JP4165051B2 - Plasma display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display device.
[0002]
[Prior art]
In a conventional AC discharge type plasma display device, an ultraviolet ray generated by discharge is converted into visible light to light a cell constituting a pixel and display an image.
[0003]
For general AC discharge type plasma display device will be described with reference to the drawings of FIGS.
[0004]
Figure 3 is a diagram showing a general AC discharge structure of the plasma display device panel, as shown in FIG. 3, the scan side electrode 2 on the surface of the front plate 1, the sustain-side electrode 3, the dielectric 4 and protective A film 5 is disposed, and a data side electrode 7, a dielectric 8, a cell partition wall 9 and a phosphor 10 are disposed on the surface of the back plate 6. The front plate 1 and the back plate 6 are arranged to face each other so that the scan side electrode 2, the sustain side electrode 3 and the data side electrode 7 are substantially orthogonal to each other, and the peripheral portion is sealed. It is comprised by enclosing.
[0005]
In this AC discharge type plasma display device, gradation expression is performed by dividing one frame of video into a plurality of subfields. In order to further control the discharge in the panel, one subfield is further divided into four periods. is doing. These four periods will be described with reference to FIG .
[0006]
FIG. 4 is a diagram showing a driving voltage waveform of a general conventional AC discharge type plasma display device. In the setup period A, in order to easily generate discharge, a pulse Pst is applied to perform discharge and the vicinity of the electrodes of all cells. Charge (wall charge). In the address period B, the voltage generated by the wall charges accumulated earlier and the forward voltage are applied to each electrode to perform address discharge. In practice, the scan discharge Pscn is applied to the scan side electrode 2 which is the row electrode of the line to be written, and simultaneously, the write discharge is performed by applying the write pulse Pw to the data side electrode 7 of the cell.
[0007]
In the sustain period C, the sustain pulse Psus is applied to light the cells written in the address period B and maintain the lighting. In the erase period D, the erase pulse Pe is applied, and the wall charge is erased to stop the lighting of the cell.
[0008]
FIG. 5 is a diagram showing the overall configuration of this AC discharge type plasma display device . In FIG. 5 , the input signal is input to the video signal processing unit 21 and converted into a video signal suitable for the plasma display, and the data side driving unit. 22 is output. The input signal is also input to the synchronization signal separation unit 23 where the synchronization pulse is separated. The separated sync pulse is sent to the timing pulse generator 24 connected to the output unit of the sync signal separator 23. The output terminals of the timing pulse generator 24 are connected to the input terminals of the video signal processor 21, the data side driver 22, the scan side driver 25, the sustain side driver 26, and the scan pulse generator 27, respectively. To control the output timing. Further, the output of the scan side drive unit 25 is input to the scan pulse generation unit 27, and the scan pulse is superimposed on the waveform output from the scan side drive unit 25.
[0009]
The output of the data side drive unit 22 is connected to m data side electrodes 29 arranged in the column direction on the plasma display panel 28, and the output of the scan pulse generation unit 27 is in the row direction orthogonal to the data side electrode 29. Are connected to n scan-side electrodes 30, and the output of the sustain-side drive unit 26 is connected to n sustain-side electrodes 31 arranged in parallel to the scan-side electrode 30, and each drive unit and The scanning pulse generator 27 controls the voltage applied to each electrode to perform lighting display of each cell of the plasma display panel 28.
[0010]
[Problems to be solved by the invention]
In such a plasma display device, there is a problem that when the panel temperature rises or when the panel is lit for a long time, the discharge is not stably performed and the display lighting state is remarkably deteriorated.
[0011]
When the panel temperature rises, impurities in the phosphor are vaporized by the temperature rise and mixed into the discharge gas. At this time, since the number of molecules in the discharge gas increases, the probability of collision with electrons in the discharge gas increases. The collision between the molecule and the electron is excited by the collision of the molecule and the electron, and the electron generated at that time collides with the other molecule and excites it. Then, discharge is promoted.
[0012]
In the address period B, writing is performed by sequentially applying the scan pulse Pscn to the scan side electrode 30, but the voltage Vscn is applied to the scan side electrode 30 where writing is not performed, and electrons resulting from the occurrence of discharge are scanned side electrode 30. Accumulate nearby. However, it is impossible to maintain a state where all electrons are accumulated, and a few electrons are emitted into the discharge gas. When the number of molecules in the discharge gas increases as the panel temperature rises and discharge is likely to occur, molecules are excited by slightly emitted electrons, causing unnecessary discharge and degrading the display lighting state.
[0013]
In addition, when the panel is lit for a long time, the protective film is sputtered by the discharge during lighting. At this time, impurities in the protective film are released into the discharge gas. This leads to an increase in the number of molecules in the discharge gas, as in the case of the rise in the panel temperature described above, so that a discharge is likely to occur, and an unnecessary discharge is caused by slightly emitted electrons, degrading the display lighting state. .
[0014]
The present invention has been made in view of such problems, and an object of the present invention is to suppress the deterioration of the display lighting state even when the panel temperature rises or when the panel is lit for a long time.
[0015]
[Means for Solving the Problems]
In order to solve such a problem, the present invention applies a scan pulse to a plurality of row electrodes and applies a write pulse to a plurality of column electrodes orthogonal to the row electrodes in accordance with display data. A plasma display device having a writing period for selecting on / off, wherein a voltage applied to the row electrode during the writing period changes with a cumulative lighting time of the panel except for a scanning pulse application time. It is comprised so that it may make it.
