JPH11327499A - Picture display device and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent that a display picture is made unnatural even if display resolution is changed. SOLUTION: This picture display device has a signal amplifying circuit 11 amplifying analog pixel data from a personal computer, an A/D conversion circuit 12 converting an output of the signal amplifying circuit 11 to digital pixel data, a first memory 13 storing converted digital pixel data, a data operation circuit performing luminance adjustment of digital pixel data, a second memory 15 storing digital pixel data after adjusting luminance, a liquid crystal module 16 of XGA standard, a display mode discriminating circuit 17 setting display resolution of the liquid crystal module 16, and a clock control circuit 18 supplying a clock signal and a control signal to each part of a liquid crystal display device 1. When display resolution of a liquid crystal panel 21 is changed, two adjacent pixels can be expanded almost uniformly so that the expansion ratio of pixel data corresponding to two adjacent pixels respectively do not exceed double.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device having a multi-scan function capable of changing the display resolution of a display device.

[0002]

2. Description of the Related Art In a conventional image display apparatus having a multi-scan function, the display resolution in the horizontal (horizontal) direction of a display screen is expanded in units of pixels by setting each color of RGB. For example, XGA (e
(Xtended Graphics Array) standard display device, 640 × 480
When setting the display resolution of the VGA (Video Graphics Array) standard consisting of dots, the pixels that expand twice in the horizontal direction and the pixels that remain the same size are mixed, and the horizontal pixel expansion rate of the entire screen is adjusted. It was set to 1.6 times.

FIG. 7 is a diagram for explaining a conventional method of enlarging pixels, and shows an example in which a horizontal pixel enlarging ratio is set to 1.5 times. In the case of FIG. 7, one of two adjacent pixels is enlarged by a factor of two, and the other is supplied to each signal line of the display device at the same magnification. This causes the pixel data to be displayed 1.5 times enlarged.

[0004]

However, if the enlarged display is performed with each of the RGB colors as a set as in the prior art,
Pixels that are enlarged twice and pixels that remain at the same size are mixed, and pixels that are enlarged twice are displayed with a large line width, so that the original image cannot be faithfully reproduced. Also,
Since the luminance increases as the line width increases, luminance unevenness occurs on the entire screen.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to provide an image display apparatus capable of enlarging each image substantially uniformly when the display resolution is changed, and a driving method thereof. Is to provide.

[0006]

According to a first aspect of the present invention, there is provided a display including an effective display area including a plurality of horizontal pixel lines in which a plurality of display pixels are arranged. A panel, a display panel driving circuit that supplies a voltage corresponding to image data to each of the display pixels of the horizontal pixel line of the display panel, and image data corresponding to the display pixel based on an input image signal. An image data generation circuit that generates and supplies the image data to the display panel drive circuit. The image signal is enlarged at a first ratio in the time axis direction, and each of the image signals corresponding to at least some display pixels in the horizontal pixel line other than the some display pixels. The expanding at a second ratio greater than said first ratio in the time axis direction includes data expansion means for generating the image data, the second ratio is set to be less than the first ratio.

According to a fourth aspect of the present invention, there is provided a pixel display section on which a plurality of signal lines and scanning lines are arranged, a signal line driving circuit for supplying pixel data to each of the signal lines at a predetermined timing, and the scanning line. And a scanning line driving circuit for driving the pixel lines. A display resolution setting unit configured to set a display resolution of the pixel display unit, and a display resolution setting unit corresponding to each of two pixels adjacent in the direction in which the signal lines are arranged. Pixel data enlarging means for enlarging each of the pixel data in accordance with the set display resolution so that the ratio of the enlarging ratio of each pixel data is less than twice, and the signal line driving circuit comprises: The enlarged pixel data is supplied to a corresponding signal line.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image display device according to the present invention will be specifically described with reference to the drawings. Hereinafter, a liquid crystal display device will be described as an example of the image display device.

FIG. 1 is a schematic block diagram of one embodiment of a liquid crystal display device 1. The liquid crystal display device 1 shown in FIG. 1 is driven by an analog color video signal supplied from a personal computer 2. This color video signal includes analog pixel data, a horizontal synchronization signal, and a vertical synchronization signal.

