JPH087340B2 - Liquid crystal display drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a drive device for a liquid crystal display of a matrisk drive in which each electrode is divided into two systems and two screens are simultaneously displayed.

[Conventional technology]

In recent years, liquid crystal displays with large display screens have been put into practical use. In this liquid crystal display, a large number of driver ICs are mounted on one display to drive liquid crystal elements. FIG. 5 shows a power supply configuration for driving a liquid crystal in the case of a simple matrix drive liquid crystal display, for example, where the screen is vertically divided into two and displayed simultaneously. This power supply is composed of four fixed resistors R _O and a variable resistor VR connected in series, and four operational amplifiers (operational amplifiers) Q1 to Q4 in which the voltage at each connection point is supplied to the non-inverting input terminal.
The inverting input terminals of Q1 to Q4 are connected to the output terminals. With this configuration, six types of voltages V _{1 to} V ₅ and V _EE can be obtained.

When the screen is vertically divided into two, the segment electrodes (signal electrodes) are also divided into two systems, and the upper and lower screens are simultaneously scanned line by line at the same time. At this time, the voltage from the power source applied to each common electrode (scan electrode) and segment electrode is as shown in FIG.

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

(A) The off voltage of the upper segment electrode is V
_{At 3} (V ₄ ), the off voltage of the lower segment electrode is also V
It becomes ₃ (V ₄ ).

(B) The ON voltage of the upper segment electrode is V
_{When 1} (V _EE ), the ON voltage of the lower segment electrode is also V ₁ (V
_EE ).

(C) When the non-selection voltage of the upper common electrode is V ₂ (V ₅ ), the non-selection voltage of the lower common electrode is also V ₂ (V ₅ ).

(D) When the selection voltage of the upper common electrode is V ₁ (V _EE ), the selection voltage of the lower common electrode is also V ₁ (V _EE ).

Since each electrode is driven as described above, the power consumption at the voltages of V ₅ , V ₄ and V _EE is large in the first period A in FIG. 6, and V ₂ , V ₃ and V _{1 in the} next period B. Power consumption increases at the voltage of. That is, the current flowing through the fifth diagram for an operational amplifier Q1～Q ₄ or the power supply line is 1/2 period greater, 1/2 period smaller. During this time, the operational amplifiers Q1 to Q4 supply the currents flowing in all the driver ICs.

[Problems to be Solved by the Invention]

In the conventional liquid crystal display driving device, the current flowing in the operational amplifier or power supply line of the power supply is 1 /
The two periods are large and the half periods are small, so the power consumption of the operational amplifier is large, it is necessary to use a large capacity operational amplifier, and the fluctuation of the power supply line is also large. There was a problem that the talk became large.

The present invention has been made in view of these problems, and it is possible to reduce the size of an operational amplifier used for a power supply, and to provide a driving device of a liquid crystal display device in which voltage fluctuation is small and crosstalk is reduced. The purpose is to get.

[Means for solving the problem]

A liquid crystal display driving device of the present invention comprises a plurality of resistors connected in series and a plurality of operational amplifiers to which the voltage at the connection point of the resistors is input, and a plurality of output voltage of each operational amplifier is included. In a driving device for a matrix-driving liquid crystal display device, which has a power source for outputting the voltage, the segment electrode and the common electrode are divided into two systems, and two screens are simultaneously displayed, the first device of the liquid crystal display device is provided. Waveforms of respective voltages applied to the segment electrode and the common electrode of the display screen, and respective voltages applied to the electrodes on the same side as the segment electrode and the common electrode of the first surface screen of the second display screen The waveforms are controlled so that they have an inverted relationship with respect to a certain reference potential, and different voltages output from the power source are simultaneously divided into two systems. The so as not to be applied to the people of the electrode are those having a control unit for controlling to apply to each of the electrodes of the display screen.

[Action]

In the liquid crystal display driving device of the present invention, the polarities of the voltages applied to the respective one electrodes divided into the two systems are controlled to be opposite to each other, and the power source including a plurality of resistors and operational amplifiers is used. A plurality of different voltages are output and these voltages are applied so that one voltage is not applied to each electrode at the same time.

