JP2003255886A - Display device and gradation display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide precise gradation display at low and high luminance portions of a display device which conducts the gradation display based on a plurality of subfields. <P>SOLUTION: A switching gradation determination section 8 detects the luminance distribution of one screen of a PDP 1 based on the values of video data from an A/D converting section 2 which converts analog video signals into digital video signals and discriminates to determine the luminance range that indicates the range of luminance values in the luminance distribution based on a plurality of luminance range data beforehand set and the values of the video data within the detected luminance distribution. The determinated luminance range is outputted to a data conversion section 6 which converts the video data and a subfield constituting section 9 which divides one field display interval of the PDP 1 into a plurality of subfields having different luminance ratios and the number of gradation within the determination luminance range is increased by the sections 6 and 9. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a gradation display method.

[0002]

2. Description of the Related Art Generally, a display device such as a plasma display panel (hereinafter referred to as PDP) has a plurality of row electrodes arranged for each scanning line, and a plurality of column electrodes arranged so as to intersect the row electrodes. A discharge cell corresponding to one pixel is formed at the intersection of the column electrode and the column electrode. Since the discharge cell of such a PDP has only two states, light emission and non-light emission,
By dividing the field display period (display period of one frame) into a plurality of subfields each having a different relative ratio of the lighting period (sustaining discharge period; proportional to light emission luminance), an intermediate gradation display is obtained. There is. Here, in the PDP device, when an analog video signal is input, the analog video signal is A / D converted to be converted into video data having a bit number corresponding to the number of subfields, and a corresponding pixel is appropriately selected based on the converted video data. The sub-field is turned on to display an intermediate gradation.

In the example shown in FIG. 4, two gradation bits are used for two gradations.
This is an example of displaying 56 gradations, and the lowest gradation bit (1
Bit bit) corresponds to SF8, and in the following order, 2
The gradation bit of the bit is SF7, the gradation bit of the third bit is SF6, the gradation bit of the fourth bit is SF5,
The fifth gradation bit corresponds to SF4, the sixth gradation bit corresponds to SF3, the seventh gradation bit corresponds to SF2, and the highest gradation bit (8th bit) corresponds to SF1. Correspond. In each of the sub-fields SF1 to SF8, the sustain discharge period is, for example, the relative ratio of the emission luminance (proportional to the number of emission sustaining pulses) 128, 64, 32, 1
Weighted as 6,8,4,2,1.

[0004]

As described above, in the PDP device, since the discharge cell (that is, the pixel) of the PDP has only two states of light emission and non-light emission, an intermediate gray scale is expressed. As described above, one field period is divided into a plurality of subfields, weighting is performed in each subfield in accordance with the brightness level of video data, and the corresponding pixel is caused to emit light with the number of times of light emission according to the weighting.

However, when each pixel of the PDP is caused to emit light by such a plurality of sub-fields, for example, the low luminance portion A in the input / output characteristics of the PDP shown in FIG. Since the level of the output display data is remarkably lowered and the display gradation is lowered, when the screen of the PDP is generally dark, it is impossible to identify what kind of image the image displayed on the PDP is. In addition, the screen of the PDP shows the high-intensity part B in FIG.
As described above, there is a problem that a gradation step becomes large in a bright portion, and smooth gradation display cannot be performed.

Therefore, according to the present invention, in a display device for inputting display data obtained by A / D conversion of an analog video signal and performing gradation display based on a plurality of subfields, a low luminance portion and a high luminance portion are provided. The purpose is to enable accurate gradation display in.

[0007]

In order to solve such a problem, the present invention provides a display panel including a plurality of pixels,
A sub-field configuration unit that generates a timing signal that divides a display period of one field of the display panel into a plurality of sub-fields having different luminance ratios, and an input analog video signal, video data having a bit number according to the number of sub-fields In a display device including an A / D conversion unit that performs A / D conversion and a drive unit that outputs video data to a display panel according to the timing signal and performs gradation display on the display panel, In addition to detecting the brightness distribution of one screen of the display panel, the brightness value range in the brightness distribution is determined based on a plurality of preset brightness value range data and the value of the video data in the detected brightness distribution. The determination unit that determines the brightness range that is represented, the data conversion unit that converts the video data and outputs it to the drive unit, and the brightness range that is determined by the determination unit. If you enter, it is provided with a gradation number increasing means for increasing the control data conversion unit and the subfield structure unit number of gradations in the luminance range (including the number of subfields).

