KR20130043224A - Plasma display device drive method and plasma display device - Google Patents

Abstract

In the plasma display device, the effect of suppressing crosstalk is enhanced. To this end, in the display combination set configured by selecting a plurality of combinations of the light emitting subfields and the non-light emitting subfields, the number of combinations of the first display combination set and the light emitting subfields and the non-light emitting subfields is the first. The gray scale is displayed on the plasma display panel by including a second display combination set that is smaller than the display combination set. The first set of combinations for display is used to convert the gradation values of the discharge cells having relatively large electrode widths of the data electrodes into image data. In addition, when converting the gradation values of the discharge cells with relatively narrow electrode widths of the data electrodes into image data, the first display combination set or the second display combination set is used.

Description

Plasma display device driving method and plasma display device {PLASMA DISPLAY DEVICE DRIVE METHOD AND PLASMA DISPLAY DEVICE}

The present invention relates to a driving method and a plasma display device of a plasma display device using an AC surface discharge type plasma display panel.

In the AC surface discharge type panel typical as a plasma display panel (hereinafter abbreviated as "panel"), a large number of discharge cells are formed between the front substrate and the rear substrate which are disposed to face each other. In the front substrate, a plurality of pairs of display electrode pairs comprising a pair of scan electrodes and sustain electrodes are formed in parallel with each other on the glass substrate on the front side. A dielectric layer and a protective layer are formed to cover these display electrode pairs.

In the back substrate, a plurality of parallel data electrodes are formed on the glass substrate on the back side, a dielectric layer is formed to cover these data electrodes, and a plurality of partition walls are formed on the back substrate in parallel with the data electrodes. The phosphor layer is formed on the surface of the dielectric layer and the side surfaces of the partition wall.

Then, the front substrate and the rear substrate are disposed to face each other so that the display electrode pair and the data electrode are three-dimensionally intersected. In the sealed interior discharge space, for example, a discharge gas containing xenon having a partial pressure ratio of 5% is sealed, and a discharge cell is formed at a portion where the display electrode pair and the data electrode face each other. In the panel having such a configuration, ultraviolet rays are generated by gas discharge in each discharge cell, and the ultraviolet rays are excited to emit phosphors of each color of red (R), green (G), and blue (B), and the colored Image display is performed.

As a method of driving the panel, a subfield method is generally used. In the subfield method, gradation display is performed by dividing one field into a plurality of subfields and setting each discharge cell to light emission or non-light emission in each subfield. Each subfield has an initialization period, a writing period, and a sustaining period.

In the initialization period, an initialization waveform is applied to each scan electrode, and an initialization operation is performed to generate initialization discharge in each discharge cell. As a result, in each discharge cell, the wall charges necessary for subsequent write operations are formed, and priming particles (excitation particles for generating discharge) are generated to stably generate the write discharges.

In the write period, scan pulses are sequentially applied to the scan electrodes, and write pulses are selectively applied to the data electrodes based on the image signal to be displayed. Thereby, write discharge is generated between the scan electrode and the data electrode of the discharge cell to emit light, and wall charges are formed in the discharge cell (hereinafter, these operations are collectively referred to as " write ").

In the sustain period, the number of sustain pulses based on the luminance weight determined for each subfield is alternately applied to the display electrode pair consisting of the scan electrode and the sustain electrode. As a result, sustain discharge is generated in the discharge cell in which the write discharge is generated, and the phosphor layer of the discharge cell is caused to emit light (hereinafter, "lighting" means that the discharge cell emits light by sustain discharge, "non-lighting"). Also write). This causes each discharge cell to emit light at a luminance corresponding to the luminance weight. In this way, each discharge cell of the panel is made to emit light at luminance corresponding to the gradation value of the image signal, thereby displaying an image in the image display area of the panel.

In a plasma display device using such a panel, a phenomenon may occur in which charges move from one discharge cell to another discharge cell between adjacent discharge cells. Hereinafter, such a phenomenon is called "cross talk." When crosstalk occurs, the wall charge in the discharge cell is reduced. Then, when the discharge cells in which the writing operation becomes unstable due to the reduction of the wall charges due to the crosstalk occur, the image display quality may deteriorate.

In order to prevent deterioration of image display quality in a plasma display apparatus, the technique of preventing crosstalk is disclosed (for example, refer patent document 1). In the technique described in this patent document 1, only a specific gradation value is used when displaying an image on a panel. This specific gradation value is a gradation value having a light emission pattern in which light emission and non-emission of the subfield are not replaced in successive subfields between successive grayscale values.

In the method described in Patent Document 1, an effect can be obtained with respect to crosstalk generated between discharge cells (adjacent discharge cells sharing one data electrode) adjacent in the column direction. However, it is difficult to obtain sufficient effects on the crosstalk generated between the discharge cells adjacent to each other in the row direction (adjacent discharge cells sharing a pair of display electrode pairs).

In addition, when the panel becomes high resolution, the interval of the discharge cells adjacent in the row direction becomes narrow. Therefore, in a panel having a high resolution, crosstalk is more likely to occur. Therefore, there is a demand for a plasma display device that can increase the effect of suppressing crosstalk and also suppress the effect of crosstalk on an image displayed on a panel when crosstalk occurs.

(Prior art technical literature)

(Patent Literature)

(Patent Document 1) Japanese Unexamined Patent Application Publication No. 2004-29265

The present invention comprises a plurality of display combination sets comprising one field composed of a plurality of subfields with predetermined luminance weights, and a plurality of combinations of light emitting subfields and non-light emitting subfields. The light emission and non-emission of the discharge cells are controlled using a combination belonging to a combination set of components for forming a gray scale on a plasma display panel having a plurality of discharge cells each having a data electrode having a width different from that of a display electrode pair consisting of a scan electrode and a sustain electrode. A driving method of a plasma display device for displaying. In this driving method, a display combination set having a first display combination set and a second display combination set in which the number of combinations of light emitting subfields and non-light emitting subfields is smaller than the first display combination set is used. The gray scale is displayed on the plasma display panel. The first set of combinations for display is used to convert the gradation values of the discharge cells having relatively large electrode widths of the data electrodes into image data. In addition, when converting the gradation values of the discharge cells with relatively narrow electrode widths of the data electrodes into image data, the first display combination set or the second display combination set is used.

Thereby, while increasing the effect of suppressing crosstalk, when crosstalk occurs, the influence of crosstalk on the image displayed on the panel can be suppressed, and a high quality image can be displayed on the panel.

In addition, in the driving method of the plasma display device of the present invention, when converting the gradation value of the discharge cell of which the electrode width of the data electrode is relatively narrow into image data, at least one gradation value of other discharge cells is set in advance. If it is more than a threshold, it is preferable to use a combination set for the second display.

Further, in the method of driving the plasma display apparatus of the present invention, the first display combination set and the second display combination set emit light so that the subfield after the specific subfield does not emit light unless the specific subfield emits light. The combination of the subfield and the non-emitting subfield is selected. The number of specific subfields in the second display combination set is made larger than the number of specific subfields in the first display combination set.

In addition, in the driving method of the plasma display device of the present invention, the color of the discharge cells having a relatively narrow electrode width of the data electrode may be blue.

In the method of driving the plasma display device of the present invention, the colors emitted by the discharge cells of which the electrode width of the data electrode is relatively narrow may be blue and red.

The present invention also provides a plasma display panel including a plurality of discharge cells each having a data electrode having a width different from that of a display electrode pair consisting of a scan electrode and a sustain electrode, a display period, and a number of sustain pulses corresponding to luminance weights. A plurality of subfields having a sustain period applied to the pair are configured to drive a plasma display panel, and a plurality of display combination sets are provided by selecting a plurality of combinations of light emitting subfields and non-light emitting subfields. And a driving circuit for controlling the light emission and non-emission of the discharge cells to display gray scales using a combination belonging to a display combination set. In the plasma display device, the driving circuit is for display having a first display combination set and a second display combination set in which the number of combinations of light emitting subfields and non-light emitting subfields is smaller than that of the first display combination set. The gray scale is displayed on the plasma display panel using the combination set. The first set of combinations for display is used to convert the gradation values of the discharge cells having relatively large electrode widths of the data electrodes into image data. In addition, when converting the gradation values of the discharge cells with relatively narrow electrode widths of the data electrodes into image data, the first display combination set or the second display combination set is used.

Thereby, while increasing the effect of suppressing crosstalk, when crosstalk occurs, the influence of crosstalk on the image displayed on the panel can be suppressed, and a high quality image can be displayed on the panel.

1 is an exploded perspective view showing the structure of a panel used for the plasma display device according to the first embodiment of the present invention.
2 is an electrode array diagram of a panel used in the plasma display device according to the first embodiment of the present invention.
3 is a schematic diagram showing an enlarged arrangement of discharge cells and data electrodes of a panel used in the plasma display device according to Embodiment 1 of the present invention.
4 is a diagram schematically showing a drive voltage waveform applied to each electrode of a panel used in the plasma display device according to the first embodiment of the present invention.
5A is a diagram illustrating an example of a first coding table used for the plasma display device according to the first embodiment of the present invention.
5B is a diagram illustrating an example of a second coding table used for the plasma display device according to the first embodiment of the present invention.
6 is a diagram schematically showing an example of a circuit block constituting the plasma display device according to the first embodiment of the present invention.
7 is a diagram schematically showing an example of the configuration of an image signal processing circuit used in the plasma display device according to the first embodiment of the present invention.
8 is a diagram showing a minimum value of the write pulse voltage Vd required for the write operation in each subfield.
FIG. 9A is a diagram showing an example of a light emission pattern in which the writing operation in the blue discharge cell is likely to become unstable in the plasma display device 40 according to Embodiment 1 of the present invention.
FIG. 9B is a diagram illustrating another example of the light emission pattern in which the writing operation in the blue discharge cell is unstable in the plasma display device 40 according to the first embodiment of the present invention.
Fig. 10 is a schematic diagram showing an enlarged arrangement of discharge cells and data electrodes of a panel used in the plasma display device according to the second embodiment of the present invention.
FIG. 11 is a diagram schematically showing an example of the configuration of an image signal processing circuit used in the plasma display device according to the second embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the plasma display apparatus in embodiment of this invention is demonstrated using drawing.

