JP3957897B2 - Liquid crystal image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal image display apparatus, and more particularly to an apparatus having an information electrode drive circuit for realizing optimal control for correcting the color tone of a display image.
[0002]
[Prior art]
In recent years, flat panel displays using liquid crystal, which is thinner, lighter, and consumes less power than conventional CRT displays, have been attracting attention. Compared to this, the image quality adjustment function is poor.
[0003]
FIG. 2 is a block diagram showing a configuration of an information electrode driving circuit (hereinafter also referred to as a source driver) in such a conventional liquid crystal display. In the figure, 21 is a control circuit for generating chip enable signals EIO1 and EIO2 and controlling internal timing signals, and 22 is an image data bus (for R data: ID (5: 0), G data: ID ( 15:10), for B data: ID (25:20)), a latch address selector for generating a latch signal for sequentially taking in image data, 23 is 240 output channels × 6 bits (64 gradations) ) Is a first data latch composed of a 240 × 6 bit latch circuit that sequentially captures image data of 24), and a second data latch 24 captures 240 × 6 bit image data captured by the data latch 23 in synchronization with the signal LATCH. The data latch 25 generates 64 gray scale voltages based on the liquid crystal drive reference voltages (V8 to V0), and generates 6-bit data. DA converter to select a liquid crystal driving voltage in the decoding signal obtained by decoding the data, 26 is an output amplifier for supplying the liquid crystal driving voltage from the DA converter 25 to the liquid crystal panel.
[0004]
FIG. 3 is a block diagram showing a connection image when a plurality of 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 drive voltage output applied to the liquid crystal panel 30.
[0005]
3, reference numerals 37-1 to 37-n denote the source drivers shown in FIG. 2, and the source drivers 37-1 and 37-2 are connected to the terminals EIO2 and EIO1 by the source drivers 37- (n-1). ) And 37-n are serially connected to the respective terminals EIO2 and EIO1, and the terminal EIO1 of the source driver 37-1 is a signal SDI which is an image data fetch enable signal from a liquid crystal drive controller (not shown). (Serial Data In) is connected. Liquid crystal drive reference voltages (V8 to V0) are also input to each source driver, but are not shown in FIG.
[0006]
As shown in the timing chart of FIG. 4, the source driver 37-1 in FIG. 3 is latched in FIG. 2 at the timing of the falling edge of the signal SCLK when the signal SDI from the liquid crystal drive controller is high. Image data ID (5: 0), ID (15:10) and ID (25:20) are sampled and latched with respect to the data latch 23 according to the designated address of the address selector 22. The source driver 37-1 samples the image data during the 80 cycle period of the signal SCLK (240 output channels / 3-system image data bus), and outputs the signal SDO1 that becomes the chip enable signal of the source driver 37-2 for sampling. To stop. Source drivers after the source driver 37-2 also sample and latch image data at the same timing as described above. In this way, sampling and latching of the image data for one cycle of the signal LATCH, that is, one horizontal scanning period (1H) is completed, and the image data is latched in the data latch 24 of FIG. 2 in synchronization with the signal LATCH. The
[0007]
FIG. 5 shows a configuration of the DA converter 25 of 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 terminals V8 to V0 is composed of eight series resistors, and according to the input data, the voltage values divided by the resistor ladder according to the relation table of FIG. This is selected and supplied to the output amplifier 26. In this way, 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.
[0008]
FIG. 7 shows the relationship between the drive voltage (V) and the transmittance (T) of the liquid crystal panel 30. This figure shows that the 64 voltage values selected by the DA converter 25 in FIG. 2 correspond to the transmittance of the liquid crystal panel of 64 levels.
[0009]
[Problems to be solved by the invention]
In such a conventional liquid crystal image display device, it is conceivable that the color tone is simply corrected by changing the value of the liquid crystal drive reference voltage (V8 to V0) input to the source driver. However, according to this, there is a concern that the color tone cannot be independently corrected for each color of RGB, and that the cost of the power supply for the liquid crystal drive reference voltages V8 to V0 is increased.
[0010]
An object of the present invention is to make it possible to perform color tone correction independently for each color of RGB in a liquid crystal image display device with a simple configuration in view of the problems of the prior art. It is in.
[0011]
[Means for Solving the Problems]
In order to achieve this object, the liquid crystal image display device of the present invention includes a liquid crystal panel in which scanning electrodes and information electrodes are arranged in a matrix and sandwiching liquid crystal therebetween, and the information based on given image data. In a liquid crystal image display device comprising a plurality of information electrode driving means for applying an information signal voltage to the electrodes,
The information electrode driving means includes an image data input terminal for receiving the image data, a bit width extending means for extending the bit width of the image data, and adding correction data to the image data with the bit width extended or Adding and subtracting means for subtracting ,
The correction data includes correction data for each color of R, G, B, and the addition / subtraction means uses the correction data for each color of R, G, B with respect to the image data for each color of R, G, B. It is characterized by adding or subtracting every time .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
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 separately receives the image data input terminal for receiving the image data and the correction data. A correction data input terminal for receiving is provided.
