JPH0470625A - Driving device for liquid crystal display - Google Patents

Abstract

PURPOSE:To attain the miniaturization of an operational amplifer for power source, the smoothing of the fluctuation of a voltage, and the reduction of stroke by performing control so as to set the polarity of voltages applied to bi-sected electrodes, respectively at the one opposite to each other. CONSTITUTION:This device is equipped with a control block 1 which controls the output voltage of a driver circuit 2 s as to set the polarity of the voltages applied to the bi-sected electrodes 4a, 4b and 5a, 5b, respectively at the one opposite to each other. For example, in a period A when a certain one picture is generated, the voltages to be applied to the upper side common electrode 4a are set at V2, VEE, and the voltages applied to the upper side segment electrode 5a at V1, V3, and also, the voltages to be applied to the lower common electrode 4b at V1, V5, and the voltages applied to the lower side segment electrode 5b at V4, VEE, and the control so as to use each voltage simultaneously is performed. Therefore, the power source origin of a current consumed simultaneously can be dispersed. Thereby, it is possible to miniaturize the operational amplifier used in a power source, to smooth the fluctuation of the voltage, and to reduce the stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a driving device for a matrix-driven liquid crystal display that divides each electrode into two systems and displays two screens at the same time.

(Prior Art) In recent years, liquid crystal displays with large display screens have been put into practical use.This liquid crystal display is designed to drive liquid crystal elements by mounting a large number of driver ICs on one display. Figure 5 shows the power supply configuration for driving the liquid crystal when the screen is divided into upper and lower halves and displayed simultaneously in a simple matrix driven liquid crystal display, for example.This power supply is connected in series. Consists of four connected fixed resistors R8 and variable resistors VR, and four operational amplifiers (operational amplifiers) Ql to Q4 whose voltage at each connection point is supplied to the non-inverting input terminal, and the inverting input of each operational amplifier Q1 to Q4. The terminal is connected to the output terminal.With this configuration, ■1 to ■5 and VE
Six types of voltages can be obtained.

When the screen is divided into upper and lower halves, the segment electrodes (signal electrodes) are also divided into two systems, and the upper and lower screens are simultaneously line-sequentially scanned line by line. At this time, each common electrode (
The voltages from the power source applied to the scanning electrodes) and the segment electrodes are as shown in FIG.

That is, the voltages applied to the upper and lower segment electrodes and the common electrode are normally controlled as follows.

(a) The OFF voltage of the upper segment electrode is v3
(V4), the off voltage of lower segment ZVI is also V3
(V4).

(b) The ON voltage of the upper segment electrode is V +
(V P, E), the on-voltage of the lower segment electrode also becomes V + (V EE).

(c) When the non-selection voltage of the upper common electrode is v2 (VS), the non-selection voltage of the lower common electrode is also V2 (VS).

(d) The selection voltage of the upper common electrode is Vl (VEE)
At this time, the selection voltage of the lower common electrode is also V, (VB2).

Since each electrode is driven as described above, in the first period A in FIG. 6, v5. The power consumption at the voltage of v, , VEE is large, and in the next B period, the power consumption is v2°V3. The power consumption at the voltage V increases.

In other words, the current flowing through the operational amplifiers Q1 to Q4 or the power supply line in FIG. 5 increases for 1/2 period and decreases for 1/2 period. During this time, the operational amplifiers Q1 to Q4 supply current flowing to all driver ICs.

[Invention or problem to be solved]

In conventional liquid crystal display drive devices, as mentioned above, the current flowing through the power supply operational amplifier or the power supply line is
2 period is large and 1/2 period is small, therefore,
The power consumption of the operational amplifier increases, necessitating the use of a large-capacity operational amplifier, and fluctuations in the power supply line also increase, leading to problems such as increased crosstalk due to voltage fluctuations.

This invention was made in view of these problems, and aims to reduce the size of operational amplifiers used in power supplies, and to provide a drive device for liquid crystal display devices that has small voltage fluctuations and reduces crosstalk. The purpose is to obtain.

[Means for Solving the Three Problems] The liquid crystal display driving device of the present invention is a matrix-driven liquid crystal display driving device that divides each electrode into two systems and displays two screens at the same time. The device is equipped with a control unit that controls the polarity of the voltage applied to the electrodes to be opposite to each other.

