JPH11296137A - Method and device for driving plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method and the device for driving a plasma display panel(PDP) in which the contrast is made higher and the writing discharge malfunction is reduced in all gradation. SOLUTION: In a display field DF1, a subfield SF1 starts from a pilot fire interval 611 and continues to an erasing interval 621, a writing interval 631 and a maintaining interval 641. On the other hand, in subfields SF2 to SF4, no pilot fire interval is provided and a start is made with the erasing interval 621. In this driving method, the number of the subfields having pilot fire intervals among plural subfields is set to be less than the total number of plural subfields in one display field a pilot fire interval is set in any subfield among any one of plural continuous display fields. Thus, the presence of the display cell, which always becomes a discharge fail, is eliminated, even though there exists the display cell, which becomes harder to discharge, if no pilot fire discharge is conducted and no irregularity exists in the picture because no discharge failure display cell exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for driving a plasma display panel, and more particularly to a method and an apparatus for driving a plasma display panel in which the number of pilot discharges is reduced.

[0002]

2. Description of the Related Art Generally, a plasma display panel displays images and information by using visible light obtained by exciting a phosphor with ultraviolet rays generated by gas discharge. The plasma display panel is classified into an AC type and a DC type according to the driving method. In the following description, an AC three-electrode surface discharge type plasma display panel will be described as an example.

FIG. 10 is a perspective view (partially a sectional view) showing a sectional structure of an AC three-electrode surface discharge type plasma display panel.
Indicated by However, in FIG. 10, for convenience of description, the substrates 410 and 420 are shown in a state where they are opened in the vertical direction.

In FIG. 10, a strip-shaped transparent electrode 411 is used as a scanning and sustaining electrode for performing surface discharge on a front substrate 410.
a and 411b are formed. The transparent electrodes 411a and 411b are usually formed of ITO (Indium Tin Oxide) or SnO ₂ . However, since the transparent electrodes 411a and 411b have high sheet resistance, the transparent electrodes 411a and 411b have a high sheet resistance.
The bus electrodes 412a and 412b are formed along the lines a and 411b with a thick silver film having a lower sheet resistance than the transparent electrodes 411a and 411b. Further, a (transparent) dielectric layer 413 made of low melting point glass or the like is formed thereon. The dielectric layer 413 is a protective layer 41 made of MgO.
4. The protective layer 414 is made of the dielectric 41
3 is a portion that not only has a protective effect, but also has a secondary electron emitting effect and a wall charge accumulating effect at the time of gas discharge.

[0005] On the rear substrate 420, a band-shaped data electrode 4 is provided.
21 is formed of a thick silver film or the like, and partition walls 4 for separating display pixels are formed.
22 is formed of low melting point glass or the like along the data electrode 421. Further, a phosphor 423 that emits visible light is applied to a portion separated by the partition 422.

The front substrate 410 thus formed
And rear substrate 420 with transparent electrodes 411a and 411b.
And the data electrodes 421 are superimposed on each other so that they face each other and are orthogonal to each other. Then, after evacuating, a mixed gas (discharge gas) such as Ne-Xe is filled in each discharge space at about 500 Torr, for example. By sealing (sealing), the plasma display panel 401 is completed.
Note that the transparent electrodes 411a and 411b and the data electrode 4
The intersection with 21 is one display cell.

The transparent electrode 411a of the front substrate 410
And 411b are alternately scanning electrodes and sustaining electrodes. In the following description, for clarity, the transparent electrodes 411a and 411b are referred to as a scanning electrode 411a and a sustain electrode 411b. Write discharge is performed between the scan electrode 411a and the data electrode 421 of the rear substrate 420 facing the scan electrode 411a.

FIG. 11 shows a driving waveform of the AC three-electrode surface discharge type plasma display panel 401. Note that FIG.
, One display field is divided into subfields SF1 to SF1.
The figure mainly shows the subfield SF1 of the eight divided SF8. The display field and the subfield will be described later in detail.

First, the address discharge will be described with reference to FIG. At the time of write discharge, scan pulse 510 is applied to scan electrode 411a, and data pulse 5 is applied to data electrode 421.
Apply 20. In FIG. 11, the drive waveforms applied to the plurality of scan electrodes 411a are respectively represented by drive waveforms S.
E1 to SE3, and drive waveforms SE1, SE
2 and SE3 correspond to the n-th, n + 1-th, and n + 2-th scan electrodes, respectively. Further, the drive waveform applied to data electrode 421 is set to drive waveform DE, and sustain electrode 411b.
Is a drive waveform ST.

As shown in FIG. 11, a scanning pulse 510 is sequentially applied to all the scanning electrodes, and at the same time, a data electrode 421 is applied.
Is applied so that the data pulse 520 becomes significant or non-significant, and the address discharge is performed on the cells to which the data pulse 520 in the significant state is applied among all the display cells. Note that a period during which the address discharge is performed is referred to as an address period.

After the end of the address period, sustain pulses 511 and 51 are applied to scan electrode 411a and sustain electrode 411b, respectively.
2 is applied, and a sustain discharge is performed between the scan electrode 411a and the sustain electrode 411b. At this time, the sustain discharge occurs only in the display cell in which the data pulse 520 in a significant state is applied in the address period and the wall charge is formed by the address discharge. As described above, by the memory effect of the wall charges, a sustain discharge can be selectively caused in the display cell to display an image. Note that a period during which the sustain discharge is performed is referred to as a sustain period.

