JP2003015596A - Drive method for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive method of a plasma display panel, capable of preventing lighting failure and moreover capable of shortening a scan period, by making discharge probability raised and shortening the discharge delay time of write discharge. SOLUTION: In this driving method of a plasma display panel, the selecting of a sub-field with respect to display gradation is changed by the selected state of the sub-field of an adjacent cell and a sub-field identical to that of the adjacent cell or a sub-field of one sub-field before is selected. As a result, the same sub-field is made to be selected in adjacent cells with each other, in which discharge space is connected; and since the discharge probability of the adjacent cell is raised by charged particles and a meatastable state which are diffused from a cell, in which write discharge is first generated, the discharge delay time of the write discharge can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a plasma display panel, and more particularly to a method for driving a plasma display panel for performing an AC discharge type matrix display.

[0002]

2. Description of the Related Art Plasma display panels are classified into a DC type in which an electrode is exposed to a discharge gas and an AC type in which an electrode is covered with a dielectric and is not directly exposed to a discharge gas according to a structural classification. is there. Further, the AC type includes a memory operation type that uses a memory function by the charge storage function of the dielectric and a refresh operation type that does not use the memory function.

The structure and driving method of a general memory operation type AC plasma display panel will be described with reference to the accompanying drawings. FIG. 10 is a cross-sectional view of a main part showing this conventional plasma display panel.

In the plasma display panel,
Two insulating substrates 1a and 1b on the front surface and the back surface are provided so as to face each other. On the insulating substrate 1a, the scan electrodes 2 and the sustain electrodes 3 are arranged in parallel with each other at a predetermined interval. The sustain electrode 3 is also called a common electrode. The scan electrodes 2 and the sustain electrodes 3 are covered with a dielectric layer 4a, and a protective film 5 made of magnesium oxide or the like for protecting the dielectric layer 4a from discharge is formed on the dielectric layer 4a.

Data electrodes 6 are arranged on the insulating substrate 1b so as to be orthogonal to the scan electrodes 2 and the sustain electrodes 3. The data electrode 6 is covered with the dielectric layer 4b,
On b, a partition wall 7 is formed for securing a discharge space and partitioning cells. Data electrode 6 between partition walls 7
Are arranged and extend parallel to each other. On the dielectric layer 4b where the partition 7 is not formed and on the side surface of the partition 7, a phosphor 8 for converting ultraviolet rays generated by discharge into visible light is applied. Color display can be performed by separately applying the phosphor 8 to each cell, for example, red, green, and blue (RGB), which are the three primary colors of light.

The insulating substrate 1a and the insulating substrate 1b are separated by a partition wall 7
Are brought into contact with the protective film 5 to be stacked and assembled. Then, a discharge gas composed of helium, neon, xenon, or the like or a mixed gas thereof is sealed in the space sandwiched between the insulating substrates 1a and 1b and partitioned by the partition wall 7.

FIG. 11 is a plan view of the plasma display shown in FIG. 10 viewed from the display surface side. The scan electrodes 2 and the sustain electrodes 3 are arranged alternately in pairs in parallel with the row direction. Of the distances between the scan electrodes 2 and the sustain electrodes 3, the smaller distance is called a discharge gap, and a surface discharge is generated between the scan electrodes 2 and the sustain electrodes 3 at the position of the discharge gap. On the other hand, the larger distance is called a non-discharge gap, and the size of this non-discharge gap is set to a value such that discharge does not occur accidentally between adjacent cells.

Next, a driving method of a conventional memory operation type AC plasma display panel will be described with reference to FIG. FIG. 12 is a time chart showing voltage pulses applied to each electrode in the conventional driving method. As shown in FIG. 12, one basic driving cycle includes a preliminary discharge period, which is a period for initializing the state of cells to facilitate discharge, a scanning period, which is a period for selecting cells to be displayed, It is separated into a sustain period which is a period in which a cell selected in the scanning period emits light.

First, in the preliminary discharge period, an erase pulse is applied to all the scan electrodes 2 (Nos. 1 to N) to stop the discharge of the display cells that have been emitting the sustain discharge before the time shown in the figure, and all of them are stopped. The display cell of is set to the erased state. Next, a preliminary discharge pulse is applied to all the scan electrodes 2 (No. 1 to N) and the sustain electrodes 3 to force all the display cells to discharge and emit light, and further, all the scan electrodes 2 (No. 1 to N). ) Is applied to erase the discharge of all the display cells. These pre-discharge and pre-discharge erasing facilitate the subsequent address discharge.

