JPH03179489A - Driving method for plasma display panel - Google Patents

Abstract

PURPOSE:To obtain the effect of priming without decreasing the contrast nor the color purity by setting the rising of a voltage pulse for preliminary discharging later than the rising of a voltage pulse for the discharging of a screen display. CONSTITUTION:A pulse waveform 1 in a display discharge period is a normal fast rising rectangular waveform, but a pulse waveform 2 in a preliminary discharging period rises slower than a pulse waveform in a display discharging period. A pulse which has high light emission efficiency of vacuum ultraviolet light and rises fast is used as the pulse for display discharging and a pulse which is low in the light emission efficiency and rises slowly is used for preliminary discharging, so the contrast and color purity has a little deterioration even after the priming, whose effect has no variation. Consequently, the inferiority of the contrast and color purity is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to dot matrix type plasma display panels used in personal computers, office workstations, which have made rapid progress in recent years, and wall-mounted televisions, which are expected to develop in the future. Regarding the driving method.

[Prior Art] FIG. 4 shows a cross-sectional view of the structure of an AC type plasma display panel, taking a surface discharge type color plasma display as an example. As shown in FIG. 4, a glass substrate 6 on which electrodes 5 are formed is covered with an insulating layer 7, and a protective layer 15 is formed thereon. A data electrode 16 is formed on the opposing glass substrate 13, and a phosphor 12 is formed thereon. These two glass substrates 6 and 13 are hermetically sealed with a partition wall 11 in between, and a rare gas 10 is sealed inside. The rare gas 10 is usually a mixed gas of He and Xe.

A plasma 8 is generated by the discharge between the electrodes 5 and 16, and the vacuum ultraviolet light 9 emitted from the plasma excites the phosphor I2 to emit light, thereby obtaining visible light 14. Since the AC type plasma display panel has a memory function, data electrode 16 and electrode 5
The display can be controlled by inputting a write pulse and an erase pulse to. In order to display gradation, the L field that displays one screen is divided into a plurality of subfields. An example of a time chart divided into seven fields is shown in FIG. The horizontal axis is time, and the vertical axis is each electrode (electrode S
,~den tfl! S, ), and the shaded area indicates the time period during which light can be emitted. 6 out of 7 fields (1st
The subfields to the sixth subfield) are used for display, and this combination displays 2 degrees, or 64 gradations. The remaining one field is a subfield for preliminary discharge, and a priming discharge occurs in this subfield.

As a result, there is a period in one field in which all the discharge cells discharge at least one time, and 71 charged particles are always present in all the discharge cells. Therefore, even in the discharge after a display pattern that does not discharge for a long time, charged particles are always present (/:, so it is possible to prevent i'F writing errors. The drive waveform is shown in Fig. 2. The waveform shows the potential difference between the electrodes.The pulse waveform 4 in the pre-discharge period is the same as the pulse waveform 3 in the display discharge period.However, even in a display pattern with no discharge for a long period of time, priming can be ensured. The applied voltage is slightly higher than the pulse of the display discharge so that discharge occurs.Since the waveforms are the same, the discharge characteristics of the display discharge and the preliminary discharge are exactly the same.

[Problems to be Solved by the Invention] However, since visible light is also generated by the priming discharge, the contrast of the plasma display panel is reduced and the color purity is also reduced. These have a very large adverse effect on the display quality of the display.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for driving a plasma display panel that provides a priming effect without reducing contrast and color purity.

[Means for Solving the Problems] In order to achieve the above object, in the method for driving a plasma display panel according to the present invention, the L field period for displaying one screen using an AC dot matrix type plasma display panel is provided. divided into a plurality of subfields, at least one of the subfields;
A method for driving a plasma display panel in which a preliminary discharge is caused to occur within two subfield periods, and the rise of a voltage pulse that generates the preliminary discharge is set later than the rise of a voltage pulse that generates a screen display discharge. .

r Effect] By using the above-described driving method of the present invention, the priming effect can be obtained without reducing contrast and color purity. That is, by slowing down the rise of the priming pulse, the generation efficiency of vacuum ultraviolet light is lowered, the generation of visible light is suppressed, and a decrease in contrast and color purity is prevented. In the case of a sufficiently fast-rising pulse, the electrons in the discharge cell are accelerated before the electric field in the discharge space is weakened by the space charge caused by collision ionization, which makes the Xe in the mixed gas more efficient in emitting vacuum ultraviolet light. It can be excited up to the level. However, when the pulse rises slowly, space charges increase due to impact ionization and the electric field weakens before the pulse rises to a voltage that sufficiently accelerates the electrons. Therefore, electrons are not sufficiently accelerated and the luminous efficiency of vacuum ultraviolet light is low. This suppresses the generation of visible light due to the priming pulse, and prevents deterioration of contrast and color purity. Further, since discharge occurs even with a slow rising pulse, sufficient charged particles are generated, and the priming effect remains unchanged.

