JPH0411281A - Simple matrix system liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce crosstalk by adding input display dot data, column by column, obtaining brightness correction data on each column according to final addition data, and adding this brightness correction data to the input display dot data. CONSTITUTION:An arithmetic means 22 adds the input display dot data DATA to data read out of a storage means 23 and stores the new addition data in the storage means 23 again, and this operation is repeated as to all lines in a display period to store the sum of DATA in respective columns. An arithmetic means 24 converts the sum of DATA in the respective columns into the brightness correction data, which is stored in the storage means 25 and the data is read out simultaneously with the start of the display period to add the brightness correction data to the DATA by an arithmetic means 26. Namely, the gradation of white is increased, column by column, according to the sum of excessive voltages applied to the respective columns to correct a difference in brightness. Consequently, the crosstalk is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a simple matrix type liquid crystal display! all
in between.

[Prior Art] In a simple matrix type liquid crystal panel, a group of signal electrodes extending in the vertical direction and a group of scanning electrodes extending in the horizontal direction are arranged in a matrix, and the intersections of these electrodes are the basic unit of display,
In other words, it becomes a pixel.

A voltage is applied to each scanning electrode one line at a time, and display data for one line is simultaneously applied as a signal voltage to each signal electrode. Therefore, a voltage corresponding to the potential difference between the crossing signal electrode and scanning electrode is applied to each pixel.

Now, if we focus on a certain pixel, when the scanning electrode is active, a signal voltage to be displayed is applied to the signal electrode, but even when the scanning electrode is non-active, the signal electrode is common, so another pixel A signal voltage of is applied.

Therefore, it is affected by the data of pixels belonging to the same column of another line. This is called crosstalk, and is a major factor in reducing contrast.

Conventionally, voltage averaging methods and the like have been known as methods for reducing crosstalk. The voltage averaging method is a method of averaging the voltages applied to non-selected pixels to reduce variations in applied voltages due to painting techniques.

However, with this voltage averaging method, as the number of scanning electrodes increases, a decrease in contrast is unavoidable, making it difficult to achieve a sufficient effect.

Therefore, the present invention aims to further reduce crosstalk.

[Means for Solving the Problems] The present invention includes a first arithmetic means that adds input display tottocheeta for each column, and stores one line of added data output from the first arithmetic means. a first storage means; a second calculation means for converting final addition data sequentially read from the first storage means into luminance correction data;
The brightness correction data output from this second calculation means is
a second storage means for storing lines, a third calculation means for adding the luminance correction data sequentially read from the second storage means to the input display dot data and outputting the result;
The apparatus includes a control means for controlling the operation of each calculation means and storage means based on the input display timing signal.

Then, image reproduction is performed using the display dot data to which the luminance correction data outputted from the third calculation means has been added.

[Function] Crosstalk occurs due to extra voltage being applied because signal electrodes are shared between pixels in the same column. This crosstalk becomes more noticeable when the amount of extra voltage between adjacent columns is significantly different.

For example, if all of the pixel groups in adjacent rows are white (display on), and half of the pixel groups in the rows between them are white (display on) and the other half are black (display off), half of the pixels are white. The extra voltage applied to the displaying pixel is less than the extra voltage applied to the pixels on both sides displaying white, so the pixel becomes darker than the white on both sides.

In the above configuration, input display dot data is added for each column, brightness correction data for each column is obtained based on the final addition data, and this brightness correction data is added to input display dot data. .

That is, depending on the sum of extra voltages applied to each column,
The gradation of white (display on) is increased for each column.

Therefore, the brightness difference due to extra voltage is corrected,
Crosstalk is reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

In the figure, l is a display system including a video memory. Display dot data DATA and display timing signal ST output from this display system l
M is supplied to the crosstalk reduction circuit 2.

This crosstalk reduction interval N2 is configured as shown in FIG.

In the figure, the display timing signal STM is
1. This control means 21 controls the operation of each calculation means and storage means, which will be described later.

Further, the calculation means 22 and the storage means 23 constitute a circuit for calculating the sum of display dot data of each column.

In this case, the calculation means 22 is composed of an adder.

The calculation means 22 calculates the input display dot data DAT.
A and the data read from the storage means 23 are added.

The storage means 23 is constructed with a hanf 7 memory for one line. The added data of each column is sequentially read out in accordance with the display timing and supplied to the calculation means 22, and new addition data supplied from the calculation means 22 is stored again.

This operation is repeated for all lines during the display period,
Finally, the storage means 23 stores the total sum (final addition data) of the display dot data of each column.

The total sum of the display dot data of each column stored in the storage means 23 is stored in the storage means 25 through the calculation means 24 during the flyback period.
is supplied to At the same time, the contents of the storage means 23 are cleared.

The calculation means 24 is constituted by a conversion circuit that converts the sum of display dot data of each column into brightness correction data. In this case, the conversion is made such that the larger the ji8 sum of the display Ft data, the smaller the luminance correction data. The correction level may be optimized in advance or may be set arbitrarily.

The storage means 25 includes a buffer 7 memory for l lines. The storage means 25 stores the luminance correction data of each column converted by the calculation means 24.

The brightness correction data of each column stored in the storage means 25 is stored in the display dot data DA at the same time as the display period starts.
It is read out in synchronization with TA and supplied to the calculation means 26. This calculation means 26 is supplied with display dot data DATA.

This calculation means 26 is composed of an adder, and brightness correction data is added to the display dot data DATA only when the display dot data DATA is display-on data.

Returning to FIG. 1, the display dot data DATA' to which the luminance signal correction data has been added by the calculating means 26 is
The data is supplied as display data to the liquid crystal display device) controller 3. Note that the LCD controller 3 is supplied with a display timing signal STM from the display system 1.

As a result, an image based on the display dot data DATA' is reproduced on a simple matrix type liquid crystal panel (not shown).

In this way, in this example, the display dot data D
A T A is added for each column, and the larger the sum of the display dot data DATA of each column, the smaller the brightness correction data is formed, and this brightness correction data is added to the display dot data D.
Added to AT A. Then, on the simple matrix type liquid crystal panel, mta is reproduced based on the display dot data DATA' to which the luminance correction data has been added.

In other words, in this example, the white gradation is increased and displayed for each column in accordance with the sum of the extra voltage applied to each column of the liquid crystal panel, so the difference in brightness between each column is is corrected.

[Effects of the Invention] As described above, according to the present invention, the white gradation is increased for each column in accordance with the sum of the extra voltages applied to each column of the liquid crystal panel. It is possible to correct the difference in brightness between each column due to the extra voltage applied, and it is possible to reduce crosstalk. According to this invention, even if the number of scanning electrodes increases, the contrast does not deteriorate unlike the voltage averaging method, and is very useful.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of an example of a crosstalk reduction circuit. ! Display system 2 including video memory Crosstalk reduction circuit 3 Liquid crystal display controller 21 Control means 22, 24. 26...Arithmetic means 23.25...Storage means Patent applicant Sharp Corporation

Claims (1)

[Claims] (1) a first calculation means for adding input display dot data for each column; a first storage means for storing one line of added data output from the first calculation means; a second arithmetic means for converting the final addition data sequentially read out from the first storage means into luminance correction data;
a second storage means for storing data for each line; a third calculation means for adding luminance correction data sequentially read from the second storage means to the display dot data and outputting the result; and a third calculation means based on the input display timing signal. and a control means for controlling the operation of each of the calculation means and the storage means, and performs image reproduction using display dot data to which the luminance correction data output from the third calculation means is added. A simple matrix type liquid crystal display device.