KR20060126269A - Plasma display apparatus and driving method thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to increase the contrast characteristic by making the absolute value of the gradient of ramp-down pulse included in setdown pulse supplied to a scan electrode during a setdown period of a reset period in a subfield where setup pulse including ramp-up pulse is supplied to the scan electrode during a setup period of the reset period, smaller than that of the other subfield. A plasma display device includes a plasma display panel(500) having scan electrodes(Y1~Yn); a scan driving unit(503) driving the scan electrodes; and a setdown pulse control unit(501) controlling the gradient of ramp-down pulse applied during a setdown period of a reset period of at least one subfield, differently from the gradient of ramp-down pulse applied during the setdown period of the reset period of the rest subfields, by controlling the scan driving unit.

Description

Plasma Display Apparatus and Driving Method Thereof

1 is a diagram showing the structure of a typical plasma display panel.

2 is a view showing a coupling relationship between a plasma display panel and a driver;

3 is a view showing a driving waveform for driving a plasma display panel in a conventional plasma display device.

4 is a view for explaining a method in which the rising ramp is supplied once in one frame in the conventional driving waveform.

5 is a diagram for explaining the structure of a plasma display device of the present invention;

6 is a view for explaining an embodiment of a method of driving a plasma display panel of the present invention.

FIG. 7 is a view for comparing an optical waveform shown according to the driving method of the plasma display panel of the present invention of FIG. 6 with an optical waveform shown according to the conventional driving waveform of FIG. 4.

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

500: plasma display panel 501: set-down pulse control unit

502: data driver 503: scan driver

504: sustain driver 505: drive voltage generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel, and more particularly, to a plasma display device and a method of driving the same, which improve contrast by adjusting a slope of a set down pulse supplied to a scan electrode during a reset period. It is about.

In general, a plasma display panel is a partition wall formed between a front panel and a rear panel to form one unit cell, and each cell includes neon (Ne), helium (He), or a mixture of neon and helium (Ne + He) and An inert gas containing the same main discharge gas and a small amount of xenon is filled. When discharged by a high frequency voltage, the inert gas generates vacuum ultra violet rays and emits phosphors formed between the partition walls to realize an image. Such a plasma display panel has a spotlight as a next generation display device because of its thin and light configuration.

1 illustrates a structure of a general plasma display panel.

As shown in FIG. 1, the plasma display panel includes a front panel in which a plurality of sustain electrode pairs formed by pairing a scan electrode 102 and a sustain electrode 103 are arranged on the front glass 101, which is a display surface on which an image is displayed. 100 and the rear panel 110 having a plurality of address electrodes 113 arranged to intersect the plurality of storage electrode pairs described above on the rear glass 111 forming the rear surface are coupled in parallel with a predetermined distance therebetween. .

The front panel 100 is made of a scan electrode 102 and a sustain electrode 103, that is, a transparent electrode (a) formed of a transparent ITO material and a metal material to mutually discharge and maintain light emission of the cells in one discharge cell. The scan electrode 102 and the sustain electrode 103 provided as the bus electrode b are included in pairs. The scan electrode 102 and the sustain electrode 103 are covered by one or more upper dielectric layers 104 that limit the discharge current and insulate the electrode pairs, and facilitate discharge conditions on top of the upper dielectric layer 104. In order to do this, a protective layer 105 on which magnesium oxide (MgO) is deposited is formed.

The rear panel 110 is arranged in such a manner that a plurality of discharge spaces, that is, barrier ribs 112 of a stripe type (or well type) for forming discharge cells are maintained in parallel. In addition, a plurality of address electrodes 113 which perform address discharge to generate vacuum ultraviolet rays are arranged in parallel with the partition wall 112. The upper surface of the rear panel 110 is coated with R, G, and B phosphors 114 that emit visible light for image display during address discharge. A lower dielectric layer 115 is formed between the address electrode 113 and the phosphor 114 to protect the address electrode 113.

