KR100631122B1 - Plasma display and driving method thereof - Google Patents

Abstract

The present invention relates to a plasma display device and a driving method thereof for reducing electromagnetic interference (EMI).

The plasma display device includes: a first driver supplying the sustain pulse to first electrodes; A second driver supplying the sustain pulse to second electrodes; The first driver is controlled to display a predetermined phase difference between the sustain pulses supplied to the neighboring first electrodes, and the second driver is controlled to alternately operate with the first driver. It is provided with a control unit that varies in units of a predetermined period.

Description

Plasma display and driving method {PLASMA DISPLAY AND DRIVING METHOD THEREOF}             

FIG. 1 is a diagram illustrating a subfield pattern for implementing 256 gray levels in a plasma display device.

2 is a plan view schematically showing an electrode arrangement of a three-electrode alternating surface discharge plasma display panel.

3 is a waveform diagram showing driving waveforms of a conventional plasma display panel.

4 is a waveform diagram illustrating a current generated by the driving waveform shown in FIG. 3.

5 is a waveform diagram illustrating driving waveforms of a plasma display device according to a first exemplary embodiment of the present invention.

6 is a waveform diagram illustrating driving waveforms of a plasma display device according to a second exemplary embodiment of the present invention.

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

<Description of Symbols for Main Parts of Drawings>

72: scan drive 74: sustain drive

76: control unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device, and more particularly, to a plasma display device and a driving method thereof for reducing electromagnetic interference (hereinafter referred to as "EMI").

The plasma display device displays an image by exciting the phosphor by using ultraviolet rays generated when an inert mixed gas such as He + Xe, Ne + Xe, He + Xe + Ne is discharged. The plasma display device is not only thin and large in size, but also has improved in image quality due to recent technology development.

The plasma display device is time-divisionally driven by dividing one frame into several subfields having different number of emission times in order to implement grayscale of an image. Each subfield is divided into a reset period for initializing the full screen, an address period for selecting a scan line and selecting a discharge cell in the selected scan line, and a sustain period for implementing gradation according to the number of discharges. For example, when the image is to be displayed with 256 gray levels, the frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields SF1 to SF8 as shown in FIG. As described above, each of the eight subfields SF1 to SF8 is divided into an initialization period, an address period, and a sustain period. The initialization period and the address period of each subfield are the same for each subfield, while the sustain period and the number of sustain pulses allocated thereto are 2 ⁿ (n = 0,1,2,3,4,5,6) in each subfield. , 7).

2 schematically shows an electrode arrangement of a conventional three-electrode alternating surface discharge plasma display panel (hereinafter referred to as "PDP").

Referring to FIG. 2, the conventional three-electrode AC surface discharge type PDP includes scan electrodes Y1 to Yn and sustain electrodes Z, scan electrodes Y1 to Yn, and sustain electrodes Z formed on an upper plate. Address electrodes X1 to Xm formed on the lower plate to be orthogonal to each other.

At the intersections of the scan electrodes Y1 to Yn, the sustain electrodes Z and the address electrodes X1 to Xm, discharge cells 1 for displaying any one of red, green and blue are arranged in a matrix form. Is placed.

On the top plate on which the scan electrodes Y1 to Yn and the sustain electrodes Z are formed, a dielectric layer and an MgO protective layer (not shown) are stacked.

On the lower plate where the address electrodes X1 to Xm are formed, partition walls are formed between the discharge cells 1 to prevent optical and electrical interference. On the lower plate and the partition wall surface, phosphors are excited by ultraviolet rays and emit visible light.

An inert mixed gas such as He + Xe, Ne + Xe, He + Xe + Ne is injected into the discharge space between the upper and lower plates of the PDP.

3 illustrates a driving waveform supplied to the PDP as shown in FIG. 2.

Referring to FIG. 3, each of the subfields SFn-1 and SFn includes a reset period RP for initializing the discharge cells 1 of the full screen, an address period AP for selecting a discharge cell, A sustain period SP for maintaining the discharge of the selected discharge cells 1 and an erasing period EP for erasing the wall charges in the discharge cell 1.

