JPH0741586U - Display drive - Google Patents

Abstract

(57) [Summary] [Object] To realize a display drive device capable of driving a liquid crystal display device by artificially setting the bias potential during liquid crystal drive to at least the number of liquid crystal drive bias power supply terminals of the drive IC. A display driving device 10 includes a power supply circuit A11 and a power supply circuit B12, each of which generates a plurality of sets of liquid crystal driving bias voltages, and a set of liquid crystal output from either the power supply circuit A11 or the power supply circuit B12. A liquid crystal drive output of the scan electrode drive circuit 17 is provided with a multiplexer 13 that outputs a drive bias potential, a comparator A14 that determines whether or not the drive power supply potential is stable, a comparator B15, and an EX-OR circuit 16. The input to the bias power supply terminal is synchronized with the frame signal from the control unit 22 and switched by the multiplexer 13 to artificially increase the liquid crystal drive bias potential.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a display driving device, and more particularly, to a display driving device that drives a matrix type liquid crystal display panel.

[0002]

[Prior art]

 LCD TV screen displays require high-performance, high-quality display functions such as high resolution, high gradation, high-speed response, and high contrast. As the display method, TN (Twiste d Nematic) type, STN (Supertwisted Nematic) type, etc., as well as ferroelectric type and anti-ferroelectric type are used, and the drive method is an active matrix using TFT (Thin Film Transistor). Drive and simple matrix drive are adopted.

A display driving device that drives the liquid crystal display device basically includes a control unit that generates timings necessary for driving such as video data and a frame signal, and a power supply unit that generates and supplies a video driving potential. , A drive unit for supplying a drive waveform to the liquid crystal panel by using the timing signal from the control unit, the video data and the liquid crystal drive potential supplied by the power supply unit.

[0004]

[Problems to be solved by the device]

 However, since the liquid crystal driving potential is connected to the driving unit and the liquid crystal driving bias power source terminal of the driving IC on a one-to-one basis, the number of liquid crystal driving bias potentials is limited. For example, in the simple matrix drive system such as the TN type and the STN type, four types of liquid crystal drive bias potentials are usually commercially available.

However, in a liquid crystal display device such as an antiferroelectric liquid crystal in which a writing threshold voltage exists at positive and negative voltages and a voltage having a polarity opposite to that of the writing voltage is applied before writing. Liquid crystal driving bias potentials of 5 to 8 are required. In contrast to such types of devices that require a large number of bias potentials, applying a drive device for each type of required bias potential cannot produce the effect of mass production of the drive device and is expensive. There was a problem that it would end up.

Therefore, an object of the present invention is to provide a display driving device capable of driving a liquid crystal display device by making the bias potential during liquid crystal driving pseudo above the number of liquid crystal driving bias power supply terminals of the driving IC. To do.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the invention according to claim 1 is a display drive device for supplying a power supply potential to a bias power supply terminal of a liquid crystal display device, wherein a plurality of power supply circuits each generate a plurality of sets of liquid crystal drive bias potentials. And a plurality of liquid crystal driving bias potentials output from the power supply circuit by selecting one of the power supply circuits of the power supply means to the bias power supply terminal of the liquid crystal display device. A selection means for outputting and a means for switching the selection means to supply the bias voltage for liquid crystal driving outputted from another power supply circuit to the bias power supply terminal of the liquid crystal display device.

[0008]

[Action]

 In the present invention, the power supply means generates a plurality of sets of liquid crystal driving bias potentials from each power supply circuit, and the input to the bias power supply terminal of the liquid crystal display device is switched by the selection means at a predetermined timing and output.

Therefore, the liquid crystal drive potential can be increased in a pseudo manner, and even a liquid crystal drive IC having a small liquid crystal drive bias potential can supply a liquid crystal drive waveform having many potential levels.

[0010]

EXAMPLES Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a display driving device of the present invention.

First, the configuration will be described. FIG. 1 is an overall configuration diagram of a display drive device.

In FIG. 1, the display drive device 10 includes a power supply circuit A 11, a power supply circuit B 12, a multiplexer 13, a comparator A 14, a comparator B 15, an EX-OR circuit 16, a scan electrode drive circuit 17, a shift register 18, and a latch. It is composed of a circuit A19, a latch circuit B20, a decoder 21 and a controller 22.

Further, in a liquid crystal display panel (not shown) from which the output of the decoder 21 is output, a plurality of scanning electrodes and a plurality of signal electrodes are arranged so as to face each other with a liquid crystal layer in between, and arranged in a matrix. A signal electrode drive circuit (not shown) that drives the signal electrodes and a scan electrode drive circuit 17 that drives the scan electrodes are provided.

The power supply circuit A 11 generates four liquid crystal drive bias potentials and supplies them to the multiplexer 13 and the comparator A 14, respectively. Further, the power supply circuit B12 generates four liquid crystal drive bias potentials, and supplies them to the multiplexer 13 and the comparator B15, respectively.

The power supply circuit A 11 and the power supply circuit B 12 generate and supply liquid crystal driving bias potentials equal to or larger than the number of bias power supply terminals to the scan electrode driving circuit 17 for driving the liquid crystal display device, and in the present embodiment. The power supply circuit A11 and the power supply circuit B12 supply four separate liquid crystal drive potentials. The liquid crystal drive bias potentials generated in the power supply circuit A11 and the power supply circuit B12 are output to the multiplexer 13, respectively.

