JP2000194310A - Method and circuit for adjusting video signals of matrix type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and accurately adjust a black level and a gain. SOLUTION: When fundamental waveforms are inputted as the video signals for black level and gain adjustments, adjustment signal generating circuits 30R, 30G and 30B set a prescribed gradation level of the signals as a threshold value, obtain a first region, in which the level is more than the value, and a second region, in which the level is less than the value, reset these levels as mutually different certain gradation levels and outputs these levels as adjustment signals for black level and gain adjustments. Then, black level/gain adjusting circuits 10R, 10G and 10B are adjusted so that no color bar is generated on the screen of a display panel 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel display (PDP), a field emission display (FED), a digital micromirror device (DMD), and an electronic device for displaying an image with digitally limited intermediate gradation. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal adjustment circuit and an adjustment method for a matrix display device used in a luminescence display device (EL) and the like, and in particular, to a video signal adjustment of a matrix display device capable of easily and accurately adjusting a black level and a gain. Circuits and methods.

[0002]

2. Description of the Related Art Among matrix type display devices for displaying video signals, for example, a PDP which divides one field into a plurality of subfields and displays gradations, an EL and an FED which performs gradation display by PWM modulation, and the like. In the display device,
Depending on the driving method, an image can be expressed only with a digitally limited number of gradations.

[0003] In television broadcasting and the like in which the receiver is assumed to be a CRT display device using a cathode ray tube (CRT), gamma correction is performed in advance on the transmission side, and the inverse gamma characteristic of the receiver itself and In addition, a linear luminance characteristic is obtained. However, in the matrix type display device as described above, unlike the CRT display device,
The image is displayed with a luminance characteristic that is almost proportional to the gradation characteristic of the input video signal, that is, a linear characteristic.

Accordingly, in a matrix type display device for digitally displaying an image, it is necessary to display an image with the same gradation characteristics as in the case of displaying an image on a CRT display device that is commonly used. The image is displayed after performing inverse gamma correction to the power and returning to a linear gradation characteristic.

[0005]

However, for example, each of the digitally converted R (red), G (green), and B (blue) video signals is subjected to inverse gamma correction and displayed on the matrix type display device. Then, in particular, the number of gradations in the low luminance region is impaired, and the continuity of gradations is lost. in this case,
If the black level and the gain of each video signal are not relatively accurately adjusted for each of the R, G, and B video signals, for example, when a ramp waveform signal is input, a vertical color bar is displayed in a low luminance area. However, there is a problem that image quality disturbance that is visually recognized occurs.

[0006] When such image quality interference occurs, in particular, 1
In a PDP that displays an image by dividing a field into a plurality of subfields having different weights of light emission amounts, the probability of image quality disturbance generally having a pseudo contour of color increases. It will be noticeable. This tendency is a problem that is more or less seen in other matrix type display devices.

In particular, in the case of a PDP, since the luminance difference at each gradation step at a low gradation level is large, the black level (gradation level viewed from the pedestal level) is R,
If any one of the G and B video signals is slightly different, the above-mentioned color bar is generated. Further, even if the black level is accurately adjusted, the gain adjustment is R,
If any one of the G and B video signals is slightly different, a color bar is similarly generated. Therefore, a video signal adjustment circuit and method capable of simply and accurately adjusting a black level and a gain have been desired.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and a video signal adjusting circuit and method of a matrix type display device capable of easily and accurately adjusting a black level and a gain of an input video signal. The purpose is to provide.

[0009]

According to the present invention, there is provided a matrix type display device having a black level adjusting circuit for adjusting the black level of an input video signal. In the video signal adjustment circuit, when a basic waveform for black level adjustment is input as the video signal, a predetermined gradation level of the video signal as a threshold,
The video signal is converted to a first signal having a gradation level equal to or higher than the threshold value.
And an adjustment signal generation circuit that outputs the adjustment signal for adjusting the black level by re-setting as a constant gradation level different from each other, and a second area below the threshold. A video signal adjustment circuit for a matrix type display device, wherein the video signal adjustment circuit is provided at a stage subsequent to the black level adjustment circuit, and (2) a gain adjustment circuit for adjusting a gain of an input video signal is provided. In the video signal adjustment circuit of the matrix type display device, when a basic waveform for gain adjustment is input as the video signal, a predetermined gradation level of the video signal as a threshold,
The video signal is converted to a first signal having a gradation level equal to or higher than the threshold value.
And an adjustment signal generation circuit that outputs as an adjustment signal for gain adjustment by dividing the area into a second area smaller than the threshold and a second area that is different from each other. A video signal adjustment circuit for a matrix type display device provided at a stage subsequent to the gain adjustment circuit; and (3) a black level adjustment circuit for adjusting a black level of an input video signal; A video signal adjustment circuit for a matrix type display device, comprising: a gain adjustment circuit for adjusting a gain of an input video signal, wherein a black level and a basic waveform for gain adjustment are input as the video signal; , The first threshold value is set on the low gradation level side, and the second threshold value is set on the high gradation level side.
A first region including a region where the gradation level is lower than the first threshold value and a region where the gradation level is higher than the second threshold value; Before the first
Is adjusted to a black level and a gain adjustment signal by re-setting to a second region which is equal to or more than the threshold value and is less than the second threshold value and is set again as constant gradation levels different from each other. A video signal adjustment circuit for a matrix type display device, characterized in that an adjustment signal generation circuit for outputting the image signal is provided at a stage subsequent to the black level adjustment circuit and the gain adjustment circuit.