In this case, the gradation number increasing means increases the number of gradations of the low luminance part and increases the number of gradations of the high luminance part when the judging section judges that the luminance range is in the low luminance range. Reduce the number of gradations. Further, the gradation number increasing means increases the number of gradations of the high-luminance portion and increases the number of gradations of the low-luminance portion when the judgment unit judges that the luminance range is in the high-luminance range. Reduce. Further, the gradation number increasing means increases the number of gradations of the middle brightness part and increases the number of gradations of the high brightness part and the low brightness part when the judgment part judges that the brightness range is in the middle brightness range. Reduce the number of gradations.

Further, the image data of the A / D conversion unit is inversely γ-corrected and is output as display data to the data conversion unit. The γ-inverse correction unit is provided, and the determination unit determines the display panel based on the value of the display data. The brightness distribution of one screen is detected. Also, the subfield configuration unit adds a subfield having a luminance ratio of 1/2 of the minimum luminance ratio to the plurality of subfields.

Further, according to the present invention, the analog video signal is converted to A /
The brightness distribution of one screen of the display panel is detected based on the value of the video data from the A / D conversion unit for D conversion, and a plurality of preset brightness value range data and the detected brightness distribution When the first step of determining a brightness range representing the range of brightness values in the brightness distribution based on the value of the video data and the brightness range determined based on the processing of the first step are input, the video data is stored. The data conversion unit for conversion and the subfield configuration unit that generates a timing signal that divides the display period of one field of the display panel into a plurality of subfields each having a different luminance ratio are controlled to increase the number of gradations in the input luminance range. And a second step of performing gradation display on the display panel.

In this case, the processing in the second step increases the number of gradations in the low brightness portion when it is determined that the brightness range is in the low brightness area based on the processing in the first step. In addition, a third step of reducing the number of gradations in the high brightness portion is included. Further, in the process in the second step, when it is determined that the brightness range is in the high brightness range based on the process in the first step, the number of gradations of the high brightness part is increased and the low brightness is increased. It includes a fourth step of reducing the number of gradations in the portion. Further, in the processing in the second step, when it is determined that the luminance range is in the medium luminance range based on the processing in the first step, the number of gradations in the medium luminance portion is increased and the high luminance is increased. The method includes a fifth step of reducing the number of gradations of the portion and the low luminance portion. It also has a sixth step of γ-inversely correcting the video data of the A / D conversion section and outputting it as display data to the data conversion section. The processing in the first step is performed based on the value of the display data. The seventh step of detecting the luminance distribution of one screen of the panel is included.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a display device according to the present invention. This display device has a plasma display panel (hereinafter referred to as PDP) 1 as shown in FIG.
An A / D conversion unit 2, an input data processing unit 3, a sync separation unit 7, a γ inverse correction unit 4, a frame memory 5, a switching gradation determination unit 8, a subfield configuration unit 9, The input data processing unit 3 includes a system clock generation unit 10, a driving unit 11, and a sustain pulse number control unit 12.
γ inverse correction unit 4, frame memory 5, and data conversion unit 6
Consists of.

