JP4703042B2 - Plasma display panel drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display panel driving apparatus for driving a plasma display panel, and more particularly to a plasma display panel driving apparatus capable of appropriately controlling the number of sustain pulses.
[0002]
[Prior art]
In the plasma display panel, the display brightness is controlled for the purpose of appropriately managing the panel life and suppressing the heat generation of the driver. That is, as shown in FIG. 6, in the region where the average luminance level (APL) of the plasma display panel is a predetermined value or more, as the average luminance level increases, the number of sustain pulses in one field, that is, in each subfield. The brightness level is limited by gradually decreasing the total number of sustain pulses. On the other hand, in the region where the average luminance level is equal to or lower than the predetermined value, the number of pulses in one field is set to a constant value without limiting the number of pulses of the sustain pulse.
[0003]
[Problems to be solved by the invention]
However, as shown in FIG. 6, when the number of sustain pulses in one field is constant in a region below the average luminance level, there is a problem that the peak luminance in the low luminance part in that region is insufficient.
[0004]
An object of the present invention is to provide a plasma display panel driving device capable of appropriately limiting the number of sustain pulses without causing peak luminance to be insufficient in a low luminance portion.
[0005]
[Means for Solving the Problems]
The plasma display panel driving apparatus of the present invention includes a selection means (7 etc.) for selecting a light emitting cell, and a sustain pulse output means (8) for outputting a sustain pulse for repeatedly emitting light from the light emitting cell selected by the selection means (7 etc.). , 9) and the sustain pulse of each subfield output from the sustain pulse output means (8, 9) according to the average luminance level when the average luminance level of the display on the plasma display panel (20) is a predetermined value or more. Sustain pulse limiting means (4, 5) for limiting the number of pulses, and the sustain pulse limiting means (4, 5) has a constant number of pulses in the first low luminance region where the average luminance level is a predetermined value or less. And the number of pulses is increased in the second low-brightness region having an average luminance level lower than that in the first low-brightness region, compared with the first low-brightness region It was, in the low luminance area average luminance level is lower third than the second low luminance regions and decreases the number of pulses so as to have a region lower pulse number than the first low brightness area .
[0006]
According to this plasma display panel driving apparatus, by making the number of sustain pulses constant in the first low luminance region, it is possible to suppress the heat generation of the sustain pulse output means and extend the life of the plasma display panel. Further, the peak luminance can be increased by increasing the number of sustain pulses in the second low luminance region. Further, by reducing the number of sustain pulses so that the third low luminance region has a lower number of pulses than the first low luminance region, the sustain pulse output means without causing display problems In addition, the life of the plasma display panel can be extended.
[0007]
A fourth low luminance region in which the number of pulses is constant may be provided between the second low luminance region and the third low luminance region.
[0008]
In this case, by providing the fourth low luminance region between the second low luminance region and the third low luminance region, the third low luminance region is limited to an area very close to the black level. For this reason, display problems do not occur even if the number of sustain pulses is decreased in the third low luminance region.
[0009]
In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are added in parentheses, but the present invention is not limited to the illustrated embodiments.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a panel driving device according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a panel driving apparatus of this embodiment, FIG. 2 is a diagram showing a driving sequence in one field period, and FIG. 3 is a diagram showing driving waveforms in one subfield.
[0011]
As shown in FIG. 1, the panel drive device 100 of this embodiment includes an A / D converter 1 that converts an analog video signal into input image data, and display data based on an output signal from the A / D converter 1. Display data generation unit 2 to be generated, memory 3 that sequentially stores display data output from display data generation unit 2, and average luminance that detects an average luminance level based on an output signal from A / D converter 1 A level detection unit 4 and a control unit 5 that receives the average luminance level detected by the average luminance level detection unit 4 are provided.
[0012]
In addition, the panel driving apparatus 100 includes an address driver 7 that drives the column electrodes D1 to Dn of the plasma display panel 20, a sustain driver 8 that simultaneously applies X sustain pulses to the sustain electrodes X1 to Xn of the plasma display panel 20, and Y And a sustain driver 9 for simultaneously applying a sustain pulse to the sustain electrodes Y1 to Yn of the plasma display panel 20.