The erase ramp waveform ERR is applied to the sustain electrodes Z in the erase period EP of the n−1 th subfield SFn−1. 0V is applied to the scan electrodes Y and the address electrodes X during the erase period EP. The erase ramp waveform ERR is a positive ramp waveform in which the voltage gradually rises from 0V to the positive sustain voltage Vs. The erase discharge is generated between the scan electrode Y and the sustain electrode Z in the on-cells in which the sustain discharge has been caused by the erase ramp waveform ERR.

In the setup period SU of the reset period RP at which the nth subfield SFn starts, the positive ramp waveform PR is applied to all the scan electrodes Y, and the sustain electrodes Z and the address electrodes are applied. 0 (V) is applied to (X). Due to the positive ramp waveform PR in the setup period UP, the voltage on the scan electrodes Y gradually rises from the positive sustain voltage Vs to a higher reset voltage Vr. The positive ramp waveform PR generates dark discharge in which light is hardly generated between the scan electrodes Y and the address electrodes X in the discharge cells of the full screen. The dark discharge also occurs between the field Y and the sustain electrodes Z. As a result of this dark discharge, positive wall charges remain on the address electrodes X and the sustain electrodes Z immediately after the setup period SU, and negative wall charges remain on the scan electrodes Y. do. The gap voltage Vg between the scan electrodes Y and the sustain electrodes Z and the scan electrodes Y and the address electrodes X during the dark discharge are generated during the setup period SU. The gap voltage between them is initialized to a voltage close to the discharge ignition voltage Vf, which can cause discharge.

Following the setup period SU, the negative ramp waveform NR is applied to the scan electrodes Y in the setdown period SD of the reset period RP. At the same time, a positive sustain voltage Vs is applied to the sustain electrodes Z, and 0 [V] is applied to the address electrodes X. Due to the negative ramp waveform NR, the voltage on the scan electrodes Y is gradually lowered from the positive sustain voltage Vs to the negative erase voltage Ve. By the negative ramp waveform NR, dark discharge is generated between the scan electrodes Y and the address electrodes X in the discharge cells of the full screen, and at almost the same time, the scan electrodes Y and the sustain electrodes ( A dark discharge occurs between Z). As a result of the dark discharge in this set-down period SD, the wall charge distribution in each of the discharge cells 1 changes to an addressable condition. At this time, unnecessary transient wall charges are erased on the scan electrodes Y and the address electrodes X in each of the discharge cells 1, and a certain amount of wall charges remains. The wall charges on the sustain electrodes Z are inverted from the positive to the negative polarity as the negative wall charges transferred from the scan electrodes Y accumulate. The gap voltage between the scan electrodes Y and the sustain electrodes Z, the scan electrodes Y and the address electrodes X during the dark discharge is generated in the set-down period SD of the reset period RP. The gap voltage between?) Is close to the discharge ignition voltage Vf.

In the address period AP, the negative scan pulse -SCNP is sequentially applied to the scan electrodes Y, and the positive data pulses are applied to the address electrodes X in synchronization with the scan pulse -SCNP. DP) is applied. The voltage of the scan pulse (-SCNP) is the scan voltage (Vsc) lowered from the negative scan bias voltage (Vyb) of 0 V or close thereto to the negative scan voltage (-Vy). The voltage of the data pulse DP is the positive data voltage Va. During this address period (AP), the sustain electrodes Z are supplied with a positive Z bias voltage Vzb lower than the positive sustain voltage Vs. Scan in the on-cells to which the scan voltage Vsc and the data voltage Va are applied while the gap voltage is adjusted to be close to the discharge ignition voltage Vf immediately after the reset period RP. The primary address discharge is generated between the electrodes Y and X while the gap voltage between the electrodes Y and the address electrodes X exceeds the discharge ignition voltage Vf. Here, the primary address discharge of the scan electrode Y and the address electrode X occurs near the edge far from the gap between the scan electrode Y and the sustain electrode Z. The primary address discharge between the scan electrodes Y and the address electrodes X generates priming charged particles in the discharge cell to induce a secondary discharge between the scan electrodes Y and the sustain electrodes Z. .

