JP2001236884A - Plasma display panel and its drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma display panel and its drive method capable of keeping a low discharge maintenance voltage and substantially improving the light-emitting efficiency, as compared with conventional ones. SOLUTION: The plasma display panel of an AC plane-discharge type is provided with a first electrode 12a and a second electrode 12b, covered with the dielectric layer 13 and formed in parallel with each other on the front glass base plate 11. A third electrode 22 is provided on a rear glass base plate 21, and a discharge space is produced by a partition board partitioning both base plates. The discharge gas is one of a mixture, containing a xenon of 5 vol.% or more and of less than 100 vol.% and set to the xenon partial pressure of 2 kPa or higher. Then, the clearance (maintenance discharge gap) between the pair-forming first electrode 12a and the second electrode 12b is designated at a larger height than that of the discharge space (opposed discharge gap).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC type plasma display panel used for a computer, a television and the like, and a method for driving the same.

[0002]

2. Description of the Related Art In recent years, in the field of displays, demands have been made for higher performance such as high definition display (such as high definition) and flattening, and various researches and developments have been made to meet the demand. Representative examples of flat displays include liquid crystal displays (LCDs) and plasma display panels (PDPs). Among them, PDPs are thin and suitable for large screens, and 50-inch class products have already been developed. Have been.

[0003] PDPs are roughly classified into a direct current type (DC type) and an alternating current type (AC type). At present, the AC type suitable for increasing the size is mainly used. FIG. 11A shows AC
FIG. 9 is a cross-sectional view of a main part showing a conventional example of a surface discharge type PDP. FIG. 11B is a sectional view taken along line AA of FIG. Generally, a PDP has a configuration in which light-emitting cells of each color are arranged in a matrix. An AC surface discharge type PDP is disclosed in, for example, JP-A-9-35628.
As shown in the figure, a front glass substrate 211 and a back glass substrate 221 are arranged in parallel via a partition 224,
Discharge electrode pairs (scanning electrodes 212a and sustaining electrodes 212b) are arranged in parallel on the front glass substrate 211, and a dielectric layer 213 and a protective layer 214 are formed so as to cover them. On the other hand, address electrodes 222 are arranged on the back glass substrate 221 at right angles to the scanning electrodes 212a, and in a space 230 partitioned by a partition between the two plates,
Each color phosphor layer 225 is provided, and a discharge gas (for example, neon and xenon) is sealed to form a panel structure in which each color light emitting cell is formed.

A voltage is applied to each electrode of the PDP by a drive circuit. Since each discharge cell can express only two gradations of light-on or light-off, red (R), green (G), blue (B)
For each color, a method is used in which one field is divided into a plurality of subfields, the lighting time is time-divided, and an intermediate gradation is expressed by a combination thereof (in-field time division gradation display method).

In each subfield, generally, ADS
(Address Display-period Separation), an image is displayed on the PDP. In this method, a setup period in which a pulse voltage is applied to the entire scan electrode for setup, and a pulse voltage is sequentially applied to the scan electrode, and a pulse voltage is applied to a selected electrode among the address electrodes to light up. A series of operations including an address period for accumulating wall charges in the cell and a discharge sustain period for sustaining discharge by applying a pulse voltage between the scan electrode and the sustain electrode are performed. Then, ultraviolet rays are emitted by the sustain discharge, and the phosphor particles (red, green, and blue) of the phosphor layer 225 receive the ultraviolet rays to excite and emit light, thereby displaying an image.

[0006]

In such a PDP, it has been a conventional problem to increase the luminous efficiency as much as possible while keeping the drive voltage as low as possible. Here, the reason why the drive voltage is kept as low as possible is that the circuit design becomes easy and the loss due to the reactive power can be reduced.

