KR20090035383A - Plasma display apparatus - Google Patents

Abstract

A plasma display device is provided to improve an image quality and to improve a contrast property by reducing a light amount generated by a reset discharge. A plasma display device includes a plasma display panel and a driving part. A scan electrode and a sustain electrode are arranged on the plasma display panel. The driving part supplies a first reset signal(RS1) to the scan electrode in a reset period(RP) of a first sub field(SF1), supplies a second reset signal(RS2) to the scan electrode in a reset period of a second sub field, and supplies a sustain signal to one among the scan electrode and the sustain electrode in a sustain period(SP) of a reset period of the second sub field. The first reset signal and the second reset signal include a set up period, a smoothing period, and a set down period.

Description

Plasma Display Apparatus {Plasma Display Apparatus}

The present invention relates to a plasma display device.

The plasma display apparatus includes a plasma display panel.

In the plasma display panel, a phosphor layer is formed in a discharge cell divided by a partition, and a plurality of electrodes are formed.

When the drive signal is supplied to the electrode of the plasma display panel, the discharge is generated by the drive signal supplied in the discharge cell. Here, when discharged by a drive signal in the discharge cell, the discharge gas filled in the discharge cell generates vacuum ultraviolet rays, and the vacuum ultraviolet light emits the phosphor formed in the discharge cell to emit visible light. Generate. The visible light displays an image on the screen of the plasma display panel.

One aspect of the present invention is to provide a plasma display device that prevents the occurrence of erroneous discharge and improves the contrast (contrast) characteristics.

According to an embodiment of the present invention, a plasma display apparatus includes a plasma display panel in which scan electrodes and a sustain electrode are arranged in parallel with each other, and a scan electrode in a reset period of a first sub-field of a frame. A reset signal is supplied, a second reset signal is supplied to the scan electrode in the reset period of the second subfield, and a sustain signal is supplied to at least one of the scan electrode and the sustain electrode in the sustain period of the reset period of the second subfield. A first reset signal and a second reset signal, each of which includes a set-up period in which a rising ramp signal at which a voltage gradually rises is supplied, a flat period in which a maximum voltage of the rising ramp signal is maintained, and a voltage drop in which a voltage gradually falls Includes a set down period in which the ramp signal is supplied, and the sustain signal gradually increases in voltage. A rising period, a holding period for holding the maximum voltage, and a falling period in which the voltage gradually falls, the maximum voltage of the second reset signal is lower than the maximum voltage of the first reset signal, and The length may be longer than the length of the flat period of the first reset signal, and the length of the flat period of the second reset signal may be 5 times or more and 52 times less than the length of the sustain period.

The length of the flat period of the second reset signal may be 11 times or more and 29 times or less of the length of the sustain period.

In addition, the second subfield may be disposed later in time than the first subfield.

In addition, the first reset signal may be plural.

Also, the maximum voltage of the second reset signal may be lower than or equal to the maximum voltage of the sustain signal.

Plasma display panel according to an embodiment of the present invention has the effect of preventing the occurrence of mis-discharge and improve the contrast characteristics, thereby improving the image quality of the image.

Hereinafter, an embodiment of a plasma display device according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining the configuration of a plasma display device according to an embodiment of the present invention.

1, a plasma display apparatus according to an embodiment of the present invention includes a plasma display panel 100 and a driver 110.

The plasma display panel 100 may include scan electrodes Y1 to Yn and sustain electrodes Z1 to Zn that are parallel to each other, and may include address electrodes X1 to Xm that cross the scan electrode and the sustain electrode.

The driver 110 may supply a driving signal to at least one of a scan electrode, a sustain electrode, and an address electrode of the plasma display panel 100 to implement an image on the screen of the plasma display panel 100.