(Embodiment Mode 1)

1 is an exploded perspective view showing the structure of the panel 10 used in the plasma display device according to the first embodiment of the present invention. On the glass front substrate 21, the display electrode pair 24 which consists of the scanning electrode 22 and the sustain electrode 23 is formed in multiple numbers. The dielectric layer 25 is formed to cover the scan electrode 22 and the sustain electrode 23, and a protective layer 26 is formed on the dielectric layer 25.

The protective layer 26 has been used as a material for the panel in order to lower the discharge start voltage in the discharge cell, and when the neon (Ne) and xenon (Xe) gases are encapsulated, the secondary electron emission coefficient is It is formed of a material containing magnesium oxide (MgO), which is large and excellent in durability.

A plurality of data electrodes 32 are formed on the rear substrate 31, a dielectric layer 33 is formed to cover the data electrodes 32, and a well-shaped partition wall 34 is formed thereon. The phosphor layer 35R emitting red (R), the phosphor layer 35G emitting green (G), and the phosphor layer emitting blue (B) are disposed on the side surface of the barrier rib 34 and the dielectric layer 33. 35B is provided. Hereinafter, the phosphor layer 35R, the phosphor layer 35G, and the phosphor layer 35B are collectively referred to as the phosphor layer 35.

These front substrates 21 and rear substrates 31 are disposed to face each other so that the display electrode pairs 24 and the data electrodes 32 cross each other with a small discharge space therebetween. And the outer peripheral part is sealed by sealing materials, such as glass frit. Then, for example, a mixed gas of neon and xenon is sealed as the discharge gas in the discharge space therein.

The discharge space is divided into a plurality of sections by the partition wall 34, and discharge cells are formed at portions where the display electrode pairs 24 and the data electrodes 32 cross each other.

Discharges are generated in these discharge cells, and the phosphor layer 35 of the discharge cells emits light (lights the discharge cells), thereby displaying a color image on the panel 10.

In the panel 10, one pixel is constituted by three consecutive discharge cells arranged in a direction in which the display electrode pairs 24 extend. These three discharge cells are discharge cells (red discharge cells) having a phosphor layer 35R and emitting red (R), and discharge cells (green) having a phosphor layer 35G and emitting green (G). Discharge cell) and a discharge cell (blue discharge cell) that emits blue light with the phosphor layer 35B.

In addition, the structure of the panel 10 is not limited to the above-mentioned thing, For example, you may be provided with the stripe-shaped partition.

2 is an electrode arrangement diagram of the panel 10 used in the plasma display device according to the first embodiment of the present invention. The panel 10 has n scan electrodes SC1 to SCn (scan electrode 22 in FIG. 1) and n sustain electrodes SU1 to sustain electrode SUn (storage electrode in FIG. 1) extending in the horizontal direction (row direction). (23) are arranged, and m data electrodes D1 to Dm (data electrodes 32 in FIG. 1) extending in the vertical direction (column direction) are arranged.

A discharge cell is formed at a portion where a pair of scan electrodes SCi (i = 1 to n) and sustain electrode SUi intersect with one data electrode Dj (j = 1 to m). That is, m discharge cells are formed on the pair of display electrode pairs 24, and m / 3 pixels are formed. Then, m x n discharge cells are formed in the discharge space, and an area in which m x n discharge cells are formed is an image display area of the panel 10. For example, in a panel having 1920 × 1080 pixels, m = 1920 × 3, and n = 1080.

For example, a red phosphor is applied as the phosphor layer 35R to a discharge cell having a data electrode Dp (p = 3 × q-2: q is an integer except 0 of m / 3 or less), and the data electrode Dp + A green phosphor is applied as the phosphor layer 35G to the discharge cell having 1, and a blue phosphor is applied as the phosphor layer 35B to the discharge cell having the data electrode Dp + 2.

3 is a schematic diagram showing an enlarged arrangement of discharge cells and data electrodes of a panel used in the plasma display device according to Embodiment 1 of the present invention.

As shown in FIG. 3, in the present embodiment, in the panel 10, the electrode widths of the data electrodes 32 constituting the red discharge cells and the green discharge cells are relatively wide, and blue discharge cells are formed. The electrode width of the constituent data electrodes 32 is relatively narrow. Thus, the reason for providing a difference in the electrode width of the data electrode 32 in accordance with the light emission color of the discharge cell will be described later. In the panel 10, for example, the electrode width of the data electrode 32 constituting the red discharge cell and the green discharge cell is about 90 μm, and the data electrode 32 constituting the blue discharge cell is shown. The electrode width is about 70 mu m.

In the present embodiment, the "first color" and the "second color" are set based on the electrode width of the data electrode 32. Specifically, a color in which the discharge cells having a relatively wide electrode width emit light emits light as a “first color”, and a color in which the discharge cells having a relatively narrow electrode width emit light emits light. Let it be "second color." In the example shown in FIG. 3, "first color" is red and green, and "second color" is blue.

Next, the outline | summary of the drive voltage waveform and the operation | movement for driving the panel 10 is demonstrated.

The plasma display device according to the present embodiment drives the panel 10 by the subfield method. In the subfield method, one field is divided into a plurality of subfields on the time axis, and luminance weights are set in each subfield. Thus, each field has a plurality of subfields each. Each subfield has an initialization period, a writing period, and a sustaining period.

In the present embodiment, one field is composed of six subfields (subfield SF1, subfield SF2, subfield SF3, subfield SF4, subfield SF5, subfield SF6), and the subfield SF1 to subfield. Each subfield of SF6 describes an example having luminance weights of (1, 2, 4, 8, 16, 32), respectively.

However, in the present invention, the number of subfields constituting one field, the luminance weight of each subfield, and the like are not limited to the above numerical values. For example, one field is composed of 10 subfields (subfield SF1, ..., subfield SF10), and each subfield of subfield SF1 to subfield SF10 is (1, 2, 3, 6, 11, 18, 30), respectively. It is preferable to appropriately set the configuration of the subfield in accordance with the specification of the plasma display device or the like, having a luminance weight of 44, 60, 81, and the like.

In the initialization period, an initialization discharge is generated in the discharge cells, and an initialization operation is performed in which wall charges necessary for the write discharge in the subsequent writing period are formed on each electrode.

In the write period, a scan pulse is applied to the scan electrode 22 and a write pulse is selectively applied to the data electrode 32 to selectively generate a write discharge in the discharge cells to emit light. Then, a write operation is performed in which wall charges for generating sustain discharge are formed in the discharge cell in the subsequent sustain period.

In the sustain period, sustain pulses of the number obtained by multiplying the luminance weights set in the respective subfields by a predetermined proportional constant are alternately applied to the scan electrodes 22 and the sustain electrodes 23 to generate write discharges in the immediately preceding write periods. A sustain discharge is generated in the discharge cells thus produced, and a sustain operation for causing the discharge cells to emit light is performed. This proportionality constant is a multiple of luminance.

The luminance weight indicates a ratio of the magnitude of luminance displayed in each subfield, and in each subfield, a number of sustain pulses corresponding to the luminance weight is generated in the sustain period. Therefore, for example, the subfield of luminance weight "8" emits light at about eight times the luminance of the subfield of luminance weight "1", and emits at about four times the luminance of the subfield of luminance weight "2". .

For example, when the luminance multiple is twice, the sustain pulse is applied to the scan electrode 22 and the sustain electrode 23 four times in the sustain period of the subfield having the luminance weight "2". Therefore, the number of sustain pulses generated in the sustain period is eight.

In this way, by controlling the light emission and non-emission of each discharge cell for each subfield in a combination according to the image signal to selectively light each subfield, various gray scale values can be displayed and an image can be displayed on the panel 10. Can be.

In addition, in the initialization operation, the entire cell initialization operation for generating the initialization discharge in the discharge cells irrespective of the operation of the immediately preceding subfield, the write discharge is generated in the writing period of the immediately preceding subfield, and the sustain discharge is generated in the sustaining period. There is a selective initialization operation to selectively generate an initialization discharge only in the discharge cell. In the all-cell initializing operation, the rising rising ramp waveform voltage and the falling falling ramp waveform voltage are applied to the scan electrode 22 to generate initialization discharge in all the discharge cells in the image display area. Then, among the plurality of subfields, all cell initialization operations are performed in the initialization period of one subfield, and selective initialization operation is performed in the initialization period of another subfield. Hereinafter, the initialization period which performs all-cell initialization operation is described as "all-cell initialization period", and the subfield which has all-cell initialization period is described as "all-cell initialization subfield." In addition, the initialization period which performs a selection initialization operation is described as "selection initialization period," and the subfield which has a selection initialization period is described as "selection initialization subfield."