The plasma display panel having the above-described structure is provided with a plurality of discharge cells in a matrix structure, and a driving unit including a driving circuit for supplying a predetermined pulse to the discharge cells is attached and driven. The coupling relationship between the plasma display panel and the driving unit is illustrated in FIG. 2.

2 is a diagram illustrating a coupling relationship between a plasma display panel and a driver.

As shown in FIG. 2, the driver includes, for example, a data driver 201, a scan driver 202, and a sustain driver 203. These driving units 201, 202, and 203 are connected to the plasma display panel 200 to form one plasma display device.

Here, the plasma display panel 200 is supplied with a data pulse from the data driver 201. These data pulses are generated when an image signal input from the outside goes through a predetermined signal processing process. The plasma display panel 200 receives the scan pulse and the sustain pulse output from the scan driver 202, and the sustain pulse output from the sustain driver 203. As described above, a discharge occurs in a cell selected by the scan pulse among a plurality of cells included in the plasma display panel 200 that receives the data pulse, the scan pulse, the sustain pulse, and the like, and the discharged cell emits light with a predetermined luminance. . The data driver 201, the scan driver 202, and the sustain driver 203 may be formed of an address electrode, a scan electrode, and a sustain electrode of the plasma display panel 200 through a connection such as a flexible printed circuit (FPC) (not shown). Are each connected to.

The driving waveform for driving the plasma display panel in the plasma display apparatus is shown in FIG. 3.

3 is a view showing a driving waveform for driving a plasma display panel in a conventional plasma display device.

As shown in Fig. 3, the plasma display panel erases a reset period for initializing all cells, an address period for selecting a cell to be discharged, a sustain period for maintaining the discharge of the selected cell, and a wall charge in the discharged cell. It is divided into an erase period for driving.

In the reset period, a rising ramp waveform Ramp-up is simultaneously applied to all scan electrodes in the setup period. This rising ramp waveform causes weak dark discharge in the discharge cells of the entire screen. By this setup discharge, positive wall charges are accumulated on the address electrode and the sustain electrode, and negative wall charges are accumulated on the scan electrode.

During the set-down period, after the rising ramp waveform is supplied, the falling ramp waveform (Ramp-down) begins to fall from the positive polarity voltage lower than the peak voltage of the rising ramp waveform and falls to a specific voltage level below the ground (GND) level voltage. By generating a weak erase discharge in the cells, the wall charges excessively formed in the scan electrode are sufficiently erased. By this set down discharge, the wall charges to the extent that the address discharge can be stably generated remain uniformly in the cells.

In the address period, negative polarity scan pulses are sequentially applied to the scan electrodes, and data pulses of positive polarity 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 between the reset periods are added, an address discharge is generated in the discharge 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 the sustain voltage Vs is applied. The sustain electrode is supplied with a positive voltage Vz so as to reduce the voltage difference with the scan electrode in at least one of the set down period and the address period so that no misdischarge occurs with the scan electrode.

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

After the sustain discharge is completed, in the erase period, the voltage of the erase ramp waveform Ramp-ers having a small pulse width and voltage level is supplied to the sustain electrode to erase the wall charge remaining in the cells of the entire screen.

In the conventional plasma display panel, such a driving waveform is supplied for every subfield of the frame.

On the other hand, the ramp-up supplied to the scan electrode in the above-mentioned reset period is a high voltage pulse of about 400V, so that the amount of light generated by the discharge generated by the ramp is relatively large. Therefore, the luminance in the state where all the discharge cells of the plasma display panel are turned off, that is, the black luminance is relatively large, resulting in deteriorated contrast characteristics.

In order to prevent such deterioration of contrast characteristics, a method of allowing the rising ramp to be supplied once in one frame has been conventionally proposed. Looking at it as shown in FIG.

FIG. 4 is a diagram for describing a method of supplying a rising ramp once in one frame in a conventional driving waveform.