In the scanning period, the scanning pulse is sequentially applied to each scanning electrode 2 while shifting the timing, and the data pulse is applied to the data electrode 6 in accordance with the display data at the timing when the scanning pulse is applied. In the cell to which the data pulse is applied when the scan pulse is applied, discharge is generated between the scan electrode 2 and the data electrode 6. This is called address discharge. When the address discharge is generated, positive charges are accumulated in the dielectric layer 4a on the scan electrode 2 and negative charges are accumulated in the dielectric layer 4b on the data electrode 5.

In the sustain period, the sustain electrode 3 and the scan electrode 2
A sustain pulse is applied between (No. 1 to N).
Then, when the address discharge is generated in the scanning period and the voltage due to the charges stored in the dielectric layer 4a is superimposed on the voltage of the sustain pulse, the surface discharge is generated between the scan electrode 2 and the sustain electrode 3. To do. The voltage of the sustain pulse is set to a voltage that does not exceed the starting voltage at which surface discharge occurs when the address discharge is not generated in the scanning period and the wall charge is not formed in the dielectric layer 4a. . Therefore, the sustain discharge for display is generated only in the selected cell in the scanning period.

When the first sustain discharge is generated, negative charges are accumulated in the dielectric layer 4a on the scan electrodes 2 and positive charges are accumulated in the dielectric layer 4a on the sustain electrodes 3. The second sustain pulse is different from the first sustain pulse in scan electrode 2
Since the polarity of the voltage applied to the common electrode 3 is reversed, the voltage due to the charges accumulated in the dielectric layer 4a is superimposed, and the second discharge is generated. After that, the sustain discharge is similarly continued.

When the surface discharge is not generated in the first sustain pulse, the discharge is not generated in the subsequent sustain pulses.

As explained above, the preliminary discharge period,
The three periods of the scan period and the sustain period are collectively called a subfield.

Next, a gradation expression method of the plasma display panel will be described with reference to FIG. One field, which is a period for displaying one screen, is divided into a plurality of subfields. The driving method in each subfield is as shown in FIG. 12, and the display can be turned on / off independently for each subfield. In addition, the number of sustain pulses is different for each subfield.

[0016] Generally, one field is divided into n sub-fields, setting the luminance ratio of each subfield into 2 ^n, 2 ⁿ gradation display becomes possible. For example, in order to display 256 gradations, since 2 ⁸ = 256, eight subfields weighted by binary are required.

However, in actual driving, since a false contour of a moving image, which is peculiar to the subfield method, is generated, a method with redundancy is often adopted, unlike the binary method. In that case, Is divided into 9 subfields or more. When one field is divided into 12 subfields, the weighting of each subfield is as shown in FIG. 14, for example.

In the case of 2 ⁿ gradation display by ⁿ subfields, there is only one combination of subfields expressing one gradation, but if the subfields are divided with redundancy. For a certain gray scale, there are a plurality of combinations of subfields expressing the gray scale. Therefore, the brightness gradation and the selective coding of the subfields are set to be uniquely determined by a look-up table (LUT) or the like. In that case, in order to suppress the deterioration of the false contour of the moving image, the lower-order bits, which are usually less weighted, are preferentially selected.

FIG. 15 is a schematic diagram showing the operation of subfield selection. Subfield coding circuit 100
Receives the input grayscale signal and converts it to grayscale, and then LUT10
1 is read to determine the subfield to be selected, and a subfield selection signal is output to the drive circuit 102.

Next, the driving stability during the scanning period will be described. In the scanning period, some time is required from the application of the scanning pulse to the generation of the address discharge. This time is called the discharge delay time. This discharge delay time is determined as a stochastic value by various parameters of the plasma display panel, and as an important index among them, the density of charged particles and metastable (atoms of metastable levels) in the discharge space, etc. Is mentioned. Sources of these particles include preliminary discharge and sustain discharge. The presence of these particles increases the ease with which discharge occurs, that is, the discharge probability. When the discharge probability increases, the discharge delay time is shortened.

However, the number of charged particles and metastable decreases with time, and the discharge probability also decreases with time. Therefore, in order to utilize these particles, it is preferable that as little time as possible has elapsed after the particles were generated.

The charged particles and metastable generated in the preliminary discharge have a low initial density, and those generated in the sustain discharge have a small amount when the number of discharges is small.
A large effect on the particle density at the time of address discharge cannot be obtained.