(4) In a video signal adjusting method for a matrix type display device provided with a plurality of black level adjusting circuits for adjusting the black levels of a plurality of input video signals, the video signal is adjusted for black level. And a predetermined level of the video signal is set as a threshold value in a subsequent stage of the black level adjustment circuit, and the video signal is converted into a first region having a gray level of the threshold value or more. And a second area smaller than the threshold value, and by resetting them as constant gray levels different from each other, the signals are supplied to the display unit as adjustment signals for adjusting the black level, and are supplied to the display unit. Any one of the plurality of black level adjustment circuits may be used to adjust the black level of any of the plurality of video signals so that an error image indicating a shift in the black level does not appear in the displayed image of the adjustment signal. (5) A video signal of a matrix type display device provided with a plurality of gain adjustment circuits for adjusting the gains of a plurality of input video signals. In the adjustment method, a basic waveform for gain adjustment is input as the video signal, and a predetermined gradation level of the video signal is set as a threshold at a subsequent stage of the gain adjustment circuit, and the video signal is converted to a gradation level. Is divided into a first region equal to or larger than the threshold value and a second region smaller than the threshold value, and are reset as constant gradation levels different from each other, thereby providing an adjustment signal for gain adjustment. The display image of the adjustment signal supplied to the display unit and displayed on the display unit,
A video signal adjusting method for a matrix type display device, wherein any one of the plurality of video signals is adjusted by any one of the plurality of gain adjusting circuits so that an error image indicating a shift in gain does not appear. Offer to,
(6) A matrix type display device comprising: a plurality of black level adjustment circuits for adjusting the black levels of a plurality of input video signals; and a plurality of gain adjustment circuits for adjusting the gains of the plurality of input video signals. In the video signal adjustment method of
A black level and a basic waveform for gain adjustment are input as the video signal, and a first threshold value is set at a lower gradation level side of the video signal at a stage subsequent to the black level adjustment circuit and the gain adjustment circuit. A second threshold value is provided on the high gradation level side, and the video signal is divided into a first region including a region where the gradation level is lower than the first threshold value and a region where the gradation level is higher than the second threshold value. By dividing the region into a region and a second region where the gradation level is equal to or higher than the first threshold value and lower than the second threshold value, and reset as constant gradation levels different from each other, The plurality of signals are supplied to a display unit as adjustment signals for level and gain adjustment, and an error image representing a shift in black level and gain does not appear in a display image of the adjustment signal displayed on the display unit. Black level adjustment circuit A matrix-type display for adjusting any one of the plurality of video signals by adjusting any one of the plurality of video signals, and adjusting any one of the plurality of video signals by any one of the plurality of gain adjustment circuits. A method for adjusting a video signal of an apparatus is provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a video signal adjusting circuit and method of a matrix type display device according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of a video signal adjusting circuit of a matrix type display device according to the present invention, and FIG. 2 is an adjusting signal generating circuit 30R, 30G, 30 in FIG.
FIG. 3 is a block diagram showing an example of a specific configuration of B, FIG. 3 is a diagram showing a display image when a ramp waveform signal is input to the video signal adjustment circuit of the matrix type display device of the present invention, and FIG. FIG. 5 is a diagram showing an example of a display image when a black level is adjusted by a video signal adjusting circuit and method of a display device, FIG. 5 is a diagram showing an example of a state where the black level is shifted, and FIG. 6 is a matrix type display of the present invention. FIG. 7 is a diagram showing an example of a display image display when the gain is adjusted by the video signal adjusting circuit and method of the device, FIG. 7 is a diagram showing an example of a state where the gain is shifted, and FIG. FIG. 9 is a diagram showing an example of a display image when a black level and a gain are adjusted together by a video signal adjustment circuit and method. FIG. 9 is a diagram showing a base used in a video signal adjustment circuit and method of a matrix type display device of the present invention. It is a waveform diagram showing another example of the waveform.