In this embodiment, the first subfield (subfield SF1) of each field is used as the all-cell initialization subfield, and the other subfields are selected initialization subfields.

As a result, the initializing discharge is generated in all the discharge cells at least once in one field, so that the write operation after the all-cell initializing operation can be stabilized. In addition, light emission irrespective of the display of the image becomes only light emission in accordance with the discharge of the all-cell initializing operation in the subfield SF1. Therefore, the black luminance, which is the luminance of the black display region that does not generate sustain discharge, is only weak light emission in the whole cell initialization operation, and it is possible to display an image with high contrast on the panel 10.

However, in the present embodiment, the number of subfields constituting one field and the luminance weight of each subfield are not limited to the numerical values described above. In addition, the structure which switches a subfield structure based on an image signal etc. may be sufficient.

4 is a diagram schematically showing a driving voltage waveform applied to each electrode of the panel 10 used in the plasma display device according to the first embodiment of the present invention. 4 shows scan electrode SC1 performing the first writing operation in the writing period, scan electrode SCn performing the last writing operation in the writing period (for example, scanning electrode SC1080), sustain electrode SU1 to sustain electrode SUn, and data electrode D1. The drive voltage waveforms applied to each of the data electrodes Dm are shown. In addition, scan electrode SCi, sustain electrode SUi, and data electrode Dk below represent the electrode selected based on image data (data showing light emission and non-emission light for every subfield) among each electrode.

4 shows driving voltage waveforms of three subfields of a subfield SF1, a subfield SF2, and a subfield SF3. The subfield SF1 is a subfield for performing all cell initialization operations, and the subfield SF2 and subfield SF3 are subfields for performing a selective initialization operation. Therefore, in the subfield SF1, the subfield SF2 and the subfield SF3, the waveform shape of the drive voltage applied to the scan electrode 22 in the initialization period is different. The driving voltage waveforms in the other subfields are almost the same as the driving voltage waveforms of the subfield SF2 and the subfield SF3 except that the number of generation of sustain pulses in the sustain period is different.

In the present embodiment, the number of subfields constituting one field and the luminance weight of each subfield are not limited to the above values.

First, the subfield SF1 which is the all cell initialization subfield will be described.

In the first half of the initialization period of the subfield SF1 performing the all-cell initialization operation, a voltage of 0 V is applied to the data electrodes D1 to Dm and the sustain electrodes SU1 to SUn, respectively. After the voltage 0 (V) is applied to the scan electrodes SC1 to SCn, the voltage Vi1 is applied, and a rising ramp waveform voltage (lamp voltage) gradually rising from the voltage Vi1 to the voltage Vi2 is applied. The voltage Vi1 is set to a voltage lower than the discharge start voltage with respect to the sustain electrode SU1 to the sustain electrode SUn, and the voltage Vi2 is set to a voltage that exceeds the discharge start voltage.

While the ramp voltage is rising, between scan electrodes SC1 through SCn and sustain electrodes SU1 through SUn of each discharge cell, and between scan electrodes SC1 through SCn and data electrodes D1 through Dm. Each weak initializing discharge is generated continuously. A negative wall voltage is accumulated on scan electrodes SC1 through SCn, and a positive wall voltage is accumulated on data electrodes D1 through Dm and sustain electrodes SU1 through SUn. The wall voltage on the electrode refers to a voltage generated by wall charges accumulated on the dielectric layer, the protective layer, the phosphor layer, or the like covering the electrode.

In the second half of the initialization period of the subfield SF1, the positive voltage Ve1 is applied to the sustain electrodes SU1 through SUn, and the voltage 0 (V) is applied to the data electrodes D1 through Dm. A falling ramp waveform voltage (lamp voltage) that gently falls from the voltage Vi3 toward the negative voltage Vi4 is applied to the scan electrodes SC1 to SCn. The voltage Vi3 is set to a voltage which becomes less than a discharge start voltage with respect to sustain electrode SU1-the sustain electrode SUn, and voltage Vi4 is set to the voltage exceeding a discharge start voltage.

While applying this ramp voltage to scan electrodes SC1 to SCn, between scan electrodes SC1 to SCn and sustain electrodes SU1 to sustain electrodes SUn of each discharge cell, and scan electrodes SC1 to SCn and data electrodes D1. Weak initialization discharge occurs between the data electrodes Dm, respectively. The negative wall voltage on scan electrodes SC1 to SCn and the positive wall voltage on sustain electrodes SU1 to SUn are weakened, and the positive wall voltage on data electrodes D1 to Dm is adjusted to a value suitable for the write operation.

By the above, the all-cell initializing operation | movement in the initialization period of sub-field SF1 is complete | finished, and the wall charge necessary for the following writing operation | movement is formed on each electrode in all the discharge cells.

In the subsequent writing period of the subfield SF1, voltage Ve2 is applied to sustain electrode SU1 through sustain electrode SUn, voltage 0 (V) is applied to data electrode D1 through data electrode Dm, and voltage Vc is applied to scan electrode SC1 through scan electrode SCn. Apply.

Next, the negative scanning pulse of negative voltage Va is applied to the scanning electrode SC1 of the 1st line which performs a writing operation for the first time. Hereinafter, this voltage Va is also described as "scan pulse voltage." Then, a positive write pulse of positive voltage Vd is applied to the data electrode Dk of the discharge cell to emit light in the first row of the data electrodes D1 to Dm. Hereinafter, this voltage Vd is also described as "write pulse voltage."

In the discharge cell at the intersection of the data electrode Dk to which the write pulse voltage Vd is applied and the scan electrode SC1 to which the scan pulse voltage Va is applied, a discharge is generated between the data electrode Dk and the scan electrode SC1.

In addition, since the voltage Ve2 is applied to the sustain electrode SU1 to the sustain electrode SUn, the sustain electrode SU1 and the scan electrode which are caused by the discharge generated between the data electrode Dk and the scan electrode SC1 and intersect the data electrode Dk. Discharge also occurs between SC1. In this way, a write discharge occurs in the discharge cell (discharge cell to emit light) to which the scan pulse voltage Va and the write pulse voltage Vd were simultaneously applied, a positive wall voltage is accumulated on scan electrode SC1, and negative on sustain electrode SU1. The wall voltage is accumulated, and negative wall voltage is also accumulated on the data electrode Dk.

In this manner, the writing operation in the first discharge cells is completed. In addition, in the discharge cells to which the write pulse voltage Vd is not applied, write discharge does not occur.

Next, the scan pulse voltage Va is applied to the scan electrode SC2 in the second row, the write pulse voltage Vd is applied to the data electrode Dk corresponding to the discharge cell to emit light in the second row, and in the discharge cell in the second row, Write operation is performed.

The same write operation is performed by scan electrode SC3, scan electrode SC4,... In this order, scan electrodes SCn are sequentially executed up to the n-th discharge cell, and the writing period of the subfield SF1 ends.

In addition, although FIG. 4 shows the structure which applies voltage Ve1 to the sustain electrode SU1-the sustain electrode SUn in the latter part of an initialization period, and applies voltage Ve2 in a writing period, although this voltage Ve1 and the voltage Ve2 are mutually the same voltage value, it is shown. good.

In the subsequent sustain period of the subfield SF1, a voltage of 0 (V) is first applied to the sustain electrodes SU1 through SUn. Then, a sustain pulse of positive voltage Vs is applied to scan electrodes SC1 to SCn. Hereinafter, this voltage Vs is also referred to as "hold pulse voltage".

By the application of the sustain pulse voltage Vs, in the discharge cell in which the address discharge is generated, the voltage difference between the scan electrode SCi and the sustain electrode SUi exceeds the discharge start voltage and sustain discharge occurs. The phosphor layer 35 emits light by the ultraviolet rays generated by the discharge. In addition, due to this discharge, a negative wall voltage is accumulated on scan electrode SCi, and a positive wall voltage is accumulated on sustain electrode SUi. The positive wall voltage also accumulates on the data electrode Dk. However, sustain discharge does not occur in the discharge cells in which the address discharge has not occurred in the address period.

Next, voltage 0 (V) is applied to scan electrodes SC1 through SCn, and sustain pulse voltage Vs is applied to sustain electrodes SU1 through SUn. In the discharge cell in which the sustain discharge was generated immediately before, sustain discharge is generated again, negative wall voltage is accumulated on sustain electrode SUi, and positive wall voltage is accumulated on scan electrode SCi.

Thereafter, similarly, sustain pulses of a number obtained by multiplying the luminance weight by a predetermined brightness multiple are alternately applied to scan electrodes SC1 to SCn and sustain electrodes SU1 to sustain electrode SUn. In this way, the discharge cells which generate the write discharge in the write period emit light with luminance according to the luminance weight.

After the generation of the sustain pulse in the sustain period, voltage 0 (V) is applied to scan electrodes SC1 through SCn with voltage 0 (V) applied to sustain electrodes SU1 through SUn and data electrodes D1 through Dm. A ramp waveform voltage (lamp voltage) that rises gently from V) toward the voltage Vr is applied.

While this lamp voltage is applied to scan electrodes SC1 to SCn, weak discharge occurs in the discharge cells in which sustain discharge is generated. The charged particles generated by this weak discharge accumulate and accumulate on the sustain electrode SUi and the scan electrode SCi so as to alleviate the voltage difference between the sustain electrode SUi and the scan electrode SCi. This weakens the wall voltages on scan electrode SCi and sustain electrode SUi while leaving the positive wall voltage on data electrode Dk. That is, unnecessary wall charges in the discharge cell are erased.

