KR20080040141A - Plasma display device - Google Patents

Abstract

A plasma display apparatus is provided to prevent distortion like overshoot or undershoot, by connecting a clamping unit between a sustain discharge voltage supplier and a panel capacitor electrically. A plasma display apparatus includes a plasma display panel having a panel capacitor between first and second electrodes and a driver for providing first and second voltages to the first and second electrodes. The driver includes an electric power recovery unit(510), a sustain discharge voltage supplier(520), and a clamping unit(530). The electric power recovery unit charges and discharges the panel capacitor. The sustain discharge voltage supplier which is connected between the electric power recovery unit and the panel capacitor, applies the first or second voltages to the panel capacitor and maintains the applied voltages. The clamping unit, which is connected between the sustain discharge voltage supplier and panel capacitor, maintains the voltage of the panel capacitor between first and second voltages.

Description

Plasma display device {PLASMA DISPLAY DEVICE}

1 is a view showing a conventional power recovery circuit.

FIG. 2 is a diagram schematically showing a sustain discharge pulse applied to the sustain electrode in the sustain period by the power recovery circuit shown in FIG.

3 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention.

4 is a circuit diagram of a sustain electrode driver according to an exemplary embodiment of the present invention.

5 is a diagram illustrating driving timing of a circuit of the sustain electrode driver illustrated in FIG. 4.

6A to 6D are diagrams showing current paths of respective modes in the circuit of the sustain electrode driver shown in FIG. 4.

The present invention relates to a plasma display device.

Plasma display devices are flat display devices that display characters or images using plasma generated by gas discharge, and dozens to millions or more of discharge cells are arranged in a matrix form according to their size.

The driving method of the plasma display device includes a reset period, an addressing period, and a sustain period, which is expressed as a change in time. The reset period is a period for initializing the state of each cell in order to smoothly perform an addressing operation on the cell. The address period is an address voltage for a cell (addressed cell) that is turned on to select a cell that is turned on and a cell that is not turned on. It is a period of time to apply an operation to accumulate wall charges. The sustain period is a period in which a discharge for actually displaying an image in the addressed cells by applying a sustain discharge pulse is performed.

In general, in the sustain period of the plasma display device, a sustain discharge pulse having a high level voltage and a low level voltage alternately applied to the scan electrode and the sustain electrode is applied with the opposite polarity to cause sustain discharge in the discharge cell. In this case, the capacitive component formed by the sustain electrode and the scan electrode may be modeled as a panel capacitor. In order to recover the reactive power generated when the panel capacitor is charged and discharged, the panel capacitor is charged and discharged by using LC resonance between the inductor of the power recovery circuit and the panel capacitor.

1 is a view showing a conventional power recovery circuit. 2 is a diagram briefly showing a sustain discharge pulse applied to the sustain electrode in the sustain period by the power recovery circuit shown in FIG.

As shown in FIG. 1, the power recovery circuit charges a current from the power recovery capacitor Cxerc to the panel capacitor Cp and a current from the panel capacitor Cp to the power recovery capacitor Cxerc. Discharge paths are formed, and sustain discharge paths including sustain discharge switching elements S3 and S4 are formed. At this time, the sustain electrode X is charged through the path of the switching element S1, the diode D1, and the inductor L, and is discharged through the inductor L, the diode D2, and the switching element S1.

However, when the sustain discharge pulse is applied to the sustain electrode X of the panel capacitor Cp by the operation of the sustain discharge switching elements S3 and S4, an overshoot is performed along the lines of the sustain electrodes as shown in FIG. 2. ) Or waveform distortion such as undershoot may occur. As such, when an overshoot or undershoot occurs when the sustain discharge pulse is applied, the voltage at the start point of the sustain discharge becomes different according to each discharge cell, resulting in a problem that the luminance of each discharge cell is not the same.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device for performing stable sustain period by preventing waveform distortion such as overshoot or undershoot when a sustain discharge pulse is applied.

According to a feature of the present invention for achieving the above technical problem is provided a plasma display device. The plasma display device includes a first electrode and a second electrode, the plasma display panel having a panel capacitor formed between the first and second electrodes and the first and second electrodes in the sustain period of each subfield. And a driver for applying a sustain discharge pulse alternately having one voltage and a second voltage lower than the first voltage. The driving unit may include a power recovery unit that charges and discharges the panel capacitor for a predetermined time, and is electrically connected between the power recovery unit and the panel capacitor to apply the first voltage or the second voltage to the panel capacitor. A sustain discharge voltage supply for maintaining time and an electrical connection between the sustain discharge voltage supply and the panel capacitor to maintain the voltage of the panel capacitor no higher than the first voltage and not lower than the second voltage. And a clamping portion for holding.