As shown in Fig. 4, when one frame consists of a plurality of subfields, only the reset pulses supplied in the setup period of the reset period of any one of the plurality of subfields include the rising ramp. do. For example, as shown in FIG. 4, a reset pulse including a rising ramp is supplied to a set-up period in a reset period of a subfield having the smallest weight among the plurality of subfields of one frame, for example, the first subfield. In the subfield, a reset pulse for maintaining a predetermined positive polarity voltage, for example, the sustain voltage Vs, is supplied in the setup period of the reset period. Accordingly, the contrast characteristics are improved by substantially reducing the number of rising ramp pulses supplied in one frame compared to the driving waveform of FIG. 3.

Meanwhile, in the subfield including the rising ramp pulse in the reset period among the subfields of the frame, the slope ΔV / Δt of the setdown pulse supplied in the setdown period is set in the setdown period of the other subfields. It is equal to the slope of the down pulse. The greater the absolute value of the slope of the set down pulse supplied in this set down period, that is, the greater the rate of change in voltage per hour, the greater the amount of light generated in the set down period. This has a greater influence on the change of the optical waveform in the set down period.

Specifically, in a subfield including a rising ramp pulse in the setup period of the reset period among the subfields of the frame, discharge is performed in both the on and off cells by the rising ramp pulse supplied in the setup period of the reset period. This happens. Accordingly, in the subfield including the rising ramp pulse in the setup period of the reset period among the subfields of such a frame, discharge is generated in both the on and off cells by the set down pulse supplied in the set down period. Occurs.

As described above, in the subfield including the rising ramp pulse in the set-up period of the reset period among the subfields of the frame, the absolute value of the slope of the set-down pulse supplied in the set-down period increases in this set-down period. There is a problem that the contrast characteristics are deteriorated by increasing the amount of light to make the black luminance relatively large.

SUMMARY OF THE INVENTION In order to solve this problem, an object of the present invention is to provide a plasma display device and a method of driving the same, which improve contrast characteristics by adjusting a slope of a set down pulse supplied to a scan electrode during a reset period.

The plasma display apparatus of the present invention for achieving the above object is controlled in the set-down period of the reset period of the at least one predetermined subfield by controlling the plasma display panel including the scan electrode, the scan driver and the scan driver for driving the scan electrode A set-down pulse control unit for controlling the slope of the applied ramp-down pulse differently from the slope of the ramp-down pulse applied in the set-down period of the reset period of the remaining subfields except for the predetermined subfield. It is characterized by including.

Further, the set down pulse controller controls the absolute value of the slope of the ramp-down pulse applied in the set down period of the reset period of the predetermined subfield to the set down period of the reset period of the remaining subfields except for the predetermined subfield. It characterized in that the control to be smaller than the absolute value of the slope of the applied ramp-down pulse (Ramp-Down) pulse.

In addition, the set-down pulse controller controls the set-down of the reset period following the set-up period when the set-up pulse including the ramp-up pulse is supplied to the scan electrode in the set-up period of the reset period of the predetermined subfield. It is characterized in that the slope of the ramp-down pulse included in the set-down pulse supplied to the scan electrode in the period is smaller than the other subfields.

The predetermined subfield may be the first subfield among the subfields of one frame.

The predetermined subfield may be a subfield having the lowest gray scale weight among the subfields of one frame.

Further, the slope difference of the falling ramp pulse applied in the set down period of the reset period of the predetermined subfield and the falling ramp pulse applied in the set down period of the reset period of the remaining subfields except for the predetermined subfield is 0.1V /. It is characterized by more than us.

Hereinafter, exemplary embodiments of the plasma display apparatus and the driving method will be described in detail with reference to the accompanying drawings.

5 is a view for explaining the structure of the plasma display device of the present invention.