FIG. 1 shows an example of the overall configuration of a matrix type display device including a video signal adjusting circuit according to the present invention.
Here, a case of a PDP is shown as an example of a matrix display device. In FIG. 1, three input video signals of an R signal, a G signal, and a B signal are input to a black level / gain adjustment unit 1. Black level / gain adjustment unit 1
Is a black level for adjusting the black level and gain of the R signal.
It comprises a gain adjustment circuit 10R, a black level / gain adjustment circuit 10G for adjusting the black level and gain of the G signal, and a black level / gain adjustment circuit 10B for adjusting the black level and gain of the B signal. Black level / gain adjustment circuit 10
R, 10G, and 10B are collectively called a black level / gain adjustment circuit 10.

The black level / gain adjustment circuit 10 adjusts the pedestal level and the gain of the input video signal (R, G, B signals) in consideration of the input voltage range of the A / D converter 2 at the next stage. , A / D converter 2. The adjustment of the black level and the gain in the black level / gain adjustment circuit 10 may be performed by digitally sending a control signal from the outside and performing D / A conversion on the control signal, or controlling the analog by a variable resistor or the like. May be controlled.

The A / D converter 2 includes an A / D converter 20R for converting an analog R signal input from the black level / gain adjustment circuit 10R into a digital signal, and a black level / gain adjustment circuit 10G. A / D converter 2 for converting a G signal, which is an input analog signal, into a digital signal
0G, and an A / D converter 20B that converts an analog B signal input from the black level / gain adjustment circuit 10B into a digital signal. A / D converter 20R,
20G and 20B are collectively referred to as an A / D converter 20. The A / D converter 20 converts the R, G, B signals into digital signals and inputs the digital signals to the video signal processing unit 3.

The video signal processing unit 3 receives the input R, G,
The B signal is subjected to various signal processing and input to the inverse gamma correction unit 4. That is, the video signal processing unit 3 performs pixel conversion in accordance with the number of display pixels of the display panel 5, performs signal processing for improving display image quality, and the like. Further, the video signal processing unit 3 includes an adjustment signal generation circuit 30 which is a main part of the present invention.
R, 30G, and 30B. When adjusting the black levels and gains of the R, G, and B signals, the adjustment signal generation circuits 30R, 30G, and 30B generate adjustment signals for adjusting the black levels and gains. The adjustment signal generation circuits 30R, 30G, and 30B are collectively referred to as an adjustment signal generation circuit 30. The specific configuration and operation of the adjustment signal generation circuit 30 will be described later in detail.

The reverse gamma correction section 4 includes a reverse gamma correction circuit 40R for performing reverse gamma correction on the R signal, a reverse gamma correction circuit 40G for performing reverse gamma correction on the G signal, and B
Inverse gamma correction circuit 40 for performing inverse gamma correction on a signal
B. Inverse gamma correction circuits 40R, 40G, 40
B is generically called an inverse gamma correction circuit 40.
The inverse gamma correction circuit 40 performs inverse gamma correction of the same characteristics on the R, G, and B signals, and inputs the signals to the display panel 5.

The display panel 5 comprises a so-called panel body and a drive circuit for driving the panel body. The R, G, and B signals input to the display panel 5 are subjected to various driving processes such as subfield processing, and are displayed on the screen of the display panel 5.

Here, the specific configuration and operation of the adjustment signal generation circuit 30 will be described with reference to FIG. In FIG. 2, any one of R, G, and B signals is input to threshold level setting section 301 as an input signal. The threshold level setting section 301 sets a predetermined threshold value for the gradation level of the input signal, and the threshold level setting section 301 sets the threshold level of the input signal equal to or higher than the threshold gradation level. In the case of one area, the input signal is input to the first area gradation level resetting section 302, and in the case of the second area smaller than the threshold gradation, the input signal is input to the second area gradation level. Input to the resetting unit 303. The threshold value in the threshold level setting unit 301 is set at an arbitrary position on the low gradation level side or the high gradation level side. Note that this is an operation in the case where there is one threshold, and an operation in the case where there are two thresholds will be described later.

The first area gray level resetting section 302 and the second area gray level resetting section 303 respectively convert the input signals of the first area and the second area to new fixed gray levels. It is reset and input to the area combining unit 304. At this time, the gray level reset by the first area gray level resetting unit 302 and the second area gray level resetting unit 303 is set to a value that is significantly different between the first area and the second area. Set. For example, when the threshold level is set to the lower gradation level, the gradation level of the first area is set to a large value,
It is preferable to set the gradation level of the region to 0. Conversely, when the threshold level is set to the higher gradation level, it is preferable to set the gradation level of the first region to 0 and the gradation level of the second region to a larger value.