〔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, 1 is a control unit for controlling the output voltage of the driver circuit 2 which is made into an IC, and is a voltage applied to one electrode of the first display screen of the liquid crystal display,
The voltage applied to one electrode of the second display screen is controlled to have an inverted relationship, and different voltages output from the power supply are controlled so that one voltage is not simultaneously applied to a plurality of electrodes. It controls so that it may apply to each electrode of each said display screen. Reference numeral 3 denotes an LCD matrix panel of a liquid crystal display that is driven in a simple matrix by the driver circuit 2. The display screen is divided into two and both screens are displayed at the same time.

FIG. 2 is a view showing an electrode structure of the LCD matrix panel 3 described above, and each electrode is divided into two systems. In the figure,
4a is an upper common electrode (scanning electrode) which is a horizontal electrode, 4b is a lower common electrode, and 2Y of these common electrodes 4a and 4b are laterally arranged. 5a is an upper segment electrode (signal electrode) which is a vertical electrode, 5b is a lower segment electrode, and X of these segment electrodes 5a and 5b are arranged vertically.

The voltage applied to each electrode of the liquid crystal display as described above has six kinds of values as shown in FIG. 5, of which four values are alternately selected and applied to generate an AC voltage. I am synthesizing. A normal driver IC for simple matrix driving (driver circuit 2) is formed by CMOS, and when the voltage is switched, a current of several mA is output as several tens of mA per output.
It consumes 0nsec. In the present embodiment, in order to reduce the current consumption, the voltage applied to the upper screen and the lower screen is always inverted by the control unit 1. 3 and 4 show examples of controlling the voltage applied to each electrode.

That is, for example, in the period A in which one screen is created, the voltages applied to the upper common electrode 4a are V ₂ and V _EE , the voltages applied to the upper segment electrode 5a are V ₁ and V ₃ , and the lower common electrode 4b is applied. Applied voltage is V ₁ , V ₅ , lower segment electrode 5b
Voltage applied to the a V _4, V _EE, and controls so that the voltage used all at the same time. Similarly, create the next one screen B
Even during the period, control is performed so that all the voltages shown in FIG. 5 are used. As a result, it is possible to disperse the power sources of the current consumed at one time and smooth the consumed current.
Therefore, the operation of the power supply shown in FIG. 5 can be downsized, and the crosstalk can be reduced by smoothing the voltage fluctuation.

In addition, even in the driving method in which alternating current is applied multiple times within one screen creation period, the current consumption at each voltage is dispersed by controlling the voltages applied to the upper and lower screens so that they are always inverted. Therefore, the consumption current can be smoothed in the same manner.

〔The invention's effect〕

As described above, according to the present invention, the relationship in which the voltage applied to one electrode of the first display screen of the liquid crystal display and the voltage applied to one voltage of the second display screen are inverted In addition to controlling so that different voltages output from the power supply are applied to each electrode of each display screen so that one voltage is not simultaneously applied to a plurality of electrodes, it is used as a power supply. There is an effect that the operational amplifier can be downsized, the voltage fluctuation is reduced, and crosstalk is reduced.

[Brief description 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 an electrode structure of the LCD matrix panel of FIG. 1, and FIG. 3 is a common diagram of FIG. FIG. 4 is a waveform diagram of the voltage applied to the electrodes, FIG. 4 is a waveform diagram of the voltage applied to the segment electrodes of FIG. 2, and 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 the voltage applied to each electrode of the conventional device. 1 …… Control unit 2 …… Driver circuit 3 …… LCD matrix panel 4a …… Upper common electrode 4b …… Lower common electrode 5a …… Upper segment electrode 5b …… Lower segment electrode Q1 to Q4 …… Op Amp

Claims (1)

[Claims] 1. A power supply which comprises a plurality of resistors connected in series and a plurality of operational amplifiers to which the voltage at the connection point of the resistors is input, and which outputs a plurality of voltages including the output voltage of each operational amplifier. In the driving device for a matrix-driven liquid crystal display, wherein each of the segment electrode and the common electrode is divided into two systems to display two screens at the same time, the segment electrode of the first display screen of the liquid crystal display is Reference potential having waveforms of respective voltages applied to the common electrode and waveforms of respective voltages applied to electrodes on the same side as the segment electrode and the common electrode of the first surface screen of the second display screen And the different voltages output from the power source are simultaneously applied to the electrodes divided into two systems. Liquid crystal display driving apparatus characterized by comprising a control unit for controlling to apply to the unusually each of the electrodes of the display screen.