JP2003076316A - Display device and gradation display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the picture quality by reducing a false outline of a moving picture at the time of assigning intensity levels of PDP. SOLUTION: Horizontal detection parts 23 and 22 are provided, and the horizontal detection part 23 detects the luminance change between first and second adjacent pixels of a first line when data values to the pixels are '011' and '100' in order from the most significant bit respectively, and the horizontal detection part 22 detects the luminance change between third and fourth adjacent pixels of a second line following the first line when data values to the pixels are '011' and '100' respectively. A switch control part 25 controls data switches 27 and 28 in accordance with detection results of the horizontal detection parts 22 and 23 to convert data of the third and fourth pixels.

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 for displaying gradation on a display panel such as a plasma display panel.

[0002]

2. Description of the Related Art A PDP display device for displaying gray scales of a plasma display panel (hereinafter referred to as PDP) in which pixels are formed in a matrix form a level adjustment for adjusting a level of an input video signal as shown in FIG. The section 11 and the A / D conversion section 12 for A / D converting the output of the level adjustment section 11 into 8-bit display data and the display data output from the A / D conversion section 13 for γ inverse correction described later. Γ inverse correction unit 13 for performing the above, a frame memory 14 for accumulating display data from γ inverse correction unit 13 for one frame, and a frame memory 14
An output processing unit 15 for outputting the display data of PDP1 to PDP1,
A sync separator 16 that separates a sync signal (vertical sync signal) from the input video signal, and timing of A / D conversion of the A / D converter 12 based on the vertical sync signal from the sync signal separator 16. Of the PDP 1 based on the timing pulse, a timing pulse generation unit 17 that generates a timing pulse that defines the timing pulse, a memory control unit 18 that inputs the timing pulse and controls reading of display data from the frame memory 14. Drive timing generator 1 that generates a timing signal that defines the display timing of each pixel
9 and 9.

When displaying a display panel using such a PDP 1 or a ferroelectric liquid crystal element, one frame display period corresponding to 1/60 second (a period for displaying one screen of the display panel: one field period) Is composed of a plurality of sub-fields having different relative ratios of the sustain emission period (proportional to the emission luminance), which is the lighting period of the pixel.

The example of FIG. 6 is an example in which one frame display period is composed of eight subfields SF1 to SF8, and 256 grayscales are displayed by eight grayscale bits. That is, the lowest grayscale bit (first bit) corresponds to the subfield SF1, and in the following order, the second grayscale bit is in the subfield SF2 and the third grayscale bit is in the subfield SF3. The 4th bit grayscale bit is in the subfield SF4, the 5th bit grayscale bit is in the subfield SF5, the 6th bit grayscale bit is in the subfield SF6, and the 7th bit grayscale bit is in the subfield. Each of them corresponds to SF7, and the highest gradation bit (8th bit) corresponds to the subfield SF8.

As described above, the subfields SF1 to SF
8, the sustain emission period is 1 (= 2 ⁰ ) and 2 (= the number of gradations (relative ratio of emission luminance: proportional to the number of sustain emission pulses)).
2 ¹ ), 4 (= 2 ² ), 8 (= 2 ³ ), 16 (= 2
⁴ ), 32 (= 2 ⁵ ), 64 (= 2 ⁶ ), 128 (= 2
⁷ ) is weighted as

Here, each of the sub-fields SF1 to SF8
Has a scanning period in addition to the sustain emission period. In the scanning period of the subfield SF1, the display data is written to each pixel of the PDP 1 corresponding to the display data of the least significant bit (first bit). When the writing of the display data on the entire screen of the PDP 1 is completed, the sustaining light emission pulse is applied to the entire screen of the PDP once, for example, in the sustaining light emission period to cause only the written pixel to emit light.

Next, in the scanning period of the subfield SF2, the display data is written to each pixel corresponding to the display data of the second bit. When the writing of the entire screen of the PDP 1 is completed, the sustaining light emission pulse is applied to the entire screen of the PDP 1 twice, for example, in the sustaining light emission period, and only the written pixel is made to emit light. Hereinafter, for the sub-fields SF3, SF4, SF5, SF6, SF7, SF8, display data is written to each pixel according to the display data of the corresponding bit during the scanning period, and when this is completed, the next sustain emission is performed. During the period, the sustain emission pulse is 4, 8, 16, 32, 64 times, respectively.
The pixel is written 128 times, and only the pixels for which writing has been performed emit light.

[0008]

In such a PDP,
When the subfields are simply arranged in the order of the light emission period and displayed, the binary value of each display data of the adjacent first and second pixels is, for example, “01111111”. There was a rise "10000
000 ", and therefore the first pixel emits light in the sub-fields SF1 to SF7 and the second pixel emits light only in the sub-field SF8, a false motion image is displayed between the first pixel and the second pixel. Image quality deterioration called a contour occurs.
Therefore, as shown in FIG. 8, 2 pixels are provided for each of the pixels P11, P12, and P13 that are adjacent to each other on a certain horizontal line.
The decimal value "01111111", "10000000",
When the display with “01111111” is performed, the binary values “10000000” and “011” are respectively set to the adjacent pixels P21, P22, and P23 on the next horizontal line.
Display by "11111" and "10000000" is performed to cancel the false contour of the moving image.