Here, the A / D converter 2 converts the analog video signal a into a digital signal. Further, the sync separator 7 separates the sync signal from the input analog video signal a. In addition, the γ inverse correction unit 4 that constitutes the input data processing unit 3 uses the A / D conversion unit 2 for A / D conversion.
Γ inverse correction is performed on the changed digital signal. Further, the frame memory 5 constituting the input data processing unit 3 stores the data for which the γ inverse correction has been performed by the γ inverse correction unit 4 for one frame. The switching gradation determination unit 8 also has statistical characteristics of data for one screen (one frame) of the PDP 1 that has been γ-inversely corrected by the γ-inverse correction unit 4 in order to switch the gradation characteristics according to the gradation range. And the switching gradation is determined. Further, the sub-field configuration unit 9 uses the vertical sync signal separated by the sync separation unit 7 as a reference, and the switching gradation determined by the switching gradation determination unit 8,
The internal clock generated by the system clock generator 10 is used to determine the light emission time according to the relative ratio of the luminance of each subfield, and to determine the timing from the first subfield SF1 to the nth subfield SFn. is there.

Further, the data converting section 6 constituting the input data processing section 3 has a gradation range corresponding to the switching gradation determined by the switching gradation determining section 8 for the display data stored in the frame memory 5. A specific process is performed therein and the process result is output to the drive unit 11. The drive unit 11 includes the data conversion unit 6
Display data output from the subfield configuration unit 9
To drive the PDP1 based on the timing signal from No. 1 and the sustaining pulse number set by the sustaining pulse number control unit 12, and repeat the light emitting operation of the PDP1 from the first subfield SF1 to the nth subfield SFn. Is.

FIG. 2 is a diagram showing an arrangement structure of subfields applied to the PDP 1. In FIG. 2, the time for one frame is 1/60 second, and the time for one frame is
Each is divided into nine subfields from a first subfield SF1 to a ninth subfield SF9, each of which includes a scanning period and a sustaining discharge period (sustaining emission period).

Here, in the scanning period of the first subfield SF1, writing is performed in each pixel of PDP1 based on the display data of the most significant bit from the frame memory 8.
When the writing of the entire screen of PDP1 is completed, the sustaining discharge pulse is applied to the entire screen of PDP1 during the sustaining discharge period to cause only the writing pixel to emit light. Next, in the scanning period of the second subfield SF2, the PDP is based on the display data of the bit next to the most significant bit from the frame memory 8.
Writing is performed on each pixel of 1. When the writing of the entire screen of PDP1 is completed, the PDP is
The sustain discharge pulse is applied to the entire screen of No. 1 to cause only the writing pixel to emit light. After that, the third subfield SF
Similarly, from the third to the ninth subfield SF9, writing to each pixel of PDP1 and application of a sustain discharge pulse to the entire screen of PDP1 are performed.

In the sustain discharge period of each of the subfields SF1 to SF9, sufficient luminance is obtained and the relative ratio of the luminance in each of the subfields SF1 to SF9 is 2 ^n-1 :
In order to make 2 ^n-2 : ...: 2: 1, generally, as shown in FIG. 2, 256 times in the subfield SF1, 128 times in the subfield SF2, and the subfield SF.
3, SF4, SF5, SF6, SF7, SF8, SF9
Then, 64, 32, 16, 8, 4, 2, and 2 sustain discharge pulses are applied, and the PDP 1 emits light.

Next, the operation of the display device will be described with reference to FIGS. When the analog video signal a is input to the display device, the A / D converter 2 converts the analog video signal a into 9-bit digital video data.
The γ inverse correction unit 4 performs γ inverse correction on the video data and stores it in the frame memory 5 in order to maintain compatibility with the light emission characteristics of the CRT. The switching gradation determination unit 8 detects the brightness distribution of one screen of the PDP 1 based on the value of the display data that has been subjected to the γ reverse correction by the γ reverse correction unit 4, and the range of the brightness values in the detected brightness distribution is low brightness. , A range of high brightness, or a range of medium brightness, a plurality of brightness value range data set in advance (low brightness value range data,
Based on the medium brightness value range data and the high brightness value range data), each judgment output is output to the data conversion unit 6 and the subfield configuration unit 9.