On the other hand, the wall charge distribution in the off-cells where no address discharge has occurred is substantially the same as the wall charge distribution immediately after the set down.

In the sustain period SP, sustain pulses SUSP of the positive sustain voltage Vs are alternately applied to the scan electrodes Y and the sustain electrodes Z. FIG. Then, on-cells selected by the address discharge generate a sustain discharge between the scan electrodes Y and the sustain electrodes Z at every sustain pulse SSUS. In contrast, the off-cells do not discharge during the sustain period. This is because the wall charge distribution of the off-cells is substantially the same as the wall charge distribution immediately after the set-down, and thus the scan electrodes Y and the sustain electrodes Z are applied when the initial positive sustain voltage Vs is applied to the scan electrodes Y. This is because the gap voltage between the?) Cannot exceed the discharge ignition voltage Vf.

However, the conventional plasma display device has a large EMI problem. In particular, in the plasma display device, EMI is mostly generated in the sustain period SP to which the sustain pulses SUSP are applied at a frequency of about 200 KHz or more. This is because the sustain pulses SUSP are simultaneously applied to all the scan electrodes Y1 to Yn and the sustain electrodes Z are simultaneously applied to each of the subfields so that the displacement current i is large.

Accordingly, an object of the present invention is to provide a plasma display device and a driving method thereof to reduce EMI.

In order to achieve the above object, a plasma display device according to the present invention includes a first driver for supplying the sustain pulse to the first electrode; A second driver supplying the sustain pulse to second electrodes; The first driver is controlled to display a predetermined phase difference between the sustain pulses supplied to the neighboring first electrodes, and the second driver is controlled to alternately operate with the first driver. It is provided with a control unit that varies in units of a predetermined period.

The phase difference is set to a time within 20 ns.

The predetermined period is one of a frame period and a subfield period.

A driving method of a plasma display device according to the present invention includes supplying sustain pulses to the first electrodes such that a predetermined phase difference appears between the sustain pulses supplied to neighboring first electrodes; And supplying the sustain pulse to the second electrodes alternately with the sustain pulse supplied to the first electrodes.

The phase difference is varied in predetermined period units.

Other objects and advantages other than the above object will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 5 to 7.

FIG. 5 is a driving waveform showing a driving method of the plasma display device according to the first embodiment of the present invention, and shows a driving waveform supplied to the PDP as shown in FIG.

Referring to FIG. 5, in the driving method of the PDP according to the present invention, a sustain pulse SSUS supplied to the n-1 th scan electrode Yn-1 and a sustain pulse SSUS supplied to the n th scan electrode Yn are provided. EMI can be reduced by setting the phase difference [Delta] t between them. Due to this phase difference Δt, the intensity of the displacement current i is reduced. Since the sustain electrodes Z are common electrodes, the sustain pulses SSUS are simultaneously supplied.

The phase difference [Delta] t between the sustain pulses SUSP supplied to the scan electrodes Yn-1 and Yn is a condition that does not narrow the driving margin without misdischarge or misdischarge due to discharge delay and sustain electrodes Z. It is set to approximately 20 ns or less in consideration of the overlap with the sustain pulse SUSP supplied to the.

On the basis of the rising point of the sustain pulse SSUS, between the sustain pulse SSUS supplied to the n-1 th scan electrode Yn-1 and the sustain pulse SSUS supplied to the n th scan electrode Yn. The phase difference Δt is periodically changed within 20 ns so that the timing at which the displacement current i appears varies periodically. If the timing at which the displacement current i appears is changed periodically, EMI is reduced. This EMI reduction technique is also well known in Spread Spectrum Integrated Ciruit, which is used in some electronic fields.

On the other hand, the erase period operation immediately after the reset period, the address period, and the sustain period is substantially the same as the driving waveform of FIG.

6 illustrates a method of driving a plasma display device according to a second embodiment of the present invention.

