JP5028721B2 - Driving method of plasma display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for driving a plasma display panel.
[0002]
[Prior art]
As shown in the cross-sectional view of FIG. 6, the AC type plasma display panel (hereinafter referred to as “panel”) has two glass front substrates 2 and a glass rear substrate so as to form a discharge space 1 therebetween. 3 are arranged opposite to each other. The discharge space 1 is filled with neon (Ne) and xenon (Xe) that emit ultraviolet rays by discharge. A plurality of discharge electrodes composed of scan electrodes 4 and sustain electrodes 5 are arranged on surface substrate 2, and dielectric layer 6 is formed to cover scan electrodes 4 and sustain electrodes 5. A protective film 7 made of magnesium oxide (MgO) or the like is formed. The scan electrode 4 is composed of a transparent electrode 4a and a metal electrode 4b, and the sustain electrode 5 is composed of a transparent electrode 5a and a metal electrode 5b.
[0003]
On the back substrate 3, a plurality of data electrodes 8 are arranged in parallel to each other in a direction orthogonal to the scan electrodes 4 and the sustain electrodes 5, and a partition wall for isolating each data electrode 8 and forming the discharge space 1. 9 is provided between the data electrodes 8. A phosphor layer 10 is formed to cover the side surfaces of the data electrodes 8 and the barrier ribs 9. A discharge cell is formed at the intersection of scan electrode 4 and sustain electrode 5 with data electrode 8.
[0004]
Next, a method for displaying image data on a conventional panel will be described. The gradation display of an image is performed by dividing one field period into a plurality of subfields having a light emission period weight based on a binary system and combining the subfields to emit light. Each subfield has an initialization period, an address period, and a sustain period.
[0005]
In order to display image data, different signal waveforms are applied to each electrode in the initialization period, the address period, and the sustain period. In the initialization period, for example, a pulse voltage having a positive polarity with respect to the sustain electrode 5 and the data electrode 8 is applied to all the scan electrodes 4 to accumulate wall charges on the protective film 7 and the phosphor layer 10.
[0006]
In the address period, scanning is performed by sequentially applying negative pulses to all the scanning electrodes 4. When there is image data, if a positive data pulse is applied to the data electrode 8 while scanning the scan electrode 4, a discharge occurs between the scan electrode 4 and the data electrode 8, thereby protecting the scan electrode 4. Wall charges are formed on the surface of the film 7.
[0007]
In the subsequent sustain period, sustain pulses having a voltage sufficient to maintain a discharge are alternately applied between scan electrode 4 and sustain electrode 5 for a certain period. FIGS. 7A and 7B show the waveforms of sustain pulses applied to scan electrode 4 and sustain electrode 5, respectively. Sustain pulses have a peak value of V _SO and a direction in which the potential increases (from 0). This is a positive polarity pulse that changes in the direction toward _VSO . Due to the sustain pulse, discharge plasma is generated between the scan electrode 4 and the sustain electrode 5 in the discharge cell having the image data, and the phosphor layer 10 is excited to emit light every time the sustain pulse is applied. In the discharge cell to which no data pulse is applied in the address period, no discharge occurs and excitation light emission of the phosphor layer 10 does not occur. FIG. 7C shows a light emission waveform, and light is emitted every time the sustain pulse rises (the potential changes from 0 to _VSO ).
[0008]
When the panel is driven as described above, a high-luminance image display can be obtained by increasing the peak value (sustain voltage) of the sustain pulse in the sustain period. However, as the sustain voltage increases, the light emission efficiency of the panel Decrease. Therefore, it has been difficult to obtain a high-luminance panel without reducing the luminous efficiency.
[0009]
In order to increase the brightness of the panel, Japanese Patent Application Laid-Open No. 8-314405 discloses that the positive sustain pulses shown in FIGS. 8A and 8B are applied to the scan electrode and the sustain electrode, respectively, during the sustain period. In this case, the peak value V _S1 of the sustain pulse is set to a value that is lower than the discharge start voltage Vf and closest to the discharge start voltage Vf within a range in which no malfunction occurs, and the length of the energization period Ts becomes a wall at the end of the period. It is disclosed that the voltage is set to exceed the discharge start voltage Vf. As a result, as shown in FIG. 8C, light is emitted not only when the sustain pulse rises but also when the sustain pulse falls (potential changes from V _S1 to 0). Light emission due to the falling of the sustain pulse uses discharge (self-discharge) caused by wall voltage due to accumulated charges on the dielectric layer, and light emission due to normal discharge and light emission due to self-discharge occur alternately. ing. By emitting light as shown in FIG. 8C, the number of times of light emission can be doubled the number of times of applying the sustain pulse, and the luminance is improved.