The area synthesizing section 304 synthesizes the signal of the first area and the signal of the second area, and outputs it as an adjustment signal for adjusting the black level and gain of the R, G, B signals.

An example of a method of adjusting a black level and a gain using the above-described adjustment signal generation circuit 30 will be described.
FIG. 3 shows a display image displayed on the display panel 5 when a ramp waveform signal, which is an example of a basic waveform for black level and gain adjustment, is input as the R, G, and B signals in FIG. I have. Here, a case is shown in which the black levels and gains of the R, G, and B signals completely match. Since the ramp waveform signal has a linear gradation characteristic, a PDP that performs inverse gamma correction by the inverse gamma correction unit 4 and displays the image as it is displayed on the display panel 5 as shown in FIG. Is a step-like waveform for each gray level (including white and black). At this time, the step waveform is
As the gradation becomes closer to black, the gradation becomes insufficient, so that the width of the stairs becomes larger. That is, the width of the left stage is larger than the width of the right stage in FIG.

Such discontinuity due to the boundary of the step-like waveform can be reduced by performing multi-gradation processing such as dithering and error diffusion in the video signal processing unit 3, the display panel 5, and the like. . However, when adjusting the black level and gain using the adjustment signal generation circuit 30, it is easier to adjust without performing the above-described multi-gradation processing. It is preferable to remove the chemical treatment. In other words, it is better for the boundary of the step-like waveform shown in FIG. 3 to be visually clear.

As described as a conventional problem, if any one of the input R, G, and B signals has a different black level and gain, a vertical color bar (error image) is generated. Will occur. If the black level and the gain are different at a certain gradation, a color bar is generated rightward or leftward from the gradation. Therefore, if the black level and the gain are different in a plurality of gradations, the color bars in the vertical direction are mixed at a plurality of positions in the horizontal direction, and it is difficult to adjust the black level and the gain in the related art. there were.

In the present invention, the black level and gain of the R, G, and B signals are adjusted using the display characteristics of the display panel 5. When a ramp waveform signal is input as the R, G, and B signals, it is necessary that after adjusting the black level and the gain by the adjustment method of the present invention, a gray step-like waveform as shown in FIG. 3 be obtained. Therefore, the characteristics of the inverse gamma correction by the inverse gamma correction circuits 40R, 40G, and 40B are all the same.

As described above, a ramp waveform signal is input as a basic waveform for black level and gain adjustment, and a specific adjustment method for black level and gain adjustment will be described in order. First, when adjusting the black level, the threshold level setting unit 301 in the adjustment signal generation circuit 30 sets a predetermined gray level (for example, gray level 3) on the low gray level level as a threshold value. I do. As an example, in the first area gray level resetting section 302, the first area having the threshold level 3 or more is set to the gray level 200, and in the second area gray level resetting section 303, the threshold level 3 is set. Less than second
The area is reset to gradation 0. Here, 256 gradations are taken as an example.

As described above, when the gradation levels of the R, G, and B signals are reset to two different constant gradation levels in the two regions, as shown in FIG. The above-described first region is substantially white, and the second region below the threshold level 3 on the left side in the drawing is black. FIG. 4 shows a state where there is no variation in the black levels of the R, G, and B signals. This state is a display image obtained after adjusting the black levels of the R, G, and B signals. As described later, the display image shown in FIG.
Adjust the black level of the signal.

FIG. 5 shows a state where the black levels of the R, G and B signals vary. In FIG. 5, (A)
As shown in the figure, the pedestal level of the G signal is equal to the voltage level of gradation 0 of the A / D converter 20, the black level of the R signal is shifted in the white level direction, and the black level of the B signal is shifted in the pedestal level direction. It shows the state where it was turned on.

The threshold level of the gradation 3 for the G signal is located on the boundary between the regions in the display panel 5 in FIG. On the other hand, since the black level of the R signal is shifted in the white level direction, the threshold level of the gradation 3 for the R signal is
Since the black level of the B signal is shifted in the pedestal level direction on the boundary line between the areas in FIG. 5B, the threshold level of the gray level 3 for the B signal is
On the display panel 5, it is located on the boundary between the regions in FIG.