As shown in FIG. 5, the plasma display apparatus of the present invention includes scan electrodes Y ₁ to Yn and sustain electrodes Z, and a plurality of address electrodes X ₁ to X that intersect the scan electrodes and sustain electrodes Z. As shown in FIG. Xm) and at least one subfield to which a driving pulse is applied to the address electrodes X ₁ to Xm, the scan electrodes Y ₁ to Yn, and the sustain electrode Z in the reset period, the address period and the sustain period. A combination of a plasma display panel 500 representing a frame-shaped image, a data driver 502 for supplying data to address electrodes X ₁ to Xm formed in the plasma display panel 500, and a scan electrode s (Y ₁ to Yn) and the scan driver 503 for driving the common electrode and the sustain driver 504 for driving the sustain electrodes (Z), a plasma display panel 500 is driven A set-down pulse controller 501 for controlling the operation of the scan driver 503 in the set-down period, and a drive voltage generator 505 for supplying a drive voltage necessary for each of the drivers 502, 503, 504. It includes.

Here, the aforementioned plasma display panel 500 is bonded to the front panel (not shown) and the rear panel (not shown) at regular intervals, and a plurality of electrodes, for example, scan electrodes (Y ₁ to Yn) and sustain. A plurality of sustain electrodes including the electrodes Z are formed, and the address electrodes X ₁ to Xm are formed to intersect the sustain electrodes including the scan electrodes Y ₁ to Yn and the sustain electrode Z. do.

The data driver 502 is subjected to inverse gamma correction and error diffusion by an inverse gamma correction circuit, an error diffusion circuit, and the like not shown, and then data mapped to each subfield is supplied by the subfield mapping circuit. The data driver 502 samples and latches data in response to a data timing control signal CTRX from a timing controller (not shown), and then supplies the data to the address electrodes X ₁ to Xm. .

The scan driver 503 supplies a setup pulse, for example, a rising ramp waveform Ramp-up, to the scan electrodes Y ₁ to Yn during the set up period of the reset period, and also under the control of the set down pulse controller 501. The falling ramp waveform Ramp-down is supplied to the scan electrodes Y ₁ to Yn during the set down period of the reset period. In addition, the scan driver 503 sequentially supplies the scan pulse Sp of the scan voltage (-Vy) to the scan electrodes Y ₁ to Yn during the address period, and supplies the sustain pulse SUS during the sustain period. To Y (Y ₁ to Yn).

The sustain driver 504 supplies the bias voltage Vz to the sustain electrodes Z during at least one of a set down period or an address period under the control of a timing controller (not shown), and the scan driver 503 during the sustain period. It alternately operates to supply the sustain pulse SUS to the sustain electrodes Z.

The set down pulse control unit 501 generates a timing control signal CTRY for controlling the operation timing and synchronization of the scan driver 503 in the set down period of the reset period, and transmits the timing control signal CTRY to the scan driver 503. ), The scan driver 503 is controlled. In particular, the set-down pulse controller 501 described above controls the scan driver 503 described above to apply the ramp down to the set-down period of the reset period of one or more predetermined subfields of one frame subfield. The slope of the pulse is different from the slope of the falling ramp pulse applied to the set-down period of the reset period of the remaining subfields except the predetermined subfield.

Here, more preferably, when the ramp-up pulse is supplied to the predetermined subfield in the set-up period of the reset period, it is supplied to the scan electrode in the set-down period of the reset period following the set-up period. The absolute value of the slope of the ramp-down pulse, which is a set-down pulse, is smaller than other subfields.

The data control signal CTRX described above includes a sampling clock for sampling data, a latch control signal, and a switch control signal for controlling on / off time of the driving switch element. The scan control signal CTRY includes an energy recovery circuit in the scan driver 503 and a switch control signal for controlling the on / off time of the driving switch element. The sustain control signal CTRZ includes the energy in the sustain driver 504. A switch control signal for controlling the on / off time of the recovery circuit and the drive switch element is included.