[Example 1 Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing drive waveforms in the present invention.

The time chart of applied voltage pulses used in the present invention is the same as that shown in FIG. 3 for the conventional method.

The drive waveform shown in Figure 1 shows the potential difference between the electrodes,
The horizontal axis is time and the vertical axis is applied voltage. The pulse waveform l during the display discharge period is a normal square wave with a fast rise, but
The pulse waveform 2 in the preliminary discharge period rises later than the pulse waveform in the display discharge period. In the case of a sufficiently fast-rising pulse, the electrons in the discharge cell are accelerated before the electric field in the discharge space is weakened by the space charge caused by collision ionization, which allows Xe in the mixed gas to emit vacuum ultraviolet light more efficiently. can be excited to a level that However, if the pulse rises slowly, the space charge increases due to impact ionization and the electric field weakens before the pulse rises to a voltage that sufficiently accelerates the electrons. Therefore, electrons are not sufficiently accelerated and the luminous efficiency of vacuum ultraviolet light is low. The purpose of the priming discharge during the preliminary discharge period is to eliminate write errors by creating charged particles within the discharge cell. As long as charged particles are generated, the lower the luminous efficiency of vacuum ultraviolet light, the better in terms of contrast and color purity. In the present invention, a fast-rising pulse with high vacuum ultraviolet light emission efficiency is used for the display discharge pulse, and a slow-rising pulse with low luminous efficiency is used for the preliminary discharge, so even if priming is performed, There is almost no loss of contrast or color purity. Of course, the effect of priming is no different from that of conventional waveforms.

Next, we will explain by showing the specific numbers.The structure of the panel used in the experiment is the same as that explained in the conventional technology, the discharge gap is 0.1M, the gas is a mixed gas of tle+Xe (2%), The gas pressure is 200 torr.In Figure 1, the pulse width of pulse waveform 2 during the preliminary discharge period is 211
sec, the rise time was 11 sec, and the applied voltage was 30% higher than the display discharge pulse in order to ensure the generation of preliminary discharge. At this time, the luminous efficiency of the vacuum ultraviolet light of the preliminary discharge pulse is about 1/4 of the pulse waveform 1 of the display discharge period, which rises sufficiently quickly. On the other hand, in the conventional pulse waveform shown in FIG. 2, pulse waveform 3 in the display discharge period and pulse waveform 4 in the preliminary discharge period have the same rise and fall, and the luminous efficiency of vacuum ultraviolet light is also the same. Therefore,
Contrast can be improved by four times compared to conventional models in the dark, and nearly twice as much in indoor light. Furthermore, since the amount of visible light emitted by priming was reduced to 1/4, the color purity was improved and the display quality was improved. Of course, the priming effect is the same as the conventional method, and it goes without saying that no lighting errors are observed. In the above waveform example, the rising edge is 1 psec for a pulse width of 2 psec, but in principle, it is effective if the rising edge of the preliminary discharge pulse is even slightly slower than the display discharge pulse. However, in practical terms, it is more effective to make the rise slower than the discharge delay time of several hundred n5 eC when a pulse with a sufficiently fast rise is applied.

〔Effect of the invention〕

As described above, by using the present invention, it is possible to improve the poor contrast and color purity, which are the drawbacks of the conventional method, while maintaining the effects of conventional priming using preliminary discharge. This has made it possible to create high-quality plasma displays that combine fast response, high gradation reproducibility, high contrast, and good color reproducibility.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the driving waveform in the present invention, Fig. 2 is a diagram showing the conventional driving waveform, Fig. 3 is a time chart with a preliminary discharge period, and Fig. 4 is an AC surface discharge type color plasma. FIG. 3 is a sectional view showing the display.

Claims (1)

[Claims] (1) One field period for displaying one screen using an AC dot matrix type plasma display panel is divided into a plurality of subfields, and a preliminary discharge is caused to occur within at least one subfield period among the subfields. 1. A method for driving a plasma display panel, the method comprising: setting the rise of the voltage pulse that generates the preliminary discharge to be later than the rise of the voltage pulse that generates the discharge of screen display.