JPH11352930A - Driving method for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide clear image display keeping the luminance constant all the time by preparing a plasma display panel(PDP) driving wave form using a signal converted into a prescribed vertical scanning frequency through scan- conversion of an input signal. SOLUTION: A scan conversion part 2 scan-converts an input signal into a specified vertical scanning frequency. A sub-field forming part 3 realizes gradation expression in a PDP. A drive part 4 drives a PDP 5 of a display device. A PDP driving part 6 is composed of the sub-field forming part 3 and the drive part 4. Image signals, for example, of a NTSC with 525 pieces of scanning lines and 60 Hz of the vertical scanning frequency, are input, and the signals are supplied to the conversion part 2 to be converted into signals corresponding to the number of PDP picture elements. A PDP driving wave form is prepared using the signals from the conversion part 2 in the PDP driving part 6 comprising the sub-field forming part 3 and the drive part 4 to provide clear image display keeping the luminance constant all the time thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a plasma display panel having a memory function, and more particularly to a method of driving a plasma display panel having a memory function, when receiving various signal sources, a luminance change due to a change in a vertical scanning frequency and a luminance unevenness due to various factors. ,
Further, the present invention relates to a method for driving a plasma display panel that significantly reduces sharpness reduction.

[0002]

2. Description of the Related Art In recent years, a plasma display panel device has been attracting attention as one of the promising candidates for a wall-mounted television because of its large panel size and wide viewing angle. ｛For example, (Takano "PDP" Television Society Journal Vol.48, No.
9 (1994) pages 1098 to 1101110.

[0003] As a conventional plasma display panel device, for example, a plasma display panel device for displaying a moving image by a method in which a DC plasma display panel (hereinafter abbreviated as PDP) is provided with a memory function is described in Owaki (P. Display "Kyoritsu Publishing Co., Ltd. (19
1983) There are pages 211 to 215｝.

However, in this method, when the vertical scanning frequency of the signal changes, the brightness changes and the white balance adjustment is very complicated.

On the other hand, as a method of adjusting the number of times of discharge light emission in accordance with the vertical scanning frequency to keep the luminance constant, a multi-scan adaptive plasma display device disclosed in Japanese Patent Application Laid-Open No. 8-76716 has been proposed. As a method of correcting and making the white balance of each PDP uniform,
Japanese Patent Application Laid-Open No. 8-336155 discloses a white balance device disclosed in public information.

[0006]

However, in the above-described conventional configuration, there is a problem that the number of times of discharge light emission is minutely changed in order to keep the luminance constant, so that the gradation is remarkably deteriorated. Further, there is another problem that uniform image display cannot be realized at a two-dimensional spatial position only by gamma correction. Furthermore, the optimal driving method of the plasma display panel has not been clarified.

In view of the foregoing, the present invention drives a plasma display panel with a conversion signal obtained by scan-converting an input video signal into a signal having a predetermined vertical scanning frequency, thereby keeping the luminance constant and converting the input video signal. By performing gamma correction after performing luminance correction at a two-dimensional spatial position, a uniform image can be displayed. Further, by performing contour compensation of two systems having different boost frequencies, the signal S
It is an object of the present invention to provide a driving method of a plasma display panel which can realize a clear image display with little / N degradation.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a converting means for scan-converting an input video signal into a signal having a predetermined vertical scanning frequency, and a plasma display panel using a signal from the converting means. And a display means for displaying an image by driving the image signal, and controlling so as to obtain a constant screen luminance even when the vertical scanning frequency of the input video signal changes.

Further, according to the present invention, there is provided a luminance correcting means for correcting the luminance of an input video signal at a two-dimensional spatial position, a gamma correcting means for performing gamma correction with a signal from the luminance correction, and a plasma using a signal from the gamma correcting means. Display means for driving the display panel to display an image, thereby displaying a uniform image.

Further, the present invention provides a first contour compensating means for compensating an input video signal for a contour from a luminance change portion;
A display means for driving a plasma display panel to display a signal from the contour compensating means, and a second contour compensating means for performing transient compensation on a pixel-by-pixel basis with the display means. Is displayed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a scanning conversion means for scan-converting a change in luminance when a vertical scanning frequency changes, to a vertical scanning frequency of an input signal, and a gamma correction after a luminance correction corresponding to a two-dimensional spatial position. And a method of driving a plasma display panel capable of eliminating a change in luminance due to a vertical scanning frequency and displaying an image with high fidelity and sharpness. It has the effect that it can be realized.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing a driving method of a plasma display panel (hereinafter abbreviated as PDP) according to the present invention. In FIG. 1, 1 designates an input terminal of an input video signal and 2 designates an input signal. Is a sub-field forming unit for realizing gradation expression in the PDP, and 4 is a driving unit for driving a PDP 5 as a display device. Reference numeral 6 denotes a PDP driving unit including a sub-yield forming unit and a driving unit.