In consideration of this point, generally, the gas pressure of the PDP is set to about 40 to 65 kPa, and the ratio of xenon gas is set to about 5 vol%. Further, the gap dp between the scan electrode 212a and the sustain electrode 212b (hereinafter, referred to as a sustain discharge gap) is set near a value (usually about 80 μm) at which the minimum discharge voltage is obtained in the Paschen curve, and the external sustain voltage VSUS is 180 ~
It is suppressed to 200V.

[0008] Further, as shown in FIG.
a, 212b are replaced with transparent electrodes 2121a, 2121b,
In some cases, the metal buses 2122a and 2122b make the discharge spread by a transparent electrode. Such a technique is effective for improving the luminous efficiency. However, in such a PDP, the luminous efficiency is about 1 lm / W, and this value is about one fifth of that of a CRT. It is.

In order to improve the luminous efficiency, it is also effective to set a high partial pressure of xenon gas in the sealed gas. For example, in US Pat. No. 5,770,921, 10 vol% of xenon (Xe) is used. Techniques for improving luminous efficiency by setting as described above have been disclosed, but it is desired to obtain higher luminous efficiency. SUMMARY OF THE INVENTION An object of the present invention is to provide a PDP, a PDP display device, and a method of driving the PDP capable of greatly improving luminous efficiency as compared with the related art while keeping the discharge sustaining voltage low.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first substrate having a first electrode and a second electrode covered with a dielectric layer formed in parallel with each other; And a second substrate on which a third electrode is formed in a direction orthogonal to the second electrode is disposed so as to oppose via a partition, and is partitioned by the partition between the first substrate and the second substrate. In a PDP in which a discharge gas is sealed in a space, a mixed gas containing xenon of 5 vol% or more and less than 100 vol% is used as the discharge gas, or the xenon partial pressure is set to 2 kPa or more, and the first electrode and the first electrode are mixed. The gap between the two electrodes is set to be larger than the height of the discharge space. here,
The “height of the discharge space” is the length of the discharge space in the PDP thickness direction, and substantially corresponds to the distance between the first electrode and the third electrode and the distance between the second electrode and the third electrode.

According to this structure, since the xenon partial pressure is set high, a large amount of Xe is present in the discharge space, so that high luminous efficiency can be obtained during driving. The reason is that, as explained in US Pat. No. 5,770,921, when the amount of Xe in the discharge space is large, the amount of generated ultraviolet rays increases, and the molecular beam of Xe molecules in the emitted ultraviolet light causes It is conceivable that an increase in the ratio of the excitation wavelength (wavelength 173 nm) improves the conversion efficiency of the phosphor into visible light.

Further, according to the above configuration, the first electrode and the second electrode
Since the gap between the electrodes is set to be larger than the height of the discharge space, when a sustain pulse whose polarity is alternately applied between the first electrode and the second electrode is applied to maintain the discharge, the discharge path is increased. And a positive column discharge is formed. The positive column discharge is
As is well known, since the discharge mode is high in luminous efficiency, high luminous efficiency can be obtained by using this discharge mode.

When the sustaining pulse is applied to maintain the discharge, the distance between the second electrode and the third electrode or the distance between the first electrode and the third electrode is shorter than the gap between the first electrode and the second electrode. Since the discharge is started between the electrodes, the voltage for starting the discharge can be suppressed low. That is, in this PDP, when a sustaining pulse is applied during the sustaining discharge to make the second electrode side negative, the discharge starts between the second and third electrodes even if the applied voltage is low. The discharge spreads toward the first electrode. On the other hand, when a sustaining pulse in which the first electrode has a negative polarity is applied, the discharge starts between the first and third electrodes even if the applied voltage is low, and the discharge extends toward the second electrode. I do. Therefore, the discharge can be maintained at a relatively low voltage despite the large gap between the first electrode and the second electrode.

