JP2001255846A - Gray scale display processing device for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure display brightness of a PDP by controlling increase in address drivers of the PDP even when sub-fields are increased in the number to reduce moving pseudo images. SOLUTION: The sub-fields SF1-SF8 are divided into a 1st sub-field group (SF7, SF8) and a 2nd sub-field group (SF1-SF6); further the 1st sub-field group is divided into sub-fields D1-D4 of 64 gradations each; when an odd-numbered horizontal line 2n-1 of the PDT is selected, an even-numbered horizontal line 2n is synchronously selected; the 1st and 2nd sub-field groups are allocated to the odd-numbered horizontal line 2n-1 and also the 2nd sub-field group and the sub-fields D1, D3 are allocated to the even-numbered horizontal line; and as for the sub-fields D2, D4, they are allocated to the even-numbered horizontal line 2n when an odd-numbered horizontal line 2n+1 is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradation display processing apparatus for a plasma display panel used for displaying an image on a television or an advertisement display board.

[0002]

2. Description of the Related Art In a color plasma display panel (hereinafter, referred to as PDP), when performing gradation display, FIG.
A method of modulating the number of pulses in a field as shown in FIG. The modulation of the number of pulses in the field is 1/6
A plurality of subfields SF1, SF2, SF3, SF4, and SF in which light emission luminance is weighted within one field period (predetermined light emission period) of 0 sec (16.6 msec)
5, SF6, SF7, and SF8 are provided, and each of the subfields SF1 to SF8 has a writing period (scanning period) for writing discharge of display data and a sustain period (sustaining discharge period) for display discharge. And the light emission time (sustain period) is the number of gradations 1, 2, 4, 8, 16,
Weighted as 32, 64, 128,
Of the subfields SF1 to SF8, each subfield having the number of gradations according to the level of the input video signal is selected, and a display of 256 gradations is realized by a combination of the selected subfields.

Here, when a still image is displayed, a sufficient gradation display can be obtained by this pulse number modulation method in a field. However, when displaying a moving image, the gradation and the display color are disturbed in a portion where the gradation changes smoothly, such as a cheek of a person. Such gradation disturbance is similar to a false contour or quantization noise, and is therefore called a moving image false contour.

[0004] Various methods have been proposed to reduce such false contours of moving images. As one example, FIG.
There is a modified binary coded light emitting method as shown in FIG. Eight subfields SF1 to SF8 as shown in FIG.
In the eight subfield method using the subfield SF7 or SF having 64 or 128 gradations,
8 is large (that is, the number of gradations is large)
Lighting (light emission) / non-lighting (non-lighting)
In this case, the temporal variation of the center of gravity of light emission occurring at the time is large, so that the gradation is easily disturbed.

For this reason, as shown in FIG. 4B, the number of gradations (gradation level) 48 is changed by combining the gradation numbers 64 and 128 of the subfields SF7 and SF8 corresponding to the upper 2 bits. Having four subfields D1 to D4
Divided into In FIG. 4 (b), A is the same as FIG.
Of the subfields SF1 to SF6 of FIG.

By doing so, it is possible to reduce the disturbance of the gradation that occurs when the subfield having a large number of gradations is turned on and off. The example of FIG. 4 is an example, and various distributions of gradation levels have been proposed. However, in recent years, PDP gradation display is often performed by a 12 subfield method using 12 subfields. Was.

[0007]

In a PDP, it is necessary to perform addressing for selecting a pixel to be displayed for each subfield. In this case, about 3 .mu.sec is required for one horizontal line. You. Here, for example, in the case of a PDP having 640 × 480 pixels, P
The number of data lines (that is, the number of vertical lines) connected to each data electrode of the DP is 640, and the number of the horizontal lines (that is, scan lines and sustain lines) that are connected to each scan electrode and sustain electrode of the PDP. Is 480, but the time required for addressing when such a PDP screen is displayed as one frame is 480 (the number of horizontal lines) × 8 × 3 = 11.52 msec in the 8-subfield method.