The scanning electrode 4 of the plasma display panel
If the number of 11a is large, the time that can be used for the address discharge per line decreases, and the address discharge hardly occurs. Therefore, in order to reliably perform the address discharge in a short time, a scheme has been devised to generate a pilot discharge (priming discharge) prior to the address discharge to enrich the space charge. The period during which pilot discharge is performed is referred to as a pilot period.

In the pilot discharge, a pilot pulse (priming pulse) 513 is applied to all of the scan electrodes 411a and the sustain electrodes 4.
This is a discharge that is generated between the two by applying it to 11b, and it is necessary to set the voltage to a sufficiently high voltage so that the discharge is reliably generated in all the display cells. Therefore, the scanning electrode 41
A high-voltage pulse of a sustain voltage having a different polarity is applied to 1a and the sustain electrode 411b.

In the pilot discharge, not only space charges are generated but also wall charges are generated. When the wall charges generated by the pilot discharge are present, the sustain discharge is generated by the application of the sustain pulses 511 and 512 even in the display cells in which the address discharge has not been performed, and the display cells that should not emit light emit light. Accordingly, the wall charges generated by the pilot discharge are erased by applying the erase pulse 514 to the sustain electrode 411b.
The erase pulse 514 is a pulse having a much shorter duration than the sustain pulses 511 and 512, and the charged particles generated by the erase discharge by the erase pulse 514 recombine at the wall to reduce the wall charge. Note that a period during which the erasing discharge is performed is referred to as an erasing period.

Next, a display method of 256 gradations in the plasma display panel will be described with reference to FIG. FIG. 12 is a diagram schematically showing a general gradation display method, in which the horizontal axis represents time, and the vertical axis represents scan electrode numbers 1 to n.

For example, one display field in a video signal has a time of 1/60 second. By dividing one display field into eight subfields SF1 to SF1
SF8 is defined. Eight subfields SF1 to SF
8 includes a pilot period 611, an erase period 621, a write period 631, and a sustain period 641. And
The length of the sustain period 641 is set so as to become longer sequentially from the subfield SF1 so that the subfield SF8 becomes the longest, and the ratio of the number of sustain pulses given in the sustain period 641 of each of the subfields SF1 to SF8 is 1 : 2: 4: 8: 16: 32: 64: 128.

These eight subfields SF1 to SF
By combining 8, the pulse ratio, that is, 256 levels of 0 to 255 can be expressed by the luminance ratio.

FIG. 13 is a block diagram showing a configuration of a driving device 90 of a general AC three-electrode surface discharge type plasma display panel.

As shown in FIG.
10 is decomposed into subfield data and sent to the data electrode driver 712 for driving data electrodes via the display memory 731. The synchronization signal 720 is input to the driver control unit 723 via the timing control unit 721,
The driver control unit 723 generates various timing control signals to generate the scan electrode driver 724 and the sustain electrode driver 72.
5. Send to the data electrode driver 712. The synchronization signal 720 is also supplied to the memory control unit 732 via the timing control unit 721, and controls the display memory 731. With such a configuration, the drive waveform described with reference to FIG. 11 is given to the scan electrode 411a, the sustain electrode 411b, and the data electrode 421 of the plasma display panel 401, and a predetermined image is displayed.

[0020]

As described above,
When the plasma display panel is driven, eight sub-fields SF1 to SF
A pilot discharge was performed in all of F8. Therefore, even a black display cell (non-discharge cell) emits light due to pilot discharge, which causes a decrease in contrast.

In order to prevent a decrease in contrast, the number of pilot discharges may be reduced. However, conventionally, the number of pilot discharges is simply reduced to one, for example, by performing one pilot discharge in two subfields. A method was used to reduce However, such a simple reduction in the number of pilot discharges has a problem that a write discharge failure occurs at a specific gradation.

That is, since the pilot discharge is a discharge for surely performing the address discharge, the occurrence probability of the address discharge is reduced in a subfield having no pilot discharge. In other words, in a subfield having no pilot discharge, a write discharge failure is likely to occur. When a subfield having no pilot discharge is fixed, the write discharge failure probability of the subfield is always increased in each display field. For example, when a specific gray level is reached, a specific display cell is used. Discharge failure always occurs,
On the screen, display cells that do not light appear to be scattered, resulting in a rough image. This is more remarkable in still images (images fixed as gradations) such as personal computers than in moving images such as videos.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a driving method and a driving apparatus for a plasma display panel which has high contrast and reduces occurrence of write discharge failure in all gradations. The purpose is to do.

[0024]

According to a first aspect of the present invention, there is provided a method of driving a plasma display panel which comprises a plurality of subfields to form one display field and performs gradation display. In the plurality of subfields, the number of subfields having a pilot period in which a pilot discharge for supplying a space charge is performed prior to the address discharge is set to be smaller than the total number of the subfields in the one display field. The seed period is set to be small, and in any of the subfields, the pilot period is set in any of a plurality of continuous display fields.

According to a second aspect of the present invention, in the driving method of the plasma display panel, the number of subfields having the pilot period in one display field is set to be the same in each display field. You.

According to a third aspect of the present invention, in the driving method of the plasma display panel, the number of subfields having the pilot period in one display field is set to one.

In the driving method of a plasma display panel according to a fourth aspect of the present invention, the number of subfields having the pilot period in the one display field is arbitrarily set for each display field.