In this case, the subfield construction unit 9
As described above, the vertical sync signal separated by the sync separator 7 is used as a reference, and the determination output from the switching gradation determiner 8 and the internal clock generated by the system clock generator 10 are used for each subfield. The emission time is determined according to the relative ratio of luminance, and the first subfield SF1 to the ninth subfield
The timing up to subfield SF9 is determined. That is, when the switching gradation determining unit 8 determines that the range is the low luminance range, the subfield configuring unit 9 causes the subfields SF1 to S of FIG. 2 to increase the number of gradations in the low luminance range.
Of F9, for example, lower subfields SF3 to SF9
Is assigned for data in this low luminance range, the luminance ratio of these subfields is changed, and the upper subfields SF1, SF2 are used for high luminance data so that the number of gradations is reduced for high luminance data. And change the luminance ratio of these subfields.
Then, the timing signal according to the changed luminance ratio is output to the drive unit 11.

At this time, in the data converter 6, the display data having a small value stored in the frame memory 5 (that is, the display data in the low luminance range) is assigned to the lower subfields SF3 to SF9. On the other hand, while converting the value, for the data having a large value stored in the frame memory 5 (that is, the high brightness data), the data value is converted so as to be allocated to the upper subfields SF1 and SF2, and the driving unit 11 is converted. Output. The drive unit 11 includes the display data output from the data conversion unit 6, the timing signal from the subfield configuration unit 9,
The PDP 1 is driven based on the sustaining pulse number output from the sustaining pulse number controller 12 based on the timing signal. As a result, the number of gradations increases in the low-luminance portion of the display screen of PDP1, so that when the display screen of PDP1 is entirely dark, the display image in that dark portion can be easily identified.

Further, when the switching gradation determining unit 8 determines that it is in the high luminance range, the subfield forming unit 9 increases the number of gradations in this high luminance range so that the subfields SF1 to SF9 in FIG. Of these, for example, the upper subfields SF1 to SF7 are assigned for data in the high luminance range, the luminance ratio of each of these subfields is changed, and the lower subfields are reduced so that the number of gradations is reduced for low luminance data. Fields SF8 and SF9 are allocated for these low luminance data, and the luminance ratio of the subfield is changed. Then, the timing signal according to the changed luminance ratio is output to the drive unit 11.

At this time, in the data converter 6, the display data having a large value stored in the frame memory 5 (that is, the display data in the high luminance range) is assigned to the upper subfields SF1 to SF7. While converting the value, the low-brightness data stored in the frame memory 5 is stored in the lower subfield S.
The data value is converted so as to be assigned to F8 and SF9 and output to the drive unit 11. The drive unit 11 includes the data conversion unit 6
Display data output from the subfield configuration unit 9
Similarly, the PDP 1 is driven on the basis of the timing signal from 1 and the sustaining pulse number output from the sustaining pulse number control unit 12 based on the timing signal. As a result, the number of gradations increases in the high-luminance portion of the display screen of the PDP 1, so that the gradation step becomes small in the bright portion of the display screen of the PDP 1, and smooth gradation display can be performed.

Furthermore, when the switching gradation determining unit 8 determines that the brightness is in the middle luminance range, the subfield forming unit 9
Of the subfields SF1 to SF9 of FIG. 2, for example, the middle subfields SF3 to SF7 are assigned for the data of the medium luminance range so that the number of gradations increases in the medium luminance range, and each of these subfields. Of the upper subfields SF1 and S1 for the high-luminance data and the low-luminance data, respectively, so as to reduce the number of gradations for the high-luminance data and the low-luminance data.
F2 and lower subfields SF8 and 9 are assigned, and the luminance ratio of each of these subfields is changed. Then, the driving unit 1 outputs a timing signal according to the changed luminance ratio.
Output to 1.

At this time, in the data conversion section 6, the medium luminance data (that is,
For display data in the middle luminance range), data values are converted so as to be assigned to the middle subfields SF3 to SF7, while for high luminance data stored in the frame memory 5, upper subfields SF1, SF2
The data value is converted so as to be allocated to the sub-fields, and the low-luminance data stored in the frame memory 5 is converted into the data value so as to be allocated to the lower subfields SF8 and SF9 and output to the drive unit 11. Drive unit 11
Is based on the display data output from the data conversion unit 6, the timing signal from the subfield configuration unit 9, and the sustaining pulse number output from the sustaining pulse number control unit 12 based on the timing signal. Drive PDP1. As a result, the number of gradations increases in the middle-brightness portion of the display screen of the PDP 1, so that when the screen of the PDP 1 is generally displayed with a brightness between the light and dark, the display image on that display portion can be easily identified. .