The PDP of the present embodiment configured as described above
2 will be described below with reference to an operation waveform diagram of FIG. 2 and an issuance characteristic diagram of FIG.

The input terminal 1 has five scanning lines as shown in FIG.
For example, an NTSC video signal having a vertical scanning frequency of 60 Hz and an NTSC signal of 25 is supplied to the scan converter 2 and converted into a signal corresponding to the number of PDP pixels (640 × 480 pixels) shown in FIG. The signal from the scan conversion unit is transmitted to a PD constituted by a subfield forming unit 3 and a driving unit 4.
The P drive unit 6 creates a PDP drive waveform shown in FIG. 2B, and displays an NTSC image on the PDP. The luminance emission characteristics (vs vertical scanning frequency) at this time are shown in FIG.
The PDP drive waveform shown in FIG. 2B is composed of subfields (hereinafter, abbreviated as SF) 1 to 8.

Next, when a PAL video signal having 625 scanning lines and a vertical scanning frequency of 50 Hz is input to the input terminal 1 as shown in FIG. 2C, normal processing is performed.
The PDP drive waveform shown in (d) is created, and PA
The L image is displayed. In this case, as is clear from the relative comparison between FIG. 2B and FIG. 2D, the emission ratio at the time of PAL is reduced in FIG. The brightness will decrease in inverse proportion to the frequency.

Accordingly, in the present application, the PDP signal shown in FIG. 2C is scanned and converted into the NTSC signal shown in FIG.
As shown by the broken line, a constant luminance can always be obtained even when the vertical scanning frequency changes.

Next, in order to explain the scan conversion operation in detail, a PDP pixel structure diagram of FIG. 4 and an operation flowchart of FIG. 5 will be used. FIG. 4 shows a PD composed of 640 × 480 pixels.
3 shows a P pixel structure. FIG. 5 shows the processing operation of the scan conversion at the time of NTSC and PAL. In the case of NTSC, only the pixel conversion is performed.
The pixel is converted after the scan conversion to Hz. Therefore, PAL
The signal is scan-converted by the vertical effective pixel 480 to a vertical scanning frequency of 60 Hz to drive the PDP, so that a decrease in luminance can be prevented.

Further, by converting the PAL signal into an NTSC signal in a pseudo manner, line flicker can be reduced, and high image quality can be realized at the same time.

In this embodiment, in order to make the explanation easy to understand, a case where all the signal sources are scan-converted into signals having a specific vertical scanning frequency has been described, and the luminance is kept constant as shown by the broken line in FIG. However, for example, it is also possible to perform scan conversion only at the time of PAL to suppress a decrease in luminance at the time of PAL as shown by a dashed line in FIG.

As described above, according to the present embodiment, the input signal is scan-converted and a PDP driving waveform is created using a signal converted to a predetermined vertical scanning frequency, so that a clear luminance with a constant brightness is always maintained. Image display can be realized.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a block diagram of a method of driving a PDP according to the second embodiment. In FIG. 6, the same portions as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. 6, reference numeral 8 denotes a luminance correction unit for modulating luminance by modulating a video signal, 9 denotes a correction signal generation unit for generating a correction signal of a two-dimensional spatial position of the luminance correction unit 8, and 10 denotes light emission characteristics of a PDP. Is a gamma correction unit that corrects gamma according to.

The operation of the driving method of the plasma display panel of the present embodiment configured as described above will be described below with reference to the display screen diagram of FIG. 7 and the emission characteristic diagram of FIG.

