JPH0239092A - Method for driving plasma display - Google Patents

Abstract

PURPOSE:To prevent the generation of a bright and dark difference in a luminance by changing the number of discharging pulses according to the number of light-up data in display data for each one scanning period. CONSTITUTION:A data signal synchronizes to a data clock signal, and it can be changed to a High level and to a Low level at the time of a light-up a the time of a non-light-up, respectively, for each one clock. In such a case, the number of light-up dots in one scanning period is counted, the number of the pulses of a pulse voltage impressed in one scanning period is decreased when the number of light-up dots is small, the number of pulses of the pulse voltage is made large when the number of light-up dots is large, and thereby, the generation of the bright and dark difference in the luminance is prevented. Thus, a plasma display without the bright and dark difference in the luminance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for driving a plasma display, and particularly relates to a method for driving a plasma display (AC refresh type plasma display).
).

[Conventional technology]

Conventionally, as a driving method for this type of AC refresh type plasma display (PDP), the voltage waveform applied to either one of the external electrode groups facing each other through an insulator and a discharge space is applied in a time-division manner. When the voltage waveform applied to the one electrode group is turned on, a pulse voltage with the opposite phase is applied to the other electrode group, and when the voltage waveform is not turned on, a voltage with the same phase is applied to the other electrode group. Japanese Patent Publication No. 55-48318 discloses a method for achieving stable operation by applying .

[Problem to be solved by the invention]

In the conventional driving method described above, each electrode of a group of electrodes formed on the same insulator is set to have an opposite phase, depending on whether it is lit or not.
Since this is a method of driving by applying pulse voltages of the same phase, the drive circuits are electrically coupled via the stray capacitance between the respective electrodes, and the load on the drive circuits varies depending on the display pattern. For this reason, there is a drawback that a fluctuation in the load due to a difference in the number of lit dots during the -scanning period causes a subtle change in the waveform of the pulsed voltage applied to the scanning side electrode, which causes brightness to become brighter or darker.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for driving a plasma display that eliminates the drawbacks of the conventional driving methods described above and eliminates brightness variations.

[Means to solve the problem]

In the present invention, a voltage is sequentially applied in a time-division manner to one scanning electrode group of a plasma display panel whose electrodes are covered with a dielectric material, and scanning is performed. i! In a plasma display refresh drive method in which a voltage is applied to other data-side electrode groups according to the presence or absence of data in synchronization with the voltage applied to the %, the lighting data in the input data is refreshed every scanning period. The present invention is characterized in that the number of pulses of the pulse voltage applied during one scanning period during which this input data is displayed is varied according to the number of lighting data.

〔Example〕

Next, a detailed explanation will be given with reference to the drawings. FIG. 1 is a timing chart of voltage arrangement according to the first embodiment of the present invention. FIG. 2 is a timing chart for explaining the timing of pulsed voltages applied to the scanning electrodes. FIG. 3 is a timing chart for explaining the timing of lighting and non-lighting.

A plasma display to which the driving method of the present invention is applied has two glass plates each having a group of electrodes covered with a dielectric material.
The electrode groups are designed to face each other, intersect perpendicularly, and the intersection becomes a light emitting point for display. To drive this plasma display panel, generally a second
The first electrode is selected for the H period by the horizontal synchronization signal shown in Figure (e), and a pulsed voltage having a peak value VO shown in 211% (a) is applied to the first electrode. Ru. In the case of a panel with m horizontal electrodes and n vertical electrodes, a fixed period (blanking period) is set in the primary mode in which n vertical electrodes are selected and driven for the first horizontal type. Then, the second electrode is selected, and a pulsed voltage having a peak value of o shown in FIG. 2(b) is applied to the second electrode only during the H period, similarly to the first electrode. A pulsed voltage is applied to the third electrode after the pulsed voltage is applied to the second electrode, and this operation is repeated one after another until the vertical synchronization signal is input (V). Continue.

The vertical synchronization signal shown in FIG. 2(d) returns the state in which the first electrode can be selected. That is, in the scanning method of this method, the horizontal synchronizing signal is used to scan sequentially, and after all the horizontal electrodes have been scanned, the original state is restored by the input vertical synchronizing signal. The vertical synchronization signal matches the refresh frequency of the display and is generally spread over 60 cycles or more. - On the other hand, the number of horizontal synchronization signals included in 1N of vertical synchronization signals matches the number of scans, but in -i, the number of scans does not match the number of scan electrodes of the panel, and the number of scans does not match the number of scans of the panel. More than the number of electrodes.

FIG. 3(a) shows the pulsed voltage applied to the first row electrode, and FIGS. 3(b) and 3(c) show the m-th column and n-th column, respectively.
It shows the pulsed voltage applied to the column electrodes.

Figures 3(d) and (e) show a cell (1st row, mth column) and a (1st (row, n column) shows the voltage waveform applied to the cell.

The operating principle of lighting and non-lighting has already been published in
48318, but briefly described as follows. Although the voltage waveform applied to the m-th column electrode is in opposite phase to the voltage waveform applied to the first row electrode (1st row, 1mth column), the cell is in the lighting mode. on the other hand,
Since the pulsed voltage applied to the nth column electrode is in phase with the pulsed voltage applied to the first row electrode (first row, nth column), the cell is in the non-lighting mode, that is, the light-off mode. be. (1st row, m column) The pulsed voltage applied to the cell is expressed by the potential difference between the pulsed voltage applied to the 1st row electrode and the rnth column electrode, and has the waveform shown in FIG. 3(d). (
Similarly, the pulsed voltage applied to the cell (1st row, n column) is expressed as a potential difference as shown in FIG. 3(e).

