JPH0756532A - Liquid crystal panel driving device - Google Patents

Abstract

PURPOSE:To improve the responce speed of the gradation change of the liquid crystal panel. CONSTITUTION:This device is provided with an image memory 11 for storing one frame of inputted digital image data, a ROM 12 as a table memory storing the table of image increase and decrease value data decided by two inputs of image data read by one frame later than this digital image data from the image memory 11, a comparator 13 for comparing these two inputs and judging increase and decrease directions, an adder subtractor 14 for adding or subtracting the digital image data and image increase and decrease value data read from the ROM 12 in accordance with an operation specifying signal from the comparator 13 and a segment driving circuit 6 for displaying and driving the liquid crystal panel based on the output of this adder subtracter 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel drive device for driving and displaying a liquid crystal display panel used in, for example, a liquid crystal television.

[0002]

2. Description of the Related Art A conventional liquid crystal television is generally constructed as shown in FIG. In the figure, 1 is a TV antenna, and the TV broadcast radio wave received by the TV antenna 1 is input to the tuner 2. This tuner 2
Selects the radio wave of the specified channel from the received radio waves,
Converts to an intermediate frequency signal and outputs it to the TV linear circuit 3. This television linear circuit 3 extracts the video signal, the vertical synchronizing signal and the horizontal synchronizing signal from the intermediate frequency signal from the tuner 2, and outputs the video signal to the A / D converter 4 and the vertical synchronizing signal and the horizontal synchronizing signal in the synchronizing control circuit. Output to 5 respectively. The sync control circuit 5 creates various timing signals from the vertical sync signal and the horizontal sync signal, and outputs them to the A / D converter 4, the segment drive circuit 6, and the common drive circuit 7.

The A / D converter 4 converts the video signal into digital data of several bits in synchronization with the sampling clock from the synchronization control circuit 5, and the segment drive circuit 6
Output to. This segment drive circuit 6 creates a gradation signal according to the data from the A / D converter 4 and
Further, a segment electrode drive signal is created based on this gradation signal to drive the display of the segment electrodes of the dot matrix type liquid crystal panel 8. In addition, the common drive circuit 7
Reproduces the common electrode drive signal in accordance with the timing signal from the synchronization control circuit 5 and sequentially drives the common electrodes of the liquid crystal panel 8 selectively.

[0004]

The liquid crystal panel 8 is driven based on the video signal received as described above. Since the liquid crystal panel 8 operates by the cumulative response effect as shown in FIG. It has the property of being slow. That is, FIG. 5 shows the relationship between the liquid crystal drive voltage composite waveform and the light transmittance of the liquid crystal panel 8 when the gradation is “7” and “0”. On the other hand, in the above-mentioned conventional liquid crystal panel driving method, as shown in FIG. 5, the grayscale signal corresponding to the video signal is simply created and the liquid crystal panel 8 is driven. There was a problem that the response characteristics could not be improved and it was not possible to deal with fast moving images.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal panel drive device capable of improving the response speed of gradation change of a liquid crystal panel.

[0006]

That is, according to the present invention, in a liquid crystal panel drive device for displaying an image using a liquid crystal panel which responds cumulatively, the input digital image data is set to 1.
An image memory for storing frames, a table memory for storing a table of image increase / decrease value data determined by two inputs of the digital image data and image data read from the image memory with a delay of one frame, and the two inputs. A comparator for comparing and judging the increase / decrease direction, an adder / subtractor for adding or subtracting the digital image data and the image increase / decrease value data read from the table memory according to the output of the comparator, and an output of the adder / subtractor Drive means for driving the display of the liquid crystal panel based on the above is provided.

[0007]

With the above-described structure, when the image data changes, the optimum increase / decrease value stored in advance is read according to the direction and degree of the change, and the image is changed in accordance with the increase / decrease direction. The data and the increase / decrease value are added or subtracted to obtain the emphasized image data, and the liquid crystal panel is driven by this emphasized image data, and the rise or fall of the light transmittance is steep in a necessary and sufficient range. Becomes As a result, it is possible to increase the response speed of the liquid crystal panel and quickly follow an image that changes abruptly, while realizing the emphasis calculation with a memory having a small storage capacity.

The "frame" referred to in the present specification means that all picture elements which form one screen are scanned, and for example, one picture element which forms one screen for each field of a television signal. In a display device that scans and displays all in one way, one field of a television signal and one frame referred to in the present application are considered to be equal and do not necessarily match a "frame" generally used in a television signal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a liquid crystal television will be described below with reference to the drawings. FIG. 1 shows a partial circuit configuration thereof. Since the circuit configuration of the entire liquid crystal television is basically the same as that described in FIG. 4, the same reference numerals are used for the same portions, and the illustration and description thereof are omitted. To do.

However, the image data output from the A / D converter 4 is sent to each of the image memory 11, the ROM 12, the comparator 13 and the adder / subtractor 14. The image memory 11 is a dual-port memory capable of storing image data for one frame, operates according to the memory address and write / read command given from the synchronous control circuit 5, and operates the A / D converter 4
Image data of, for example, 3 bits sent from the CPU is sequentially stored, and after one frame, sequentially output to the address terminal H of the ROM 12 and the terminal V of the comparator 13.

