JP3394003B2 - Driving method of plasma display panel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a plasma display panel for displaying a high-quality image on the plasma display panel. 2. Description of the Related Art At present, a plasma display panel is attracting attention as a flat display device, and a plasma display driving method for displaying an image with high image quality is being developed. FIG. 9 shows the connection between the plasma display panel and the data-side drive unit, the scan-side drive unit, and the sustain-side drive unit in the case of the dual scan drive system in which data electrodes are divided and arranged on the upper part 38 and the lower part 39 of the plasma display panel. FIG. An upper data driver 34 is connected to a plurality of data electrodes 30 arranged on the upper portion of the plasma display panel, and the data electrode 31 is connected to a lower portion of the panel.
The lower data-side drive unit 35 is connected to a plurality of data-side electrodes 31 arranged in a row, and n lines (n is an even number) crossing vertically
The scan-side drive unit 36 is connected to the scan-side electrode 32, and the sustain-side drive unit 37 is connected to the n sustain-side electrodes 33 arranged in parallel with the scan-side electrode 32. FIG. 8 is a schematic diagram of a cell structure of an AC discharge type plasma display panel. As shown in FIG.
The scan side electrode 32 and the sustain side electrode 3
3, a dielectric 41 and a protective film 42 are arranged,
On the surface of 4, a data electrode 31, a dielectric 45, a cell partition 43 and a phosphor 46 are arranged. Further, a gas 47 for emitting and discharging light is sealed in the space in the cell. [0005] In a plasma display panel, a method of expressing gradation by dividing an image of one frame into a plurality of subfields (hereinafter referred to as "SF") is used. In the AC discharge type, generally, 1S. F. Is further divided into four periods. The four periods will be described with reference to FIG. [0006] FIG. F. 9 is a driving waveform of a conventional AC discharge type plasma display in FIG. In the setup period 1, wall charges are uniformly accumulated in all cells in the plasma display panel in order to easily generate discharge. In the address period 2, write discharge of the cell to be lit is performed. In the sustain period 3, the cells written in the address period 2 are turned on, and the lighting is maintained. In the erase period 4, lighting of the cell is stopped by erasing the wall charges. In the figure, 5 is the last scan pulse, 6 is the first sustain pulse, 7 is the sustain-side electrode applied voltage waveform, 8 is the first and nth n-th (n is an even number) scan lines from the top of the plasma display panel.
/ 2 + 1 scan-side electrode applied voltage waveform, 9 is the second and n / 2 + 2nd scan-side electrode applied voltage waveforms from the top of the same panel, 10 is the n / 2th and n-th scan-side electrode applied from the top of the same panel 5 shows a voltage waveform. The four periods will be described in detail with reference to FIG. Here, the lower cell of the plasma display panel will be described as an example, but the same can be said of the upper cell of the panel. FIG. 10 is a cell cross-sectional view for explaining discharge in the cell. In the setup period 1, a higher voltage is applied to the scan-side electrode 32 than the data-side electrode 31 and the sustain-side electrode 33 and the gas 4 in the cell is applied.