[0013]
As shown in FIG. 1, the output data from the memory 3 is given to the address driver 7. The control unit 5 controls the sustain driver 8 and the sustain driver 9 based on the average luminance level.
[0014]
Next, the operation of the panel driving apparatus 100 will be described with reference to FIGS.
[0015]
As shown in FIG. 2, the display period of one field in the panel drive device 100 is composed of six subfields SF1 to SF6. The display data is 6 bits, and the subfields SF1 to SF6 are weighted corresponding to the bits of each bit digit. Thereby, gradation display on the plasma display panel 20 is possible.
[0016]
As shown in FIG. 2, in each of the subfields SF1 to SF6, a reset period for eliminating the influence of the immediately preceding subfield, an address period for setting a lighting cell by forming wall charges, and an address A sustain period for repeating light emission of the lighting cell set in the period is provided. The subfield SF6 is provided with a main erase period for initializing wall charges of all the discharge cells after the sustain period. A weight indicated by k1 to k6 (where k1 + k2 + k3 + k4 + k5 + k6 = 1) is given to the sustain period of each subfield, and the number of sustain pulses corresponding to k1 to k6 is set in each sustain period.
[0017]
As shown in FIG. 3, the panel driving apparatus of this embodiment employs a driving method based on a selective erasure address method.
[0018]
As shown in FIG. 3, in the reset period of each of the subfields SF1 to SF6, the negative reset pulse RPx is applied to all the row electrodes X1 to Xn, and the positive reset pulse RPy is applied to all the row electrodes Y1 to Yn. Applied simultaneously. As a result, a reset discharge is simultaneously generated between the pair of row electrodes X and Y constituting the display line, that is, in all the discharge cells, and wall charges are formed in all the discharge cells after the discharge is completed.
[0019]
On the other hand, as shown in FIG. 1, the input video signal input to the A / D converter 1 is converted by the A / D converter 1 into, for example, 8-bit data GD. The data GD is subjected to a 2-bit compression process (error diffusion process or dither process) by the display data generation unit 2, converted into 6-bit display data HD, and written into the memory 3. The display data HD stored in the memory 3 is read for each corresponding bit data in the address period of each of the subfields SF1 to SF6 and supplied to the address driver 7.
[0020]
In the address period, the scan pulse SP is sequentially applied to one (Y electrode) of the row electrode pair for each display line. Further, in synchronization with the application of the scan pulse SP, the address driver 7 applies a data pulse for one line corresponding to the line to the column electrodes D1 to Dm. The data pulse is not output when the discharge cell is turned on, but is output when the discharge cell is turned off. In the cell to which the data pulse is supplied in synchronization with the scan pulse, selective erasing discharge occurs, the wall charge formed in the reset period disappears, and the cell is set as an extinguished cell. On the other hand, in a cell to which no data pulse is supplied in synchronization with the scan pulse, discharge does not occur, wall charges formed during the reset period remain, and the cell is set as a lighted cell.
[0021]
After the selection operation for the display line is completed, a sustain period is started, and a sustain pulse having the number of pulses corresponding to the weight of the subfield is applied to the row electrodes X and Y. In the sustain period, in the discharge cell in the lighting cell state in which the wall charges remain, the sustain discharge light emission occurs every time the sustain pulse is applied. On the other hand, in a discharge cell in an extinguished cell state in which wall charges have disappeared, no discharge occurs even when a sustain pulse is applied.
[0022]
The gradation display is executed by repeatedly performing one subfield driving process including the reset period, the address period, and the sustain period in each of the subfields SF1 to SF6.
[0023]
FIG. 4 is a diagram showing the relationship between the average luminance level and the number of sustain pulses, and FIG. 5 is a partial enlarged view of FIG. 4 (enlarged view of the portion indicated by symbol A).
[0024]
As shown in FIG. 1, the number of sustain pulses in the sustain period is controlled by the control unit 5 controlling the sustain driver 8 and the sustain driver 9 based on the average luminance level detected by the average luminance level detection unit 4. Is executed.