FIG. 3 is a graph showing gradation characteristics of this display device. In FIG. 3, the A / D conversion unit 2 performs A / D
An example is shown in which these display data are converted into necessary data based on the brightness distribution of the display data that has been converted and subjected to γ inverse correction by the γ inverse correction unit 4. The brightness of the input display image is converted into the low brightness portion A. In the case where the input display image is concentrated, the brightness of the input display image is concentrated in the middle brightness part C, and the brightness of the input display image is concentrated in the high brightness part B.
Each shows a situation in which the display gradation is finely set in the concentrated portion of each display data.

The operation of the main part of the present invention will be described in more detail with reference to FIG. The input display data existing in the low brightness portion A in FIG. 3 is an example in which the display gradation characteristics are biased toward the black level (dark portion) side. In this example, one screen of the PDP 1 is a dark screen as a whole such as a dark scene, and it is a screen in which it is not possible to express the gradation of the low-luminance portion and it is difficult to know what is displayed. In this case, in the present embodiment, each input display data in the low-luminance portion A is linearly increased at equal intervals like the distribution of each data indicated by the black squares in the low-luminance portion A. To arrange. That is, as described above, the switching gradation determination unit 8 detects the brightness distribution of such input display data, causes the subfield configuration unit 9 to assign the subfield and change the brightness ratio, and causes the data conversion unit 6 to do so. By converting the input display data value, the luminance interval of the input display data is narrowed in the low luminance portion B and widened in the high luminance portion. as a result,
The number of gradations in the low-luminance portion A increases, and the gradation expression in the dark portion improves. Further, in such a case, since the number of gradations in the high brightness portion is not required so much, the image quality in the high brightness portion is not deteriorated. In particular, on a screen in which only a part of the dark part is bright, it is possible to sufficiently express the gradation of the dark part and to display the bright part.

The input display data existing in the high-brightness portion B in FIG. 3 is an example in which the display gradation characteristics are biased toward the white level (bright part) side. In this example, one screen of the PDP 1 is a bright screen as a whole such as a scene of the sky, the gradation of the high-luminance portion cannot be expressed, and the gradation boundary line (gradation step) is false. It is a screen displayed as a contour.
In this case, in the present embodiment, each input display data in the high brightness portion B is linearly increased at equal intervals like the distribution of each data indicated by black circles in the high brightness portion B. Arrange. That is, the switching gradation determination unit 8 detects the brightness distribution of each input display data, causes the subfield configuration unit 9 to assign subfields and change the brightness ratio, and causes the data conversion unit 6 to input the input display data. By performing the value conversion, the luminance interval of the input display data is narrowed in the high luminance portion B and widened in the low luminance portion.
As a result, the number of gradations in the high-brightness portion B is increased and the gradation expression in the bright portion is improved. That is, in the bright portion of the display screen of the PDP 1, the gradation step becomes small and the gradation boundary line disappears, so that smooth gradation display can be performed.
Further, in such a case, since the number of gradations in the low brightness portion is not required so much, the image quality in the low brightness portion is not deteriorated. In particular, on a screen in which only a dark portion exists in the bright portion, it is possible to perform a sufficient gradation expression of the bright portion and also enable display in which the dark portion can be emphasized.