Therefore, in the conventional plasma display panel driving method, when the width of the scanning pulse is shortened in the scanning period, the writing discharge may not be generated within this pulse width, and lighting failure may occur. It was This is particularly noticeable when a subfield having a small number of sustain pulses is independently selected.

Therefore, in the invention disclosed in Japanese Patent Laid-Open No. 2000-155556, discharge is generated in all cells of the plasma display panel regardless of selection / non-selection as means for surely generating address discharge. Therefore, attempts have been made to speed up the address discharge.
When line-sequential scanning is performed, discharge is caused in all cells included in the selected row to generate charged particles and metastable. The discharge delay time is shortened by diffusing them into adjacent rows in the lower order of the scanning order and scanning the row immediately after.

In addition, there is a technique in which an auxiliary discharge cell different from the display cell is provided and a discharge is generated in the auxiliary discharge cell immediately before the address discharge in the display cell, thereby speeding up the address discharge in the display cell. It is disclosed in Japanese Patent Laid-Open No. 5-250995. This is to increase the discharge probability of the discharge space by generating charged particles and metastable in the auxiliary discharge cell, thereby shortening the discharge delay time.

Further, the preliminary discharge erasing pulse is always arranged immediately before the scanning pulse, and the discharge is always generated immediately before the scanning pulse enters, whereby charged particles and metastable are generated, and the discharge delay time is shortened. Japanese Patent Laid-Open No. 10-1
It is disclosed in Japanese Patent No. 49133.

[0027]

However, as described above, in order to surely generate the address discharge even if the discharge probability is low, the scan pulse width may be set sufficiently larger than the discharge delay time. As the scanning pulse width is increased, the scanning period is increased and the time that can be used in the sustain period is shortened. As a result, there is a problem that the emission brightness is reduced.

In the method described in Japanese Patent Laid-Open No. 2000-155556, discharge is generated in all cells regardless of display data during the scanning period, so that light emission unrelated to the image is generated on the entire panel, There is a problem that the black brightness increases and the contrast decreases. Also,
Since discharge is generated on the entire surface, wall charges are formed in all cells. Therefore, as compared with the conventional driving method in which the writing discharge is generated only in the selected cell and the display is turned on / off depending on the presence or absence of the wall charge, the cell selectivity is deteriorated.

In the method described in Japanese Patent Laid-Open No. 5-250995, the installation of the auxiliary discharge cells complicates the panel structure and deteriorates the yield during panel manufacturing. Further, the area of cells applicable to display is reduced and the effective aperture ratio is reduced, which is unsuitable for high definition.

In the method described in Japanese Patent Laid-Open No. 10-149133, it is necessary to scan the preliminary discharge erasing pulse in addition to the scanning pulse, which causes a problem that the driving circuit becomes complicated and the circuit cost increases.

The present invention has been made in view of the above problems, does not require any change or addition of the panel structure and the driving driver, does not increase the black luminance, and speeds up the address discharge. As a result, it is an object of the present invention to provide a driving method of a plasma display panel, which can prevent defective lighting and can shorten the scanning period.

[0032]

A driving method of a plasma display panel according to the present invention divides one field into a plurality of subfields having at least a plurality of types of luminance weighting, and makes a display selection of each subfield individually. A method of driving a plasma display panel that performs gradation expression by performing the method, characterized in that selection of a subfield for display gradation is changed depending on a selected state of a subfield of an adjacent cell.

In the present invention, the subfields are selected so that the same subfield as the subfield selected in the next row in the same column is preferentially selected according to the order of discharging for selection. The selection state can be changed.

Also, depending on the order of discharging for selection, the selection state of the subfields is changed so that the same subfield as the subfield selected two rows later in the same column is preferentially selected. be able to.

Further, the discharge can be performed in a line-sequential and continuous manner for the display rows.

Furthermore, the order of discharging for selection may be every other display row. The same subfield as the subfield selected by the adjacent cell in the same display row may be preferentially selected.

It is possible to change the selection state so that the same subfield is selected only for the subfields with low weighting. Further, the selection state of the subfield can be changed so that the subfield before the subfield selected by the adjacent cell is preferentially selected.

At this time, when the subfields selected in the adjacent cells are the subfields with low weighting,
The selection state of the subfield can be changed.

Further, the display gradation can be changed so that the same subfield as the subfield selected in the next row in the same column is selected depending on the order of discharging for selection.

At this time, the display gradation can be changed so that the same subfield as the subfield selected two rows later in the same column is selected in accordance with the order of discharging for selection.