Therefore, the PDP of the present invention is a conventional PDP.
The luminous efficiency can be greatly improved while keeping the discharge voltage low as compared with DP. Note that the first electrode and the second electrode
The larger the gap between the electrode and the electrode is, the higher the discharge efficiency can be obtained, but the upper limit is actually limited by the cell pitch and the drive voltage, and can be set to several times the height of the discharge space.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Overall Description of PDP Configuration and Driving Method] FIG. 1 is a perspective view showing a schematic configuration of an AC surface discharge type PDP according to an embodiment of the present invention.
The PDP includes a front panel 10 in which a first electrode (scanning electrode) 12a, a second electrode (sustain electrode) 12b, a dielectric layer 13, and a protective layer 14 are disposed on a front glass substrate 11, and a rear glass substrate 21. A rear panel 20 on which a third electrode (address electrode) 22 is disposed is arranged in parallel with each other at an interval with the electrodes 12a, 12b and the third electrode 22 facing each other. . And the front panel 10
The gap between the panel and the rear panel 20 is a stripe-shaped partition wall 24.
A discharge space 30 is formed by partitioning the discharge space, and a discharge gas is sealed in the discharge space 30.

On the back panel 20 side, a phosphor layer 25 is disposed on the partition wall 24. This phosphor layer 25
Red, green, and blue are repeatedly arranged in this order.
Wants to 0. Each of the first electrode 12a, the second electrode 12b, and the third electrode 22 is a striped metal electrode, and is formed, for example, by applying an Ag paste in a line shape and baking it. First electrode 12a, second electrode 1
2b is arranged in a direction orthogonal to the partition wall 24, and the third electrode 22 is arranged in parallel with the partition wall 24 (see FIG. 2).

As will be described in detail later, the paired first
The gap (sustain discharge gap) between the electrode 12a and the second electrode 12b is equal to the height of the discharge space 30 (the distance in the panel thickness direction,
Hereinafter, it is referred to as “opposed discharge gap”. ) Is set larger. The dielectric layer 13 is a layer made of a dielectric material disposed over the entire surface of the front glass substrate 11 on which the electrodes 12a and 12b are disposed, and is generally a lead-based low-melting glass or bismuth-based low-melting glass. Melting point glass is used.

The protective layer 14 is made of magnesium oxide (Mg).
O) and other thin layers made of a material having a high secondary electron emission coefficient, and cover the entire surface of the dielectric layer 13. The partition wall 24 is formed of a glass material, and protrudes from the surface of the rear glass substrate 21. Although the dielectric layer 13 is provided only on the front panel 10 side here, the third electrode 22 and the phosphor layer 25 are also provided on the rear panel 20 side.
And a dielectric layer may be provided between them.

The composition of the discharge gas is a mixed gas of xenon (Xe) and at least one of helium (He), neon (Ne), argon (Ar) and the like conventionally used for PDP. However, the xenon partial pressure was set to 2 kP so that the amount of xenon in the discharge space increased.
Set to a or more. This is because the charging pressure of the discharge gas is 40
When kPa to 67 kPa, the mixing ratio of xenon is 5
It corresponds to the range of vol% or more.

Although described later in detail, in order to obtain a luminous efficiency higher than 2 kPa, the xenon partial pressure is increased to 6.7 kP.
It is preferable to set the pressure to a or more, more preferably 10 kPa or more.
On the other hand, the upper limit of the xenon partial pressure is considered to be about 16 kPa from the current performance of the drive circuit. FIG. 2 shows this PDP
FIG. 2 is a diagram showing a configuration of a display device in which a drive circuit 100 is connected to the display device. The electrodes 12a and 12b and the third electrode 22 are disposed orthogonal to each other, and a discharge cell is formed at a place where the electrodes intersect in a space between the front glass substrate 11 and the rear glass substrate 21. One pixel is formed by three discharge cells (red, green, and blue) adjacent to each other in the direction in which the first electrode 12a and the second electrode 12b extend.

Adjacent discharge cells are separated by partition walls 24 so that discharge diffusion to adjacent discharge cells is cut off, so that high-resolution display can be performed. This PDP is driven using an in-field time division gray scale display method. FIG. 3 is a diagram showing an example of a method of dividing one field when expressing 256 gradations, where the horizontal direction indicates time, and the shaded portion indicates a discharge sustaining period.

