JPH04216591A - Driving method for plasma display panel - Google Patents

Abstract

PURPOSE:To reduce power consumption by stepwise varying the anode side power supply potential to the driving potential which is higher than the electric discharge initiation potential and to the electric discharge holding potential which is lower than the electric discharge initiation potential for every line period. CONSTITUTION:The anode side power supply potential Vy is normally kept at the discharge holding potential and is changed to the driving potential in a prescribed duration for every line period. When the anode side power supply potential Vy is at the driving potential, electrical discharges occur at the intersections of selected electrodes A1 to An and K1 to Km. Once the discharges occur, these discharges continue even though the anode side power supply potential Vy is lowered to the electrical discharge holding potential because electric charges are accumulated in the discharging space. Thus, the discharging current is limited because the anode side power supply potential Vy moves from the driving potential to the lower potential i.e., the discharge holding potential after the start of electrical discharges and the transition of the electrical discharges to arc discharges is prevented without electric current limiting resistors.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a DC type plasma display panel.

DC-type plasma display panels (PDPs), which perform display by applying a DC voltage, have a simpler structure and drive control than AC (alternating current drive) type PDPs, and have the advantage of being able to modulate the number of drive pulses. It has the advantage of being able to display gradation based on the gradation.

[0003] Furthermore, by applying a bias voltage lower than the discharge starting voltage between the anode electrode and the cathode electrode, it is possible to lower the withstand voltage of the switching element (driver element) that controls the conduction between the discharge power source and the electrode. This makes it possible to reduce the price of PDPs.

0004

[Prior Art] Generally, in a matrix display type PDP that displays characters and figures by a combination of emitting dots (pixels), a plurality of X electrodes extending in the horizontal direction (line direction) and a plurality of Y electrodes extending in the vertical direction are used. Of these, the X electrode and Y electrode corresponding to the display dot are selected, and a voltage for discharge is applied.

In a DC type PDP, for example, the Y electrode is used as an anode electrode, and the X electrode is used as a cathode electrode. Then, a discharge occurs at the intersection (discharge cell) between the anode electrode and the cathode electrode to which a DC pulse voltage is selectively applied. One discharge cell corresponds to a dot.

FIG. 4 is a voltage waveform diagram showing a basic driving method of a DC type PDP.

At all times, that is, when no display is performed, the potential of the Y electrode on the anode side is set to a bias potential vb1 of, for example, about 130 volts, and the potential of the X electrode on the cathode side is set to a bias potential vb2 of about 50 volts. . At this time, a bias voltage Vb of about 80 volts is applied to the discharge cell, but since the bias voltage Vb is lower than the discharge start voltage Vf, no discharge occurs.

During display, the potential of the anode electrode is set to a driving potential va of, for example, about 200 volts, and the potential of the cathode electrode is set to a ground potential (0 volts). As a result, a drive voltage Va exceeding the discharge start voltage Vf is applied to the discharge cell, causing a discharge.

Although FIG. 4 shows how one dot is driven, in general, when displaying a matrix on a PDP, line sequential (line sequential) display is performed line by line by selecting the X electrodes one by one. drive control is performed.

FIG. 5 is a diagram showing an example of matrix display using the line sequential method.

In the example of FIG. 5, as shown in FIG. 5(a), among the m X electrodes x1 to xm, X electrodes x1 to x5,
In a matrix made up of Y electrodes y1 to y5 among n Y electrodes y1 to yn, the letter "M" is displayed by causing discharge cells to emit light as shown by white circles in the figure.

Referring also to FIG. 4, first, as shown in FIG. 5(b), the first line X electrode (degree) is set to the ground potential. At the same time, Y
The potentials of the electrodes y1 and y5 are set as a drive potential va. As a result, light emission occurs due to discharge in the two discharge cells defined at the intersection of the X electrode x1 and the Y electrodes y1 and y5, and the light emission continues during the line period T1.