Further, the display gradation can be changed so that the same subfield as the subfield selected by the adjacent cell in the same display row is selected. At this time, it is preferable to change the display gradation for each field to bring the average display gradation closer to the original gradation.

In the above, the discharge spaces may be connected between adjacent cells. However, even if there are barrier ribs, the discharge spaces are connected by the unevenness of the surface thereof.

In the present invention, by selecting the same subfield between adjacent cells whose discharge spaces are connected, the discharge probability of the adjacent cells due to the charged particles diffused from the cell in which the address discharge occurs first and the metastable. Can be increased, and the discharge delay time of address discharge can be shortened.

By selecting the subfield before the subfield selected by the adjacent cells connected to the discharge space, the adjacent cells are discharged by the charged particles and the metastable generated in the sustain discharge of the previous subfield. The probability increases, and the discharge delay time of the address discharge in the next subfield can be shortened.

As described above, the discharge delay time is shortened by utilizing the charged particles and the metastable generated in the address discharge or the sustain discharge of the adjacent cells which are connected to the discharge space or the adjacent cells. As a result, it is possible to prevent defective lighting due to the occurrence of no address discharge. Further, since the address discharge is generated at a high speed, the scanning pulse can be shortened and the scanning period can be shortened, so that the display period can be extended and the number of subfields can be increased.

Further, since no light is emitted in the non-display cell, the contrast is not deteriorated and only the subfield to be selected is changed, so that it is not necessary to change the driving circuit.

Further, the structure in which the stripe type partition walls and the barriers are added has been taken as an example, but even in the closed cell structure, adjacent cells may be formed due to a slight gap due to the unevenness of the dielectric layer and the partition surface. And the discharge space are connected,
The effect of shortening the discharge delay time can be obtained.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method of driving a plasma display according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

The basic structure of the plasma display panel driven in this embodiment is the same as that of the conventional plasma display panel shown in FIG. The partition wall 7 that separates the discharge space has a linear shape in the column direction,
It is a so-called stripe type. For this reason, the discharge spaces of adjacent cells are connected in the column direction. In addition, each column is painted in RGB, and all cells belonging to the same column have the same color.

The driving pulse applied to each electrode is also the same as in the conventional plasma display panel, and is a basic driving pattern for driving the plasma display panel in a subfield including a preliminary discharge period, a scanning period and a sustain period. One unit. In the cell to display,
During the scanning period, the data pulse is applied to the data electrode 6 in synchronization with the application timing of the scan pulse, and the scan electrode 2
Writing discharge occurs between the data electrode 6 and the data electrode 6. The number of subfields forming one field is 12, and the weighting of the number of sustain pulses in each subfield has the ratio shown in FIG. It is possible to express 256 gradations by combining 12 subfields.

Further, in scanning of each sub-field, scanning is performed sequentially from the upper cell to the lower cell in the drawing of FIG.

Next, a method of selecting subfields according to the display gradation will be described. However, a cell in m rows and n columns is expressed as a cell (m, n). The cell (m +
Consider the case where the gradation of 1, n + 1) is 24 and the gradation of the cell (m + 2, n + 1) is 1.

As in the conventional case, when the subfield is coded by giving priority to the lower bits, the selected subfield is as shown in FIG. However, the subfield marked with "●" in FIG. 1 is a selected subfield, and the address discharge and the sustain discharge are performed. Cell (m
+1, n + 1) has a gradation of 24, and SF3 + SF4 + SF5 is used as a combination of subfields.
On the other hand, the subfield selected by the cell (m + 2, n + 1) is SF1.

However, in this embodiment, the subfield coding is determined by the following algorithm. FIG. 2 is a schematic diagram showing a subfield selection method in this embodiment. For example, LUT
(0) 14a is the weight 24 of FIG.
And a table table (lookup table) including those represented by SF5. The LUT (1) 14b is a table that includes the weights 24 of FIG. 1B represented by SF1, SF2, and SF7. LUT (2) 14c and LUT
(3) 14d also represents the weight 24 by any one of SF1 to SF7.

First, when the sub-field coding circuit 11 shown in FIG. 2 receives an input grayscale signal, it determines whether the number of sustain pulses of the own cell is 10 or more. Next, the lower cell gradation evaluation circuit 13 determines whether SF1, SF2, and SF3 are independently selected in the cell immediately below. If both are applicable, it is determined whether or not it is possible to make the coding including the selected subfield in the immediately lower cell, and use that coding if possible. As described above, the subfield coding circuit 11 reads the LUT selection circuit 12 after driving the subfield selection signal after converting the input signal into the grayscale, similarly to the conventional subfield coding circuit 100 shown in FIG. Send to circuit 15.