According to a fifth aspect of the present invention, in the driving method of the plasma display panel according to the fifth aspect of the present invention, the sub-field of the one display field, which has a heavy weight for gradation display corresponding to the length of the discharge sustain period, Always set the pilot period.

According to a sixth aspect of the present invention, in the method for driving a plasma display panel, the plurality of display fields are set so as to include a display field having no subfield having the pilot period. .

According to a seventh aspect of the present invention, there is provided a driving apparatus for a plasma display panel, wherein a plurality of subfields constitute one display field to perform gradation display. A data storage unit for sequentially storing video data to be displayed, and a first storage unit stored in the data storage unit.
Comparing the first video data related to the display field of the second display data with the second video data related to the second display field following the first display field, and detecting a data change for each of the sub-fields, A video signal change detection unit for determining whether or not it is necessary to set a pilot period for performing a pilot discharge for supplying space charges prior to the address discharge for each of the subfields of the second display field.

9. A driving apparatus for a plasma display panel according to claim 8, wherein said first and second video data are each composed of first and second pixel data for each pixel constituting said plasma display panel. The first and second pixel data holding units for temporarily holding the first and second pixel data, respectively, and the first and second pixel data holding units A data comparison unit that compares the first and second pixel data held in the unit for each subfield and outputs a predetermined signal when the two are different, a reference value setting unit that sets a reference value, The number of the predetermined signals output from the data comparison unit is totaled for all of the pixels for each subfield, and based on the magnitude relationship between the total value and the reference value. And a determining data determining section necessity of priming period setting Te.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <A. First Embodiment> As a first embodiment according to the present invention, a driving method of a plasma display panel will be described with reference to FIGS. In addition,
In the following, the display field is divided into four subfields SF1 to SF4 for the sake of simplicity, but it goes without saying that the present invention can be applied to a configuration in which the display field is divided into eight subfields. In the following description, an AC three-electrode surface discharge type plasma display panel will be described.
It goes without saying that the present invention can be applied to any DC type plasma display panel.

The configuration of the AC three-electrode surface discharge type plasma display panel is the same as the configuration 401 of the AC three-electrode surface discharge type plasma display panel described with reference to FIG. In addition, interchange 3
The configuration of the driving device of the electrode surface discharge type plasma display panel is the same as that of the driving device described with reference to FIG.

<A-1. Overall Configuration of Gradation Display Method> FIG.
FIG. 4 is a diagram schematically showing an arrangement pattern of a pilot period according to the first embodiment of the present invention, in which four display fields DF1 are displayed.
DF4 are arranged in the processing order, and in each display field, the horizontal axis indicates time, and the vertical axis indicates scan electrode numbers 1 to n. The display fields DF1 to DF4 are N
The Nth, N + 1, N + 2, and N + 3 display fields are shown.

As shown in FIG. 1, the display field DF1
, The subfield SF1 starts from the pilot period 611 and continues to the erasing period 621, the writing period 631, and the sustaining period 641. However, in the subfields SF2 to SF4, the pilot period is not provided, and the erasing period 621 is not provided.
start from.

<A-2. Detailed configuration of gradation display method> FIG.
Shows details of the driving waveform of the display field FD1. Note that FIG. 2 mainly shows the subfield SF1. The drive waveforms applied to the plurality of scan electrodes 411a are shown as drive waveforms SE1 to SE3, respectively, and the drive waveforms SE1, SE2, and SE3 correspond to the n-th, n + 1-th, and n + 2-th scan electrodes, respectively. The drive waveform applied to data electrode 421 is drive waveform DE, and the drive waveform applied to sustain electrode 411b is drive waveform ST.

As shown in FIG. 2, prior to the application of the scanning pulse 510, a pilot pulse (priming pulse) 513 is applied.
Is applied to all the scan electrodes 411a and the sustain electrodes 411b. Discharge between scan electrode 411a and sustain electrode 411b by application of pilot light pulse 513 (primary discharge)
Occurs, and the space charge becomes rich. In order to ensure that the pilot pulse 513 has a sufficiently high voltage to reliably generate discharge in all display cells, the scan electrode 411a and the sustain electrode 411b are used.
And pulses having different polarities are given. Note that a period during which the pilot discharge is performed is a pilot period 611.

A scanning pulse 510 is applied to the scanning electrode 411a.
When the data pulse 520 is applied to the data electrode 421, a discharge (address discharge) occurs between the two, and a wall charge is formed by the discharge. As shown in FIG. 2, the scan pulse 510 is sequentially applied to all the scan electrodes,
1, the data pulse 520 is applied so as to be significant or non-significant, so that the address discharge is performed on the cells to which the data pulse 520 in the significant state is applied among all the display cells. Note that a period during which the address discharge is performed is an address period 631.

After the end of the address period, sustain pulses 511 and 51 are applied to scan electrode 411a and sustain electrode 411b, respectively.
2 is applied, and a sustain discharge is performed between the scan electrode 411a and the sustain electrode 411b. At this time, the sustain discharge occurs only in the display cell in which the data pulse 520 in a significant state is applied in the address period and the wall charge is formed by the address discharge. As described above, by the memory effect of the wall charges, a sustain discharge can be selectively caused in the display cell to display an image. The period during which the sustain discharge is performed is the sustain period 6
41.