[0013]
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 image data after the extension.
[0014]
The correction data includes correction data for each color of R, G, and B, and the addition / subtraction means adds or subtracts this correction data for each color of R, G, and B from the image data. Thus, independent color tone correction is performed for each color. The bus width of the correction data may be any one of 2 bits to the bus width of the image data.
[0015]
【Example】
FIG. 1 is a block diagram showing a configuration of a source driver of a liquid crystal image display device according to an embodiment of the present invention. In the figure, reference numerals 21 to 26 are the same as those of FIG. Reference numeral 17 denotes an adding / subtracting circuit according to the characteristic part of the present invention. Each of the RGB data has a 3-bit width for each of the image data ID (5: 0), ID (15:10) and ID (25:20). An image for correcting tone by using R correction data CID (2: 0), G correction data CID (12:10), and B correction data CID (22:20) (CID: Corrected Image Data) as correction data. Data addition / subtraction processing is performed. These correction data are also sent from the liquid crystal drive controller or the like.
[0016]
FIG. 8 is a timing chart of each control signal shown in FIG. 1 and a drive voltage output applied to the liquid crystal panel. The latch timing and the like are the same as in the conventional example (FIG. 4), but the data latched in the first data latch 23 is image data corrected by the correction data in the adjusting circuit 17.
[0017]
FIG. 9 shows the relationship between the input data of the adjusting circuit 17 and the correction level. According to this, the addition or subtraction process is determined by CIDx2 (x = 2, 1, 0) which is the MSB of each correction data, and by CIDx1 and CIDx0 (x = 2, 1, 0) of the lower 2 bits, The number of bits to be corrected is determined.
[0018]
That is, according to FIG. 6 shown in the conventional example and FIG. 9 in 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 to 2-bit addition and becomes 09H, and V6 + (V7−V6) × 6/8 is selected as the output voltage. Compared with the conventional example, the output voltage V7 is selected in the past when the image data ID (5: 0) is 07H, but according to the present embodiment, the same input image data 07H, V6 + (V7−V6) × 6/8 is selected, thereby changing the transmittance of the liquid crystal panel and correcting the R color tone.
[0019]
Similarly, if the G image data ID (15:10) is 28H and the correction data CID (12:10) is 07H, the image data is corrected by subtracting 3 bits to 25H, and the output voltage is V3 + (V4− V3) × 2/8 is selected. Compared with the conventional example, the output voltage V2 + (V3−V2) × 7/8 is selected when the image data ID (15:10) is 28H, whereas according to the present embodiment. In the same input image data 28H, 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. Become. Similarly, it is possible to correct the tone by correcting the B image data ID (25:20).
[0020]
That is, as shown in FIG. 15, the relationship between the drive voltage (V) to the liquid crystal panel and the transmittance (T) is shift-corrected in the horizontal axis (V) direction, resulting in a variation in characteristics of the liquid crystal panel between RGB. It is possible to adjust the color tone shift and to adjust the color tone of each of RGB independently of the image data.
[0021]
As described above, it is possible to perform color correction independently for each color of RGB by correcting the image data with each color correction image data for the RGB image data to the source driver. It becomes. In the embodiment described above, the bus width of the correction data is 3 bits each, but it is needless to say that the present invention is not limited to this and can be realized with a width of 2 to 6 bits.
[0022]
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. The elements 31 to 36 in the figure correspond to the elements 21 to 26 in FIGS. 1 and 2, respectively, and have the same function, but the number of bits of the data latches 33 and 34 and the DA converter 35 is 6 bits. To 8 bits. Reference numerals 38 and 39 respectively denote an addition / subtraction circuit and a bit conversion circuit according to the characteristic part of the present invention. FIG. 11 is a block diagram showing their configuration.
[0023]
As shown in FIG. 11, the bit conversion circuits 39 (39-1 to 39-3) receive 6-bit width image data ID (5: 0), ID (15:10), and ID (25:20), respectively. , Shift the upper 2 bits to 8 bits wide (lower 2 bits are 0). Therefore, the number of gradations that can be controlled by the image data is 2 ⁸ = 256 gradations. The adjusting circuit 38 (38-1 to 38-3) converts the expanded 8-bit image data into R-correction data CID (2: 0) and G-correction data CID (12:10) each having a 3-bit width. And B correction data CID (22:20) (CID: Corrected Image Data) is used to add / subtract image data for correcting tone. Each correction data is also sent from a liquid crystal drive controller or the like.
[0024]
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 in the first data latch 33 is corrected by the bit conversion circuit 39 and the adjustment circuit 38. The image data corrected by is latched.
[0025]
FIG. 12 shows a configuration of the DA converter 35 of 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 resistance ladders. Each power supply terminal is composed of 32 series resistors, and the liquid crystal drive voltage supplied to the output amplifier 36 is divided by a resistor ladder according to the input data according to the relational table shown in FIG. Each voltage value is selected.