The operation when such an algorithm is used will be described. Cell (m + 1, n + 1) has 10 or more sustain pulses, and cell (m + 2, n + 1)
The number of sustain pulses is less than 10. Then, SF1 is independently selected in the cell (m + 2, n + 1). At this time, in the cell (m + 1, n + 1), the gradation 24 can be expressed by SF1 + SF2 + SF7 including SF1, so this coding is adopted. As a result, the selected subfield is as shown in FIG.

The advantages of changing the coding in this way will be described below. Cell (m + 1, n + 1)
Then, the total number of sustain discharges in one field is large. For this reason, a large amount of charged particles and metastable generated in the sustain discharge are present in the discharge space in the cell, and the discharge probability is kept in a high state to some extent. As a result, the cell (m
In (+1, n + 1), the address discharge is generated at high speed in any subfield.

On the other hand, in the cell (m + 2, n + 1), SF1
Is selected independently, and the total number of sustain discharges in one field is small. Therefore, the discharge delay time in SF1 is large, and the address discharge may not occur within the scan pulse width.

However, even in the cell (m + 1, n + 1), the SF
By selecting 1, the charged particles and metastable generated in the address discharge of SF1 of the cell (m + 1, n + 1) are diffused into the discharge space of the cell (m + 2, n + 1), which increases the discharge probability. In particular, if charged particles are present in the discharge space, the discharge probability becomes extremely large. Immediately after that, since the row including this cell (m + 2, n + 1) is scanned, the discharge delay time of the address discharge of the cell (m + 2, n + 1) becomes small, and the discharge delay time when the original value is 1. , Up to about 0.4. The original value is a value when there is no influence from an adjacent cell.

According to the experiments conducted by the inventors of the present application, such an effect of speeding up is not limited to the case where the cell (m + 1, n + 1) immediately above is selected, and for example, the cell (m, n + 1) and the cell (m + 2). It could be confirmed even in the case of interposing a non-selected cell between the cells such as (n + 1). FIG. 3 is a graph showing the relationship between the number of non-selected cells and the discharge delay time of the lower cells when there is a non-selected cell between two selected cells.

That is, cell (m, n + 1) has gradation 24, cell (m + 1, n + 1) has gradation 12, and cell (m + 2, n +).
If 1) is gradation 1, cell (m + 1, n + 1)
SF1 cannot be selected with, but cell (m, n +
1), so that cells (m + 2, n +) can be selected.
It is possible to shorten the discharge delay time of the address discharge of SF1 of 1). In the actual operation, in the subfield selection operation of FIG. 2, the cells that determine whether SF1, SF2, and SF3 are independently selected are searched not only for the cells directly below but also the cells one below. To In the case of the above example, the cell (m + 1, n + 1) is SF1,
SF2 and SF3 are not independently selected, and cells (m +
2, n + 1), SF1 is selected alone, so
The coding is performed so that the cell (m + 2, n + 1) has priority. As a result, the result is as shown in FIG. By making this selection, as shown in FIG. 3, cells (m + 2, n +
In 1), the discharge delay time is shortened to about 0.7 times the normal time.

In the plasma display panel driven in this embodiment, all the cells in the column direction in which the discharge spaces are connected have the same color. In the actual image, the same color is often continuously selected in the neighboring dots, so that it is quite possible that the same subfield can be continuously selected or separated by one cell in the column direction. Video false contours may appear by changing the selected subfield, but since it is applied only to low bit subfields, the selection status at high bits with a large weight does not change, and video false The contour is not affected much.

As described above, according to the driving method of this embodiment, the average discharge delay time can be shortened, the stability of the address discharge is improved, and further, the sustain period is increased by shortening the scanning period. That is, high brightness can be realized.
In the present embodiment, the shape of the barrier rib 7 is a stripe shape, but the shape is not limited to this shape, and if the discharge spaces are connected in some way in the column direction, the effect of shortening the discharge delay time can be obtained. Is obtained.

Next, a second embodiment of the present invention will be described. In the first embodiment, the same subfield is selected in the column direction in the plasma display panel in which the discharge spaces of the adjacent cells are continuous in the column direction, but the discharge spaces of the adjacent cells are connected in the row direction. If so, the same subfield may be selected in the row direction. FIG. 5 is a diagram showing the structure of the plasma display panel of the second embodiment. As shown in FIG. 5, a barrier 9 extending in the row direction is provided on the insulating substrate 1a, and discharge spaces are connected in the row direction.

