KR20070072055A - Plasma display device and driving method the same - Google Patents

Abstract

A plasma display and a driving method thereof are provided to prevent erroneous discharge at a discharge cell by making the falling slope of a reset period smooth as external temperature increases and thus accurately initializing all discharge cells. A logic control unit(120) processes an image signal and outputs a predetermined logic signal. A scan driving unit(130) supplies a reset period having a rising period and a falling period of a predetermined slope to a scan electrode of a plasma display panel by the output signal of the logic control unit. An external temperature sensor(121) detects external temperature of the plasma display panel and supplies the detected temperature to the logic control unit. The logic control unit controls the scan driving unit to reduce the falling slope of the reset period as the external temperature obtained from the external temperature sensor increases.

Description

Plasma display device and driving method the same

1 is a partial perspective view showing an example of a plasma display panel of the plasma display device according to the present invention.

2 is a block diagram showing the electrical configuration of the plasma display device according to the present invention.

3 is a waveform diagram showing an example of driving waveforms in the plasma display device according to the present invention.

4A to 4C are waveform diagrams illustrating changes in a falling period of a reset period according to an external temperature rise among driving waveforms of the plasma display device according to the present invention.

FIG. 5 is a circuit diagram showing an example of a circuit for changing the falling period during the reset period in accordance with the temperature change in the plasma display device according to the present invention.

<Description of Symbols for Main Parts of Drawings>

10; Plasma display panel 11; Front board

12; Dielectric layer 13; Protective layer

14; Scan electrode 15; Holding electrode

16; Back substrate 17; Insulation layer

18; Address electrode 19; septum

20; Fluorescent layer 21; Discharge area

22; Discharge cell

100; Plasma display device according to the present invention

110; An image processor 120; Logic control

121; Temperature sensor 122; Memory

130; Scan driver 131; Falling Period Switching Section

132; Switching transistor 133; Time constant adjustment part

134; The gate driver 140; Retaining drive

150; Address driver

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device and a driving method thereof, and more particularly, to accurately initialize all discharge cells by changing the slope of a falling period during a reset period according to an external temperature change, thereby preventing erroneous discharge of discharge cells. The present invention relates to a plasma display device and a driving method thereof.

Plasma display device is the most suitable for large-sized flat panel display device in various fields such as liquid crystal display (LCD), field emission display (FED) and electroluminescence display (ELD), which are being actively studied. Have The reason why such a plasma display device can be enlarged as a flat plate is to form an electrode and a phosphor on each substrate by using two glass substrates each having a thickness of about 3 mm and forming a relatively less sophisticated printing (or deposition) method on the substrate. This is because a simple structure and method for forming plasma in space are adopted. That is, in the case of LCD, many transistors must be formed on a glass substrate by a high-precision thin film process, which causes a lot of difficulty in large-sized, and in the case of FED and ELD, since the commercialization has started, much research and development is still required.

In general, such a plasma display device displays 60 image frames per second, and the one frame is usually made of eight subfields and simultaneously displays 256 gray levels. Here, the one subfield is driven by being divided into a reset period, an address period, and a sustain period, wherein the reset period is a period for initializing all discharge cells, and the address period is selected by selecting discharge cells to be displayed in the plasma display panel. The sustain period is a period in which the discharge cells selected in the address period are discharged for a predetermined time to display an actual image.

In addition, the reset period is gradually fixed for a certain time so that, unlike the scan period provided during the address period and the sustain period provided during the sustain period, all the discharge cells are completely initialized and the wall charge distribution is uniform in all the discharge cells. There is an ascending rising period and a descent period that gradually descends for a period of time. This reset period is also commonly referred to as a lamp period. In particular, the falling period during the reset period serves to reduce the number of wall charges and to distribute the wall charges evenly in the discharge cells, so that the discharge occurs accurately during the next address period or the sustain period.

On the other hand, the conventional plasma display device is fixedly released so that the slope of the falling period during the reset period always has a constant value regardless of the external temperature. In one example, the slope of the falling period of the reset period is designed to have the most appropriate number and distribution of wall charges at room temperature (25 ℃).