Here, in FIG. 1, only the case in which the driving unit 110 is formed in one board form is illustrated, but in the present invention, the driving unit 110 is divided into a plurality of board forms according to electrodes formed on the plasma display panel 100. It is also possible to lose. For example, the driver 110 may include a first driver (not shown) for driving the scan electrode of the plasma display panel 100, a second driver for driving the sustain electrode, and a third driver (not shown) for driving the address electrode. Can be divided into

2 is a diagram for explaining the structure of a plasma display panel.

Referring to FIG. 2, the plasma display panel 100 includes a front substrate 201 in which scan electrodes 202 and Y and sustain electrodes 203 and Z are parallel to each other, and scan electrodes 202 and Y and a sustain electrode ( The back substrate 211 on which the address electrodes 213 and X intersect with 203 and Z may be formed.

On the front substrate 201 where the scan electrodes 202 and Y and the sustain electrodes 203 and Z are formed, the discharge currents of the scan electrodes 202 and Y and the sustain electrodes 203 and Z are limited and the scan electrodes 202 and Y are restricted. ) And an upper dielectric layer 204 may be arranged to insulate between the sustain electrodes 203 and Z.

A protective layer 205 may be formed on the front substrate 201 where the upper dielectric layer 204 is formed to facilitate discharge conditions. The protective layer 205 may include a material having a high secondary electron emission coefficient, such as magnesium oxide (MgO) material.

The address electrodes 213 and X are formed on the rear substrate 211, and the address electrodes 213 and X are covered on the upper side of the rear substrate 211 on which the address electrodes 213 and X are formed. A lower dielectric layer 215 may be formed that insulates X).

On top of the lower dielectric layer 215, a partition space 212, such as a stripe type, a well type, a delta type, a honeycomb type, etc., is formed on the discharge space, that is, to partition the discharge cells. Can be. Accordingly, red (R), green (G), and blue (B) discharge cells may be formed between the front substrate 201 and the rear substrate 211.

In addition to the red (R), green (G), and blue (B) discharge cells, it is also possible to further form a white (W) or yellow (Yellow: Y) discharge cell.

Meanwhile, the widths of the red (R), green (G), and blue (B) discharge cells may be substantially the same, but at least one of the red (R), green (G), and blue (B) discharge cells may have a width. It may be different from the width of other discharge cells.

For example, the width of the red (R) discharge cell is the smallest, and the width of the green (G) and blue (B) discharge cells can be made larger than the width of the red (R) discharge cell. Then, color temperature characteristics of the image to be implemented may be improved. The width of the green (G) discharge cell may be substantially the same as or different from the width of the blue (B) discharge cell.

In addition, not only the structure of the partition 212 illustrated in FIG. 2, but also the structure of the partition having various shapes may be possible. For example, the partition 212 includes a first partition 212b and a second partition 212a, where the height of the first partition 212b and the height of the second partition 212a are different from each other. At least one of the first barrier rib 212b and the second barrier rib 212a, and a channel type barrier rib structure having a channel usable as an exhaust passage, at least one of the first barrier rib 212b and the second barrier rib 212a. Grooved partition wall structure having a groove formed in the groove will be possible.

In the case of the differential partition wall structure, the height of the first partition wall 212b may be lower than the height of the second partition wall 212a. In addition, in the case of the channel-type partition wall structure, a channel may be formed in the first partition wall 212b.

In addition, although the red (R), green (G), and blue (B) discharge cells are each shown and described as being arranged on the same line, it may be arranged in other shapes. For example, a delta type arrangement in which red (R), green (G) and blue (B) discharge cells are arranged in a triangular shape may be possible. In addition, the shape of the discharge cell may also be a variety of polygonal shapes, such as pentagonal, hexagonal, as well as rectangular.

In addition, in FIG. 2, only the case where the barrier rib 212 is formed on the rear substrate 211 is illustrated, but the barrier rib 212 may be formed on at least one of the front substrate 201 and the rear substrate 211.

A predetermined discharge gas may be filled in the discharge cell partitioned by the partition wall 212.

In addition, a phosphor layer 214 that emits visible light for image display may be formed in the discharge cells partitioned by the partition wall 212. For example, red (R), green (G), and blue (B) phosphor layers may be formed.