The address terminal L of the ROM 12 is A /
The image data output from the D converter 4 is directly input. The ROM 12 pre-stores increase / decrease value data indicating the difference between the image data of this time and the image data of the previous frame in the form of a table, and the increase / decrease value corresponding to the address selected by the address terminals H and L. Data is adder / subtractor 14
Read to.

An A / D converter is connected to the terminal U of the comparator 13.
The image data output from 4 is directly input. The comparator 13 determines the increase / decrease direction by comparing the image data of this time with the image data of one frame before, and sends the determination result to the adder / subtractor 14 as a calculation designation signal.

The adder / subtractor 14 adds or subtracts the image data directly sent from the A / D converter 4 and the increase / decrease value data sent from the ROM 12 according to the operation command signal from the comparator 13 Image data in which the degree of change in the tone is emphasized is created, and the obtained image data is supplied to the segment drive circuit 6 and displayed on the liquid crystal panel 8.

Next, the operation of the above embodiment will be described. A / D
It is assumed that the gradation to be sent to the segment drive circuit 6 when the image data output from the converter 4 changes from the previous gradation to the current gradation has a content as shown in FIG. 2, for example.

At this time, if a value obtained by subtracting the current gradation from the gradation to be output is stored as the contents of the table of the ROM 12, it indicates how much the output of the ROM 12 should be increased or decreased from the current gradation. It becomes data.

FIG. 3 shows a table of increase / decrease value data stored in the ROM 12 with plus and minus signs. Actually, the increase / decrease value data of only the numerical value with the sign removed is read out and added / subtracted. It will be sent to 14.

Further, the comparator 13 compares the gradation (U) of this time with the gradation (V) of the previous time, and if the gradation of this time is greater than or equal to the gradation of the previous time, "U≥V". Is a calculation specifying signal indicating addition, and if the current gradation is smaller than the previous gradation, a calculation specifying signal indicating subtraction is added if "U <V"
Shall be sent to 14.

However, the adder / subtractor 14 adds or subtracts the increase / decrease value data from the ROM 12 as an addend or a subtraction based on the image data of this time sent from the adder / subtractor 14 according to the operation designation signal from the comparator 13. And outputs the calculation result to the segment drive circuit 6. At this time, the image data output from the adder / subtractor 14 emphasizes the degree of gradation change as shown in FIG. Therefore, the rise or fall of the light transmittance of the liquid crystal panel 8 becomes steep, and the response speed of the liquid crystal panel 8 that makes a cumulative response can be increased, and it is possible to quickly follow an image that changes rapidly. Becomes

If the table shown in FIG. 2 is directly stored in the ROM 12 and the emphasized image data is read out and output to the segment drive circuit 6 of the next stage, one image data stored in the ROM 12 is stored. Has 8 gradations, the required data amount is 3 bits.

However, as shown in FIG. 3, in this embodiment, the increase / decrease value data for the gradation of the image data of this time is R
Because it is stored in OM12, it is stored in ROM12 1
Each increase / decrease value data has 4 gradations, and the required data amount is 2 bits. In this way, it is possible to significantly reduce the amount of data to be stored in the ROM 12 and realize the circuit with a ROM having a small storage capacity.

[0021]

As described above, according to the present invention, when the image data changes, the optimum increase / decrease value stored in advance is read according to the direction and degree of the change, and the optimum increase / decrease value is read in the increase / decrease direction. The image data and the increase / decrease value are added or subtracted accordingly to obtain the emphasized image data, and the liquid crystal panel is driven by the emphasized image data, and the rise or fall of the light transmittance thereof is necessary and sufficient. It becomes steep in the range. As a result, a liquid crystal panel drive device capable of enhancing the response speed of the liquid crystal panel and quickly following an image that changes abruptly while realizing the emphasis calculation with a memory having a small storage capacity. Can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing a table of image data to be output according to the embodiment.

FIG. 3 is a diagram showing an increase / decrease value data table stored in a ROM shown in FIG.

FIG. 4 is a block diagram showing a circuit configuration of the entire conventional liquid crystal television.

5 is a diagram showing a display drive waveform corresponding to the conversion data of FIG.

[Explanation of symbols]

1 ... TV antenna, 2 ... Tuner, 3 ... TV linear circuit, 4 ... A / D converter, 5 ... Synchronous control circuit, 6 ... Segment drive circuit, 7 ... Common drive circuit, 8 ... Liquid crystal panel, 11 ... Image memory , 12 ... ROM, 13 ... comparator, 14 ... adder / subtractor.

Claims (1)

[Claims] 1. A liquid crystal panel driving device for displaying an image using a liquid crystal panel, comprising: an image memory for storing input digital image data for one frame; and reading the digital image data and the image memory with a delay of one frame. From the digital image data and the table memory, a table memory storing a table of image increase / decrease value data determined by two inputs of image data, a comparator for comparing the two inputs to determine an increase / decrease direction, A liquid crystal panel comprising: an adder / subtractor for adding or subtracting the read image increase / decrease value data according to the output of the comparator; and a drive unit for driving the display of the liquid crystal panel based on the output of the adder / subtractor. Drive.