KR100493915B1 - Method and apparatus for driving plasma display panel - Google Patents

Abstract

The present invention relates to a method and apparatus for driving a plasma display panel to reduce a wide area flicker phenomenon generated when processing an image of a 60 Hz video standard in a 50 Hz video standard.

The plasma display panel driving method and apparatus increases at least one of the scan pulse of the address period and the pulse width of the sustain pulse of the sustain period when the frame frequency is changed from 60 Hz to 50 Hz, and when the frame frequency is changed from 50 Hz to 60 Hz. The pulse width of the increased pulses is reduced to a reference value.

Description

Method and apparatus for driving plasma display panel {METHOD AND APPARATUS FOR DRIVING PLASMA DISPLAY PANEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a plasma display panel, and more particularly, to a method and apparatus for driving a plasma display panel to reduce a flicker phenomenon.

Recently, there is a growing interest in flat panel displays that can reduce the weight and volume of cathode ray tubes. Such flat panel displays include liquid crystal displays, plasma display panels (PDPs), field emission displays, and electro-luminescence, and digital signals. Alternatively, analog data is supplied to the display panel.

Among such flat panel display devices, the plasma display panel emits phosphors by 147 nm ultraviolet rays generated when the He + Xe, Ne + Xe or He + Xe + Ne gas is discharged to display images and video including characters or graphics. . The plasma display panel is not only thin and large in size, but also recently, due to technology development, the plasma display panel provides greatly improved image quality.

In particular, the three-electrode AC surface discharge type plasma display panel accumulates wall charges using a dielectric layer during discharging, thereby lowering the voltage required for discharging, and has advantages of low voltage driving and long life because it protects the electrodes from sputtering of plasma.

Referring to FIG. 1, a discharge cell of a three-pole current alternating current surface discharge plasma display panel is formed on a scan electrode 30Y and a sustain electrode 30Z formed on an upper substrate 10, and a lower substrate 18. The address electrode 20X is provided.

Each of the scan electrode 30Y and the sustain electrode 30Z has a line width smaller than the line widths of the transparent electrodes 12Y and 12Z and the transparent electrodes 12Y and 12Z, and the metal bus electrodes 13Y and 13Y formed at one edge of the transparent electrode. 13Z). Indium tin oxide (ITO) is generally used as a material of the transparent electrodes 12Y and 12Z. As the material of the metal bus electrodes 13Y and 13Z, a metal such as chromium (Cr) is usually used. The metal bus electrodes 13Y and 13Z serve to reduce voltage drop caused by the transparent electrodes 12Y and 12Z having high resistance. The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 on which the scan electrode 30Y and the sustain electrode 30Z are formed. In the upper dielectric layer 14, charged particles generated by gas discharge ionization gas (plasma) are accumulated. The protective layer 16 protects the upper dielectric layer 14 from sputtering of charged particles generated during gas discharge and increases the emission efficiency of secondary electrons. As the protective film 16, magnesium oxide (MgO) is usually used. The address electrode 20X is formed in a direction intersecting with the sustain electrode 30Y and the sustain electrode 30Z. The lower dielectric layer 22 and the partition wall 24 are formed on the lower substrate 18 on which the address electrode 20X is formed.

The phosphor layer 26 is formed on the surfaces of the lower dielectric layer 22 and the partition wall 24. The partition wall 24 is formed to be parallel to the address electrode 20X to physically distinguish the discharge cells, and prevent ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 26 is emitted by ultraviolet rays generated during gas discharge to generate visible light of any one of red (R), green (G), and blue (B). An inert mixed gas such as He + Xe, Ne + Xe or He + Xe + Ne for discharging is injected into the discharge space provided between the upper and lower substrates 10 and 18 and the partition wall 24.

The three-electrode AC surface discharge type plasma display panel is driven by dividing one frame into several subfields having different emission counts in order to realize gray levels of an image. Each subfield is further divided into a reset period for generating discharge uniformly, an address period for selecting a Banggen cell, and a sustain period for implementing gray levels according to the number of discharges. When the image is to be displayed with 265 gray levels, a frame period (16.67 ms) corresponding to 1/60 second is divided into a plurality of subfields. Each of the plurality of subfields 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 (where n = 0, 1, 2, 3, 4, 5, 6, 7) is increased in proportion. In this way, gray levels can be implemented by using a combination of subfields having different sustain periods.