When the voltage applied to scan electrode SC1-scan electrode SCn reaches the voltage Vr, the voltage applied to scan electrode SC1-scan electrode SCn will fall to voltage 0 (V). In this way, the holding | maintenance operation | movement in the holding period of subfield SF1 is complete | finished.

By the above, the subfield SF1 is complete | finished.

Next, the subfield SF2 which is the selection initialization subfield will be described.

In the initialization period of the subfield SF2, voltage Ve1 is applied to sustain electrode SU1 through sustain electrode SUn, and voltage 0 (V) is applied to data electrode D1 through data electrode Dm. The inclination waveform voltage (lamp voltage) which falls gently from the voltage which becomes less than discharge start voltage (for example, voltage 0 (V)) toward negative voltage Vi4 is applied to scan electrode SC1-the scanning electrode SCn. The voltage Vi4 is set to a voltage that exceeds the discharge start voltage with respect to the sustain electrode SU1 to the sustain electrode SUn.

While this ramp voltage is applied to scan electrodes SC1 to SCn, weak initialization discharge occurs in the discharge cells in which sustain discharge is generated in the sustain period of the immediately preceding subfield (subfield SF1 in FIG. 4). By this initialization discharge, the wall voltage on scan electrode SCi and sustain electrode SUi is weakened. The excess portion of the wall voltage accumulated on the data electrode Dk is discharged, and the wall voltage on the data electrode Dk is adjusted to a wall voltage suitable for the write operation.

On the other hand, in the discharge cells in which sustain discharge has not been generated in the sustain period of the immediately preceding subfield (subfield SF1), the initializing discharge does not occur, and the previous wall voltage is maintained.

In this manner, the initialization operation in the subfield SF2 is a selective initialization operation for selectively generating initialization discharge in the discharge cells which performed the writing operation in the writing period of the immediately preceding subfield.

By the above, the selection initialization operation | movement in the initialization period of subfield SF2 is complete | finished.

In the writing period of the subfield SF2, the same driving voltage waveform as the writing period of the subfield SF1 is applied to each electrode, and a writing operation of accumulating wall voltage on each electrode of the discharge cell to emit light is performed.

In the subsequent sustain period, similarly to the sustain period of the subfield SF1, the number of sustain pulses according to the luminance weight is alternately applied to the scan electrodes SC1 to the scan electrodes SCn and the sustain electrodes SU1 to the sustain electrodes SUn, and the address discharge is performed in the address period. Sustained discharge is generated in the discharge cells which generate.

In the initialization period and the writing period of each subfield after the subfield SF3, the same drive voltage waveform as the initialization period and the writing period of the subfield SF2 is applied to each electrode. In the sustain period of each subfield after the subfield SF3, the same drive voltage waveform as the subfield SF2 is applied to each electrode except for the number of sustain pulses generated in the sustain period.

The above is the outline | summary of the drive voltage waveform applied to each electrode of the panel 10 in this embodiment.

Next, a method of displaying gradation on the panel 10 will be described.

In the present embodiment, as described above, one field is composed of a plurality of subfields in which the luminance weight is set in advance. By selectively emitting the subfields according to the magnitude of the gradation values displayed on the discharge cells, each discharge cell is made to emit light at the brightness according to the gradation values, and an image is displayed on the panel 10. Hereinafter, the subfields to emit light are also referred to as "lighting subfields" and non-lighting subfields as "nonlighting subfields".

There are a plurality of combinations of the lit subfield and the non-lit subfield in one field. Hereinafter, the combination of the lighting subfield and the non-lighting subfield in one field is called "coding". In the present embodiment, a plurality of codings (display codings) used for displaying gray scales are selected from among the plurality of codings, and a combination set for display is created. Hereinafter, the combination set for display is called "coding table."

Then, the light emission and non-emission of each subfield are controlled based on the coding belonging to the coding table, the discharge cells are emitted at luminance corresponding to the magnitude of the gradation value, and an image is displayed on the panel 10.

Next, the coding table used in this embodiment is demonstrated.

In the following description, the gradation value (gradation value when no sustain discharge is generated) when displaying black is set to "0". In addition, the gradation value corresponding to the luminance weight "N" is described as gradation value "N".

Therefore, for example, the gradation value displayed by the discharge cells emitting only the subfield SF1 having the luminance weight "1" becomes the gradation value "1". In addition, the gradation value displayed by the discharge cell in which only the subfield SF1 of the luminance weight "1" and the subfield SF2 of the luminance weight "2" emits light is 1 + 2 = 3, resulting in the gradation value "3".

The plasma display device according to the present embodiment includes a plurality of coding tables in which the number of codings is different. That is, the plasma display device according to the present embodiment includes a plurality of coding tables in which the number of gray levels that can be displayed on the panel 10 is different.

5A is a diagram illustrating an example of a first coding table used for the plasma display device according to the first embodiment of the present invention.

5B is a diagram illustrating an example of a second coding table used for the plasma display device according to the first embodiment of the present invention.

The first coding table is the "first display combination set", and the second coding table is the "second display combination set".

In addition, in the coding table shown to FIG. 5A and FIG. 5B, the numerical value written directly below the notation which shows each subfield represents the brightness weight of each subfield. In the coding tables shown in Figs. 5A and 5B, each subfield of subfield SF1 to subfield SF6 has a luminance weight of "1", "2", "4", "8", "16", and "32", respectively. Has

In the coding tables shown in Figs. 5A and 5B, the subfields to emit light are represented by " ○ " and the non-emission subfields are indicated by blanks, and the leftmost column shows values of gray scales displayed in each coding.

For example, based on the coding table shown in FIG. 5A, the subfield SF1 and the subfield SF2 emit light in the discharge cells displaying the gray scale value "3". Alternatively, in the discharge cell displaying the gradation value "23", the subfield SF1, the subfield SF2, the subfield SF3, and the subfield SF5 emit light.

The first coding table shown in FIG. 5A is a set of codings having a rule that "the subfield SF1 always emits light in the discharge cells displaying the gradation value" 1 "or more." This rule can be said as "the discharge cell which does not emit light in the subfield SF1 does not emit light even after the subfield SF2." In addition, this rule can be said as "the subfield SF1 also necessarily emits light in the discharge cell which subfield SF2 emits light."

That is, the first coding table combines the light-emitting subfield and the non-light-emitting subfield so that the subfield after the specific subfield does not emit light unless the specific subfield emits light, and the specific coding in the first coding table is performed. The subfield is subfield SF1.

Therefore, in the first coding table shown in Fig. 5A, the subfield SF1 always emits light in the discharge cell displaying the gradation value "1" or more. According to this rule, as shown in Fig. 5A, 33 gray levels can be displayed in six subfields from subfield SF1 to subfield SF6.

In the second coding table shown in FIG. 5B, the subfield SF1 always emits light in the discharge cells displaying the "gradation value" 1 "or more, and the subfield SF2 always emits light in the discharge cell displaying the tone value" 3 "or more. , Subfield SF3 always emits light in a discharge cell displaying a gradation value of "7" or more. This rule states that "discharge cells that do not emit light in subfield SF1 do not emit light even after subfield SF2, and discharge cells that do not emit light in subfield SF2 do not emit light after subfield SF3 and do not emit light in subfield SF3. Does not emit light even after the subfield SF4 ”. In addition, this rule can be said as "the subfield SF1 and the subfield SF2 and the subfield SF3 always emit light in the discharge cell which subfield SF4 emits light."

In other words, the second coding table combines the light-emitting subfield and the non-light-emitting subfield so that the subfield after the specific subfield does not emit light unless the specific subfield emits light. The subfields are subfield SF1, subfield SF, and subfield SF3. Therefore, the number of specific subfields in the second coding table is larger than the number of specific subfields in the first coding table.

In the second coding table shown in FIG. 5B, the subfield SF1, the subfield SF2, and the subfield SF3 always emit light in the discharge cells displaying the tone value "7" or more. According to this rule, as shown in Fig. 5B, eleven gradation values can be displayed in six subfields from subfield SF1 to subfield SF6.

In the first coding table shown in FIG. 5A, out of the 33 gray scale values that can be displayed on the panel 10, 26 gray scale values in which non-emission subfields are generated between the light emitting subfield and the light emitting subfield are generated. to be. On the other hand, in the second coding table shown in FIG. 5B, among the eleven gray scale values that can be displayed on the panel 10, four gray scale values in which non-emission subfields are generated between the light emitting subfield and the light emitting subfield are displayed. to be.

Therefore, when the gray scale is displayed on the panel 10 by using the second coding table, the probability that the light emitting subfields occur continuously is higher than when the gray scale is displayed on the panel 10 by using the first coding table. . Therefore, when the gray scale is displayed on the panel 10 using the second coding table, the writing operation can be performed more stably.

In addition, the rule in each of the 1st coding table and the 2nd coding table changes to "The discharge cell which does not emit light in a specific subfield does not emit light also in the subfield after a specific subfield in 1 field." I can speak. Subfields specified in the first coding table are subfield SF1, and subfields specified in the second coding table are subfield SF1, subfield SF2, and subfield SF3.

Therefore, the number of gradation values that can be displayed on the panel 10 is smaller than that of the first coding table in which the number of the specific subfields is small.

