JPS61256386A - Liquid crystal display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device that displays images using a liquid crystal display plate and is suitable for, for example, a liquid crystal television receiver.

[Summary of the invention]

This invention provides a liquid crystal display device having a liquid crystal matrix panel as a display surface, in which brightness unevenness information based on thickness unevenness of the liquid crystal plate is recorded in advance in a memory, and images supplied to the liquid crystal matrix 9 panels are provided. The signal is configured to be successively level modulated by data read from the memory. Therefore, the liquid crystal matrix 7
Even if there is uneven brightness in the G channel, an image with uniform brightness can be displayed.

[Conventional technology]

Compared to other types of display devices, liquid crystal display devices have the advantage of being lightweight, making it easy to make them thinner and save power, so they are used not only as digital display devices but also as analog image display devices. For example, it has come to be used in television receivers, etc.

Figure 2 is a block diagram of the drive circuit for the liquid crystal matrix panel (liquid crystal display board with scanning electrodes), in which 1 is an amplifier for the video signal, and 2 is for forming color signals of three primary colors from the video signal. The demodulation circuit, 3, is a TN liquid crystal (twisted nematic), which is sandwiched between two deflection plates from below, and is provided with color filters, scanning electrodes, etc. inside.IJ rack type liquid crystal display board, 4 , 5 indicate an X-shift register and a Y-shift register that supply signals for scanning the liquid crystal display panel 3 in the horizontal and vertical directions, respectively, and their outputs are sent to a large number of scanning electrodes on the liquid crystal display panel 3. It is connected.

The liquid crystal display board 3 is configured so that, for example, when a voltage is applied to a specific liquid crystal cell, the amount of light transmitted through that liquid crystal cell via a color filter changes. This figure shows an example of the relationship between the ratio and the applied voltage.

As is well known, the driving circuit of such a liquid crystal television scans the liquid crystal display panel 3 by supplying a clock signal of a predetermined period and horizontal and vertical synchronizing pulses to the X, Y shift register 4.5. When a video signal consisting of three primary colors is applied to the liquid crystal cell while scanning, the light transmittance of the liquid crystal cell changes approximately in proportion to the applied voltage between the applied voltages E1 and E2, so that a Brevi color image is displayed on the liquid crystal display board 3. can be displayed.

[Problem that the invention seeks to solve]

By the way, even if the LCD TV is small,
When increasing the size of the screen, there is a problem that unless the thickness of the liquid crystal is uniform across the entire screen, uneven brightness will occur and the image quality will deteriorate.

Therefore, it is required that the liquid crystal display board 3 has a uniform thickness, but as the screen size increases, it becomes difficult to manufacture a liquid crystal display board 3 with a uniform thickness, which is a factor in increasing costs. It becomes.

This invention was made to solve this problem, and even when using a liquid crystal display board with uneven brightness due to non-uniform thickness of the liquid crystal display board, the same brightness can be achieved on the entire screen. The present invention provides a liquid crystal display device with high brightness.

[Means for solving problems]

In an image display device using a liquid crystal matrix panel whose light transmittance changes depending on the level of an applied signal, a memory IJ (ROM) storing local brightness information of the liquid crystal matrix/Q panel is provided, The video signal supplied to the liquid crystal matrix channel is configured to be level-modulated by data read from the memory (ROM) using a scanning signal as an address signal.

[For production]

The local brightness of the liquid crystal matrix panel is measured in each predetermined area using, for example, a photoelectric conversion element, and data regarding the brightness is recorded at a predetermined address in memory via a computer, and the video signal is recorded. When input, the brightness information data stored in the memory is read out sequentially using the scanning signal as an address code, and this data is used to display the LCD matrix. controls the amplitude of the video signal applied to the channel.

Therefore, the brightness of the liquid crystal display is uneven.
Even when using 7 channels, images with uniform brightness can be displayed.

〔Example〕

FIG. 1 is a block diagram showing an embodiment in which the liquid crystal display device of the present invention is applied to a television receiver, and the same parts as in FIG. 2 are designated by the same symbols.

The part 100 surrounded by a dashed line indicates a correction signal generation circuit section, which includes a first frequency divider circuit 11 that divides the frequency of the horizontal clock signal, and a second frequency divider circuit 12 that divides the frequency of the vertical clock signal. , counter ia for forming address signals
, 14. Memory for recording brightness information as data (R
OM) 15.

It is composed of a D/A converter 16. Further, a filter 17 is provided as required.

A portion 20 surrounded by a two-dot chain line is a detection unit for storing brightness information as data in the memory 15, and a charging conversion element 2 that detects the brightness of a predetermined area of the liquid crystal display board 3.
1. Amplifier 22. It includes an A/D converter 23, a microprocessor 24, an input device 25, and the like.