7 is discharged (a in the figure). The generated charges are accumulated on the wall surface of the cell so as to cancel the potential difference between the data-side electrode 31, the scan-side electrode 32, and the sustain-side electrode 33. The charges are accumulated as wall charges, and positive charges are accumulated as wall charges on the phosphor layer surface 50 near the data-side electrode 31 and the protective film surface 52 near the sustain-side electrode 33. Due to the wall charges, a wall potential V1 is generated between the scan side electrode and the data side electrode, and a wall potential V2 is generated between the scan side electrode and the sustain side electrode (b in the figure). In the address period 2, when the cell is turned on, a voltage lower than that of the data side electrode 31 and the sustain side electrode 33 is applied to the scan side electrode 32, that is, the wall potential is applied between the scan side electrode and the data electrode. V
1 and a voltage is applied between the scan-side electrode and the sustain-side electrode in the same direction as the wall potential V2, thereby generating a write discharge (c in the figure). Thereby, the phosphor layer surface 50 and the protective layer surface 52
, Negative charges are accumulated, and positive charges are accumulated as wall charges on the protective layer surface 51 near the scan-side electrode 32 (d in the figure). As a result, a wall potential V3 is generated between the sustain electrode and the scan-side electrode (e in the figure). In the sustain period 3, the scan side electrode 32
, A sustain discharge is generated by applying a voltage higher than that of the sustain-side electrode 33, that is, by applying a voltage between the sustain-side electrode and the scan-side electrode in the same direction as the wall potential V3 (f and g in FIG. ). Thereby, cell lighting can be started. By applying a pulse so that the polarity of the sustain-side electrode and the scan-side electrode is switched alternately, pulse emission can be performed intermittently. [0010] By the way, when a plasma display panel having a large cell pitch is turned on, this is not a problem. However, when a high-definition plasma display panel having a small cell pitch is turned on, the upper and lower portions of the panel are turned on. And a lighting failure occurs in the cell near the center. In particular, lighting failure near the center of the panel is a serious problem for a display device. Hereinafter, the problem will be described. The lighting failure depends on the cell size of the plasma display panel, the driving conditions, and the like, and is largely as follows.
Can be classified into one. In the first lighting failure, a lighting failure occurs in a band shape below the panel upper portion 38 and the panel lower portion 39 in FIG. 9 (hereinafter, referred to as a “band lighting failure”). When the present inventors investigated this cause,
Excessive discharge occurs during the initial pulse application of the sustain period, causing abnormalities in wall charges and sustaining discharge does not continue.Further, excessive discharging is a state in which the gas in the cell is in an excited state by writing discharge. However, it was found that this was caused by applying a sustain pulse. The second lighting failure is caused by the upper panel 38 in FIG.
In addition, a bright line is generated below the panel lower portion 39 (hereinafter, referred to as “over-discharge lighting failure”). This occurs because the wall charges of the lowermost cells of the panel upper part 38 and the panel lower part 39 are accumulated more than the wall charges of the upper cells of the panel upper part 38 and the panel lower part 39. This will be described in detail with reference to FIG. FIG. 11 is a schematic view of a panel at the center of the plasma display panel. Upper data side electrode 30, lower data side electrode 31, scan side electrode 3
2, the sustain-side electrode 33 and the cell partition 43 are viewed from the panel surface plate. Write discharge is performed sequentially in the address direction in the drawing, so that a write discharge is generated in a certain cell, and then a write is performed in a cell below the same cell, so that part of the charge at the time of the write discharge sequentially moves to the lower cell. I do. However, in the cell on the last scan line of the upper panel in the figure, after writing discharge, writing is not performed in a cell below the same cell, so that surplus charges after the writing discharge occurs are accumulated as wall charges. As a result, the wall potential V3 in FIG. 10 increases, and a sustain discharge is generated by applying a voltage lower than that of the other cells between the sustain electrode and the scan electrode, and appears as a bright line on a display image. The third lighting failure is the upper panel 38 in FIG.
In the upper cell of the lower panel 39, the probability of writing failure is higher than in other cells, and this is a lighting failure in which a lighting failure occurs near the center of the panel (hereinafter, referred to as a “writing failure lighting failure”). In the upper cells of the panel upper part 38 and the panel lower part 39, a discharge is generated at the very beginning of the address period. Therefore, the amount of excited gas is small, so that the writing discharge is hard to occur, and the probability of writing failure becomes higher than other cells. That is the cause. SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned conventional problems, and displays a high-quality image by adjusting the amount of charge in the gas immediately before the sustain discharge and the intensity of the write discharge. It is an object of the present invention to provide a driving method of a plasma display panel for driving the plasma display panel. [0015] The following method is used to solve the above-mentioned problems. In order to suppress the band-shaped lighting failure, which is the first lighting failure, a period is provided between the final scan pulse and the first sustain pulse for eliminating charges in the gas in the cell. In order to suppress the second discharge failure, that is, the over-discharge lighting failure, the voltage applied to the sustain electrode is reduced when the final scan pulse is applied as compared to when another scan pulse is applied. Alternatively, the pulse width of the final scan pulse is reduced when the final scan pulse is applied as compared with when another scan pulse is applied. In order to suppress a third lighting failure, that is, a writing failure lighting failure, the voltage applied to the sustain electrode is increased at the time of writing a cell in the first scan line at the top of the panel and at the bottom of the panel as compared to when writing other cells. By using these methods, the discharge in the cell is performed stably, and a high quality image can be displayed. Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a method of driving a plasma display panel by a dual scan method according to Embodiment 1 of the present invention. 7, 1 is a setup period, 2 is an address period, 3 is a sustain period, 4 is an erase period, 5 is a final scan pulse, 6 is a first sustain pulse, 7 is a sustain-side electrode applied voltage waveform, as in FIG. , 8 are the first and n from the top of the plasma display panel having n (n is an even number) scan lines.