[0010]
[Problems to be solved by the invention]
However, the self-discharge generated by the panel driving method described in Japanese Patent Laid-Open No. 8-314405 is usually generated by a voltage that is the sum of the wall voltage due to the accumulated charge on the dielectric layer and the peak value of the sustain pulse. Unlike the discharge of, this is caused only by the wall voltage due to the accumulated charges on the dielectric layer, and the variation in the wall voltage directly affects the variation in the emission intensity due to the self-discharge. In particular, when the screen is large or the number of discharge cells is large, the emission intensity due to self-discharge varies considerably as the wall voltage varies greatly, making it difficult to display the entire screen cleanly without uneven brightness. there were.
[0011]
The present invention has been made to solve such problems, and an object of the present invention is to provide a plasma display device that achieves high luminance and high luminous efficiency without causing self-discharge.
[0012]
[Means for Solving the Problems]
In order to achieve this object, the plasma display panel driving method according to the present invention includes a plurality of scan electrodes and sustain electrodes arranged on one of two substrates facing each other so as to form a discharge space therebetween. When a plasma display panel is configured by arranging a plurality of data electrodes on the other substrate , and the sustain voltage is increased in the sustain period, the light emission efficiency of the panel first increases to a value higher than the sustain voltage. A negative-polarity pulse having a set peak value , the potential changing in a direction from a positive potential toward 0 and maintaining 0 and then changing in potential from 0 to the positive potential, is applied alternately to the sustain electrode, the scan electrode or the sustain between and to apply the pulse of the scanning electrode and the sustain electrode by the pulse falls Discharge occurs between the poles To the data electrode, discharge due to the rise of the pulse is characterized in that not occur. By this method, light emission by sustain discharge can be obtained without generating self-discharge.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0014]
The driving waveform of the panel in the first embodiment of the present invention is shown in FIG. 1, and the structure of the panel is shown in FIG. In the panel structure, the same parts as those shown in FIG. The panel structure of FIG. 2 is different from that of FIG. 6 in that the scan electrode 11 and the sustain electrode 12 are made of metal electrodes without using transparent electrodes.
[0015]
1A and 1B show voltage waveforms applied to the scan electrode 11 and the sustain electrode 12 in the sustain period, respectively. In the present embodiment, unlike the waveforms shown in FIGS. 7 and 8, the sustain pulse (maintenance of negative polarity) has a peak value of V _S and changes in a direction in which the potential decreases (direction from V _S toward 0). Pulse) is alternately applied to the scan electrode 11 and the sustain electrode 12. FIG. 1C shows a light emission waveform, and a sustain discharge is generated and light is emitted as a sustain pulse is applied. That is, although the sustain pulse falls (potential toward 0 from V _S) is emitting light for each sustain pulse rises (the potential is directed from 0 to V _S) is not sometimes sustain discharge occurs. That is, the above-described self-discharge has not occurred. Therefore, it is possible to prevent the occurrence of luminance unevenness, which has been a problem with conventional panels, and to obtain a display quality superior to that of the conventional panel.
[0016]
Further, when the negative sustain pulse of the present embodiment is applied, not only between the scan electrode 11 and the sustain electrode 12 but also between the scan electrode 11 or the sustain electrode 12 to which the sustain pulse is applied and the data electrode 8. It was confirmed that discharge occurred. This is because, for example, when a negative sustain pulse is applied to the scan electrode 11, the negative wall voltage accumulated on the dielectric layer 6 makes the scan electrode 11 side negative with respect to the data electrode 8 side. Since secondary electrons are generated by colliding with the protective film 7, it is considered that discharge occurs between the scan electrode 11 and the data electrode 8.
[0017]
Next, the results of measuring the panel characteristics when using the drive waveform in this embodiment and when using the conventional drive waveform will be described. For the measurement, the panel having the configuration shown in FIG. 2 is used, the electrode width of the scan electrode 11 and the sustain electrode 12 is 100 μm, the distance dp between the scan electrode 11 and the sustain electrode 12 is 80 μm, and the height of the partition wall 9 Was 120 μm. The panel was sealed with 66.5 kPa of a mixed gas of neon (Ne) and xenon (Xe), and the Xe partial pressure was 5%. In addition, the frequency of the drive waveform of the present embodiment and the conventional drive waveform in the sustain period is 15.3 kHz.