In addition, when displaying an image on the panel 10 based on the first coding table shown in Fig. 5A, even-numbered gradation values such as gradation value "2", gradation value "4", gradation value "6" are used. Can't. In addition, when displaying an image on the panel 10 based on the 2nd coding table shown in FIG. 5B, gradation value "2", gradation value "4", gradation value "5", gradation value "6", gradation value Gradation values such as "8", "9", and "10" cannot be used. However, these gradation values can be displayed on the panel 10 in a pseudo manner using techniques known in general such as dither processing and error diffusion processing.

In the present embodiment, the image signal is converted into image data while switching between the first coding table shown in FIG. 5A and the second coding table shown in FIG. 5B based on the image signal.

6 is a diagram schematically showing an example of a circuit block constituting the plasma display device 40 according to the first embodiment of the present invention.

The plasma display device 40 shown in the present embodiment includes a panel 10 and a drive circuit for driving the panel 10. The driving circuit supplies power required for the image signal processing circuit 41, the data electrode driving circuit 42, the scan electrode driving circuit 43, the sustain electrode driving circuit 44, the timing generating circuit 45, and each circuit block. A power supply circuit (not shown) to be provided is provided.

The red image signal, the green image signal, and the blue image signal are input to the image signal processing circuit 41. The image signal processing circuit 41 assigns a gradation value to each discharge cell based on the input image signal, and the gradation value is image data indicating light emission / non-emission for each subfield (light emission / ratio). Light emission is converted into data corresponding to "1" and "0" of the digital signal. At this time, the image signal processing circuit 41 generates image data based on the first coding table or the second coding table described above.

That is, the image signal processing circuit 41 converts the red image signal, the green image signal, and the blue image signal into red image data, green image data, and the like based on the first coding table or the second coding table. The image data is converted into blue image data and output. For example, the image signal processing circuit 41 outputs image data "110000" when displaying the gradation value "3", and outputs image data "111010" when displaying the gradation value "23".

The image data is assumed to be arranged in order of subfield SF1, subfield SF2, subfield SF3, subfield SF4, subfield SF5, and subfield SF6.

The timing generating circuit 45 generates various timing signals for controlling the operation of each circuit block based on the horizontal synchronizing signal and the vertical synchronizing signal. Then, the generated timing signal is supplied to each circuit block (data electrode driving circuit 42, scan electrode driving circuit 43, sustain electrode driving circuit 44, image signal processing circuit 41, and the like).

The data electrode driving circuit 42 corresponds to each data electrode D1 to data electrode Dm based on the image data of each color output from the image signal processing circuit 41 and the timing signal supplied from the timing generating circuit 45. A write pulse is generated. The data electrode driving circuit 42 applies the write pulse to each of the data electrodes D1 to Dm in the writing period.

The scan electrode driving circuit 43 includes an initialization waveform generating circuit, a sustain pulse generating circuit, and a scanning pulse generating circuit (not shown in FIG. 6), and is driven based on a timing signal supplied from the timing generating circuit 45. A waveform is created and applied to each of scan electrode SC1-scan electrode SCn. The initialization waveform generating circuit generates an initialization waveform applied to the scan electrodes SC1 to the scan electrodes SCn in the initialization period based on the timing signal. The sustain pulse generating circuit generates a sustain pulse applied to the scan electrodes SC1 to the scan electrodes SCn in the sustain period based on the timing signal. The scan pulse generation circuit includes a plurality of scan electrode drive ICs (scan ICs), and generates scan pulses applied to scan electrodes SC1 to SCn SCn in the writing period based on the timing signal.

The sustain electrode driving circuit 44 includes a sustain pulse generating circuit and a circuit for generating the voltage Ve1 and the voltage Ve2 (not shown in FIG. 6), and is driven based on a timing signal supplied from the timing generating circuit 45. A voltage waveform is created and applied to each of sustain electrode SU1-the sustain electrode SUn. In the sustain period, a sustain pulse is generated based on the timing signal, and is applied to sustain electrodes SU1 through SUn.

FIG. 7 is a diagram schematically showing an example of the configuration of an image signal processing circuit 41 used in the plasma display device 40 according to Embodiment 1 of the present invention. In addition, in FIG. 7, only the circuit block which concerns on each operation | movement shown in this embodiment is shown, and the other circuit block is abbreviate | omitted.

Hereinafter, the coding table is simply referred to as "table", the first coding table is referred to as "first table", and the second coding table as "second table".

The image signal processing circuit 41 stores a storage device (hereinafter referred to as "first table 52R") that stores a first table corresponding to a red image signal, and a first table corresponding to a green image signal. Storage device (hereinafter referred to as "first table 52G") and a first device corresponding to blue image signal (hereinafter referred to as "first table 52B") And a storage device (hereinafter referred to as "second table 53B") that stores a second table corresponding to a blue image signal, a data conversion unit 54R corresponding to a red image signal, and green A data converter 54G corresponding to an image signal, a data converter 54B corresponding to a blue image signal, a table determination unit 55, and a selector 56B are provided.

Each storage device that stores a table can arbitrarily read data of each coding stored therein according to the gradation value.

Although not shown in FIG. 7, the image signal processing circuit 41 corresponds to a gradation value converter corresponding to a red image signal, a gradation value converter corresponding to a green image signal, and a blue image signal. And a gradation value converting unit.

The gradation value converting section corresponding to the red image signal is required signal processing for displaying the image corresponding to the red image signal on the panel 10, for example, pixel number conversion or gamma correction according to the number of pixels of the panel 10, and the like. Signal processing is performed on the red image signal. Then, the red image signal subjected to the signal processing is converted into the red gradation value.

As described above, the gradation value converting unit corresponding to the green image signal performs necessary signal processing on the green image signal and converts it into the green gradation value. As described above, the gradation value converting section corresponding to the blue image signal performs necessary signal processing on the blue image signal and converts it to the blue gradation value.

The gradation value converting section corresponding to the red image signal, the gradation value converting section corresponding to the green image signal, and the gradation value converting section corresponding to the blue image signal are composed of the red gradation values and the green constituting one pixel. It operates in synchronization with each other so that the gradation value and the gradation value of blue are simultaneously output.

The data conversion unit 54R reads coding data from the first table 52R based on the red gradation value output from the gradation value conversion unit corresponding to the red image signal. Then, the read data is output as red image data.

The data conversion unit 54G reads coding data from the first table 52G based on the green gradation value output from the gradation value conversion unit corresponding to the green image signal. The read data is output as green image data.

The table determining unit 55 includes a comparator 61, a comparator 62, and an OR gate 63.

The comparator 61 compares the red gradation value output from the gradation value conversion section corresponding to the red image signal with a predetermined threshold value. In this embodiment, the predetermined threshold is set to "3", for example. The comparator 61 outputs a "H" level when the red gradation value is greater than or equal to the predetermined threshold (e.g., the red gradation value is greater than or equal to "3"), and the red gradation value is less than the predetermined threshold (for example, If the red gradation value is less than "3", the "L" level is output.

The comparator 62 compares the green gradation value output from the gradation value conversion section corresponding to the green image signal with a predetermined threshold value. In the present embodiment, the predetermined threshold is set to, for example, "3" as described above. The comparator 62 outputs a "H" level when the green gradation value is greater than or equal to the predetermined threshold (for example, the green gradation value is greater than or equal to "3"), and the green gradation value is less than the predetermined threshold (for example, If the green gradation value is less than "3", the "L" level is output.

The OR gate 63 performs an OR operation on the output of the comparator 61 and the output of the comparator 62, and outputs the result. That is, the OR gate 63 outputs the "L" level when the output of the comparator 61 and the output of the comparator 62 are both "L" level, and otherwise outputs the "H" level.

Therefore, in the present embodiment, the OR gate 63 adjusts the "H" level if at least one of the red and green gradation values is equal to or greater than a predetermined threshold (for example, gradation value "3" or more). Output Then, the output of the OR gate 63 is input to the selector 56B as the output of the table determining unit 55.

The selector 56B selects either the first table 52B or the second table 53B based on the signal output from the table determining unit 55. The selector 56B in the present embodiment selects the second table 53B when the output of the table determining unit 55 is at the "H" level, and the output of the table determining unit 55 is at the "L" level. If so, the first table 52B is selected.

The data conversion unit 54B reads coding data from the table selected by the selector 56B based on the blue gradation value output from the gradation value conversion unit corresponding to the blue image signal. For example, when the first table 52B is selected in the selector 56B, the coding data is read out from the first table 52B based on the blue gradation value output from the gradation value converter. If the second table 53B is selected in the selector 56B, the coding data is read from the second table 53B based on the blue gradation value output from the gradation value converter. The read data is output as blue image data.

Therefore, in the present embodiment, the data conversion unit 54B, if at least one of the red gradation value and the green gradation value is equal to or greater than a predetermined threshold (for example, gradation value "3" or more), the data conversion unit 54B provides the second table. On the basis of this, blue tone values are converted into blue image data. Further, the data conversion unit 54B determines that the blue tone value is blue based on the first table when the red tone value and the green tone value together are less than a predetermined threshold (for example, less than the tone value "3"). Convert to image data.

Next, the reason why the image signal processing circuit 41 according to the present embodiment performs the above-described operation will be described.

8 is a diagram showing a minimum value of the write pulse voltage Vd required for the write operation in each subfield. In Fig. 8, the vertical axis represents the lowest value of the write pulse voltage Vd necessary for the stable write operation, and the horizontal axis represents the subfield. 8 shows the lowest value of the write pulse voltage Vd required for the write operation for each subfield in each of the red discharge cell, the green discharge cell, and the blue discharge cell.