2 is a view showing an actual driving waveform for driving such a three-electrode plasma display panel. In FIG. 2, X represents a data electrode, Y represents a scan electrode, and Z represents a signal waveform supplied to the sustain electrode.

Referring to FIG. 2, the plasma display panel is driven by dividing into a relet period for initializing the full screen, an address period for selecting a cell, a sustain period for maintaining the discharge of the selected cell, and an erase period.

In the reset period, the rising ramp waveform RAMP-UP is applied to all the scan electrodes Y simultaneously. The rising ramp waveform causes a priming discharge to occur between the scan electrode (Y) and the address electrode (X) and between the scan electrode (Y) and the sustain electrode (Z) in the cells of the full screen. Due to the priming discharge, positive wall charges are accumulated on the address electrode X and the sustain electrode Z, and negative wall charges are accumulated on the scan electrode Y.

During the set-down period, after the ramp ramp waveform becomes high, the ramp ramp begins to fall from the positive voltage lower than the peak voltage of the ramp ramp and then falls to the base voltage (GND) or a specific voltage level of the negative ramp (RAMP-DOWN). It is applied to these scan electrodes Y simultaneously. At the same time, a positive sustain voltage Vs is applied to the sustain electrode Z which is a common electrode, and 0 [V] is applied to the address electrode X. When the falling ramp waveform is applied, a setdown discharge is generated between the scan electrode Y and the sustain electrode Z. This set-down discharge eliminates excessive wall charges unnecessary for the address discharge among the wall charges generated during the setup period.

In the address period, the negative scan pulses are sequentially applied to the scan electrodes Y, and the positive data pulses are applied to the address electrodes X in synchronization with the scan pulses. As the voltage difference between the scan pulse and the data pulse and the wall voltage due to the wall charge generated during the reset period are added, an address discharge is generated in the cell to which the data pulse is applied. In the cells selected by the address discharge, wall charges such that discharge can occur when the sustain voltage Vs is applied are formed.

On the other hand, the sustain electrode Z is supplied with a positive DC voltage so as to reduce the voltage difference between the scan electrode Y during the set-down period and the address period so as to prevent erroneous discharge from the scan electrode Y.

In the sustain period, a sustain pulse is applied to the scan electrodes Y and the sustain electrodes Z alternately. In the cell selected by the address discharge, the sustain voltage, that is, the display discharge, is generated between the scan electrode Y and the sustain electrode Z every time the sustain pulse is applied as the wall voltage and the sustain pulse in the cell are added.

In the erasing period, a ramp waveform RAMP ERS having a small pulse width and a low voltage level is supplied to the sustain electrode Z to erase wall charges remaining in the cells turned on by the sustain discharge.

Flickering is a phenomenon in which the screen flickers or flickers with the naked eye. This flicker phenomenon is caused by the periodic change in brightness. In other words, the flicker phenomenon is caused by the periodic change of the lighting period and the non-lighting period VFB of the screen.

NTSC, which is used in North America, operates by dividing 1 second into 60 frames when displaying an image. In contrast, the European video standard (PAL) runs by dividing one second into 50 frames. When the subfield codes and driving waveforms designed for the 60Hz video standard method (NTSC) are applied to the 50Hz video standard method (PAL) as they are, the non-display period is further increased, thereby causing flicker on the screen.

3 is a diagram illustrating a lighting period and a non-lighting period of a 60 Hz and 50 Hz video standard system.

Referring to Fig. 3, one frame is composed of a reset and an address period, a sustain period, and a non-display period VFB. In the 60 Hz video standard, the duration of one frame is 16.67 ms divided by 1 second divided by 60 Hz. In contrast, in the 50Hz video standard, the duration of one frame is 20ms divided by 50 by 1 second.