[0018]
FIG. 3A shows a change in luminance with respect to the peak value (sustain voltage) of the sustain pulse, and FIG. 3B shows a change in light emission efficiency. The luminance was measured with a luminance meter, and the luminous efficiency was obtained from the luminance of the panel and the power consumption of the panel. In FIG. 3, the result when the drive waveform according to the present embodiment is used is indicated by a solid line a, and the result when a conventional drive waveform is used is indicated by a solid line b. When the conventional driving waveform is used, the light emission efficiency decreases as the sustain voltage increases, and the light emission efficiency starts to increase when the sustain voltage exceeds 240V. The increase in luminous efficiency when the sustain voltage is increased in this manner is due to the occurrence of self-discharge.
[0019]
On the other hand, when the drive waveform of the present embodiment is used, as shown in FIG. 3B, the light emission efficiency gradually decreases as the sustain voltage increases and becomes a minimum value near 210V. When the sustain voltage exceeds 210V, the light emission efficiency starts to increase, and when the sustain voltage further increases, there is a region where the light emission efficiency decreases. However, the light emission efficiency does not greatly decrease and becomes higher than before. Yes. Further, in the region above the sustain voltage from around 210V, the rate of increase in luminance is higher than in the conventional case, and the luminance is higher than in the conventional case. In the sustain discharge that occurs when using the drive waveform of this embodiment, it has been confirmed that self-discharge has not occurred by measuring the light emission waveform. Occurrence can be prevented, and display quality can be improved as compared with the conventional case.
[0020]
Next, a drive margin representing the ease of driving the panel will be described. When the sustain voltage is lowered, the sustain voltage at which discharge cells that do not emit light without generating a sustain discharge even though there is image data is set to the minimum sustain voltage V _n, and when the sustain voltage is raised, the image is When the maximum sustain voltage V _x is the sustain voltage at which a sustain discharge occurs and the light emitting discharge cell begins to be generated even when there is no data, the drive margin is given by V _x −V _n. Easy to drive with large voltage range. When the panel was driven by a conventional driving method, the minimum sustain voltage V _n was 185 V and the maximum sustain voltage V _x was 250 V. On the other hand, when the panel was driven by the driving method of the present embodiment, the minimum sustain voltage V _n was 185 V and the maximum sustain voltage V _x was 270 V. Therefore, the driving margin of the panel becomes 85V by using the driving method of the present embodiment, which can be 20V larger than the driving margin (65V) in the case of using the conventional driving method, and is easier to drive than the conventional one. It was. In addition, according to the driving waveform of the present embodiment, a higher sustain voltage can be applied as compared to the conventional case, and the rate of increase in luminance is also increased, so that a display with considerably higher luminance than the conventional one can be displayed. It can be carried out.
[0021]
Therefore, in the sustain period, when the sustain voltage is increased, the negative electrode having a peak value set to a value higher than the sustain voltage value (210 V in the present embodiment) when the light emission efficiency of the panel first starts to increase. By applying a sustaining pulse to the scanning electrode 11 and the sustaining electrode 12 to drive the panel, it is possible to obtain a panel with higher luminance and higher light emission efficiency and superior display quality than before.
[0022]
Next, a description will be given of panel characteristics when a panel in which the composition of the sealed gas is changed is driven with the driving waveform of the present embodiment. Measurement was performed by changing the partial pressures of Ne and Xe in a state where the gas sealed in the panel was Ne and Xe and the total pressure was maintained at 66.5 kPa. FIG. 4A and FIG. 4B show graphs of the dependency of luminance and luminous efficiency on the sustain voltage, respectively. In FIG. 4, the result when the Xe partial pressure is 5% is indicated by a solid line a, the result when the Xe partial pressure is 12% is indicated by a solid line b, and the result when the Xe partial pressure is 20% is indicated by a solid line c. Show. In addition, it was confirmed that the above-described self-discharge did not occur in any of the Xe partial pressures in the sustain discharge when the driving method of the present embodiment was used.
[0023]
As can be seen from FIG. 4A, by increasing the Xe partial pressure from 5% to 12% or 20%, the luminance is improved and the rate of increase of the luminance with respect to the sustain voltage is increased. As can be seen from FIG. 4B, when the Xe partial pressure is 12% or 20%, the light emission efficiency takes the minimum value near the minimum sustain voltage, and the sustain voltage value when the light emission efficiency becomes minimum. Exceeding this causes the luminous efficiency to increase, and the luminous efficiency in the high sustain voltage region can be made larger than the luminous efficiency in the vicinity of the minimum sustain voltage. Therefore, when driving a panel with a high Xe partial pressure, when the sustain voltage is increased, the negative polarity having a peak value set to a value higher than the sustain voltage value when the light emission efficiency of the panel first increases. By applying the sustain pulse to the scan electrode 11 and the sustain electrode 12, it is possible to realize a panel with high luminance and high luminous efficiency and excellent display quality.
