KR20070005273A - Device which controls set-down voltage when it follows in change of temperature of plasma display panel - Google Patents

Abstract

A device for adjusting a set-down voltage according to the temperature variation of a plasma display panel(PDP) is provided to stably drive the PDP at a low temperature by changing the slope of a falling ramp wave according to the temperature of the PDP. A device for adjusting a set-down voltage according to the temperature variation of a plasma display panel includes a set-down voltage signal generator, a set-down voltage comparator(320), and a scan driver. The set-down voltage signal generator supplies a reset-down pulse to a first sustain electrode during a set-down of a reset period. The set-down voltage comparator detects the reset-down pulse voltage from the set-down signal generator, compares the reset-down pulse voltage with a predetermined reference voltage, and applies a scan driving control signal. The scan driver performs an address discharge in response to the scan driving control signal from the set-down voltage comparator. The set-down voltage comparator changes the slope of the falling ramp pulse according to the variation of the PDP.

Description

DEWICE WHICH CONTROLS SET-DOWN VOLTAGE WHEN IT FOLLOWS IN CHANGE OF TEMPERATURE OF PLASMA DISPLAY PANEL}

1 is a waveform diagram illustrating a driving waveform of a scan electrode Y among voltages for driving a conventional plasma display panel.

2 is a waveform diagram for explaining a driving waveform of the scan electrode Y to be changed by a temperature change among voltages for driving the plasma display panel according to the present invention;

3 is a circuit diagram of a set-down voltage comparison detection unit of a plasma display panel according to the present invention;

<Description of the symbols for the main parts of the drawings>

320: set-down voltage comparison detection unit 321: first resistance

322: second resistor 323: third resistor

324: Comparator 325: Transistor

The present invention relates to a plasma display panel, and more particularly, to a set-down voltage control apparatus according to a temperature change of a plasma display panel for stably driving by changing the set-down voltage according to a temperature change of the plasma display panel. will be.

1 illustrates a driving waveform of a scan electrode Y among voltages for driving a conventional plasma display panel.

As shown, the driving waveform of the scan electrode is a reset period for initializing the full screen of the plasma display panel, an address period for selecting a cell, and a sustain for maintaining the discharge of the selected cell. It is driven by periods.

The AC plasma display panel driving waveform is basically expressed as a "RESET" section for making the same condition before address discharge and a "SCAN" section for addressing image data to the selected scan line.

The reset section initializes all the cells of the plasma display panel. Initialization means to make all the wall charges generated in the previous discharge for the ON cell or the OFF cells in the same condition so that the subsequent discharge can proceed normally.

Since all cells are affected by the discharge in this section, light generation should be suppressed as much as possible in order to improve contrast.

In order to suppress light generation in the reset section, the most widely used method in the AC plasma display panel is a dark discharge reset using a voltage ramp.

The reset section is composed of a "set-up" section and a "set-down" section. In the set-up period, a voltage lamp was applied to the Y electrode and the X electrode and the Z electrode were kept at 0V. In the set-down period, down-ramp is applied to the Y electrode, Vs is applied to the Z electrode, and 0V is applied to the X electrode.

At the end of the set-down ramp, when the 0V to the X electrode, the Vs to the Z electrode, and the -Vy + ΔVy to the Y electrode were applied, the gap voltage between the YZ and XY electrodes was near the discharge start voltage. In addition, strong normal glow discharge can occur when a change in external voltage occurs in the direction of increasing the discharge space voltage from these voltages.

When ΔVy = 0, the voltage of the scan pulse is the same as the last voltage of the set-down ramp, so the X-Y discharge space voltage is near the discharge start voltage only by the scan pulse alone.

In case of? Vy> 0, the X-Y discharge space voltage due to the scan pulse alone is in the transition region where dark discharge and glow discharge can be generated, thereby further reducing Vd.

If DELTA Vy is too large, misdischarge may occur between the X-Y and Y-Z electrodes only by the scan pulse alone. Therefore, in the optimized waveform, DELTA Vy is set so as to be located in the middle region of the discharge between X-Y electrodes without generating an erroneous discharge between Y and Z.

The voltage setting of the scan section is a major factor influencing the high and low temperature characteristics of the plasma display panel.

In the reset period, the rising ramp waveform Ramp-up is simultaneously applied to all scan electrodes in the set-up period. The discharge occurs in the cells of the full screen by the rising ramp waveform. By the setup discharge, positive wall charges are accumulated on the address electrode and the common sustain electrode, and negative wall charges are accumulated on the scan electrode.