However, as shown in FIG. 8, light emission by the light emission pattern A (binary value "01111111") is applied to the odd-numbered pixels (eg P11, P13) in the odd line and the even-numbered pixels (eg P22) in the even line. At the same time, the light emission pattern B (binary value “10000000”) is emitted to the even-numbered pixels (eg P12) of the odd-numbered lines and the odd-numbered pixels (eg P21, P23) of the even-numbered lines to cancel the false contour of the moving image. Method, that is, two types of emission patterns A having different emission centers of gravity in a fixed checkerboard pattern,
In the method of setting B as the display data of each adjacent pixel to cancel the false contour of the moving image, the light emission of two types of emission patterns A and B having different emission centers of gravity causes a checkered pattern (lattice pattern) on a display panel such as a PDP. There was a problem that the light and darkness of) occurred.

Therefore, according to the present invention, when gradation display is performed on a display panel such as a PDP, the occurrence of the grid-like light and darkness described above is suppressed, and the deterioration of image quality called moving image false contour is improved to improve the image quality. The purpose is to

[0011]

In order to solve such a problem, the present invention includes a display panel in which a plurality of pixels are arranged in a matrix, and one field display period of the display panel has a light emitting period. When divided into a plurality of weighted subfields and a video signal is input, A
Display device for performing gradation display of a display panel by performing D / D conversion and γ inverse correction to obtain n-bit display data, and selecting a subfield corresponding to the value of the display data to cause the pixel to emit light. In, when inputting each display data to the first and second pixels which are at least two adjacent pixels of the first line, at least 3 bits of the input display data consecutive from the upper bit to the lower bit side are input. It is detected whether or not the data value includes bits that become “011” and “100” in order from the high-order bit in one and the other of the adjacent pixels, and display data of the same bit position in one and the other of the adjacent pixels is detected. First detecting means for detecting a luminance change between the adjacent pixels when the values become values "011" and "100", respectively, and a line next to the first line. When each display data is input to the adjacent third and fourth pixels of the second line, the data value of at least 3 bits consecutive from the upper bit to the lower bit side of the input display data is one of the adjacent pixels. And, on the other hand, in order from the upper bit, “011” and “10”
It is detected whether or not a bit that becomes "0" is included, and when the values of the display data at the same bit position in one and the other of the adjacent pixels become the values "011" and "100", respectively, the luminance change between the adjacent pixels. And a data conversion unit that converts the values of the display data of the third and fourth pixels according to the detection results of the first and second detection units.

In this case, if the second detecting means detects a brightness change when the first detecting means does not detect a brightness change, the data converting section is configured to detect one of the third and fourth pixels in the odd field. And the value of the other display data is the first value including the value “011” and the value “10”.
In the even field, the display data values of one and the other of the third and fourth pixels are converted into the second value including "0" and the second value including the value "100" and the value "011", respectively. Is converted into a first value including. In the data conversion unit, the first and second detection units detect a change in luminance, and the display data values of one and the other of the first and second pixels each include the value “011”. And the second value including the value “100”, the display data of one and the other of the third and fourth pixels are respectively the second value including the value “100” and the value “01”.
It is converted into a first value including "1".

Further, in the data converter, the change in brightness is detected by the first and second detecting means, and the values of the display data of one and the other of the first and second pixels are respectively "011". A first value that includes and a second value that includes the value "100"
And the display data values of one and the other of the third and fourth pixels are the first value including the value “011” and the second value including the value “100”, respectively, The display data of one and the other of the third and fourth pixels are respectively converted into a second value including the value "100" and a value "01".
It is converted into a first value including "1". In the data conversion unit, the first and second detection units detect a change in luminance, and the display data values of one and the other of the first and second pixels each include the value “011”. And the second value including the value “100” and the third value
When the values of the display data of one and the other of the fourth pixel and the fourth pixel are the second value including the value “100” and the first value including the value “011”, respectively, The one display data and the other display data are the second value including the value "100" and the first value including the value "011", respectively. In addition, the data conversion unit, when the brightness change is detected by the first and second detecting means, has the third and fourth polarity so that the polarity is opposite to the polarity of the brightness change detected by the first detecting means. The display data of pixels is converted.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Generally, in a display device that displays a plasma display panel (hereinafter, PDP) or a display panel using a ferroelectric liquid crystal element, one frame display period (1
(1 field period which is a display period of the screen) is divided into a plurality of sub-fields each weighted by the sustain emission period, and the input analog video signal is A / D
The converted data is converted into digital data having the number of bits corresponding to the number of subfields, and the corresponding subfield of the PDP is caused to emit light by the subfield corresponding to the converted bit data to obtain an image of a predetermined gradation.

FIG. 1 is a block diagram showing the configuration of a PDP display device to which the present invention is applied. In FIG. 1, this P
The DP display device includes a PDP 1, a level adjusting unit 11, and A
/ D conversion unit 12, γ inverse conversion unit 13, frame memory 14, output processing unit 15, synchronization separation unit 16, timing pulse generation unit 17, memory control unit 18, drive timing generation unit 19 , And a data conversion unit 20.