The input display data existing in the middle luminance portion C in FIG. 3 is an example in which the display gradation characteristics are concentrated in the middle of the black level (dark portion) and the white level (bright portion). In this example, one screen of PDP 1 has no bright and dark polarities. Therefore, in the present embodiment, each input display data in the middle brightness portion C is converted into the middle brightness portion C.
Arrays are arranged so as to increase linearly at equal intervals as in the data distribution indicated by black triangles. That is, the switching gradation determination unit 8 similarly detects such a brightness distribution, causes the subfield configuration unit 9 to perform subfield allocation and change of the brightness ratio, and causes the data conversion unit 6 to convert the input display data value. By performing the above, the luminance interval of the input display data is narrowed in the middle luminance portion C, and widened near the black level (low luminance portion) or near the white level (high luminance portion). As a result, the number of gradations in the medium-brightness area, which is the characteristic range of the image, increases, and the gradation expression in that area improves, and in the dark areas, it approaches the black level and in the bright areas, it approximates the white level. Therefore, it is possible to display with sharpness.

As described above, the present display device uses the statistical properties of the video signal to adaptively convert the display gradation with respect to the input signal level, thereby emphasizing the characteristic portion of the display image. It becomes possible to display. In the present embodiment, the switching gradation determination unit 8 detects the distribution of the display data in which the video data from the A / D conversion unit 2 is γ-inversely corrected by the γ-inverse correction unit 4, and the sub-field configuration unit 9 is detected. Although the luminance ratio of the subfield is changed and the data conversion section 6 is caused to convert this display data, the γ inverse correction section 4 is omitted and the distribution of the video data from the A / D conversion section 2 is changed. The switching gradation determination unit 8 detects and causes the subfield configuration unit 9 to change the luminance ratio of the subfield, and the data conversion unit 6
The same effect can be obtained by causing the conversion of this video data. Further, in the present embodiment, one field is divided into nine subfields SF1 to SF9 as shown in FIG. 2, but the same effect can be obtained by dividing into eight subfields SF1 to SF8. .

[0030]

As described above, according to the present invention, a display panel including a plurality of pixels and a timing signal for dividing a display period of one field of the display panel into a plurality of subfields having different luminance ratios are generated. A sub-field configuration section, an A / D conversion section for A / D converting an input analog video signal into video data having a bit number corresponding to the number of sub-fields, and outputting the video data to the display panel according to the timing signal. In a display device including a drive unit that performs gradation display of the display panel, the brightness distribution of one screen of the display panel is detected based on the value of the video data, and a plurality of preset brightness value range data are stored. A determination unit that determines a brightness range representing a range of brightness values in the brightness distribution based on the value of the video data in the detected brightness distribution, A data conversion unit that converts image data and outputs it to the drive unit is provided, and when the brightness range determined by the determination unit is input, the data conversion unit and the subfield configuration unit are controlled, and gradation is input within the input brightness range. Since the number is increased, the number of gradations of the low-luminance portion can be increased when the determination unit determines, for example, the low-luminance range, and thus the low-luminance portion of the screen can be accurately displayed in gradation. As a result, even if the screen of the display panel is entirely dark and it is impossible to identify what kind of image is displayed therein, the display image can be easily identified.
In addition, for example, when the determination unit determines that the range is high brightness, the number of gradations in the high brightness portion can be increased. As a result, it is possible to reduce a gradation step in a bright portion of the screen of the display panel, and as a result, it is possible to perform smooth gradation display.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a display device according to the present invention.

FIG. 2 is a diagram showing a configuration of subfields applied to a display device.

FIG. 3 is a graph showing a gradation characteristic of a PDP based on a processing result of a display device.

FIG. 4 is a diagram showing a configuration of a subfield used in a conventional display device.

FIG. 5 is a graph showing gradation characteristics of a PDP according to a conventional display device.

[Explanation of symbols]

1 ... Plasma display panel (PDP), 2 ... A /
D conversion unit, 3 ... Input data processing unit, 4 ... γ inverse correction unit, 5
... Frame memory, 6 ... Data conversion unit, 7 ... Sync separation unit, 8 ... Switching gradation determination unit, 9 ... Subfield configuration unit,
10 ... System clock generating unit, 11 ... Driving unit, 12 ...
Sustained pulse number control unit.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme coat (reference) H04N 5/66 G09G 3/28 K F term (reference) 5C058 AA11 BA07 BA13 BB03 BB04 BB13 5C080 AA05 BB05 DD02 DD05 EE17 EE29 FF12 GG08 HH01 HH02 JJ02 JJ04 JJ05 KK43