In the example of the division method shown in FIG. 3, one field is composed of eight subfields, and the ratio of the sustaining periods of each subfield is 1, 2, 4, 8, 1
6, 32, 64, and 128, and 256 gradations can be expressed by a combination of these 8-bit binaries. In addition, in the NTSC system television video, since the video is composed of 60 field images per second, the time of one field is set to 16.7 ms.

Each subfield has a setup period,
It is composed of a series of sequences of an address period and a discharge sustaining period, and an image of one field is displayed by repeating the operation for one subfield eight times.
FIG. 4 is a chart showing the timing at which the drive circuit 100 applies a pulse to each electrode in one subfield.

In the chart of FIG. 4, FIG.
The voltage waveform Vx applied to the electrode 12a is shown in FIG.
A voltage waveform Vy applied to the second electrode 12b, and (c)
Is a voltage waveform Va applied to the third electrode 22. FIG. 4D is a waveform showing the absolute value of the current flowing by the discharge. In the address period, a pulse is sequentially applied to the plurality of first electrodes, and the pulses are applied to selected ones of the plurality of third electrodes in accordance with the application. However, in FIG. , The second electrode 12b and the third electrode 22 only.

During the initialization period, a positive polarity initialization pulse is applied to the entire first electrode 12a at once,
The wall charges are accumulated on the protective layer 14 and the phosphor layer 25, and the states of all the discharge cells are initialized. During the address period,
While sequentially applying a negative scanning pulse to the first electrode 12a, a positive data pulse is applied to a selected electrode in the third electrode 22. As a result, in a cell to be turned on (referred to as a “lighted cell”),
Discharge occurs between the first electrode 12a and the third electrode 22,
Wall charges are formed on the surface of the protective layer 14, and pixel information for one screen is written.

During the sustain period, the first electrode 12a and the second electrode
An AC voltage is applied to the electrode 12b at a time. As a result, plasma discharge occurs selectively in the discharge cells in which the wall charges are accumulated. This discharge continues for a period corresponding to the weight of the subfield. (Relationship Between Sustain Discharge Gap and Opposing Discharge Gap in the Present Embodiment) FIG. 5 is a cross-sectional view of the PDP cut along the third electrode 22.

The sustain discharge gap dss between the first electrode 12a and the second electrode 12b is set to the opposite discharge gap dsa (third
It is set to be larger than the distance between the surface of the phosphor layer 25 and the surface of the protective layer 14 on the center line of the electrode 22 (d).
ss> dsa). Here, in designing the AC surface discharge type PDP, the size of the opposing discharge gap dsa is set to a distance at which the address discharge can be easily performed. However, this distance is also substantially changed depending on conditions such as the cell pitch and the pressure of the discharge gas. It will be decided.

On the other hand, the sustain discharge gap dss is conventionally set on the basis of the Paschen's law as described above. In this case, the sustain discharge gap dss is smaller than the opposing discharge gap dsa. Therefore, when the sustain discharge gap dss is set to be larger than the opposing discharge gap dsa as in the present embodiment, the discharge length during the sustain discharge is set to be longer than that of the conventional PDP.

The value that can be set as the sustain discharge gap dss is also limited by the cell pitch.
It can be set to be several times as large as the opposing discharge gap dsa. That is, the first electrode 12a and the second electrode 12b
The upper limit of the distance dst between the outer edges is determined by the cell pitch.
The upper limit is also determined, but within this limit, the sustain discharge gap d
In order to set ss as large as possible, the first electrode 12
It is desirable that the electrode a and the second electrode 12b are formed of only metal electrodes without using a transparent electrode, and the electrode width is reduced as much as possible. If the electrode width is reduced in this manner, the sustain discharge gap dss can be secured about several times the opposing discharge gap dsa.