In the example of FIG. 5, only the R signal in the leftward direction in the drawing is defined by the boundary between the regions in FIG. A red color bar is generated because the threshold level is 3 or more, and a magenta color bar is generated in the rightward direction in the figure because the R signal and the B signal are at the threshold level 3 or more. That is, when the black levels of the R, G, and B signals vary, as shown in FIG.
If the black level deviates in the white level direction from the threshold value set in the above, a color bar is generated to the left on the screen of the display panel 5, and if the black level deviates in the pedestal level direction, the display panel 5, a color bar is generated in the right direction on the screen.

Referring again to FIG. 5, in the region, R, G, B
Since all of the signals are below the threshold level, a black bar of gradation 0 is obtained. In the region, since all of the R, G, and B signals are at or above the threshold level, the bar becomes a substantially white bar with a gradation of 200. Therefore, in the example of FIG. 5, the four types of color bars shown in the area 1 are displayed on the screen of the display panel 5.

In this case, the black level / gain adjusting circuits 10R, 10R are moved so that the boundary between the R signal and the B signal is moved to the boundary between the G signals.
10B adjusts the black levels of the R and B signals. R,
The black levels of all the input signals of the G and B signals are matched, and only the area of the gray scale 0 and the area of the gray scale 200, that is,
The adjustment may be made while looking at the screen so that the state as shown in FIG. 4 is obtained.

In the example of FIG. 5, the black levels of the R and B signals are adjusted with reference to the G signal whose gradation 0 is the pedestal level. However, the present invention is not limited to this. Since the characteristics of the display image on the display panel 5 also change depending on the characteristics of the inverse gamma correction, etc., the display image including the moving image is actually displayed, and based on the result of thorough examination, which gradation is located at the pedestal level position What is necessary is just to determine whether to adjust.

When the above adjustment is performed in the manufacturing process of the matrix type display device, before the black level adjustment according to the present invention, the pedestal level of each input signal is input to the A / D converter 20 before being adjusted. The input voltage need not be adjusted in advance. If the same device is used as a signal generator for generating the input ramp waveform signal and the input mode of a certain fixed synchronization frequency such as NTSC or HDTV is fixed, the ramp waveform signal is displayed on the display panel 5. At some threshold level, the position of the border on the screen is
Determined by itself.

Therefore, the scale for displaying in advance how many centimeters or the number of rows of dots are from the left on the screen as a boundary line between the gradation 0 and the gradation 200 so that the operator can easily understand the scale. If displayed, even if the pedestal level is not adjusted in advance, it is possible to eliminate variations in the black levels of the R, G, and B signals during manufacturing. Also, in all the display panels 5, it is possible to eliminate the variation in the black level between the display panels 5.

The threshold value set by the threshold level setting unit 301 may be set to any gradation, but it is better to set the threshold value on the lower gradation level side than the central level of the gradation. This is to make it easy to adjust both the black level and the gain when adjusting the black level and the gain in one screen, as described later.

Next, when adjusting the gain, the threshold level setting section 301 in the adjustment signal generation circuit 30 sets a predetermined gradation (for example, gradation 230) on the high gradation level side.
Is set as the threshold. And, as an example, the first
In the area gradation level resetting section 302, the first area having the threshold level 230 or higher is set to the gradation 0, and in the second area gradation level resetting section 303, the second area having the threshold level 230 or less is set to the gradation 0. The key is reset to 200. Here, 256 gradations are taken as an example.

As described above, when the gradation levels of the R, G, and B signals are reset to different constant gradation levels in the two regions, as shown in FIG. The first region described above is black, and the second region below the threshold level 230 on the left side in the drawing is substantially white.
FIG. 6 shows a state where there is no variation in the gain of the R, G, B signals. This state is a display image obtained after adjusting the gains of the R, G, and B signals. As will be described later, R, G, and B signals are displayed so that the display image shown in FIG.
Adjust the gain of the G and B signals.

FIG. 7 shows a state where the gains of the R, G and B signals vary. In FIG. 7, as shown in FIG. 7A, the gain of the G signal is within the range of the input voltage level of the A / D converter 20, the gain of the R signal is shifted in the direction of the large gain, and the gain of the B signal is reduced. This shows a state shifted in the small gain direction. Here, it is assumed that the black levels of the R, G, and B signals have been accurately adjusted.

The threshold level of the gray scale 230 for the G signal is located on the display panel 5 on the boundary between the regions in FIG. On the other hand, since the gain of the R signal is shifted in the large gain direction, the threshold level of the gradation 230 with respect to the R signal on the display panel 5 is on the boundary line between the regions in FIG. , And the gain of the B signal is shifted in the small gain direction, so that the threshold level of the gradation 230 for the B signal is on the boundary line between the regions in FIG. Located in.

