KR100278782B1 - Driving device of plasma display panel - Google Patents

Abstract

The present invention relates to a driving apparatus of a plasma display panel for maintaining a constant luminance level in response to multi-scan.

The apparatus for driving a plasma display panel according to the present invention includes a vertical frequency detecting means for detecting a vertical frequency of an input image signal, and adjusting the number of sustain pulses in the subfield so that the absolute value of the luminance level is constant corresponding to the detected vertical frequency. Sustain pulse number adjusting means is provided.

Description

Apparatus of Driving for Plasma Display Panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display device, and more particularly, to a driving device of a plasma display panel for maintaining a constant luminance level in response to multi-scan.

Recently, a liquid crystal display (hereinafter referred to as "LCD"), a field emission display (hereinafter referred to as "FED") and a plasma display panel (hereinafter referred to as "PDP") Flat display devices such as PDP have been actively developed. Among them, PDP is easy to manufacture due to its simple structure, high brightness and high luminous efficiency, memory function, and has a wide viewing angle of 160 ° or more, and realizes a large screen of 40 inches or more. It has the advantage of being able to. The PDP obtains a discharge through voltage control applied between vertical and horizontal electrodes of a cell constituting a pixel, and the amount of light discharged is controlled by changing the length of the discharge time in the cell. In other words, the PDP includes a write pulse for inputting a digital image signal to the vertical and horizontal electrodes of each cell, a scan pulse for scanning, a sustain pulse for maintaining a discharge, and a discharge. By applying an erase pulse for stopping the discharge of the cells, the cells are driven in a matrix form. Here, the step brightness required for image display, that is, gray scale, is expressed by implementing different lengths of time for discharging individual cells within a time when a screen of one frame is displayed. Such PDPs are generally classified into AC and DC types according to driving methods. Among the AC PDP driving methods, an ADS (Addressing Display Separated) driving method is a method of dividing and driving one frame into a plurality of subfields according to the gray scale to be implemented.

Referring to Figure 1, the configuration of one frame according to the conventional PDP driving method is shown. In general, one frame having a time of 1/60 second (Second) is composed of eight subfields to implement a 256-gradation image. Each subfield is composed of an address section and a sustain section. The address section of each subfield is a section for storing wall charges of pixels to be lit. In addition, the sustain section of each subfield is a section in which a sustain pulse is applied to the wall charges to cause sustain discharge only for cells in which address discharge has occurred, thereby determining a relative value of luminance. In general, one frame consists of eight subfields having different sustain periods to implement 256 gray levels. In this case, the sustain period in which the relative value of luminance is determined in the first to eighth subfields SF8 to SF8 is determined. The number of sustain pulses is allocated to 2048: 1024: 512: 256: 128: 64: 32: 16. The gray level of one frame is realized by the combination of the luminance determined in the sustain period of the first subfield SF1 to the eighth subfield SF8.

On the other hand, when a plasma display panel is connected to a personal computer (hereinafter referred to as a "PC") and used as a monitor, a multi-scan method corresponding to the vertical frequency of input PC image information is required. . In the case of using the multi-scan method, since the vertical frequency of the PC image information is changed according to the graphics mode (for example, the VGA mode, the SVGA mode, etc.), the interval of one frame is changed corresponding to the vertical frequency. That is, the number of light emission in one field per unit time increases or decreases as the vertical frequency increases or decreases, resulting in a change in luminance level. In this case, the relative value of the luminance between the subfields is maintained so that halftones can be expressed. However, the entire image within one frame is brightened or darkened. You lose.

Accordingly, an object of the present invention is to provide a driving apparatus of a plasma display panel to maintain a constant luminance level in response to multi-scan.

1 is a view showing the configuration of one frame for explaining a method of driving a plasma display panel according to the prior art.

2 is a block diagram showing a driving device of a plasma display panel according to the present invention;

3 is a diagram illustrating the configuration of one frame to explain a method of driving a plasma display panel according to the present invention;

4 is a view showing the configuration of one frame to explain a method of driving another plasma display panel according to the present invention.

