JP2745548B2 - Driving method of plasma display - Google Patents

Description

The present invention relates to a driving method of a plasma display,
Especially, AC refresh type plasma display (PDP)
In the driving method of

[Conventional technology]

Conventionally, as a driving method of this type of AC refresh type plasma display (PDP), a voltage waveform applied to one of an external electrode group facing each other via an insulator and a discharge space is time-divided. In the other electrode group, the pulse waveform of the opposite phase is applied to the voltage waveform applied to the one electrode group when the light is turned on, and the same phase voltage is applied when the light is not turned on. A method to achieve stable operation by applying voltage
At -48318.

[Problems to be solved by the invention]

The conventional driving method described above is a method of driving by applying a pulse voltage of the opposite phase and the same phase to each electrode of the electrode group formed on the same insulator, corresponding to lighting and non-lighting, Electrically, a driving circuit is coupled via a stray capacitance between the respective electrodes, and a load applied to the driving circuit varies depending on a display pattern. For this reason, there is a drawback that a change in load due to a difference in the number of lit dots during one scanning period causes a slight change in the waveform of the pattern-like voltage applied to the scanning-side electrode, which results in a change in brightness.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a driving method of a plasma display which eliminates the above-mentioned disadvantages of the conventional driving method and has no brightness contrast.

[Means for solving the problem]

According to the present invention, a voltage is sequentially applied to one scanning electrode group of a plasma display panel in which electrodes are coated with a dielectric in a time-division manner, scanning is performed, and the scanning is performed in synchronization with the voltage applied to each scanning electrode. In a refresh driving method of a plasma display in which a voltage is applied to another data-side electrode group according to the presence or absence of data to drive the same, the number of lighting data in input data is counted for each scanning period,
The number of pulses of the pulse-like voltage applied during one scanning period in which the input data is displayed is varied according to the number of lighting data.

〔Example〕

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

In the plasma display to which the driving method of the present invention is applied, two glass plates each having an electrode group covered with a dielectric are formed by opposing each other, the respective electrode groups are orthogonal, and the intersection is a light emission for display. Designed to be a point.
In order to drive this plasma display panel, the first electrode is generally selected only for the H period by the horizontal synchronization signal shown in FIG. 2 (e), and the peak value V ₀ shown in FIG. 2 (a) is selected. Is applied to the first electrode. In the case of a panel having m horizontal electrodes and n vertical electrodes, n vertical electrodes are selected and driven for the first horizontal electrode. Next, after a certain period (a blanking period), the second electrode is selected and, like the first electrode, H is selected.
Pulse voltage having a peak value of V ₀ shown in only FIG. 2 (b) period is applied to the second electrode. A pulse-like voltage is applied to the third electrode after a pulse-like voltage is applied to the second electrode, and thereafter this scanning is sequentially repeated, and a period (V) until a vertical synchronizing signal is input. Continue. Fig. 2 (d)
The first electrode is returned to a state in which the first electrode can be selected by the vertical synchronization signal. That is, the scanning of the method is sequentially performed by the horizontal synchronization signal, and is returned to the original state by the vertical synchronization signal input after all the aqueous electrodes are scanned. The vertical synchronizing signal matches the refresh frequency of the display, and is generally selected for 60 cycles or more. On the other hand, the number of horizontal synchronization signals included in one period of the vertical synchronization signal matches the number of scanning lines. However, in general, the number of scanning lines does not match the number of scanning electrodes of the panel, and the number of scanning lines is smaller than the number of scanning electrodes of the panel. There are many.

FIG. 3 (a) shows the pulse voltage applied to the first row electrode, and FIGS. 3 (b) and (c) show the pulse voltage applied to the m-th column and n-th column electrodes, respectively. It is shown. FIGS. 3 (d) and 3 (e) are discharge light emitting points (1 row and m column) formed at the intersections of the first row electrode and the m-th example electrode and the n-th column electrode, respectively. 3 shows a voltage waveform applied to a (row, n column) cell.

The operating principle of lighting and non-lighting has already been described in
As disclosed in 48318, the brief description is as follows. Since the voltage waveform applied to the m-th column electrode has the opposite phase to the voltage waveform applied to the first row electrode (1 row, m column), the cell is in the lighting mode. On the other hand, the n-th
The pulse voltage applied to the column electrode is in phase with the pulse voltage applied to the first row electrode (first
The (row, n column) cell is in the non-lighting mode, that is, the light-off mode. (1 row, m column) The pulse voltage applied to the cell is represented by the potential difference between the pulse voltage applied to the first row electrode and the m-th column electrode, and has a waveform shown in FIG. 3 (d). (First
Similarly, the pulse voltage applied to the (row, n column) cell is represented by a potential difference as shown in FIG. 3 (e).