After the line period T1 has elapsed, the display moves to the second line, and the potential of the X electrode x1 is the bias potential v in the steady state.
b2, and instead set the X electrode x2 to the ground potential. At the same time, Y electrodes y1 and y5 are successively selected from the first line, and Y electrodes y2 and y4 are newly selected,
Let each potential be a drive potential va. This results in 4
Light emission occurs in each discharge cell.

[0014] From now on, for every line period T1, 3
X electrode x3, x corresponding to the display of the 5th line to the 5th line
4 and x5 in sequence and, in parallel, select a predetermined Y electrode to cause a predetermined discharge cell to emit light. Then, when the display of the mth line is completed, the display of the first line is performed again, and the display of the 1st to mth lines (1 field) is repeated.

Now, in a DC type PDP, the respective potentials of the anode electrode and the cathode electrode are controlled by a driver circuit consisting of a switching element.

FIG. 6 shows a conventional anode driver circuit 20j.
FIG. 7 is a timing chart showing the operation of the anode driver circuit 20j of FIG. 6. FIG.

In FIG. 6, an anode driver circuit 20
j is composed of switching transistors Q1 and Q2, and a current limiting resistor R1 having a resistance value of about 100 kilohms to 1 megohms, one of which is provided on each of the anode electrodes.

The collector of transistor Q1 is connected to power supply line Vy, and the collector of transistor Q2 is connected to bias line VB1. The potential of the power supply line Vy is a drive potential va, and the potential of the bias line VB1 is a bias potential vb1, and both of these potentials are kept constant.

At each base of transistors Q1 and Q2,
Drive pulse signals S1 and S2 having mutually opposite phases are applied from respective drive logic circuits (not shown).

Current limiting resistor R1 includes transistors Q1,
The emitters of Q2 are provided between the commonly connected connection point P1 and the anode electrode.

Note that instead of the transistor Q2, a pull-down resistor may be used to connect the bias power supply line VB1 and the connection point P1.

Referring also to FIG. 7, drive pulse signal S1 is normally at a low level, and transistor Q1 is in an off state. Conversely, the drive pulse signal S2 is at a high level, and the transistor Q2 is turned on. At this time, the potential of the connection point P2 (ie, the anode electrode) becomes the bias potential vb1.

When selecting an anode electrode for display, the logic levels of drive pulse signals S1 and S2 are inverted, and transistor Q1 is turned on instead of transistor Q2.

By turning on the transistor Q1, the connection point P
The potential of 1 is the drive potential v, as shown by the dashed line in FIG.
Stand up on a. However, the anode electrode (connection point P2)
As shown by the solid line in FIG. 7, the potential increases according to a time constant determined by the capacitance of the discharge cell and the resistance value of the current limiting resistor R1.

The potential of the anode electrode is the discharge starting potential vf
When the potential difference with the cathode electrode reaches the discharge starting voltage Vf, a discharge occurs in the discharge cell. Then, as the voltage of the current limiting resistor R1 decreases due to the discharge current, the potential of the anode electrode decreases to the discharge sustaining potential vs, thereby stabilizing the discharge. Thereafter, the discharge continues for a period in which the transistor Q1 is in the on state (for example, one line period T1).

[0026]

As described above, in the conventional driving method, the driving voltage Va is applied to the anode electrode via the current limiting resistor R1 in order to stabilize the discharge.

That is, in order to display one dot, the transistor Q1 is turned on for at least one line period T1, and a discharge current is supplied to the anode electrode. At this time, if the current limiting resistor R1 is omitted, the discharge will shift from glow discharge to arc discharge within the line period T1, and the discharge cell will be destroyed.

Therefore, conventionally, by providing the current limiting resistor R1, the electric power obtained by multiplying the discharge current by the voltage corresponding to the potential difference between the anode electrode potential va and the discharge sustaining potential vs is controlled by the current limiting resistor R1. Therefore, there was a problem in that the power consumption of the PDP was large.

Furthermore, since the current limiting resistor R1 is provided for each of the large number of anode electrodes, there is a problem in that the number of steps required to assemble the PDP drive circuit board is large.

Furthermore, since the time constant determined by the capacitance of the discharge cell and the current limiting resistor R1 is large, as shown in FIG. There is also the problem that the discharge delay time Tn becomes long, which is disadvantageous in performing gradation display.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to reduce power consumption, simplify assembly of a PDP, and facilitate multi-gradation display.