If the subfield code of 60Hz video standard with 16.67ms duration is applied to 50Hz video standard with 20ms duration of one frame, the non-lighting period (VFB) increases relatively in 50Hz video standard. . As such, when the non-lighting period is increased, flicker occurs on the screen, thereby degrading the display quality of the image. Furthermore, if the driving waveform designed based on the 60Hz video standard method is applied to the 50Hz video standard method as it is, the luminance is lowered by the increase in the non-lighting time (VFB). Furthermore, if the driving waveform designed based on the 60Hz video standard is applied to the 50Hz video standard as it is, the 50Hz video standard increases the non-lighting time (VFB) more than the 60Hz video standard. The change in power consumption becomes larger between the effective subfield period during which the discharge occurs and the non-lighting time (VFB).

Accordingly, an object of the present invention is to provide a method and apparatus for driving a plasma display panel to reduce the flicker phenomenon.

In order to achieve the above object, a method of driving a plasma display panel according to an embodiment of the present invention comprises the steps of detecting a frame frequency, and when the detected frame frequency is changed from 60Hz to 50Hz and the scan pulse of the address period and the Increasing at least one of the pulse widths of the sustain pulses in the sustain period; Decreasing the pulse width of the increased pulses to a reference value when the detected frame frequency is changed from 50 Hz to 60 Hz. According to another aspect of the present invention, there is provided a method of driving a plasma display panel, the method comprising: detecting a frame frequency, increasing the number of pulses of the sustain pulse in the sustain period when the detected frame frequency is changed from 60 Hz to 50 Hz; ; Reducing the number of pulses of the sustain pulse to a reference value when the detected frame frequency is changed from 50 Hz to 60 Hz. An apparatus for driving a plasma display panel according to an embodiment of the present invention includes a mode detector for detecting a frame frequency and a scan pulse of the address period and a sustain pulse of the sustain period when the detected frame frequency is changed from 60 Hz to 50 Hz. A timing controller for increasing at least one of the pulse widths and for reducing the pulse widths of the increased pulses to a reference value when the detected frame frequency is changed from 50 Hz to 60 Hz, and the pulses in the plasma display panel under the control of the timing controller; And a driving circuit for supplying them. According to another exemplary embodiment of the present invention, a driving apparatus of a plasma display panel includes a mode detector for detecting a frame frequency and an increase in the number of pulses of the sustain pulse in the sustain period when the detected frame frequency is changed from 60 Hz to 50 Hz. And a timing controller for reducing the number of pulses of the sustain pulse to a reference value when the detected frame frequency is changed from 50 Hz to 60 Hz, and a driving circuit for supplying the pulses to the plasma display panel under the control of the timing controller.

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

Hereinafter, a driving method and apparatus of a plasma display panel according to the present invention will be described in detail with reference to FIGS. 4 to 7.

4 is a view showing a method of reducing the flicker phenomenon according to the first embodiment of the present invention.

Referring to FIG. 4, in the driving method of the plasma display panel according to the first embodiment of the present invention, when the frame frequency is changed from 60 Hz to 50 Hz, the width of the sustain pulse of the driving waveform designed based on 60 Hz is increased. For example, if the width of the sustain pulse designed based on the 60 Hz video standard method is 5 μs, the width of the sustain pulse is varied to 5 μs + α when the frame frequency is reduced to 50 Hz, thereby increasing the pulse width by α compared to the 60 Hz reference pulse width. Therefore, when the frame frequency is changed from 60 Hz to 50 Hz, the non-illumination time VFB is reduced by the increase in the pulse width of the sustain pulse as compared with the case where there is no change in the pulse width.

Increasing the width of the sustain pulse results in a more stable sustain discharge and a sufficient amount of wall charge, which can reduce external sustain voltage and increase sustain margin.

In addition, the driving method of the plasma display panel according to the first embodiment of the present invention reduces the width of the sustain pulse increased to the reference pulse width when the frame frequency is changed from 50 Hz to 60 Hz.

5 is a view showing a method of reducing the flicker phenomenon according to the second embodiment of the present invention.

