JP2000111866A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [Problem] To enable independent correction of color tone for each of RGB colors with a simple configuration. SOLUTION: A scanning electrode and an information electrode are arranged in a matrix with each other, and a liquid crystal panel is interposed between the scanning electrode and the information electrode; and an information electrode drive for applying an information signal voltage to the information electrode based on given image data. And a means for adding or subtracting predetermined correction data to or from the image data in order to perform color tone correction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly to a liquid crystal display having an information electrode driving circuit for realizing optimal control for correcting a color tone of a displayed image.

[0002]

2. Description of the Related Art In recent years, a flat panel display using a liquid crystal which is thinner, lighter and consumes less power than a CRT display which has been widely used in the past has attracted attention. As an issue, it is mentioned that the image quality adjustment function is poor as compared with the CRT.

FIG. 2 is a block diagram showing a configuration of an information electrode drive circuit (hereinafter, also referred to as a source driver) in such a conventional liquid crystal display. In the figure,
Reference numeral 21 denotes a control circuit for generating chip enable signals EIO1 and EIO2 and controlling an internal timing signal. Reference numeral 22 denotes an image data bus (for R data: ID (5: 0), for G data: ID (15: 1).
0), for B data: a latch address selector for generating a latch signal for sequentially taking in image data inputted via ID (25:20), 23 is 240 output channels × 6 bits (64 gradations) A first data latch 24 composed of a latch circuit of 240 × 6 bits that sequentially captures image data,
A second data latch, which captures 40 × 6 bit image data in synchronization with the signal LATCH, generates a voltage of 64 gradations based on the liquid crystal drive reference voltage (V8 to V0),
A DA converter 26 selects a liquid crystal drive voltage based on a decode signal obtained by decoding 6-bit data. An output amplifier 26 supplies the liquid crystal drive voltage from the DA converter 25 to the liquid crystal panel.

FIG. 3 is a block diagram showing a connection image when a plurality of the source drivers are mounted on the liquid crystal panel 30. FIG. 4 is a timing chart of the control signals shown in FIG. 2 and the driving voltage output applied to the liquid crystal panel 30.

In FIG. 3, reference numerals 37-1 to 37-n denote source drivers shown in FIG.
-1 and 37-2 have their terminals EIO2 and EIO1 connected to each other, and the source drivers 37- (n-1) and 37-n also have their terminals EIO2 and EIO1 connected serially. A signal SDI (serial data signal), which is an image data capture enable signal from a liquid crystal drive controller (not shown),
(Serial Data In) is connected. The liquid crystal drive reference voltages (V8 to V0) are also input to each source driver, but are not shown in FIG.

As shown in the timing chart of FIG. 4, the source driver 37-1 in FIG. 3 operates at the timing of the falling edge of the signal SCLK when the signal SDI from the liquid crystal drive controller is high.
The image data ID (5:
0), ID (15:10) and ID (25:20) are sampled and latched. Source driver 37-
Reference numeral 1 denotes sampling of image data during an 80 cycle period of the signal SCLK (240 output channels / 3 image data buses), outputting a signal SDO1 serving as a chip enable signal of the source driver 37-2, and stopping sampling. Source drivers after the source driver 37-2 also perform sampling and latching of image data at the same timing as described above. Thus, the signal LAT
One cycle of CH, that is, sampling and latching of image data for one horizontal scanning period (1H) are completed, and the signal LAT
In synchronization with the CH, the image data is stored in the data latch 24 of FIG.
Latched.

FIG. 5 shows the configuration of the DA converter 25 shown in FIG. FIG. 6 shows the relationship between the input data to the DA converter 25 and the liquid crystal drive voltage output. As shown in FIG. 5, the reference voltage of the DA converter 25 is composed of a total of 64 resistor ladders. Each of the power supply terminals V8 to V0 is constituted by eight series resistors. According to the input data, the respective voltage values divided by the resistor ladder as the liquid crystal drive voltage according to the relation table of FIG. It is selected and supplied to the output amplifier 26. Thus, the liquid crystal driving voltage selected for each output channel is applied to the liquid crystal panel 30 via the output amplifier 26 of FIG.

FIG. 7 shows the driving voltage (V) of the liquid crystal panel 30.
And the transmittance (T). This figure shows that 64 types of voltage values selected by the DA converter 25 of FIG.
It corresponds to the transmittance of the liquid crystal panel at the level.