[0032]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the driving method according to the present invention provides a plurality of electrodes A1 to An, K arranged oppositely in a grid pattern, as shown in FIGS. 1 to 3.
A method of driving a plasma display panel 1 in which a DC pulse voltage is selectively applied to a line period T to Km to perform matrix display in a line sequential manner.
1, the potential of the anode side power supply Vy is changed to the discharge starting potential vf
The voltage is shifted stepwise to a higher drive potential va and a discharge sustaining potential vs lower than the discharge start potential vf.

[0033]

[Function] When displaying, the electrodes A1 to A1 every line period T1
An, K1 to Km are selected, and a discharge current is supplied from the anode side power supply Vy to the selected one of the electrodes A1 to An.

The potential of the anode side power supply Vy is normally set to the discharge sustaining potential vs, and is set to the drive potential va for a predetermined time every line period T1.

The potential of the anode side power supply Vy is the drive potential va
At this time, discharge occurs at the intersections of the selected electrodes A1 to An and K1 to Km. Once a discharge occurs, charge is accumulated in the discharge space, so the discharge continues even if the potential of the anode side power supply Vy drops to the discharge sustaining potential vs.

That is, after the start of discharge, the anode side power supply Vy
The discharge current is limited by lowering the potential from the drive potential va to the discharge sustaining potential vs, and the transition to arc discharge is prevented even without a current limiting resistor.

[0037]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a plan view showing the electrode structure of the PDP 1 according to the present invention.

The PDP 1 has a plurality of parallel cathode electrodes K1 to Km extending in the horizontal direction and a plurality of anode electrodes A1 to An extending in the vertical direction and parallel to each other. The cathode electrodes K1 to Km and the anode electrodes A1 to An are arranged to face each other with a discharge space interposed therebetween, and a discharge cell (not shown) is defined at each intersection of these electrodes.

The cathode electrodes K1 to Km are so-called scan-side electrodes that are sequentially selected one by one in each line period T1 as explained in FIG. 5 in the matrix display using the line sequential method. The drive is controlled by a cathode driver circuit 10.

On the other hand, the anode electrodes A1 to An are
These electrodes are so-called data-side electrodes that are selected based on display data, and are driven and controlled by anode-side drive units 22 that each include an anode driver circuit 20 and one power supply control unit 21.

FIG. 1 is a timing chart showing the driving method of the present invention. Further, FIG. 2 is a circuit diagram showing a main part of the anode side drive section 22 according to the drive method of the present invention.

In FIG. 2, components having the same functions as those in FIG. 6 are designated by the same reference numerals.

In the anode side drive section 22, the anode driver circuit 20 includes transistors Q1 and Q2 connected in series between the power supply line Vy and the bias line VB1.
It consists of That is, the anode driver circuit 20 is not provided with the conventional current limiting resistor R1 (see FIG. 6), and the connection point P1 and each of the anode electrodes A1 to A
n (anode electrode A1 in the figure) are directly electrically connected.

Power supply line Vy and bias line VB1
is a common line to which each anode driver circuit 20 is commonly connected.

Bias line VB1 is maintained at a constant bias potential vb1 as in the conventional case. On the other hand, the potential of the power supply line Vy is shifted stepwise by the power supply control unit 21 to the drive potential va and the discharge sustaining potential vs.

The power supply control section 21 is composed of switching transistors Q3 and Q4.

The collector of one transistor Q3 is connected to the main power supply V kept at the drive potential va, and the collector of the other transistor Q4 is connected to the sub power supply V2 kept at the discharge sustaining potential vs.

The power supply line Vy for supplying discharge current to each anode driver circuit 20 is connected to transistors Q3,
The emitters of Q4 are connected to a commonly connected connection point P3.

Each of the transistors Q3 and Q4 performs a switching operation in response to control pulse signals S3 and S4 having opposite phases to each other and applied to their respective bases from a drive logic circuit (not shown).

Next, the driving method of the present invention will be explained with reference to FIG.