In the example of FIG. 7, the original threshold level 23
In the region on the left side of the drawing with respect to the boundary between the regions shown in FIG.
Since the signal is below the threshold level 230, a cyan color bar (error image) is generated. In the rightward direction in the drawing, only the B signal is below the threshold level 230, so the blue color bar is Image) occurs. That is, R,
When the gains of the G and B signals vary, as shown in FIG. 6, if the gain is shifted in the large gain direction from the threshold value set by the threshold level setting unit 301, the display panel 5 A color bar is generated leftward on the screen, and if the gain is shifted in the small gain direction, a color bar is generated rightward on the screen of the display panel 5.

Referring back to FIG. 7, in the area, R, G, B
Since all of the signals are below the threshold level,
0 is almost a white bar. In the region, since all of the R, G, and B signals are at or above the threshold level, a black bar of gradation 0 is obtained. Therefore, in the example of FIG. 7, four types of color bars shown in the area to are displayed on the screen of the display panel 5.

In this case, the black level / gain adjustment circuits 10R, 10R are moved so that the boundary between the R signal and the B signal is moved to the boundary between the regions as the boundary between the G signals.
10B adjusts the gains of the R and B signals. R,
The gains of all the input signals of the G and B signals are made to match each other, and only the area of the gradation 200 and the area of the gradation 0, that is,
The adjustment may be made while looking at the screen so that the state as shown in FIG. 6 is obtained.

In the example of FIG. 7, R, R,
Although the gain of the B signal is adjusted, the present invention is not limited to this. The characteristics of the display image on the display panel 5 also change depending on the characteristics of the inverse gamma correction, etc.
A display image including a moving image may be actually displayed, and the minimum level and the maximum level of the gain may be determined based on the result of sufficient consideration.

In the case where the above adjustment is performed in the manufacturing process of the matrix type display device, before the gain adjustment according to the present invention, the input voltage of the gain is input to the A / D converter 20 before being input to the A / D converter 20. Need not be adjusted in advance. If the same device is used as a signal generator for generating the input ramp waveform signal and the input mode of a certain fixed synchronization frequency such as NTSC or HDTV is fixed, the ramp waveform signal is displayed on the display panel 5. At this time, the position of the boundary line on the screen at a certain threshold level is naturally determined.

Therefore, a scale for displaying in advance how many centimeters or the number of rows of dots are from the left on the screen so that the boundary line between the gradation 0 and the gradation 200 is a dot on the screen is set so that the operator can easily understand it. If displayed, it is possible to eliminate variations in the gain of the R, G, and B signals during manufacturing without adjusting the gain in advance. In addition, in all the display panels 5, it is possible to eliminate the variation in the gain between the display panels 5.

The threshold value set by the threshold level setting section 301 may be set to any gradation. However, when adjusting the gain, contrary to the above-described black level adjustment,
It is better to be provided on the higher gradation level side than on the central level of the gradation. This is because the variation in the gain of the R, G, and B signals appears more remarkably as a color bar on the screen when the threshold value is provided on the high gradation level side. Separating the threshold value for adjusting the black level and the threshold value for adjusting the gain between the low gradation level side and the high gradation level side means that the black level and the gain described later are set to 1 It is also preferable to make adjustments on the screen.

Further, a method of adjusting the black level and the gain together on one screen will be described. When adjusting the black level and the gain together, the threshold level setting unit 301 in the adjustment signal generation circuit 30 sets the predetermined gray level (for example, gray level 3) on the low gray level level to the first level. And a predetermined gradation on the high gradation level side (for example, gradation 230)
Is set as the second threshold value. As an example, in the first area gradation level resetting section 302, the first area having the threshold level lower than 3 and the threshold level 230 or higher is set to gradation 0, and the second area gradation level resetting section 303 is set. , The second region having the threshold level 3 or more and less than the threshold level 230 is reset to the gradation 200.

Here, two regions in the first region,
That is, although the gradation level is the same in the region with the threshold level lower than 3 and in the region with the threshold level 230 or higher, the gradation levels may be different from each other. In this case, it is sufficient to provide three gradation level resetting units for separately resetting the gradation levels of the three regions of the two regions and the second region in the first region. It is sufficient that at least the gradation level of the first region and the gradation level of the second region are different and the boundary between the two locations can be visually determined.