For example, when a white level video signal is supplied to the liquid crystal display board 3, the detection unit 20 moves the liquid crystal display board 3 into a predetermined area s.
i, s2. s3...'+Brightness unevenness information is detected for each Sn and inputted to the memory 15 as brightness information.

That is, standard data indicating the brightness when a video signal VS of a prescribed brightness level is input is input into the microprocessor 24, and the photoelectric conversion element 21 is controlled to adjust the brightness of this part, for example, in the area S1 of the liquid crystal display board 3. Amplifier 22. The data is taken into the microprocessor 24 via the A/D converter 23 and compared with the reference data. Then, the D/A converter 16
A control signal is supplied to increase the gain of the amplifier 1 to which the video signal vg is input. A/D converter 2
When the brightness data input from Hall 1?3 becomes equal to the reference data, the control signal output to the D/A converter 16 is changed to Hall 1? Then, the level of the control signal is written in the form of a digital signal to a predetermined address of the memory 15, that is, an address corresponding to the area S1 of the liquid crystal display panel 30.

Similarly, each area S2 of the liquid crystal display board 3. S5゜...
. . . Brightness information is similarly detected for l511 and recorded at a predetermined location in the memory 15.

As a result, data corresponding to the uneven brightness of the liquid crystal display panel 3 is written into the memory 15 by 1 degree.

In this case, the sample data regarding the brightness detected from the photoelectric conversion element 21 by the calculation of the microprocessor 24 is complemented by, for example, the least squares method, to create information on brightness unevenness in a narrower area, and to record it in the memory 15. You can do it like this.

If data regarding such brightness unevenness is input into the nonvolatile memory 15 at the manufacturing stage, it becomes possible to use the television receiver with the detection section 2o separated.

The liquid crystal display device of the present invention has a liquid crystal display panel 3 as described above.
Memory 1 in which brightness unevenness information is recorded in advance
5 is provided in the correction signal generating circuit section 1o, so that when inputting the video signal s and displaying an image, for example, the first clock signal from the horizontal and vertical clock signals for scanning the liquid crystal display panel 3 is simultaneously input. , second frequency dividing circuits 11 and 12, and counters 13 and 14, data regarding brightness unevenness is read from the memory 15,
Using this data, the level of the video signal is controlled for each field so that uneven brightness does not occur. That is, the data being sequentially read from the memory 15 is
Converter 16. It is added as a gain control signal to the amplifier 1 that amplifies the video signal Vs via the low and Q filter 17, so that when scanning an area of the liquid crystal display panel 3 with low brightness, for example, the video signal Vs is Amplify the level to make it brighter and control the brightness evenly.

It is more effective to correct the brightness unevenness of the liquid crystal display board 3 in a small area, but since the brightness unevenness of the liquid crystal display board 3 usually occurs over a fairly wide area, it is necessary to divide the area into several areas. Even in some cases, sufficient effects can be seen.

Note that the first and second frequency dividing circuits 11 and 12 counter 13 which form the address signal in the correction signal generation circuit part
, 14 can be omitted if they are generated by processing a scanning signal of X, Y-shift l/dimetre 4°5.

It goes without saying that the present invention is not limited to the television receiver shown in the embodiment and can be used for other display devices, such as graphic display devices.

〔Effect of the invention〕

As explained above, the liquid crystal display device of the present invention uses an electronic circuit to correct uneven brightness caused by uneven thickness of a matrix type liquid crystal display panel, so it is particularly suitable for large display devices. When applied, it has the advantage of not requiring the use of an expensive liquid crystal display panel.

Another advantage is that even if the optical characteristics of the liquid crystal display panel change over time and uneven brightness occurs, it can be easily resolved by replacing the memory in which brightness information is recorded. In particular, when applied to color television receivers where gradation is important, a significant improvement in image quality is expected.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a drive circuit for a liquid crystal display panel when the liquid crystal display device of the present invention is applied to a television receiver;
FIG. 2 is a block diagram showing a general driving circuit for a matrix-quizo liquid crystal display panel, and FIG. 3 is a characteristic diagram showing the relationship between light transmittance of a liquid crystal cell and applied voltage. In the figure, l is an amplifier with gain control, and 3 is a 7
Trix type liquid crystal display board, 4.5 is X, respectively.
Y-shift register, 10 is a correction signal generation circuit section, 15
2 is a memory, 20 is a detection unit for detecting uneven brightness, 21 is a photoelectric conversion element, and 24 is a microprocessor.

Claims (1)

[Claims] In a liquid crystal display device that displays an image using a liquid crystal matrix panel whose transmittance changes depending on the level of an applied signal, data obtained by detecting brightness information of the liquid crystal matrix panel for each of a plurality of areas is stored. 1. A liquid crystal display device comprising a memory circuit and configured such that a display signal supplied to the liquid crystal matrix panel is sequentially controlled by data output from the memory.