The liquid crystal display device 1 shown in FIG. 1 includes a signal amplifying circuit 11 for amplifying analog pixel data,
A / D conversion circuit 1 that converts the output of the image into digital pixel data
2, a first memory 13 for storing the converted digital pixel data, a data operation circuit 14 for adjusting the luminance of the digital pixel data, a second memory 15 for storing the digital pixel data after the luminance adjustment, and 1024 An XGA standard liquid crystal module 16 composed of × 768 color dots, a display mode discriminating circuit 17 for setting the display resolution of the liquid crystal module 16, and a clock signal and a control signal supplied to each unit in the liquid crystal display device 1 And a clock control circuit 18.

As shown in detail in FIG. 2, the liquid crystal module 16 includes a liquid crystal panel 21 having signal lines and scanning lines arranged vertically and horizontally, and a signal line driving circuit 22 for driving the signal lines.
And a scanning line driving circuit 23 for driving the scanning lines, and a liquid crystal controller 24 for controlling the driving timing of each driving circuit.

The liquid crystal panel 21 has an array substrate and a counter substrate which are arranged to face each other, and a liquid crystal material layer held between these substrates. The array substrate includes 1024 × 3 signal lines S, 768 scanning lines G, and 1024 × 768 × 3 thin film transistors (TFT) 31 formed near the intersection of the signal lines S and the scanning lines G; Similarly, it has 1024 × 768 × 3 pixel electrodes 32. The counter substrate has a counter electrode and a color filter layer. The color filter layer has red, green, and blue color stripes arranged in the column direction of the pixel electrodes. The liquid crystal material layer is bonded to an alignment film that entirely covers the surfaces of the array substrate and the counter substrate.

A liquid crystal controller 24 controls a horizontal clock signal for liquid crystal display and a horizontal start signal based on the digital pixel data read from the second memory 15 in FIG. 1 and the clock signal from the clock control circuit 18 in FIG. A signal, a vertical clock signal, and a vertical start signal are generated.

The liquid crystal display device 1 shown in FIG. 1 is capable of arbitrarily changing the display resolution of an XGA standard liquid crystal panel 21 in accordance with an instruction from a personal computer 2. Hereinafter, a method of switching the display resolution will be described with reference to FIG.

For example, the liquid crystal panel 21 is VGA standard 6
When setting the display resolution to 40 × 480 dots, the process of expanding one pixel of input pixel data to 1.66 pixels is performed continuously for four pixels, and then the input pixel data of one pixel is expanded to 1.33 pixels. The processing is performed for one pixel.

That is, as shown in FIG. 3A, after A / D conversion of the pixel data R1, G1, B1 of the first pixel,
Subsequently, the pixel data R1 and G1 are A / D converted again. As a result, the first pixel is enlarged and displayed 1.66 times. next,
For the second pixel, the pixel data B2, R2, and G2 are A / D converted, and then the pixel data B2 and R2 are again A / D converted. Similarly, for the third pixel and the fourth pixel, a part of the color data constituting the pixel data is A / D-converted twice to enlarge each pixel data by 1.66 times.

For the fifth pixel, pixel data B
After A / D conversion of 5, R5 and G5, only pixel data B5 is A / D converted again.
Convert to D. Thereby, the fifth pixel is enlarged 1.33 times.

By repeating the enlargement processing of 1 to 5 pixels shown in FIG. 3A thereafter, the liquid crystal panel 2 conforming to the XGA standard is obtained.
1 can be set to the display resolution of the VGA standard.

On the other hand, when the liquid crystal panel 21 of the XGA standard is set to the display resolution of 800 × 600 dots of the SVGA standard,
As shown in FIG. 3B, one pixel of input pixel data is
After performing the process of expanding to 1.33 pixels for 5 or 6 pixels continuously, the process of outputting the next input pixel data at the same size is repeated. However, when the display resolution of the SVGA standard is set, the ratio of the resolution is indivisible. Therefore, the case where the process of expanding to 1.33 pixels is performed continuously for 5 pixels and the case where it is performed continuously for 6 pixels are irregular. Will be lined up.

As described above, in the liquid crystal display device 1 of the first embodiment, even if the display resolution of the liquid crystal panel 21 is changed,
The ratio of the enlargement ratio of the pixel data corresponding to each of two adjacent pixels does not exceed twice. Therefore, two adjacent pixels can be substantially uniformly enlarged, and the image is not distorted even if the display resolution is switched.

