KR20030045214A - Method Of Driving Plasma Display Panel And Apparatus Thereof - Google Patents

Abstract

The present invention relates to a method and apparatus for driving a plasma display panel capable of improving image quality.

The driving apparatus of the plasma display panel according to the present invention includes a signal discrimination unit detecting a frequency of an input signal, a memory in which driving modes are selected differently according to the frequency of the input signal, and a driving mode selected according to the detected frequency. And a signal processor for determining a driving waveform and subfield arrangement for displaying an input signal.

Description

Method and device for driving plasma display panel {Method Of Driving Plasma Display Panel And Apparatus Thereof}

The present invention relates to a plasma display panel, and more particularly, to a method and apparatus for driving a plasma display panel capable of improving image quality.

Plasma Display Panel (hereinafter referred to as "PDP") displays an image including text or graphics by emitting phosphors by 147 nm ultraviolet rays generated during discharge of He + Xe or Ne + Xe inert mixed gas. . Such a PDP is not only thin and easy to enlarge, but also greatly improved in quality due to recent technology development. In particular, the three-electrode AC surface discharge type PDP has advantages of low voltage driving and long life because wall charges are accumulated on the surface during discharge and protect the electrodes from sputtering caused by the discharge.

As shown in FIG. 1, the driving apparatus of the PDP includes a signal processor 20 connected between the input line 1 of the video signal and the PDP 14.

The signal processor 20 includes a gamma correction unit 2 connected to an input line 1 of a video signal, a gain adjusting unit 4 and an error diffusion unit connected between the gamma correction unit 2 and the PDP 12. 6) a subfield mapping unit 8, an average picture level (hereinafter referred to as " APL ") calculation unit 10 and a waveform generation unit 12;

The gamma correction unit 2 inversely gamma corrects the video signal supplied from the input line 1 to linearly convert the luminance value according to the gray value of the image signal.

The gain adjusting unit 4 converts the gradation range of the video signal RGB into a preset gradation range according to the luminance information from the gamma correction unit 2.

The error diffusion unit 6 finely adjusts the luminance value by diffusing an error component of the cell into adjacent cells.

The subfield mapping unit 8 stores a plurality of pieces of subfield information for which luminance weights are set, and maps data input from the error diffusion unit 6 to subfields.

The data aligning unit (not shown) converts the video data input from the subfield mapping unit 8 to the PDP 14 in accordance with the resolution format of the PDP 14.

The APL calculation unit 10 receives the data inversely gamma corrected by the gamma correction unit 2 and supplies a signal for determining the number of sustain pulses to the waveform generation unit 12 according to the gray level preset for the data. Done.

The waveform generator 12 generates a timing control signal based on the signal input from the APL unit 10, and outputs the generated timing control signal to an address driving IC (not shown) and a scan driving IC (not shown) of the PDP 14. And sustain drive ICs (not shown).

The PDP 14 drives one frame by dividing one frame into several subfields with different number of emission times in order to express the gray level of the image. Each subfield is further divided into a reset period for uniformly generating discharge, an address period for selecting a discharge cell, and a sustain period for implementing gray levels according to the number of discharges. When the image is to be displayed with 256 gray levels, a frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields SF1 to SF8 as shown in FIG. Each of the eight subfields SF1 to SF8 is divided into a reset period, an address period, and a sustain period. The reset period and the address period of each subfield are the same for each subfield, while the sustain period and the number of discharges thereof are 2 ⁿ in each subfield as shown in FIG. 3 (where n = 0,1,2,3 , 4,5,6,7). In this way, since the sustain period is changed in each subfield, the gray level of the image can be expressed.

Conventional video signals include NTSC (National Television System Committe) signals with a frequency of 60 Hz, phase alternating by line (PAL) signals with a frequency of 50 Hz, and PC images with a frequency of 70 Hz.

In the conventional PDP driving apparatus for inputting such a video signal, a method having a constant driving waveform and subfield arrangement regardless of the video signal has been used. Accordingly, contour noise or flicker may be generated for the specific input signal. If pseudo contour noise or flicker occurs, there is a problem that the image quality is degraded.

Accordingly, an object of the present invention is to provide a driving apparatus and a driving method of a plasma display panel which can improve image quality.

1 is a view showing a driving apparatus of a conventional plasma display panel.

2 is a diagram illustrating a conventional frame including eight subfields in a method of driving a conventional plasma display panel.

3 is a diagram showing luminance weighting values of video data during a conventional subfield period;

4 is a view showing a driving device of a plasma display panel according to the present invention;

5A-5C illustrate a method of rearranging subfields to remove flicker.

<Description of Symbols for Main Parts of Drawings>

1,31 Input line 2,32 Gamma correction

4,34: gain adjustment unit 6,36: error diffusion unit

8,38: subfield mapping unit 10,40: APL calculation unit

12,42: waveform generator 14,44: PDP

20,50: signal processing section 46: signal discriminating section

48: EPROM

In order to achieve the above object, a driving apparatus of a plasma display panel according to the present invention includes a signal discriminating unit for detecting a frequency of an input signal, a memory in which driving modes are selected differently according to the frequency of the input signal, and detected. And a signal processor for selecting a driving mode according to the frequency and determining a driving waveform and subfield arrangement for displaying an input signal.

The memory is characterized in that it is formed of EPROM.

In order to achieve the above object, a driving method of a plasma display panel according to the present invention includes detecting a frequency of an input signal, arranging a driving waveform and a subfield for displaying an input signal by selecting a driving mode according to the detected frequency. Determining a step.

When the input signal is detected as a PAL (Phase Alternating by line) signal, the subfield arrangement is characterized in that the center of the light amount has two or more peak values.

