JPH0468391A - Simple matrix drive type color liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce crosstalk without any decrease in contrast by increasing gradations of white, column by column, according to the total of excessive voltages applied to the respective columns of a liquid crystal panel. CONSTITUTION:Display dot data DR, DG, and DB of red, green, and blue and a display timing signal STM which are outputted from a display system 1 are supplied to a crosstalk reducing circuit 200. The crosstalk reducing circuit 200 is constituted differently according to a difference of an array of filters of red(R), green(G), and blue(B) constituting one pixel of a color liquid crystal panel. Gradations of white (display ON) are increased, column by column, according to the total of excessive voltages applied to respective columns. Consequently, a difference in brightness due to the excessive voltages is corrected without any decrease in contrast to reduce the crosstalk.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a simple matrix drive type color liquid crystal display device.

[Prior Art] In a simple matrix drive 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 units of display, that is, pixels. Become.

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 pole 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 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 that attempts to average the voltages applied to non-selected pixels to reduce variations in the applied voltages depending on the pixels.

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

Therefore, it is an object of the present invention to reduce crosstalk without reducing contrast.

[Means for Solving the Problems] The present invention includes a first calculation means for adding input display dot data of each color of red, green, and blue for each column, and an output from the first calculation means. A first storage means for storing one line of added data for each color, and a first storage means for storing one line of added data for each color, and corrects the brightness of each color by taking into account the visual brightness difference between each color. a second calculation means for converting into data; a second storage means for storing one line of brightness correction data of each color output from the second calculation means; and a brightness of each color read out sequentially from the second storage means. A third calculation means for adding the correction data to each display dot data and outputting the result, and a control means for controlling the operation of each calculation means and storage means based on the input display timing signal, Image reproduction is performed using display dot data of each color added with luminance correction data output from the calculation means.

The present invention also provides a fourth calculation means for converting input display dot data of each color of red, green, and blue into brightness data in consideration of the visual brightness difference between each color, and an output from the fourth calculation means. a first calculation means for adding the luminance data for each column;
A first storage means for storing data for each line, a second calculation means for converting the final addition data sequentially read from the first storage means into brightness correction data, and a second calculation means for converting the brightness correction data outputted from the second calculation means. a second storage means for storing one line; a third calculation means for adding and outputting the luminance correction data sequentially read from the second storage means to the display dot data of each color; and an input display timing signal. It is equipped with a control means for controlling the operation of each calculation means and storage means based on the above, and performs image reproduction using display dot data of each color to which the luminance correction data outputted from the third calculation means is added. be.

[Effect] Cochrotalk occurs when extra voltage is applied because pixels in the same column share a signal electrode. 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), 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 pixel groups are white (display on). The extra voltage applied to the pixel that is displaying is smaller than the extra voltage that is applied to the pixels on both sides displaying white, so the pixel is 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 the 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 difference in brightness due to the extra voltage is corrected without reducing contrast, and crosstalk is reduced.

[Execution N] First, a monochrome liquid crystal display device using a simple matrix drive method as shown in FIG. 7 will be described.

In the figure, 1 is a display system including a video memory. The display dot data DATA and display timing signal STM output from the display system 1 are supplied to a crosstalk reduction circuit 2.

This crosstalk reduction circuit 2 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 has a buffer memory for one line, and the added data of each column is sequentially read out in accordance with the 0 display timing and supplied to the calculation means 22, and the data is also supplied from the calculation means 22. New addition data 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.
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 performed so that the larger the total sum of display dot data, the smaller the luminance correction data. The correction level may be optimized in advance, or may be set arbitrarily. The storage means 25 is constructed with a buffer memory for one line. 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 only when the display dot data DATA is display-on data, the display dot
The luminance correction data is added to the image data DATA.

Returning to FIG. 7, the display dot data DATA' to which the luminance correction data has been added by the calculating means 26 is supplied to the LCD (liquid crystal display device) controller 3 as display data. Note that the LCD controller 3 includes a display system 1.
A display timing signal STM is supplied from.

As a result, a simple matrix drive type liquid crystal panel (
(not shown), a black and white image is reproduced using the display dot data DATA'.

In the example in FIG. 7, the display dot data DATA is added for each column, and the larger the sum of the display dot data DATA in each column is, the smaller the brightness correction data is formed, and this brightness correction data is added to the display dot data DATA. be done. Then, a black and white image is reproduced on the liquid crystal panel based on the display dot data DATA' to which the luminance correction data has been added.