An erasing period 621 for erasing wall charges generated by the pilot discharge is provided between the pilot period and the writing period. In the erase period 621, a discharge (erase discharge) is generated between the sustain electrode 411b and the scan electrode 411a by applying the erase pulse 514 to the sustain electrode 411b. The erase pulse 514 is composed of sustain pulses 511 and 512.
This is a pulse whose duration is much shorter than that of the pulse, and the charged particles generated by the erasing discharge recombine at the wall and the wall charge is reduced.

After the end of the sustain period 641 of the subfield SF1, the end of the subfield SF2 is the erase period 621.
start from. The reason why the erasing period 621 is provided in the subfield having no pilot period as well is to eliminate the discharge maintaining state of the immediately preceding subfield (here, SF1).

In the display field DF2 shown in FIG. 1, the subfield SF2 starts from the pilot period, but the remaining subfields SF1, SF3, SF4
Does not have a pilot period, and the erasing period 621
Starts with.

In the display field DF3, the subfield SF3 starts from the pilot period, but the pilot period is not provided in the remaining subfields SF1, SF2 and SF4.

In the display field DF4, the subfield SF4 starts from the pilot period, but the pilot period is not provided in the remaining subfields SF1 to SF3.

<A-3. Operation and Effect> As described above, in the display fields DF1 to DF4, the pilot period is provided in only one of the subfields, and the subfield in which the pilot period is provided differs for each display field. In the entire display fields DF1 to DF4, it seems that the pilot period is provided in all of the subfields SF1 to SF4. In other words, in any of the subfields, the pilot period is set in any of the continuous display fields. Then, assuming that the display fields DF1 to DF4 are periodically repeated, it appears that the pilot period moves in the subfields SF1 to SF4.

As described above, the display field is updated every 1/60 second in a video signal, for example, so that the display field is updated 60 times per second. Therefore, if the display fields DF1 to DF4 are one unit,
When the process starts from the display field DF1 and ends at DF4 (one cycle), the display field DF1 starts again.
This cycle is repeated 15 times per second.

Next, the effect of moving the subfields SF1 to SF4 apparently during the pilot period will be described.

As described above, the pilot discharge is for ensuring that each display cell performs the address discharge in a short time, and has an effect of enriching the space charge.
Accordingly, when gradation display is performed in a subfield having no pilot discharge, the probability that a display cell (defective cell) having a defective write discharge among all the display cells appears. Therefore, if the pilot discharge is always set to only the subfield SF1 in all display fields, that is, if it is fixed, when performing gradation display using the subfields SF2 to SF4, the defective cell Is likely to appear. The cause of the defective cell may be the quality of the state of the immediately preceding subfield (whether or not the cell is discharged). However, it is also conceivable that the cell has a structure that is difficult to discharge.

That is, a defect that occurs during the manufacturing process of a display cell may cause a structure that is more difficult to discharge than other display cells. A pilot discharge is necessary to surely perform the address discharge in such a display cell. However, if the pilot discharge is fixed, gradation display is performed only in a subfield having no pilot discharge. In this case, a display cell having a discharge failure always appears. When this is viewed on a screen, display cells that do not light (discharge) at a specific gray level appear to be scattered, resulting in a rough image.

However, the subfield in which the pilot period is set is changed for each display field, and the pilot period is provided in all subfields in the entire display field. It is possible to prevent the appearance of a display cell.

Taking the gradation display method shown in FIG. 1 as an example, for example, in a gradation screen displayed in the subfield SF2, the display field DF1 has the subfield S.
Since F2 does not have the pilot period 611, even if a certain display cell (referred to as a display cell X) does not light due to a write failure, the display field DF2 does not have the subfield SF.
Since 2 has the pilot period 611, the display cell X is turned on.

In the display fields DF3 and DF4, there is a possibility that the display cell X does not light up. However, when the display field DF2 is reached again, the display cell X turns on. Therefore, the display cell X is simply cycled 15 times per second. Will be lit. If it is turned on 15 times a second, even if it is periodically, it looks as if it is turned on continuously to human eyes. Therefore, the image having a rough feeling is eliminated, and since the pilot period is reduced, the possibility that light emission due to pilot discharge is generated in the black display cell (non-discharge cell) is reduced, the contrast is improved, and a high quality image is obtained. Is obtained.

When the subfields are used in combination, the number of lightings per second is further increased. That is, taking the display field DF1 as an example, when the subfields SF1 and SF2 are combined, the display cell X is turned on because the subfield SF1 has the pilot period 611. Since the display cell X maintains the state of having the space charge generated by the sustain discharge in the subfield SF1, the sustain discharge (lighting) is performed without causing the address discharge failure in the display cell X in the subfield SF2. And the number of lightings per second increases. This means that the sustain discharge in the subfield SF1 replaces the pilot discharge for the subfield SF2.

As described above, in gradation display by a combination of a plurality of subfields, if at least one of the subfields has a pilot period, writing discharge failure is prevented in the subsequent subfield, and lighting is performed. The appearance of defective (sustain discharge defective) display cells can be prevented.

In order to realize the drive pattern as shown in FIG. 1, the arrangement pattern of the pilot period may be input to the driver control unit 723 in advance. The arrangement pattern of the pilot period may be a regular pattern as shown in FIG. 1 or an irregular pattern. Hereinafter, a modification of the arrangement pattern of the pilot period will be described.

<A-4. Modification 1> In the first embodiment described above, in the display fields DF1 to DF4, a sub-field in which only one of the sub-fields is provided with a pilot period and a pilot period is provided for each display field. Although the example in which they are made different has been described, the pattern of the arrangement of the pilot period is not limited to this.