In addition to the red (R), green (G), and blue (B) phosphors, it is also possible to further form a white (W) and / or yellow (Y) phosphor layer.

In addition, the thickness of the phosphor layer 214 in at least one of the red (R), green (G), and blue (B) discharge cells may be different from other discharge cells. For example, the thickness of the phosphor layer of the green (G) discharge cell, ie the phosphor layer in the green (G) phosphor layer or the blue (B) discharge cell, ie the blue (B) phosphor layer, is It may be thicker than the thickness of the phosphor layer, ie the red (R) phosphor layer. Here, the thickness of the green (G) phosphor layer may be substantially the same as or different from the thickness of the blue (B) phosphor layer.

In addition, although the above description only shows the case where the upper dielectric layer 204 and the lower dielectric layer 215 are each one layer, at least one of the upper dielectric layer and the lower dielectric layer is not composed of a plurality of layers. It is also possible.

In addition, a black layer (not shown) may be further disposed on the partition 212 to prevent reflection of the external light due to the partition 212.

In addition, another black layer (not shown) may be further formed at a specific position on the front substrate 201 corresponding to the partition 212.

In addition, the address electrode 213 formed on the rear substrate 211 may have substantially the same width or thickness, but the width or thickness inside the discharge cell may be different from the width or thickness outside the discharge cell. . For example, the width or thickness inside the discharge cell may be wider or thicker than that outside the discharge cell.

FIG. 3 is a diagram for describing an image frame for implementing gray levels of an image in a plasma display device according to an embodiment of the present invention.

Referring to FIG. 3, an image frame for implementing gray levels of an image in a plasma display device according to an embodiment of the present invention may be divided into a plurality of subfields having different emission counts.

Although not shown, one or more subfields among the plurality of subfields may be grayed out according to a reset period for initializing discharge cells, an address period for selecting discharge cells to be discharged, and the number of discharges. It can be divided into the sustain period to implement.

For example, when an image is to be displayed with 256 gray scales, for example, one image frame is divided into eight subfields SF1 to SF8 as shown in FIG. 3, and each of the eight subfields SF1 to SF8, respectively. Can be subdivided into a reset period, an address period and a sustain period.

The gray scale weight of the corresponding subfield may be set by adjusting the number of the sustain signals supplied in the sustain period. That is, a predetermined gray scale weight can be given to each subfield using the sustain period. For example, the gray scale weight of each subfield is 2 ⁿ by setting the gray scale weight of the first subfield to 2 ⁰ and the gray scale weight of the second subfield to 2 ¹ (where n = 0, 1). , 2, 3, 4, 5, 6, and 7) to increase the gray scale weight of each subfield. As described above, the number of sustain signals supplied in the sustain period of each subfield is adjusted according to the gray scale weight in each subfield, thereby implementing gray levels of various images.

The plasma display apparatus according to an exemplary embodiment uses a plurality of image frames to implement an image, for example, to display an image of 1 second. For example, 60 image frames are used to display an image of 1 second. In this case, the length T of one image frame may be 1/60 second, that is, 16.67 ms.

In FIG. 3, only one image frame is composed of eight subfields. However, the number of subfields constituting one image frame may be variously changed. For example, one video frame may be configured with 12 subfields from the first subfield to the twelfth subfield, or one video frame may be configured with 10 subfields.

In addition, in FIG. 3, subfields are arranged in the order of increasing magnitude of gray scale weight in one image frame. Alternatively, subfields may be arranged in order of decreasing gray scale weight in one image frame. Alternatively, subfields may be arranged regardless of the gray scale weight.

4 is a view for explaining an example of the operation of the plasma display device according to an embodiment of the present invention. The driving signals to be described below are supplied by the driving unit 110 of FIG. 1.

Referring to FIG. 4, in the reset period (RP) for initializing the first subfield SF 1, the first reset signal RS1 may be supplied to the scan electrode Y. The first reset signal may include a rising ramp RU signal and a falling ramp RD signal.

