KR100262827B1 - Method for driving three-electrodes surface-discharge plasma display panel - Google Patents

Abstract

PURPOSE: A driving method for a 3-electrode panel discharge plasma display panel is provided to increase a sustain frequency by using an erase pulse whose driving voltage is lower and the sustain time is shorter than a write pulse. CONSTITUTION: The device includes following steps. At first, 1 frame is divided into x sub fields. A number of sustain pulses applied to each sub field is adjusted so as to lay different weight on brightness level which is represented by the each sub field. A whole screen is divided into X sub-screens along with a horizontal line(H-line) and the X sub fields represent each sub field different from one another. An addressing step is performed by varying the sub filed of some lines for every period of the sustain fields so as for all cells of the whole screen to represent x sub fields once in turn. The addressing step for the lines whose sub fields are to be varied is performed as follows. The write pulse is applied at the same time. Then, the erase pulse is applied for each line sequentially. The frequency of the sustain pulse is increased.

Description

Driving method of 3-electrode surface discharge plasma display panel

The present invention relates to a method of driving a three-electrode surface discharge plasma display panel (hereinafter referred to as a three-electrode surface discharge PDP), and more particularly, to a method of expressing gray scale of an image.

The CRT (Cathode Ray Tube), which has been the mainstay of the display means, scans the electron beam through the entire fluorescent surface with a single electron gun, so the distance between the fluorescent surface and the electron gun must be large.

Due to the above characteristics, CRT is bulky, heavy, difficult to implement a flat screen, and difficult to realize a large screen.

Therefore, in order to overcome the problems of the CRT as described above, various display technologies such as LCD, flat vision panel, and plasma display pannel (PDP) are thin and light and enable large screen realization.

Among them, the PDP is applied to the surface of the rear substrate by ultraviolet rays generated when a discharge gas is injected between the thin front substrate and the rear substrate on which the plurality of transparent electrodes are formed, and discharged by applying a voltage between the transparent electrodes. The phosphor emits light, and each of the light emitting elements composed of the electrode and the phosphor is formed of cells separated by partition walls, and each of them is driven independently. Not only is it easy to implement a large screen, but also has the advantage of eliminating color bleeding and deterioration of focus, so it has become a focus of attention as a new display means that can overcome the limitation of CRT.

The PDP is classified into a DC PDP driven by a DC voltage and an AC PDP driven by a sine wave AC voltage or a pulse voltage according to the type of driving voltage. In this paper, only the AC PDP will be discussed.

1 illustrates a cell structure of a typical three-electrode surface discharge PDP.

Referring to the drawings, the front substrate 1 and the rear substrate 2 are supported and kept in parallel, and are separated between the cells (spacer) 10 to secure the discharge region (8) and the front substrate ( A row electrode 3 composed of Y and Z electrodes arranged parallel to each other on the surface of 1) and to which an alternating voltage is applied to maintain a discharge, and the front substrate 1 of the back substrate 2. A column electrode 4 which is formed to cross at a right angle on a surface opposite to the row electrode 3 and a predetermined space therebetween and is used for data input for addressing, and the row electrode 3 and First and second dielectric layers 5 and 6 which are formed to cover the column electrodes 4 respectively to limit discharge current during discharge and protect the electrodes, and are formed on the first dielectric layer 5 to Not only protects the first dielectric layer 5 and extends its life, but also the emission efficiency of secondary electrons It increases and reduces the change of discharge characteristics due to oxide contamination of the refractory metal, and is mainly formed of a protective layer (7) formed of MgO thin film, and applied to the second dielectric layer (6) by the ultraviolet rays generated by the discharge A fluorescent layer 9 formed of a phosphor that is excited and generates visible light of one of red (R) green (G) blue (B), and the fluorescent layer 9, the partition 10, and the protective film 7 It is mainly composed of a discharge space (charge space 8) filled with a mixed gas of Ar and Xe in order to increase the ultraviolet emission efficiency to the space for the discharge discharged.

2 is a diagram showing an electrode arrangement of a typical three-electrode surface discharge PDP.