Referring to FIG. 5, the driving of the plasma display panel according to the second embodiment of the present invention further increases the number of sustain pulses of the driving waveform designed based on 60 Hz when the frame frequency is changed from 60 Hz to 50 Hz. For example, if the number of sustain pulses designed based on the 60Hz video standard is 32, the number of sustain pulses is changed to 32 + β when the frame frequency is reduced to 50Hz, increasing the number of pulses by β compared to the number of 60Hz reference pulses. Let's do it. Therefore, when the frame frequency is changed from 60 Hz to 50 Hz, the non-lighting time VFB decreases as the number of sustain pulses increases.

In addition, in the method of driving the plasma display panel according to the second embodiment of the present invention, when the frame frequency is changed from 50 Hz to 60 Hz, the number of increased pulses is reduced to the number of reference pulses in the 50 Hz video standard method.

6 is a view showing a method of reducing the flicker phenomenon according to a third embodiment of the present invention.

Referring to FIG. 6, the driving of the plasma display panel according to the third embodiment of the present invention increases the width of the scan pulse of the driving waveform designed based on 60 Hz when the frame frequency is changed from 60 Hz to 50 Hz. For example, if the width of the sustain pulse designed based on the 60 Hz video standard method is 3 μs, the width of the sustain pulse is changed to 3 μs + γ when the frame frequency is lowered to 50 Hz, thereby increasing the pulse width by γ compared to the 60 Hz reference pulse width. Accordingly, when the frame frequency is changed from 60 Hz to 50 Hz, the non-illumination time VFB is reduced by the increase in the pulse width of the scan pulse as compared with the case where there is no change in the pulse width.

As the width of the scan pulse increases, address discharge occurs more stably and a sufficient amount of wall charge is generated, thereby reducing external scan voltage or external data voltage and increasing address margin.

In addition, the driving method of the plasma display panel according to the third embodiment of the present invention reduces the width of the increased scan pulse to the reference pulse width when the frame frequency is changed from 50 Hz to 60 Hz.

7 is a block diagram illustrating a configuration of a plasma display panel driving apparatus according to embodiments of the present invention.

Referring to FIG. 7, the plasma display panel driving apparatus includes a data driver 48 for driving the address electrode X of the plasma display panel, and a scan / sustain driver for driving the scan electrode Y of the plasma display panel. 51), the common sustain driver 52 for driving the sustain electrode Z of the plasma display panel, the mode detector 49 for detecting the mode of the input image signal, and the driving timing of the plasma display panel. Timing controller 47, gamma correction unit 41, automatic gain control unit 42, error diffusion unit 43, subfield mapping unit 44, frame memory 45, drive An IC data sorting unit 46 is provided.

The data driver 48 includes a plurality of data drive ICs each connected to a predetermined number of address electrodes X under the control of the timing controller 47 to supply data to the address electrodes X.

The scan driver 51 is connected to the scan electrodes Y under the control of the timing controller 47 to simultaneously supply the reset pulse (or the setup pulse) to the scan electrodes Y. In addition, the scan driver 51 sequentially supplies the scan pulses to the scan electrodes Y in the address period, and then simultaneously supplies the sustain pulses to the scan electrodes Y in the sustain period.

The common sustain driver 52 is commonly connected to the sustain electrodes Z under the control of the timing controller 47 to simultaneously supply the sustain pulses to the sustain electrodes Z.

The mode detector 49 detects the frame frequency using the input digital video data R, G, and B and horizontal and vertical synchronization signals, and determines whether the frame frequency of the currently input image is 60 Hz or 50 Hz.

The timing controller 47 generates timing control signals for controlling the number of scan and sustain pulse widths and the number of sustain pulses that vary according to the frame frequency in response to the frame frequency detected by the mode detector 49 and transmit the timing control signals to the data driver. 48, the scan driver 51 and the sustain driver 52 are supplied.

The gamma correction unit 41 gamma-corrects the video signal to linearly change the luminance value according to the gray value of the video signal.

The automatic gain adjusting unit 42 converts the gradation range of the input data R, G, and B into a preset gradation range according to the luminance information from the gamma correction unit 41 to uniformly compensate the gain of the input data. It will play a role.

The error diffusion unit 43 serves to finely adjust the luminance value by assuring the error components to adjacent cells. To this end, the error diffusion unit 43 separates the data into the integer and the fractional part and multiplies the fractional part by a Fly-Steinberg coefficient to spread the error to adjacent cells.