For example, a pilot period may be provided in a plurality of subfields, and the subfields (arrangement patterns of the pilot period) in which the pilot period is provided may be different between display fields before and after. An example of this is shown in FIG.

In FIG. 3, in display field DF1, subfields SF1 and SF3 have a pilot period, but the remaining subfields SF2 and SF3 are different.
4 does not have a pilot period. In display field DF2, subfields SF2 and SF
4 has a pilot period, but the remaining subfield S
No pilot period is provided for F1 and SF3. In the display field DF3, the subfield S
F1 and subfield 3 have a pilot period, but the remaining subfields SF2 and SF4 do not have a pilot period.

As described above, among the subfields constituting the display field, a plurality of display fields are provided with a pilot period, and the subfields provided with the pilot period are different in the preceding and succeeding display fields. By setting the pilot period in all the subfields as a whole, it is possible to prevent the appearance of display cells that always have a discharge failure.

Also, since a pilot period is provided in a plurality of subfields in the display field, the period until the pilot period is provided in all the subfields (referred to as a defective display cell lighting period) is apparently shown in FIG. Is shorter than the pattern shown in FIG. That is, in the example shown in FIG. 3, only the display fields DF1 and DF2 are apparently provided with a pilot period in all subfields, and the display field DF3 is a repetition of DF1.

In FIG. 3, one display field is composed of four subfields. However, since it is usually composed of eight subfields, a subfield having a pilot period in one display field is included. In one case, the defective display cell lighting cycle is lengthened, and the number of times of lighting of the defective display cell is reduced. However, the defective display cell lighting cycle can be reduced by using a plurality of subfields having a pilot period in one display field. The length can be shortened, and a high-quality image can be obtained.

It is to be noted that the number of subfields having a pilot period in one display field is preferably more than a single field, but the larger the number is, the closer to the prior art, the lower the contrast. It is necessary to pay attention to the setting of the number. When setting the number of subfields having a pilot period, an index may be used to determine whether the lighting cycle of the defective display cell is within a range that can be sensed by human eyes.

For example, if one display field is composed of eight subfields, as shown in FIG.
If the pilot period is set in two subfields in the display field, the still image is turned on 15 times per second for a still image. The film speed of a movie is 24 frames per second, and blinking 15 times per second cannot be clearly confirmed by human eyes.

<A-5. Modification 2> In the first and modification 1 according to the present invention described above, the number of subfields having a pilot period in one display field is the same in any of the display fields. However, this number may be set arbitrarily for each display field. An example of this is shown in FIG.

In FIG. 4, in the display field DF1, the subfield SF4 has a pilot period, but the remaining subfields SF1 to SF3 have no pilot period. In the display field DF2, the subfields SF3 and SF4 have a pilot period, but the remaining subfields SF1 and SF4
2 does not have a pilot period. In the display field DF3, the subfields SF2 to SF4 have a pilot period, but the subfield SF1 has no pilot period. The display field DF
In subfield 4, subfields SF1 and SF4 have a pilot period, but the remaining subfields SF2 and SF3 have no pilot period.

As described above, the number of subfields having a pilot period in one display field is arbitrarily set for each display field, and the pilot period is set in all subfields in a plurality of display fields. By providing the display cells, it is possible to prevent the appearance of display cells that cause a discharge failure. In addition, the degree of freedom of the arrangement pattern of the pilot period increases.

In the example shown in FIG. 4, the subfield SF4 has a pilot period in any of the display fields. This is because the sustain period 641 of the subfield SF4 is the longest and the weight for gradation display is small. Is a heavy subfield, so that the appearance of defective display cells in the subfield is minimized.

That is, even if a defective display cell appears in the subfield SF1, the presence of the defective display cell is inconspicuous because the luminance in the subfield SF1 is low.
When a defective display cell appears in the subfield SF4, the presence of the defective display cell becomes conspicuous because the surroundings are high-luminance images. In this way, by setting a pilot period as much as possible in a subfield having a heavy weight for gradation display, the appearance of conspicuous defective display cells can be reduced.

<A-6. Modification 3> In the first embodiment, modifications 1 and 2 according to the present invention described above, a pilot period is provided in at least one subfield in any of the display fields, but a pilot period is provided. A configuration may exist in which there is a display field that does not have the specified subfield. An example of this is shown in FIG.

In FIG. 5, in the display field DF1, the subfield SF1 has a pilot period, but the remaining subfields SF2 to SF4 are not provided with a pilot period. In the display field DF2, the subfield SF2 has a pilot period, but the remaining subfields SF1, SF3, and SF4 are not provided with a pilot period. The display fields DF3 and DF4 do not have a subfield in which a pilot period is provided. In the display field DF5, the subfield SF3 has a pilot period, but the remaining subfields SF1, SF2, and SF4 have no pilot period. Display field D
In F6, the subfield SF4 has a pilot period, but the pilot periods are not provided in the remaining subfields SF1 to SF3.

As described above, even if there is a display field having no subfield provided with a pilot period (referred to as a display field having no pilot period) among a plurality of display fields, a plurality of display fields are provided. By setting a pilot period in all subfields in the entire display field, it is possible to prevent the appearance of display cells that always have a discharge failure. Further, when displaying an image with little change, the contrast can be improved. For example, it is suitable for a case where an image having many black display cells and little change is frequently used.