[Effect]

In the liquid crystal display driving device of the present invention, since the polarity of the voltage applied to each of the two divided electrodes is controlled to be opposite to each other, the current consumption is smoothed in each period.

〔Example〕

FIG. 1 is a block diagram showing a schematic configuration of a driving device for a liquid crystal display according to the present invention. In the figure, reference numeral 1 denotes a control unit that controls the output voltage of the driver circuit 2 that is integrated into an IC, and controls the polarity of the voltage applied to each electrode divided into two systems to be opposite to each other. 3 is an LCD matrix panel of a liquid crystal display driven by a driver circuit 2 in a simple matrix, the display screen of which is divided into two, and both screens are displayed at the same time.

FIG. 2 is a diagram showing the electrode structure of the LCD matrix panel 3, in which each electrode is divided into two systems. In the figure,
4a is an upper common electrode (running 'f electrode) which is a horizontal electrode;
b is a lower common electrode, and these common electrodes 4a and 4b
are arranged in 2YmPIk. Reference numeral 5a indicates an upper segment electrode (i.e., a vertical electrode), 5b indicates a lower segment electrode, and X stiff segment electrodes 5a and 5b are arranged vertically.

As shown in Figure 5, there are six different voltage values to be applied to each electrode of the liquid crystal display, and by alternately selecting and applying four of these values, an alternating current voltage can be generated. It is being synthesized. In addition, the driver ■c (triver circuit 2) for ordinary simple matrix driving is formed of CuO2,
When switching the voltage, a current of several milliamperes per output is consumed as a through current for several hundreds of nanoseconds. In this embodiment, in order to reduce this current consumption, the voltages applied to the upper screen and the lower screen are always reversed by the control unit 1. Figures 3 and 4
The figure shows an example of controlling the voltage applied to each electrode.

That is, for example, in period A for creating one screen, the voltage applied to the upper common electrode 4a is 2°VEE, the voltage applied to the upper segment electrode 5a is V, V3, and the voltage applied to the lower common electrode 4b is The voltage is V,,V5. The voltages applied to the lower segment electrode 5b are V 4 and V
EE, and control so that all voltages are used simultaneously. Similarly, during the B period for creating the next screen, all the voltages shown in FIG. 5 are controlled to be used. Due to two reasons, −
It is possible to disperse the power light of the current consumed at each time, and it is possible to smooth out the current consumption. Therefore, the operational amplifier of the power supply shown in FIG. 5 can be made smaller, and crosstalk can be reduced by smoothing voltage fluctuations.

In addition, even in a drive method that changes AC multiple times during the creation period of one screen, by controlling the polarity so that the voltage direction applied to the upper and lower screens is always opposite, the amount of current consumed at each voltage is distributed. Similarly, it is possible to smooth out the current consumption.

(Effects of the Invention) As described above, according to the present invention, since the polarity of the voltage applied to each of the two divided electrodes is controlled so as to be opposite to each other, the operational amplifier used for the power supply can be miniaturized. This also has the effect of reducing voltage fluctuations and reducing crosstalk.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a driving device for a liquid crystal display according to the present invention, FIG. 2 is a layout diagram showing the electrode structure of the LCD matrix panel of FIG. 1, and FIG. 3 is a common diagram of the LCD matrix panel of FIG. FIG. 4 is a waveform diagram of the voltage applied to the segment electrodes in FIG. 2. FIG. 5 is a circuit diagram showing the configuration of the power supply used in the liquid crystal display. The figure is a waveform diagram of voltages applied to each electrode of a conventional device. 1-=-...Control unit 2-----Driver circuit 3-----L CD matrix panel 4 a=
−=・Upper common electrode 4 b −−−−−Lower common electrode 5 a−−−− Upper segment electrode 5b −−
・Lower segment electrode QINQ4...Operative amplifier Figure 3 Applicant Stanley Electric Co., Ltd. Figure 4 Diagram

Claims (1)

[Claims] In a driving device for a matrix-driven liquid crystal display that divides each electrode into two systems and displays two screens at the same time, control is performed to control the polarity of the voltage applied to each of the two divided electrodes to be opposite to each other. 1. A driving device for a liquid crystal display device, comprising: a drive device for a liquid crystal display device.