JPH11143425A - Driving method of ac type pdp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve luminance and luminous efficiency merely via the change of a driving method by applying a fine-width pulse not necessarily quenching all negative wall charges, and inducing a discharge between a pair of sustain electrodes with this pulse used as a trigger. SOLUTION: A discharge between a first address electrode 8 and a second address electrode 2 is induced for a very short time, i.e., the application of this pulse is completed when part of the negative wall charges of the second address electrode 2 are erased or at least before positive wall charges are accumulated. The discharge starting voltage between the second address electrode 2 and a sustain electrode 3 is very low, and a discharge is restarted by the voltage slightly higher than a discharge maintenance voltage. The discharge between the first address electrode 8 and the second address electrode 2 is supplementally used as a so-called trigger for a sustain discharge, thereby a PDP can be driven by a low voltage, and luminance and luminous efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for driving an AC plasma display panel, that is, an AC PDP.

[0002]

2. Description of the Related Art For example, in a conventional three-electrode surface discharge type ACPDP as shown in FIG. 3, in an address period, an XY composed of a first address electrode 8 and a second address electrode 2 opposed to each other across a gas space. First, an address discharge occurs in the matrix, and charges are accumulated in the second address electrode 2 having a structure in which an AC electrode, that is, a surface is covered with a dielectric layer to form a capacitance thereon. This is called a wall charge. Since no wall charge is generated in the pixel where the address discharge does not occur, that is, the pixel is not selected, the wall charge is selectively distributed to each pixel after the end of the address period.

[0003] Then, the second address electrode 2 and
If a pulse is applied between the electrode and the sustain electrode 3 arranged in parallel, a discharge corresponding to the wall charge distribution is selectively generated. Since the second address electrode 2 and the sustain electrode 3 are AC electrodes, if a continuous AC pulse, that is, a sustain pulse is applied between the two electrodes, memory discharge display can be performed. FIG. 2 shows the timing of the pulses and the state of the wall charges during the sustain discharge period. In the figure, the wall voltage generated by the wall charge is indicated by a broken line so as to be superimposed on each applied voltage pulse waveform.

[0004] The sustain discharge occurs when the sum of the voltage due to the wall charge formed by the address discharge and the sustain pulse voltage applied between the two electrodes exceeds the discharge starting voltage between the two electrodes. On the other hand, it is needless to say that the driving voltage of the PDP is desirably as low as possible. However, the discharge starting voltage of the PDP generally becomes lower as the distance between the electrodes becomes smaller and the driving voltage decreases under a certain gas pressure. However, in the case of a color PDP, in order to cause the phosphor to emit light by ultraviolet rays generated by the discharge, it is preferable to increase the distance between the electrodes to increase the discharge space, thereby increasing the luminous efficiency.
It has been confirmed from both theoretical and experimental viewpoints that the luminance increases.

For example, typical dimensions in a practical PDP having a structure as shown in FIG. 3 preferentially determine the distance between the first address electrode 8 and the second address electrode 2 for stable driving. Usually, the height of the partition wall for determining this is about 0.1 mm, and the gas pressure and the like are optimized accordingly.
On the other hand, as described above, between the second address electrode 2 and the sustain electrode 3, as the sense is wider, the luminance characteristic is improved, and when this is extended to about 1.0 mm or more, the light is used as a source of ultraviolet light in a normal PDP. It is known that a positive column having a higher ultraviolet emissivity than a negative glow is generated, and a significant improvement in luminance characteristics can be expected. For the above reasons, the distance between the electrodes is desired to be significantly wider than 0.1 mm, but cannot be widened in order to suppress an increase in the firing voltage. Therefore, in a practical PDP, the second address electrode 2 and the sustain electrode 3 are formed of transparent electrodes,
The gap between the electrodes is maintained at about 0.1 mm, and the electrodes are driven at a voltage substantially equal to the discharge start voltage of the first address electrode 8 and the second address electrode 2.

However, with such a short gap discharge, both luminance and luminous efficiency cannot be increased. Therefore, as one of the structural ideas, the antenna-like electrodes protrude from both electrodes of each pixel, apparently reducing the distance between the electrodes and lowering the firing voltage,
However, there are PDPs in which the electrodes of the main discharge portion are separated from each other and have a larger area than that of the protruding portion so that the discharge is performed in a substantially wide discharge gap.
In this case, there is a problem that alignment of the upper and lower glass substrates becomes difficult.

[0007]

As described above, the distance between the sustain electrodes is increased in order to increase the luminous efficiency and the luminance of the sustain discharge, which is the display discharge, but the discharge starting voltage is prevented from being increased accordingly. Therefore, it is intended to solve the problem only by improving the driving without complicating the panel structure.

[0008]

As described above, the discharge starting voltage of a PDP generally increases with the distance between the electrodes under a certain gas pressure, but the discharge sustaining voltage increases with the formation of a negative clock after the start of the discharge. In this case, the electric field generated by the space charge layer generated very close to the cathode governs the discharge sustaining characteristics, so that the influence of the distance between the electrodes is small. That is, once the discharge starts, the discharge can be maintained at a low discharge voltage even if the distance between the electrodes is large.