However, when the plasma display device is in a high temperature state (for example, 40 ° C. to 60 ° C.), unlike at room temperature, a protective film (usually MgO), which is a component of the plasma display device, is formed on the surface of the dielectric layer covering the address electrode. Formed at the same time, prevents sputtering of the dielectric layer and at the same time serves to emit secondary electrons, so that the initialization of the discharge cells is not perfect, and the wall charges are not evenly distributed in the discharge cells. As a result, erroneous discharge occurs during the address period or the sustain period, which is the next driving period. That is, the protective film (MgO) changes the emission characteristics of the secondary electrons depending on the temperature, unlike at room temperature, when the high temperature state, the emission amount of the secondary electrons increases, so as to erase the wall charge as desired at room temperature As a result, the address discharge or sustain discharge in the next step is affected, resulting in an erroneous discharge phenomenon. In other words, conventionally, the slope of the falling period during the reset period is too steep, so that a strong discharge occurs, thereby causing a false discharge phenomenon.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned conventional problems, and an object of the present invention is to initialize all the discharge cells correctly by smoothing the slope of the falling period during the reset period as the external temperature increases, and thus The present invention provides a plasma display device and a driving method thereof that can prevent mis-discharge.

In order to achieve the above object, the present invention has a logic controller for processing a video signal and outputting a predetermined logic signal, and having a rising period and a falling period of a predetermined slope to the scan electrode of the plasma display panel by the output signal of the logic control unit. A scan driver for providing a reset period, and an external temperature sensor for sensing an external temperature of the plasma display panel and providing the logic controller to the logic controller, wherein the logic controller includes the scan driver as the temperature value obtained from the external temperature sensor increases; A plasma display apparatus is disclosed in which a control is performed to reduce a slope of a falling period during the reset period.

In addition, in order to achieve the above object, the present invention provides a method for driving a plasma display panel by applying a predetermined signal to the plasma display panel during a reset period, an address period and a sustain period, the method for sensing an external temperature of the plasma display panel; Disclosed is a driving method of a plasma display apparatus comprising an external temperature sensing step and a falling signal slope reducing step of decreasing a slope of a falling signal period during the reset period when the sensed external temperature increases.

As described above, the plasma display device and the driving method thereof according to the present invention provide sufficient wall charge erasing time by decreasing the slope of the falling period during the reset period (slowing down) as the external temperature increases.

In other words, according to the present invention, as the external temperature increases, the falling period of the reset period becomes longer (inversely, by shortening the holding time of Vnf applied after the falling period), so that the address in the next driving step due to the strong discharge is obtained. Prevent mis-discharge during periods or maintenance periods.

Of course, since the wall charges formed in one discharge cell are uniformly distributed throughout the cell region, it is natural that the address discharge and the sustain discharge are accurately made.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that those skilled in the art may easily implement the present invention.

1, an example of a plasma display panel of the plasma display device according to the present invention is shown as a perspective view.

As shown, the plasma display panel 10 may include a front substrate 11 and a back substrate 16. A plurality of scan electrodes 14 and sustain electrodes 15 are arranged on the front substrate 11 at predetermined intervals, and the surfaces of the front substrate 11 are sequentially covered by the dielectric layer 12 and the protective layer 13 (MgO). In addition, a plurality of address electrodes 18 are arranged in the rear substrate 16 in a direction perpendicular to the scan electrodes 14 and the sustain electrodes 15, and the surface of the back substrate 16 is covered by the insulating layer 17. In addition, a plurality of partitions 19 are arranged on the surface of the insulating layer 17 in a direction parallel to the address electrode 18 in a state in which a plurality of partitions 19 are spaced apart from each other by a predetermined distance. The G, B fluorescent layers 20 are each formed repeatedly. In this case, the discharge phenomenon is formed in a predetermined space 21 formed by the partition wall 19 and the passivation layer 13. In particular, the discharge phenomenon is one in a region where the scan electrode 14, the sustain electrode 15, and the address electrode 18 cross each other. Discharge cells 22 are formed.