In this case, the clamping unit is electrically connected between the first clamping diode electrically connected between the first power supply for supplying the first voltage and the first electrode, and the second power supply for supplying the second voltage and the first electrode. It is preferred to include a second clamping diode to be.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to be "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, it means that it can include other components rather than excluding other components unless specifically stated otherwise.

Now, a plasma display device and a driving method according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, a schematic structure of a plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 3.

3 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention.

The plasma display device according to an exemplary embodiment of the present invention includes a plasma display panel 100, a controller 200, an address electrode driver 300, a scan electrode driver 400, and a sustain electrode driver 500.

The plasma display panel 100 includes a plurality of address electrodes A1-Am extending in the column direction, a plurality of sustain electrodes X1-Xn extending in the row direction, and a plurality of scan electrodes Y1-Yn. The plurality of scan electrodes Y1-Yn and the sustain electrodes X1-Xn are arranged in pairs with each other. The discharge cells are formed by the adjacent scan electrodes, the sustain electrodes, and the address electrodes crossing them.

The controller 200 receives an image signal from the outside and outputs an address electrode driving control signal, a sustain electrode driving control signal, and a scan electrode driving control signal. The controller 200 divides and drives one frame into a plurality of subfields, and each subfield includes a reset period, an address period, and a sustain period when expressed as a temporal change in operation.

The address electrode driver 300 receives an address electrode driving control signal from the controller 200 and applies a display data signal for selecting a discharge cell to be displayed to each address electrode.

The scan electrode driver 400 receives a scan electrode driving control signal from the controller 200 and applies a driving voltage to the scan electrode.

The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200 and applies a driving voltage to the sustain electrode.

Hereinafter, the structure and operation of the sustain electrode driver according to the exemplary embodiment of the present invention will be described in detail with reference to FIGS. 4 to 6D.

4 is a circuit diagram of a sustain electrode driver according to an exemplary embodiment of the present invention.

As shown in FIG. 4, the sustain electrode driver 500 according to an exemplary embodiment of the present invention includes a power recovery unit 510, a sustain discharge voltage supply unit 520, and a clamping unit 530. In FIG. 4, the switching elements S1, S2, S3, and S4 are denoted as n-channel MOSFETs, and each switching element may include a body diode. In addition, the switching elements S1, S2, S3, S4 may be composed of other switching elements having the same or similar function.

In addition, the panel capacitor Cp equivalently represents the capacitive component between the sustain electrode X and the scan electrode Y. FIG. In this case, the sustain electrode X of the panel capacitor Cp is connected to the sustain electrode driver 500, and the scan electrode Y of the panel capacitor Cp is the scan electrode driver 400 (“Y driver” in FIG. 4). Shown) is connected. Here, since the scan electrode driver 400 operates in the same manner as the sustain electrode driver 500, only the operation of the sustain electrode driver 500 will be described in the embodiment of the present invention for convenience of description.

The power recovery unit 510 of the sustain electrode driver 500 includes a power recovery capacitor Cxerc, an inductor L, a switching element S1 forming a charge path, a diode D1, and a switching element forming a discharge path. (S2) and diode D2. At this time, one end of the power recovery capacitor Cxerc is electrically connected between the drain of the switching element S1 and the source of the switching element S2. In addition, one end of the inductor L is electrically connected to the sustain electrode X of the panel capacitor Cp, and the other end of the inductor L is connected in series with the source of the switching element S1 and the diode D3. The drain of the switching element S1 and the diode D1 are electrically connected to each other. Here, the diode D1 is for setting the rising path for increasing the voltage of the panel capacitor Cp when the switching element S1 has a body diode, and the diode D2 is for the switching element S2 having the body diode. In this case, the fall path for setting the panel capacitor Cp to fall is performed. In this case, if the switching elements S1 and S2 do not have a body diode, the diodes D1 and D2 may be removed. The connected power recovery unit 510 connects the voltage of the sustain electrode X to Vs. It charges to voltage or discharges to ground voltage (typically 0V).