Y electrodes Y ₁ , Y ₂ ,..., Y _{m / 2} , Y _{m / 2 + 1} ,..., Y _m-1 , Y _m , which are row electrodes formed in the horizontal line (H-line) direction, and Z electrodes (Z) ₁ , Z ₂ ,…, Z _{m / 2} , Z _{m / 2 + 1} ,…, Z _m-1 , Z _m , and D electrodes D ₁ , D which are column electrodes formed in the vertical line (V-line) direction. ₂ , D ₃ ,..., D _n-1 , D _n ), a cell 11 formed at a point where the row electrodes and the column electrodes cross each other and arranged in a matrix structure as a whole, and a partition wall made of an insulator ( It is composed of a sealing region 12 which is inserted into a space between the front substrate 1 and the rear substrate 2 and seals the edge portion of the PDP by using an adhesive. The sealing region 12 is maintained in a vacuum state. .

In the AC plasma display panel (AC PDP) having the structure as described above, when a DC voltage is applied between electrodes to discharge, the discharge is extinguished immediately. Write pulse for inputting digital video signal, sustain pulse for maintaining discharge, and erase pulse for stopping discharge of discharged cell It is driven by a matrix addressing method that is independently applied to each of cells.

On the other hand, the plasma display panel (PDP), unlike the CRT that represents the gray scale of the image by adjusting the intensity of the electron beam to scan the fluorescent surface, the method of controlling the number of discharges per unit time due to the difficulty of controlling the intensity of the discharge The gray scale of the image is represented.

In addition, the brightness of the screen is determined by the brightness when each cell is driven to the maximum, and the contrast (contrast), which is a difference in contrast, is determined by the brightness and brightness of the background such as an illumination state, thereby increasing the brightness of the screen. In order to cycle, the number of discharges of a cell must be large within a unit time, and in order to increase contrast, the background must be darkened and the luminance increased.

For example, the actual gray scale and contrast required, for a flat panel display for HDTV, 256 gray scales are required, the resolution must be 1280 × 1024 or higher, and the contrast is 100: 1 under 200 Lux illumination. It should be ideal.

As described above, in the PDP, the brightness of the image, that is, the gray scale, is expressed by adjusting the number of discharges per unit time.

That is, when a time for displaying and maintaining one image on the full screen once is one frame, X subfields are discharged in multiples of 1 to 2 ^X-1 times. field), and each cell discharges only in a corresponding subfield of each subframe and does not discharge in a subfield that is not applicable to each cell. the brightness is determined and implemented by the tone (gray scale) of the 2 ^X level.

As a gray scale implementation method based on the above concept, there are a sub-field method and a sub-frame method. For example, a 256-level gray scale implementation is described first. The subframe method, which is the method to which the invention is applied, will be described in detail.

In the sub-field system, one frame is first divided into eight subfields SF1 to SF8 in order to implement 256 gray levels, and each of the subfields SF1 to SF8 is again divided into a reset period and an address period. It is divided into sustain periods.

The reset period is a period of initializing the screen by writing the entire screen at the same time and then erasing the entire screen again.

In the address period following the reset period, the process of selecting the H-line one by one and selecting only the cells to be ON in the corresponding subfield and selectively discharging the horizontal line H-line Is the time period to perform against

The sustain period is a period in which cells that are turned on in the address period are made to emit light, and the light emission state is maintained, and SF1: SF2: SF3: SF4: SF5: SF6: SF7: for each subfield SF1 to SF8. SF8 = 1: 2: 4: 8: 16: 32: 64: A number of sustain pulses proportional to 128 is applied alternately.

The eight subfields are contiguous in time to complete one frame, and each cell on the screen emits light only in a corresponding subfield of the eight subfields, and not in a subfield that is not applicable. The method of expressing gradation is the subfield method.

However, in the above subfield method, since it takes time to address all horizontal lines (H-lines) of the entire screen at the beginning of each subfield at once, even if each subfield is driven to the maximum, one frame There is an invalid time which does not contribute to light emission during the whole time.

The sub-frame method is to improve the efficiency of the sub-field method as described above.