Utilizing this property, in the present invention, for example, in the structure of FIG.
Not only between the address electrode 2 and the sustain electrode 3, but also at the time of applying each sustain pulse, first, the first address electrode 8 and the second address electrode 2 having a narrow gap between the electrodes.
Alternatively, a preliminary discharge is performed between the first address electrode 8 and the sustain electrode 3, and then a main discharge is performed between the first address electrode 8 and the sustain electrode 3 having a wide gap between the electrodes. Here, the main idea that constitutes the present invention is that the discharge time of the preliminary discharge is set to be very short as compared with the main discharge time.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a timing chart of a sustain pulse showing one embodiment of the present invention. The structure of a PDP to which this is applied for description is a conventional so-called three-electrode surface discharge type PDP shown in FIG. However, if the driving method of the present invention has a pair of sustain electrodes and a third electrode such as an address electrode opposed thereto, as shown in FIG.
It is needless to say that the present invention can be applied to panels having other structures.

The timing chart of FIG. 1 shows only the sustain period. In the address period before this, the address discharge between the first address electrode 8 and the second address electrode 2 in accordance with an image during the address period is performed. Second address electrode 2
This indicates that the sustain period has started from a state in which negative wall charges are formed on the surface of the substrate and positive wall charges are formed on the sustain electrode 3. The wall voltage due to the wall charges is shown by a broken line, and is shown as being superimposed on the sustain pulse voltage waveform. Second address electrode 2
The sustain electrode 3 has an AC electrode structure, but the first address electrode 8 may be a DC type or an AC type. Here, the first address electrode 8 is of a DC type, so that accumulation of wall charges does not occur during operation.

When a negative-polarity pulse is applied to the second address electrode 2 having a negative wall charge, the voltage is superimposed on the discharge voltage, and a voltage higher than the applied voltage is applied between the electrodes. Occurs. However, in the case of a PDP having a normal structure, a discharge starts. However, if the space between the second address electrode 2 and the sustain electrode 3 is widened to, for example, about 0.6 mm in FIG. 3, no discharge occurs at the conventional sustain voltage. . That is, even if the wall voltage due to the address discharge is superimposed, the sustain discharge does not occur.

However, if a positive pulse is applied to the first address electrode 8 at this time, the first address electrode 8 and the second
A discharge occurs between the address electrodes 2. If the discharge at this time is longer than a certain time, the negative wall charges on the second address electrode 2 are erased, and after a lapse of further time, the positive wall charges are formed again. In this case, the potential difference between the second address electrode 2 and the sustain electrode 3 becomes small, so that the discharge between the second address electrode 2 and the sustain electrode 3, that is, the sustain discharge does not occur.

Therefore, in the driving method of the present invention, the discharge between the first address electrode 8 and the second address electrode 2 is performed in a very short time, that is, a part of the negative wall charge of the second address electrode 2 is erased. This pulse application is terminated before the accumulation of at least the positive wall charges. Within this time, when the pulse stops, the space charge due to the discharge still remains in the discharge space. Accordingly, the discharge starting voltage between the second address electrode 2 and the sustain electrode 3 is very low, and the re-discharge is slightly higher than the sustaining voltage. Once the discharge is started, the sustaining voltage is not sensitive to the distance between the electrodes, so that a normal sustain discharge can be performed. In this manner, by using the discharge between the first address electrode 8 and the second address electrode 2 as a trigger for the sustain discharge as a trigger, the PDP structure can be extended even if the distance between the electrodes is increased. Since the driving voltage can be driven at a low voltage without being changed, the luminance and the luminous efficiency can be improved.

As shown in FIG. 1, the first address electrode 8
The reason why the polarity of the narrow pulse applied to the first address electrode is made positive is that the first address electrode side is usually coated with a phosphor, and the electrodes are not usually provided with a protective measure such as a protective layer. This is because it is necessary to avoid ion bombardment.
Depending on the voltage application method at the time of addressing, the sustain electrode side may have negative wall charges after the end of the address period. In this case, auxiliary discharge is performed between the first address electrode 8 and the sustain electrode 3. It goes without saying that this is the case.

[0016]

According to the driving method of the present invention, the discharge starting voltage does not increase even if the gap between the electrodes performing the sustain discharge is widened, and therefore, the improvement of the luminance and the improvement of the luminous efficiency greatly improve the panel structure. This can be achieved only by changing the driving method regardless of the change, and the power consumption of the driving circuit can be reduced due to the effect of reducing the driving voltage.

[0017]

[Brief description of the drawings]

FIG. 1 is a timing diagram of a sustain pulse according to a new driving method. A, applied pulse of a second address electrode, broken line is wall voltage B, applied pulse of sustain electrode, broken line is wall voltage C, applied pulse of first address electrode.

FIG. 2 is a timing chart of a sustain pulse according to a conventional driving method. D, applied pulse of a second address electrode, broken line is wall voltage E, applied pulse of sustain electrode, broken line is wall voltage F, applied pulse of first address electrode.

FIG. 3 shows a structure of a three-electrode surface discharge type ACPDP.

[0018]

[Explanation of symbols]

 Reference Signs List 1, front glass 2, second address electrode 3, sustain electrode 4, dielectric layer 5, protective layer 6, partition 7, phosphor 8, first address electrode

Claims (1)

[Claims] In a PDP having an address electrode and a pair of sustain electrodes arranged so as to intersect with the address electrode, for example, a three-electrode surface discharge type AC PDP, an address operation, that is, a distribution of wall charges according to an image is determined by a sustain electrode. In the sustain operation, that is, the operation of continuously applying an AC voltage pulse between the pair of sustain electrodes and selectively performing a sustained display discharge based on the wall charge distribution, the AC operation is performed. At the same time as the application of the voltage pulse, a narrow pulse of the positive polarity is applied to the address electrode, that is, a discharge is performed for a very short period between the pair of sustain electrodes and the electrode on which the negative wall charge is formed. An AC-type PDP in which a narrow pulse that does not completely extinguish is applied and a discharge is generated between the pair of sustain electrodes by using this as a trigger Drive method.