It should be noted that even if there is a display field having no pilot period, there is no significant problem in gradation display. That is, as described above, since the sustain discharge functions as a substitute for the pilot discharge, even if the pilot discharge is not performed at all for a certain period of time, the appearance of defective display cells does not always occur frequently during that period. Because.

For example, based on the pilot discharge of subfield SF2 of display field DF2, subfield S
If the address discharge is reliably generated in F3 and SF4 and the sustain electrode is performed, the probability that the address discharge is generated in the subfields SF1 to SF4 of the display field DF3 is high. Thus, the reason why the sustain discharge in the immediately preceding subfield can be used as a pilot discharge is that the space charge generated by the discharge does not disappear immediately.
It has been confirmed by the inventor that, even when about two display fields having no pilot period continue, the probability of occurrence of address discharge does not decrease so much in an image with little change.

<B. Second Embodiment> In the first embodiment described with reference to FIGS. 1 to 5, the pilot period is arranged based on a predetermined pattern. May be changed according to the conditions. For that purpose, it is necessary to make the configuration of the driving device of the plasma display panel different from that of the conventional device.

Hereinafter, a second embodiment according to the present invention will be described.
The configuration and operation of the driving device of the plasma display panel for changing the arrangement pattern of the pilot period according to the video data will be described with reference to FIGS.

<B-1. Necessity of Changing Arrangement Pattern of Pilot Period> First, the necessity of changing the arrangement pattern of the pilot period according to video data will be described with reference to FIG.
FIG. 6 is a diagram schematically showing a case in which data of each subfield of two display fields in a context is displayed as an image. In FIG. 6, the display field DFX is the previous field, the display field DFX is the current field,
Each has subfields SF1 to SF8.

As shown in FIG. 6, the images P1 and P2 based on substantially the same data are displayed in the respective subfields SF1 of the display fields DFX and DFX, but the subfields SF2 of the display field DFX are displayed.
Displays a new image P3.

Note that the gradation of the image P1 is the same as the subfield S
The image P1 is not displayed after the subfield SF2 of the display field DFX.
However, since the space charge is held by the sustain discharge in the display cell displaying the image P1, the display field DF is displayed.
In the Y subfield SF1, when displaying the image P2, there is a high probability that address discharge and sustain discharge will occur even if there is no pilot discharge. However, a pilot discharge is required to reliably display the new image P3 in the subfield SF2 of the display field DFY.

In the driving method described in the first embodiment according to the present invention, the arrangement pattern of the pilot period is determined in advance.
It is highly possible that the pilot period is not provided in the Y subfield SF2.

Therefore, in the display fields in the context, the data change in the entire screen of each subfield is checked, and it is determined whether or not it is necessary to set a pilot period for each subfield of the subsequent display field. It is possible to change the arrangement pattern of the fire period according to the video data, and reduce the appearance of defective display cells and reduce the appearance of roughness even when images are different in the preceding and following display fields such as moving images. The image is eliminated, and the possibility that light emission due to pilot discharge occurs in the black display cell (non-discharge cell) is reduced, the contrast is improved, and a high-quality image is obtained.

<B-2. Configuration and Operation of Entire Apparatus> Next, the configuration of a driving apparatus 100 for a plasma display panel having means for determining whether or not to set a pilot period for each subfield will be described with reference to FIG.

Driving device 1 for plasma display panel
00 indicates that the digital video signal 710 (second video data) is transmitted via the display memory 711 (data storage unit) to the data electrode driver 712 for driving the data electrode 421.
And is sent after being decomposed into subfield data. The synchronization signal 720 is input to the driver control unit 723 via the timing control unit 721, and the driver control unit 723 generates various timing control signals to generate the scan electrode driver 7
24, sustain electrode driver 725, data electrode driver 7
Send to 12. This basic configuration is the same as the conventional device,
A gradation-specific video signal change detection unit 713 is newly provided, a digital video signal 710 is externally supplied, and a digital video signal 730 (first
Is provided to the gradation-specific video signal change detection unit 713.

The gradation-based video signal change detection unit 713 compares the video signals between the display fields in the preceding and following relations, checks the data change in each subfield, and sets the pilot period for each subfield. It has a function to determine whether or not it is not. Then, a determination result signal 740 indicating the determination result of the necessity of setting the pilot period is provided to the driver control unit 723, and the driver control unit 723 sets the pilot field in the subfield to be determined based on the determination result. The scan electrode driver 724, the sustain electrode driver 725, and the data electrode driver 712 are controlled so as to set a period or start from an erasing period without providing a pilot period. It should be noted that the synchronization signal 720 is provided to the gradation-specific video signal change detection unit 713 via the timing control unit 721. The synchronization signal 720 is also provided to the memory control unit 722 via the timing control unit 721,
The display memory 711 is controlled.

In the driving apparatus 100 for a plasma display panel having such a configuration, the arrangement pattern of the pilot period of the gray scale display method changes according to the applied video signal 710 and cannot be presented as a drawing. As described in the first embodiment, it is not necessary to set a pilot period in all subfields in a plurality of display fields.

<B-3. Configuration of Video Signal Change Detection Unit for Each Tone> Next, a specific configuration of the video signal change detection unit for each gradation 713 will be described with reference to FIGS. FIG. 8 is a block diagram illustrating the configuration of the gradation-specific video signal change detection unit 713.