On the other hand, in the 10 subfield system shown in FIG. 4B, 480 (the number of horizontal lines) × 10 × 3 = 14.40 ms
c and the time of one frame defined by the PDP 1
In FIG. 4, 85% of 6.6 msec (1/60 sec) is used.
The addressing time indicated by the writing period of (a) occupies. Therefore, the light emission time of the 10 subfield method (that is, equivalent to the sustain period shown in FIG. 4A) is about half of the light emission time of the 8 subfield method. This is halved with respect to the field method luminance. In consideration of such circumstances, the display screen of the PDP is displayed on horizontal lines 1 to 24.
Display block corresponding to 0 and horizontal lines 241 to 480
, And the horizontal lines of each divided display block are selected at the same time, so that the time required for addressing is reduced by half (14.
40/2 = 7.20 msec).
It is considered to realize the gradation display by the 10 sub-field method of (b). However, in this case, there is a problem that the number of address drivers for selecting the horizontal line is doubled and the cost of the device is increased. Was.

Therefore, the present invention provides a PDP even when the number of subfields is increased in order to reduce false contours of moving images.
It is an object of the present invention to secure the display brightness of a PDP without increasing the cost.

[0010]

According to the present invention, there is provided a PDP having a plurality of scan electrodes, sustain electrodes, and data electrodes, and one field period indicating a predetermined light emission period of the PDP. Is divided into a plurality of subfields (SF1 to SF8) each having a write discharge period and a sustain discharge period, and the sustain discharge period is individually weighted as the number of gradations. A conversion unit for converting the digital video signal into a digital video signal having a number of gradations corresponding to the level of the input video signal, and each electrode of the PDP according to a subfield selected according to the number of gradations of the digital video signal converted by the conversion unit A PDP having a driving unit for driving and performing a write discharge and a sustain discharge, and performing a gradation display of the PDP based on the write discharge and the sustain discharge of the drive unit
, The plurality of subfields are divided into a first subfield group (SF) according to the number of gradations.
7, SF8) and the second subfield group (SF1 to S
F6), and the first subfield group having a large number of gradations is divided into a third subfield group (D) obtained by dividing the total number of gradations of the first subfield group.
1, D3) and fourth subfield group (D2, D4)
When an odd-numbered horizontal line is selected from a plurality of horizontal lines for driving the scan electrodes and the sustain electrodes of the PDP, the driving unit selects third and fourth even-numbered horizontal lines adjacent to the odd-numbered horizontal line. Selecting means for simultaneously selecting one of the subfield groups, and allocating one of the second, third and fourth subfield groups to the selected odd horizontal line, and selecting the even number selected simultaneously with the odd horizontal line. There is provided allocating means for allocating a second subfield group to a horizontal line and third and fourth subfield groups selected simultaneously with an odd horizontal line.

The allocating means allocates the other of the third and fourth subfield groups to the even-numbered horizontal line when an unselected odd-numbered horizontal line adjacent to the even-numbered horizontal line selected by the selecting means is selected. It is. The second subfield group and the third and fourth subfield groups are assigned to the selected odd horizontal line, and the even horizontal line selected at the same time as the odd horizontal line, One of the third and fourth subfield groups assigned to the selected odd horizontal line and the third and fourth subfield groups assigned to the unselected odd horizontal line adjacent to the even horizontal line Allocating means for allocating the other, detecting the number of gradations of one and the other of the third and fourth subfield groups of each odd-numbered horizontal line, performing a predetermined calculation based on the detection result, and calculating the calculation result. Computing means for setting the number of tones of the second subfield group of the even horizontal lines.

[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 a configuration of a PDP device to which the present invention is applied. PDP that constitutes this device
The unit 100 includes M rows of data electrodes DT1 to DTM.
And scan electrodes SC1 to SC paired with each other in each of N rows
PDP 101 in which N / sustain electrodes SU1 to SUN are formed in a matrix, data driver 102 for driving the M columns of data electrodes DT via each data line, and N rows for each scan line and sustain line via each scan line and sustain line Scan electrode S
C / scanning / sustaining driver 103 for driving sustain electrode SU
Consists of

The PDP device includes a PDP unit 1
00 as a driving unit for driving the A / 00
D conversion unit 12, frame memory 13, output processing unit 14,
A synchronization separation unit 15, a timing pulse generation unit 16, a memory control unit 17, a drive timing generation unit 18, and a gradation calculation unit 19 are provided.