The potential difference across these cells is determined as follows. When driving a plasma display panel by applying a pulsed voltage between the electrodes, applying the pulsed voltage to only one electrode and keeping the other electrode at zero potential to cause a discharge between the electrodes, the plasma The voltage at which one discharge cell in the display panel discharges is the minimum discharge start voltage (VD, 1.), and the voltage at which all cells in the plasma display panel discharge is the maximum discharge start voltage (VD, -x). When defined, a pulsed voltage (VO) higher than VD1□ and lower than VD□X is applied to one electrode of the plasma display, and a pulsed voltage with the opposite phase and the same phase is applied to the other electrode. When (Vl) is applied, the discharge stops when the condition of VD, +->VOI-IVII is satisfied, and VDmax < l VOl÷1■
When condition 11 is met, discharge starts.By selecting 0 or more, you can select whether all dots are lit or not.
Desired display can be performed.

Next, FIG. 1 showing a timing chart of voltage arrangement in a first embodiment of the present invention will be explained. Figure 1 (
a> is the same horizontal synchronizing signal as in Fig. 2(e), and Fig. 1(b)
) is a data clock signal for reading data, and FIG. 1(c) is a data signal that determines a display pattern.
Figure (d).

(e) and (f) are the tth, i+1. is the scan-side pulse voltage applied to the 12th row.

The data signal in FIG. 1(c) is synchronized with the data clock signal in FIG. 1(b), and can be changed to High level if it is lit every clock, and to Low level if it is not lit. , here, for simplicity, as shown in FIG. 1(c). Now, when a desired display is to be performed during one scanning period at -m, the data signal that determines the display is read during the previous one scanning period. In FIG. 1, the data signal that determines the display of period b is read in period a. Here, looking at the data signal for period a, the first three-quarters of the period is at a low level, that is, not lit, and the last one-fourth period is at a high level, that is, lit. left three quarters
is off and the right quarter is on, which is displayed in the i-th line during the period b. At the same time, the display data of the i+1th row is input, and is data in which the left half is on and the right half is off. When the i+1st line displays that the left half is on and the right half is off, the input display data on the i+2nd line is all on (0) In the AC refresh type drive system of the present invention, the display brightness is proportional to the number of discharge pulses within each scanning period, but the rise time and fall time of this discharge pulse also have an influence on the brightness. That is, as the rise time and fall time become longer, the brightness becomes darker. The number of lit dots in each scanning period affects the waveform of the pulsed voltage applied to the scanning electrode, and as the number of lit dots increases, the waveform becomes dull and the rise time and fall time become longer. In other words, the brightness becomes darker as the number of display dots increases. Therefore, since the brightness is the darkest when all the dots are lit within the -scanning period, when the number of lit dots is small, the i-th row and the i-th
If the number of pulses is appropriately reduced, such as with the pulsed voltage applied to the +1 line, brightness will not vary.

In this way, in this embodiment, the number of lit dots within a scanning period is counted, and if the number of lit dots is small, the number of pulses of the pulse voltage applied within one scanning period is reduced, and when the number of lit dots is large, the number of pulses of the pulse voltage applied within one scanning period is In some cases, the number of pulses of the pulse voltage is increased to prevent brightness from becoming bright or dark.

FIG. 4 is a timing chart of voltage arrangement according to the second embodiment of the present invention. In this case, the first line.

In order to reduce the number of pulse-like voltages applied to the i+1th row, the frequency is lowered. Other than this, everything else is exactly the same as the first embodiment.

Note that the waveform of the discharge pulse applied to the data side electrode as well as the scan side changes depending on the adjacency of the lit and non-lit dots, but in general, the peak value of the discharge pulse applied to the data side electrode is: Since it is lower than that on the scanning side, it does not have much influence on brightness.

〔Effect of the invention〕

As described above, the present invention has the effect of eliminating brightness and darkness by changing the number of discharge pulses in accordance with the number of lighting data in display data for each scanning period.

[Brief explanation of the drawing]

FIGS. 1(a) to (f) are diagrams showing timing charts of the voltage arrangement of the first embodiment of the present invention, and FIGS. 2(a) to (f)
e) is a timing chart of the pulsed voltage applied to the scanning electrode, and Figures 3(a) to (e) show the relationship between the pulsed voltage on the scanning side and the data side in each case of lighting and non-lighting. FIGS. 4(a) to 4(f) are diagrams showing the second embodiment of the present invention.

Claims (1)

[Claims] A voltage is sequentially applied in a time-division manner to one scanning electrode group of a plasma display panel whose electrodes are covered with a dielectric material, and the other scanning electrodes are scanned in synchronization with the voltage applied to each scanning electrode. In a plasma display refresh drive method in which a voltage is applied to the data-side electrode group according to the presence or absence of data to drive the display, the number of lighting data of input data is counted every scan period, and one scan in which this input data is displayed. A method for driving a plasma display, characterized in that the number of pulses of a pulsed voltage applied during a period is varied according to the number of lighting data.