[0024]
In the above embodiment, the case where the panel includes the scan electrode and the sustain electrode configured only from the metal electrode has been described. However, the panel including the scan electrode and the sustain electrode configured using the transparent electrode as illustrated in FIG. Gives similar results. That is, there is a region where the light emission efficiency increases as the sustain voltage increases, and high luminance and high light emission efficiency can be obtained as compared with the case where the conventional driving waveform is used. In addition, the driving margin is larger than that of the prior art, so that it is easy to drive, and the above-described self-discharge does not occur, so that a panel with excellent display quality in which the occurrence of luminance unevenness is suppressed can be obtained.
[0025]
Therefore, in the sustain period, when the sustain voltage is increased, a negative sustain pulse having a peak value set to a value higher than the sustain voltage value when the light emission efficiency of the panel first starts increasing is shown in FIG. By driving the panel by applying it to the scan electrode 4 and the sustain electrode 5 shown, a panel with higher luminance and higher light emission efficiency and superior display quality can be obtained.
[0026]
Since a large amount of electric power can be input by using a panel having a large electrode width such as a transparent electrode, the panel of FIG. 6 has higher luminance than the panel of FIG. Further, as shown in FIG. 5, instead of using a transparent electrode, the scan electrode 13 and the sustain electrode 14 are each composed of a plurality of divided metal electrodes, and the entire electrode width of the scan electrode 13 and the sustain electrode 14 is equivalent. A wide panel may be used.
[0027]
【Effect of the invention】
As described above, according to the driving method of the plasma display panel of the present invention, in the sustain period, when the sustain voltage is increased, the light emission efficiency of the panel is set to a value higher than the sustain voltage when it first starts to increase. A negative-polarity pulse having a peak value is applied to the scan electrode and the sustain electrode, and a plasma display panel having excellent display quality with high luminance and high luminous efficiency can be obtained.
[Brief description of the drawings]
FIGS. 1A to 1C are waveform diagrams showing sustain voltage waveforms and light emission waveforms in a method for driving a plasma display panel according to an embodiment of the present invention. FIGS. 3 is a cross-sectional view of the plasma display panel. FIG. 3A and FIG. 3B are characteristic diagrams showing the sustain voltage dependence of luminance and luminous efficiency when the plasma display panel of FIG. 2 is driven. FIG. 5B is a characteristic diagram showing the sustain voltage dependence of luminance and luminous efficiency when the plasma display panel of FIG. 2 is driven by changing the Xe partial pressure. FIG. 5 is a plasma display panel according to another embodiment of the present invention. FIGS. 6A and 6B are cross-sectional views of a conventional plasma display panel. FIGS. 7A to 7C are diagrams showing sustain voltage waveforms in the conventional plasma display panel. Waveform diagram showing a slight light emission waveform [8] (a) ~ (c) is a waveform diagram showing voltage waveforms and light emission waveform maintenance in other conventional plasma display panel EXPLANATION OF REFERENCE NUMERALS
DESCRIPTION OF SYMBOLS 1 Discharge space 2 Front substrate 3 Back substrate 4, 11, 13 Scan electrode 5, 12, 14 Sustain electrode 6 Dielectric layer 7 Protective film 8 Data electrode 9 Partition 10 Phosphor layer

Claims (1)

A plasma display panel is configured by arranging a plurality of scan electrodes and sustain electrodes on one of two substrates facing each other so as to form a discharge space therebetween, and arranging a plurality of data electrodes on the other substrate. In the sustain period, when the sustain voltage is increased, the panel has a peak value set to a value higher than the sustain voltage when the light emission efficiency of the panel first starts increasing, and the potential in the direction from the positive potential toward zero said scanning but a negative pulse potential changes in the direction toward the positive potential from 0 after maintaining the 0 changes, and alternately applied to the sustain electrode and the scan electrode by the pulse falls A discharge occurs between the electrode and the sustain electrode and between the scan electrode or the sustain electrode to which the pulse is applied and the data electrode, and the discharge occurs at the rising edge of the pulse. The driving method of a plasma display panel, characterized in that does not occur.

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