/ 2 + 1 scan-side electrode applied voltage waveform, 9 is the second and n / 2 + 2nd scan-side electrode applied voltage waveforms from the top of the same panel, 10 is the n / 2th and n-th scan-side electrode applied from the top of the same panel Represents the voltage waveform, 2
0 represents the time from the last scan pulse to the first sustain pulse. In FIG. 1, the upper part of the voltage waveform shows a high potential and the lower part of the figure shows a low potential. The cell in which wall charges are actually formed in the address period is a cell in which a data-side electrode to which a write signal pulse is applied and a scan-side electrode to which a scan pulse is applied intersect. Here, the cause of the first lighting failure will be described. When the charge generated by the write discharge is in a state where the gas sealed in the cell is in an excited state, the first pulse in the sustain period is the first pulse. When the sustain pulse 6 is applied, an excessive sustain discharge occurs and wall charges are excessively accumulated. Thereafter, the discharge is generated by discharging the wall charges at the falling of the first sustain pulse, and the discharge when the next sustain pulse is applied is weakened, so that the sustain discharge cannot be sustained. Therefore, a band-shaped lighting failure occurs. Therefore, in the present embodiment, in order to avoid the influence of the write discharge, which is the cause of the first lighting failure, the final scan pulse 5 is applied, and then the excited state of the gas generated by the write discharge is increased. Becomes stable after a lapse of time, that is, after a lapse of time 20, the first
The sustain pulse 6 is applied, thereby suppressing an excessive sustain discharge. Here, time 20 corresponds to FIG.
, The time from the trailing edge 5a of the final scan pulse 5 to the leading edge 6a of the first sustain pulse 6 is indicated. The time 20 may be longer than at least as long as the gas changes from an excited state to a stable state. However, if the time is too long, the sustain period 3 is shortened, and the voltage is applied. Since the number of sustain pulses must be reduced and the brightness decreases,
It is desirable that the sustain period is a time period such that the luminance is not reduced by being compressed. The time required for the gas in the cell to transition from the excited state to the stable state depends on the type and composition of the gas, but the time 20 from the last scan pulse 5 to the first sustain pulse 6 should be reduced from 20 μs to 80 μs. The inventors experimentally confirmed that the band-shaped lighting failure can be prevented by the method. The period during which the gas transitions from the excited state to the stable state can be measured as follows. The measurement is performed by applying a pulse as shown in FIG. 2 to each of the scan side electrode, the sustain side electrode, and the data side electrode. That is, by applying the pulse P1 to the scan-sustain side electrode alternately for the period of T1, the gas in the cell is discharged and the panel is lit. Thereafter, after a period of T2, a pulse (erase pulse) P2 having a smaller time width than the pulse P1 is applied to the data side electrode. At that time, discharge occurs, but T2 is gradually increased, and T2 at which no discharge occurs is measured. This is based on the fact that a discharge is generated by the erase pulse P2 when the gas in the cell is in an excited state, but no discharge is generated when the gas is in a stable state. The period T2 determined in this way is a period during which the gas shifts from the excited state to the stable state. Incidentally, conventionally, it is considered that a period from application of the final scan pulse 5 to application of the first sustain pulse was about 10 μs. Embodiments 2 and 3 described below are driving methods of a plasma display panel invented to solve the above-described second lighting failure. That is, this is an example of a method of eliminating an overdischarge lighting failure by preventing excess charges from accumulating in the last line of the upper panel and the lower panel. An overdischarge lighting failure, which is a second lighting failure, is as follows:
The cells in the n / 2-th and n-th scan lines are generated because more wall charges are accumulated than in the other scan lines.