The gradation-based video signal change detection unit 713 includes pixel data holding units 10 and 20 for temporarily holding pixel data of display fields in a sequential relationship, and pixel data holding units 10 and 20 (first and second). A data comparison unit 30 that compares the pixel data held in the second pixel data holding unit), compares the data comparison result with a preset reference value, and determines a magnitude relationship between the data comparison result and the reference value. And a reference value setting unit 50 for setting a reference value.

The video signal 710 of the display field to be determined is input to the pixel data holding unit 10 as current pixel data (second pixel data). The video signal 730 of the previous (ie, 1/60 second before) display field is input as the immediately preceding pixel data (first pixel data). In addition,
The pixel data holding units 10 and 20 are provided with a synchronization signal from the timing control unit 721 in order to synchronize with the operation of the display memory. Further, the data determination unit 40 outputs a determination result signal 74 indicating the determination result of the magnitude relationship between the data comparison result and the reference value (that is, the determination result of necessity of setting the pilot period).
0 is output.

Next, a more specific configuration example of the gradation-based video signal change detection section 713 will be described with reference to FIG. FIG.
As shown in the figure, the pixel data 710 and 730 input to the gradation-specific video signal change detection unit 713 are 8-bit data, and the pixel data holding units 10 and 20 are configured by 8-bit memories M1 and M2. I have.

The respective bit information of the memories M1 and M2 are paired with the same bit, and are each a pair of exclusive OR gates (EXOR gates) EX1 to EX.
It is configured to be input to X8. That is, the data comparison unit 30 is constituted by EXOR gates EX1 to EX8.

The outputs of the EXOR gates EX1 to EX8 are input to the counters K1 to K8,
The count value at K8 is calculated by comparators C1 to C8, respectively.
It is configured to compare with a preset reference value. The reference value is set in the reference value setting section 50 by the comparator C.
It is configured such that it can be determined corresponding to each of 1 to C8. In the comparators C1 to C8, if the reference value is A and the count values of the counters K1 to K8 are B, A
If> B, it is determined that there is little change in gradation and it is determined that it is not necessary to set the pilot period. Note that the determination result is a sub-field SF1 to SF as a determination result signal 740.
8 is output.

<B-4. Operation of Video Signal Change Detector by Gradation> Next, the operation will be described with reference to FIG. 8-bit data provided as pixel data 710 and 730 corresponds to subfields SF1 to SF8. That is, the pixel data 710 is given, for example, 001111010 (3AH in hexadecimal notation) as the current pixel data, and the LSB (least significant bit) is set in the subfield SF1.
, And the MSB (most significant bit) indicates the gradation bit of the subfield SF8. Similarly, the pixel data 730 is, for example, 00111000 as the previous pixel data.
(38H in hexadecimal notation), the LSB indicates the gradation bit of the subfield SF1, and the MSB indicates the gradation bit of the subfield SF8.

Here, the “current pixel data” is
The data of one pixel unit being input to the input terminal In of the display memory 711 is referred to as “previous pixel data”.
The data output from the output terminal Out2 of the display memory 711 and indicating the data being displayed on the plasma display panel 401 in pixel units. The data is output from the output terminal Out1 in accordance with the input timing of the pixel data 710.

A comparison between the pixel data 710 and 730 reveals that only the bit immediately before the LSB has changed. This means that a new image has appeared in the subfield SF2.

If this example is applied to FIG. 6, a new image P3 on the subfield SF2 of the display field DFY is shown. Note that pixel data 710 and 730 are 1
Since the data is pixel-by-pixel, it is necessary to perform a similar comparison on a plurality of pixel data in order to recognize whether or not the image has changed.

EX is compared with pixel data 710 and 730.
This is performed in the OR gates EX1 to EX8. In this example, only the output of the EXOR gate EX1 becomes 1, and the count of only the counter K1 is incremented by 1 bit. That is, the counter K1 counts the number of pixels whose data has changed between the respective subfields SF1 of the preceding and succeeding display fields. This is the same for the counters K2 to K8.

Such pixel data 710 and 730
Is performed during one display field period (1/60 second) for all pixels, the value counted by the counters K1 to K8, that is, there is a data change between the subfields of the preceding and succeeding display fields. The number of pixels is compared with a preset reference value in the comparators C1 to C8.
Then, in the subfield whose count value is lower than the reference value, it is determined that there is no need to provide a pilot period since the data change between the preceding and following display fields is small, that is, the change in the image is small. The fact is transmitted to the driver control unit 723.

As described above, since the pixel data to be determined is data of a display field next to the data being displayed on the plasma display panel 401, the determination result is that the pixel data to be determined is a plasma field. When displayed on the display panel 401, the scan electrode driver 724, the sustain electrode driver 725, and the data electrode driver 712 set a pilot period in which subfield and do not set a pilot period in which subfield. Thus, the arrangement pattern of the pilot period according to the video data can be changed.

[0098]

According to the method of driving a plasma display panel according to the first aspect of the present invention, the number of subfields having a pilot period among a plurality of subfields is reduced by a plurality of subfields in one display field. It is set smaller than the total number of subfields, and in each of the subfields, a pilot period is set in any of a plurality of continuous display fields. Even when there are display cells that are difficult to display, it is possible to prevent the appearance of display cells that always have a discharge failure, and to eliminate the rough image caused by the presence of the display cells that have a discharge failure. In addition, since the number of subfields having the pilot period is reduced, the possibility of light emission due to pilot discharge in the black display cells (non-discharge cells) is reduced, the contrast is improved, and a high-quality image is obtained.