FIG. 7 shows a display screen of a DC type PDP.
For example, a dark horizontal line (hereinafter abbreviated as a dark line) is generated at the center of the screen due to a variation in cell resistance. In FIG. 8, a solid line indicates a normal part,
As shown by the dashed line, the light emission characteristic of the dark line portion, the cutoff and the gain are different. Therefore, the luminance correction unit 8 in FIG. 6 first performs an addition process for adjusting the cutoff in the vicinity of black to correct the light emission characteristics shown by the dashed line in FIG. 8, and then performs the second addition in the vicinity of white. By adjusting the gain, the light emission characteristics of the dark line part shown by the broken line in FIG. 8 are aligned with the normal part. Note that the correction signal generation unit 9 uses the cutoff correction signal shown in FIG.
The correction signal at the center of the screen of the gain correction signal shown in FIG.

After performing the dark line correction in the luminance correction section 8,
A uniform screen can be realized by performing gamma correction according to the light emission characteristics of the PDP in the gamma correction unit 10.

Next, the block diagram of FIG. 10 will be used to explain the luminance correction in detail. After the video signal from the input terminal 1 is clamped by the clamp circuit 11, the adder 1
In step 1, the cutoff correction signal from the cutoff correction signal generation circuit 14 is added to adjust the cutoff. Adder 12
From the gain correction signal generating circuit 15
The gain is adjusted by multiplying the video signal by the gain correction signal from the CPU. The luminance-corrected signal from the multiplier 13 is gamma-corrected by the gamma correction circuit 10 of, for example, γ = 2.2, thereby achieving good gradation.

As described above, according to the present embodiment, the PD
By performing the gamma correction after performing the luminance correction corresponding to the two-dimensional spatial position on the luminance unevenness caused by P, it is possible to realize a uniform and faithful image display of gradation. In particular, this is an effective means for a DC-PDP in which the cell resistance varies.

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 11 is a block diagram of a method of driving a PDP according to the third embodiment. In FIG. 11, the same portions as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. In FIG. 11, reference numeral 6 denotes a first contour compensator for performing contour compensation from a luminance change portion of a video signal, 17 an A / D converter for converting an analog signal into a digital signal, and 18 a P / D
This is a second contour compensator that performs high-speed waveform response compensation (hereinafter abbreviated as transient compensation) in DP pixel units.

The operation of the method of driving the plasma display panel of the present embodiment configured as described above will be described below with reference to the MTF characteristic diagram of FIG. 12 and the boost frequency characteristic diagram of FIG.

In general, the spot shape of a CRT has a Gaussian distribution, so that an MTF having a falling characteristic as shown by a broken line in FIG. 12 is shown. Therefore, a driving process suitable for a PDP different from a CRT is required.

For this reason, the first contour compensator 16 performs contour compensation at a low boost frequency (f3) as shown by the solid line in FIG. 13 as in the prior art, and the second contour compensator 18 performs high boost as shown by the broken line in FIG. By performing contour compensation at the frequency (f4), a clear image display is realized.

Since the PDP is an all-digital drive system, the main cause of image quality deterioration is the signal S / N. If the signal S / N deteriorates, it appears as deterioration in basic performance such as gradation, resolution, and false contour.

Therefore, a digital second contour compensator 18 for performing stable transient correction with little S / N deterioration is newly provided in the conventional analog contour compensator (first contour compensator 16). , PDP.

As a result, the sharpness can be greatly improved as compared with the CRT, and a good processing of the signal S / N can be realized. In the first contour compensation, the boost frequency is changed according to the input signal source (for example, 2 MHz for NTSC, 8 MHz for HDTV, etc.). However, the second contour compensation performs transient correction in PDP pixel units. , Is always set to a constant boost frequency. In particular, by performing contour compensation in a high band where the signal S / N is significantly deteriorated by digital processing, transient compensation can be performed without deterioration of the signal S / N by the coring technique.

Next, in order to describe the transient compensation in detail, an operation waveform diagram of FIG. 14 and a frequency characteristic diagram of FIG. 15 will be used.

With a wideband signal as shown by the broken line in FIG. 15, a rectangular waveform response as shown in FIG. 14 (a) can be realized. However, the band is actually limited as shown by the solid line in FIG. A gentle mountain-shaped waveform response shown in FIG. By performing the first contour compensation on the waveform of FIG. 14B, contour compensation is performed at the boost frequency f4 indicated by the one-dot broken line in FIG. 15 to obtain an aperture-compensated signal shown in FIG. 14B. However, the waveform response is largely different from the waveform response in which the band is not limited in FIG. Therefore, by performing the transient compensation, which is the second contour compensation for each pixel of the PDP, the steep waveform shown in FIG. 14D realizes the waveform response, and the sharpness is greatly improved.