In other words, in the example of FIG. 7, the extra voltage applied to each column of the liquid crystal panel is 1! Since the white gradation is increased and displayed in each column according to the sum, the difference in brightness between each column can be corrected without reducing the contrast, and crosstalk can be reduced.

Next, an embodiment of the present invention will be described with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 7 are designated by the same reference numerals.

At the same port, the red, green, and
The blue display dot data DR, DG, DB and the display timing signal STM are each sent to the crosstalk reduction circuit 2.
00.

The crosstalk reduction circuit 200 is connected to one of the color liquid crystal panels.
The arrangement of the red (R), green (G), and blue (B) filters that make up each pixel is different, resulting in an interesting configuration.

As shown in FIG. 2A, when a pixel is composed of pixels arranged in the horizontal direction and the RGB filter is arranged in a vertical stripe arrangement, it is necessary to calculate an extra voltage for each pixel. It is configured as shown in Figure 3.

On the other hand, as shown in Figure 2B, when pixels are arranged vertically to form a pixel and the RGB filter is arranged in a horizontal stripe arrangement, it is necessary to calculate extra voltage for each pixel. .

It is constructed as shown in FIG.

First, the crosstalk reduction circuit 200 shown in FIG. 3 will be explained. In FIG. 3, portions corresponding to those in FIG. 8 are designated by the same reference numerals, or are designated by R to B.

In the figure, display dot data DR1DG, D
B are signal processing circuits 201R1201G and 20, respectively.
1B. Although detailed explanation is omitted, the calculation means 22R to calculation means 26R2 of the signal processing circuit 201R, the calculation means 22G to calculation means 26G of the signal processing circuit 201G, and the calculation means 22B to calculation means 26B of the signal processing circuit 201B.
are controlled by the control means 21, and operate in the same manner as the calculation means 22 to 26 in the example of FIG. Therefore, red, green, and blue display dot data DR', DG' with luminance correction data added are obtained from each of them.
, DB' are output.

Note that in the calculation means 24R, 124G, and 24B, the final addition data for each column for each color of red, green, and blue is converted into brightness correction data, taking into consideration the visual brightness difference between each color. converted.

The display dot data DR', DG', DB' of each color, which is the sum of the luminance correction data output from the signal processing circuits 201R, 1201G, and 201B, is calculated by the calculation means 28R, respectively.
Supplied to 128G and 28B.

These calculating means 28R128G and 28B are each supplied with a control signal SC from the display system 1 (not shown in FIG. 3) for controlling whether or not to perform reverse gamma correction.

By the way, the emission characteristics of a cathode ray tube are shown by the broken line a in Figure 5A.
Therefore, so-called gamma correction may be applied to the video signal with the characteristics shown by the solid line in the figure. The above-mentioned inverse gamma correction is shown by the solid line C in FIG. 5B.
This process corrects the display dot data using the characteristics of the gamma correction.

The calculation means 28R is configured as shown in FIG. 6, for example.

In the figure, display dot data DR' output from the signal processing circuit 201R is supplied to the A side of the selector 282 via the table 281, and is also directly supplied to the selector 282.
It is supplied to the B side of 82.

The table 281 is composed of RAM, ROM, etc., and is supplied with display dot data DR' as address data.
The reverse gamma-corrected data DR'' is read out.

The selection in the selector 282 is controlled based on the control signal SC. For example, when the control signal SC indicates that inverse gamma correction is to be performed, the display dot data that has been inversely gamma corrected is input to the A side. DR'' is selected and output, and on the other hand, when the control signal SC indicates that no inverse gamma correction is to be performed, display dot data DR' input to the B side and not subjected to inverse gamma correction is selected and output.

Although the explanation is omitted, the calculation means 28G and 28B are also configured in the same manner as the calculation means 28R described above.

Next, the crosstalk reduction circuit 200 shown in FIG. 4 will be explained. In FIG. 4, parts corresponding to those in FIG. 8 and FIG. 3 are designated by the same reference numerals or are further designated by R to B.

In the figure, display dot data DR1DG, D
B is supplied to the calculation means 27 and converted into luminance data. Conversion into luminance data is performed, for example, as follows, taking into consideration the visual luminance difference between each color.

Brightness data = 0. 30R+0. 59G+〇, the luminance data output from the IIB calculation means 27 is sent to the signal processing circuit 20.
2. Although the explanation will be omitted, the operation of this signal processing circuit 202 is controlled by the control means 21, and operates in the same manner as the shingle means 22 to the calculation means 25 in the eighth section example. Therefore, 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 read out in synchronization with the display dot data DR, DG, DB at the same time as the display period starts, and is supplied to the calculation means 26R126G, 26B. .

