JPS593754B2 - Driving method for character display device using plasma display panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 5. The present invention relates to a method for driving a character display device using a plasma display panel.

A plasma display panel (hereinafter referred to as PDP) is
For example, as shown in FIG. 5, display is performed by a discharge spot of a discharge cell 10 formed at the intersection with an electrically driven X-direction electrode group, and the characteristics of a PDP discharge cell are well-known. , by applying a sustaining voltage Vs of an alternating voltage as shown in FIG. Causes spots.

Once this discharge cell is discharged, the load after the start of discharge is equivalently capacitive, and a charge 20 corresponding to the polarity of the applied voltage is accumulated in the dielectric layer covering the electrode, and the wall voltage Vq will occur.

When the polarity of the sustaining voltage is switched while this state is formed, the potential difference between this wall voltage Vq and the sustaining voltage Vs of the subsequent half cycle becomes greater than the ignition voltage Vf, and a discharge spot is subsequently generated. , thereby increasing the wall voltage V
q has the opposite polarity to the previous wall voltage. Therefore, in order to maintain discharge light emission, an alternating sustaining voltage V as shown in FIG.
s must be given between the two poles. On the other hand, full-matrix PDPs are equipped with 30 electrode groups in the X direction and 30 electrode groups in the Y direction to basically fill the entire screen so that light can be emitted anywhere within the screen. When displaying characters by selective display, there must be a gap between the characters, but this gap can be fixed at 35% in terms of area, so when used in a character display device, the electrodes arranged in XY As shown in Figure 2, the inside of the display screen, which is a collection of discharge spots that are the intersections of
... is a display area, and the outside part is a non-display area, and at both ends of the X and Y intersections existing in the L display area, a predetermined maintenance, ignition, and drive voltage is applied as a composite voltage of the X and Y component drivers. It is connected to each XY driver as shown in Figure 5, and the matrix in other areas is
The write driver is wired to only one side at a time, and a voltage is applied to help discharge the electrodes at the ends of the character display positions. That is, when discharging to display characters, a write pulse is applied, but when the sustaining voltage is applied after the application of the write pulse, in the middle part of the character display area,
Since sustaining voltages are simultaneously applied to adjacent electrodes, electric fields are superimposed and a sustaining discharge is easily performed. If it is left floating or grounded, in addition to the electric field being different from the center at these boundary areas, the rise of the sustaining voltage waveform will be blunted due to the increased load capacity and discharge will not easily occur. For this reason, as shown in Fig. 5, an attempt is made to apply an equivalent sustaining voltage to electrodes other than the character display area adjacent to the above-mentioned outer electrodes to help discharge, but for some reason, the electrodes to which the sustaining voltage was applied Discharge may occur.

In addition, Dwy and Dwx in the figure are write drivers that drive the Y-direction electrode and the X-direction electrode in a matrix, and Dsx and Ds.
Similarly, y is a sustain voltage driver that applies sustain voltages to the X-direction electrodes and the Y-direction electrodes in a matrix manner.

Further, CAi indicates a display area. Generally, in order to reduce costs, PDPs do not have a circuit that applies erase pulses to electrodes other than the character display area, so when a discharge occurs in the character display area, the power to the PDP must be turned off. There are disadvantages that cannot be avoided.

Furthermore, in addition to the above, it is also practiced to cause discharge to occur constantly around the PDP or in a part other than the character display area to send discharge ions to the surrounding area, thereby facilitating writing.

And this is called the ignition. Therefore, there is a large distribution of ions, especially in the electrode near the pilot flame, and a slight noise voltage may cause discharge to ignite even if a regular write pulse is not given. Since no erasing pulse is applied to the electrode, a problem arises in that discharge light emission continues unless the power is turned off. In order to cope with this, as mentioned earlier, electrodes that do not apply write pulses, that is, do not correspond to character display positions, are always kept at ground potential to prevent erroneous discharge ignition.

However, although this method is certainly effective in preventing erroneous ignition, in this case, the electric field conditions are different between the electrode near the center of the letter and the electrode dropped to ground potential, and the nucleus of the discharge generated from the pilot flame is It is easy for ions to recombine,
In particular, the intersection electrode that displays a cursor to indicate the position of displaying one character, as shown in CR in Figure 2, where the double dots are hidden areas, has both adjacent electrodes set to ground potential. The drawback is that it is easily influenced and difficult to ignite. In view of the above, an object of the present invention is to provide a driving method that eliminates such drawbacks.
The configuration is as described above in a character display device using a plasma display panel that displays by discharge spots of discharge cells formed at the intersection of an X-direction electrode group and a Y-direction electrode group, and maintains the discharge display by a sustaining voltage. The display screen formed by a group of discharge spots is divided into a character display area and an outside area, and a discharge maintaining voltage of intersection drive is supplied to the discharge spots forming inside the character display area, and an impedance is applied to the discharge spots forming the outside area. It is characterized by being configured so that a discharge sustaining voltage is supplied through the element, thereby applying an alternating voltage that rises slower than the sustaining voltage to the electrode group corresponding to the area other than the character display position. be.