[0025]
4 and 5 show the total number of sustain pulses in all subfields belonging to one field. In the panel drive device of the present embodiment, the total number of pulses in one field changes according to the average luminance level, but the above weighting of the number of sustain pulses set for each field is unchanged. .
[0026]
As shown in FIGS. 4 and 5, in the panel drive device of this embodiment, the number of sustain pulses is constant in the first low luminance region where the average luminance level is a predetermined value or less. This is because the number of sustain pulses is made constant in consideration of heat generation of the sustain driver 8 and the sustain driver 9 in a region where the average luminance level is relatively high even in a region where the average luminance level is a predetermined value or less.
[0027]
Further, in the second low luminance region where the average luminance level is lower than that of the first low luminance region, the number of sustain pulses is increased as compared with the first low luminance region. This is intended to increase the peak luminance by increasing the number of sustain pulses in the low luminance region. Thereby, sufficient peak luminance can be maintained in a low luminance region, and visibility can be improved.
[0028]
Further, the number of sustain pulses is reduced in the third low luminance region having an average luminance level lower than that of the second low luminance region, compared to the first low luminance region. When the average luminance is extremely small as in the third low luminance region, it is no longer necessary to increase the peak luminance from the viewpoint of display. In addition, since the frequency when the average luminance level is in the third low luminance region is high, such as when no video signal is input, the effect of reducing the number of sustain pulses is also high. For this reason, in the third low-luminance region, the number of sustain pulses is reduced to reduce the heat generation of the sustain driver 8 and the sustain driver 9.
[0029]
In addition, a fourth low luminance region in which the number of sustain pulses is constant is provided between the second low luminance region and the third low luminance region. For this reason, the third low luminance area is limited to an area that is extremely close to the black level. Therefore, even if the number of sustain pulses is decreased in the third low luminance area, display problems do not occur.
[0030]
As shown in FIGS. 4 to 6, the graph (FIG. 4) showing the number of sustain pulses in the related art has one inflection point, whereas in this embodiment, there are a plurality of inflection points ( 4 places).
[0031]
【The invention's effect】
As described above, according to the plasma display panel driving apparatus of the present invention, the number of sustain pulses is made constant in the first low luminance region, thereby suppressing the heat generation of the sustain pulse output means and the plasma display panel. Can extend the lifespan. Further, the peak luminance can be increased by increasing the number of sustain pulses in the second low luminance region. Further, by reducing the number of sustain pulses so that the third low luminance region has a lower number of pulses than the first low luminance region, the sustain pulse output means without causing display problems In addition, the life of the plasma display panel can be extended.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a panel drive device of an embodiment.
FIG. 2 is a diagram showing a driving sequence in one field period.
FIG. 3 is a diagram showing a driving waveform in one subfield.
FIG. 4 is a diagram showing a relationship between an average luminance level and the number of sustain pulses.
5 is a partially enlarged view of FIG. 4;
FIG. 6 is a diagram showing a conventional apparatus.
[Explanation of symbols]
4 Average luminance level detector (sustain pulse limiting means)
5 Control unit (sustain pulse limiting means)
7 Address driver 8 Sustain driver (sustain pulse output means)
9 Sustain driver (sustain pulse output means)
20 Plasma display panel

Claims (2)

A selection means for selecting a light emitting cell;
A sustain pulse output means for outputting a sustain pulse for repeatedly emitting light from the light emitting cell selected by the selection means;
A sustain pulse limiting means for limiting the number of sustain pulses of each subfield output from the sustain pulse output means according to the average brightness level when the average brightness level of display in the plasma display panel is a predetermined value or more; ,
With
The sustain pulse limiting means is
In the first low luminance region where the average luminance level is a predetermined value or less, the number of pulses is made constant,
In the second low-brightness region having an average luminance level lower than that of the first low-brightness region, the number of pulses is increased as compared with the first low-brightness region,
The third low-brightness region having an average luminance level lower than that of the second low-brightness region is characterized in that the number of pulses is reduced so that the number of pulses is lower than that of the first low-brightness region. A plasma display panel driving device. 2. The plasma display according to claim 1, wherein a fourth low luminance region in which the number of pulses is constant is provided between the second low luminance region and the third low luminance region. Panel drive device.

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