[0026]
FIG. 14 shows the relationship between the drive voltage (V) to the liquid crystal panel and the transmittance (T). This figure shows that 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.
[0027]
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, the addition or subtraction processing is determined by CIDx2 (x = 2, 1, 0) which is the MSB of each correction data, and the lower two bits CIDx1 and CIDx0 (x = 2, 1, 0) The number of bits to be corrected is determined.
[0028]
That is, according to FIG. 9 and FIG. 13, 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 addition of 2 bits and 1EH. Thus, V7 + (V8−V7) × 1/32 is selected as the output voltage. Compared to the conventional example, the output voltage V7 is selected when the image data ID (5: 0) is 07H, whereas according to the present embodiment, the same input image data 07H is used. V7 + (V8−V7) × 1/32 is selected, whereby the transmittance of the liquid crystal panel can be changed, thereby correcting the R color tone. In addition, as compared with the above-described embodiment, since the image data input with a 6-bit width is expanded to 8 bits and then corrected, the adjustment range of the color tone can be adjusted for every 256 gradation levels. Thus, it becomes possible to perform color tone correction more finely.
[0029]
Similarly, if the G image data ID (15:10) is 3BH and the correction data CID (12:10) is 07H, the image data is 3-bit subtracted and corrected to E9H, and the output voltage is V0 + ( V1-V0) × 22/32 is selected. Compared with the conventional example, conventionally, when the image data ID (15:10) is 3BH, the output voltage V0 + (V1−V0) × 4/8 is selected. In the same input image data 3BH, V0 + (V1−V0) × 22/32 is selected, whereby the transmittance of the liquid crystal panel can be changed, thereby correcting the color tone of G. Become. In addition, as compared with the above-described embodiment, since the image data input with a 6-bit width is expanded to 8 bits and then corrected, the adjustment range of the color tone can be adjusted for every 256 gradation levels. Thus, it becomes possible to perform color tone correction more finely. Similarly, it is possible to correct the tone by correcting the B image data ID (25:20).
[0030]
That is, as shown in FIG. 16, the relationship between the drive voltage (V) to the liquid crystal panel and the transmittance (T) is shift-corrected in the horizontal axis (V) direction, resulting in a variation in characteristics of the liquid crystal panel between RGB. It is possible to adjust the color tone shift and to adjust the color tone of each of RGB independently of the image data.
[0031]
As described above, according to the present embodiment, the RGB image data to the source driver is corrected for the image data by each color correction image data after extending the bit width. It becomes possible to finely correct the color tone independently for each of the RGB colors.
[0032]
【The invention's effect】
As described above, according to the present invention, the predetermined correction data is added to or subtracted from the image data in order to correct the color tone. Therefore, the color tone correction can be performed independently for each of the RGB colors with a simple configuration. Can be performed.
[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.
5 is a block diagram of a DA converter in a source driver in the conventional example and the embodiment of FIG.
6 is a table showing the relationship between the input data of the DA converter of FIG. 5 and the liquid crystal drive voltage output.
FIG. 7 is a graph showing a relationship between drive voltage and 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 the relationship between the input data to the adjusting circuit in the source driver of FIG. 1 and the 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 adjustment circuit in the source driver of 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 of FIG. 12 and liquid crystal drive voltage output.
14 is a table showing the relationship between the drive voltage to the liquid crystal panel by the source driver of FIG. 10 and the transmittance.
15 is a diagram showing a correction image of the relationship between the drive voltage to the liquid crystal panel and the transmittance in the image display apparatus of FIG. 1. FIG.
16 is a diagram showing a correction image of the relationship between the drive voltage to the liquid crystal panel and the transmittance by the source driver of FIG.
[Explanation of symbols]
21, 31: control circuit, 22, 32: latch address selector, 23, 33: first data latch, 24, 34: second data latch, 25, 35: DA converter, 26, 36: output amplifier, 17 , 38: adjustment circuit, 30: liquid crystal panel, 39: bit conversion circuit, 37: source driver.

Claims (2)

A liquid crystal panel in which scanning electrodes and information electrodes are arranged in a matrix and sandwiching liquid crystal therebetween, and a plurality of information electrode driving means for applying an information signal voltage to the information electrodes based on given image data In a liquid crystal image display device comprising:
The information electrode driving means includes an image data input terminal for receiving the image data, a bit width extending means for extending the bit width of the image data, and adding correction data to the image data with the bit width extended or Adding and subtracting means for subtracting ,
The correction data includes correction data for each color of R, G, B, and the addition / subtraction means uses the correction data for each color of R, G, B with respect to the image data for each color of R, G, B. A liquid crystal image display device characterized in that addition or subtraction is performed every time . 2. The liquid crystal image display device according to claim 1 , wherein a bus width of the correction data is any one of a 2-bit width to a bus width of the image data.

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