When the sustain discharge increases the gap dss, the drive voltage rises, albeit slightly, so that the upper limit is also determined from this drive voltage. However, the drive can be performed up to 5 to 6 times the opposing discharge gap dsa. Make sure there is. On the other hand, in order to increase the discharge length during the sustain discharge as much as possible, it is desirable to set the sustain discharge gap dss as large as possible. From this point, even within the range larger than the opposing discharge gap dsa, the opposing discharge gap dsa is further increased. It is preferable to set the range larger than 1.2 times, 1.5 times or more, 2 times or more, and 3 times or more.

Table 1 shows an example of the design parameters of the PDP according to the present embodiment.

[0032]

[Table 1]

According to the design parameters, the first electrode 1
The sustain discharge gap dss between 2a and the second electrode 12b is 4
00 μm, which is the value of the opposing discharge gap dsa.
(90 μm), which is 5 times as large as the sustain discharge gap (80 μm) of the conventional PDP of FIG.
This is a large value close to double. (Pulse applied in each period and discharge operation accompanying it) Next, based on the chart of FIG.
The pulse applied during each of the address and sustain periods and the discharge operation will be described. Note that the pulse waveform applied by the drive circuit 100 is substantially the same as that conventionally used for a PDP, but is characterized by a discharging operation.

In FIG. 4A, the wall voltages generated in the phosphor layer 25 on the third electrode 22, the dielectric layer 13 and the protective layer 14 on the first electrode 12a are shown by broken lines, and FIG. In), the dashed lines indicate the wall voltage generated in the phosphor layer 25 on the third electrode 22, the dielectric layer 13 on the second electrode 12b, and the protective layer 14. In FIG. 4, the polarity of the accumulated wall charges is shown on the broken line.

The above-mentioned wall voltage is generated by wall charges accumulated on the protective layer 14 or the phosphor layer 25 with the occurrence of discharge. Then, the difference between the applied voltage shown by the solid line and the wall voltage shown by the broken line corresponds to the voltage applied to the discharge space between the respective electrodes. 6 and 7 are views for explaining the discharging operation in the PDP. Description will be made with reference to this.

Initialization period: In the first half of the initialization period, the first
A falling gradient voltage is applied to the third electrode 22 to both the electrode 12a and the second electrode 12b. By applying the voltage to the first electrode 12a and the second electrode 12b in this manner,
The protective layer 14 having a relatively large secondary electron emission coefficient serves as a cathode and discharge is easily started, and a weak discharge occurs in the first opposed discharge space and the second opposed discharge space. With this discharge, initial charges are formed in the first opposed discharge space 30a and the second opposed discharge space 30b.

In the middle of the initialization period, a rising voltage with a relatively large amplitude is applied to the first electrode 12a and the second electrode 12b with respect to the third electrode 22. by this,
Discharge occurs in the first opposed discharge space 30a and the second opposed discharge space 30b, and as a result, negative charges are accumulated in the protective layer 14 on the first electrode 12a and the second electrode 12b. In the second half of the initialization period, a ramp voltage falling with respect to the third electrode 22 is applied to the first electrode 12a. Thereby, the first
Discharge occurs in the opposing discharge space 30a. As a result, part of the negative charge on the surface of the protective layer 14 on the first electrode 12a is erased.

While the ramp voltage is applied, a discharge current continuously flows, and a voltage of about the discharge sustaining voltage Vs is constantly applied to the first opposed discharge space 30a. Therefore, when the initialization period ends, the difference between the applied voltage and the wall voltage is substantially equal to the sustaining voltage Vs in the discharge space. In FIG. 4, at the end of the initialization period, the first opposed discharge space 3
The voltage (Vsx-a) applied to Oa is shown.

The above-mentioned initialization pulse waveform is almost the same as that described in Japanese Patent Application Laid-Open No. 12-267625, and by using such a waveform,
Initialization can be performed in a relatively short time, and the discharge maintenance period can be lengthened accordingly. Address period: In the address period, the first electrode 12
a, a bias voltage Vab is applied to the first electrode 1
By sequentially applying a negative pulse voltage while sequentially scanning 2a and applying a positive data pulse (voltage Va) to the third electrode 22 corresponding to the lighting cell, discharge is selectively performed only in the lighting cell. Wake up.