In the set-down period, after the rising ramp waveform is supplied, the falling ramp waveform Ramp-down falling at the positive voltage lower than the peak voltage of the rising ramp waveform is simultaneously applied to the scan electrodes.

The falling ramp waveform causes some of the overcharged wall charges by causing a slight erase discharge in the cells. By the set-down discharges, wall charges such that the address discharges can be stably generated remain uniformly in the cells.

In the address period, negative scan pulses are sequentially applied to the scan electrodes, and at the same time, positive data pulses are applied to the address electrodes in synchronization with the scan pulses.

As the voltage difference between the scan pulse and the data pulse and the wall voltage generated in the initialization period are added, an address discharge is generated in the cell to which the data pulse is applied.

In the cells selected by the address discharge, wall charges are formed such that a discharge can occur when a sustain voltage is applied. The common sustain electrode is supplied with a positive DC voltage during the set-down period and the address period.

The DC voltage causes set-down discharge between the common sustain electrode and the scan electrode in the set-down period, and address discharge generated between the scan electrode and the address electrode in the address period causes surface discharge between the scan electrode and the common sustain electrode. To transition to.

In the sustain period, sustain pulses sus are alternately applied to the scan electrodes and the common sustain electrodes. In the cell selected by the address discharge, the sustain voltage, that is, the display discharge, is generated between the scan electrode and the common sustain electrode every time the sustain pulse is applied as the wall voltage and the sustain pulse in the cell are added.

Finally, after the sustain discharge is completed, a ramp waveform (erase) having a small pulse width and a low voltage level is supplied to the common sustain electrode to erase wall charge remaining in the cells of the full screen.

However, the conventional plasma display panel has a problem that driving is unstable, such as discharge does not occur when operating in a low temperature environment. For example, an address discharge may not occur when scanning a plasma display panel in a low temperature environment.

If no address discharge occurs for the selected cell in this way, an image cannot be displayed because sustain discharge does not occur in the selected cell even if a sustain voltage is applied.

An object of the present invention for solving the above problems is to provide a set-down voltage control device according to the temperature change of the plasma display panel that can be stably operated at low temperatures.

The set-down voltage control apparatus according to the temperature change of the plasma display panel according to the present invention for solving the above problems, the set-down for supplying the reset-down pulse to the first sustain electrode during the set-down of the reset period A set-down voltage comparison detector for detecting a voltage of the reset-down pulse from the set-down signal generator and applying a scan driving control signal to a preset reference voltage; In the set-down voltage control device of the plasma display panel including a scan driver for performing an address discharge in response to the scan drive control signal from the comparison detection unit, the set-down voltage comparison detection unit, according to the change of temperature It is characterized by changing the slope of the waveform of the falling lamp.

The set-down voltage comparison detection unit receives a bit control signal of a temperature sensor and first and second resistors connected in series to divide a resistance component, and is higher than a negative scan voltage (-Vy) by a predetermined voltage (ΔV). A comparator for comparing a set-down voltage Vd divided by the first and second resistors with a temperature change, and a preset reference voltage Vr for performing an addressing operation by the scan driver; A switching unit connected in parallel with a second resistor and on / off according to a temperature signal to supply a reference voltage Vref to a common terminal of the first and second resistors to adjust the set-down voltage Vd. do.

Specific details of other embodiments are included in the detailed description and drawings.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view illustrating a driving waveform of the scan electrode Y to be changed by a temperature change among voltages for driving the plasma display panel according to the present invention.

As shown, in the reset period of the subfield SF in the selective write method, the scan / sustain electrode lines Y have a reset pulse RP of a ramp-up waveform followed by a reset pulse (-RP) of a ramp-down waveform. Are supplied sequentially.

The reset pulse (-RP) of this ramp-down does not fall to the negative scan reference voltage (-Vy), but rather to the set down voltage (Vrd) higher by ΔV than the negative scan reference voltage (-Vy). As a result, the positive wall voltage of the address electrode X by? V is less extinguished, and this wall charge amount makes it possible to discharge with a lower data voltage in the subsequent address discharge.

After that, when the reset pulse falls to the set-down voltage Vrd, the addressing operation is performed. For example, when the reset pulse falls to the setdown voltage Vrd in the normal operation until the reset period, the selective write scan pulse having the scan voltage is applied in the address period to perform the address discharge.