As described above, the gradation levels of the R, G, and B signals are divided into three regions, and the gradation levels of the first region at the left and right ends of the screen and the second region at the center are re-set to different constant gradation levels. When set, as shown in FIG. 8, the first threshold value 230 or more on the right side in the figure and the first threshold value less than the threshold level 3 on the left side in the figure are set.
In the region, the color becomes black, and in the second region having the threshold level of 3 or more and less than 230 at the center in the left-right direction in the drawing, it becomes almost white.
FIG. 8 shows a state where there is no variation in the black level and the gain of the R, G, B signals. This state is
This is a display image obtained after adjusting the black levels and gains of the R, G, and B signals. In order to obtain the display image shown in FIG. , B signal black level and gain are adjusted.

The first and second threshold values set by the threshold level setting section 301 may be set to any gradation, but can be set to a lower gradation level. It is better to set the threshold value as low as possible on the gradation level side and the threshold value set on the high gradation level side as much as possible, and set the threshold values as high as possible. In this way, the color bar generated due to the variation in the gain hinders visually when adjusting the black level, and conversely, the color bar generated due to the variation in the black level causes a visual hindrance when adjusting the gain. And both the black level and the gain can be adjusted well.

In this embodiment, a ramp waveform signal is used as an input signal, but the present invention is not limited to this. When adjusting the black level and the gain together on one screen, inputting an S-shaped waveform signal as shown in FIG. 9 slightly increases the difficulty of the adjustment, but adjusts the black level and the gain on the screen. It can be performed more accurately as a position.

Similar effects can be obtained by adjusting the black level using a pedestal signal waveform. Any signal waveform may be input as a basic waveform for adjusting the black level and gain as long as the input signal can set the threshold level at which the effects of the present invention can be obtained. Any waveform in which a plurality of gradations are mixed in a range from a black level to a white level can be used as a basic waveform. If the basic waveforms are different, the adjustment signals are different, and the error images appearing on the screen are also different. In any case, make sure that no error images appear on the screen.
The black level and the gain may be adjusted.

Further, in this embodiment, as the input signal,
Although an example has been described in which the black level and the variation in gain of three video signals composed of R, G, and B signals are adjusted, the present invention can be used if the input signal is a plurality of video signals of two or more types. . In this embodiment, the black level and gain are adjusted by the black level / gain adjustment circuit 10. However, the black level adjustment circuit and the gain adjustment circuit may be separate circuits. It may be an integrated circuit that adjusts together. The present invention may be used only for adjusting the black level, or may be used only for adjusting the gain.

[0054]

As described above in detail, the video signal adjusting circuit and method of the matrix type display device according to the present invention, when a black level or a basic waveform for gain adjustment is input as a video signal, the video signal Is set as a threshold value, and the video signal is divided into a plurality of regions according to the gradation level with the threshold value as a boundary, and is reset as a constant gradation level different from each other. An adjustment signal generation circuit that outputs as an adjustment signal for adjusting the black level and gain is provided, and the black level and gain are adjusted while visually adjusting on the screen. And it can be adjusted accurately.
Further, variation between display panels can be eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating an adjustment signal generation circuit 30R, 30G,
It is a block diagram showing an example of the concrete composition of 30B.

FIG. 3 is a diagram showing a display image when a ramp waveform signal is input to a video signal adjustment circuit of the matrix type display device of the present invention.

FIG. 4 is a diagram showing an example of a display image when a black level is adjusted according to the present invention.

FIG. 5 is a diagram illustrating an example of a state in which a black level is shifted.

FIG. 6 is a diagram showing an example of a display image display when a gain is adjusted according to the present invention.

FIG. 7 is a diagram illustrating an example of a state in which the gain is shifted.

FIG. 8 is a diagram showing an example of a display image when the black level and the gain are adjusted together according to the present invention.

FIG. 9 is a waveform chart showing another example of the basic waveform used in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 black level / gain adjustment unit 2 A / D conversion unit 3 video signal processing unit 4 inverse gamma correction unit 5 display panel 10R, 10G, 10B black level / gain adjustment circuit 20R, 20G, 20B A / D converter 30R, 30G , 30B adjustment signal generation circuit 40R, 40G, 40B inverse gamma correction circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/66 H04N 5/66 A 9/68 9/68 9/73 9/73 EF term (reference) 5C058 AA11 AA12 AA18 BA13 BA35 BB04 BB25 5C066 AA01 AA11 BA20 CA05 CA13 EA05 EA07 GA01 GB01 HA03 HA04 JA01 KD01 KD07 KE01 KE07 LA02 5C080 AA05 AA06 AA18 BB05 CC03 DD03 DD30 EE29 JJ09 JJ01 JJ01 JJ01 JJ09 JJ01

Claims (6)