Referring to FIG. 6, in the driving method of the PDP according to the present invention, a sustain pulse SSUS supplied to the n-1 th scan electrode Yn-1 and a sustain pulse SSUS supplied to the n th scan electrode Yn are provided. The phase difference [Delta] t is set in between, but the phase difference [Delta] t is changed in subfield units (or frame period units).

k (where k is a positive integer of 2 or more) the sustain pulse SUSP and the n th scan electrode Yn supplied to the n-1 th scan electrode Yn-1 in the -1 th subfield SFk-1 The sustain pulse SSUS supplied to the n-1 th scan electrode Yn-1 in the k th subfield SFk-1 is compared with setting the phase difference Δt between the sustain pulses SSUS supplied to the 10 ns. And the phase difference [Delta] t between the sustain pulse SUSP supplied to the nth scan electrode Yn is set to 15 ns. If the phase difference Δt is set between the sustain pulses SUSP supplied to the scan electrodes Yn-1 and Yn and the phase difference Δt is changed for every subfield, the sustain pulse SSUS is changed. The intensity of the generated displacement current i is reduced, and the point in time at which the displacement current i appears is varied in subfield units (or frame period units), thereby reducing EMI.

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

Referring to FIG. 7, the plasma display device according to the exemplary embodiment of the present invention drives the scan driver 72 for driving the scan electrodes Yn-1 and Yn of the PDP, and the sustain electrodes Z of the PDP. Sustain driving section 74 for controlling, and the control unit 76 for controlling the driving units (72, 74).

The scan driver 72 supplies the sustain pulse SUSP to the n-1 th sustain electrode Yn-1 during the sustain period under the control of the controller 76, and then the sustain pulse SUSP delayed by a predetermined phase difference Δt. ) Is supplied to the nth sustain electrode Yn. 6, the scan driver 72 varies the phase difference Δt between the sustain pulses SSUS in subfield units or frame period units as shown in FIG. 6. To this end, the scan driver 72 switches the switches for supplying the base voltage GND or 0V under the control of the controller 76, and switches switched in response to the control signals S1 and S2 of the controller 76. Include.

The sustain driver 74 alternately operates with the scan driver 72 during the sustain period under the control of the controller 76 to supply the sustain pulse SUSP to the sustain electrodes Z. FIG.

The controller 76 generates a switch control signal for controlling the scan driver 74 and the sustain driver 76 in response to a phase difference Δt signal that is set within 20 ns and varies in units of subfields or frame periods. The scan driver 74 and the sustain driver 76 are controlled.

As described above, the plasma display device and the driving method thereof according to the present invention set the phase difference between the sustain pulses supplied to the scan electrodes and change the phase difference periodically or aperiodically to reduce the intensity of the current and reduce the current. By varying the time at which the appears, EMI of the plasma display can be reduced.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (6)

A plasma display device having a first electrode group including a plurality of first electrodes supplied with a sustain pulse, and a second electrode group including a plurality of second electrodes. A first driver supplying the sustain pulse to the first electrodes; A second driver supplying the sustain pulse to the second electrodes; The second driver is controlled to alternately operate with the first driver while controlling the first driver so that a predetermined phase difference is generated between the sustain pulses supplied to neighboring first electrodes among the first electrodes. And a control unit for controlling and varying the predetermined phase difference in a predetermined period unit. The method of claim 1, And the phase difference is set to a time within 20 ns. The method of claim 1, And said predetermined period is one of a frame period and a subfield period. A driving method of a plasma display device having a first electrode group including a plurality of first electrodes supplied with a sustain pulse and a second electrode group including a plurality of second electrodes, the method comprising: Supplying sustain pulses to the first electrodes such that a predetermined phase difference appears between the sustain pulses supplied to neighboring first electrodes among the first electrodes; Supplying the sustain pulse to the second electrodes alternately with the sustain pulse supplied to the first electrodes; And the predetermined phase difference is varied in predetermined period units. The method of claim 4, wherein And the phase difference is set to a time within 20 ns. The method of claim 4, wherein And the predetermined period is any one of a frame period and a subfield period.

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