Similarly in the subframe method, one frame is divided into eight subfields, and the brightness level represented by each subfield is SF1: SF2: SF3: SF4: SF5: SF6: SF7: SF8 = 1: 2: 4: 8: 16: 32: 64: 128, the weighting point is the same as the subfield method, but the subfield method addresses all the lines sequentially at the beginning of each subfield. In order to make up for the disadvantage that invalid time does not contribute to the brightness due to addressing, the subframe method performs the addressing process of the entire screen by distributing a part of the sustain pulse every part of the sustain pulse. It is continuous without interruption.

According to the sub-frame method as described above, since the addressing process of the entire screen is partially distributed, groups of cells in different subfield states exist simultaneously on one screen.

In the sub-frame method, first, the screen is divided into eight in the horizontal line (H-line) direction as shown in FIG. 3 to implement 256 gray levels.

When the total number of H-lines is 510, 256 lines (1 to 256 lines) that sustain the eighth sub-field of 128 brightness are allocated, and the seventh of 64 brightness is assigned. 128 lines (257 to 384) sustaining the subfields, 64 lines (385 to 448 lines) sustaining the sixth subfield of 32 brightness, and sustaining the fifth subfield of 16 brightness. 32 lines (449 to 480 lines), 16 lines (481 to 496 lines) sustaining the 4th subfield of 8 brightness, 8 lines (497 lines) to sustain the 3rd subfield of 4 brightness. 504 lines), four lines sustaining the second subfield of two brightnesses (505 to 508 lines), and two lines sustaining the first subfield of one brightness line (509 to 510 lines), respectively. Assignment as shown in FIG.

After the screen configured as described above is maintained for one sustain period, the partition boundary of the screen moves down one line as shown in FIG.

That is, one line sustaining the eighth subfield of 128 brightness is changed to sustain the first subfield of one brightness, and the 257 lines sustaining the seventh subfield of 64 brightness are the eighth subfield of 128 brightness. Line 385, which sustains the sixth subfield of 32 brightnesses, changes to sustain the seventh subfield of 64 brightnesses, and Line 449 that sustains the fifth subfield of 16 brightnesses, the sixth subfield of 32 brightnesses. Line 481, which is changing to sustain the field, sustaining the fourth subfield of 8 brightness, is changed to sustain the fifth subfield of 16 brightness, and line 497, which is sustaining the third subfield of 4 brightness, is 4 of 8 brightness. The first subfield is changed to sustain, and the line 505 which is sustaining the second subfield of 2 brightness is changed to sustain the third subfield of 4 brightness. And, line 509 were sustained for the first subfield of the first brightness is changed so as to sustain the second subfield of the second brightness.

After the partition boundary of the screen moved as described above is also maintained for one sustain period, the process is repeated by moving down one line again, and after 510 sustain periods, the screen returns to the state shown in FIG. 3 again. At this time, all the lines of the screen sustain the subfield of the next frame.

FIG. 5 illustrates a process in which a subfield sustained by all lines on the screen changes with time through the above-described process.

At this time, it can be seen that the screen division state at time t ₀ is the state shown in FIG. 3.

FIG. 6 is a diagram showing a driving pulse for driving a three-electrode surface discharge PDP by the subframe method as described above.

In the drawing, the sustain pulse applied to the row electrodes Y and Z electrodes maintains the ON state of the cell, and the erase pulse turns off the cell for state change. In this case, a data pulse or a write pulse 0 to 7 selectively applied to the cells to be turned on at the corresponding time point is applied between the Y electrode and the column electrodes D. FIG.

In the driving pulses shown in the figure, a sustain section without an addressing process (SUSTAIN ONLY section) and erase / write (ERASE / WRITE PERIOD) section showing erase / write pulses required for the addressing process for eight lines are shown. ,

The ERASE / WRITE PERIOD section is composed of a section A, which is a sustain section, a section having an erase pulse, and a write section having eight write pulses (0 to 7). It is.

At this time, in the addressing process, one bit value of an 8-bit digital image signal (lowest bit B ₁ to highest bit B ₈ ) corresponding to each cell is applied to the column electrodes. Specifically, a first subfield ( B ₁ during the address period of SF1, B ₂ during the address period of the second subfield SF2,... By applying B ₈ during the address period of the eighth subfield SF8, it is determined whether each cell is turned ON or OFF at that time.