<Description of Symbols for Main Parts of Drawings>

2: Synchronous Separator 4: Timing Pulse Generator

6: analog-to-digital converter 8: memory

10: memory controller 12: output processor

14: read timing pulse generator 16: vertical frequency detector

18,18 ': Scan and sustain pulse drive

20,20 ': Data pulse driver

In order to achieve the above object, a driving apparatus of a plasma display panel according to a first embodiment of the present invention includes vertical frequency detecting means for detecting a vertical frequency of an input image signal, and an absolute value of luminance level corresponding to the detected vertical frequency. Sustain pulse number adjusting means for adjusting the number of sustain pulses in the subfield to be constant.

In addition, the driving apparatus of the plasma display panel according to the second embodiment of the present invention includes a vertical frequency detecting means for detecting a vertical frequency of an input image signal, and a subfield so that the absolute value of the luminance level is constant corresponding to the detected vertical frequency. And a subfield number adjusting means for adjusting the number of.

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

With reference to Figures 2 to 4 will be described a preferred embodiment of the present invention.

Referring to FIG. 2, a driving apparatus of a plasma display panel according to the present invention includes an analog / digital converter (hereinafter, referred to as an “A / D converter”) connected to an input line, and an A / D converter ( A memory 8 connected to the output terminal of 6), a synchronous separator 2 connected to the input line, a timing pulse generator 4 and a vertical frequency detector 16 connected to the output terminal of the synchronous separator 2; ), A memory controller 10 connected to the output terminal of the timing pulse generator 4, a read timing generator 14 connected to the output terminals of the timing pulse generator 4 and the vertical frequency detector 16, An output processor 12 connected to the output of the memory 8 and the read timing generator 14, a data pulse driver 20, 20 'connected to the output of the output processor 12, and a read timing pulse generator. A scan pulse driver 18 and a sustain pulse driver 18 'connected to the output end of the motor 14 are provided. The sync separator 2 separates the horizontal and vertical sync signals included in the input video signal. The timing pulse generator 4 generates timing pulses by horizontal and vertical synchronization signals and outputs the timing pulses to the memory controller 10 and the read timing pulse generator 14. The A / D converter 6 digitizes the input video signal, converts it into 8-bit pixel data, and outputs it to the memory 8. The memory 8 temporarily stores pixel data. The memory controller 10 controls the memory 8 by the timing pulse signal to output the pixel data stored in the memory 8 to the output processor 12. The read timing pulse generator 14 generates various timing signals necessary for driving the PDP by timing pulses, and outputs them to the output processor 12, the scan pulse driver 18, and the sustain pulse driver 18 '. The output processor 12 outputs pixel data supplied from the memory 8 by the timing signal output from the read timing pulse generator 14 to the eight luminance values of the first subfield SF1 to the eighth subfield SF8. The components are separated into components and output to the data pulse driving units 20 and 20 '. The scan and sustain pulse drivers 18 and 18 'operate the discharge and sustain drive of the PDP by the timing signal output from the read timing pulse generator 14. For example, when the first subfield SF1 is scanned, the erase pulse is applied at a timing of 2048 discharge pulses and the erase pulse is applied after 1024 discharges in the second subfield SF2. . The data pulse drivers 20 and 20 'and the scan and sustain pulse drivers 18 and 18' scan electrodes of the pixels in the matrix panel in the order of the subfields to discharge the pixels into which the subfield data is input. The entire screen is driven to enable image display having a gray level. On the other hand, since the read timing pulse generator 14 can control only a certain timing, the number of discharges in the subfield is constant even if the vertical frequency of the input image changes. In the present invention, even if the vertical frequency of the input image is changed in the above configuration, the vertical frequency detection unit for detecting the vertical frequency output from the synchronous separator 1 for separating the input image into horizontal and vertical frequency signals to stabilize the brightness correspondingly. (16) is further provided to adjust the read timing pulse generator 14 by the detected vertical frequency. The operation of the read timing generator 14 will be described in detail. The read timing pulse generator 14 controls the sustain pulse at the time of erasing pulse generation so as to enable timing control by varying the number of discharges in the subfield according to the vertical frequency. The reason for considering luminance is that when it is changed to 72Hz based on 60Hz, the same number of discharges in the subfield has more discharges in unit time. Losing phenomenon will occur. That is, the timing of generation of the erase pulses for determining the number of discharges of the subfield is adjusted according to the detected vertical frequency, and the number of discharges in the subfield is appropriately adjusted even if the vertical frequency changes. Since the luminance in the subfield is not changed arithmetically by the number of discharges but also by the vertical frequency, the timing is controlled to have the number of discharges determined in consideration of all of them. Referring to FIG. 3, when the number of discharges in the eighth subfield SF8 is Y1 and the luminance at this time is L1, the number of discharges Y2 is determined so that the luminance in the seventh subfield SF7 is 2 × L1. do. In this way, the number of discharges of the subfields is also determined so that the luminance increases constantly. In consideration of the number of discharges corresponding to all input frequencies, multi-scanning is possible by simple timing control. Subfields can be displayed without changing luminance by changing the vertical frequency.