Here, the level adjusting section 11 adjusts the level of the input video signal. The A / D conversion unit 12 A / D converts the level of the level-adjusted video signal and outputs it as 8-bit display data. The γ inverse correction unit 13 has eight components to maintain compatibility with the emission characteristics of the CRT.
The bit data is inversely corrected by γ. When the data of a plurality of adjacent pixels that have been subjected to γ inverse correction are input, the data conversion unit 20 detects a brightness change portion based on the input data and converts the brightness change portion so that the brightness change portion is averaged. The frame memory 14 stores the 8-bit data converted by the data converter 20.
The output processing unit 15 sets each data in the frame memory 14 to P
It is output to the data electrode as display data of each pixel of DP1.

The sync separator 16 separates the sync signal from the input video signal. Timing pulse generator 1
Reference numeral 7 is for generating various timing signals such as timings at the time of data conversion by the A / D conversion unit 12 and the data conversion unit 20 based on the vertical synchronization signal extracted by the synchronization separation unit 16. The memory control unit 18 outputs the display data in the frame memory 14 to the output processing unit 15 side based on the timing signal of the timing pulse generation unit 17. The drive timing generation unit 19 uses the timing signals from the timing pulse generation unit 17 and the memory control unit 18 to determine the above-mentioned subfield timing and P
A pulse signal for driving each scan electrode and sustain electrode of DP1 is generated.

Generally, in a PDP display device of this type, as is well known, an input video signal is converted into an A / D conversion signal by an A / D converter 12.
After D / D conversion into 8-bit display data, γ inverse correction is performed to maintain compatibility with the emission characteristics of the CRT. In the present embodiment, the data conversion unit 20 detects the brightness change portion that causes the occurrence of the false contour of the moving image from each data of the adjacent pixels after the γ inverse correction, and performs the data conversion so that the brightness change is reduced. As a result, the false contour of the moving image described above is reduced.

Further, in the present embodiment, the A / D converter 1
The 8-bit data of 256 gradations A / D converted by 2 is subjected to γ-inverse correction by the γ-inverse correction unit 13A, and the γ-inverse-corrected data has the number of gradations for each light emission period as shown in FIG. 1 (= 2 ⁰ ), 2 (= 2 ¹ ), 4 (= 2
² ), 8 (= 2 ³ ), 16 (= 2 ⁴ ), 32 (= 2
⁵ ), 64 (= 2 ⁶ ), and 128 (= 2 ⁷ ), P by 8 subfields SF1 to SF8
The gradation display of each pixel in DP1 is realized.

(First Embodiment) FIG. 2 is a diagram showing a first embodiment of a PDP display device, and is a diagram for explaining the data conversion operation of the above-mentioned data conversion unit 20. Figure 2
As shown in (f), the pixels P11 and P12 are sequentially arranged in the odd line n + 1 of the PDP 1, and the odd line n +
In the even line n + 2, which is the line next to 1, the pixel P1
When the pixels P21 and P22 are sequentially arranged corresponding to 1 and P12, the binary value of each 8-bit display data of the adjacent pixels P11 and P12 is, for example, “01111111” in order from the upper bit, and 1 from this. That is, the number of gradations has increased and a carry has occurred, which is "10000000".
When the pixel P12 emits light in F7 and the pixel P12 emits light only in the subfield SF8 having the largest gradation number,
A vertical moving image false contour occurs between 11 and P12. Even when such a combination of display data exists between the pixels P21 and P22 shown in FIG. 2 (f), a moving image false contour in the vertical direction similarly occurs between these pixels. Further, such a combination of display data is the pixel P1 shown in FIG.
Even if it exists between 1 and P21 and between pixels P12 and P22, a horizontal moving image false contour occurs between these adjacent pixels.

Further, the combination of display data of adjacent pixels in which such a false contour of a moving image is generated is not limited to the above-mentioned example of 8-bit data, but "0" for lower 7-bit data.
111111 "and" 1000000 ", and" 011111 "and" 100000 "for the lower 6-bit data,
"01111" and "10" for the lower 5 bit data
000 ”,“ 0111 ”for the lower 4 bits of data
And “1000”, and for the lower 3 bits of data, there are combinations of “011” and “100”. Further, for example, the lower 5 bit data “01” shown in FIG.
For example, 110 "and" 10001 "have consecutive upper three-bit data of 8-bit data, the data of one pixel is" 011 ", and the data of the other pixel is" 100 ".
Also in the case of the combination, the moving image false contour is generated between these adjacent pixels. When the display data of such a combination is input, the data conversion unit 20 determines that the luminance change between adjacent pixels is large, and performs data conversion so that the luminance change is reduced. Thereby, the false contour of the moving image can be reduced.

FIG. 3A is a block diagram showing the structure of the data conversion unit 20. The data conversion unit 20 is shown in FIG.
As shown in (a), a line memory 21 that stores the data of each pixel on one line and a horizontal detection unit 22 that simultaneously inputs the data of two pixels that are adjacent in the horizontal direction and detects the brightness change in the horizontal direction. And a horizontal detection unit 23 that simultaneously inputs the data of the four horizontally adjacent pixels one line before stored in the line memory 21 and detects the luminance change between these data, and the two horizontal adjacent pixels. A vertical detection unit 24 for simultaneously inputting data and data of two pixels vertically adjacent to the two pixels and detecting a luminance change between these data, a switch control unit 25,
26, data switches 27 to 30, and delay units 31 to 3 for delaying data in the horizontal direction by one pixel (one dot).
4, delay units 35 to 38 that delay the data in the horizontal direction by 2 pixels (2 dots), and a delay unit 39 that delays the data in the horizontal direction by 3 pixels (3 dots).