During this time, the first electrode 12b is
A positive voltage is continuously applied to the electrode 12a.
As a result, in the lighting cell, at the time t1, the first
First opposed discharge space 3 between electrode 12a and third electrode 22
0a is applied with the voltage (Vsx−a + Va), and the first
Discharge starts in the opposing discharge space 30a.

Here, the above-mentioned voltage (Vsx-a) is
Since the voltage is substantially equal to the sustaining voltage of the first opposed discharge space 30a, the discharge can be started even if the value of the data pulse voltage Va is relatively small. And the second as described above
Since a positive voltage is applied to the electrode 12b with respect to the first electrode 12a, the discharge generated in the first opposed discharge space 30a extends in the direction of the second electrode 12b, and the second discharge occurs at time t2. A discharge is also formed in the second opposed discharge space 30b between the electrode 12b and the third electrode 22.

As a result, the protective layer 1 on the first electrode 12a
4, a positive charge is accumulated, and a negative charge opposite thereto is accumulated on the protective layer 14 on the second electrode 12b (see FIG. 6A). On the other hand, no data pulse is applied to the third electrode 22 corresponding to the non-lighted cell, and no discharge occurs. Therefore, in the non-lighting cell, at the end of the initialization period, the charge accumulated on the protective layer 14 on the first electrode 12 and the second electrode 12b is kept almost as it is.

Discharge sustain period: During the discharge sustain period, the amplitude VSUS is applied to each of the first electrode 12a and the second electrode 12b.
Then, the first sustain pulse and the second sustain pulse having the opposite polarity to the first sustain pulse are alternately applied. 6 and 7 schematically show a cross section of the PDP according to the present embodiment, and also show the applied voltage, the state of the wall charge, and the state of the discharge plasma when the first sustain pulse is applied. 14 is omitted.

Referring to FIGS. 6 and 7, a mechanism in which the discharge started in one opposed discharge space 30a extends to the other opposed discharge space 30b during the sustain period will be described.
This will be described in detail. As shown in FIG. 4, at time t3, the external sustain voltage VSUS is applied to the first electrode 12a, and the second electrode 12b is grounded.

Therefore, the phase of the first sustain pulse applied at the time t3 is negative on the second electrode 12b side and positive on the first electrode 12a. In the address period, since the negative wall charges are accumulated on the dielectric layer 13 on the second electrode 12b in the lighting cell, the first electrode 12b is so set as to have the negative polarity. By applying the sustain pulse, the discharge in which the second electrode 12b is on the cathode side in the second opposed discharge space 30b is started.

Positive wall charges are accumulated on the phosphor layer 25 (this is due to the second electrode 12 during the address period).
This is because, while a large positive voltage is applied to b, the third electrode 22 having a low potential attracts positive charges. ), The discharge generated in the second opposed discharge space 30b extends in the direction of the first electrode 12a. FIG. 6B shows a state where the discharge has started in the second opposed discharge space 30b. When the discharge starts in the second opposed discharge space 30b, a large amount of positive charges and negative charges are generated, and the second electrode 12b and the third electrode 22 respectively.
To form wall charges. The wall voltage generated by the wall charge acts to cancel the voltage applied to the second opposed discharge space 30b and stop the discharge.

When the dielectric layer 13 on the second electrode 12b and the phosphor layer 25 on the third electrode 22 are compared, the latter has a smaller dielectric constant, so that the surface of the dielectric layer 13 (the second electrode 12
b surface), the surface of the phosphor layer 25 (third electrode 22 side)
The accumulation of wall charges progresses faster. As a result, the anode end of the discharge moves in search of the surface of the phosphor layer 25 into which negative charges can flow.