When a crosstalk phenomenon in which charges move from one discharge cell to another discharge cell occurs, the wall charge in the discharge cell is reduced. Therefore, in the discharge cell, the minimum value of the write pulse voltage Vd required for writing rises. Therefore, crosstalk can be quantified by measuring the minimum voltage value of the write pulse voltage Vd necessary for the write operation.

The graph shown in FIG. 8 puts together the result measured as follows. First, among the three discharge cells constituting one pixel, one discharge cell (notice discharge cell) of interest in a specific subfield is not emitted, and the other two discharge cells are emitted. Next, the minimum value of the write pulse voltage required for writing the discharge cell of interest in the next subfield is measured.

Therefore, in FIG. 8, the measurement result after subfield SF2 is shown. In addition, the graph shown in FIG. 8 shows the characteristic of the crosstalk in each discharge cell of red, green, and blue of the panel 10. As shown in FIG.

In addition, the characteristic shown by AA in FIG. 8 showed the measurement result when the discharge cell of interest is made into the blue discharge cell, and the characteristic shown by BB in FIG. 8 is the case where the discharge cell of interest is made into the red discharge cell. The measurement result is shown, and the characteristic shown by CC in FIG. 8 shows the measurement result at the time of making discharge cell of interest into a green discharge cell.

In the measurement result shown in FIG. 8, in the panel 10, the minimum value of the write pulse voltage Vd in a blue discharge cell is higher than a red discharge cell and a green discharge cell. From this result, the wall charges in the blue discharge cells tend to decrease more than other discharge cells, and it is considered that the crosstalk in the blue discharge cells is more generated than the crosstalk in the other discharge cells.

This may be considered to be the cause of the following.

As shown in FIG. 3, in the panel 10 according to the present embodiment, the electrode widths of the data electrodes 32 constituting the red discharge cells and the green discharge cells are relatively wide, and blue discharge cells are formed. The electrode width of the constituent data electrodes 32 is relatively narrow.

When the electrode width of the data electrode 32 is widened, the write discharge can be generated more stably. However, on the other hand, the influence (for example, the influence on wall charge, etc.) which the generated write discharge has on the adjacent discharge cells becomes relatively large.

When the electrode width of the data electrode 32 is narrowed, compared with the discharge cells in which the electrode width of the data electrode 32 is widened, the write discharge tends to be unstable. On the other hand, however, the influence of the generated write discharge on the adjacent discharge cells becomes relatively small.

Therefore, in the red discharge cells and the green discharge cells of which the electrode width of the data electrode 32 is relatively wide, the write discharge can be generated more stably, and the minimum value of the write pulse voltage Vd required for the write operation is also relatively low. can do.

On the other hand, in the blue discharge cells in which the electrode width of the data electrode 32 is relatively narrow, the write discharge tends to be unstable as compared with the red discharge cells and the green discharge cells. Therefore, the minimum value of the write pulse voltage Vd required for the write operation becomes relatively high.

Moreover, the influence which the write discharge which generate | occur | produces in a blue discharge cell on the adjacent red discharge cell and green discharge cell is relatively small. That is, in the red discharge cells and the green discharge cells, the amount of crosstalk generated due to the address discharge generated in the blue discharge cells is relatively small. This also causes one of relatively low minimum values of the write pulse voltage Vd required for the write operation in the red discharge cells and the green discharge cells.

On the contrary, the influence of the write discharges generated in the red discharge cells and the green discharge cells on the adjacent blue discharge cells is relatively large. That is, in the blue discharge cell, the amount of crosstalk caused by the address discharge generated in the red discharge cell and the green discharge cell is relatively large. This is one factor of relatively high minimum value of the write pulse voltage Vd required for the write operation in the blue discharge cell.

In addition, compared to the panel in which the electrode widths of the data electrodes 32 of all the discharge cells are set equally wide, the data electrodes of one color discharge cell (blue discharge cell) among the three color discharge cells constituting one pixel. It was confirmed by the inventor that the panel which narrowed the electrode width of (32) compared with another discharge cell can suppress the generation amount of crosstalk. This is the reason why in the panel 10 according to the present embodiment, the electrode width of the data electrode 32 of the blue discharge cell is narrowed compared with other discharge cells.

As described above, in the present embodiment, the second table is used when converting the gradation value of the color of the discharge cell in which the electrode width of the data electrode 32 is narrowed in comparison with other discharge cells. . The second table has less gray scales that can be displayed on the panel 10 compared to the first table, and noise is likely to occur when the image signal is subjected to dither processing. And the human visual characteristic has confirmed that a blue image is harder to perceive a noise than a red image and a green image. This is the reason why in this embodiment, the discharge cell which narrows the electrode width of the data electrode 32 is made into the blue discharge cell.

As shown in FIG. 8, the blue discharge cell has a higher minimum value of the write pulse voltage Vd required for the write operation in the subfield SF2 and the subfield SF3 than other subfields. From this, it can be said that in the blue discharge cells, crosstalk is more likely to occur in the subfield SF2 and the subfield SF3 than in the other subfields.

When the blue discharge cells do not emit light and the discharge cells of different colors emit light in the subfield SF2 or the subfield SF3 among the three discharge cells constituting one pixel, they are blue in the subsequent subfields. This indicates that the write operation in the discharge cells of? Becomes unstable, and that sustain discharge may not occur.

An example of such a light emission pattern is shown to FIG. 9A and FIG. 9B.

FIG. 9A is a diagram showing an example of a light emission pattern in which the writing operation in the blue discharge cell is likely to become unstable in the plasma display device 40 according to Embodiment 1 of the present invention.

FIG. 9B is a diagram illustrating another example of the light emission pattern in which the writing operation in the blue discharge cell is unstable in the plasma display device 40 according to the first embodiment of the present invention.

In addition, in FIG. 9A and FIG. 9B, the subfield which emits light is shown as "(circle)" and the non-light emitting subfield is shown by the space.

For example, when the gradation value "27" is displayed in the red discharge cell, the gradation value "15" is displayed in the green discharge cell, and the gradation value "29" is displayed in the blue discharge cell, Consider an example of converting a gradation value into image data using one table.

In this case, as shown in FIG. 9A, in the subfield SF2, the red discharge cells and the green discharge cells emit light, and the blue discharge cells do not emit light. Therefore, for the reason described above, in the blue discharge cell, the write operation tends to be unstable in the subfield after the subfield SF3, and there is a possibility that sustain discharge does not occur. For example, when sustain discharge does not occur in all the subfields after the subfield SF3 in the blue discharge cell, the gradation value actually displayed in the blue discharge cell which should display the gradation value "29" becomes "1".

Alternatively, when the gradation value "31" is displayed in the red discharge cell, the gradation value "55" is displayed in the green discharge cell, and the gradation value "27" is displayed in the blue discharge cell, Consider an example of converting a gradation value into image data using one table.

In this case, as shown in FIG. 9B, in the subfield SF3, the red discharge cells and the green discharge cells emit light, and the blue discharge cells do not emit light. Therefore, for the reason described above, in the blue discharge cell, the write operation tends to be unstable in the subfield after the subfield SF4, and sustain discharge may not occur. For example, when sustain discharge does not occur in all the subfields after the subfield SF4 in the blue discharge cell, the gradation value actually displayed in the blue discharge cell which should display the gradation value "27" becomes "3".

In the blue discharge cell, in order to reduce crosstalk and perform the writing operation stably, a subfield in which the blue discharge cell does not emit light and at least one of the red discharge cell and the green discharge cell emits light is generated. Further, the image data may be created so that the light emitting pattern in which the blue discharge cells emit light in the subfield after the subfield does not occur. In particular, in the subfield SF2 and the subfield SF3 where crosstalk is relatively likely to occur in the blue discharge cell, it is preferable that such a light emission pattern is not generated.

Therefore, in the plasma display device 40 of the present embodiment, if at least one of the red and green gradation values is greater than or equal to the predetermined threshold (for example, gradation value " 3 " or more), the second table is used. On the basis of this, blue tone values are converted into blue image data.

At least one of the subfield SF2 and the subfield SF3 emits light, and the second table does not include coding that any one of the subfield SF4, the subfield SF5, and the subfield SF6 emits light. That is, in the image data based on the second table, the subfield SF1 emits light with all the gradation values equal to or greater than gradation value "1", the subfield SF2 emits light with all the gradation values equal to or greater than gradation value "3", and the gradation value "7". The subfield SF3 emits light with all the above gradation values.

Therefore, according to the operation described above, "in the subfield SF2 and the subfield SF3, the blue discharge cells do not emit light, at least one of the red discharge cells and the green discharge cells emit light, and the subsequent subfields. It is possible to prevent the plasma display device 40 from generating a light emitting pattern of “the blue discharge cell emits light”.

This makes it possible to reduce the crosstalk and perform the writing operation stably in the blue discharge cell in which crosstalk is relatively likely to occur.

In addition, when image data is created using the second table, the number of gradation values that can be displayed on the panel 10 is relatively small, but the gradation values that cannot be displayed are generally known as described above. The panel 10 can be displayed on the panel 10 using a technique such as dither processing or error diffusion processing.

In the present embodiment, when the blue discharge cell is a light emitting pattern in which crosstalk is hard to occur, that is, the red and green gradation values together are less than a predetermined threshold (for example, less than gradation value "3"). ), Blue tone values are converted into blue image data based on the first table.