Here, as shown in FIG. 3B, the PDP
Pixels Px1, Px2, Px in the horizontal line n + 1 of 1
3 and Px4 are arranged in this order, and pixels Py2 and Py3 are arranged in the next horizontal line n + 2 corresponding to the pixels Px2 and Px3.
Is arranged, the data of each pixel that has been γ-inversely corrected by the γ-inverse correction unit 13 is the pixel Px of the horizontal line n + 1.
1, Px2, Px3, Px4 are input in the order of input data IN to the data conversion unit 20, and then the next horizontal line n is input.
Assuming that the data of the pixels Py2 and Py3 of +2 are sequentially input to the data conversion unit 20, the data value of the pixel Py2 delayed by one pixel by the delay unit 31 in the horizontal detection unit 22 and the data of the pixel Py3 directly input. By simultaneously inputting and comparing the values with each other, it is possible to detect a luminance change between both pixels. Then, at the same time, the horizontal detector 23 simultaneously stores each pixel Px1, which is one line before (that is, line n + 1), stored in the line memory 21.
The data of Px2, Px3, and Px4 are the delay units 3 respectively.
Since it is input via 9, 38, 32 or directly,
The horizontal detection unit 23 can simultaneously input and compare the data values of the pixels on the preceding line to detect the luminance change between these pixels.

Next, the data conversion operation of the data conversion unit 20 will be described in more detail with reference to FIGS. (1) First, in the horizontal detection unit 22 to which the data of the pixels Py2 and Py3 in FIG. 3B are input, a luminance change that causes a false contour of a moving image is detected, and each pixel Px1, which is one line before the pixel change, is detected. When no change in brightness is detected in the horizontal detection unit 23 to which the data of Px2, Px3, and Px4 is input, the switch control unit 25 causes the odd-numbered feed to operate as shown in FIG.
The data switches 27 and 28 are controlled so that the data conversion shown in (b) is performed, and the data conversion shown in FIG. 2 (c) is performed in the even field. That is, the input data of the pixels Py2 and Py3 is “0” as shown in FIG.
1110 ”and“ 10001 ”, the pixel Py2
The input data of Py3 is set to "0" in each odd field.
1111 "and" 10000 "are converted to" 10000 "and" 01111 "in the even field, respectively.

The above example (1) is applied to line n in FIG. 4 (a).
When applied to the input data to each pixel of +1, n + 2,
Each pixel P1 of line n + 1 input to the horizontal detection unit 23
Since the data of 1 to P16 are all “10001”, it is detected that there is no brightness change.
Next, the data of pixels P24 and P25 of the next line n + 2 “10
When "001" and "01110" are input and a change in luminance between the horizontal adjacent pixels P24 and P25 is detected, the switch control unit 25 causes the data of the horizontal adjacent pixels P24 and P25 to be displayed in odd fields. The data switches 27 and 28 are controlled so that "10000" and "01111" shown in FIG. 4B and "01111" and "10000" shown in FIG.

(2) In addition, in the horizontal detector 22, FIG.
In the horizontal detection unit 23 in FIG. 3B in which the luminance change between the data of the pixels Py2 and Py3 is detected and the luminance change of the data one line before is detected, each pixel Px in FIG.
The brightness change between the data of 2 and Px3 is detected, and the value of the data of one line before input to the horizontal detection unit 23 is
In the case of “01111” and “10000” as shown in FIG. 2B, the switch control unit 25 causes the pixels Px2 and Px3 to be displayed.
2C regardless of whether the input data of each pixel Py2, Py3 corresponding to the vertical direction is odd or even.
The data switches 27 and 28 are controlled so as to be “10000” and “01111” shown in FIG.

The above example (2) is applied to line n in FIG. 4 (c).
When applied to the input data to each pixel of +2, n + 3,
Each pixel P2 of the line n + 2, which is input as the previous line data to the horizontal detection unit 23 after the data conversion is performed
The data of P4 and P25 are "01111" and "1", respectively.
Therefore, when the brightness change is detected and the data of the pixels P34 and P35 of the next line n + 3 is input to the horizontal detection unit 22 and the brightness change between the input data is detected, the switch control unit 25 Horizontal adjacent pixel P34,
The data of P35 are "10000" and "01", respectively.
The data switches 27 and 28 are controlled so as to be "111".

(3) In addition, in the horizontal detecting section 22, FIG.
The brightness change between the data of the pixels Py2 and Py3 in (b) is detected, and the brightness change between the data of the pixels Px2 and Px3 in FIG.
Further, when the value of the data input to each horizontal detection unit 23 is “10000” or “01111” as shown in FIG. 2C, the switch control unit 25 causes the pixel control units Py2 and Py3.
The data switches 27 and 28 are controlled so that the input data of (1) becomes "01111" and "10000" shown in FIG. 2B regardless of the odd and even fields.