In the conventional subframe method as described above, the addressing process is performed by turning off all the cells of the lines for which the subfields are to be changed first and then turning on the corresponding cells one by one. As described above, as shown in FIG. 6 (256 gray scales), one erase pulse and eight write pulses should be used.

However, since the write pulse has a higher driving voltage and a longer holding time than the erase pulse, the conventional sub-address which mainly uses the write pulse as described above performs the addressing process. The frame method has a limitation in increasing the sustain frequency because all of the write pulses must be included in one sustain period.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and the addressing process is preceded by a writing process of turning on all the cells of all the lines for which the subfield is to be changed, and then erased line by line. A method of driving a 3-electrode surface discharge PDP in which the cells are turned off and the sustain frequency can be increased by using an erase pulse having a lower driving voltage and a shorter holding time than the write pulse. The purpose is to provide.

1 is a view showing a cell structure of a conventional three-electrode surface discharge plasma display panel (hereinafter, referred to as a three-electrode surface discharge PDP);

2 is a diagram showing an electrode arrangement of a three-electrode surface discharge PDP;

FIG. 3 is a diagram for describing screen division in a subframe method for implementing 256 gray scale; FIG.

4 is a diagram for describing an addressing process in a subframe method for implementing 256 gray scales;

FIG. 5 is a diagram illustrating a process of changing a subfield of an entire line on a screen according to time in a subframe method; FIG.

6 is a timing diagram of driving pulses for driving a three-electrode surface discharge PDP according to the related art;

7 is a timing diagram of driving pulses according to the three-electrode surface discharge PDP driving method of the present invention.

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

Y1, Y2,... , Y257,… : Driving pulse applied to Y row electrodes

Z1, Z2,... , Z257,... : Driving pulse applied to Z row electrodes

The driving method of the three-electrode surface discharge plasma display panel (hereinafter referred to as three-electrode surface discharge PDP) according to the present invention for solving the above object,

By dividing one frame into X subfields and adjusting the number of sustain pulses applied in the respective subfields, the level of brightness represented by each subfield is adjusted. With different weights, divide the entire screen into X subscreens along a horizontal line (H-line) and let each of the X subscreens represent different subfields. ) Are driven by a sub-frame method in which an addressing process of changing subfields of some lines is performed every cycle of the sustain pulse so that each of the X subfields is represented once. In the driving method of a three-electrode surface discharge plasma display panel (hereinafter referred to as a three-electrode surface discharge PDP),

In order to increase the frequency of the sustain pulse, an addressing method performed by first applying write pulses to the lines to change the subfields at the same time and then sequentially applying erase pulses line by line Characterized in that.

On the other hand, when trying to implement 256 gray scales, it is appropriate to divide the subfields into eight subfields from SF1 to SF8, and to ensure that each subfield has a brightness level having a different weight. A number of sustain pulses proportional to SF1: SF2: SF3: SF4: SF5: SF6: SF7: SF8 = 1: 2: 4: 8: 16: 32: 64: 128 can be applied per subfield.

In this case, the entire screen is divided into eight sub-screens along a horizontal line (H-line), with 256 lines sustaining the eighth subfield of 128 brightness and sustaining the seventh subfield of 64 brightness. 128 lines, 64 lines sustaining the 6th subfield of 32 brightness, 32 lines sustaining the 5th subfield of 16 brightness, 16 lines sustaining the 4th subfield of 8 brightness, 510 the entire screen by assigning 8 lines to sustain the 3rd subfield of 4 brightness, 4 lines to sustain the 2nd subfield of 2 brightness, and 2 lines to sustain the 1st subfield of 1 brightness. It is preferable to configure the two horizontal lines (H-line).

Due to the operation characteristics of the plasma display panel (PDP), the discharge voltage and time for initially generating wall charges should be higher and longer than the voltage and time applied when the wall charges are erased.

If the cell is to be discharged and turned on during the addressing process, a voltage higher than the threshold required to generate the discharge must be applied between the column electrode and the Y electrode.