However, it is not necessary to positively connect the adjacent cells to the discharge space by the barrier 9.
Even in the plasma display panel shown in FIG. 2, the discharge spaces can be connected in the row direction by providing a slight gap due to the unevenness on the surface of the dielectric layer 4a. This will be described with reference to the plan view of FIG. Cell (m + 1, n + 1) has gradation 1, cell (m + 1, n + 2)
Consider that the gradation is 24.

As in the conventional case, when the subfield is coded by giving priority to the lower bits, the cell (m + 1, n
The subfield selected in +2) is SF3 + SF4 +
SF5. On the other hand, the subfield selected by the cell (m + 1, n + 1) is SF1.

In this case, in the first embodiment, it is determined whether or not the number of sustain pulses of the own cell is 10 or more, and if it is the case, SF1, SF2, SF in the cells immediately below are determined.
It is determined whether or not 3 is selected independently. In the second embodiment, SF is determined by adjacent cells in the row direction.
It is determined whether 1, SF2 and SF3 are independently selected. If so, it is determined whether or not coding including the subfield selected in the adjacent cell is possible, and if possible, that coding is used.

When such an algorithm is used, the number of sustain pulses is 10 or more in the cell (m + 1, n + 2), and SF1 is independently selected in the cell (m + 1, n + 1). At this time, in the cell (m + 1, n + 2), SF
Since it is possible to express the gray scale 24 with SF1 + SF2 + SF7 including 1, the coding is adopted.
As a result, the selected subfields are as shown in FIG.

Since the cell (m + 1, n + 2) has a large number of sustain discharges in the field, the address discharge is always generated with a high discharge probability. Therefore, the cell (m +
In general, (1, n + 2) discharges before the cell (m + 1, n + 1). The discharge probability of the cell (m + 1, n + 1) is low initially, but an address discharge is generated in the cell (m + 1, n + 2), and the charged particles and metastable generated by this address discharge are diffused in the cell (m + 1, n + 1). By doing so, the discharge probability increases.

In this way, the average discharge probability within the scan pulse period is increased, so that the discharge delay time is shortened. According to this method, even if the same color is not continuously selected in the column direction, if the cells are continuously selected in the row direction, the discharge delay time can be shortened. Furthermore,
When discharge spaces are connected between adjacent cells in both the row and column directions, the selection width of the subfields, that is, the degree of freedom, can be obtained by combining the selected subfields in the cells in the row and column directions. Can be very large.

Next, a third embodiment of the present invention will be described. A third embodiment will be described with reference to the plasma display panel of FIG. 10 in which the discharge spaces are connected in the column direction and FIG. 11 which is a plan view thereof.

In this case, subfield coding when the cell (m + 1, n + 1) has the gradation 2 and the cell (m + 2, n + 1) has the gradation 22 will be described. As in the conventional case, when subfield coding is performed by giving priority to lower bits, the subfield selected in the cell (m + 2, n + 1) is SF2 + SF4 + SF5. On the other hand, the subfield selected by the cell (m + 1, n + 1) is SF2.

In the third embodiment, SF1, SF2, SF3 are set in all the adjacent cells connected to the discharge space.
Is selected by itself. If applicable, it is determined whether or not coding including the preceding subfield is possible, and if so, that coding is used. In this case, as for SF1, SF12 of the previous field becomes the previous subfield.

When such an algorithm is used, it is assumed that the number of sustain pulses is 10 or more in the cell (m + 2, n + 1) and less than 10 in the cell (m + 1, n + 1). Further, in the cell (m + 1, n + 1), SF2 is independently selected. At this time, in the cell (m + 2, n + 1), since it is possible to express the gradation 22 by SF1 + SF7 including SF1 which is the subfield immediately before SF2, this coding is adopted. As a result, the selected subfields are those shown in FIG.

Next, the advantages of changing the coding will be described. Cell (m + 2, n +
In 1), the gradation is 22, and the total number of sustain pulses in one field is large, so the discharge probability is high, and the discharge delay time is small in any subfield. on the other hand,
Since the gray level is low in the cell (m + 1, n + 1), the total number of sustain pulses in one field is small. Therefore, this SF
The discharge delay time of 2 is large.

However, since the subfield SF1 before SF2 is selected in the cell (m + 2, n + 1) and sustain discharge is performed many times, a large amount of charged particles and metastable are stored in the discharge space. . These also diffuse to neighboring cells. Since the charged particles have a short lifetime, the number thereof is reduced immediately. However, since the metastable has a relatively long lifetime, it sufficiently exists in the scanning period of the next subfield SF2. Therefore, the discharge probability is also kept high, and the discharge delay time of the address discharge is shortened.