On the other hand, the first electrode 12a is connected to the second electrode 12b
Since the voltage of the positive polarity is applied, the moving direction of the discharge is the direction of the first electrode 12a. FIG. 6 (c)
The anode end of the discharge shows a state in which positive charges accumulated on the phosphor layer 25 are canceled out and extended in the direction of the first electrode 12a. Then, at time t4 in FIG. 4, the anode end of the discharge is connected to the first electrode 12a as shown in FIG.
After reaching the upper side, a discharge is also formed in the first opposed discharge space 30a.

FIG. 7B shows a state immediately before the discharge stops. FIG. 7C shows a state where the discharge is stopped as a result of accumulation of wall charges on the dielectric layer 13 and the phosphor layer 25. The above discharge occurs in the first opposed discharge space 30a.
A negative wall charge is formed on the dielectric layer 13 on the first electrode 12a, and a positive wall charge is formed on the phosphor layer 25 on the third electrode 22. Thus, negative charges are accumulated in the dielectric layer 13 on the first electrode 12a, and positive charges are accumulated in the dielectric layer 13 and the phosphor layer 25 on the second electrode 12b.

On the other hand, the second opposed discharge space 3 where the discharge has started
On the 0b side, the wall voltage is almost completely erased as shown in FIG. As described above, the second opposed discharge space 3
Since a long discharge is formed from 0b to the first opposed discharge space 30a, a large amount of ultraviolet rays is emitted by the positive column discharge. Here, the positive column generally indicates a filamentary discharge generated in a discharge space having a long distance between electrodes.

In FIG. 7C, the distribution of the wall charges in FIG. 6A at time t3 is reversed. Therefore, at time t5 in FIG.
2a and the second electrode 12b are exchanged, and the application of the second sustain pulse is started in the same manner as at the time t3. That is, a positive external sustain voltage VSUS is applied to the second electrode 12b, and the first electrode 12a is grounded.

Thus, the same sustain discharge can be repeated. As described above, the discharge operation in the sustain discharge period of the present embodiment is different from the surface discharge operation of the conventional PDP of FIG.
Rather, it can be said that the discharge is close to the counter discharge. Note that the external sustain voltage VSU is applied to the first electrode 12a at the time t3.
The timing to start applying S and the timing to ground the second electrode 12b are determined by the second electrode 12b in the second opposed discharge space.
Any timing may be used as long as the discharge is started so that the b side becomes a cathode, and the following forms are conceivable.

For example, the application of the external sustain voltage VSUS to the first electrode 12a may be started first (discharge does not start here), and the discharge may be started by grounding the second electrode 12b. The application of the external sustain voltage VSUS to the first electrode 12a may be started from the start of the discharge to the end of the discharge with the second electrode 12b grounded. In the latter case, the discharge current is reduced, so that the load on the drive circuit is reduced.

(Effects of PDP of this Embodiment) As described above, in the PDP of this embodiment, the partial pressure of xenon is 2 kPa or more (the charging pressure of the discharge gas is 40 kPa or more, and the mixing ratio of xenon in the discharge gas is Is 5vol% or more)
, The amount of xenon in the discharge space 30 increases. At the same time, by setting the sustain discharge gap dss to be larger than the height dsa of the discharge space 30, the discharge length can be increased while the discharge voltage is kept low, so that the discharge voltage is kept low and the discharge efficiency is improved. Here, we explain why and why.

First, the reason why the sustain discharge voltage can be suppressed low will be described. If the sustain discharge gap dss between the first electrode 12a and the second electrode 12b is large, the first electrode 12a and the second electrode 12
If the discharge is maintained between b, the discharge start voltage (VfSS) becomes extremely high according to Paschen's law.