[0009]

The correction of the color tone in such a conventional liquid crystal image display device is performed simply by changing the value of the liquid crystal driving reference voltage (V8 to V0) input to the source driver. Can be considered. However, according to this, the color tone cannot be corrected independently for each of the RGB colors, and the liquid crystal driving reference voltages V8 to V8
There is a concern about a problem such as an increase in the cost of the 0 power supply.

An object of the present invention is to provide a liquid crystal image display device capable of performing color tone correction with a simple configuration and independently for each of RGB colors in view of the problems of the prior art. It is to make.

[0011]

According to the present invention, there is provided a liquid crystal panel having scanning electrodes and information electrodes arranged in a matrix with each other and having a liquid crystal interposed therebetween. An information electrode driving means for applying an information signal voltage to said information electrode based on said information electrode, wherein an addition / subtraction means for adding or subtracting predetermined correction data to or from said image data in order to perform color tone correction is provided. It is characterized in that the color tone can be corrected independently for each of the RGB colors with a simple configuration.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the present invention, the addition / subtraction means is provided in the information electrode driving means, and the information electrode driving means has an image data input terminal for receiving image data, and an image data input terminal for receiving image data. Separately, a correction data input terminal for receiving correction data is provided.

Further, before adding or subtracting the correction data to or from the image data, there is provided a bit width extending means for extending the bit width of the image data, and the information electrode driving means corresponds to the expanded image data. ing.

The correction data includes correction data for each of R, G, and B colors, and the addition / subtraction means adds or subtracts this correction data to the image data for each of R, G, and B colors. . As a result, independent color tone correction is performed for each color. The bus width of the correction data may be any one of from a 2-bit width to the bus width of the image data.

[0015]

FIG. 1 is a block diagram showing a configuration of a source driver of a liquid crystal display according to an embodiment of the present invention.
2, reference numerals 21 to 26 are the same as those in FIG. Reference numeral 17 denotes an addition / subtraction circuit according to a characteristic portion of the present invention, which includes image data ID (5: 0) and ID (1).
5:10) and ID (25:20), respectively.
R, which is correction data having a 3-bit width for each color of GB
Correction data CID (2: 0), G correction data CID (1
2:10) and B correction data CID (22:20)
(CID: Corrected Image Dat
According to a), the image data is added or subtracted for color tone correction. These correction data are also sent from a liquid crystal drive controller or the like.

FIG. 8 is a timing chart of the control signals shown in FIG. 1 and the driving voltage output applied to the liquid crystal panel. The latch timing and the like are the same as those in the conventional example (FIG. 4), but the data latched by the first data latch 23 is the image data corrected by the correction data in the addition / subtraction circuit 17.

FIG. 9 shows the relationship between the input data of the adjustment circuit 17 and the correction level. According to this, MS of each correction data
Addition or subtraction processing is determined by CIDx2 (x = 2, 1, 0) of B, and CIDx1 of lower two bits is determined.
And CIDx0 (x = 2, 1, 0) determine the number of bits to be corrected.

That is, according to FIG. 6 showing the conventional example and FIG. 9 showing the present embodiment, if the R image data ID (5: 0) is 07H and the correction data CID (2: 0) is 02H, The image data is corrected by adding two bits to become 09H, and the output voltage is selected to be V6 + (V7-V6) × 6/8. Compared with the conventional example, the output voltage V7 is conventionally selected when the image data ID (5: 0) is 07H, but according to the present embodiment, the same input image data 07H is used according to the present embodiment. V6 + (V7−V6) × 6/8 is selected, thereby changing the transmittance of the liquid crystal panel,
This means that the color tone of R has been corrected.

Similarly, the G image data ID (15:
10) is 28H, correction data CID (12:10) is 0
7H, the image data is subjected to 3-bit subtraction correction and
5H, and the output voltage is V3 + (V4−V3) × 2/8
Will be selected. Compared with the conventional example, the output voltage V2 + (V3−V2) × 7/8 is conventionally selected when the image data ID (15:10) is 28H. , The same input image data 2
At 8H, V3 + (V4−V3) × 2/8 is selected, whereby the transmittance of the liquid crystal panel can be changed, thereby correcting the color tone of G. Similarly, it is possible to correct the color tone by correcting the B image data ID (25:20).

That is, as shown in FIG. 15, the relationship between the drive voltage (V) and the transmittance (T) to the liquid crystal panel is shifted and corrected in the horizontal axis (V) direction, so that the RGB of the liquid crystal panel is varied due to the characteristic variation of the liquid crystal panel. It is possible to adjust the color tone shift occurring between them, and to adjust the color tone of each of RGB independently of the image data.