As described above, when the same subfield cannot be selected between the adjacent cells, the previous subfield is selected and the sustain discharge is performed to generate the charged particles and the metastable. The discharge probability of the cell can be increased. In addition, this method can be used regardless of the scanning order regardless of the row direction or the column direction as long as the cells are connected to the discharge space regardless of the row direction and the column direction. Furthermore, when combined with the methods of the first and second embodiments, the range of choice is extremely wide.

Next explained is the fourth embodiment of the invention. The fourth embodiment will be described with reference to the plasma display panel of FIG. 10 in which the discharge spaces are connected in the column direction and FIG. 11 which is a plan view thereof. Cell (m +
1, n + 1) has a gradation of 12, and cells (m + 2, n +)
Consider the case where the gradation of 1) is 1.

When the same subfield coding as in the conventional case is performed, the subfield selected by the cell (m + 1, n + 1) is SF3 + SF4, and the cell (m +
The subfield selected by (2, n + 1) is SF1. However, in the cell (m + 1, n + 1), SF1
You cannot choose the coding that you choose.

In such a case, cells (m + 2, n +
SF1 selected in 1) is the cell (m
+1, n + 1) will be selected.

As a result, the same subfield is continuously selected between the adjacent cells whose discharge spaces are connected, and the cells (m + 2, n) are selected as in the first embodiment.
The address discharge of SF1 of +1) is generated at high speed. In FIG. 8, “◯” is the subfield selected and added.

At this time, if the original gradation of the cell to which the subfield is added is large, even if a subfield having a small gradation is added, the rate of change in gradation is small, so there is little effect on appearance. .

However, when it is necessary to correct the collapsed gradation, the gradation for SF1 added in the cell (m + 1, n + 1) is reduced in the field next to the selected field. That is, in the next field, the cell (m +
1, n + 1) has a gradation of 11, and SF1 + SF2 + SF
Select 4. As a result, the same gradation level as that of the original image is maintained as the average of the two fields. Furthermore, in any field, the cell (m +
Since SF1 is selected by 1, n + 1), the cell (m +
(2, n + 1) SF1 writing is accelerated. For gradation correction, interpolation may be performed not only in two fields but in a plurality of fields larger than that.

In this way, whether adjacent cells are the same,
Alternatively, even if the previous subfield cannot be selected, the discharge delay time of the address discharge due to the selection of the same subfield can be shortened by temporarily changing the gradation.

By properly combining the methods described above, the selection range for shortening the discharge delay time of the address discharge for each cell is further widened, and the discharge delay time as an average value can be shortened. Becomes

The present invention is not limited to the above embodiment, but various modifications can be made. For example, the present invention is effective not only for the driving method in which the scanning period and the sustain period are separated temporally but also for the driving method in which the writing period and the sustain period for each display line are not temporally separated. Needless to say.

The present invention is also an effective method not only in the case of line-sequential scanning but also in the interlaced scanning of one line in which odd lines and even lines are sequentially scanned.

Further, in each of the above-mentioned embodiments, the structure in which the stripe type partition 7 and the barrier 9 are added is taken as an example. However, as shown in FIG. 9, a closed type having partition extending in the row direction and the column direction is provided. Even in the cell structure of, due to a slight gap due to the unevenness of the surface of the dielectric layer 4a and the partition wall 7,
Since the adjacent cells and the discharge space are connected, the effect of shortening the discharge delay time can be obtained.

[0089]

As described above, the present invention has the following effects. That is, by selecting the same subfield between adjacent cells having discharge spaces connected to each other, the discharge probability of the adjacent cells is increased by the charged particles and metastable diffused from the cell in which the address discharge occurs first, and the address discharge is increased. The discharge delay time can be shortened.

By selecting the subfield before the subfield selected by the adjacent cells connected to the discharge space, the adjacent cells are discharged by the charged particles and the metastable generated by the sustain discharge of the previous subfield. The probability increases, and the discharge delay time in the address discharge of the next subfield can be shortened.

As described above, according to the present invention, the discharge delay can be achieved by using the charged particles and the metastable generated by the address discharge or the sustain discharge of the adjacent cells to which the discharge spaces are connected or the adjacent cells. Save time. This allows
It is possible to prevent defective lighting caused by the non-occurrence of address discharge. Further, since the address discharge is generated at a high speed, the scanning pulse can be shortened and the scanning period can be shortened, so that the display period can be extended and the number of subfields can be increased.