The above example (3) is applied to line n in FIG. 4 (b).
When applied to the input data to each pixel of +2, n + 3,
After the data conversion is performed, each pixel P2 of the line n + 2, which is input to the horizontal detection unit 23 as the data one line before, is input.
The data of P4 and P25 are "10000" and "0", respectively.
Since it is 1111 ”, it is detected that there is a brightness change,
At this time, the horizontal detection unit 22 displays the pixel P3 of the next line n + 3.
When the data of P4 and P35 are input and a change in luminance between the input data is detected, the switch control unit 25 determines that the data of the horizontally adjacent pixels P34 and P35 is "0111".
Data switch 2 so that it becomes 1 ”and“ 10000 ”
7, 28 are controlled.

(4) In addition, in the horizontal detector 22, FIG.
The luminance change between the data of the pixels Py2 and Py3 in (b) is detected, and the horizontal detection unit 23 also detects each pixel Px2 and Py2.
The brightness change between the Px3 data is detected, and the data values input to the horizontal detection unit 22 are “10000” and “01111” as shown in FIG. When the value of the data to be stored is “01111” and “10000” as shown in FIG. 2B, the switch control unit 25 irrespective of whether the input data of the pixels Py2 and Py3 are odd and even fields. The data switches 27 and 28 are controlled so as to be “10000” and “01111” shown in FIG. 2C. That is, in this case
The input data to the pixels Py2 and Py3 are not converted and become the input data to the pixels Py2 and Py3 as they are.

The above example (4) is applied to line n in FIG. 4 (c).
When applied to the input data to each pixel of +2, n + 3,
After the data conversion is performed, each pixel P2 of the line n + 2, which is input to the horizontal detection unit 23 as the data one line before, is input.
The data of P4 and P25 are "01111" and "1", respectively.
Since it is "0000", it is detected that there is a brightness change,
At this time, the data of the pixels P34 and P35 of the next line n + 3 input to the horizontal detection unit 22 are respectively "1000".
If it is “0” or “01111”, the switch control unit 2
5 controls the data switches 27 and 28 so that the data of the horizontally adjacent pixels P34 and P35 are "10000" and "01111", respectively.

(5) Further, the horizontal detecting section 22 detects the luminance change between the data of the pixels Py2 and Py3, and the horizontal detecting section 23 also detects the luminance change between the data of the pixels Px2 and Px3. As shown in FIG. 2B, the value of the data input to the horizontal detection unit 22 is “0111”.
1 "and" 10000 ", and the value of the data input to the horizontal detection unit 23 is" 1000 "as shown in FIG.
In the case of “0” and “01111”, the switch control unit 2
5 is “011” shown in FIG. 2B regardless of whether the input data of each pixel Py2, Py3 is odd or even.
The data switches 27 and 28 are controlled so as to be "11" and "10000". That is, also in this case, each pixel Py
The input data to Py2 and Py3 are not converted and become the input data to the pixels Py2 and Py3 as they are.

The above example (5) is applied to line n in FIG. 4 (b).
When applied to the input data to each pixel of +2, n + 3,
After the data conversion is performed, each pixel P2 of the line n + 2, which is input to the horizontal detection unit 23 as the data one line before, is input.
The data of P4 and P25 are "10000" and "0", respectively.
Since it is 1111 ”, it is detected that there is a brightness change,
At this time, the data of the pixels P34 and P35 of the next line n + 3 input to the horizontal detection unit 22 are respectively "0111".
If it is “1” or “10000”, the switch control unit 2
5 controls the data switches 27 and 28 so that the data of the horizontally adjacent pixels P34 and P35 are "01111" and "10000", respectively.

(6) Further, the pixel Px4 in FIG. 3 (b), which is one line before the data converted by the switch controller 25, is used.
The data of Px3, Px2, and Px1 is, for example, as shown in FIG.
Like "01110", "10000",
The horizontal detection unit 23 sets “01111” and “10001”.
3 is detected by the switch controller 25,
The data of the pixels Py2 and Py3 on the next line in (b) is converted so as to have a polarity opposite to the polarity of the luminance change (data digit change) between the pixels one line before which the data conversion was performed by itself. That is, the data value of the high-order bit of each of the one and the other pixels of the adjacent pixels on a certain line is “011”,
When converted as carry data of gradations such as "100", gradation is such that data of one pixel is "100" and data of the other pixel is "011" in adjacent pixels on the next line. Converted as carry data. In addition, the data values of the upper bits of one and the other pixels of the adjacent pixels on a certain line are “100” and “011”, respectively.
When converted as the carry-down data of the gradation, the data of one pixel is “01
1 ", and the data of the other pixel is converted as carry data of the gradation that becomes" 100 ".

The above example (6) is applied to line n in FIG. 4 (b).
The case of applying it to the input data to each pixel of +3 and n + 4 will be described. First, as the data of the pixels P43 and P44 of the line n + 4 of FIG. 4B, the data “10001” as shown in FIG.
When "01110" is input and a change in brightness is detected, the horizontal detection unit 23 stores, as the data immediately preceding that line, the pixels P32 and P of the line n + 3 shown in FIG. 4B.
33, P34, P35 data, "10001",
"10001", "01111", and "10000" are simultaneously input. In this case, the switch control unit 25 converts the data of the pixels P43 and P44 of the line n + 4 into the data of each pixel one line before, that is, the data “01111” and “1000” of the pixels P34 and P35.
The conversion is performed so as to be "10000" and "01111" which have opposite polarities to "0".