This is because writing is started from the first and n / 2 + 1th scanning lines, and writing is sequentially performed up to the n / 2th and nth scanning lines, so that the n / 2th and nth writing lines to be written last are written. The scan line is due to the accumulation of surplus charges after the writing discharge as wall charges. In order to prevent the surplus electric charges from being accumulated in the last lines at the upper part of the panel and at the lower part of the panel, concretely, the following second and third embodiments are used. (Embodiment 2) FIG. 3 shows a method of driving a plasma display panel according to Embodiment 2 of the present invention. In FIG. 3, the same numbers as those in FIG. 1 represent the same elements. In FIG. 3, reference numeral 21 indicates that the voltage applied to the sustain electrode is reduced when the final scan pulse is applied to the scan-side electrode. As described above, n is the last to be written.
On the / 2nd and n-th scanning lines, surplus charges after the writing discharge are accumulated as wall charges. Therefore, when the voltage is applied under the same conditions as the other scan lines, the sustain discharge starts at a lower voltage than the other cells in the sustain period. Therefore,
In this embodiment, the voltage applied between the sustain electrode and the scan electrode is reduced in the last scan line as indicated by 21 in FIG. 3 in order to suppress the overdischarge lighting failure as the second lighting failure. . This makes it possible to adjust the amount of wall charge by reducing the amount of charge accumulated on the cell wall so as to cancel the potential difference between the scan side electrode and the sustain side electrode after the write discharge. And
The wall charge of the cell at the end of the address period can be made uniform, and the image can be displayed with high quality. (Embodiment 3) FIG. 4 shows a method of driving a plasma display panel according to Embodiment 3 of the present invention. In FIG.
Represents similar elements. In FIG. 4, reference numeral 22 denotes the width of the final scanning pulse. In order to suppress the overdischarge lighting failure, which is the second lighting failure, the final scan pulse width 22 in FIG. 4 is made shorter than the other scan pulses, so that the charges in the gas move to the cell wall and are accumulated. The amount of wall charge is adjusted by suppressing the occurrence of the charge. Thereby, the wall charges of the cell at the end of the address period can be made uniform, and the image can be displayed with high quality. (Embodiment 4) FIG. 5 shows a method of driving a plasma display panel according to Embodiment 4 of the present invention. In FIG. 5, the same reference numerals as those in FIG.
Represents similar elements. In FIG. 5, reference numeral 23 indicates that the voltage applied to the sustain electrode is increased when the first scan pulse is applied to the scan electrode. The third lighting failure, which is a writing failure lighting failure, is caused by the fact that the cells in the first and (n / 2 + 1) th scanning lines are not in the excited state of the gas, and the probability that a writing discharge will occur is caused by other cells. It is lower than. A high voltage is applied between the sustain electrode and the scan electrode as shown at 23 in FIG. 4 to increase the voltage applied to the gas in the cell, as indicated by 23 in FIG. Thereby, the discharge of the same gas is promoted, and the probability of occurrence of the write discharge can be increased. Therefore, writing defects are reduced, and unlit cells in the upper and central portions of the plasma display panel are reduced, so that high-quality images can be displayed. Here, an example of a circuit for controlling each electrode driving section so as to have the above-described voltage waveform will be described. FIG. 6 is a diagram showing the configuration of the circuit. To adjust the waveform,
This is performed by the timing control unit 60. The timing controller 60 includes a clock generator 61, an address period controller 6,
