JP2011028188A - Method of resetting long-gap pdp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein when an interval between display discharge electrodes which is commonly known as scanning electrode and sustaining electrode of an AC-type PDP which are parallel to each other and form a pair is formed as pixels having a comparatively long gap, for example, 200 microns, it is difficult to perform charging which is effective and does not cause contrast degradation, that is, the so-called reset discharging, due to the high discharge voltage due to the long gap. <P>SOLUTION: In this PDP, reset discharging is performed not between the scanning electrode and the sustaining electrode, but between the scanning electrode and the address electrode, and the sustaining electrode and the address electrode independently with a continuous timing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a plasma display panel so-called PDP driving method.

A PDP is a display device using gas discharge, and is composed of discharge electrodes arranged in an XY shape and a dielectric layer covering the discharge electrodes. As a basic structure, as shown in FIG. 5, the back side substrate 1 has a plurality of electrodes 8 called address electrodes extending in the vertical direction of the screen. There are a plurality of electrodes 6 called scan electrodes extending in the lateral direction perpendicular to 8 and charges are accumulated on the dielectric layer by discharging according to the image signal using a plurality of points where these electrodes intersect as pixels. To do. This is called address discharge.

In a general PDP, it is necessary to form a phosphor on the back side substrate on which the address electrode 8 is formed. Therefore, although not shown in FIG. It is desirable to separate the address discharge electrodes and the display discharge electrodes in order to avoid damage to the phosphors formed by the display discharge. Therefore, in a general PDP, a third electrode 7 called a sustain electrode is arranged in parallel with the scan electrode 6 on the front side, and the display discharge is displayed in accordance with the image based on the charges formed by the address discharge. Discharging is performed between the scan electrode 6 and the sustain electrode 7. This display discharge is sometimes referred to as a memory discharge because a discharge called a sustain pulse is applied between the electrodes, and charges having different polarities are alternately formed for each pulse, so that the discharge can be continuously maintained. In general, the scan electrode 6 may be referred to as an X electrode, the sustain electrode 7 as a Y electrode, and the address electrode as an A electrode.

By the way, in the above-described discharge mode, in order to perform display discharge separately for each pixel, that is, to perform address discharge for distinguishing lighting non-lighting for each pixel, before performing address discharge, each pixel is once displayed on the previous screen. A so-called reset discharge is required after canceling the formed charge. This reset discharge is an extremely important action in the PDP that performs display by forming charges individually as described above, and it needs to be completely performed regardless of whether it is the three-electrode type or the four-electrode type.

FIG. 4 shows a voltage waveform of a pulse applied to each electrode for a general reset discharge. FIG. 4A shows an example of a driving waveform used in an actual PDP, but the simplified waveform shown in FIG. 4B is used to explain the basic operation of the reset pulse. . FIG. 5 is a schematic cross-sectional view showing the electrode configuration of the PDP. As described above, the electrode configuration of the PDP is the Y electrode, ie, the sustain electrode 7, the X electrode, ie, the scan electrode 6 disposed on the same front side substrate 5 in parallel therewith, and the A electrode, ie, address, on the opposite back side substrate 1. The electrode 8 is composed of these three electrodes. In addition, a dielectric layer that accumulates electric charges for operating by superimposing a voltage on each electrode, which is a basic element in PDP operation, covers each electrode as a front-side dielectric layer 4 and a back-side dielectric layer 3. The PDP composed of these three different electrodes is called a three-electrode type PDP. However, a method of using a four-electrode type has been proposed in order to perform the address discharge and the sustain discharge with a completely separated electrode group. In both the three-electrode type and the four-electrode type, the reset discharge needs to be uniformly performed on all the pixels regardless of the electric charge accumulated in each electrode in the previous screen.

The reset pulse is first applied to the Y electrode, ie, the sustain electrode 7, and reset discharge is performed between the X electrode, ie, the scan electrode 6 arranged in parallel. The general PDP structure shown in FIG. 5 is called a so-called short gap structure, and the distance between the tips of the X and Y electrodes is about 80 microns, and the distance between the Y electrode and the A electrode is about 100 microns. When the conventional reset pulse shown in FIG. 4 is applied here, the discharge occurs between the XY interelectrode discharge 21 and the XA interelectrode discharge 20 almost simultaneously. In this case, the reset pulse is set to a sufficiently high voltage because it is necessary to cause discharge in all the pixels regardless of the charges accumulated in the back side dielectric layer 3 and the front side dielectric layer 4 on the surface of each electrode, so-called wall charges. The In FIG. 4, the voltage due to the wall charges is represented by a dotted line as the wall voltage 11. Also, in the normal PDP electrode structure, there is no significant difference in the discharge start voltage between XY and AY, and the discharge occurs almost simultaneously, but the main discharge is XY because there is a phosphor on the dielectric layer on the back side. Occurs between electrodes. Note that the reset waveform shown in Fig. 4 (a) slopes the rise and fall of the pulse for the purpose of weakening the light emission during reset discharge and preventing the decrease in contrast, and for surely forming the wall charge once formed on the electrode. The so-called ramp waveform is generally used, but since it is irrelevant to the present invention, the following description including the present invention will be made with a basic square type pulse as shown in FIG. To do.