According to the driving method of the plasma display panel according to the second aspect of the present invention, the arrangement pattern of the pilot period is simplified, and the control for realizing the arrangement pattern becomes easy.

According to the driving method of the plasma display panel according to the third aspect of the present invention, the arrangement pattern of the pilot period is further simplified, and the possibility that light emission due to the pilot discharge occurs in the black display cell is minimized. And the contrast is most improved.

According to the driving method of the plasma display panel according to the fourth aspect of the present invention, the degree of freedom of the arrangement pattern in the pilot period is increased.

According to the method of driving a plasma display panel according to the fifth aspect of the present invention, the appearance of defective display cells in a subfield having a heavy weight for gradation display can be prevented as much as possible, and the appearance of conspicuous defective display cells is reduced. can do.

According to the driving method of the plasma display panel according to the sixth aspect of the present invention, by providing a display field having no subfield having a pilot period, the number of black display cells is increased and the number of black display cells is changed. It is possible to improve the contrast when displaying an image with few images.

According to the plasma display panel driving apparatus of the seventh aspect of the present invention, in the first and second display fields which are in a sequential relationship, the data change of each sub-field is checked, and the first and second display fields are checked in the subsequent stage. By determining the necessity of setting the pilot period for each subfield of the display field of No. 2, it is possible to change the arrangement pattern of the pilot period according to the video data. In the case where the image is different, the appearance of the defective display cell is reduced to eliminate the rough image, and there is a possibility that the light emission due to the pilot discharge occurs in the black display cell (no discharge cell). As a result, the contrast is improved, and a high-quality image can be obtained.

According to the plasma display panel driving apparatus of the eighth aspect of the present invention, the simplest and practical configuration for checking the data change of the first and second display fields in the context is as follows. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an arrangement pattern of a pilot period according to a first embodiment of the present invention.

FIG. 2 is a partial detailed diagram illustrating a drive waveform of a display field according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a modification of the arrangement pattern of the pilot period according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a modification of the arrangement pattern of the pilot period according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a modification of the arrangement pattern of the pilot period according to the first embodiment of the present invention.

FIG. 6 is a diagram schematically showing a case where data of each subfield of two display fields in a context is displayed as an image.

FIG. 7 is a diagram illustrating a configuration of a driving device of a plasma display panel according to a second embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of a video signal change detection unit for each gradation.

FIG. 9 is a diagram illustrating a more specific configuration example of a gradation-specific video signal change detection unit.

FIG. 10 is a perspective view showing a cross-sectional configuration of an AC three-electrode surface discharge type plasma display panel.

FIG. 11 is a diagram showing a conventional driving waveform of an AC three-electrode surface discharge type plasma display panel.

FIG. 12 is a diagram schematically showing a general gradation display method.

FIG. 13 is a block diagram showing a configuration of a driving device of a general AC three-electrode surface discharge type plasma display panel.

[Explanation of symbols]

401 plasma display panel, 611 pilot period, 631 writing period, 641 sustaining period, SF1
SF4 subfield, DF1 to DF6 display field.

Claims (8)

[Claims] 1. A method of driving a plasma display panel for performing gray scale display by forming one display field by a plurality of subfields, comprising: a pilot discharge for supplying a space charge prior to an address discharge among the plurality of subfields. The number of subfields having a pilot period for performing the above is set to be smaller than the total number of the plurality of subfields in the one display field, and any of the subfields is set in any of a plurality of continuous display fields. A method for driving a plasma display panel in which the pilot period is set. 2. The method according to claim 1, wherein the number of subfields having the pilot period in one display field is set to be the same in each display field. 3. The driving method of a plasma display panel according to claim 2, wherein the number of subfields having the pilot period in one display field is set to one. 4. The method according to claim 1, wherein the number of subfields having the pilot period in one display field is arbitrarily set for each display field. 5. The pilot period is always set in a sub-field of the one display field, the sub-field having a heavy weight for gradation display corresponding to the length of the discharge sustaining period. A method for driving a plasma display panel. 6. The driving method for a plasma display panel according to claim 1, wherein the plurality of display fields are set to include a display field having no subfield having the pilot period. 7. A driving apparatus for a plasma display panel that performs a gray scale display by forming one display field by a plurality of subfields, a data storage unit that sequentially stores video data displayed on the plasma display panel, Comparing the first video data related to the first display field stored in the data storage unit with the second video data related to a second display field following the first display field, and Signal change for each subfield of the second display field to determine whether it is necessary to set a pilot period for performing a pilot discharge for supplying a space charge prior to the address discharge. A driving device for a plasma display panel, comprising: 8. The first and second video data are provided as first and second pixel data, respectively, for each pixel constituting the plasma display panel, and the video signal change detection unit includes: First and second pixel data holding units for temporarily holding the first and second pixel data, respectively, and the first and second pixel data held in the first and second pixel data holding units. A data comparison unit that compares each subfield and outputs a predetermined signal when the two are different, a reference value setting unit that sets a reference value, and a number of the predetermined signal output from the data comparison unit. Aggregate over all of the pixels for each subfield,
The plasma display panel driving device according to claim 7, further comprising: a data determination unit that determines whether or not it is necessary to set a pilot period based on a magnitude relationship between the total value and the reference value.