As described above, according to the present embodiment, the contour compensation having a boost frequency half that of the conventional band and PD
By using digital contour compensation that performs transient compensation in units of P pixels, an image display with high fidelity and high sharpness can be realized.

In this embodiment, a driving method using a display device using a PDP has been described for easy understanding, but it goes without saying that the present invention is also effective for other display devices.

[0040]

According to the driving method of the plasma display panel of the present invention, the input signal is scan-converted to generate a PDP driving waveform with a signal converted to a predetermined vertical scanning frequency, so that the luminance is always kept constant. It is possible to realize the display of the kept clear image. Also, PAL having a particularly low vertical scanning frequency
Since it is easy to achieve high image quality by reducing flicker in a signal, it can be realized with a simple configuration.

Further, according to the driving method of the plasma display panel of another invention, the gamma correction is performed after the luminance correction corresponding to the two-dimensional spatial position is performed.
Brightness correction can be realized with high accuracy, and a uniform image can be displayed.

Further, according to the plasma display panel driving method of another invention, the first contour compensation for performing contour compensation on an input video signal from a luminance change portion and the transient compensation for each pixel in the plasma display panel are performed. By performing in combination with the second contour compensation to perform,
Since good S / N processing can be realized, very faithful and high-sharpness image display can be realized, and the practical effect is large. This is a driving method particularly suitable for a PDP.

[Brief description of the drawings]

FIG. 1 is a block diagram of a driving method of a plasma display panel according to a first embodiment of the present invention;

FIG. 2 is an operation characteristic diagram for explaining the operation of the first embodiment.

FIG. 3 is an issuance characteristic diagram for explaining the operation of the first embodiment;

FIG. 4 is a PD for explaining the operation of the first embodiment.
P pixel configuration diagram

FIG. 5 is an operation flowchart for explaining the operation of the first embodiment;

FIG. 6 is a block diagram of a driving method of a plasma display panel according to a second embodiment of the present invention.

FIG. 7 is a display screen diagram for explaining the operation of the second embodiment.

FIG. 8 is a light emission characteristic diagram for explaining the operation of the second embodiment.

FIG. 9 is an operation waveform diagram for explaining a correction operation according to the second embodiment.

FIG. 10 is a detailed block diagram for explaining the operation of the second embodiment;

FIG. 11 is a block diagram of a driving method of a plasma display panel according to a third embodiment of the present invention.

FIG. 12 is a diagram illustrating M for explaining the operation of the third embodiment;
TF characteristic diagram

FIG. 13 is a boost frequency characteristic diagram for explaining the operation of the third embodiment.

FIG. 14 is an operation waveform diagram for explaining the operation of the third embodiment.

FIG. 15 is a frequency characteristic diagram for explaining the operation of the third embodiment.

[Explanation of symbols]

 Reference Signs List 2 scan conversion unit 3 subfield generation unit 4 drive unit 5 PDP 8 luminance correction unit 9 correction signal generation unit 10 gamma correction unit 16 first contour compensation unit 18 second contour compensation unit

Claims (6)

[Claims] A scan conversion unit that scan-converts an input video signal into a signal having a predetermined vertical scanning frequency; and a display unit that drives a plasma display panel with a signal from the scan conversion unit to display an image. A method for driving a plasma display panel, characterized in that control is performed so as to obtain a constant screen luminance even when a vertical scanning frequency of an input video signal changes. 2. The method according to claim 1, wherein the control means scan-converts a signal having a low vertical scanning frequency into a signal having a predetermined vertical scanning frequency. 3. A luminance correction means for correcting the luminance of an input video signal at a two-dimensional spatial position, a gamma correction means for performing gamma correction with a signal from the luminance correction, and a plasma display panel using a signal from the gamma correction means. A driving method for a plasma display panel, comprising: display means for driving to display an image. 4. The driving method for a plasma display panel according to claim 3, wherein the luminance correction stage corrects the luminance by adding and multiplying the video signal by a two-dimensional correction signal. 5. A first contour compensation means for compensating contours of an input video signal from a luminance change portion, and a signal from said first contour compensation means drives a plasma display panel as a display device to display an image. A driving method for a plasma display panel, comprising: a display unit; and a second contour compensation unit for performing transient compensation in pixel units of the display device. 6. The apparatus according to claim 5, wherein the first and second contour compensation means set the second boost frequency higher than the first boost frequency to perform transient compensation. Driving method of a plasma display panel.