In the liquid crystal display device 1 shown in FIG. 1, since a part of the color data constituting each pixel is supplied to different signal lines a plurality of times, the color data supplied a plurality of times and the color data supplied only once are provided. In this case, there is a possibility that a difference occurs in luminance, and luminance unevenness occurs.

Therefore, the data operation circuit 14 in the liquid crystal display device 1 of FIG. 1 performs a process of lowering the luminance of the color data supplied a plurality of times. This reduces the difference in luminance between the color data.

FIG. 4 is an operation timing chart of each part in the liquid crystal display device 1. Hereinafter, the operation of the liquid crystal display device 1 of FIG. 1 will be described with reference to FIG. When the analog pixel data ANA-R, ANA-G, ANA-B and the display clock CLK1 are output from the personal computer 2, the analog pixel data ANA-R, A
NA-G and ANA-B are input to the signal amplification circuit 11, and the display clock CLK1 is input to the display mode discrimination circuit 17. The display mode determination circuit 17 determines the display resolution of the liquid crystal panel 21 based on the frequency of the display clock CLK1. Specifically, it is determined whether the display resolution is one of the VGA standard, the SVGA standard, and the XGA standard. Information on the determined display resolution is sent to the clock control circuit 18.

The clock control circuit 18 sends a sampling clock corresponding to the display resolution determined by the display mode determination circuit 17 to the A / D conversion circuit 12. FIG. 4 shows an example in which display is performed on a liquid crystal panel 21 of the XGA standard at a display resolution of the VGA standard. When the analog pixel data R1, G1, B1 of the first pixel is supplied from the personal computer 2, the clock control circuit 18 samples the data R1, G1 twice, respectively, the sampling clocks CLK-R, CLK.
-G and a sampling clock CLK-B for sampling the data B1 once.

For the second pixel, the sampling clocks CLK-R and CLK-B sample the data R2 and B2 twice, respectively, and the sampling clock CLK-G samples the data G2 only once.

As described above, the three sampling clocks CLK-R, CLK-G and CLK-B are used for the first to fourth pixels.
Two sample the corresponding analog pixel data twice, and the remaining sampling clock samples the corresponding analog pixel data only once.

On the other hand, for the fifth pixel, the sampling clocks CLK-R and CLK-G are the analog pixel data R respectively.
5 and G5 are sampled once, and the sampling clock CLK-B samples the analog pixel data B5 twice.

The A / D conversion circuit 12 includes the clock control circuit 1
At the rising edges of the sampling clocks CLK-R, CLK-G, and CLK-B from step 8, analog pixel data is fetched and converted into digital pixel data. Thereby, as shown in FIG. 4, analog pixel data ANA-R becomes digital pixel data DIG-R, analog pixel data ANA-G becomes digital pixel data DIG-G, and analog pixel data ANA-B becomes digital pixel data. It is converted to DIG-B respectively.

The digital pixel data DIG-R, DIG-G, and DIG-B that have been A / D converted by the A / D conversion circuit 12 are stored in a first memory 13.
Are sequentially stored. The write clock and the enable signal to the first memory 13 are supplied from the clock control circuit 18.

When digital pixel data for one horizontal cycle or one frame is stored in the first memory 13, a read clock is supplied from the clock control circuit 18 to the first memory 13, and the read clock is supplied to the first memory 13. The stored data is sequentially read and input to the data operation circuit 14.

The data operation circuit 14 controls the digital pixel data DIG-R, DIG-G, DIG-G so that the luminance does not vary for each color.
Adjust the brightness of DIG-B. For example, in the case of the first pixel in FIG. 4, the red data R1 and the green data G1 are supplied twice to different signal lines, so that the luminance is higher than that of the blue data B1. For this reason, the data operation circuit 14 executes the same data multiple times,
When supplying the data to a different signal line, a process of reducing the luminance of the data is performed. Therefore, in the case of FIG. 4, the brightness of the red data R1 and the green data G1 is reduced for the first pixel and converted to data R1 'and G1', respectively, and the brightness of the red data R2 and the blue data B2 is reduced for the second pixel. Data R2 ', G respectively
Converted to 2 '. By such processing, the luminance does not vary for each color, and the display quality does not deteriorate even if the display resolution of the liquid crystal panel 21 is changed.

The output of the data operation circuit 14 is sequentially stored in the second memory 15 according to the write clock from the clock control circuit 18. The digital pixel data stored in the second memory 15 is sequentially read out according to the read clock from the clock control circuit 18 and supplied to the signal line drive circuit 22 in the liquid crystal module 16.