Based on the control signal from the control unit 22, the multiplexer 13 switches so as to output either one of the power supply circuit A 11 and the power supply circuit B 12 to the scan electrode drive circuit 17. The multiplexer 13 is composed of a plurality of analog switches, and its on-resistance is sufficiently low.

The comparator A14 and the comparator B15 are connected to the power supply circuit A11 and the power supply circuit B12, respectively, and determine whether or not the drive power supply potential switched by the multiplexer 13 is stable, and the comparison result is EX-. The OR circuit 16 performs EX-OR and outputs the result to the scan electrode drive circuit 17. Here, a signal for stopping the display is applied to the scan electrode drive circuit 17 during the transient period when the drive power supply potential is not stable.

The scan electrode drive circuit 17 is composed of a driver circuit, a scan shift register, and the like. The shift register is provided for each scan line according to the scan shift clock signal CPV and the scan side drive signal φV from the control unit 22. Pixel voltages S1 to Sm supplied to the data line DL are supplied to the decoder 21 which will be described later while sequentially supplying predetermined scanning signals G1 to Gn.

The data transfer clock CPH and the data DATA are input from the control unit 22 to the data side shift register 18, and the shift register 18 shifts the data DATA by the data transfer clock CPH and outputs the data DATA to the latch circuit A 19.

The latch circuit A 19 fetches and latches the output data from the shift register 18 according to the latch signal L 1 from the control unit 22.

The latch circuit B 20 takes in and latches the latched data from the latch circuit A 19 according to the latch signal L 2 from the control unit 22.

The control unit 22 outputs a video signal, a timing signal, and a control signal to each unit based on the synchronization signal to control each unit and the entire apparatus.

The decoder 21 determines the pixel voltages S1 to Sm based on the data output from the latch circuit B20 and the frame signal DF, and supplies the pixel voltages S1 to Sm to the data line DL.

Next, the operation of this embodiment will be described.

In the power supply circuit A11 and the power supply circuit B12, four separate liquid crystal driving bias potentials are supplied to the multiplexer 13, the comparator A14, or the comparator B15, respectively.

That is, the power supply circuit A 11 and the power supply circuit B 12 generate and supply liquid crystal driving bias potentials equal to or larger than the number of bias power supply terminals of the scan electrode driving circuit 17 for driving the liquid crystal display device.

In the multiplexer 13, a set of liquid crystal drive bias potentials from the power supply circuit A 11 or the power supply circuit B 12 is supplied to the liquid crystal drive bias power supply terminals of the scan electrode drive circuit 17 in synchronization with the frame signal F from the control unit 22. Select and switch to. Therefore, the scan electrode drive circuit 17 is supplied with four liquid crystal drive bias potentials from the power supply circuit A11 and four liquid crystal drive bias potentials from the power supply circuit B12 switched for each frame. That is, eight liquid crystal driving bias potentials are output from the scan electrode driving circuit 17.

The liquid crystal drive potentials generated in the power supply circuit A11 and the power supply circuit B12 are output to the comparator A14 and the comparator B15, and in the comparators A14 and B15, the drive power supply potential switched by the multiplexer 13 is changed. It is determined whether or not it is stable, and a signal for stopping the display is given to the scan electrode drive circuit 17 during the unstable period.

As described above, the display driving apparatus 10 of the present embodiment selects the power supply circuit A11 and the power supply circuit B12 and one of the power supply circuit A11 and the power supply circuit B12 to drive a plurality of sets of liquid crystal. A multiplexer 13 that outputs a bias potential, a comparator A14 that determines whether or not the drive power source potential is stable, a comparator B15, and an EX-OR circuit 16 are provided, and a plurality of sets of liquid crystal drive bias potentials are generated. Since the input to the liquid crystal drive output bias power supply terminal of the scan electrode drive circuit 17 is switched by the multiplexer 13 in synchronism with the frame signal from the controller 22, the liquid crystal drive potential is artificially increased. A liquid crystal drive IC having only four bias potentials can generate a liquid crystal drive waveform having voltage levels of 5 potentials and 6 potentials. It is possible to exert an effect on a liquid crystal display device that requires a large number of liquid crystal driving voltages, such as an antiferroelectric liquid crystal.

[0031]

[Effect of device]

 According to the present invention, a power supply means having a plurality of power supply circuits for generating a plurality of sets of liquid crystal drive bias potentials and a selection for selecting the plurality of sets of liquid crystal drive potentials and outputting them to a bias power supply terminal of a liquid crystal display device. Since it is provided with the means, the liquid crystal drive potential can be increased in a pseudo manner, and the liquid crystal drive waveform having many potential levels can be generated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a display driving device according to the present invention.

[Explanation of symbols]

 10 display drive device 11 power supply circuit A 12 power supply circuit B 13 multiplexer 14 comparator A 15 comparator B 16 EX-OR circuit 17 scan electrode drive circuit 22 control unit

Claims (1)

[Scope of utility model registration request] 1. A display drive device for supplying a power supply potential to a bias power supply terminal of a liquid crystal display device, and a power supply means each having a plurality of power supply circuits for generating a plurality of sets of liquid crystal drive bias potentials; The selecting means is switched between selecting means for selecting one of the power supply circuits of the supplying means and outputting a plurality of liquid crystal driving bias potentials output from the power supply circuit to the bias power supply terminal of the liquid crystal display device. And a means for supplying a bias potential for driving a liquid crystal output from another power supply circuit to the bias power supply terminal of the liquid crystal display device.