For example, in the reset period, the falling ramp signal may be sequentially supplied after the rising ramp signal is supplied to the scan electrode.

Then, in the reset period, a weak dark discharge, that is, setup discharge, occurs in the discharge cell by the rising ramp signal. By this setup discharge, some wall charges can be accumulated in the discharge cells.

Thereafter, a weak erase discharge, that is, a set-down discharge, occurs in the discharge cell by the falling ramp signal. By this set-down discharge, wall charges such that address discharge can be stably generated can be uniformly retained in the discharge cells.

In addition, the rising ramp signal may include a first rising ramp signal RU1 and a second rising ramp signal RU2.

Also, the slope of the first rising ramp signal may be greater than the slope of the second rising ramp signal. Then, the effect of rapidly raising the voltage of the scan electrode before the setup discharge occurs and relatively slowly raising the voltage of the scan electrode during the setup discharge occurs, so that the length of the reset period is excessively increased. Can be prevented, and it is possible to further stabilize the setup discharge.

In the reset period, while the first reset signal is supplied to the scan electrode, the sustain electrode Z may be supplied with the protrusion signal Z IDC which can prevent excessively strong discharge from occurring between the scan electrode and the sustain electrode. have.

In the address period (period AP) after the reset period, the first scan bias signal Vsc1 substantially maintaining a voltage higher than the lowest voltage of the falling ramp signal may be supplied to the scan electrode.

In addition, the first rising signal rs1 may be supplied to the scan electrode between the first scan bias signal and the falling ramp signal. When the first rising signal is supplied, the coupling effect of adjacent electrodes may be reduced to reduce generation of noise.

In addition, in the address period, the first scan signal Scan1 falling from the first scan bias signal may be supplied to the scan electrode.

Meanwhile, the pulse width of the scan signal supplied to the scan electrode in the address period of at least one subfield may be different from the pulse width of the scan signal of another subfield. For example, the width of the scan signal in the subfield located later in time may be smaller than the width of the scan signal in the preceding subfield. In addition, the reduction of the scan signal width according to the arrangement order of the subfields can be made gradually, such as 2.6 Hz (microseconds), 2.3 Hz, 2.1 Hz, 1.9 Hz, or 2.6 Hz, 2.3 Hz, 2.3 Hz, 2.1 Hz. .... 1.9 ㎲, 1.9 ㎲ and so on.

As such, when the scan signal is supplied to the scan electrode, the data signal Data may be supplied to the address electrode X corresponding to the scan signal.

When the scan signal and the data signal are supplied, an address discharge may be generated in the discharge cell to which the data signal is supplied while the voltage difference between the scan signal and the data signal and the wall voltage generated by the wall charges generated in the reset period are added. .

The first sustain bias signal Vzb1 may be supplied to the sustain electrode Z to prevent address discharge from becoming unstable due to interference of the sustain electrode in the address period.

In the sustain period (Sustain-Period, SP) after the address period, the sustain signal may be supplied to at least one of the scan electrode and the sustain electrode. For example, a sustain signal may be alternately supplied to the scan electrode and the sustain electrode.

When such a sustain signal is supplied, the discharge cell selected by the address discharge is added with the wall voltage in the discharge cell and the sustain voltage Vs of the sustain signal, and a sustain discharge, i.e., display between the scan electrode and the sustain electrode when the sustain signal is supplied. Discharge may occur.

Meanwhile, in the at least one subfield, a plurality of sustain signals are supplied in the sustain period, and the pulse width of at least one sustain signal of the plurality of sustain signals may be different from the pulse widths of other sustain signals. For example, the pulse width of the sustain signal that is supplied first of the plurality of sustain signals may be larger than the pulse width of other sustain signals. Then, the sustain discharge can be more stabilized.