Here, the plasma display panel 10 is only one example for understanding the present invention, and the present invention is not limited to the structure of the panel 10. For example, in the plasma display panel 10, the partition walls 19 are open at equal intervals, but the partition walls 19 may be formed in various shapes such as a closed type, a waffle type, and a honeycomb type. In addition, although only one fluorescent layer 20 is corresponded to one address electrode 18 in the panel 10, R, G, and B fluorescent layers 20 are respectively corresponded to one address electrode 18. It is also possible to make the structure correspond.

2, an electrical configuration of a plasma display device according to the present invention is shown as a block diagram.

First, as described above, in the plasma display panel 10, a plurality of scan electrodes 14 and sustain electrodes 15 are arranged in a horizontal direction, and a plurality of address electrodes 18 are arranged in the scan electrodes 14 and the sustain electrodes. It is arranged in the longitudinal direction to intersect with (15). Of course, one discharge cell 22 is formed in a region where the address electrode 18, the scan electrode 14, and the sustain electrode 15 cross each other.

Meanwhile, the plasma display apparatus 100 including the plasma display panel 10 includes an image processor 110, a logic controller 120, a scan driver 130, a sustain driver 140, and an address driver 150. can do. Furthermore, in the present invention, a temperature sensor 121 for sensing an external temperature is further connected to the logic controller 120, and a memory 122 storing slope data of a falling period during a reset period according to temperature is further connected. .

The image processor 110 converts an external image signal into an internal image signal that can be displayed on the plasma display panel 10 and outputs the converted image signal to the logic controller 120.

Then, the logic controller 120 outputs various control signals modified according to the internal image signal to the scan driver 130, the sustain driver 140, and the address driver 150. Here, the logic controller 120 outputs a control signal having different inclinations of different falling periods during the reset period to the scan driver 130 according to the external temperature sensed by the temperature sensor 121. Of course, since the slope data of the falling period according to the temperature is already stored in the memory 122, the logic controller 120 outputs a predetermined control signal to the scan driver 130 with reference to this.

Subsequently, the scan driver 130 receives the control signal of the logic controller 120 and outputs a predetermined driving signal to the scan electrode 14 of the plasma display panel 10 to implement the rising period and the falling period during the reset period. .

In addition, the sustain driver 140 receives a control signal from the logic controller 120 and outputs a predetermined sustain drive signal to the sustain electrode 15 during the sustain period.

In addition, the address driver 150 receives a control signal of the logic controller 120 and outputs a predetermined address driving signal for selecting the predetermined discharge cell 22 during the address period to the address electrode 18.

Referring to FIG. 3, an example of a driving waveform provided to a scan electrode, a sustain electrode, and an address electrode in the plasma display device according to the present invention is shown.

As illustrated, the plasma display apparatus 100 according to the present invention corresponds to a reset period, an address period, and a sustain period in one subfield through the scan electrode 14, the sustain electrode 15, and the address electrode 18. The predetermined signals are sequentially applied.

The reset period is mainly performed at the scan electrode 14, which is further divided into a rising period and a falling period. In the rising period, the voltage of the scan electrode 14 is increased with a predetermined slope from the voltage Vs to the voltage Vset while maintaining the address voltage at the reference voltage. Of course, at this time, a weak discharge occurs between the scan electrode 14 and the sustain electrode 15, the scan electrode 14, and the address electrode 18, and negative wall charges are applied to the scan electrode 14 and the sustain electrode 15. And the address electrode 18 are respectively formed with positive wall charges. At this time, all the discharge cells 22 are initialized because the voltage Vset is high enough to cause discharge in the discharge cells 22 under all conditions. Subsequently, in the falling period, the voltage of the scan electrode 14 is gradually decreased with the predetermined slope from the Vs voltage to the Vnf voltage while the address electrode 18 is maintained at the reference voltage. Of course, at this time, a weak discharge is generated between the scan electrode 14 and the sustain electrode 15, the scan electrode 14, and the address electrode 18. And the positive wall charges formed on the address electrode 18 are erased. In this case, the wall charge is not completely erased, and the number of the wall charges is uniformly distributed over the entire area of the discharge cell 22. In addition, the scan electrode 14 is maintained at the Vnf voltage for a predetermined time until the address period enters after the falling period, and this time is defined herein as the "hold time". This will be described in more detail below.