The driving voltage generator 505 generates a setup voltage Vsetup, a scan reference voltage Vscan, a scan voltage -Vy, a sustain voltage Vs, a data voltage Vd, and the like. These driving voltages may vary depending on the composition of the discharge gas or the structure of the discharge cell.

The driving of the plasma display device of the present invention having such a structure will be more apparent through the following description of the driving method of the plasma display panel of the present invention.

6 is a view for explaining an embodiment of a method of driving a plasma display panel of the present invention.

Referring to FIG. 6, in one embodiment of the method of driving a plasma display panel, a slope of a ramp-down pulse applied to a set-down period of a reset period of one or more predetermined subfields of one or more subfields of a frame is determined. It is different from the slope of a ramp-down pulse applied in the set-down period of the reset period of the remaining subfields except the above-described predetermined subfield. Here, preferably, the absolute value of the slope of the ramp-down pulse applied in the set down period of the reset period of the predetermined subfield is set in the set down period of the reset period of the remaining subfields except the predetermined subfield. It is less than the absolute value of the slope of the applied ramp-down pulse.

Herein, a subfield in which the absolute value of the slope of the ramp-down pulse included in the set-down pulse supplied to the scan electrode in the set-down period of the reset period following the set-up period is smaller than the other subfields is a frame. It is preferable that the subfield be a set-up pulse including a ramp-up pulse to the scan electrode Y in the set-up period of the reset period. In other words, in the subfield in which the setup pulse including the ramp-up pulse is supplied to the scan electrode Y in the setup period of the reset period among the subfields of the frame, the scan is performed in the setdown period of the reset period. The absolute value of the slope of the ramp-down pulse included in the set-down pulse supplied to the electrode Y is made smaller than other subfields.

Preferably, as described above, the subfield to which the set-up pulse including the ramp-up pulse is supplied to the scan electrode Y in the set-up period of the reset period has a gray scale weight among the subfields of the frame. It is the lowest subfield.

In addition, the subfield to which the setup pulse including the ramp-up pulse is supplied to the scan electrode Y in the setup period of the reset period is preferably the first subfield of the subfield of the frame.

For example, as shown in FIG. 6, a subfield having a different magnitude of the absolute value of the slope of the set-down pulse in the first subfield of the frame, that is, a set in the subfield from the second subfield to the eighth subfield. It is smaller than the magnitude of the absolute value of the slope of the down pulse.

As such, the reason for making the absolute value of the slope of the set down pulse supplied in the set down period in one or more of the subfields of the frame smaller than other subfields, i.e., make the slope gentle, is due to the slope of the set down pulse. The smaller the absolute value is, the smaller the rate of change of the voltage per hour is to improve the contrast characteristic by reducing the amount of light generated in the set-down period. As described above, the reason why the amount of light generated in the set-down period decreases as the absolute value of the slope of the set-down pulse is smaller, that is, when the slope is gentle, will be clarified in the following description of FIG. 7.

In addition, the reason why the absolute value of the slope of the set-down pulse is small, that is, the slope is gentle only in the subfield to which the rising ramp pulse is supplied in the setup period of the reset period among the subfields of the frame is because In the subfield in which the rising ramp pulse is not supplied in the setup period, the reset pulse supplied in the reset period does not have a voltage value sufficient to cause a discharge in an off discharge cell not selected by the address discharge. Since the amount of light generated in the set-down period by the set-down pulse is relatively small, which contributes to the deterioration of the contrast characteristic, the rising ramp pulse is generated in the setup period of the reset period among the subfields of the frame as described above. The absolute value of the slope of the set down pulse is made small, i.e. only in the subfield to be supplied. To have a gentler cry.

In addition, in the subfield in which the setup pulse including the ramp-up pulse is supplied to the scan electrode Y in the setup period of the reset period among the subfields of the frame, the scan electrode in the setdown period of the reset period The difference between the absolute value of the slope of the ramp-down pulse included in the set down pulse supplied to (Y) and the absolute value of the slope of the ramp ramp of the other subfield is 0.1 V / us or more. It can improve more. That is, the absolute value of the slope of the set down pulse of the subfield to which the rising ramp pulse is supplied in the setup period of the reset period among the subfields of the frame is 0.1 V / us or more than the absolute value of the slope of the set down pulse of the other subfield. It is small.