The potential difference applied to these cells is determined as follows. Between the electrodes of the plasma display panel,
When driving by applying a pulsed voltage, a pulse voltage is applied to only one electrode and the other electrode is kept at 0 potential to cause a discharge between the electrodes. One discharge cell in the plasma display panel The discharge voltage is the minimum discharge start voltage (VD _min ), and the discharge voltage of all the cells of the plasma display panel is the maximum discharge start voltage (VD _min ).
_maX ), a pulse-like voltage (V0) higher than VD _{min and} lower than VD _max is applied to one electrode of the plasma display, and the other electrode is applied with a reverse phase,
When the in-phase pulsed voltage (V1) is applied, VD _min > | V0 |
When the condition of − | V1 | is satisfied, the discharge stops and VD _maX <| V0
Discharge starts when the condition of | + | V1 | is satisfied. As described above, lighting / non-lighting of all the dots can be selected, and a desired display can be performed.

Next, FIG. 1 showing a timing chart of the voltage arrangement of the first embodiment according to the present invention will be described. FIG. 1A shows the same horizontal synchronization signal as FIG. 2E, FIG. 1B shows a data clock signal for reading data, and FIG. 1C shows data for determining a display pattern. The signals, FIGS. 1 (d), (e) and (f) are the i-th and i-th, respectively.
+1 and i + 2 are scanning-side pulse voltages applied to the rows. The data signal shown in FIG. 1C is synchronized with the data clock signal shown in FIG. 1B, and can be changed to a high level when lit for each clock and to a low level when not lit for each clock. Here, for simplicity, it is as shown in FIG. In general, when a desired display is to be performed during a certain scanning period, a data signal for determining the display is read during the immediately preceding one scanning period. In FIG. 1, the data signal for determining the display in the period b is read in the period a. Here, looking at the data signal in the period a, the first three quarters are at the low level, that is, not lit, and the subsequent quarter period is at the high level, that is, lit. On the display, the left three-quarters of the row are turned off, and the right one-quarter is turned on, and the display is performed in the i-th row during the period b. At the same time, the display data of the (i + 1) th row is input, and the data is that the left half is turned on and the right half is turned off. The display data of the (i + 2) th row inputted when the left half is turned on and the right half is turned off in the (i + 1) th row are all turned on. In the AC refresh type driving method of the present invention, the display luminance is proportional to the number of discharge pulses in each scanning period.
Fall time also has an effect on brightness. That is, as the rise time and the fall time become longer, the brightness becomes darker. The larger or smaller number of lighting dots in each scanning period affects the waveform of the pulse-like voltage applied to the scanning electrode, and as the number of lighting dots increases, the waveform becomes dull and the rise time / fall time becomes longer. That is, as the number of display dots increases, the brightness decreases. Therefore, since the luminance when all the dots in one scanning period are lit is the darkest, when the number of lit dots is small, the i-th row and the (i + 1) -th
If the number of pulses is appropriately reduced like a pulse voltage applied to a row, brightness does not increase or decrease.

As described above, in this embodiment, the number of lighting dots in one scanning period is counted, and when the number of lighting dots is small, the number of pulses of the pulse voltage applied in one scanning period is reduced, and the number of lighting dots is large. In such a case, the number of pulses of the pulse voltage is increased to prevent the occurrence of brightness brightness.

FIG. 4 is a timing chart of the voltage arrangement according to the second embodiment of the present invention. In this case, the frequency is reduced as a method of reducing the number of pulses of the pulse-like voltage applied to the i-th row and the (i + 1) -th row. Apart from this, the others are the first
This is exactly the same as the embodiment.

Note that not only the scanning side but also the waveform of the discharge pulse applied to the data side electrode changes depending on the number of lit dots and the adjacent state of the lit / unlit dots. In general, the peak value of the discharge pulse applied to the data side electrode is Because it is lower than the scanning side,
There is not much effect on brightness.

〔The invention's effect〕

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

[Brief description of the drawings]

FIGS. 1A to 1F show timing charts of voltage arrangement according to a first embodiment of the present invention, and FIGS. 2A to 2F.
(E) is a diagram showing a timing chart of a pulse-like voltage applied to the scanning electrode, and (a) to (e) of FIG.
FIG. 4A to FIG. 4F show the relationship between the pulse voltage on the scanning side and the pulse voltage on the data side in each case of non-lighting, and FIG. 4A to FIG. FIG.

Claims (1)

(57) [Claims] 1. A voltage is sequentially applied to one scanning electrode group of a plasma display panel in which electrodes are coated with a dielectric in a time-division manner, and scanning is performed, and the voltage is synchronized with the voltage applied to each scanning electrode. Then, in a refresh driving method of a plasma display in which a voltage is applied to another data-side electrode group according to the presence or absence of data, the number of lighting data of input data is counted for each scanning period, and this input data is A method for driving a plasma display, wherein the number of pulses of a pulse-like voltage applied during one displayed scanning period is varied according to the number of lighting data.