electrodes arranged on a scanning substrate.
Is connected. Similarly, a signal-side driver IC 4 is connected to the transparent electrodes 3 arranged on the signal substrate. The transparent electrode 1 and the transparent electrode 3 intersect with each other to form a display area.
In addition, a driving power supply circuit constituting a voltage averaging method is formed by the signal side driver IC 4.

However, according to such a voltage averaging method, compared with an active matrix liquid crystal display device,
There is a problem that a tailing phenomenon called crosstalk occurs. This crosstalk is caused by the fact that a capacitor is generated at the intersection of the transparent electrode 1 and the transparent electrode 3 so that the applied voltage does not immediately rise and the voltage causes a so-called “waveform rounding” (waveform distortion).

In order to solve this problem, there has been proposed a technique called "sharp addressing" for compensating for a decrease in luminance by applying a correction voltage (Nikkei Micro Device 19).
According to this technique, the occurrence of crosstalk appearing in the vertical direction in the display area shown in FIG. 4 is suppressed.

On the other hand, the problem of crosstalk appearing in the horizontal direction of the display area has been solved by disposing driving circuits (IC) near both ends of the scanning side electrode (transparent electrode 1).

[0006]

However, when similar driving circuits are arranged near both ends of the scanning side electrode,
Further space for the drive circuit is required,
There is a problem in that the external dimensions of the product become large, and it is not possible to meet the market needs for miniaturization of notebook computers and the like.

Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to achieve high quality and small size by a driving method for eliminating crosstalk appearing in a horizontal direction of a display while achieving miniaturization. It is to provide a liquid crystal display device.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method of driving a liquid crystal display device of a simple matrix, wherein a correction is made to the scan-side drive voltage in order to correct the decrease in the effective value of the scan-side drive voltage due to waveform rounding. It is characterized by running voltage.

[0009]

FIG. 1 is a block diagram of a driving circuit used in a method of driving a liquid crystal display device according to the present invention, and FIG. 2 is a driving waveform diagram obtained by using the driving circuit. Also,
FIG. 3 is a conventional drive waveform diagram.

In FIG. 1, 5 is 640 × 3 (R, G,
B) A liquid crystal panel having 480 dots and a duty of 1/240. Based on a conventionally known voltage averaging method, reference numerals 6 and 7 denote signal driver ICs, and 8 and 9 denote scanning driver ICs. , 11 are switches, 12 is a load determiner, and 13 is a bias power supply.

[0011] CP is a data transfer clock, LO
AD indicates a data latch signal, FRAM indicates a scan start signal, DF indicates an AC inversion signal, UD0 to 7 indicate upper screen data, and LD0 to 7 indicate lower signal data.

In the drive circuit block having the above configuration,
When the data transfer clock CP is 8-bit transfer, 240 data transfer clocks CP are sent per line based on the calculation of 640 × 3 ÷ 8.
Therefore, according to this embodiment, the signal side driver 6,
The degree of the load was determined in accordance with the number of ON data sent to 7, and the time for running the correction voltage was adjusted accordingly.

That is, the number of ON data is counted separately for the upper and lower screens in the load determiner 12, and when the counter value is 0, the correction voltage is set so as not to run.
On the other hand, when the counter value is A (any integer from 1 to 1920), the correction voltage is set to run during the clock time corresponding to [A ÷ 8]. The correction power is given by switching the driving power supply (the power supply is indicated as VOH, V0, V5, V5L in the figure) to the scanning side driver ICs 8, 9 by the switches 10, 11.
However, at A ÷ 8, decimals were rounded down.

In the correction voltage adjustment, it is preferable to adjust the voltage value more appropriately according to the size of the liquid crystal panel 5, the cell gap, and the liquid crystal material.

Next, the timing in the driving method of the present invention will be described with reference to FIG. Among the upper halves of these figures, the figures when the time T is further enlarged are shown in the lower halves of the figures.

In these figures, LOAD is a data latch signal, CP is a data transfer clock, SW is a control signal for correction time (the control signals are shown as OU and OL in the figures), and VoH is a correction voltage for V0. , V0, V5 are the ON levels of the signal side driver ICs 6, 7, V2,
V3 is the OFF level, V0 and V5 are the selection levels of the scanning driver ICs 8 and 9, and V1 and V4V are the non-selection levels. V5L is a correction voltage for V5.

In the driving method according to the present invention, for the signal side drivers 6 and 7, the data capturing circuit and the output circuit operate simultaneously. That is, n- on the scanning side
Since the data of the n-th line is output while the data of the first line is being taken in, the data counter also counts the number of ON data at the time of the taking-in, and controls the switching time of the power switch according to the value. I have to. The switching time is set based on the data transfer clock.

Thus, according to the driving method of the present invention, the correction voltage is applied to the scan-side drive voltage corresponding to the effective value decrease of the scan-side drive voltage due to the rounding of the waveform.
Crosstalk was reduced.

It should be noted that the present invention is not limited to the embodiment described above, and various changes and improvements do not hinder the present invention without departing from the gist of the present invention. For example,
In this embodiment, the time during which the correction voltage runs is adjusted. Alternatively, the value of the correction voltage may be changed while keeping the time constant. Alternatively, the adjustment may be performed by a combination of both.

[0020]

As described above, according to the driving method of the liquid crystal display device of the present invention, the correction voltage is applied to the scanning side drive voltage in accordance with the effective value decrease of the scanning side drive voltage due to the waveform rounding. As a result, crosstalk can be eliminated, and no extra space for a drive circuit is required for solving the problem. As a result, a high-quality and small-sized liquid crystal display device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of a driving circuit used for a driving method of a liquid crystal display device of the present invention.

FIG. 2 is a driving waveform diagram according to the driving method of the present invention.

FIG. 3 is a driving waveform diagram according to a conventional driving method.

FIG. 4 is a schematic diagram showing a display wiring structure of a simple matrix type liquid crystal display device.

[Explanation of symbols]

 1,3 Transparent electrode 2,8,9 Scan driver IC 4,6,7 Signal driver IC 5 Liquid crystal panel 11 Switch 12 Load determiner 13 Bias power supply LOAD Data latch signal CP Data transfer clock

Claims (1)

[Claims] 1. A method of driving a liquid crystal display device of a simple matrix, wherein a correction voltage is applied to a scanning-side drive voltage in order to correct a decrease in an effective value of the scan-side drive voltage due to waveform rounding. A method for driving a liquid crystal display device.