The frame memory 45 stores data from the subfield mapping unit 44 in units of frames. The drive-specific IC data sorter 46 rearranges the data input from the frame memory 45 corresponding to each data drive IC and supplies the data to the data driver 48.

The subfield mapping unit 44 maps the data from the error diffusion unit 43 to the subfield. The data mapped for each subfield is assigned the lowest bit to the subfield in which the minimum luminance weight is set and the most significant bit to the subfield in which the maximum luminance weight is set.

As described above, the method and apparatus for driving the plasma display panel of the present invention further reduce the non-lighting time by further increasing the pulse width or number of driving waveforms when changing from the 60 Hz video standard method to the 50 Hz video standard method. As a result, the method and apparatus for driving the plasma display panel of the present invention can minimize the non-illumination period when the frame frequency is changed from 60 Hz to 50 Hz, thereby increasing the luminance, reducing the change in power consumption, and address margin and sustain margin. This improves address and sustain operations even under high and low temperature conditions.

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.

1 is a perspective view showing a discharge cell structure of a three-electrode AC surface discharge type plasma display panel.

2 is a view showing a driving waveform of the plasma display panel.

3 is a diagram illustrating a lighting period and a non-lighting period of 60 Hz and 50 Hz video standard methods.

4 is a view showing a method of reducing the flicker phenomenon according to the first embodiment.

5 is a view showing a method of reducing the flicker phenomenon according to the second embodiment.

6 is a view showing a method of reducing the flicker phenomenon according to the third embodiment.

7 is a block diagram showing the configuration of a plasma display panel driving apparatus according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: upper substrate 18: lower substrate

Y: scan electrode Z: sustain electrode

X: address electrode 12Y, 12Z: transparent electrode

13Y, 13Z: metal bus electrode 14: upper dielectric layer

16: protective film 22: lower dielectric layer

24: partition 26: phosphor layer

41: Gamma Compensation Government 42: Automatic Gain Control Unit

43: error diffusion unit 44: subfield mapping unit

45: frame memory 46: data alignment unit by drive IC

47: timing controller 48: data driver

49: mode detector 51: scan driver

52: sustain drive unit

Claims (10)

A driving method of a plasma display panel which displays an image by dividing the image into a plurality of subfields each including a reset period, an address period, and a sustain period for one frame period. Detecting a frame frequency; Increasing at least one of a scan pulse of the address period and a pulse width of the sustain pulse of the sustain period when the detected frame frequency is changed from 60 Hz to 50 Hz; And decreasing the pulse width of the increased pulses to a reference value when the detected frame frequency is changed from 50 Hz to 60 Hz. delete delete A driving method of a plasma display panel which displays an image by dividing the image into a plurality of subfields each including a reset period, an address period, and a sustain period for one frame period. Detecting a frame frequency; Increasing the number of pulses of the sustain pulse in the sustain period when the detected frame frequency is changed from 60 Hz to 50 Hz; And decreasing the number of pulses of the sustain pulse to a reference value when the detected frame frequency is changed from 50 Hz to 60 Hz. delete A driving apparatus of a plasma display panel which displays an image by dividing the image into a plurality of subfields each including a reset period, an address period, and a sustain period for one frame period. A mode detector for detecting frame frequency, Increase at least one of the scan pulse of the address period and the pulse width of the sustain pulse of the sustain period when the detected frame frequency is changed from 60 Hz to 50 Hz and the increase when the detected frame frequency is changed from 50 Hz to 60 Hz A timing controller for reducing the pulse width of the pulses pulsed to a reference value, And a driving circuit for supplying the pulses to the plasma display panel under the control of the timing controller. delete delete A driving apparatus of a plasma display panel which displays an image by dividing the image into a plurality of subfields each including a reset period, an address period, and a sustain period for one frame period. A mode detector for detecting frame frequency, To increase the number of pulses of the sustain pulse in the sustain period when the detected frame frequency is changed from 60Hz to 50Hz and to reduce the number of pulses of the sustain pulse to a reference value when the detected frame frequency is changed from 50Hz to 60Hz. With a timing controller, And a driving circuit for supplying the pulses to the plasma display panel under the control of the timing controller. delete