In other words, changing the driving conditions inside the area and outside the area means configuring the driving conditions outside the area more gently. Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 is an explanatory diagram of an embodiment of the present invention, and FIG. 3A is an embodiment of the sustaining voltage driver circuit of the present invention, and shows one of the component drivers for driving the X electrode group or the Y electrode group. In particular, a resistor R is inserted and its output is applied to an electrode corresponding to a position other than the character display position. And from B,
The same maintenance voltage as the conventional device can be obtained. In addition, in FIG. 6, in order to divide the PDP in FIG. 5 into areas, the maintenance condition is that even for a group of electrode intersections that are not driven by the write driver, they are evenly connected to the sustain driver in the same way as within the area. On the other hand, the electrodes forming this region are connected through at least one of impedance (resistance in the figure) Zy or Zx, and the condition A is satisfied. As mentioned earlier, since the plasma light emitting element formed at the intersection is originally capacitive, an integrating circuit is formed with this impedance, and the waveform of the sustaining voltage is rounded, as shown in the output in Figure 4. The voltage amplitude is almost the same, but the change becomes gradual, making it difficult for the discharge to start.Also, even if the discharge does start, the wall voltage will only accumulate slowly, making it difficult to start the discharge in the next cycle. It becomes difficult to start and the discharge cannot be maintained, but on the other hand, the voltage amplitude does not change much, so the surrounding conditions are almost the same for the adjacent discharge spots in the area, and the adjacent discharge spots are driven by write 1. It is possible to maintain the ease of ignition when igniting, prevent ignition outside the area, and also eliminate the disadvantage that it is difficult to ignite the electrode elements at the edges and at the boundary with the outside area. I can do it.

In addition, by lowering the voltage of the power supply Vs in Fig. 3 and adding a special voltage in addition to the normal maintenance voltage driver using a circuit that removes the resistor R of A and the output B, the voltage of the power supply Vs in FIG. As shown in FIG. 4C, an alternating voltage lower than the sustaining voltage may be applied to electrodes corresponding to positions other than character display positions. At this time, a sustaining voltage is applied to the electrode corresponding to the character display position by a separate circuit from which the resistor R and output A in FIG. 3 are removed. As described above, according to the present invention, since a voltage with a gradual rise or a voltage lower than the sustaining voltage is applied to electrodes other than the character display position, it is possible to easily discharge the electrodes at the ends of the character display device. This makes it possible to prevent the discharge from continuing even if it occurs.

In addition, instead of resistor R, use a suitable capacitor C or inductor L.
A similar effect can be obtained by inserting an impedance in combination with the above and controlling the discharge.

Furthermore, in the above description, it goes without saying that the object of the present invention is not limited to such symmetrical sustaining voltages, but can be similarly applied to asymmetrical sustaining voltages to have similar effects.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram for explaining PDP operation, and FIG. 2 is a waveform diagram for explaining PDP operation.
Diagrams for explaining the character display device, FIG. 3 is an embodiment of the present invention, FIG. 4 is a waveform diagram in the embodiment of the present invention, FIG. 5 is an explanatory diagram of a conventional example, and FIG. 6 is an illustration of the present invention. Explanatory drawings of one embodiment of the invention are shown.

Claims (1)

[Claims] 1. In a character display device using a plasma display panel that performs display by a discharge spot of a discharge cell formed at the intersection of an X-direction electrode group and a Y-direction electrode group, and maintains the discharge display by a sustaining voltage, the above-mentioned discharge A display screen formed by a group of spots is divided into a character display area and an outside area, and a discharge maintaining voltage of intersection drive is supplied to the discharge spots forming inside the character display area, and an impedance is applied to the discharge spots forming outside the area. A plasma display panel characterized in that the plasma display panel is configured to supply a discharge sustaining voltage through the display panel, thereby applying an alternating voltage that rises slower than the sustaining voltage to a group of electrodes corresponding to an area other than the character display position. Driving method of character display device used.