2 and a sustain period control unit 63. The clock generation unit 61 is a circuit that generates a clock pulse serving as a timing reference when controlling the voltage waveform applied to each electrode based on the horizontal and vertical synchronization signals separated from the video signal. The control unit 62
The sustain pulse control unit 63 controls the waveform and application timing of the scan pulse in the address period, and controls the waveform and application timing of the sustain pulse in the sustain period. The address period control section 62 includes a counter section 62a and a control signal generation section 62b, and the sustain period control section 63 includes a counter section 63a and a control signal generation section 63b. Counter 62
a and 63a count clock pulses generated by the clock generator 61. Note that the counters 62a, 6
3a is 1S. It is reset when F ends. The control signal generator 62b includes a counter 6
Based on the count value of 2a and the subfield information read from the frame memory 65, a timing signal for generating a write signal pulse to be applied to the data electrode is generated and transmitted to the upper data driver 34 and the lower data driver 35. Output. At the same time as the generation of the control signal, it instructs the scan driver 36 and the sustain driver 37 to apply a pulse of a predetermined voltage. Here, the subfield information is information indicating which subfield is to be turned on or off in order to display a corresponding gradation value in each pixel. Note that the input video signal is converted into subfield information generated for each pixel by the A / D converter 64 and the subfield division control unit 65, and then temporarily stored in the frame memory 66, where the control signal generation unit 62b
Is read. The control signal generator 63b includes a counter 6
In response to the count value 3a, a control signal for controlling the potential of the voltage applied to the scan-side electrode and the potential and timing of the scan pulse applied to the sustain-side electrode is generated, and the scan-side drive unit 36 and the sustain-side drive unit 37. More specifically, first, the clock generator 6
A clock pulse is generated at 1 and counted by the counter section 62a. When the count value reaches one line (row direction), the subfield information is read from the frame memory 66 and written to one line. At the same time, the counters 62a, 62
The clock pulses are counted in 3a, and the control units 62 and 63 generate control signals corresponding to the count value. That is, in the case of the first embodiment, the sustain period control unit 6
3 is a control signal generator 6 that applies a sustain pulse to the scan / sustain side electrode when the count value of the counter 63a reaches a predetermined value K1.
The control signal generated in 3b is output to each electrode drive unit to issue an instruction to that effect. Here, the count value K1 is equal to the first
A value that takes into account the period during which the gas transitions to a stable state from the point in time when writing to each line is completed, that is, from the point in time when the last scan pulse is applied, so that the strip-shaped lighting failure, which is the lighting failure, can be resolved. Is set to Next, in the case of the second embodiment, if the count value of the counter unit 62a reaches a predetermined value K2, the address period control unit 62 performs a write operation on the next line. Outputs the signal generated by the control signal generator 62b to the sustain electrode driver so as to lower the potential applied to the sustain electrode, and issues an instruction to that effect. Here, the count value K2 is determined by the (final line-
1) The value is set to a value at which writing to the first line is completed. Therefore, the wall charge formed by writing to the last line is prevented from becoming excessive, and the second discharge failure, that is, the over discharge discharge failure, can be solved. In the case of the third embodiment, the count value of the counter 62a is set to a predetermined value K2.