Next, in the address period, a scan pulse having VscL and an address pulse having a Va voltage are applied to the scan electrode 14 and the address electrode 18 to select the discharge cells 22 to be turned on. Of course, the unselected scan electrode 14 is biased to a VscH voltage higher than the VscL voltage, and a reference voltage is applied to the address electrode 18 of the discharge cell 22 that will not be turned on.

Finally, the sustain period is discharged for a predetermined time by alternately applying a voltage Vs having a 180 ° phase difference to the scan electrode 14 and the sustain electrode 15 corresponding to the selected discharge cell 22 during the address period. Of course, the plasma display panel 10 actually outputs a predetermined visible light screen during this holding period.

Here, the slope for the falling period during the reset period is designed to a value that allows the plasma display to operate best at room temperature (25 ° C). In other words, the voltage Vnf having a constant holding time until the entry of the address period after the falling period ends is applied, and the holding time is set to approximately 35 to 45 mA. This holding time is indicated by "t1" as in the figure. For reference, when the holding time is long, the falling period is short or the slope of the falling period is sharp, and if the holding time is short, the falling period is long or the slope of the falling period is that much. However, when the external temperature of the plasma display apparatus 100 increases as described in the related art, the slope of the falling period during the reset period is too rapid (the falling period is too short) so that the wall charges are completely erased or It is not initialized, and by generating a strong discharge, a false discharge is generated even in the following address period or sustain period. Therefore, in the present invention, as the external temperature of the plasma display apparatus 100 increases, the slope of the falling period becomes gentle (that is, the falling period becomes longer) during the reset period, thereby preventing the strong discharge and the following address. Do not discharge in the period or maintenance period.

4A to 4C, the change in the reset period according to the external temperature change among the driving waveforms of the plasma display device according to the present invention is shown as a waveform diagram.

4A is a reset period when the external temperature of the plasma display apparatus 100 is approximately 40 ° C, FIG. 4B is a reset period when the external temperature of the plasma display apparatus 100 is approximately 50 ° C, and FIG. 4C is a plasma The reset period when the external temperature of the display apparatus 100 is approximately 60 ° C is illustrated.

First, as shown in FIG. 4A, when the external temperature of the plasma display apparatus 100 is about 40 ° C., the holding time t2 is about 25 to 35 ms. In other words, when the external temperature is approximately 40 ° C., the slope of the falling period during the reset period becomes relatively smaller than that at normal temperature, that is, the time of the gentle or falling period is longer.

Subsequently, as shown in FIG. 4B, when the external temperature of the plasma display apparatus 100 is about 50 ° C., the holding time t3 is about 15 to about 25 ms. In other words, when the external temperature is approximately 50 ° C., the slope of the falling period during the reset period becomes relatively smaller than that of 40 ° C., that is, the time of the gentle or falling period is longer.

Finally, as shown in FIG. 4C, when the external temperature of the plasma display apparatus 100 is about 60 ° C., the holding time t4 is about 5 to 15 ms. In other words, when the external temperature is approximately 50 DEG C, the slope of the falling period during the reset period becomes relatively smaller, i.e., the time of the gentle or falling period becomes longer.

Here, the end time of the holding time t1, t2, t3, t4 or the time at which the voltage VscH starts to be applied is set equally in the collected temperature range in any case. Therefore, it should be noted that the calculation point of the holding time according to the temperature range is calculated inversely from the point at which the voltage VscH starts to be applied.