Next, referring to FIG.
Will be described. The magnitude of the input signal a indicating the input video signal is adjusted by the level adjustment unit 11 and output to the 8-bit A / D conversion unit 12. The A / D converter 12 converts the level of the input signal a adjusted by the level adjuster 11 into 8-bit digital data and outputs it to the frame memory 13 side. This video data is temporarily stored in the frame memory 13 and output to the data driver 102 in the PDP unit 100 by the output processing unit 14. As a result, the data driver 102 is driven, and data is output from the data driver 102 to the data electrodes DT1 to DTM of the PDP 101 via each data line DTL.

On the other hand, the synchronization separation section 15 drives the timing pulse generation section 16 based on the input signal a, and causes the timing pulse generation section 16 to generate a timing pulse.
The A / D converter 12 is controlled by the timing pulse, the input analog video signal is converted into digital data by the A / D converter 12, and the memory controller 17 is controlled by the timing pulse to control the memory. The digital data is stored in the frame memory 13 by the unit 17 and the data in the frame memory 13 is output to the output processing unit 14 by the memory control unit 17. Further, the drive timing generator 18 is controlled by the timing pulse output of the timing pulse generator 16,
PDP unit 100 by drive timing generator 18
Of the scanning / maintenance driver 103 is driven.

When the scan / sustain driver 103 of the PDP unit 100 is driven, the scan electrodes SC1 to SC of the PDP 101 are transmitted via the scan line SCL and the sustain line SUL.
The scan pulse and the sustain pulse are output to the CN and the sustain electrodes SU1 to SUN, respectively, and the video data output to the data electrodes DT1 to DTM of the PDP 101 are displayed. The output of the drive timing generator 18 is fed back to the memory controller 17. That is, the memory control unit 17
Operates in synchronization with the respective outputs of the timing pulse generator 16 and the drive timing generator 18, and the frame memory 1
3 to control the writing of the digital video data to the PDP 3 and the reading of the video data from the frame memory 13.
The image data is sent to the data driver 102 in the unit 100, the image data is output to the data electrodes DT1 to DTM, and the scanning / sustaining driver in the PDP unit 100 is output by the timing output of the drive timing generator 18 as described above. 103 is driven and video data is displayed on the PDP 101.

When displaying such a video signal, the number of gradations (light emission time) within one frame period shown in FIG. 4A is usually 1, 2, 4, 8, 16, 32, 64,
8 subfields SF weighted as 128
The gradation display by 1 to SF8 is performed. That is, the level of the input video signal a is converted into 8-bit digital data (the number of gradations) by the A / D converter 12, and a subfield corresponding to the number of gradations is, for example, the subfield S.
When F1 to SF8 are selected, gradation display is performed sequentially from the subfield SF1 having a small number of gradations. in this case,
First, after outputting video data to each data electrode DT, a scan line SCL (horizontal line) is sequentially selected to perform a write discharge, and when the write period ends, a sustain line SUL is sequentially generated.
(Horizontal line) to perform sustain discharge for a time corresponding to the number of gradations (sustain discharge period). Subfield SF1
Is completed, the gradation display by the subfield SF2 having the next smaller number of gradations is performed in the same manner. Thus, all the subfields SF1 to SF1 within one frame period
A gradation display by SF8 is performed.

FIG. 2 shows an example of a gradation display by the 10 subfield method having 10 subfields. The 10-subfield method shown in FIG. 2 is called a modified binary coded light-emitting method, in which the number of gradations is weighted as 1, 2, 4, 8, 16, 32, 64, and 128, respectively. Each subfield SF1, SF2, SF3, SF4, SF of the eight subfield system
5, SF6, SF7, SF8, large number of gradations 6
Each of the subfields SF7 and SF8 having 4,128 is divided into four subfields D1, D2, D3, and D4 each having an equal number of gradations 48 to form a first subfield group, and the remaining six subfields are divided into four subfields. Subfield SF1, SF
2, SF3, SF4, SF5 and SF6 are referred to as subfield A (second subfield group).