Then, when writing to the next line, the address period control unit 62 issues an instruction to the sustain-side electrode driving unit so as to reduce the width of the pulse applied to the sustain-side electrode. This avoids excessive wall charges formed by writing to the last line, so that the second
It is possible to eliminate the over-discharge lighting failure, which is the lighting failure of. Further, in the case of the fourth embodiment, when the count value of the counter section 62a reaches a predetermined value K3, the address period control section 62 temporarily changes the potential applied to the scan side electrode. The control signal generated by the control signal generation unit 62b is output to the scan-side electrode drive unit to instruct so. Here, the count value K3 is set to a value at the time when writing starts on the first line of each of the upper panel and the lower panel in the two-split screen. Therefore, writing defects at the time of writing to the first line are reduced. Although the present invention has described the lighting failure at the upper end, lower end and near the center of the plasma display panel when the data side electrodes are vertically divided,
Even in the case of using the single scan method in which the data-side electrodes are driven without being divided, the same lighting failure occurs at the upper and lower ends of the panel. It goes without saying that the occurrence of lighting failure can be suppressed by using the above method. As described above, according to the driving method of the plasma display panel of the present invention, the following effects can be obtained. That is, by providing a period for extinguishing the electric charge in the gas in the cell between the final scan pulse and the first sustain pulse, the suspension of the sustain discharge can be suppressed, and the strip-shaped lighting failure can be prevented. In addition, by reducing the voltage applied to the sustain electrode at the time of applying the final scan pulse compared with the time of applying the other scan pulse, or reducing the pulse width of the final scan pulse at the time of applying the final scan pulse as compared with the time of applying the other scan pulse, after the writing discharge. Cell uniform in the panel, and overdischarge lighting failure can be suppressed. Further, the voltage of the sustain electrode applied to the cells in the uppermost scan line (the first line in each of the upper and lower parts of the screen divided into two in the case of the dual scan method) is lower than in the other cells. By increasing the number, it is possible to promote write discharge and prevent write failure lighting failure. As described above, since the lighting failure can be eliminated,
High-quality images can be realized on a high-definition panel with a fine cell pitch. In particular, there is a remarkable effect in that a high-quality image is displayed on a dual scan type plasma display panel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a driving method of a plasma display panel according to Embodiment 1 of the present invention. FIG. 2 is a diagram illustrating a method for measuring a period during which a gas transitions from an excited state to a stable state. FIG. 3 is a diagram showing a method for driving a plasma display panel according to Embodiment 2 of the present invention. FIG. 4 is a diagram showing a driving method of a plasma display panel according to Embodiment 3 of the present invention. FIG. 5 is a diagram showing a driving method of a plasma display panel according to Embodiment 4 of the present invention. FIG. 6 is a diagram showing a configuration of a timing control unit according to the embodiment of the present invention. FIG. 7 is a diagram illustrating an example of a conventional driving method of a plasma display panel. FIG. 8 is a diagram showing an example of the structure of a plasma display panel. FIG. 9 is a diagram illustrating connections of a plasma display panel, a data-side drive unit, a scan-side drive unit, and a sustain-side drive unit according to the related art and the embodiment. FIG. 10 is a diagram for explaining a discharge in a cell. FIG. 11 is a diagram for explaining write discharge of a cell at the center of the plasma display panel. [Description of Signs] 1 Setup period 2 Address period 3 Sustain period 4 Erase period 5 Final scan pulse 6 First sustain pulse 7 Sustain side electrode applied voltage waveform 8 First and n / 2th scan side electrode applied voltage waveforms 9 2 The first and n / 2 + 1-th scan-side electrode applied voltage waveforms 10 The n / 2-1-th and n-th scan-side electrode applied voltage waveforms 20 Time from the last scan pulse to the first sustain pulse 60 Timing control unit 61 Clock generation unit 62 address period control unit 62a counter unit 62b control signal generation unit 63 sustain period control unit 63a counter unit 63b control signal generation unit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Kawahara 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-10-83159 (JP, A) JP-A-2000-113822 (JP, A) JP-A-2000-214822 (JP, A) JP-A-11-327505 (JP, A) JP-A-2000-66636 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G09G 3/28 G09G 3/20 622 G09G 3/20 624 G09G 3/20 642

Claims (1)

(57) Claims 1. A first region of a plasma display panel
A plurality of first column electrodes and a second region
A plurality of second column electrodes arranged, a plurality of first row electrodes arranged to intersect with the column electrodes, and a plurality of first row electrodes arranged in parallel with the first row electrodes. a plasma display panel having a second row electrode, the turning on or off of the cell by applying a write pulse to the column electrodes in accordance with image data with sequentially applies a scan pulse to said plurality of first row electrodes An image is displayed on a plasma display panel by repeating a selected address period and a sustain period for alternately applying a sustain pulse to the first row electrode and the second row electrode to maintain lighting of a cell, thereby displaying a dual scan. By formula
A driving method for driving a plasma display panel , wherein the first row electrode and the second row electrode are arranged at a beginning of a sustain period from a trailing edge of a scan pulse applied to a first row electrode at the end of the address period. 20 μs before the leading edge of the first sustain pulse applied to the row electrode
A method for driving a plasma display panel, comprising a time width of ec to 80 μsec .