In this manner, in the present invention, even when the external temperature of the plasma display panel 10 reaches approximately 40 ° C. to 60 ° C., no strong discharge occurs during the falling period, and the wall charge erase time is sufficient, so that the discharge cells 22 The wall charges are uniformly distributed in all areas of).

Referring to FIG. 5, an example of a circuit for changing a falling period of a reset period according to a temperature change in a plasma display device according to the present invention is shown.

As shown in the present invention, the falling period switching unit 131 may be installed in the scan driver 130 to provide the falling period to the scan electrode 14 during the reset period. The falling period switching unit 131 may include a falling power supply V_ramp, a switching transistor 132, a time constant adjusting unit 133, and a gate driver 134. In the drawing, the plasma display panel 10 is equivalent to the panel capacitor Cp.

The switching transistor 132 has a drain connected to the falling power supply V-ramp and a source connected to the panel capacitor Cp. The switching transistor 132 may be a general power field effect transistor, but the type is not limited thereto.

The time constant adjusting unit 133 is connected between the gate and the drain of the switching transistor 132 to adjust the slope or holding time t1, t2, t3, t4 of the falling period signal. That is, as described above, the time constant adjusting unit 133 maintains the holding time at 35 ° C. to 45 ° C. when the external temperature is 25 ° C., and maintains the holding time at 25 ° C. to 35 ° C. when the external temperature is 40 ° C., If the external temperature is 50 ℃, the holding time is 15 ~ 25㎲, and if the external temperature is 60 ℃, the holding time is 5 ~ 15㎲. In addition, the time constant adjusting unit 133 may be determined as a resistor R and a capacitor C as known. Here, an example of adjusting the time constant by forming the resistors R1, R2, and R3 in addition to the resistor R is shown. Of course, the time constant may be adjusted by further connecting another capacitor in addition to the capacitor C. Here, the resistor R and the resistors R1, R2, and R3 are all connected in series, and a switch formed in the gate driver 134 to be performed between the resistor R and the resistor R1, the resistor R1 and the resistor R2, and the resistor R2 and the resistor R3. It is connected to S1, S2, S3, and S4. Of course, even when the resistors R, R1, R2, and R3 are connected in series, the resistance value is designed so that the switching transistor 132 has a gate voltage that can be sufficiently driven.

The gate driver 134 is connected between the time constant adjusting unit 133 and the source of the switching transistor 132 to control the switching transistor 132 to a predetermined time constant.

For example, the gate driver 134 installed in the scan driver 130 may close the switch S1 when the logic controller 120 recognizes the external temperature as a room temperature (25 ° C.) and outputs a predetermined control signal. . Of course, the switch S2 to switch S4 is to be opened at this time. Then, the switching transistor 132 is operated with a time constant determined by the resistor R and the capacitor C, and thus the slope of the falling period is the steepest or the falling period is shortest. That is, the holding time t1 is set to approximately 35 to 45 ms.

In addition, when the logic controller 120 recognizes an external temperature of about 40 ° C. and outputs a predetermined control signal, the gate driver 134 closes the switch S2. Of course, the switch S1 and the switches S3, S4 are to be opened. Then, the switching transistor 132 is operated with a time constant determined by the resistors R, R1, and the capacitor C, and thus the slope of the falling period is slightly slower or slightly longer than when the room temperature is at room temperature. That is, the holding time t2 is set to approximately 25 to 35 ms.

In addition, when the logic controller 120 recognizes the external temperature as approximately 50 ° C. and outputs a predetermined control signal, the gate driver 134 closes the switch S3. Of course, at this time, the switches S1, S2, S4 are to be opened. Then, the switching transistor 132 is operated with a time constant determined by the resistors R, R1, R2 and capacitor C, so that the slope of the above falling period is gentler or the falling period is longer than when 40 ° C. do. That is, the holding time t3 is set to approximately 15 to 25 ms.

Finally, when the logic controller 120 recognizes the external temperature as approximately 60 ° C. and outputs a predetermined control signal, the gate driver 134 closes the switch S4. Of course, at this time, the switches S1 to S3 are to be opened. Then, the switching transistor 132 is operated with a time constant determined by the resistors R, R1, R2, R3 and capacitor C, so that the slope of the above falling period is more gentle or the falling period is longer than 50 ° C. It will be the longest. That is, the holding time t4 is set to approximately 5 to 15 ms.