Here, when the number of pixels of the PDP 101 shown in FIG. 1 is, for example, 640 × 480, the number of data lines DTL (ie, the number of vertical lines) connected to each of the data electrodes DT1 to DTM of the PDP 101 is 640. And scan lines S connected to scan electrodes SC1 to SCN and sustain lines SU1 to SUN of PDP 101, respectively.
The number of CLs and sustain lines SUL is 480 each. In the present embodiment, for the sake of explanation, a pair of scanning line SCL and sustain line SUL are one horizontal line. Therefore, in such a case, the number of horizontal lines is 480.
Becomes In the case where such a PDP 101 is displayed in gradation by the modified binary coded light emitting method of FIG.
When an odd number of horizontal lines is selected by the drive unit (the output processing unit 14 and the drive timing generation unit 18) that drives the P unit 100 controlling the scan / sustain driver 103 in the unit 100, the drive unit operates in conjunction with the selection. In such a manner that the adjacent even-numbered horizontal line is selected so as to perform gradation display.

That is, each of the 480 horizontal lines SCL
When 1 to SCLN are divided into odd-numbered horizontal lines and even-numbered horizontal lines, for example, in FIG.
When 1 is selected, D1 and D3 of the even-numbered horizontal line 2n are simultaneously selected, and when odd-numbered horizontal line 2n + 1 is selected, D2 and D4 of the even-numbered horizontal line 2n and D1 and D3 of 2n + 2 of the even-numbered horizontal line are simultaneously selected. It is configured so that: In this case, odd horizontal lines 2n-1 and 2n + 1
At the time of selection, the subfields A (that is, subfields SF1 to SF6) and the subfields D1 to D in FIG.
The address is controlled so that the gradation display by No. 4 is performed. In addition, in the even-numbered horizontal line 2n, address control is performed so that gradation display is performed by the sub-field A and the sub-fields D1, D2, D3, and D4 selected by the odd-numbered horizontal line at the time of selection. Even number horizontal line 2n
When the odd-numbered horizontal line 2n-1 is selected for the sub-fields D1 and D3 of FIG.
With respect to the n sub-fields D2 and D4, address control is performed so that gradation display is performed when the odd horizontal line 2n + 1 is selected.

That is, with respect to the subfields D1 and D3, when the odd horizontal lines 2n-1 and 2n + 1 are selected, the odd horizontal lines 2n-1 and 2n + 1 and the even horizontal lines 2n and 2n + 2 selected in conjunction therewith are selected. And so on, while the sub-fields D2 and D4 are odd-numbered horizontal lines 2n-
When 1 and 2n + 1 are respectively selected, the odd horizontal lines and the even horizontal lines 2n-2 and 2n selected in conjunction with each of the odd horizontal lines are assigned so that gradation display is performed. By such address control, it is possible to obtain the same brightness as the display brightness of the conventional 8-subfield system.

Here, the number of horizontal lines is x, the number of subfields is y, and the addressing time of a horizontal line is 3 μs.
Assuming that ec, sub-field A, that is, six sub-fields SF1 to SF6 are commonly assigned to all horizontal lines. Therefore, the time t1 required for addressing is t1 = x × y × 3 μsec = 480 × 6 × 3 μsec =
8.64 msec, and the four subfields D1 to D4 are:
Since the two horizontal lines are commonly assigned, the time t2 required for addressing is t2 = (480/2) × 4 × 3 μsec = 2.88 ms
ec, and therefore, the addressing time (ie, the total writing period of each subfield) t of the horizontal line according to the present embodiment is t = t1 + t2 = 8.64 + 2.88 = 11.52 ms
ec.

As a result, when gradation display is performed by the modified binary coded light emission method of FIG. 2, since the same addressing time as that of the conventional 8-subfield method is used, the light emission time (sustain period ) Can secure a light emission time equivalent to that of the 8-subfield method. Therefore, P
Luminance equivalent to the luminance of the eight subfield system can be secured without increasing the number of scanning / sustaining drivers 103 of the DP unit 100.