[Claims] 1. A video signal adjustment circuit of a matrix type display device having a black level adjustment circuit for adjusting a black level of an input video signal, wherein a basic waveform for black level adjustment is input as the video signal. A predetermined gray level of the video signal as a threshold, the video signal is divided into a first area where the gray level is equal to or higher than the threshold and a second area where the gray level is lower than the threshold; An adjustment signal generation circuit for outputting as an adjustment signal for adjusting a black level by resetting each of the gray levels to a different constant gray level is provided at a subsequent stage of the black level adjustment circuit. Video signal adjustment circuit of a matrix type display device. 2. A video signal adjustment circuit of a matrix type display device comprising a gain adjustment circuit for adjusting a gain of an input video signal, wherein when a basic waveform for gain adjustment is input as the video signal, A predetermined gradation level of a signal is used as a threshold, and the video signal is divided into a first region where the gradation level is equal to or higher than the threshold and a second region where the gradation level is lower than the threshold.
A matrix characterized in that an adjustment signal generation circuit for outputting as an adjustment signal for gain adjustment by resetting each of them as a constant gradation level different from each other is provided at a subsequent stage of the gain adjustment circuit. Video signal adjustment circuit of a flat panel display device. 3. A video signal adjusting circuit for a matrix type display device, comprising: a black level adjusting circuit for adjusting a black level of an input video signal; and a gain adjusting circuit for adjusting a gain of the input video signal. When a black level and a basic waveform for gain adjustment are input as the video signal, a first threshold value is set on a low gray level level and a second threshold value is set on a high gray level level in the video signal. And providing a first area including a region where a gray level is lower than the first threshold value and a region higher than or equal to the second threshold value; It is divided into a second area which is equal to or more than the threshold value and is less than the second threshold value, and is re-set as a constant gradation level different from each other, thereby outputting as an adjustment signal for black level and gain adjustment. Adjustment signal A video signal adjustment circuit for a matrix type display device, wherein a generation circuit is provided at a stage subsequent to the black level adjustment circuit and the gain adjustment circuit. 4. A video signal adjusting method for a matrix type display device comprising a plurality of black level adjusting circuits for adjusting black levels of a plurality of input video signals, wherein a basic waveform for adjusting a black level as the video signal is provided. In a subsequent stage of the black level adjusting circuit, a predetermined gray level of the video signal is set as a threshold, and the video signal is defined as a first region having a gray level higher than the threshold. By dividing it into a second region having a value less than the threshold value and resetting it as a constant gradation level different from each other, it is supplied to the display unit as an adjustment signal for adjusting the black level, and is displayed on the display unit. Any one of the plurality of black level adjustment circuits adjusts the black level of any of the plurality of video signals so that an error image indicating a shift in the black level does not appear in the display image of the adjustment signal. Video signal adjustment method of a matrix type display device according to claim. 5. A video signal adjustment method for a matrix type display device having a plurality of gain adjustment circuits for adjusting gains of a plurality of input video signals, wherein a basic waveform for gain adjustment is input as the video signal. In a subsequent stage of the gain adjustment circuit, a predetermined gradation level of the video signal is set as a threshold, and the video signal is divided into a first region where the gradation level is equal to or more than the threshold and a region where the gradation level is lower than the threshold. By dividing into the second area and resetting as a constant gradation level different from each other, the signal is supplied to a display unit as an adjustment signal for gain adjustment, and the adjustment signal displayed on the display unit is displayed. The gain of one of the plurality of video signals is adjusted by one of the plurality of gain adjustment circuits so that an error image indicating a shift in gain does not appear in the image. Video signal adjustment method of Rikusu display device. 6. A matrix type comprising: a plurality of black level adjusting circuits for adjusting black levels of a plurality of input video signals; and a plurality of gain adjusting circuits for adjusting gains of the plurality of input video signals. In the video signal adjustment method for a display device, a basic waveform for adjusting a black level and a gain is input as the video signal, and a low gradation level side of the video signal is provided at a stage subsequent to the black level adjustment circuit and the gain adjustment circuit. A first threshold value, and a second threshold value on a high gradation level side. The video signal is divided into a region where the gradation level is less than the first threshold value and the second threshold value. A first region including the above-described regions, and a second region having a gradation level equal to or higher than the first threshold value.
The second region is smaller than the threshold value, and is re-set as a constant gradation level different from each other, so as to be supplied to a display unit as an adjustment signal for adjusting a black level and a gain. Any one of the plurality of black level adjustment circuits may be used to prevent any error image representing a shift in black level and gain from appearing in the display image of the adjustment signal displayed in the section. A video signal adjusting method for a matrix type display device, wherein a level is adjusted and any one of the plurality of video signals is adjusted by one of the plurality of gain adjusting circuits.