Display dot data DR, DG, and DB of each color are supplied to the calculation means 26R, 126G, and 26B, respectively. The operation of these calculating means 26R126G, 26B is controlled by the control means 21, and the calculating means 26 in the example in FIG.
works the same way.

Therefore, the calculation means 26R, 126G, and 26B output the display dot data D to which the luminance correction data has been added.
R', DG', and DB' are output.

The display dot data DR', DG'DB' of each color output from the calculation means 26R126G, 26B are supplied to the calculation means 28R228G, 28B, respectively.

These calculating means 28R128G, 28B are configured as explained in the example of FIG.
Accordingly, display dot data DR', DG', DB' to which luminance correction data has been added or display dot data DR'', DG'', DB'' to which reverse gamma correction has been further performed is output.

Returning to FIG. 1, the red, green, and blue display dot data DR'DG' output from the crosstalk reduction circuit 200
DB′ or DR″, DG″DB″ is supplied to the LCD controller 3 as display data.
The controller 3 is supplied with a display timing signal STM from the display system 1 .

As a result, a color image based on the single display dot data DR', DG', DB' or DR'', DG'', DB'' is reproduced on the simple matrix drive type color liquid crystal panel.

In this way, also in this example, the brightness is increased and displayed for each column according to the sum of the extra voltage applied to each column of the liquid crystal panel, so the same effect as in the example in FIG. 7 can be obtained. Obtainable.

Further, according to this example, the crosstalk reduction circuit 200 can output the display dot data DR", DG", DB" that has been reverse gamma corrected by the control signal SC. Therefore, the display dot data DR, DG , DB is gamma-corrected data, image reproducibility can be further improved by inverse gamma correction.

Incidentally, although not mentioned above, calculation means for performing reverse gamma correction can be added to the black and white liquid crystal display device shown in the example of FIG.

[Effects of the Invention] As explained above, according to the present invention, the white gradation is increased for each column in accordance with the sum of the extra voltage 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. Even if the number of scanning electrodes increases, unlike the voltage averaging method, the contrast does not deteriorate, making this method very useful.

Furthermore, by selectively providing a reverse gamma correction function, image reproducibility can be improved when display dot data (video signal) is gamma-corrected data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of the arrangement of RGB filters in a color liquid crystal panel, FIGS. 3 and 4 are block diagrams of a crosstalk reduction circuit, and FIG. The figure is an explanatory diagram of reverse gamma correction, Figure 6 is a block diagram of the calculation means for reverse gamma correction, Figure 7 is a diagram of a black and white liquid crystal display device, and Figure 8 is a diagram of its crosstalk reduction circuit. be. 1. Display system including video memory 2.200 Crosstalk reduction circuit 3 Liquid crystal display device controller 21 Control means 22 22R to 22B, 24.24R to 24B 26.2
6R to 26B, 28R to 28B calculation means 23 23R to 23B, 25.25R to 25B storage means 201R to 201B, 202 ・Signal processing circuit

Claims (3)

[Claims] (1) A first calculation means that adds the input display dot data of each color of red, green, and blue for each column, and adds one line of each color of addition data output from the first calculation means. and a second operation for converting the final addition data of each color sequentially read from the first storage means into brightness correction data of each color in consideration of the visual brightness difference of each color. means, second storage means for storing one line of brightness correction data of each color outputted from the second calculation means, and displaying the brightness correction data of each color sequentially read from the second storage means, respectively. The third calculation means includes a third calculation means that adds to the dot data and outputs the result, and a control means that controls the operation of each of the calculation means and storage means based on the input display timing signal, and the third calculation means A simple matrix drive type color liquid crystal display device that reproduces an image using display dot data of each color added with luminance correction data output from a color liquid crystal display device. (2) a fourth calculation means that converts the input display dot data of each color of red, green, and blue into brightness data taking into consideration the visual brightness difference of each color; and a first calculation means for adding luminance data for each column; a first storage means for storing one line of added data outputted from the first calculation means; a second calculation means for converting the read final addition data into brightness correction data; and a second calculation means that converts the brightness correction data output from the second calculation means into one
a second storage means for storing lines; a third calculation means for adding and outputting the luminance correction data sequentially read from the second storage means to the display dot data of each color; and input display timing. and control means for controlling the operations of each of the calculation means and the storage means based on the signal, and reproduces an image using display dot data of each color added with the luminance correction data output from the third calculation means. A color liquid crystal display device using a simple matrix drive method. (3) A simple matrix drive type color liquid crystal display device according to claim 1 or 2, wherein means for performing inverse gamma correction on the display dot data of each color is provided after the third calculation means.