Referring to FIG. 7, the change in the optical waveform is improved by changing the inclination in the set-down period during the reset period as shown in FIG. 6.

FIG. 7 is a diagram for comparing an optical waveform shown according to the driving method of the plasma display panel of the present invention of FIG. 6 with an optical waveform shown according to the conventional driving waveform of FIG. 4.

Referring to FIG. 7, (a) is an optical waveform generated by a set down pulse of the conventional drive waveform of FIG. 4, and (b) shows a rising ramp pulse in a setup period of a reset period among subfields of FIG. The optical waveform of the set-down pulse of the supplied subfield, that is, the first subfield, is shown.

Here, looking at (a), the absolute value of the slope of the set-down pulse is larger than (b). That is, the slope is more urgent. This causes a relatively large amount of light to be generated at the time when the set-down pulse starts to fall due to a large rate of change in voltage per hour, and a relatively large amount of light is generated throughout the set-down period. Such a case (a) is a case where the contrast characteristic is deteriorated by making the change of the optical waveform unstable and relatively increasing the black luminance.

On the other hand, in the case of (b), the absolute value of the slope of the set-down pulse is smaller than that of (a). That is, the slope is more gentle. In (b), the rate of change in voltage per hour is small, so that a relatively small amount of light is generated even when the set-down pulse starts to fall, and the amount of light generated in the entire set-down period is relatively small. As a result, as shown in (b), the change in the optical waveform is stabilized and the black luminance is relatively decreased, thereby improving the contrast characteristic.

As such, the technical configuration of the present invention described above can be understood by those skilled in the art that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the exemplary embodiments described above 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 foregoing detailed description, and the meaning and scope of the claims are as follows. 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 in detail above, the present invention provides a set of reset periods in a subfield in which a setup pulse including a ramp-up pulse is supplied to a scan electrode in a set-up period of a reset period among subfields of one frame. The absolute value of the slope of the ramp-down pulse included in the set-down pulse supplied to the scan electrode in the down period is smaller than other subfields, thereby improving contrast characteristics.

Claims (6)

A plasma display panel including a scan electrode; A scan driver for driving the scan electrode; And By controlling the scan driver, a slope of a ramp-down pulse applied to the set-down period of the reset period of one or more predetermined subfields is applied to the set-down period of the reset period of the remaining subfields except the predetermined subfield. And a set down pulse controller configured to control the slope of the ramp-down pulse different from the slope of the ramp-down pulse. The method of claim 1, The set down pulse control unit sets the absolute value of the slope of the ramp-down pulse applied in the set down period of the reset period of the predetermined subfield to the set down period of the reset period of the remaining subfields except the predetermined subfield. Plasma display device characterized in that it is controlled to be smaller than the absolute value of the slope of the ramp-down pulse applied to. The method of claim 1, The set down pulse controller is When a set-up pulse including a ramp-up pulse is supplied to the scan electrode in the set-up period of the reset period of the predetermined subfield, in the set-down period of the reset period following the set-up period, And an absolute value of a slope of a ramp-down pulse included in the set-down pulse supplied to the scan electrode is smaller than other subfields. The method of claim 3, wherein And the predetermined subfield is the first subfield among the subfields of one frame. The method of claim 3, wherein And the predetermined subfield is a subfield having the lowest gray scale weight among the subfields of one frame. The method according to any one of claims 1 to 3, The slope difference of the falling ramp pulse applied in the set down period of the reset period of the predetermined subfield and the falling ramp pulse applied in the set down period of the reset period of the remaining subfields except for the predetermined subfield are 0.1 V / us. The above is a plasma display apparatus characterized by the above-mentioned.

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