In the reset period of the second subfield SF 2, the second reset signal RS2 may be supplied to the scan electrode Y. The second reset signal may include a rising ramp signal RU signal and a falling ramp signal RD signal similarly to the first reset signal.

In the address period after the reset period, the second rising signal rs2, the second scan bias signal Vsc2, and the second scan signal Scan 2 may be supplied to the scan electrode. Here, the voltage of the second scan bias signal Vsc2 may be substantially the same as or different from the voltage of the first scan bias signal Vsc1 of the first subfield.

In addition, the third rising signal rs3 may be supplied to the sustain electrode in response to the second rising signal rs2. Then, the coupling effect between adjacent electrodes can be further weakened, and generation | occurrence | production of a noise can further be reduced.

Also, in the address period, the second sustain bias signal Vzb2 may be supplied to the sustain electrode. Here, the voltage of the second sustain bias signal Vzb2 may be different from the voltage of the first sustain bias signal Vzb1 of the first subfield and may be substantially the same.

In the sustain period after the address period, the sustain signal may be supplied to at least one of the scan electrode and the sustain electrode.

5 is a diagram for comparing a first reset signal and a second reset signal.

Referring to FIG. 5, the first reset signal and the second reset signal may include a set-up period (SU) for supplying a rising ramp signal, a flat period M for maintaining a maximum voltage of the rising ramp signal, and a falling ramp signal. It may include a set-down period (SD) to be supplied.

5, the maximum voltage of the first reset signal supplied to the scan electrode in the reset period of the first subfield as shown in (a) is Vst1, and in the reset period of the second subfield as shown in (b). The maximum voltage of the second reset signal supplied to the scan electrode is Vst2 lower than Vst1.

Comparing the first reset signal of (a) and the second reset signal of (b), the first reset signal generates a relatively strong reset discharge in the discharge cell because its maximum voltage is relatively high, and accordingly, the discharge By effectively reducing the difference in wall charge between cells, the distribution of wall charges can be made very uniform.

On the other hand, if the first reset signal of (a) is also used in the second subfield, it is possible to make the distribution of the wall charges very uniform, but the contrast characteristic may deteriorate by increasing the amount of light generated in the reset period. have. In addition, if an excessive amount of wall charges remain in the discharge cell after the sustain period of the first subfield, a strong reset discharge may occur momentarily in the reset period of the second subfield, and such a strong discharge may cause an eye to the viewer. It can be detected as a flashing bright spot. This will be called a misfire.

Therefore, in order to prevent excessive deterioration of the contrast characteristic and to prevent occurrence of bright spot discharge, it is desirable to lower the maximum voltage of the second reset signal supplied to the reset period of the second subfield to Vst2. In such a case, the amount of light generated in the reset period of the second subfield can be reduced, so that the contrast characteristic can be improved, and the occurrence of bright point false discharge can be prevented.

However, when the second reset signal is used, since the voltage of the second reset signal is relatively low, the contrast characteristic can be improved, but the probability of the distribution of the wall charges being relatively uneven increases.

In order to prevent the nonuniformity of the wall charges caused by the use of the second reset signal, the length of the flat period of the second reset signal may be longer than the length of the flat period of the first reset signal. Then, the duration of the setup discharge becomes relatively long, and the setup discharge is stabilized so that the distribution of the wall charges can be made uniform.

That is, the contrast characteristics are improved by using a first reset signal having a relatively high voltage in the first subfield and a second reset signal having a relatively low voltage in the second subfield to uniform the wall charge distribution. In addition, the first signal is used to prevent nonuniformity of wall charges caused by the use of the second reset signal.

FIG. 6 is a diagram for explaining the length of the flat period of the second reset signal and the length of the sustain period of the sustain signal.

Referring to FIG. 6, as shown in (a), the second reset signal RS2 includes a flat period M in which the maximum voltage of the rising ramp signal is maintained, and the sustain signal SUS gradually increases in voltage as shown in (b). It may include a rising period (d1) rising to, a sustaining period (d2) for maintaining the maximum voltage, and a falling period (d3) for the voltage to gradually fall.