In the reset operation by the pulse of FIG. 4, a relatively large pulse is first applied to the Y electrode 7 so that discharge is uniformly generated in all pixels. Since the wall charges due to the display before resetting are accumulated on the surfaces of the X, Y, and A electrodes, respectively, the voltage is sufficiently high so that the discharge is performed regardless of the presence of the charges or the polarity. Applied. Since there is almost no difference in the distance between the XY electrodes and between the AY electrodes, a positive high voltage applied to the Y electrode 7 causes a discharge between XY and AY almost simultaneously, and negative wall charges, X Positive charges are accumulated in the electrode 6 and the A electrode 8. In general, there is a phosphor on the surface of the A electrode, and since the dielectric constant of the A electrode 8 side, that is, the back side dielectric layer 3 is smaller than that of the front side dielectric layer 4, the wall charges formed on the A electrode are Smaller than the X electrode side. When a large pulse is applied to the Y electrode at an early rise, a large discharge current flows instantaneously, so that strong light emission is observed and this causes a decrease in display contrast. Therefore, the rise is generally raised slowly.

Next, at the timing of the fall of the pulse applied to the Y electrode 7 first, the Y electrode 7 is set to the negative side and the X electrode 6 side is set to make the wall charges formed in each pixel more uniform by the first discharge. Applies a positive pulse and discharges in the opposite polarity to the first discharge. As a result, positive wall charges are formed on the Y electrode side and negative wall charges are formed on the X side at the end of the reset operation. Although some positive charge remains in the A electrode 8, it is less than the charge amount of the X and Y electrodes for the reason described above. Thus, the normal PDP reset discharge is performed between the Y electrode 7 and the X electrode 6 on the front side.

JP2002-22950 JP-A-2005-4213 JP2008-134372

In recent years, as a measure to reduce the power consumption of PDP, in order to improve the light emission efficiency of the discharge cell, from the conventional method of emitting phosphors using ultraviolet rays from negative glow, to the method of using a positive column. Conversion is planned. However, in order to generate a positive column in each pixel, the distance between the discharge electrodes, that is, the Y electrode that is the sustain electrode 7 and the X electrode that is the scan electrode 6 must be longer than a certain extent. For example, as described above, in a normal PDP, for example, a PDP in which a mixed gas of Ne and Xe is sealed at about 400 Torr, the tip distance between the parallel Y electrode and the X electrode is about 80 microns. Needs to have a gap of about 200 microns to 300 microns or more.

When driving such a positive column type PDP having a long distance between the discharge electrodes, the above-described reset discharge becomes a serious problem. That is, in the case of a normal negative glow type PDP, since the distance between the Y electrode and the X electrode is relatively short, about 80 microns, the reset discharge sufficiently occurs between the XY electrodes even with the reset pulse as described above. However, in the case of a positive column type PDP, the distance between the Y electrode and the X electrode becomes large, and in order to cause a reset discharge between these electrodes, the reset voltage must be further increased. This is not only a burden on the driving circuit, but also a big problem for realizing a positive column type PDP because a large light emission due to a strong reset discharge causes a decrease in image contrast.

Therefore, in the present invention, the reset discharge is not performed by the Y electrode and the X electrode, but separate discharge is performed by the Y electrode and the A electrode, and the X electrode and the A electrode at successive timings, and finally the Y electrode and the X electrode. A method for driving a PDP that uniformly forms wall charges with different polarities on a screen is provided. In the conventional reset method, the inter-XA discharge 20 and the inter-XY discharge 21 occur, but no discharge between YA occurs.

According to the present invention, it is possible to improve the display quality by reducing the reset voltage of the positive column type PDP and preventing the image contrast from being lowered by the reset discharge.

[First Embodiment]
The reset operation of the present invention will be described below with reference to FIG. 2 which is a reset pulse waveform and FIG. 1 which is a schematic cross-sectional view of a pixel for explaining the operation in a timely manner. First, the cross-sectional view of FIG. 1 schematically shows the electrode configuration of a positive column type PDP. Basically, the configuration is the same as that of a normal PDP, but the gap between the X electrode and the Y electrode is wider than that of the normal PDP shown in FIG. 4, for example. For example, the distance between AX and AY is about 100 microns, which is the same as usual, whereas the distance between XY is about 200 to 300 microns, which is about twice or more.

P1 and P2 shown in FIG. 1 represent the timing of the discharge 20 between AX and the discharge 22 between AY, respectively. P1 and P2 are performed not at the same time but at successive different timings. The pulse waveform that accomplishes this is shown in FIG. In FIG. 3, the same operation as described above is realized at different pulse timings.