The charged particles charged to the insulating film by the discharge are maintained until the erase pulse is applied, and when an erase pulse having a lower amplitude and a narrower pulse width than the write pulse is applied, a small discharge insufficient to generate the charged particles is generated. No discharge occurs even if a sustain pulse is applied.

As described above, since the write pulse has a higher voltage and a larger pulse width than the erase pulse, the conventional sub-frame method of performing the addressing process mainly using the write pulse is addressing. The longer the addressing period, the more constrained the increase in the sustain frequency.

That is, since the C period cannot be reduced in FIG. 6, the sustain frequency is about 15 KHz to 20 KHz, and the driving voltage is very high.

The addressing process of the present invention for solving the problems of the conventional method as described above is performed by first writing all the cells of the lines to be changed and then erasing the cells to be turned off line by line. Lose.

In other words, the present invention first applies a write pulse to eight lines to write data to turn on all the cells of the eight lines, and then sequentially applies erase pulses one by one. In order to reduce the time required for addressing, the erase pulse is mainly used rather than the write pulse, so that the sustain frequency can be increased to increase the brightness of the image. The voltage can also be reduced.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

7 shows a driving waveform of the three-electrode surface discharge PDP according to the present invention as described above.

In the drawings, Y1, Y2,... , Y257,… And Z1, Z2,... , Z257,... Represents driving pulses applied to the Y electrodes and the Z electrodes, respectively, section A is a write section for applying a write pulse to eight lines to change the subfield, and section B is a sustain pulse section and C. The interval is an erasure interval in which erase pulses 0 to 7 are sequentially applied to eight lines for changing the subfield.

As shown in the figure, according to the present invention, since the addressing process of the C section is performed using the erase pulse, the time required for the addressing process is shorter and the driving voltage can be lowered than the conventional method performed using the write pulse. It can be seen.

According to the present invention, unlike the conventional subframe method in which the lines to change the subfields are first erased at the same time and only the cells to be turned on are written and addressed line by line, the subfields are changed. By simultaneously writing the lines to be changed first and then erasing only the cells to be turned off one by one, the addressing process is performed to increase the sustain frequency to increase luminance by about two times or more. There is.

In addition, since the erase pulse having a lower voltage than the write pulse is used, the driving voltage can be reduced to about one third.

Claims (3)

By dividing one frame into X subfields and adjusting the number of sustain pulses applied to each subfield, the level of brightness represented by each subfield is adjusted. With different weights, divide the entire screen into X subscreens along a horizontal line (H-line) and let each of the X subscreens represent different subfields. Grayscale by a sub-frame method having an addressing process of changing the subfields of some lines in each period of the sustain pulse so that each of the X subfields is represented once. In the driving method of a three-electrode surface discharge plasma display panel (hereinafter referred to as a three-electrode surface discharge PDP), In order to increase the frequency of the sustain pulse, the addressing process for the lines to change the subfield is performed by first applying write pulses at the same time and then sequentially applying erase pulses line by line. A method of driving a three-electrode surface discharge PDP. The method of claim 1, In order to implement 256 gray scales, the brightness level represented by each subfield is SF1: SF2: SF3: SF4: SF5: SF6: SF7: SF8 = 1: 2: 4: 8: 16: 32: 64 A method for driving a three-electrode surface discharge PDP, characterized in that the one frame is divided into eight subfields from SF1 to SF8 in proportion to 128. The method of claim 1, The entire screen is composed of 510 horizontal lines (H-line), with 256 lines sustaining the eighth subfield of 128 brightness, 128 lines sustaining the seventh subfield of 64 brightness, and 32 brightness lines. 64 lines sustaining the 6th subfield, 32 lines sustaining the 5th subfield of 16 brightness, 16 lines sustaining the 4th subfield of 8 brightness, and 3rd subfield of 4 brightness. A three-electrode characterized by dividing into eight sub-screens by assigning eight sustain lines, four lines sustaining the second subfield of 2 brightness, and two lines sustaining the first subfield of 1 brightness Method of driving surface discharge PDP.

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