In the sustain period, since a plurality of sustain signals are supplied, the length of the sustain period of one sustain signal is relatively short. On the other hand, since the rising ramp signal of the second reset signal has a relatively small maximum voltage, the length of the flat period of the second reset signal may be desirable to be relatively long. In consideration of this, it may be preferable that the length of the flat period of the second reset signal is longer than the length of the sustain period of the sustain signal.

The relationship between the length of the flat period of the second reset signal and the length of the sustain period of the sustain signal will be described with reference to Table 1 below.

Table 1

Table 1 observes the occurrence of erroneous discharge between 2 and 59 in the ratio (M / d2) of the length (M) of the flat period of the second reset signal and the length (d2) of the sustain period of the sustain signal. Predicted data.

When observing the occurrence of mis-discharge, many observers sensually evaluated whether bright spots were visible in a dark area of the screen while displaying an image of a window pattern on the screen in a dark room. Here, in the case where the bright spot is visible in the dark area of the screen, it was determined that the mis-discharge occurred.

In Table 1, the X marks are very poor due to excessive bright spots or lack of driving margin, and the ○ mark is relatively good, and the ◎ symbol is very good because the bright spot is sufficiently prevented and the driving margin is wide enough. Indicates.

Looking at Table 1, it can be seen that M / d2 is very poor in terms of bright spots when M / d2 is 2 or more and 3 or less.

The length M of the planar period M, which is M / d 2, greater than or equal to 2 and less than or equal to 3, may be excessively shorter than the length d 2 of the sustain period, so that the distribution of wall charges in the reset period of the second subfield may be uneven. . As a result, an incorrect discharge may occur such as an address discharge occurs in a discharge cell to which a data signal is not supplied, or a sustain discharge occurs in a discharge cell in which an address discharge does not occur. Therefore, the flashing bright spots can be seen in the dark area of the screen, which is bad in terms of mis-discharge.

When M / d2 is 5 or more and 9 or less, it can be seen that it is relatively good.

On the other hand, it can be seen that M / d2 is very good with 11 or more. This is because when M / d2 is 11 or more, the length M of the flat period can be sufficiently long, whereby the wall charge can be sufficiently uniform in the second reset period, so that the occurrence of erroneous discharge can be sufficiently prevented. .

On the other hand, in terms of driving margin, when the M / d2 is 2 or more and 29 or less, the length of the flat period may be sufficiently short. Accordingly, it is understood that the driving margin is very good by sufficiently securing the driving time.

In addition, it can be seen that when M / d2 is 32 or more and 52 or less.

On the other hand, when M / d2 is 59, it can be seen that it is very poor. This may be because the length of the flat period is excessively long, so that the driving time is insufficient, and thus the driving margin is excessively small.

6 and Table 1 above, it is preferable that the length M of the flat period of the second reset signal is not less than 5 times and not more than 52 times the length d2 of the sustain period of the sustain signal, more preferably. Preferably 11 times or more and 29 times or less.

7 is a view for explaining an example of another form of the second reset signal.

Referring to FIG. 7, the second reset signal includes an rising ramp signal that gradually rises from the voltage of the ground level GND to the first voltage V1 and a falling ramp signal that gradually descends from a voltage lower than the first voltage V1. It may include.

That is, the rate of change of the voltage of the rising ramp signal of the second signal can be kept substantially constant without changing while rising from the voltage at the ground level to the maximum voltage V1.

Also in this case, the length M of the flat period of the second reset signal may be preferably 5 times or more and 52 times or less than the length of the sustain period of the sustain signal, more preferably 11 times or more and 29 times or less. have. In this case, it may be preferable that the maximum voltage V1 of the second reset signal is substantially the same as or lower than the maximum voltage Vs of the sustain signal.