As a result, the number of gray scale values that can be displayed in the blue discharge cells can be relatively increased in comparison with the configuration in which the blue gray values are always converted to blue image data based on the second table. Therefore, when crosstalk is difficult to occur in the blue discharge cells, the number of gray scale values that can be displayed in the blue discharge cells can be relatively increased, and the image display quality in the plasma display device 40 can be improved. .

As described above, in the present embodiment, "first color" and "second color" are set based on the electrode width of the data electrode 32. That is, the color of the discharge cells having a relatively large electrode width of the data electrode 32 is set as the "first color", and the color of the discharge cells of which the electrode width of the data electrode 32 is relatively narrow is set to "first color". Two colors.

For the discharge cells of the "second color", the gradation values are converted into image data based on either of the first table and the second table, and the light emission of each subfield is based on the image data. Control non-luminescence. Regarding the discharge cells of the "first color", the gradation value is converted into image data based on the first table, and light emission and non-emission of each subfield are controlled based on the image data.

At this time, if at least one of the gradation values of the "first color" is equal to or greater than the predetermined threshold value, the gradation value of the "second color" is converted into image data based on the second table, and the gradation value of the "first color" Together, if less than the predetermined threshold value, the gradation value of the "second color" is converted into image data based on the first table.

For example, when the "second color" is blue, when converting the blue gradation value into image data, the "other colors" are red and green which are "first colors". If at least one of the red and green gradation values is greater than or equal to the predetermined threshold value, the blue gradation value is converted into blue image data based on the second table, and the red and green gradation values are Together, if less than the predetermined threshold value, the blue tone value is converted into blue image data based on the first table.

When the gray level is displayed on the panel 10 using the second table, the probability that the light emitting subfields occur continuously is higher than when the gray level is displayed on the panel 10 using the first table. Set up the second table.

As a result, in the discharge cells of a color in which the electrode width of the data electrode 32 is relatively narrow and relatively crosstalk is likely to occur, it is possible to prevent the occurrence of crosstalk and to display a high quality image on the panel 10. It becomes possible.

In the present embodiment, the electrode widths of the data electrodes 32 constituting the red discharge cells and the green discharge cells are relatively wide, and the electrode widths of the data electrodes 32 constituting the blue discharge cells are relative. For example, each operation was explained by setting the "first color" to red and green and the "second color" to blue, taking the narrow panel 10 as an example. However, the present invention is not limited to this structure at all. For example, when the electrode widths of the data electrodes 32 constituting the blue discharge cells and the green discharge cells are relatively wide, and the electrode widths of the data electrodes 32 constituting the red discharge cells are relatively narrow, What is necessary is just to set "1 color" to blue and green, and to set "2nd color" to red. Alternatively, when the electrode widths of the data electrodes 32 constituting the red discharge cells and the blue discharge cells are relatively wide, and the electrode widths of the data electrodes 32 constituting the green discharge cells are relatively small, the " 1 color "may be set to red and blue, and" 2nd color "may be set to green.

In addition, in this embodiment, although the structure which makes a predetermined threshold value "3" was demonstrated, this invention is not limited to this structure at all. Preferably, the predetermined threshold is optimally set in accordance with each coding constituting the first table and the second table.

In the present embodiment, an example in which the above-described operation is performed in the image signal processing circuit 41 using three discharge cells constituting one pixel as one unit is described. However, the present invention is not limited to this structure at all. For example, a delay circuit is provided between the comparator 61 and the OR gate 63, or between the comparator 62 and the OR gate 63, so that three discharge cells adjacent to each other across the pixel are arranged in one unit. In this case, the above configuration may be performed. For example, the operation example shown in this embodiment is effective when one pixel is composed of three discharge cells arranged in the order of green, blue, and red. However, for example, when one pixel is formed of three discharge cells arranged in the order of "first color" is red and green, "second color" is blue, and red, green, and blue, the pixels are spread over the pixels. It is preferable to provide a delay circuit appropriately so that the calculation of the table determination unit 55 is performed by using three discharge cells of adjacent green, blue and red colors as one unit.

Moreover, in this embodiment, the structure which provides two tables, a 1st table and a 2nd table, and selects any one table based on the determination result in the table determination part 55 was demonstrated. However, the present invention is not limited to this structure at all. For example, in addition to the 1st table and the 2nd table, the structure which provides a 3rd table may be sufficient. Or the structure which provides more tables, such as a 4th table and a 5th table, may be sufficient.

The specific example at the time of providing a 3rd table is demonstrated. For example, the third table has a rule that "the discharge cells which do not emit light in the subfield SF1 do not emit light even after the subfield SF2, and the discharge cells which do not emit light in the subfield SF2 do not emit light even after the subfield SF3." Shall be. When the gradation value of the "second color" is converted into image data, if the gradation value of the "first color" is also less than the predetermined threshold value, the gradation value of the "second color" is imaged based on the first table. Convert to data. In addition, if any of the gradation values of the "first color" is equal to or greater than the predetermined threshold value, the gradation value of the "second color" is converted into image data based on the third table. And when the gradation value of a "first color" is more than a predetermined threshold, the gradation value of a "second color" is converted into image data based on a 2nd table. For example, such a structure may be sufficient.

Or, for example, when the "second color" is made blue, if the red or green gradation value is less than the first threshold value (for example, "3"), the first table is used and the red gradation value or green color is used. If the gradation value of is greater than or equal to the first threshold and is less than the second threshold (for example, "7"), the third table is used. The configuration may be used to convert a blue gradation value into image data.

In addition, according to this rule, it is also possible to provide more tables and to increase the number of subfields to be prevented from crosstalk in the discharge cells of the "second color".

In addition, this rule means that when the discharge cells emitting the "first color" emit light to at least the subfield SF (N) by the image data based on the gradation value of the "first color", In the discharge cells emitting two colors, the image data corresponding to the gray scale value of the "second color" so that the subfield after the subfield SF (N + 1) does not emit light unless the light is emitted from the subfield SF (N). To generate an error. "

For example, when the discharge cell which emits a "first color" is light-emitting to at least subfield SF4 by image data based on the gradation value of a "first color", the discharge cell which emits a "second color" In this case, the image data corresponding to the gradation value of the "second color" is generated so that the subfield after the subfield SF5 does not emit light unless it emits light in the subfield SF4.

Or when the discharge cell which emits a "1st color" by the image data based on the gradation value of "the 1st color" is emitting to at least subfield SF5, the discharge cell which emits a "2nd color" In this case, the image data corresponding to the gradation value of the "second color" is generated so that the subfield after the subfield SF6 does not emit light unless it emits light in the subfield SF5.

In the present invention, it is also possible to operate the plasma display apparatus in this manner by increasing the number of tables.

In addition, in the present embodiment, the second table is set as shown in FIG. 5B for the purpose of reducing the crosstalk generated in the subfield SF2 and the subfield SF3 based on the measurement result shown in FIG. 8. . However, the present invention is not limited to this structure at all. It is preferable to set the 2nd table optimally according to the subfield used as the object to reduce crosstalk.

For example, in the case of reducing the crosstalk generated in the subfield SF2, the subfield SF3, and the subfield SF4, the "discharge cells not emitting light in the subfield SF1 do not emit light even after the subfield SF2, Discharge cells that do not emit light in SF2 do not emit light even after subfield SF3, discharge cells that do not emit light in subfield SF3 do not emit light after subfield SF4, and discharge cells that do not emit light in subfield SF4 do not emit light even after subfield SF5. The second table may be set based on the rule of "No".

(Embodiment 2)

In the first embodiment, among the three-color discharge cells constituting one pixel, the two-color discharge cells have a relatively wide electrode width of the data electrode 32, and the one-color discharge cells of the data electrode 32 have the same width. An example in which the electrode width is relatively narrow has been described. That is, the panel 10 having a relatively wide electrode width of the data electrode 32 constituting the red discharge cell and the green discharge cell, and a relatively narrow electrode width of the data electrode 32 constituting the blue discharge cell. For example, each operation was described.

In the present embodiment, among the three-color discharge cells constituting one pixel, the discharge cells of one color have a relatively wide electrode width of the data electrode 32, and the two-color discharge cells of the discharge electrode of the data electrode 32. An example in which the electrode width is relatively narrow will be described.

Fig. 10 is a schematic diagram showing an enlarged arrangement of discharge cells and data electrodes of a panel used in the plasma display device according to the second embodiment of the present invention.

In the panel in this embodiment, the electrode width of the data electrode 32 which comprises a green discharge cell is comparatively wide, and the electrode width of the data electrode 32 which comprises a red discharge cell and a blue discharge cell. Is relatively narrow.

Therefore, in the present embodiment, the "second color" is red and blue.

11 is a diagram schematically showing an example of the configuration of an image signal processing circuit 141 used in the plasma display device according to the second embodiment of the present invention. 11, only the circuit block which concerns on each operation | movement shown in this embodiment is shown, and the other circuit block is abbreviate | omitted.

The image signal processing circuit 141 shown in FIG. 11 has a structure substantially the same as the image signal processing circuit 41 shown in FIG. 7. The point that the image signal processing circuit 141 shown in FIG. 11 differs from the image signal processing circuit 41 is that, in addition to the configuration of the image signal processing circuit 41, a memory storing a second table corresponding to a red image signal The device (hereinafter referred to as "second table 53R") and the selector 56R are different from the table determination unit 55 in that the configuration of the table determination unit 80 is different.

Hereinafter, the structure different from the image signal processing circuit 41 shown in FIG. 7 is demonstrated, and description is abbreviate | omitted about the same structure.

