JPS5817959B2 - plasma display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reading coordinates of a plasma display.

Plasma displays are made by covering electrodes with a dielectric layer and placing them facing each other, filling a discharge gas such as Ne between them, and applying a voltage higher than the discharge starting voltage between the facing electrodes to create a discharge spot. Display is performed using a combination of discharge spots.

Generally, the alternating sustaining voltage v with equal positive and negative peak values between the electrodes
s is applied, and a write pulse voltage Vw is applied either superimposed on this sustaining voltage Vs or alone so that the peak value exceeds the discharge voltage VF to generate a discharge spot, and this discharge spot is temporarily stopped. Then, charges of the polarity of the applied voltage are accumulated in the dielectric layer, and a wall voltage VQ is generated, and the potential difference between this wall voltage VQ and the sustaining voltage Vs that is subsequently applied after half a cycle exceeds the discharge voltage VF. As a result, a discharge spot is generated again, and the resulting wall voltage VQ becomes opposite in polarity to the previous one.

Once a discharge spot is generated in this manner, a discharge spot is generated each time the polarity of the sustaining voltage vs is reversed, so that the discharge spot appears to be occurring continuously.

That is, by applying a sustaining voltage vs lower than the discharge voltage vF, the written information can be stored and displayed.

Furthermore, when a narrow pulse voltage or an erase pulse voltage slightly lower than the minimum sustaining voltage V s in is applied, a discharge spot is generated once, but the wall voltage vQ is not formed, and therefore the sustaining voltage vs No discharge spots will be generated even if the current is applied.

In other words, the display has been erased.

In addition, the wall voltage level is maintained at one of two levels, positive and negative, by using two groups of maintaining voltages with different positive and negative peak values, thereby facilitating display and memorization operations, and further enabling cursor display, etc. has been proposed, which is characterized by easy writing and erasing.

When a plasma display like the one described above is used as a computer display, the display information can be read or written by indicating the display screen position with a light pen, etc., in the same way as a conventional cathode ray tube (CRT) display. is required and the sustaining voltage Vs has a symmetrical waveform in positive and negative directions, the ignition cell is read out as shown in FIG.

That is, if the sustaining voltage applied to the non-selected cells has the waveform shown in FIG. 1a, a discharge spot will occur as shown in FIG. 1 each time the polarity changes.

Therefore, when a read pulse Pr is applied to the selected cell as shown in FIG. 1C, the timing at which a discharge spot is generated becomes as shown in FIG. 1D.

By strobing the detection output of the light pen with the strobe pulse shown in FIG. 1e at the timing at which a discharge spot is generated by this readout pulse Pr, the ignition cell can be read out.

For reading out non-ignition cells, if the sustaining voltage applied to the non-selected cells is as shown in FIG. 2a, the read pulse Pr is
As shown in FIG. 2C, following the sustain voltage, a set of a pulse of the same polarity and a large peak value and a pulse of the opposite polarity and a low peak value is applied to the selected cell.

If the non-selected cell is in the ignition state, a discharge spot is generated at the timing shown in FIG. 2 due to the sustaining voltage shown in FIG. 2a, and even if the read pulse Pr is applied as shown in FIG. , if the selected cell is in the ignition state, the discharge spot is as shown in FIG. 2d, which is the same as the timing shown in FIG.

However, if the selected cell is in the non-ignition state, the read pulse Pr
Accordingly, a discharge spot is generated at the timing shown in FIG. 2e.

When the light pen detects this discharge spot, it can be strobed with the strobe pulse shown in FIG. 2f to read out non-fired cells.

The readout method described above has the disadvantage that the readout pulses for ignited cells and non-ignited cells have different peak values, and the voltage margin for non-destructive reading is small, making it difficult to perform stable operation. be.

The present invention is a novel invention that improves the above-mentioned drawbacks, and its purpose is to provide a large read pulse voltage margin and stabilize the read operation.

Briefly stated, the coordinate readout method of the present invention consists of a pulse with a high 6 high value of one polarity and a pulse with a low peak value of the other polarity following the pulse, and the second sustaining voltage of the set of two pulses. and,
A second sustaining voltage consisting of a plurality of sets of two pulses, each consisting of a pulse with a high peak value of the other polarity and a pulse with a low peak value of one polarity following the pulse, is applied to the plasma at a predetermined period.・Apply to the electrodes of the display, and during the readout period, correspond to the wall voltage level of the discharge point between the opposing electrodes of the plasma display. or two pulses with one low peak value of one polarity or a pulse with one high peak value of one polarity and two pulses with one low peak value of the other polarity following the pulse, and the second sustaining voltage A photodetector detects a discharge spot caused by a pulse with a high peak value applied at a timing after a pulse with a high value and which is applied next to a pulse with a high peak value of the other polarity or a pulse with a low peak value applied next to a pulse with a high peak value of one polarity. It is characterized by detecting and reading out coordinates, and examples thereof will be described in detail below.