That is, when the maximum voltage V1 of the second reset signal is lower than or equal to the maximum voltage Vs of the sustain signal, the length of the flatness of the second reset signal is relatively long. The reason is that when the maximum voltage V1 of the second reset signal is lower than or equal to the maximum voltage Vs of the sustain signal, the intensity of the discharge generated by the second reset signal is relatively weakened, thereby improving the contrast characteristic. This is because the possibility of unstable distribution of wall charges can increase dramatically.

8 is a diagram for describing a driving signal that may be supplied to the sustain electrode in the setdown period.

Referring to FIG. 8, in the set down period of the reset period, the first sustain bias signal Vzb1 may be supplied to the sustain electrode. Then, the wall charges are more uniformly erased, so that the distribution of the wall charges can be made more uniform.

In the address period after the reset period, the second sustain bias signal Vzb2 may be supplied to the sustain electrode. This can reduce the interference by the sustain electrode in the address period and stabilize the address discharge.

The voltage of the first sustain bias signal Vzb1 and the voltage of the second sustain bias signal Vzb2 may be substantially the same as Vz.

In addition, the falling signal fs may be further supplied to the sustain electrode between the first sustain bias signal Vzb1 and the second sustain bias signal Vzb2. Then, the contrast characteristic can be improved by preventing the strong discharge from occurring at the end of the set-down period. The magnitude of the hourly voltage change rate of the falling signal may be substantially the same as the magnitude of the hourly voltage change rate of the falling ramp signal.

9 is a view for explaining the operation of the plasma display device according to another embodiment of the present invention.

9, in the reset period of the first subfield, the first reset signal RS1 may be supplied to the scan electrode Y, and the sustain period may be omitted after the reset period. That is, the sustain signal is not supplied in the first subfield.

As such, if the sustain signal is not supplied, smaller gray scales can be realized, and thus the gray scale power of the image can be improved. This is as follows.

For example, suppose that one sustain signal is supplied to each of the scan electrode and the sustain electrode in the sustain period of the first subfield. In such a case, gradation can be realized by summing light generated in the reset period, the address period, and the sustain period.

Here, assume that the gray scale of the light generated by one sustain signal is 0.5 gray and the gray scale of the light generated by the data signal and the scan signal is 0.5 gray. In addition, light generated in the reset period is ignored. This assumption is arbitrarily set for convenience of explanation.

In this case, if one wishes to implement a 0.5 gray scale image in a region consisting of nine discharge cells in total of 3 × 3, three discharge cells of nine discharge cells may be turned on.

Then, the gray level of the light generated in the region of nine discharge cells becomes 1.5 × 3, that is, 4.5 gray levels, and thus, the gray level of the image implemented by each of the nine discharge cells can be recognized as 0.5. In this method, the image quality of the image may be deteriorated such that a specific pattern is displayed on the screen.

On the other hand, when the sustain signal is not supplied, the gray level of the image that can be implemented by the first subfield is 0.5 gray level.

Therefore, if you want to implement a 0.5 grayscale image in a region consisting of nine discharge cells in total of 3 × 3, all nine discharge cells may be turned on. As a result, a specific pattern does not occur and thus the image quality of the image may be improved.

A plurality of reset signals may be supplied in the reset period of the second subfield which is continuous with the first subfield described above and later in time. For example, the first reset signal RS1 and the second reset signal RS2 may be supplied in the reset period of the second subfield.

As described above, the reason why the plurality of reset signals are supplied to the scan electrodes in the reset period of the second subfield is as follows.

In the first subfield preceding the second subfield, the sustain period is omitted or the sustain signal is not supplied, so the distribution of wall charges may be very unstable at the end of the first subfield.

For example, suppose that an address discharge occurs in the first discharge cell in the first subfield and no address discharge occurs in the second discharge cell.

In such a case, when the sustain signal is supplied to the first discharge cell, the wall charges are sufficiently accumulated so that the sustain discharge can be generated, and even if the sustain signal is supplied to the second discharge cell, the amount is small enough to not cause the sustain discharge. Wall charges remain.