Referring to FIG. 4, when the vertical frequency is changed from 60 Hz to 72 Hz, instead of adjusting the number of sustain pulses, which are the number of discharges in the subfield, the number of subfields is adjusted to correspond to multiscan. If the vertical frequency is increased, the number of subfields can be displayed by reducing the number of subfields within a unit time. For example, at 60Hz, there are eight subfields in 1/60 second, but at 72Hz, the total display time is reduced, making it difficult to display eight subfields at 60Hz. Therefore, if the number of sustain pulses is kept as it is, the number of subfields can be reduced, and in this case, if the number of subfields is compensated by using the error diffusion method, the same gray level as before the subfield is reduced even though the number of subfields is two. The expression becomes possible. In the above embodiment, although the number of subfields is maintained even by maintaining the number of subfields by adjusting the number of discharges in the subfields, the present embodiment is intended to solve the problem by reducing the number of subfields. If the number of subfields is reduced, a complete gray level is not possible, but instead of reducing the number of subfields, it is possible to compensate for the intermediate gray level by using an error diffusion method, so that 256 gray levels can be realized. When the number of subfields is reduced, the number of necessary subfields corresponding to the vertical frequency and the number of discharges in each subfield are preset and stored in the output processor 12 and the scan and sustain pulse drivers 18 and 18 ', respectively. This is selected corresponding to the vertical frequency detected by the frequency detector 16 to drive the PDP in a subfield manner to realize a gray level having stable luminance.

As described above, the plasma display driving apparatus according to the present invention has a constant luminance corresponding to multi-scan by setting the number of sustain pulses or the number of subfields in which the luminance level detected in the image is kept constant according to the change in the vertical frequency. To maintain the level.

As described above, the driving apparatus of the plasma display panel according to the present invention has the advantage of maintaining a constant luminance level corresponding to the multi-scan.

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. For example, in the exemplary embodiments of the present invention, a case in which the vertical frequency of the image information is 72 Hz has been described. However, even when the vertical frequency is changed to correspond to the multi-scan, the driving apparatus according to the exemplary embodiments of the present invention may be applied. Those skilled in the art will appreciate. 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 (2)

In a driving apparatus of a plasma display panel in which one frame is divided into a plurality of subfields and sustain pulses are assigned to the subfields in different numbers according to luminance relative ratios, the vertical frequency of detecting the vertical frequency of the input image signal. And a frequency detecting means and a sustain pulse number adjusting means for adjusting the number of sustain pulses differently set in the subfields in correspondence with the detected vertical frequency. A driving apparatus for a plasma display panel in which one frame is divided into a plurality of subfields, the apparatus comprising: vertical frequency detecting means for detecting a vertical frequency of an input image signal, and being allocated in the one frame corresponding to the detected vertical frequency; And a subfield number adjusting means for adjusting the number of subfields.