When the input signal is detected as a signal of the National Television System Committe (NTSC) method, the number of subfields is increased.

When the input signal is detected as a PC image, the number of gray levels or the number of colors is increased.

Other objects and features of the present invention in addition to the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 5C.

Referring to FIG. 4, the driving apparatus of the PDP according to the present invention is a signal discrimination unit 46 connected to the input line 31 of the video signal, and a signal connected between the signal discrimination unit 46 and the PDP 44. A processor 50 and an Epyrom (Erasable and Programmable Read Only Memory) hereinafter referred to as " EPROM "

The signal processing unit 50 calculates the gamma correction unit 32, the gain adjusting unit 34, the error diffusion unit 36, and the subfield mapping unit 38, and an average picture level (hereinafter referred to as "APL"). A unit 40 and a waveform generator 42 are provided.

The signal discriminator 46 detects a frequency or a period to determine a video signal input through the input line 31. That is, the signal discriminator 46 determines a PAL (Phase Alternating by Line) signal when the frequency is 50 Hz, a NTSC (National Television System Committe) signal when the frequency is 60 Hz, and a PC image when the frequency is 70 Hz. The gamma correction unit 32 and the EPROM 48 are supplied.

The EPROM 48 has a built-in lookup table (not shown) recorded with respect to the driving mode of the video signal determined from the signal discriminating section 46. The driving waveform and the subfield arrangement corresponding to the determined video signal are transmitted to the subfield mapping unit 38 and the waveform generator 42.

The gamma correction unit 32 performs inverse gamma correction on the video signal determined from the signal discriminator 46 to linearly convert the luminance value according to the gray value of the video signal.

The gain adjusting unit 34 converts the gradation range of the video signal RGB into a preset gradation range according to the luminance information from the gamma correction unit 32.

The error diffusion unit 36 finely adjusts the luminance value by diffusing an error component of a cell into adjacent cells.

The subfield mapping unit 38 stores a plurality of pieces of subfield information having luminance weights set to map data input from the error diffusion unit 36 and the EPROM 48 to the subfields.

The data aligning unit (not shown) converts the video data input from the subfield mapping unit 38 to the PDP 44 in accordance with the resolution format of the PDP 44.

The APL calculation unit 40 receives the inverse gamma corrected data by the gamma correction unit 32, and waveforms a signal for determining the number of sustain pulses corresponding to the data corrected by the EPROM 48. It is supplied to the generating part 42.

The waveform generator 42 generates a timing control signal based on the signals input from the EPROM 48 and the APL calculation unit 40, and generates the address control IC (not shown) of the PDP 44. And a scan driving IC (not shown) and a sustain driving IC (not shown).

5A to 5C are diagrams illustrating driving waveforms and subfield arrangements according to video signals input to the PDP driving apparatus of the present invention.

If the video signal determined by the signal discriminator 46 is a PAL signal (50 Hz), the PAL signal has a period of about 20 ms to increase the number of subfields to 14 to 16, thereby reducing pseudo contour noise. Although it can be removed, there is a problem that flicker occurs. In order to eliminate this flicker, the subfield is made so that the center of light amount has two or more peak values. For example, as shown in FIG. 5A, 1: 4: 16: 16: 16: 16: 16: 32: 2: 8: 16: 16: 16: 16: 32: 32, as shown in FIG. 5B. Likewise, 32: 16: 16: 16: 16: 16: 4: 1: 32: 32: 16: 16: 16: 16: 8: 2, or as shown in Figure 5c, 1: 16: 16: 16 : 32: 16: 16: 4: 2: 16: 16: 32: 32: 16: 16: 8

If the video signal determined by the signal discriminator 46 is an NTSC signal (60 Hz), the signal of the NTSC method increases the number of subfields to remove pseudo contour noise because the probability of occurrence of flicker is low. For example, the number of subfields is 12 and the total number of sustains is about 1200.

If the video signal determined by the signal discriminator 46 is a PC (70 Hz) video, the PC video signal has a period of about 14.28 ms, so that only about 10 subfields can be used, so the total number of sustains is 100. Limited to that extent. Therefore, the PC image of which the still image is mainstream is transformed around the number of gradations and the number of colors. For example, the conventional sustain ratio is 1: 2: 4: 8: 16: 32: 48: 48: 48: 48 so that it has 256 gradations, but in the present invention, 1: 2: 4: 8: 16: 32 : 48: 56: 69: 75 or 1: 2: 4: 10: 18: 34: 52: 63: 75: 84 so that the number of grays exceeds 256.

As described above, the driving apparatus of the plasma display panel according to the present invention uses the driving mode corresponding to the input signal, that is, the driving waveform and the subfield arrangement. Accordingly, pseudo contour noise and flicker can be removed, thereby making it possible to realize an optimal screen.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (6)

A signal discrimination unit detecting a frequency of the input signal; A memory in which driving modes selected differently according to the frequency of the input signal are stored; And a signal processor which selects the driving mode according to the detected frequency to determine a driving waveform and a subfield arrangement for displaying the input signal. The method of claim 1, And the memory is formed of EPROM. Detecting a frequency of the input signal; And selecting the driving mode according to the detected frequency to determine a driving waveform and a subfield arrangement for displaying the input signal. The method of claim 3, wherein And when the input signal is detected as a PAL (Phase Alternating by line) signal, subfield arrangement such that the center of the light amount has two or more peak values. The method of claim 3, wherein And when the input signal is detected as a NTSC signal, increasing the number of subfields. The method of claim 3, wherein And when the input signal is detected as a PC image, increasing the number of gradations or the number of colors.