The sustain discharge voltage supply unit 520 is connected to a switching element S3 connected to a power supply terminal Vs for supplying a high level voltage Vs, and a switching element connected to a ground terminal GND for supplying a low level voltage 0V. (S4) is included. At this time, the sustain electrode X of the panel capacitor Cp is connected in series to the contact between the diodes D1 and D2 of the power recovery unit 510 and the switching elements S3 and S4 of the sustain discharge voltage supply unit 520. Connected. The switching element S3 is connected between the power supply terminal Vs supplying the high level voltage Vs and the sustain electrode X of the panel capacitor Cp, and the switching element S4 is connected to the low level voltage 0V. It is connected between the ground terminal (GND) for supplying the sustain electrode (X) of the panel capacitor (Cp).

The clamping unit 530 includes clamping diodes D3 and D4 for clamping the panel capacitor Cp so that an overvoltage is not applied to the panel capacitor Cp. At this time, the anode of the clamping diode D3 is connected between the switching element S3 and the sustain electrode X of the panel capacitor Cp, and the cathode is connected to the power supply terminal Vs. At this time, the clamping diode D3 clamps the voltage applied to the panel capacitor Cp by the overshoot so as not to rise above the high level voltage Vs. Meanwhile, the cathode of the clamping diode D4 is connected between the switching element S4 and the sustain electrode X of the panel capacitor Cp, and the anode is connected to the ground terminal GND. At this time, the clamping diode D4 clamps the voltage of the panel capacitor Cp so as not to fall below the low level voltage (0V) by an undershoot or the like.

Next, a time series operation change in the sustain period of the sustain electrode driver according to the exemplary embodiment of the present invention will be described with reference to FIG. 5. Here, the operation change is sequential in four modes M1 to M4, and the mode change is caused by the operation of the switching element. The phenomenon referred to herein as resonance is not a continuous oscillation but a change in voltage and current caused by the inductor L and the panel capacitor Cp generated when the switching elements S1 and S2 are turned on.

5 is a diagram illustrating driving timing of the sustain electrode driver circuit shown in FIG. 4, and FIGS. 6A to 6D are diagrams showing current paths of respective modes in the sustain electrode driver circuit illustrated in FIG. 4.

5 illustrates a waveform diagram of the sustain electrode voltage Vx and the current I _L of the inductor according to the driving timing of the sustain electrode driver circuit. Further, it is assumed that the voltage Vs / 2 is charged in the capacitor Cxerc before the mode 1 M1 shown in FIG. 6A starts.

(1) Mode 1 (M1)-see FIG. 6A

In the mode 1 section, the switching device S1 is turned on. Then, as illustrated in FIG. 6A, a current path ① is formed of the capacitor Cxerc, the switching element S1, the diode D1, the inductor L, and the panel capacitor Cp, thereby inducting the inductor L and the panel. Resonance occurs between the capacitors Cp. By this resonance, the panel capacitor Cp is charged, and as shown in FIG. 5, the sustain electrode voltage Vx of the panel capacitor Cp gradually increases from 0V to a voltage close to the Vs voltage. In addition, as shown in FIG. 5, the current I _L flowing in the inductor L increases linearly with a slope of V / L and decreases linearly with a slope of-(Vs-V) / L. .

(2) Mode 2 (M2)-see FIG. 6B

In the mode 2 section, when the current I _L flowing in the inductor L decreases to 0A, the switching element S1 is turned off. The switching element S3 is turned on to form a current path ② through the power supply terminal Vs, the switching element S1, and the panel capacitor Cp, so that the voltage Vx of the sustain electrode X is Maintained at Vs voltage.

Meanwhile, as shown in FIG. 2, overshoot may occur when the high level voltage Vs is applied to the sustain electrode X in the sustain period. Therefore, in the exemplary embodiment of the present invention, the clamping unit 530 is positioned between the sustain discharge voltage supply unit 520 and the panel capacitor Cp. That is, when an overshoot occurs when the switching element S3 is turned on and an overvoltage higher than the high level voltage Vs is applied to the panel capacitor Cp, the clamping diode D3 of the clamping unit 530 is turned on. . Then, as illustrated in FIG. 6B, the overvoltage is clamped through the path ③ of the panel capacitor Cp, the clamping diode D3, and the power supply terminal Vs.

(3) Mode 3 (M3)-see FIG. 6C

In the mode 3 section, the switching device S3 is turned off and the switching device S2 is turned on. Then, as illustrated in FIG. 6C, a current path ④ is formed of the panel capacitor Cp, the inductor L, the switching element S2, and the capacitor Cxerc to form a gap between the inductor L and the panel capacitor Cp. Resonance occurs at By this resonance, the sustain electrode voltage Vx of the panel capacitor Cp gradually decreases to 0V. That is, the panel capacitor Cp is discharged. In addition, as shown in FIG. 5, the current I _L flowing in the inductor L in the mode 3 section decreases linearly with the slope − (Vs−V) / L and increases with the slope of V / L. .