3 and 4 are operation explanations of the embodiment of the present invention; clear waveform diagrams, FIG. 3 shows reading when the wall voltage level in the initial state is positive, and FIG. 4 shows the wall voltage level in the initial state. This is for reading when the level is negative.

The first sustaining voltage vs has different positive and negative waveforms having a high wave peak value vH of one polarity and a low wave peak value -VL of the other polarity.

It consists of a set of pulses, and the second sustaining voltage Vs2 is the high wave peak value of the other polarity = VH and the low wave peak value of one polarity +v
It consists of a set of pulses having different positive and negative waveforms, each consisting of an arbitrary cycle.

Normally; the first sustaining voltage VSI and the second sustaining voltage Vs2 are applied to the electrodes without the pulse of v2 in the waveform shown in FIG. 3a, and the wall voltage level in the initial state is positive. Therefore, a discharge spot is generated at the timing shown in FIG.

Note that the application of these sustaining voltages is 1 in 16 unit cycles.
The cycle is configured such that the first
The second sustaining voltage is applied in each of the following 15 unit periods.

Therefore, in the former case where the initial wall voltage level is positive (the number of discharges is large), the panel is left in a bright state, and in the latter case where the initial wall voltage level is negative, the number of discharges is small and the panel is left in a dark state. .

In other words, according to this driving method, since weak discharge occurs even in the off state, ions are always present in the gas space, which has the advantage of making it easier to write addresses.

Now, to perform reading, as shown in FIG. 3a, a pulse V1 of -VH, a pulse v2 of 10 VL, and a pulse V3 of +VL are applied during the read period RP.

The timing of discharge spots due to each pulse during this read period RP is as shown in FIG. 3C.

In other words, the discharge spot that was generated at the timing of pulse V3 is now generated at the timing of pulse V2, and the detection output of a photodetector, such as a well-known light pen, is strobed with the strobe pulse shown in Figure 3d. coordinates can be read out.

Note that this is synonymous with taking the AND of the pulse v2 and the detection output of the photodetector.

If the wall voltage level in the initial state is negative, a discharge spot will occur at the timing shown in FIG.

The read pulse is applied at an appropriate period (period) of the second sustaining voltage vs2, as shown by the symbol RP in FIG.
It consists of a pulse V6 of L.

This readout pulse generates a discharge spot at the timing shown in Figure 4C, and the detection output of the light pen and the pulse v
The strobe shown in FIG. 4d corresponding to the timing of 5.
The coordinates can be read out by performing an AND with the pulse.

As is clear from Figures 3a and 4a,! The period of the second sustaining voltage vs2 is shifted by half a cycle so that a read pulse can be inserted.
In FIG. 4a, pulse V2 is not inserted, and in FIG. 4a, pulse V4. The phase of V6 is reversed, resulting in a J-state waveform in which pulse v5 is not inserted.

When reading out, when a discharge spot is generated by the second sustaining voltage Vs2, as shown in FIG. When a read pulse is applied and a discharge spot is generated at the first sustaining voltage VSI, as shown in FIG. The pulse V4. of the first sustaining voltage waveform is generated at the timing of one set of pulses V4. Substantially four read pulses having a waveform consisting of pulse V6 and pulse v5 inserted between them are applied.

Note that if flicker occurs on the display by shifting the second sustaining voltage VS2 by half a cycle, apply a sustaining voltage of the same period and apply the read pulse only to obtain the waveform as described above. It is also possible to configure a logic circuit.

As a readout method for a plasma display, a method has been proposed in which a readout pulse is applied in a point scanning manner, that is, to sequentially scan discharge cells one by one, and coordinates indicated by a photodetector, such as a light pen, are read out.

In this dot scanning readout method, when the display screen is large, the number of discharge cells is large, so the readout time is long.

In order to shorten this readout time, a split readout method has been proposed in which the display screen is divided into two, the area in which the designated coordinates are detected is detected, and the detected area is further divided into two and the detection is repeated. ing.

Although this divisional readout method shortens the readout time, it complicates the peripheral circuitry.

Therefore, a group scanning readout method has been proposed in which the peripheral circuitry is relatively simple and the readout time is relatively short.

This is a method in which the display screen is divided into a plurality of groups, and the groups are first scanned, and then the groups where the designated coordinates are present are scanned by points or lines.

The present invention can be applied to each of the above-mentioned systems, and FIG. 5 shows a block diagram when applied to the above-mentioned group scanning readout system.

Referring to FIG. 5, the coordinates of the plasma display PDP are indicated by a photodetector, such as a light pen LP.

The electronic computer CPU activates the sustain pulser STP from the control unit CU in response to a command, and outputs the first sustaining voltage VSI and the second sustaining voltage Vs2 (excluding pulse v2) as shown in FIG. 3a to the driver DV. , is applied to the electrodes on the entire surface of the plasma display FDP via the mixing gate MG.

Address data for writing or erasing from the computer CPU is transferred from the address register ADR to the decoder D.
E and C, decoded by the decoder DEC, and the control unit CU activates the ignition and erase pulser FEP according to the write or erase command, and its output is added to the driver DV at the desired timing with the maintenance voltage. Decoder I
) Writing or erasing is performed at an address specified by mixing gate MG in accordance with the output of EC.