In this way, the present invention allows the wall display to be sufficiently erased by slowly or gradually decreasing the slope of the falling period during the reset period by the scan electrode 14 as the external temperature of the plasma display apparatus 100 increases. do. In other words, of course, the holding time is shortened as the external temperature increases, and conversely, the wall charge erasing time is correspondingly longer. Therefore, the wall charges in the discharge cells 22 are more uniformly distributed, and thus, erroneous discharges are prevented in subsequent address periods and sustain periods.

As described above, the plasma display device and the driving method thereof according to the present invention provide sufficient wall charge erasing time by decreasing the slope of the falling period during the reset period (slowing down) as the external temperature increases.

In other words, according to the present invention, as the external temperature increases, the falling period of the reset period becomes longer (inversely, by shortening the holding time of Vnf applied after the falling period), so that the address in the next driving step due to the strong discharge is obtained. Prevent mis-discharge during periods or maintenance periods.

Of course, since the wall charges formed in one discharge cell are uniformly distributed throughout the cell region, it is natural that the address discharge and the sustain discharge are accurately made.

What has been described above is only one embodiment for implementing the plasma display device and the driving method thereof according to the present invention, and the present invention is not limited to the above-described embodiment, as claimed in the following claims. Without departing from the gist of the invention, anyone of ordinary skill in the art to which the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

Claims (8)

A logic controller which processes a video signal and outputs a predetermined logic signal; A scan driver for providing a scan period of the plasma display panel with a reset period having a rising period and a falling period of a predetermined slope by an output signal of the logic controller; An external temperature sensor that senses an external temperature of the plasma display panel and provides the logic controller to the logic controller; And the logic controller controls the scan driver to decrease the slope of the falling period during the reset period as the temperature value obtained from the external temperature sensor increases. The plasma display apparatus of claim 1, wherein a memory is further installed in the logic controller, and data is stored in the memory to decrease a slope value of the falling period as an external temperature increases. 2. The plasma display apparatus of claim 1, wherein the scan driver applies a low voltage for a predetermined time until a address period after a reset period, and the low voltage holding time is controlled to decrease as the external temperature increases. The method of claim 3, wherein the low voltage holding time is 35 to 45 kV when the external temperature is 25 ° C, 25 to 35 kV when the external temperature is 40 ° C, and 15 to 25 kV when the external temperature is 50 ° C, Plasma display device, characterized in that 5 ~ 15㎲ when the external temperature is 60 ℃. The switching transistor of claim 1, wherein the scan driver is provided with a falling period switching unit for providing a falling period, the falling period switching unit being connected to a falling voltage to output a falling period signal to a plasma display panel; A time constant adjuster connected between the gate and the drain of the transistor to adjust the slope of the falling period signal, and a gate driver connected to the gate of the switching transistor to apply a gate voltage and simultaneously control the time constant adjuster. Plasma display device, characterized in that. A method of driving a plasma display panel by applying a predetermined signal to the plasma display panel during a reset period, an address period, and a sustain period, An external temperature sensing step of sensing an external temperature of the plasma display panel; And decreasing the slope of the falling signal to decrease the slope of the falling signal period during the reset period when the sensed external temperature increases. 7. The method of claim 6, wherein a low voltage holding time for applying a low voltage for a predetermined time exists between the reset period and the address period, and the low voltage holding time is shortened as the external temperature of the plasma display panel increases. A method of driving a plasma display device. According to claim 7, wherein the low voltage holding time is 35 ~ 45㎲ when the external temperature is 25 ℃, 25 ~ 35㎲ when the external temperature is 40 ℃, 15 ~ 25㎲ when the external temperature is 50 ℃, When the external temperature is 60 ℃ drive method of the plasma display device, characterized in that 5 ~ 15㎲.

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