As described above, the RG to the source driver
By performing image data correction on each image data of B with each image data for color tone correction, RGB
The color tone can be corrected independently for each color.
In the embodiment described above, the bus width of the correction data is set to 3 bits, but it is needless to say that the correction data can be realized with a width of 2 to 6 bits.

FIG. 10 is a block diagram showing a configuration of a source driver of a liquid crystal image display device according to another embodiment of the present invention. Each of the elements 31 to 36 in FIG.
26 correspond to the respective elements and have the same functions, but the number of bits of the data latches 33 and 34 and the DA converter 35 is expanded from 6 bits to 8 bits. Reference numerals 38 and 39 denote an addition / subtraction circuit and a bit conversion circuit according to the characteristic portion of the present invention, respectively. FIG. 11 is a block diagram showing the configuration.

As shown in FIG. 11, the bit conversion circuit 39
(39-1 to 39-3) are image data ID (5: 0), ID (15:10), and ID (2
5:20) is shifted by 2 bits to the higher order to have an 8-bit width (the lower 2 bits are 0). Therefore, the number of gradations that can be controlled by the image data is 2 ⁸ = 256 gradations. The adding / subtracting circuits 38 (38-1 to 38-3) convert the expanded 8-bit image data into the 3-bit R correction data CID (2: 0) and the G correction data CID (12:
10) and B correction data CID (22:20) (CI
D: A process for adding or subtracting image data for correcting a color tone using Corrected Image Data. Each correction data is also transmitted from a liquid crystal drive controller or the like.

The latch timing and the like are the same as those in the conventional example (FIG. 4) and the above-described embodiment (FIG. 8), but the data latched by the first data latch 33 is a bit conversion circuit 39.
The image data corrected by the correction data in the addition / subtraction circuit 38 is latched.

FIG. 12 shows the configuration of the DA converter 35 shown in FIG. FIG. 13 shows the relationship between the input data to the DA converter 35 and the liquid crystal drive output voltage. As shown in FIG. 12, the reference voltage of the DA converter 35 is composed of a total of 256 resistor ladders. Each power supply terminal is composed of 32 series resistors, and the liquid crystal drive voltage supplied to the output amplifier 36 depends on the input data.
In accordance with the relational table shown in (1), each voltage value divided by the resistance ladder is selected.

FIG. 14 shows the relationship between the driving voltage (V) applied to the liquid crystal panel and the transmittance (T). This figure shows that the 256 kinds of voltage values selected by the DA converter 35 in FIG. 10 correspond to the 256-level transmittance of the liquid crystal panel.

The relationship between the input data of the adjusting circuit 38 and the correction level is the same as that shown in FIG. According to this,
CIDx2 (x = 2, 1,...) Which is the MSB of each correction data
0) determines the addition or subtraction processing,
The number of bits to be corrected is determined by the bits CIDx1 and CIDx0 (x = 2, 1, 0).

That is, according to FIG. 9 and FIG. 13, the R image data ID (5: 0) is 07H and its correction data CID
If (2: 0) is 02H, the image data is added and corrected by 2 bits to become 1EH, and the output voltage becomes V7 + (V8
−V7) × 1/32 will be selected. Compared with the conventional example, the image data ID (5: 0) is conventionally 07
In the case of H, the output voltage V7 is selected, but according to the present embodiment, the same input image data
+ (V8−V7) × 1/32 is selected, whereby
The transmittance of the liquid crystal panel can be changed, which means that the color tone of R has been corrected. In addition, compared to the above-described embodiment, since the image data input with a 6-bit width is expanded to 8 bits and then corrected, the color tone adjustment width can be adjusted for every 256 gradation levels Thus, the color tone can be more finely corrected.

Similarly, the G image data ID (15:
10) is 3BH and its correction data CID (12: 1)
If (0) is 07H, the image data is subjected to 3-bit subtraction correction and becomes E9H, and the output voltage is V0 + (V1-V0).
× 22/32 will be selected. Compared with the conventional example, the image data ID (15:10) is 3BH
At this time, the output voltage V0 + (V1−V0) × 4/8 is selected. According to the present embodiment, however, V0 + (V1−V0) × 22/32 with the same input image data 3BH.
Is selected, whereby the transmittance of the liquid crystal panel can be changed, thereby correcting the G color tone. In addition, as compared with the above-described embodiment, image data input with a 6-bit width is expanded to 8 bits, and then correction is performed.
Adjustment can be performed for every 56 gradation levels, and it is possible to perform finer color tone correction. Similarly, it is possible to correct the color tone by correcting the B image data ID (25:20).