The above example (6) is applied to line n in FIG. 4 (c).
The same applies when applied to the input data to the +3 and n + 4 pixels. That is, line n + 4 in FIG.
Of the pixels P43 and P44 of the
The data value “1000” as shown in FIG.
1 ”and“ 01110 ”are input and a change in brightness is detected, the horizontal detection unit 23 stores, as the data immediately preceding that line, each pixel P32 of line n + 3 shown in FIG.
Each data of P33, P34, P35, “10001”,
"10001", "10000", and "01111" are simultaneously input. In this case, the switch control unit 25 converts the data of the pixels P43 and P44 of the line n + 4 into the data of each pixel one line before, which is the data “10000” and “0111” of the pixels P34 and P35.
Conversion is performed so that the polarities are “01111” and “10000”, which are opposite in polarity to “1”.

The data converted in this way is shown in FIG.
Data values in the odd field of (b) and FIG.
The data values in the even field of (c) are combined to obtain a display as shown in FIG. 4 (d), and as a result, it is possible to reduce the brightness of the display in the luminance change portion where the display data value changes. As a result, it is possible to solve the conventional problem that a checkered pattern of light and dark occurs on the PDP 1 as shown in FIG.

(Second Embodiment) In the first embodiment, the horizontal detectors 22 and 23 detect a change in luminance of input data of adjacent pixels in the horizontal direction, and perform data conversion according to the detected data. In the second embodiment, an example in which the luminance change of the input data of each adjacent pixel in the vertical direction is detected and the data conversion is performed will be described with reference to FIGS. 3 and 5.

As shown in FIG. 3C, for example, the pixels Px1 and Px2 are sequentially arranged on the horizontal line n + 1, and the pixels Py1 and Py2 are arranged on the next horizontal line n + 2 corresponding to the respective pixels Px1 and Px2. If yes, then Figure 3
In the vertical detection unit 24 of (a), the data of the pixel Py1
The data of the pixel Py2 delayed by the delay unit 33, the data of the pixel Px1 one line before stored in the line memory 21, and the data of the pixel Px2 stored in the line memory 21 and delayed by the delay unit 34 are simultaneously performed. It is possible to input and detect a brightness change between these data.

Here, the pixels of the PDP 1 are arranged in 6 rows and 6 columns as shown in FIG. 5, and the value (luminance level value) of the lower 5 bits of each pixel input to the data conversion unit 20 is the horizontal line n + 1. Pixels P11 to P16, horizontal line n + 2
Pixels P21 to P26, and a pixel P51 on the horizontal line n + 5
-P56, "01111" in pixels P61-P66 of horizontal line n + 6, and continuous horizontal lines n + 3, n
In each of the +4 pixels P31 to P36 and P41 to P46, when the number of gradations is increased by one from "01111" and a carry is generated, "10000", the vertical detection unit 24.
Is between each pixel of the horizontal line n + 2 and each pixel of the horizontal line n + 3 one line after this line, and the horizontal line n.
It is possible to similarly detect the vertical luminance change that occurs between each pixel of +4 and each pixel of the horizontal line n + 5 which is one line after this line.

Based on the detection output of the vertical detection section 24, the switch control section 26 determines whether the odd field is as shown in FIG.
, Each pixel P21, P2 of the horizontal line n + 2
The data switches 29 and 30 are controlled so that the data value of P3, P25 is converted to "01111" and the data value of each pixel P22, P24, P26 of the horizontal line n + 2 is converted to "10000". Further, the data value of each pixel P41, P43, P45 of the horizontal line n + 4 is “0111.
1 ", each pixel P42, P44, P of the horizontal line n + 4
The data switches 29 and 30 are controlled so that the data value of 46 is converted into "10000".

In the even field, the switch control unit 26, as shown in FIG. 5C, has a horizontal line n + 2.
The data value of each pixel P21, P23, P25 of
00 ", each pixel P22, P24, of the horizontal line n + 2,
The data switches 29 and 30 are controlled so that the data value of P26 is converted into "01111", respectively. Also,
The data switches 29, 30 are arranged so that the data values of the pixels P41, P43, P45 of the horizontal line n + 4 are converted to "10000" and the data values of the pixels P42, P44, P46 of the horizontal line n + 4 are converted to "01111". To control.

As described above, in each pixel having the data value "01111", there are two pixels having the data value "10000" in which the number of gradations is increased by one and the carry is generated.
Even when the pixels are continuously distributed on one horizontal line (that is, when the pixels having the data value “10000” are continuously distributed in the vertical direction by two pixels), the data conversion unit 20 performs the above-described data conversion processing to determine the adjacent vertical pixels. Since the change in luminance between them is suppressed and the false contour of the moving image is visually diffused, the false contour of the moving image can be reduced. Further, by making the emission pattern of the odd field and the emission pattern of the even field opposite to each other and synthesizing these patterns, the false contour of the moving image is further diffused visually, and the false contour of the moving image can be further reduced.