However, if the reset pulse falls to the setdown voltage Vrd earlier than the end of the reset period due to the external temperature or the driving condition, the scan voltage is maintained from that point instead of maintaining the setdown voltage Vrd during the reset period. The branch applies an optional write scan pulse to perform address discharge.

3 is a circuit diagram of a setdown voltage comparison detection unit of a plasma display panel according to the present invention.

As shown in the drawing, the set-down voltage comparison detector 320 of the present invention includes first and second resistors 321 and 322, a comparator 324, a third resistor 323 and a transistor for generating a reference voltage Vref. 325.

The first and second resistors 321 and 322 receive a bit control signal from a temperature sensor (not shown) to divide the voltage, and the comparator 324 compares two voltages input to the input side. Output high / low.

The external voltage source Vcc that can be used for the comparator 324 is about 15V, and can be connected to the ground terminal as a negative scan voltage source (-Vy).

Here, the external voltage source Vcc may be used because it is a voltage that is already designed for gate driving of the switch element in the plasma display panel.

The setdown voltage Vd and the reference voltage Vr to be detected are compared by the comparator 324. However, the set down voltage Vd is not directly applied to the comparator 324 because the set-down voltage Vd is directly applied to the plasma display panel because a reset-peak voltage and a sustain voltage of several hundred volts are applied. Therefore, the voltage is divided using the resistors 321 and 322, and the divided setdown voltage Vd is applied to the comparator.

Here, in using the resistors 321 and 322 for voltage dividing, it is possible to change the resistance value according to the temperature of the plasma display panel using a digital resistor that can be controlled digitally.

That is, the setdown voltage Vd is divided by the first resistor 321 according to the temperature, and the setdown voltage Vd is set as the reference voltage Vr regardless of the temperature, and the comparator 324 compares the actual setdown. The voltage Vd is changed. In this way, the set-down voltage Vd input to the comparator 324 has an operating range of 9 (V) <Vd <20 (V), and is compared by the reference voltage Vr.

The switching unit adjusts the setdown voltage Vd by supplying a reference voltage Vref to a common terminal of the first and second resistors 321 and 322. To this end, the switching unit includes a third resistor 323 and a switching transistor 325 connected in series.

That is, the third resistor 323 and the transistor 325 connected in parallel with the second resistor 322 are turned on / off according to the temperature signal and are referred to as a common terminal of the first and second resistors 321 and 322. The supply voltage Vref is supplied. In this case, the transistor 325 is turned on at a low temperature and turned off at a high temperature based on a specific temperature.

Accordingly, the signal output through the comparator 324 is changed from low or high to high or low, and then the addressing operation is performed by the scan driver. As described above, when the reset pulse is dropped to the setdown voltage Vrd higher by ΔV higher than the negative scan voltage −Vy by the setdown voltage comparison detector 320, the addressing operation is performed.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention described above may be modified in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the above-described embodiments are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the appended claims rather than the detailed description, and the meaning and scope of the claims and All changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

As described above, according to the set-down voltage control apparatus according to the temperature change of the plasma display panel according to the present invention, the plasma display panel can be operated stably even at low temperatures by changing the slope of the falling ramp waveform in accordance with the change in temperature. It is effective.

Claims (2)

A set-down signal generator for supplying a reset-down pulse to the first sustain electrode during the set-down of the reset period; and detecting a voltage of the reset-down pulse from the set-down signal generator and detecting a preset reference voltage. And a set-down voltage comparison detector for applying a scan driving control signal, and a scan driver for performing address discharge in response to the scan driving control signal from the set-down voltage comparison detecting unit. In the set-down voltage regulator, The set-down voltage comparison detection unit, The set-down voltage control device according to the temperature change of the plasma display panel, characterized in that for changing the slope of the waveform of the falling lamp in accordance with the change in temperature. The method of claim 1, The set-down voltage comparison detection unit, First and second resistors connected in series to receive the bit control signal of the temperature sensor and divide the resistance component; An addressing operation is performed by the scan driver and the set-down voltage Vd higher than the negative scan voltage (−Vy) by a predetermined voltage (ΔV) and divided by the first and second resistors according to a temperature change. A comparator for comparing a predetermined reference voltage Vr for A switching unit connected in parallel with the second resistor and turned on / off according to a temperature signal to supply a reference voltage Vref to a common terminal of the first and second resistors to adjust the set-down voltage Vd. ; Set-down voltage control apparatus according to the temperature change of the plasma display panel comprising a.

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