When two consecutive horizontal lines are simultaneously selected and each subfield is assigned to two horizontal lines, the odd horizontal lines 2n-1 and 2n + 1 are subfield A and subfield D1 as described above. .. D4 are assigned to perform 256 gradation display from gradation number 1 to gradation number 256. When subfields are assigned to even-numbered horizontal lines 2n, the following control is performed. That is, since the number of gradations in the subfields D1 to D4 of the even-numbered horizontal line 2n is the sum of the number of gradations of the subfields D1 to D4 of the adjacent odd-numbered horizontal lines 2n-1 and 2n + 1, the gradation calculation shown in FIG. The unit 19 calculates and determines the number of tones of the subfield A of the even-numbered horizontal line 2n as follows, thereby securing the same luminance as the luminance of the conventional 8-subfield system.

That is, the number of tones of the subfields D1 to D4 of the even-numbered horizontal line 2n is set to D, and the total number of tones of the subfields D1 to D4 of the adjacent odd-numbered horizontal lines 2n-1 and 2n + 1 is set to D. Assuming that the number of gradations including the number of gradations of the subfield A set in the line 2n is G, the following expression is obtained: A ′ = GD (1) The number of gradations of the subfield A is determined.

Here, in the equation (1), when A '<0 (that is, when G <D), the number of gradations of the subfield A is set to zero. That is, in this case, the tone calculation unit 19 in FIG.
No subfield A is assigned to the even horizontal line 2n. Therefore, in the even-numbered horizontal line 2n, gradation display is performed with each gradation number of the subfields D1 to D4. Further, in the equation (1), when A ′> Amax (that is, when the value of GD is equal to or greater than the maximum number of gradations of subfield A of 64 or more), the gradation calculation unit 19 sets the sub-field for the even-numbered horizontal line 2n. The number of gradations in the field A is determined so as to be the maximum number of gradations 64.

With the above configuration, even if the number of subfields is increased for the purpose of reducing false contours of moving images, two consecutive horizontal lines can be addressed simultaneously. Need not be divided into two display blocks for addressing. Therefore, the same level of luminance as that of the conventional 8-subfield system is secured without increasing the number of scanning / sustaining drivers 103 for addressing horizontal lines. be able to.

[0028]

As described above, according to the present invention, the plurality of subfields SF1 to SF8 are divided into the first subfield group (SF7, SF8) and the second subfield group according to the number of gradations. (SF1 to SF6), and a first subfield group having a large number of gradations is divided into a total number of gradations of the first subfield group.
And a fourth subfield group (D2, D4), and an odd horizontal line is selected from a plurality of horizontal lines for driving each scan electrode and sustain electrode of the PDP. And the even horizontal lines adjacent to the odd horizontal lines are simultaneously selected and the first and second subfield groups are assigned to the selected odd horizontal lines, while the even horizontal lines selected at the same time as the odd horizontal lines are assigned to the odd horizontal lines. On the other hand, since the second subfield group and one of the third and fourth subfield groups are assigned, even if the number of subfields is increased in order to reduce the false contour of the moving image, two horizontal lines are simultaneously displayed. Since the gradation display can be selectively performed, the number of address drivers for selecting the horizontal line can be reduced, and thus the cost of the device can be reduced. It can be ensured display luminance of the device without causing up.

The second subfield group and the third and fourth subfield groups are assigned to the selected odd horizontal line, and the even horizontal line selected simultaneously with the odd horizontal line is One of the third and fourth subfield groups assigned to the selected odd horizontal line and the third and fourth subfield groups assigned to the non-selected odd horizontal line adjacent to the even horizontal line , And one of the third and fourth subfield groups of each odd-numbered horizontal line is detected, and each gradation number of the other is detected. Since the number of gradations of the subfield group of 2 is set, the display brightness of the device can be ensured without increasing the cost of the device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a gradation display processing device for a plasma display panel according to the present invention.

FIG. 2 is a diagram showing a configuration of a subfield applied to the device.

FIG. 3 is a diagram showing an example of gray scale display of the above device.