In the present embodiment, as shown in FIG. 6, the light emission periods are gradation numbers 1 (= 2 ⁰ ) and 2 (= 2), respectively.
¹ ), 4 (= 2 ² ), 8 (= 2 ³ ), 16 (= 2 ⁴ ),
Eight subfields SF1 to SF weighted as 32 (= 2 ⁵ ), 64 (= 2 ⁶ ), and 128 (= 2 ⁷ ).
Although the example in which the gradation display of each pixel in the PDP 1 is performed by 8 is described, the present invention is not limited to this example, and even when the number of subfields is changed and the emission luminance ratio of each subfield is changed. The same effect can be obtained by detecting the carry or the carry of the gradation based on the display data of the adjacent pixels and setting the converted data value to the corresponding value.

[0045]

As described above, according to the present invention, a display panel in which a plurality of pixels are arranged in a matrix is provided, and one field display period of the display panel is divided into a plurality of sub-pixels each weighted by a luminance ratio. When the video signal is divided into fields, A / D conversion and γ inverse correction are performed to obtain n-bit display data, and a subfield corresponding to the value of the display data is selected to select the sub-field of the pixel. In the display device for displaying the key,
And a second change detecting means and a data converting means are provided, and the first detecting means inputs each display data to the first and second pixels which are at least two adjacent pixels of the first line, Whether or not the data value of at least 3 bits consecutive from the upper bit to the lower bit of the input display data includes bits which become "011" and "100" in order from the upper bit in one and the other of the adjacent pixels, respectively. And the value of the display data at the same bit position in one and the other of the adjacent pixels is "011".
And the brightness change between the adjacent pixels is detected when the value becomes "100", the second detecting means detects the adjacent third and fourth pixels of the second line which is the next line of the first line. When each of the display data is input, the change in brightness between the adjacent pixels is detected based on the input display data, and the data conversion unit determines the third and fourth pixels according to the detection results of the first and second detection means. Since the value of the display data is converted, the false contour of the moving image can be reduced and the image quality of the display panel can be improved when gradation display is performed on the display panel such as a PDP.

[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 an example of data conversion by a display device.

FIG. 3 is a block diagram of a data conversion unit that performs data conversion.

FIG. 4 is a diagram showing a first data conversion example by a display device.

FIG. 5 is a diagram showing a second data conversion example by the display device.

FIG. 6 is a diagram showing an arrangement configuration of subfields in a display device.

FIG. 7 is a block diagram of a conventional PDP display device.

FIG. 8 is a diagram showing a conventional data conversion example.

[Explanation of Codes] 1 ... PDP, 12 ... A / D conversion unit, 13 ... γ inverse correction unit,
14 ... Frame memory, 15 ... Output processing unit, 16 ... Sync separation unit, 17 ... Timing pulse generation unit, 18 ... Memory control unit, 19 ... Drive timing generation unit, 20 ... Data conversion unit, 21 ... Line memory, 22, 23 ... Horizontal detection unit,
24 ... Vertical detection unit, 25, 26 ... Switch control unit, 27
-30 ... Data switch, 31-39 ... Delay unit, P11
~ P16, P21 to P26, P31 to P36, P41 to
P46, P51 to P56, P61 to P66 ... Pixels.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 H04N 5/66 A H04N 5/66 G09G 3/28 K F term (reference) 5C058 AA07 AA08 AA11 BA01 BA05 BA07 BA13 BA16 BA33 BB03 BB09 BB13 BB22 BB23 5C080 AA05 BB05 DD05 DD30 EE19 EE29 FF12 JJ01 JJ02 JJ04

Claims (12)