[0016]
Further, the plasma display device of the present invention includes a cumulative lighting time calculation unit that calculates a cumulative lighting time based on a video signal input from the outside and generates a signal corresponding to the cumulative lighting time, and the cumulative lighting time calculation unit. And a voltage level controller for changing the voltage applied to the row electrode in accordance with the output signal.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
That is, in the plasma display device of the present invention is obtained by constituting the voltage Vscn applied to the row electrodes during the write period excluding the time of scanning pulse is applied so as to vary with the cumulative lighting time, long time, the panel When is turned on , deterioration of the display lighting state can be prevented by increasing the voltage Vscn.
[0018]
Hereinafter, FIG. 1 for a plasma display apparatus according to an embodiment of the present invention will be described with reference to FIG. In addition, the same number is attached | subjected about the same part as the part shown in FIGS .
[0019]
FIG. 1 shows voltage waveforms applied to the respective electrodes in the present invention. The setup period A, the sustain period C, and the erase period D are the same as those in the conventional driving method. In the address period B, the scan pulse Pscn is sequentially applied to the scan side electrode 30 which is the row electrode of the line to be written, and at the same time, the write pulse Pw is applied to the data side electrode 29 of the cell to perform the write discharge. A voltage Vscn is applied to the scan-side electrode 30 on which no writing is performed, and electrons resulting from the occurrence of discharge are accumulated near the scan-side electrode 30.
[0020]
Here, when the panel temperature rises or when the panel is lit for a long time, discharge is generated only by the release of a few electrons into the discharge gas due to impurities mixed in the discharge gas. Therefore, by increasing the voltage Vscn applied to the scan side electrode 30 during the writing period except when the scan pulse is applied, electrons can be accumulated in the vicinity of the scan side electrode 30 to suppress the number of electrons emitted to the discharge gas. it can.
[0021]
Therefore, when the panel is lit for a long time, the display lighting state can be prevented from deteriorating by increasing the voltage Vscn.
[0022]
If the voltage Vscn is constantly maintained at a high voltage, the power consumed when the scan pulse Pscn is applied to the scan side electrode 30 increases. Changing the voltage Vscn with the cumulative time that the panel is lit in order to reduce the power consumption (accumulated lighting time). That is, an increase in unnecessary power consumption can be suppressed by increasing the voltage Vscn only when the panel is lit for a long time .
[0023]
FIG. 2 is a diagram showing an example of the overall configuration of the plasma display device of the present invention.
[0024]
In FIG. 2, the difference from the configuration of the conventional plasma display device is that a cumulative lighting time calculation unit 43 that calculates a cumulative lighting time from an input video signal and generates a signal corresponding thereto is provided, and according to the output signal, This is because the changed voltage Vscn is output from the scan pulse generator 27.
[0025]
In FIG. 2 , an input signal is input to the video signal processing unit 21, converted into a video signal suitable for a plasma display, and output to the data side driving unit 22 and the cumulative lighting time calculation unit 43. The cumulative lighting time calculation unit 43 calculates the cumulative lighting time by integrating the signal from the video signal processing unit 21. A signal corresponding to the calculation result is input to the voltage level control unit 42, and the output voltage of the voltage level control unit 42 is changed according to the signal . By inputting the output voltage to the scan pulse generator 27, the voltage Vscn applied to the scan side electrode 30 is changed.
[0026]
With this circuit configuration, the display lighting state can be prevented from deteriorating by increasing the voltage Vscn when the panel is lit for a long time.
[0027]
【The invention's effect】
As described above, according to the present invention, the voltage applied to the row electrode is changed with the cumulative lighting time during the writing period except when the scan pulse is applied, and according to the cumulative lighting time. By increasing the voltage, deterioration of the display lighting state can be prevented.
[Brief description of the drawings]
FIG. 1 is a signal waveform diagram showing a voltage waveform applied to each electrode of a plasma display device according to an embodiment of the present invention. FIG. 2 is a block diagram showing an overall configuration of a plasma display device according to the present invention. FIG . 4 is a schematic perspective view showing a panel structure of a general AC discharge type plasma display device. FIG . 4 is a signal waveform diagram showing a voltage waveform applied to each electrode of the plasma display device . Block diagram showing [Description of symbols]
DESCRIPTION OF SYMBOLS 22 Data side drive part 25 Scan side drive part 27 Scan pulse generation part 28 Plasma display panel 29 Data side electrode 30 Scan side electrode 42 Voltage level control part 43 Cumulative lighting time calculation part

Claims (3)

  A plasma display device having a writing period in which a scanning pulse is applied to a plurality of row electrodes and a writing pulse is applied to a plurality of column electrodes orthogonal to the row electrodes in accordance with display data to select lighting / extinguishing of pixels. In the plasma display device, the voltage applied to the row electrode during the writing period is changed with the cumulative lighting time of the panel except for the time when the scan pulse is applied.   The plasma display device according to claim 1, wherein the voltage applied to the row electrode is increased when the cumulative lighting time is increased.   A cumulative lighting time calculation unit that calculates a cumulative lighting time based on a video signal input from the outside and generates a signal corresponding to the cumulative lighting time, and a voltage that is applied to the row electrode according to an output signal of the cumulative lighting time calculation unit The plasma display device according to claim 1, further comprising a voltage level control unit that changes the voltage.

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