In FIG. 4, the clock supplied to the liquid crystal module 16 is represented by a waveform CLK2, and the output of the data operation circuit 14 is represented by waveforms OUT-R, OUT-G, and OUT-B for each color.

As described above, the liquid crystal display device 1 of the present embodiment
Determines the display resolution of the liquid crystal panel 21 according to the frequency of the display clock CLK1 supplied from the personal computer 2, and the ratio of the enlargement ratio of the pixel data corresponding to each of two adjacent pixels does not exceed twice. Thus, even if the display resolution is changed, the pixel data is not unevenly enlarged.

In the vertical direction of the liquid crystal panel 21, by driving a plurality of adjacent scanning lines at the same time, enlarged display in the vertical direction becomes possible.

(Second Embodiment) In the second embodiment, digital pixel data is supplied from the personal computer 2 to the liquid crystal display device 1.

FIG. 5 is a block diagram of a second embodiment of the image display device, and shows the configuration of the liquid crystal display device as in the first embodiment. The liquid crystal display device 1a shown in FIG.
It is characterized in that a sampling circuit 19 is provided instead of the conversion circuit 12.

The sampling circuit 19 shown in FIG. 5 samples digital pixel data (DIG1-R, DIG1-G, DIG1-B) supplied from the personal computer 2 in synchronization with a sampling clock from the clock control circuit 18. To generate digital pixel data (DIG2-R, DIG2-G, DIG2-B). The clock control circuit 18 switches the frequency of the sampling clock according to the display resolution of the liquid crystal panel 21, as in the first embodiment.

For example, when setting the display resolution of the XGA standard liquid crystal panel 21 to the display resolution of the VGA standard, the digital pixel data is continuously enlarged by 4.66 times for four pixels, and then one pixel is set to 1.
Set the sampling clock frequency to magnify 33 times.

FIG. 6 is a timing chart of FIG. FIG.
As shown in FIG. 6, after the data (DIG2-R, DIG2-G, DIG2-B) sampled by the sampling circuit 19 is stored in the first memory 13 as in the first embodiment, The luminance is converted by the data operation circuit 14 and stored in the second memory 15. The liquid crystal module 16 has a second memory 15
Is supplied.

As described above, when digital pixel data is supplied from the personal computer 2 to the liquid crystal display device 1a, the process of A / D conversion in the liquid crystal display device 1a becomes unnecessary. Can also simplify the configuration. Further, by adjusting the frequency of the sampling clock supplied to the sampling circuit 19, the enlargement ratio of the pixel data corresponding to each of two adjacent pixels can be set to less than twice.
1 reduces the variation in the enlargement ratio of the image data in the horizontal direction.

In the above-described embodiments, an example has been described in which the XGA standard liquid crystal panel 21 is set to the display resolution of the VGA standard or the SVGA standard, but other standards (for example, SXGA or SV)
GA etc.) when changing the display resolution of the LCD panel,
The present invention is applicable.

In each of the embodiments described above, the example in which the data operation circuit 14 for adjusting the brightness is provided has been described. However, the data operation circuit 14 may be omitted. in this case,
Some differences in line width and luminance between pixels occur.
Since the memory 15 is unnecessary, the configuration in the liquid crystal display device 1 can be simplified.

Further, in each of the above-described embodiments, an example has been described in which pixel data from the personal computer 2 is enlarged at two different enlargement ratios. However, the pixel data may be enlarged at three or more different enlargement ratios.

The image display device according to the present invention is applicable not only to the above-described liquid crystal display device but also to various display devices such as a plasma display device.

[0046]

As described above in detail, according to the present invention, the ratio of the enlargement ratio of each pixel data corresponding to each of two pixels adjacent in the direction in which the signal lines are arranged is less than twice. In addition, since each of the pixel data is enlarged according to the set display resolution, variation in the enlargement ratio of the pixel data between adjacent pixels is reduced. Therefore, even if the display resolution of the pixel display unit is changed, the display image is not distorted.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a first embodiment of a liquid crystal display device.

FIG. 2 is a block diagram showing a detailed configuration of a liquid crystal module.

FIG. 3 is a view for explaining a method of switching the display resolution in the first embodiment.

FIG. 4 is an operation timing chart of each unit of the liquid crystal display device according to the first embodiment.

FIG. 5 is a schematic block diagram of a second embodiment of the liquid crystal display device.