Claims (11)

[Claims] 1. A display panel comprising a plurality of pixels, a subfield configuration section for generating a timing signal for dividing a display period of one field of the display panel into a plurality of subfields having different luminance ratios, and an input analog An A / D converter for A / D converting the video signal into video data having a bit number corresponding to the number of the subfields; and a gradation of the display panel for outputting the video data to the display panel according to the timing signal. In a display device including a drive unit that performs display, a luminance distribution of one screen of the display panel is detected based on the value of the video data, and a plurality of preset luminance value range data and the detected luminance value range data are detected. A determination unit that determines a brightness range that represents a range of brightness values in the brightness distribution based on a value of video data in the brightness distribution; When the data conversion unit that converts the data and outputs the data to the driving unit and the brightness range determined by the determination unit are input, the data conversion unit and the subfield configuration unit are controlled to increase the number of gradations in this brightness range. A display device comprising: means for increasing the number of gradations. 2. The gradation number increasing means according to claim 1, when the judgment unit judges that the luminance range is in a low luminance range, the gradation of a portion corresponding to the low luminance range is determined. A display device characterized by increasing the number and reducing the number of gradations in a high-luminance portion. 3. The gradation number increasing means according to claim 1, wherein, when the determination unit determines that the brightness range is in a high brightness range, the gradation level of the part corresponding to the high brightness range is increased. A display device characterized by increasing the number and reducing the number of gradations in a low-luminance portion. 4. The gradation number increasing means according to claim 1, wherein when the determination unit determines that the brightness range is in the middle brightness range, the gradation level of the part corresponding to the middle brightness range is increased. A display device characterized by increasing the number and reducing the number of gradations of a high-luminance portion and a low-luminance portion. 5. The γ inverse correction unit according to claim 1, comprising γ inverse correction of the video data of the A / D conversion unit and outputting the image data to the data conversion unit as display data.
The said determination part detects the brightness distribution of 1 screen of the said display panel based on the value of the said display data, The display apparatus characterized by the above-mentioned. 6. The display device according to claim 1, wherein the subfield configuration unit adds a subfield having a luminance ratio of 1/2 of the minimum luminance ratio to the plurality of subfields. 7. An A / D for A / D converting an analog video signal.
1 of the display panel based on the value of the video data from the D converter
While detecting the brightness distribution of the screen, the brightness range representing the range of brightness values in the brightness distribution is determined based on a plurality of preset brightness value range data and the value of the video data in the detected brightness distribution. When the first step and the brightness range determined based on the processing of the first step are input, the brightness ratios of the data conversion unit for converting the video data and the display period of one field of the display panel are different from each other. Controls a subfield configuration unit that generates a timing signal to be divided into a plurality of subfields,
A second step of performing gradation display on the display panel by increasing the number of gradations in the input luminance range. 8. The process according to claim 7, wherein the process in the second step is based on the process in the first step, if it is determined that the brightness range is in the low brightness range, A gradation display method comprising a third step of increasing the number of gradations of a corresponding portion and reducing the number of gradations of a high-luminance portion. 9. The high-brightness range according to claim 7, wherein the process in the second step is performed when the brightness range is determined to be in a high-brightness range based on the process in the first step. A gradation display method comprising a fourth step of increasing the number of gradations of a corresponding portion and reducing the number of gradations of a low-luminance portion. 10. The process in the second step according to claim 7, wherein if it is determined that the brightness range is in the middle brightness range based on the process in the first step, A gradation display method comprising: a fifth step of increasing the number of gradations of a corresponding portion and reducing the number of gradations of a high-luminance portion and a low-luminance portion. 11. The method according to claim 7, further comprising a sixth step of γ inversely correcting the video data of the A / D conversion unit and outputting the video data as display data to the data conversion unit. A gradation display method comprising a seventh step of detecting a luminance distribution of one screen of the display panel based on the value of the display data.