That is, as shown in FIG. 16, the relationship between the driving voltage (V) and the transmittance (T) to the liquid crystal panel is shifted and corrected in the horizontal axis (V) direction, so that the RGB of the liquid crystal panel is varied due to variations in the characteristics of the liquid crystal panel. It is possible to adjust the color tone shift occurring between them, and to adjust the color tone of each of RGB independently of the image data.

As described above, according to the present embodiment, the bit width of each of the RGB image data to the source driver is expanded, and then the image data is corrected by each color tone image data. Therefore, it is possible to perform finer color tone correction independently for each of the RGB colors.

[0032]

As described above, according to the present invention, predetermined correction data is added to or subtracted from image data in order to perform color tone correction. Thus, the color tone can be corrected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a source driver of a liquid crystal image display device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a source driver according to a conventional example.

FIG. 3 is a block diagram showing an image of mounting a source driver on a liquid crystal panel.

FIG. 4 is an input / output timing chart of a conventional source driver.

FIG. 5 is a block diagram of a DA converter in a source driver in the conventional example and the embodiment of FIG. 1;

6 is a table showing a relationship between input data of the DA converter in FIG. 5 and output of a liquid crystal drive voltage.

FIG. 7 is a graph showing a relationship between a driving voltage and a transmittance of a liquid crystal panel.

FIG. 8 is an input / output timing chart of the source driver of FIG. 1;

FIG. 9 is a table showing a relationship between input data to an adjusting circuit in the source driver of FIG. 1 and a correction level;

FIG. 10 is a block diagram showing a configuration of a source driver according to another embodiment of the present invention.

11 is a block diagram showing a configuration of a bit conversion circuit and an addition / subtraction circuit in the source driver of FIG.

FIG. 12 is a circuit diagram of a DA converter in the source driver of FIG.

13 is a table showing a relationship between input data to the DA converter in FIG. 12 and liquid crystal drive voltage output.

14 is a table showing a relationship between a driving voltage applied to a liquid crystal panel by the source driver of FIG. 10 and transmittance.

FIG. 15 is a diagram showing a correction image of a relationship between a drive voltage to a liquid crystal panel and transmittance in the image display device of FIG. 1;

16 is a diagram showing a correction image of a relationship between a driving voltage applied to a liquid crystal panel and a transmittance by the source driver of FIG. 10;

[Explanation of symbols]

21, 31: control circuit, 22, 32: latch address selector, 23, 33: first data latch, 2
4, 34: second data latch, 25, 35: DA converter, 26, 36: output amplifier, 17, 38: addition / subtraction circuit, 30: liquid crystal panel, 39: bit conversion circuit, 37:
Source driver.

Continued on the front page F-term (reference) 2H093 NA07 NA43 NA53 NA64 NC13 NC22 NC26 NC50 NC65 ND06 ND17 ND24 ND34 ND49 5C006 AA16 AA22 AF46 AF52 AF83 BB11 BC12 BF03 BF04 BF24 BF25 BF28 BF43 FA18 FA41 FA56 5C080 A03 DD03 JJ04 JJ05 5C082 BA34 CA12 CB01 DA86 MM06 MM09

Claims (5)

[Claims] 1. A liquid crystal panel having a scanning electrode and an information electrode arranged in a matrix with liquid crystal interposed therebetween, and an information electrode for applying an information signal voltage to the information electrode based on given image data. A liquid crystal image display device comprising a driving unit and an addition / subtraction unit for adding or subtracting predetermined correction data to or from the image data in order to correct a color tone. 2. The information electrode driving means is provided in the information electrode driving means. The information electrode driving means includes an image data input terminal for receiving the image data, and separately from the image data input terminal. 2. The liquid crystal image display device according to claim 1, further comprising a correction data input terminal for receiving the data. 3. The method according to claim 1, further comprising: a bit width expansion unit that expands a bit width of the image data before the addition or the subtraction, and wherein the information electrode driving unit corresponds to the expanded image data. The liquid crystal image display device according to claim 1 or 2, wherein: 4. The correction data includes correction data for each of R, G, and B colors, and the adding / subtracting means adds the correction data to the image data for each of R, G, and B colors. The liquid crystal image display device according to claim 1, wherein the liquid crystal image display device performs subtraction. 5. The liquid crystal image according to claim 1, wherein a bus width of the correction data ranges from a 2-bit width to a bus width of the image data. Display device.