Here, if the sustain signal is supplied to generate the sustain discharge, the distribution of the wall charges in the first discharge cell is shaken, so that a smooth reset can be performed in the subsequent reset period of the second subfield.

However, since the sustain signal is not supplied in the first subfield, the distribution of wall charges in the address period can be maintained until the reset period of the second subfield, which causes the wall charge between the first discharge cell and the second discharge cell. Due to this difference, the reset discharge of the second subfield may become unstable, and thus, the address discharge of the second subfield may become unstable.

On the other hand, when a plurality of reset signals are supplied to the scan electrodes in the reset period of the second subfield, the reset discharge can be stabilized and the distribution of the wall charges can be made uniform. Therefore, it is possible to reduce the difference between the wall charges of the first discharge cell and the second discharge cell and to stabilize the subsequent address discharge.

In the reset period of the third subfield continuous to the second subfield and disposed later in time, the reset signal of the form described in detail with reference to FIG. 7 may be supplied to the scan electrode.

In the reset period of the second subfield disposed before the third subfield, a plurality of reset signals are used to prevent nonuniformity of wall charges that may occur due to the sustain signal not being supplied in the first subfield. Then, the distribution of wall charges may be stable in the second subfield as a whole, and such a stable distribution of wall charges may be maintained until the reset period of the third subfield.

Therefore, in the reset period of the third subfield subsequent to the second subfield having a plurality of reset signals, the reset discharge does not suddenly become unstable even when the voltage of the reset signal is reduced, but rather, the amount of light generated by the reset discharge is reduced. The contrast characteristic can be improved.

Therefore, it may be desirable to use the reset signal as shown in FIG. 7 in the reset period in the third subfield subsequent to the second subfield.

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.

1 is a view for explaining the configuration of a plasma display device according to an embodiment of the present invention.

2 is a diagram for explaining the structure of a plasma display panel;

FIG. 3 is a diagram illustrating an image frame for implementing grayscale of an image in a plasma display device according to an embodiment of the present invention. FIG.

4 is a view for explaining an example of the operation of the plasma display device according to an embodiment of the present invention.

5 is a diagram for comparing a first reset signal and a second reset signal.

FIG. 6 is a diagram for explaining the length of the flat period of the second reset signal and the length of the sustain period of the sustain signal; FIG.

7 is a diagram for explaining an example of another form of the second reset signal.

8 is a diagram for explaining a drive signal that can be supplied to the sustain electrode in the setdown period.

9 is a view for explaining the operation of the plasma display device according to another embodiment of the present invention.

Claims (5)

A plasma display panel having parallel scan electrodes and sustain electrodes disposed thereon; A first reset signal is supplied to the scan electrode in a reset period of a first sub-field of a frame, and a second reset signal is supplied to the scan electrode in a reset period of a second subfield, The driver supplies a sustain signal to at least one of the scan electrode and the sustain electrode in the sustain period of the reset period of the second subfield. Including, Each of the first reset signal and the second reset signal includes a setup period in which a rising ramp signal in which the voltage gradually rises is supplied, a flat period in which the maximum voltage of the rising ramp signal is maintained, and a falling ramp signal in which the voltage gradually falls in the first reset signal and the second reset signal. Including the set-down period supplied, The sustain signal includes a rising period in which the voltage gradually rises, a sustaining period in which the maximum voltage is maintained, and a falling period in which the voltage gradually falls, The maximum voltage of the second reset signal is lower than the maximum voltage of the first reset signal, The length of the flat period of the second reset signal is longer than the length of the flat period of the first reset signal, And a flat period of the second reset signal is 5 to 52 times the length of the sustain period. The method of claim 1, And a flat period of the second reset signal is 11 to 29 times the length of the sustain period. The method of claim 1, And the second subfield is disposed backward in time relative to the first subfield. The method of claim 1, And a plurality of first reset signals. The method of claim 1, And the maximum voltage of the second reset signal is lower than or equal to the maximum voltage of the sustain signal.

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