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

[Explanation of symbols]

11: Level adjustment unit, 12: A / D conversion unit, 13: Frame memory, 14: Output processing unit, 15: Synchronization separation unit, 1
6 timing pulse generator 17 memory controller 1
8: drive timing generator, 19: gradation calculator, 100
... PDP unit, 101 plasma display panel (PDP), 102 data driver, 103 scanning / sustaining driver, DT1 to DTM data electrode, DTL
... data lines, SC1 to SCN ... scan electrodes, SCL ...
Scanning line (horizontal line), SU1 to SUN: sustain electrode, SUL: sustain line, 102: data driver, S
F1 to SF8, A, D1 to D4 ... subfields.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/66 101 G09G 3/28 H

Claims (3)

[Claims] 1. A plasma display panel having a plurality of scan electrodes, sustain electrodes, and data electrodes, and one field period indicating a predetermined light emission period of the plasma display panel includes a write discharge period and a sustain discharge period. And the sustain discharge period is divided into a plurality of subfields each of which is weighted as the number of gradations,
And a conversion unit that, when a video signal is input, converts the digital video signal into a digital video signal having a number of gradations corresponding to the level of the input video signal, and is selected according to the number of gradations of the digital video signal converted by the conversion unit. A driving unit that drives each electrode of the plasma display panel in accordance with a subfield to perform write discharge and sustain discharge, and performs gradation display of the plasma display panel based on the write discharge and sustain discharge of the drive unit. In the gradation display processing apparatus for a plasma display panel, the plurality of sub-fields may be firstly changed according to the number of gradations.
And the first subfield group having a large number of gradations is divided into the third and fourth subfields obtained by dividing the total number of gradations of the first subfield group. When the odd horizontal line is selected from among a plurality of horizontal lines for driving the scan electrodes and the sustain electrodes of the plasma display panel, the driving unit divides the even horizontal line adjacent to the odd horizontal line into groups. Selecting means for simultaneously selecting, and assigning first and second subfield groups to the selected odd horizontal line, and selecting a second subfield group to the even horizontal line selected simultaneously with the odd horizontal line. Allocating means for allocating one of the third and fourth subfield groups. Tone display processing apparatus. 2. The method according to claim 1, wherein the allocating means selects the third and fourth subfield groups when an unselected odd horizontal line adjacent to the even horizontal line selected by the selecting means is selected. A gradation display processing apparatus for a plasma display panel, wherein the other is assigned to the even horizontal line. 3. A plasma display panel having a plurality of scan electrodes, sustain electrodes, and data electrodes, and one field period indicating a predetermined light emitting period of the plasma display panel includes a write discharge period and a sustain discharge period. And the sustain discharge period is divided into a plurality of subfields each of which is weighted as the number of gradations,
And a conversion unit that, when a video signal is input, converts the digital video signal into a digital video signal having a number of gradations corresponding to the level of the input video signal, and is selected according to the number of gradations of the digital video signal converted by the conversion unit. A driving unit that drives each electrode of the plasma display panel in accordance with a subfield to perform write discharge and sustain discharge, and performs gradation display of the plasma display panel based on the write discharge and sustain discharge of the drive unit. In the gradation display processing apparatus for a plasma display panel, the plurality of sub-fields may be firstly changed according to the number of gradations.
And the second subfield group, and the first subfield group having a large number of gradations is divided into the third and fourth subfields obtained by dividing the total number of gradations of the first subfield group, respectively. When the odd horizontal line is selected from among a plurality of horizontal lines for driving the scan electrodes and the sustain electrodes of the plasma display panel, the driving unit divides the even horizontal line adjacent to the odd horizontal line into groups. Selecting means for selecting simultaneously, a second sub-field group and third and fourth sub-field groups are assigned to the selected odd horizontal line, and an even horizontal line selected simultaneously with the odd horizontal line. On the other hand, one of the third and fourth subfield groups assigned to the selected odd-numbered horizontal line and one adjacent to the even-numbered horizontal line Allocating means for allocating the other of the third and fourth sub-field groups allocated to the non-selected odd-numbered horizontal lines, and each floor of one and the other of the third and fourth sub-field groups of the odd-numbered horizontal lines. Calculating means for detecting a tone number, performing a predetermined calculation based on the detection result, and setting the calculation result as the number of gradations of a second subfield group of the even-numbered horizontal line. Display processing device for a plasma display panel.