[Claims] 1. A display panel in which a plurality of pixels are arranged in a matrix is provided, and one field display period of the display panel is divided into a plurality of subfields each having a weighted emission period, and a video signal is input. A
A / D conversion and γ inverse correction are performed to obtain n-bit display data, and a gradation is displayed on the display panel by selecting a subfield according to the value of the display data and causing the pixel to emit light. In the display device, when each display data is input to at least two adjacent pixels of the first line, that is, at least two pixels which are consecutive from the upper bit to the lower bit of the input display data. The data value of the bit is “011” in order from the upper bit in one and the other of the adjacent pixels.
It is detected whether or not a bit that becomes "100" is included, and the values of the display data at the same bit position in one and the other of the adjacent pixels are the values "011" and "10", respectively.
A first detecting means for detecting a change in luminance between the adjacent pixels when the value becomes "0", and a second line which is a line next to the first line to adjacent third and fourth pixels. When each display data is input, a data value of at least 3 bits consecutive from the upper bit to the lower bit side of the input display data becomes “011” and “100” in order from the upper bit in one and the other of the adjacent pixels, respectively. It is detected whether or not the bit is included, and the value of the display data at the same bit position in one and the other of the adjacent pixels is the value “011”.
And the display data of the third and fourth pixels according to the detection results of the first and second detecting means, the second detecting means detecting the change in luminance between the adjacent pixels when it becomes "100". A display device comprising: a data conversion unit for converting a value. 2. The odd number field according to claim 1, wherein the data conversion section detects a luminance change by the second detection means when a luminance change is not detected by the first detection means. The values of the display data of one and the other of the third and fourth pixels are converted into a first value including the value “011” and a second value including the value “100”, respectively, and in the even field, A display characterized by converting a value of display data of one and the other of the third and fourth pixels into a second value including the value "100" and a first value including the value "011", respectively. apparatus. 3. The data conversion unit according to claim 1, wherein the first and second detection units detect a change in luminance, and the display data values of one and the other of the first and second pixels are When the value is the first value including the value “011” and the second value including the value “100”, respectively, the display data of one and the other of the third and fourth pixels is set to the value “100”. A second value including "and the value" 01
A display device which is converted into a first value including "1". 4. The data conversion unit according to claim 1, wherein the first and second detection units detect a change in luminance, and the display data values of one and the other of the first and second pixels are Each of the display data is a first value including the value “011” and a second value including the value “100”, and the values of the display data of one and the other of the third and fourth pixels are the values respectively. When the first value including “011” and the second value including the value “100”, the display data of one and the other of the third and fourth pixels are respectively included in the first value including the value “100”. A display device which is converted into a first value including a value of 2 and the value “011”. 5. The data conversion unit according to claim 1, wherein the first and second detection units detect a luminance change, and the display data values of one and the other of the first and second pixels are Each of the display data is a first value including the value “011” and a second value including the value “100”, and the values of the display data of one and the other of the third and fourth pixels are the values respectively. When the second value including “100” and the first value including the value “011”, the display data of one and the other of the third and fourth pixels respectively includes the first value including the value “100”. A display device having a first value including a value of 2 and the value "011". 6. The data conversion unit according to claim 1, wherein when the brightness change is detected by the first and second detecting means, the polarity of the brightness change detected by the first detecting means is opposite to that of the brightness change. A display device, characterized in that the display data of the third and fourth pixels are converted so as to become polar. 7. A display panel in which a plurality of pixels are arranged in a matrix is provided, and one field display period of the display panel is divided into a plurality of subfields each having a weighted emission period, and a video signal is input. A
A / D conversion and γ inverse correction are performed to obtain n-bit display data, and a gradation is displayed on the display panel by selecting a subfield according to the value of the display data and causing the pixel to emit light. In the display device, when each display data is input to at least two adjacent pixels of the first line, that is, at least two pixels which are consecutive from the upper bit to the lower bit of the input display data. The data value of the bit is “011” in order from the upper bit in one and the other of the adjacent pixels.
It is detected whether or not a bit that becomes "100" is included, and the values of the display data at the same bit position in one and the other of the adjacent pixels are the values "011" and "10", respectively.
A first step of detecting a luminance change between the adjacent pixels when it becomes "0", and a second line next to the first line to adjacent third and fourth pixels. When display data is input, the data value of at least 3 bits consecutive from the upper bit to the lower bit of the input display data becomes “011” and “100” in order from the upper bit in one and the other of the adjacent pixels. Whether or not a bit is included is detected, and the value of the display data at the same bit position in one and the other of the adjacent pixels is the value “011”.
And the display data of the third and fourth pixels according to the detection result based on the processing of the first and second steps, and the second step of detecting the luminance change between the adjacent pixels. Third to convert the value of
And a gradation display method. 8. The process according to claim 7, wherein in the process in the third step, a brightness change is detected based on the process in the second step when a brightness change is not detected based on the process in the first step. If the odd field is the third and fourth
The display data values of one and the other of the pixels are converted into a first value including the value "011" and a second value including the value "100", and at the same time, in the third and fourth fields. And a fourth step of converting the values of the display data of one and the other of the pixels of the above into a second value including the value “100” and a first value including the value “011”, respectively. How to display gradation. 9. The processing in the third step according to claim 7, wherein a change in brightness is detected based on the processing in the first and second steps, and one and the other of the first and second pixels are detected. When the values of the display data are the first value including the value “011” and the second value including the value “100”, respectively, the display data of one and the other of the third and fourth pixels are displayed. A gradation display method comprising: a fifth step of converting into a second value including the value “100” and a first value including the value “011”. 10. The processing in the third step according to claim 7, wherein a change in luminance is detected based on the processing in the first and second steps, and one and the other of the first and second pixels are detected. The values of the display data are the first value including the value “011” and the second value including the value “100”, respectively, and the value of the display data of one and the other of the third and fourth pixels, respectively. Are respectively a first value including the value “011” and a second value including the value “100”, display data of one and the other of the third and fourth pixels, respectively,
A second value including the value “100” and the value “011”
A gradation display method comprising a sixth step of converting to a first value including. 11. The processing according to claim 7, wherein in the processing in the third step, a luminance change is detected based on the processing in the first and second steps, and one and the other of the first and second pixels are detected. The values of the display data are the first value including the value “011” and the second value including the value “100”, respectively, and the value of the display data of one and the other of the third and fourth pixels, respectively. Are respectively a second value including the value “100” and a first value including the value “011”, display data of one and the other of the third and fourth pixels, respectively,
A second value including the value “100” and the value “011”
A gradation display method comprising: a seventh step of setting the first value to include. 12. The process according to claim 7, wherein the process in the third step is detected based on the process of the first step when a brightness change is detected based on the process of the first and second steps. A gradation display method comprising: an eighth step of converting display data of the third and fourth pixels so that the display data has a polarity opposite to that of the brightness change.