FIG. 6 is an operation timing chart of each unit of the liquid crystal display device according to the second embodiment.

FIG. 7 is a diagram illustrating a conventional method of enlarging pixels.

[Description of Signs] 1, 1a Liquid crystal display device 2 Personal computer 11 Signal amplification circuit 12 A / D conversion circuit 13 First memory 14 Data operation circuit 15 Second memory 16 Liquid crystal module 17 Display mode discrimination circuit 18 Clock control circuit Reference Signs List 21 liquid crystal panel 22 signal line driving circuit 23 scanning line driving circuit 24 liquid crystal controller

Claims (9)

[Claims] A display panel including an effective display area including a plurality of horizontal pixel lines in which a plurality of display pixels are arranged; and image data in each of the display pixels in the horizontal pixel lines of the display panel. A display panel driving circuit that supplies a voltage corresponding to the display pixel driving circuit, and an image data generating circuit that generates image data corresponding to the display pixel based on an input image signal and supplies the image data to the display panel driving circuit. In the image display device, the image data generating circuit expands each of the image signals corresponding to some display pixels constituting the horizontal pixel line at a first ratio in a time axis direction, and The image signals corresponding to at least some of the display pixels in the horizontal pixel line other than the display pixels are enlarged at a second ratio larger than the first ratio in a time axis direction. Includes data expansion means for generating serial image data, the image display device the second ratio is characterized in that it is set to less than the first ratio. 2. The display pixel of each of the horizontal pixel lines,
Red, blue, and green display pixels are used as a repetition unit, and the data enlargement unit sets the first and second ratios so that the pixel signal is enlarged in a time axis direction in a unit different from the repetition unit. The image display device according to claim 1, wherein: 3. The image data generating circuit according to claim 1, further comprising: a luminance correcting unit configured to correct the luminance of the image data based on a difference between the enlargement ratios of the display pixels of the respective colors having different enlargement ratios. 3. The image display device according to 2. 4. A pixel display unit on which a plurality of signal lines and scanning lines are arranged; a signal line driving circuit for supplying pixel data to each of the signal lines at a predetermined timing; and a scanning line for driving the scanning lines A display resolution setting means for setting a display resolution of the pixel display unit; and an enlargement of each pixel data corresponding to each of two pixels adjacent in the direction in which the signal lines are arranged. Pixel data enlarging means for enlarging each of the pixel data in accordance with the set display resolution so that the ratio of the ratio is less than twice. To
An image display device for supplying a signal to a corresponding signal line. 5. Each of said pixel data is constituted by a plurality of color data for color display, and said pixel data enlarging means sets an enlarging ratio individually for each of said color data to enlarge the pixel data. The image display device according to claim 4, wherein: 6. A luminance adjustment unit for adjusting the luminance of the pixel data enlarged by the pixel data enlarging means so that the luminance difference of each color data constituting the pixel data does not change before and after the enlargement of the pixel data. The image display device according to claim 4, further comprising a unit, wherein the signal line driving circuit supplies the pixel data whose luminance has been adjusted by the luminance adjusting unit to a corresponding signal line. 7. The display resolution setting means sets a display resolution of the pixel display section in accordance with a frequency of a clock synchronized with analog pixel data supplied from the outside. 7. The apparatus according to claim 6, wherein the analog pixel data is sampled by a sampling clock corresponding to a display resolution of the unit and converted into digital pixel data, and the luminance adjustment unit performs luminance adjustment based on the digital pixel data. An image display device according to claim 1. 8. A storage device, comprising: first storage means for storing pixel data expanded by the pixel data expansion means; and second storage means for storing pixel data subjected to luminance adjustment by the luminance adjustment means. The brightness adjustment unit performs brightness adjustment based on the pixel data stored in the first storage unit, and the signal line driving circuit transfers the pixel data stored in the second storage unit to a corresponding signal line. The image display device according to claim 6, wherein the image is supplied. 9. A method of driving an image display device including a pixel display unit on which a plurality of signal lines and scanning lines are arranged, wherein each pixel data corresponding to each of two pixels adjacent in the direction in which the signal lines are arranged. An image characterized by enlarging each of the pixel data in accordance with the display resolution of the pixel display unit such that the ratio of the enlarging ratio becomes less than twice, and supplying the enlarged pixel data to a corresponding signal line. A method for driving a display device.