Further, since no light is emitted in the non-display cell, the contrast is not deteriorated,
It is not necessary to change the driving circuit because only the subfield to be selected is changed.

[Brief description of drawings]

FIG. 1 is a diagram showing subfield selection according to the first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an operation for determining subfield coding.

FIG. 3 is a graph showing the effect of shortening the discharge delay time in the first embodiment of the present invention.

FIG. 4 is a diagram showing selection of subfields according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view of a main part of a plasma display using a barrier extending in the row direction.

FIG. 6 is a diagram showing subfield selection in the second embodiment of the present invention.

FIG. 7 is a diagram showing selection of subfields according to the third embodiment of the present invention.

FIG. 8 is a diagram showing subfield selection in the fourth embodiment of the present invention.

FIG. 9 is a cross-sectional view of essential parts of a plasma display having a closed cell structure.

FIG. 10 is a cross-sectional view of a main part of a plasma display.

FIG. 11 is a view of the plasma display as viewed from the display surface side.

FIG. 12 is a diagram showing a scan-maintenance-separation-type drive sequence.

FIG. 13 is a diagram in which one field is divided into 12 subfields.

FIG. 14 is a diagram showing a weighting array of subfields.

FIG. 15 is a schematic diagram showing an operation for determining coding of a conventional subfield.

[Explanation of symbols]

1a, 1b; insulating substrate 2; Scan electrode 3; sustaining electrode 4a, 4b; dielectric layer 5; Protective film 6; Data electrode 7; Partition wall 8: phosphor 9; Barrier 11, 100; Subfield coding circuit 12; LUT selection circuit 15, 102; drive circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/288 G09G 3/28 K H04N 5/66 101 B (72) Inventor Yoshito Tanaka Shiba, Minato-ku, Tokyo 5-7-1 NEC Corporation (72) Inventor Hajime Honma Hajime Honma 5-7-1 Shiba, Minato-ku, Tokyo F-Term (5) C558 AA11 BA35 BB25 5C080 AA05 BB05 DD08 DD09 EE29 FF12 HH02 JJ02 JJ04 JJ06

Claims (14)

[Claims] 1. A method of driving a plasma display panel, wherein one field is divided into a plurality of subfields having at least a plurality of types of luminance weighting, and gradation display is performed by individually selecting display of each subfield. And a method of driving a plasma display panel, wherein the selection of subfields for display gradation is changed according to the selection state of subfields of adjacent cells. 2. Depending on the order of performing the discharge for selection,
The driving method of the plasma display panel according to claim 1, wherein the selection state of the subfield is changed so that the same subfield as the subfield selected in the next row in the same column is preferentially selected. . 3. According to the order of performing discharge for selection,
2. The driving method of the plasma display panel according to claim 1, wherein the selection state of the subfield is changed so that the same subfield selected after two rows in the same column is preferentially selected. . 4. The driving method of the plasma display panel according to claim 2, wherein the discharge for selection is performed line-sequentially continuously with respect to the display rows. 5. The driving method of the plasma display panel according to claim 3, wherein the discharge order for selection is every other display row. 6. The method of driving a plasma display panel according to claim 1, wherein the same subfield as a subfield selected by adjacent cells in the same display row is preferentially selected. 7. The method of driving a plasma display panel according to claim 2, wherein the selection state is changed so that the same subfield is selected only for the subfields with low weighting. . 8. The plasma display panel according to claim 1, wherein a selection state of subfields is changed so that a subfield before a subfield selected by adjacent cells is preferentially selected. Driving method. 9. The driving method of the plasma display panel according to claim 8, wherein the subfield selection state is changed when the subfields selected in adjacent cells are subfields having a low weighting. 10. The display gradation is changed so that the same subfield as the subfield selected in the next row in the same column is selected according to the order of discharging for selection. The driving method of the plasma display panel according to claim 1. 11. The display gradation is changed so that the same subfield as a subfield selected two rows later in the same column is selected according to the order of discharging for selection. The driving method of the plasma display panel according to claim 1. 12. The plasma display panel according to claim 1, wherein the display gradation is changed so that the same subfield is selected as a subfield selected by an adjacent cell in the same display row. Driving method. 13. A display gradation is changed for each field,
13. The method for driving a plasma display panel according to claim 10, wherein an average display gradation is brought close to an original gradation. 14. The method of driving a plasma display panel according to claim 1, wherein discharge spaces are connected between adjacent cells.