That is, the wall voltage level is converted from the first state to the second state or vice versa.

Further, the read pulsers R and PS are activated by the read command, and their outputs are applied from the driver DV to the plasma display FDP via the mixing gate MG4.

This plasma display FDP is divided, for example, into four groups in each of the X and X directions, and assuming that one group consists of 32 lines of electrodes, the inhibit resistors IH, R,.

The lower 5 bits are inhibited, and the higher 2 bits are used to scan the four groups with read pulses.

In this case, the X, Y switching circuit XYSW first scans the group in the X direction, and a read pulse is applied to all lines in the group as shown in FIG. If a detection output is generated by the light pen LP when the group is scanned, the detection output is applied to the amplification and shaping circuit ASC, and its output signal is input to the inhibit register IHR, address counter AD.
C'1. .

Joins ADC2.

The address counter ADCI counts the upper 2 bits, and stops its counting in response to the output signal of the amplification/shaping circuit ASC and holds the current contents, and also counts the lower 5 bits of the inhibit register IHR. The prohibition is canceled and the address counter ADC2 starts counting the first five bits.

Therefore, the contents of the upper 2 bits of the address register ADH are the same as the contents of the address counter ADC1 which counts the upper 2 bits, and the address register ADH! Counter ADC2 counts according to the scan for 32 lines in the group corresponding to the contents of address counter ADC1.

When the detection output of the light pen LP is obtained by scanning the lines consisting of
The count of 2 is stopped.

Since the contents at that time indicate the designated position line within the group, the X coordinate is read out according to the contents of the address counters ADC1ADC2.

5. Based on the second detection output from the light pen LP.

The amplification and shaping circuit ASC sends a switching signal to the X, Y switching circuit XY8W, and then scans in the Y direction.

When this scanning in the Y direction is completed, the X/Y switching circuit xysw
An end signal END is sent from 4 to the phloem CU, and the transfer of coordinate information in the address register ADR is controlled.

As explained above, the present invention provides a first sustaining voltage of a set of two pulses: a pulse with a high wave peak value of one polarity +VH and a pulse with a low wave peak value -VL of the other polarity following the pulse. Vs, a second sustaining voltage v consisting of a plurality of sets of two pulses: a pulse with a high wave height fFX-VH of the other polarity and a pulse with a low wave height +vL of one polarity next to the pulse;
s2 are applied to the electrodes of the plasma display at predetermined intervals, and the readout pulse is applied to the other electrode in accordance with the wall voltage level of the discharge point between the opposing electrodes of the plasma display during the readout period. A pulse with a high peak value of one polarity and two low pulse peak values of one polarity following the pulse, or a pulse with a high peak value of one polarity and two low peak values of the other polarity following the pulse. A pulse is applied at a timing after the pulse with the low peak value of the second sustaining voltage, and is applied after the pulse with the high peak value of the other polarity or the pulse with the high peak value of one polarity. The coordinates are read out by detecting a discharge spot caused by a pulse with a low peak value.

Then, the wall voltage level is converged to a constant level by the last pulse constituting the read pulse, and the storage display state is not destroyed even if the read pulse is applied.

Furthermore, since the actual read pulse has a pulse waveform with a low peak value, there is no possibility that erroneous discharge will occur in non-selected cells adjacent to the selected cell due to the application of the pulse.

Therefore, the voltage margin is increased, and a stable read operation can be performed.

[Brief explanation of the drawing]

1 and 2 are waveform diagrams illustrating the operation of the coordinate reading method when a sustaining voltage with positive and negative peak values is applied, and FIGS. 3 and 4 are waveform diagrams illustrating the operation of the embodiment of the present invention. FIG. 5 is a block diagram in which the plasma display coordinate readout method of the present invention is applied to a group scanning readout method. vsl is the first sustaining voltage, VS2 is the second sustaining voltage, R
, P is the read period.

Claims (1)

[Claims] 1. The first sustaining voltage of a set of two pulses: a pulse with a high peak value of one polarity and a pulse with a low peak value of the other polarity following the pulse, a pulse with a high peak value of the other polarity, and a pulse with a high peak value of the other polarity. Next to the pulse, a pulse with a low peak value of one polarity and a second sustaining voltage consisting of a plurality of sets of two pulses are applied to the electrodes of the plasma display at a predetermined period, respectively, and a readout period is set. In response to the wall voltage level at the discharge point between the opposing electrodes of the plasma display, a pulse with a high peak value of the other polarity and two pulses with a low peak value of one polarity following the pulse, or A pulse with a high peak value of one polarity and two pulses with a low peak value of the other polarity following the pulse are applied at a timing after the pulse with the low peak value of the second sustaining voltage. and a photodetector detects a discharge spot generated by a pulse with a low wave height value applied next to the pulse with a high wave height value of the other polarity or the pulse with a high wave height value of one polarity, and reads out the coordinates. Coordinate readout method for plasma displays.