For display, as described above, the timing t is used to select the anode electrodes A1 to An on the data side in synchronization with the selection of the cathode electrodes K1 to Km on the scan side, that is, the timing t when the transistor Q1 is turned on.
1, the control pulse signal S3 is set to high level for a short time T2 of, for example, about 1 μs, and the transistor Q3 is turned on.

As a result, the power supply line Vy becomes the drive potential va of the main power supply V, and the potential of the anode electrode A1 directly connected to the connection point P1 also rises to the drive potential va almost simultaneously. As a result, a drive voltage Va exceeding the discharge start voltage Vf is applied to the discharge cell, causing a discharge. Space charges are accumulated in the discharge space that enable the discharge to be sustained by the discharge sustaining voltage Vs.

After the elapse of time T2, the control pulse signals S3,
The logic level of S4 is inverted, transistor Q4 is turned on instead of transistor Q3, and power supply line Vy is set to discharge sustaining potential vs. At this time, the transistor Q1 of the anode driver circuit 20 continues to be in the on state, and stable discharge by the discharge sustaining voltage Vs continues in the discharge cell.

That is, by lowering the voltage applied to the discharge cell from the drive voltage Va to the discharge sustaining voltage Vs, the discharge current becomes appropriate, and the discharge continues while transition to arc discharge is suppressed.

The switching operation of the power supply control section 21 as described above is repeated every line period T1. Therefore, the potential of the power supply line Vy is the same as that of the cathode electrodes K1 to Km
In synchronization with the selection of , the driving potential va and the discharge sustaining potential vs are shifted stepwise.

On the other hand, in the anode driver circuit 20,
When the display of the discharge cell corresponding to the anode electrode A1 is finished, as described above, the transistor Q2 is turned on instead of the transistor Q1, and the potential of the anode electrode A1 is returned to the normal bias potential vb1.

According to the embodiment described above, by providing one power supply control section 21, each anode electrode A1 to An
Since the current limiting resistor corresponding to can be omitted,
The PDP 1 can be assembled with fewer man-hours.

In the embodiments described above, the drive potential va, the discharge sustaining potential vs, and the time T2 can be changed as appropriate depending on the discharge characteristics determined by the discharge gap, the composition of the discharge gas, and the like. However, the drive potential va needs to be set to a value equal to or higher than the discharge start potential vf.

Furthermore, the circuit configuration of the anode side drive section 22 can be modified in various ways.

[0061]

According to the present invention, the current limiting resistor that was conventionally provided at each anode electrode is no longer necessary.

Therefore, the power consumption of the plasma display panel can be reduced by the amount of power consumed by the current limiting resistor.

Furthermore, the discharge delay time is shortened and multi-gradation display becomes easy.

Furthermore, the number of steps required to assemble the plasma display panel can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a timing chart showing a driving method of the present invention.

FIG. 2 is a circuit diagram showing main parts of an anode side drive section according to the drive method of the present invention.

FIG. 3 is a plan view showing the electrode structure of the PDP according to the present invention.

FIG. 4 is a voltage waveform diagram showing a basic driving method of a DC type PDP.

FIG. 5 is a diagram showing an example of a matrix display using a line sequential method.

FIG. 6 is a circuit diagram showing the configuration of a conventional anode driver circuit.

7 is a timing chart showing the operation of the anode driver circuit of FIG. 6. FIG.

[Explanation of symbols]

1 PDP (plasma display panel) A1-A
n Anode electrode (electrode) K1 to Km Cathode electrode (electrode) T1 Line period Vy Power supply line (anode side power supply) va Drive potential vf Discharge starting potential vs Discharge sustaining potential

Claims (1)

[Claims] Claim 1: A plurality of electrodes (
A method for driving a plasma display panel (1) in which a DC pulse voltage is selectively applied to A1 to An) (K1 to Km) so as to perform matrix display in a line sequential manner, the method comprising: , anode side power supply (
Vy) is set to a driving potential (Vy) higher than the discharge starting potential (vf).
va) and a discharge sustaining potential (vs) lower than the discharge starting potential (vf).