The second table stored in the second table 53R is the same as the second table shown in Fig. 5B. Therefore, the table stored in the second table 53R and the table stored in the second table 53B are the same.

The table determining unit 80 has a comparator 64 and an OR gate 65 in addition to the configuration of the table determining unit 55 shown in FIG. 7.

The comparator 64 compares the blue gradation value output from the gradation value conversion section corresponding to the blue image signal with a predetermined threshold value. In this embodiment, the predetermined threshold is set to "3", for example. The comparator 64 outputs a "H" level when the blue gradation value is greater than or equal to the predetermined threshold (e.g., the blue gradation value is greater than or equal to "3"), and the blue gradation value is less than the predetermined threshold (for example, If the blue tone value is less than "3", the "L" level is output.

The OR gate 65 performs an OR operation on the output of the comparator 62 and the output of the comparator 64, and outputs the result. That is, the OR gate 65 outputs the "L" level when the output of the comparator 62 and the output of the comparator 64 are both "L" levels, and outputs the "H" level other than that.

Therefore, in the present embodiment, the OR gate 65 adjusts the "H" level if at least one of the green and blue gradation values is equal to or greater than the predetermined threshold value (for example, gradation value "3" or more). Output The output of the OR gate 65 is input to the selector 56R.

The selector 56R selects either the first table 52R or the second table 53R based on the signal output from the OR gate 65 of the table determining unit 80. The selector 56R in the present embodiment selects the second table 53R when the output of the OR gate 65 is at the "H" level, and selects the second table 53R when the output of the OR gate 65 is at the "L" level. 1 Select the table 52R.

The data conversion unit 54R reads the coding data from the table selected by the selector 56R based on the red gradation value output from the gradation value conversion unit corresponding to the red image signal. For example, when the first table 52R is selected in the selector 56R, the coding data is read from the first table 52R based on the red gradation value output from the gradation value converting section. When the second table 53R is selected in the selector 56R, the coding data is read from the second table 53R based on the red gradation value output from the gradation value converting section. Then, the read data is output as red image data.

Therefore, in the present embodiment, the data conversion unit 54R, if at least one of the green gradation value and the blue gradation value is equal to or greater than a predetermined threshold (for example, gradation value "3" or more), adds to the second table. On the basis of this, the red tone value is converted into red image data. Further, the data conversion unit 54R determines that the red gradation value is red based on the first table if the green gradation value and the blue gradation value are both less than a predetermined threshold (for example, less than the gradation value "3"). Convert to image data.

As described above, in the example shown in this embodiment, among the three color discharge cells constituting one pixel, the electrode width of the data electrode 32 is relatively narrow in the two color discharge cells, and the discharge cell of one color is relatively small. The electrode width of the data electrode 32 is relatively wide. Therefore, unlike Embodiment 1, "the first color" is one color and "the second color" is two colors.

Then, for the "first color", the gradation value is converted into image data based on the first table, and for the "second color", based on either one of the first table and the second table. The tone value is converted into image data.

When converting the gradation value of the "second color" into image data, if at least one of the gradation values of the "second color" is equal to or greater than a predetermined threshold value, the gradation value is converted into the image data based on the second table, If the gradation value of " color " together is less than a predetermined threshold, the gradation value is converted into image data based on the first table.

At this time, for example, when the "second color" is red and blue, the "other color" at the time of converting the blue tone value into image data is red and green. In addition, "different colors" at the time of converting red tone values into image data are blue and green.

When converting the blue tone value into image data, if at least one of the red tone value and the green tone value is greater than or equal to the predetermined threshold value, the blue tone value is converted into the blue image data based on the second table. If the red and green gradation values together are less than the predetermined threshold, the blue gradation values are converted into blue image data based on the first table. When converting the red gradation value into image data, if at least one of the blue gradation value and the green gradation value is greater than or equal to a predetermined threshold value, the red gradation value is converted into red image data based on the second table. If the blue and green gradation values together are less than a predetermined threshold, the red gradation values are converted into red image data based on the first table.

As a result, in the discharge cells of a color in which the electrode width of the data electrode 32 is relatively narrow and relatively crosstalk is likely to occur, it is possible to prevent the occurrence of crosstalk and to display a high quality image on the panel 10. It becomes possible.

In addition, the drive voltage waveform shown in FIG. 4 only showed an example in embodiment of this invention, and this invention is not limited to these drive voltage waveforms at all. 6, 7, and 11 show only an example in the embodiment of the present invention, and the present invention is not limited to these circuit configurations at all.

In the embodiment of the present invention, an example in which one field is composed of six subfields has been described. However, the present invention is not limited to the above number at all by the number of subfields constituting one field. For example, by increasing the number of subfields, the number of gradations that can be displayed on the panel 10 can be further increased.

In addition, each circuit block shown in the embodiment of the present invention may be configured as an electric circuit that performs each operation shown in the embodiment, or may be configured using a microcomputer or the like programmed to perform the same operation. .

In addition, in the embodiment of the present invention, an example in which one pixel is composed of three colors of red, green, and blue discharge cells has been described. However, a panel in which one pixel is composed of four or more color discharge cells Also in this invention, it is possible to apply the structure shown to embodiment in this invention, and the same effect can be acquired.

In addition, the specific numerical value shown in embodiment of this invention was set based on the characteristic of the panel 10 whose screen size is 50 inches and the number of display electrode pairs 24 is 1024, and only in embodiment It only shows an example. This invention is not limited to these numerical values at all, It is preferable to set each numerical value optimally according to the characteristic of a panel, the specification of a plasma display apparatus, etc. In addition, these numerical values shall allow the variation in the range which can obtain the above-mentioned effect. In addition, the number of subfields constituting one field, the luminance weight of each subfield, etc. are not limited to the values shown in the embodiment of the present invention, and even if the subfield configuration is switched based on an image signal or the like. good.

(Industrial availability)

The present invention not only increases the effect of suppressing crosstalk, but also suppresses the influence of crosstalk on the image displayed on the panel when crosstalk occurs, and thus displays a high quality image on the panel. It is useful as a driving method of a display apparatus and a plasma display apparatus.

10: panel
21: front board
22: scanning electrode
23: sustain electrode
24: display electrode pair
25, 33: dielectric layer
26: protective layer
31: back substrate
32: data electrode
34: bulkhead
35, 35R, 35G, 35B: phosphor layer
40: plasma display device
41, 141: image signal processing circuit
42: data electrode driving circuit
43: scan electrode driving circuit
44: sustain electrode driving circuit
45: timing generating circuit
52R, 52G, 52B: the first table
53R, 53B: Second Table
54R, 54G, 54B: Data Converter
55, 80: table determination unit
56R, 56B: Selector
61, 62, 64: Comparator
63, 65: OR gate

Claims (6)

The display combination set includes a plurality of display combination sets comprising one field composed of a plurality of subfields with predetermined luminance weights and a plurality of combinations of light emitting subfields and non-light emitting subfields. Plasma for displaying gradations on a plasma display panel having a plurality of discharge cells having a data electrode having a width different from that of a display electrode pair consisting of a scan electrode and a sustain electrode, by controlling emission and non-emission of the discharge cells using a combination belonging to As a driving method of a display device,
The display combination set has a first display combination set and a second display combination set in which the number of combinations of the light emitting subfields and the non-light emitting subfields is smaller than the first display combination set,
When converting the gradation value of the discharge cell having a relatively large electrode width of the data electrode into image data, the first display combination set is used.
When converting the gradation value of the discharge cell of which the electrode width of the data electrode is relatively narrow into image data, the first display combination set or the second display combination set is used.
A driving method of a plasma display device, characterized in that.
The method of claim 1,
When converting the gradation value of the discharge cell of which the electrode width of the data electrode is relatively narrow into the image data, if the gradation value of at least one of the other discharge cells is equal to or more than a predetermined threshold value, the second display combination set is used. A method of driving a plasma display device.
The method of claim 1,
In the combination set for the first display and the combination set for the second display, a combination of a light emitting subfield and a non-light emitting subfield so that the subfield after the specific subfield does not emit light unless a specific subfield emits light. Select it,
The number of specific subfields in the second display combination set is larger than the number of specific subfields in the first display combination set.
A driving method of a plasma display device, characterized in that.
The method of claim 1,
And a light emitting color of the discharge cells having a relatively narrow electrode width of the data electrode is blue.
The method of claim 1,
And the colors emitted by the discharge cells of which the electrode widths of the data electrodes are relatively narrow are blue and red.
A plasma display panel including a plurality of discharge cells each having a display electrode pair consisting of a scan electrode and a sustain electrode and a data electrode having a different width;
One field is formed of a plurality of subfields having a writing period and a sustaining period in which a number of sustain pulses corresponding to luminance weights are applied to the display electrode pairs to drive the plasma display panel, and the subfields emitting light and the non-light-emitting A driving circuit comprising a plurality of display combination sets configured by selecting a plurality of combinations of subfields, and controlling the light emission and non-emission of discharge cells using a combination belonging to the display combination set to display gray scales.
A plasma display device comprising:
The drive circuit,
The plasma display panel using the display combination set having a first display combination set and a second display combination set in which the number of combinations of light emitting subfields and non-light emitting subfields is smaller than the first display combination set; In addition to displaying gradations in,
When converting the gradation value of the discharge cell having a relatively large electrode width of the data electrode into image data, the first display combination set is used.
When converting the gradation value of the discharge cell of which the electrode width of the data electrode is relatively narrow into image data, the first display combination set or the second display combination set is used.
Plasma display device, characterized in that.

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