(4) Mode 4 (M4)-see FIG. 6D

When the current I _L flowing in the inductor L becomes 0A after the mode 3, the switching device S2 is turned off and the switching device S4 is turned on in the mode 4 section. Then, a current path ⑤ is formed through the panel capacitor Cp, the switching element S4, and the ground terminal GND, so that the voltage Vx of the sustain electrode is maintained at 0V.

Meanwhile, as shown in FIG. 2, undershoot may occur when the low level voltage (0V) is applied to the sustain electrode in the sustain period as shown in FIG. 6D. Therefore, in the exemplary embodiment of the present invention, the clamping unit 530 is positioned between the sustain discharge voltage supply unit 520 and the panel capacitor Cp. That is, when an undershoot occurs when the switching element S4 is turned on and a voltage below the low level voltage (0V) is applied to the panel capacitor Cp, the clamping diode D4 of the clamping unit 530 is turned on. do. Then, as shown in FIG. 6D, a voltage of less than 0V is clamped through the path ⑥ of the ground terminal GND-clamping diode D4-panel capacitor Cp.

After the mode 4 ends, the operation of the modes 1 to 4 is repeated in the scan electrode driver.

As such, the sustain electrode driver 500 according to an exemplary embodiment of the present invention has a waveform such as an overshoot or undershoot by electrically connecting the clamping unit 530 between the sustain discharge voltage supply unit 520 and the panel capacitor Cp. Stable holding period is achieved by preventing the occurrence of distortion.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to an exemplary embodiment of the present invention, the clamping diode may be connected between the sustain discharge voltage supply unit and the panel capacitor to prevent waveform distortion such as overshoot or undershoot that may occur when the sustain discharge voltage is supplied. Therefore, there is an effect of equalizing the luminance according to the load by making the sustain discharge start voltage constant.

Claims (6)

A plasma display panel including a first electrode and a second electrode, the panel capacitor being formed between the first and second electrodes; And A driving unit for applying a sustain discharge pulse alternately having a first voltage and a second voltage lower than the first voltage to the first and second electrodes in the sustain period of each subfield, The driving unit, A power recovery unit for charging and discharging the panel capacitor for a predetermined time; A sustain discharge voltage supply unit electrically connected between the power recovery unit and the panel capacitor to maintain the predetermined time by applying the first voltage or the second voltage to the panel capacitor; And a clamping unit electrically connected between the sustain discharge voltage supply unit and the panel capacitor to maintain the voltage of the panel capacitor not higher than the first voltage and not lower than the second voltage. . The method of claim 1, The clamping unit, A first clamping diode electrically connected between a first power supply for supplying the first voltage and the first electrode; And a second clamping diode electrically connected between a second power supply for supplying the second voltage and the first electrode. The method of claim 2, The first clamping diode has a cathode connected to the first power supply and an anode connected to the first electrode, The second clamping diode is an anode connected to the second power source and a cathode connected to the first electrode. The method according to claim 2 or 3, The power recovery unit, A first capacitor charging a third voltage between the first voltage and the second voltage, A first inductor electrically connected to the first electrode and the first end; A first switching element electrically connected between the first capacitor and the first inductor to form a charging path to the first electrode; A second switching element electrically connected between the first capacitor and the first inductor to form a discharge path to the first electrode, The sustain discharge voltage supply unit, A third switching element electrically connected between a first power supply for supplying the first voltage and the first electrode; And a fourth switching element electrically connected between the second power supply for supplying the second voltage and the first electrode. The method of claim 4, wherein In the first period, the first switching device is turned on to increase the voltage of the first electrode to the first voltage by using resonance of the first inductor and the first electrode. In the second period, the first switching device is turned off and the third switching device is turned on to maintain the first voltage applied to the first electrode. In the third period, the third switching device is turned off and the second switching device is turned on to reduce the voltage of the first electrode to the second voltage by using the resonance of the second inductor and the first electrode. In the fourth period, the second switching device is turned off and the fourth switching device is turned on to maintain the second voltage applied to the first electrode. When the overshoot occurs when the first voltage is applied to the first electrode in the second period, the first clamping diode is turned on. And the second clamping diode is turned on when an undershoot occurs when the second voltage is applied to the first electrode in the fourth period. The method according to any one of claims 1 to 5, And the first electrode is a sustain electrode.

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