An embodiment of the present invention will be described with reference to FIG. First, the discharge 20 of P1 is performed between the A electrode and the X electrode. For this purpose, a pulse having a voltage sufficient to discharge between the A electrode 8 and the X electrode is applied. At this time, the pulse of the A electrode and the pulse of the conductive polarity are applied to the Y electrode as shown in the figure so as not to discharge between the A electrode and the Y electrode. The voltage value of this pulse may be the same voltage as the pulse applied to the A electrode, but may be a voltage lower than this as long as the AY discharge can be prevented. A so-called wall voltage 11 due to wall charges formed by discharge changes as shown by a dotted line in the figure. In other words, a positive pulse applied to the A electrode causes a discharge between the AY electrodes, and a positive wall charge is formed on the X electrode side and a negative wall charge is formed on the A electrode side. The discharge again occurs at the time of falling, and the polarity of each wall charge when the discharge of P1 is finished is a negative charge in the X electrode and a slight positive wall charge is accumulated in the A electrode.

Next, the discharge 22 of P2 is performed between the A electrode 8 and the Y electrode 7. For this purpose, a pulse having a voltage sufficient to discharge between the Y electrode 7 and the A electrode 8 is applied. In the case of a positive column type PDP in which the distance between the XY electrodes is larger than the normal PDP, the influence of the discharge between AX performed at the timing of P1 is small on the X electrode immediately below the Y electrode, and the wall charge is also slight. AY discharge is easily caused by the pulse applied to the Y electrode. At this time, since the distance between the XY electrodes is large, no discharge occurs between the Y electrode and the X electrode, but a positive blocking voltage can also be applied to the X electrode for more stable operation. Thus, the discharge is performed at the fall as before, but the positive charges are accumulated in the Y electrode with respect to the polarity of each wall charge when the discharge of P2 is completed. The wall charge on the X electrode due to the discharge of P1 is not affected by the P2 discharge because the electrodes are separated from each other, and the negative charge remains accumulated, and the A electrode has a wall charge accumulated due to the structure. It is slight.

[Second Embodiment]
In the second embodiment shown in FIG. 3, the voltage distribution of the pulses of the A electrode and the Y electrode in the P1 discharge is changed. By applying a negative pulse to the X electrode side, the A electrode side pulse voltage is lowered. I can do it. Further, since the voltage of the A electrode is low, it is not necessary to apply a discharge blocking pulse to the Y electrode side. The P2 discharge is performed in the same manner as in FIG. 2, and negative and positive charges are accumulated in the X and Y electrodes, respectively, at the end of the reset discharge.

Thus, the present invention is a method of performing separate reset discharges between AX and AY, instead of performing reset discharge between XY electrodes as in the prior art, in a positive column type PDP having a wide discharge electrode. As in the first and second embodiments, the same operation is performed by changing the voltage distribution, but the pulse voltage distribution of each electrode has several combinations, but the basic operation is the same. Needless to say, the rising and falling edges of the reset pulse can be changed to a so-called ramp waveform as is generally done in the conventional reset discharge. In this case, the waveform and voltage distribution are different. As can be seen, the reset method of performing the inter-XA discharge and the XY discharge of the present invention at two consecutive timings P1 and P2 enables stable reset discharge even in a positive column type PDP having a wide gap between display discharge electrodes.

As described above, the reset method of the present invention is not limited to the three-electrode type PDP, and the display discharge electrode is a pair of electrodes parallel to each other as shown in FIG. Needless to say, the present invention can also be applied to a four-electrode PDP having a structure in which the display discharge electrode and the address electrode are separated.

Schematic sectional view of a PDP pixel showing the timing of reset discharge of the present invention Wall potential change due to reset pulse waveform and wall charge in the first embodiment of the present invention Changes in wall voltage due to reset pulse waveform and wall charge according to the second embodiment of the present invention Waveform of reset pulse explaining conventional reset method and change of wall voltage due to basic pulse waveform and wall charge to simplify operation explanation Schematic sectional view of a PDP pixel explaining a conventional reset method

DESCRIPTION OF SYMBOLS 1 Back side substrate 2 Back side dielectric layer 3 Front side dielectric layer 4 Front side substrate 6 Scan electrode or X electrode 7 Sustain electrode or Y electrode 8 Address electrode or A electrode 11 Wall voltage 20 due to wall charge 20 XA interelectrode discharge 21 XY electrode Interdischarge 22 YA Interelectrode Discharge P1 XA Discharge Timing P2 YA Discharge Timing

Claims (1)

  AC type PDP, that is, the surface of the discharge electrode is covered with a dielectric layer, and the charge accumulated in the dielectric layer is used, so-called wall charges, and a parallel discharge electrode, for example, a so-called scan electrode and a sustain electrode, and these In an AC type PDP which is composed of commonly called address electrodes arranged in a spatially intersecting manner, and the gap between the scan electrode and the sustain electrode is relatively large, for example, 200 microns or more, before each display cycle In the so-called PDP resetting method in which the wall charge formed by the discharge of the cycle is restored to the state of the wall charge uniform on the entire screen, the reset is not performed by the discharge between the scan electrode and the sustain electrode, but the scan electrode and the address electrode , Separate discharges at continuous timing between the sustain electrode and address electrode, and uniform across the entire screen AC type PDP reset method of forming the state of charge.

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