When the discharge starting voltage (VfSS) increases,
The external drive voltage VSUS also increases. this is,
When the sum of the wall voltage of the dielectric layer 13 on the first electrode 12a and the wall voltage of the dielectric layer 13 on the second electrode 12b is VwSS, the voltage applied to the discharge space is the external drive voltage VSU
S + VwSS, so that the first
This is because in order to maintain the discharge between the electrode 12a and the second electrode 12b, the relationship of (Equation 1) must be satisfied.

VfSS <VSUS + VwSS (Equation 1) However, in the present embodiment, as described in the discharge operation, when the sustain discharge is performed between the first electrode 12a and the second electrode 12b, Between the first electrode 12a and the third electrode 22 (first opposed discharge space 30a) or the second
Between the electrode 12b and the third electrode 22 (the second opposed discharge space 3
Since the discharge is started at 0b), the discharge starting voltage VfSS is suppressed to a considerably low value, and therefore, the external drive voltage VSUS is also suppressed to a relatively low value.

Next, as described in the discharge operation, when the sustain pulse is applied, the first opposed discharge space 30
a, the discharge is started with the first electrode 12a on the cathode side, and the second opposed discharge space 3
When the discharge is started at 0b, the discharge starting voltage can be further reduced by applying the second electrode 12b to the cathode side so as to start the discharge, for the following reason.

First, it is defined as follows. First electrode 12
The discharge space between a and the third electrode 22 is defined as a first opposed discharge space, and the discharge space between the second electrode 12b and the third electrode 22 is defined as a second opposed discharge space. First electrode 12a and second electrode 1
2b (distance dss between electrodes) to V
fSS.

The discharge starting voltage in the first opposed discharge space when the first electrode 12a is on the lower potential side with respect to the third electrode 22 is defined as VfSa. Similarly, the discharge start voltage of the second opposed discharge space when the second electrode 12b is on the low potential side is also VfSa. When the third electrode 22 is on the low potential side with respect to the first electrode 12a, the discharge starting voltage of the first opposed discharge space is Vfa
S. Similarly, the discharge starting voltage of the second opposed discharge space when the third electrode 22 is on the low potential side is also VfaS.

At this time, when VfSa and VfaS are compared, they are the discharge starting voltages when the discharge polarities are opposite to each other, but VfSa is the protective layer 1 having a high secondary electron emission coefficient.
On the other hand, VfaS is the discharge starting voltage when the cathode layer is used as the phosphor layer 25 whose secondary electron emission coefficient is considerably lower than that of the protective layer 14, whereas the discharge starting voltage is obtained when the 4 side is used as the cathode side. Since it is a voltage, there is a relationship of VfSa≪VfaS.

Therefore, when the protective layer 14 is on the cathode side, discharge is started at a lower discharge start voltage. Next, FIG.
The effect of the present invention will be described based on data of Nos. 10 to 10. FIG. 8 is a characteristic diagram showing the relationship between the sustain discharge gap d and the discharge voltage, and the curve Q shows the third electrode 2 as in the present embodiment.
2 shows a case where a sustain discharge is generated between the first electrode 12a and the second electrode 12b via the second electrode 2. On the other hand, the curve P indicates that the third electrode 22 does not exist and the first electrode 12a and the second electrode 1
2B shows a case in which a sustain discharge is performed between the discharge lamps 2b and 2b.

The curve P follows the so-called Paschen's law, in which the discharge voltage has a minimum value at a relatively small discharge gap d, and the discharge voltage sharply increases as the sustain discharge gap d increases. On the other hand, in the curve Q, even if the sustain discharge gap d becomes large, the discharge voltage only slightly increases, and is maintained at a value about the discharge voltage in the opposed discharge space. This is because the facing discharge gap is constant, and the facing discharge gap determines the discharge voltage.

According to FIG. 8, the sustain discharge gap d
In a region where is small, the curve Q is larger than the curve P, but above a certain gap length dc, the curve Q is lower than the curve P. That is, the discharge voltage becomes lower when the light passes through the third electrode 22 and the phosphor layer 25. This gap length dc is called a characteristic discharge length. This characteristic discharge length dc is substantially equal to the opposing discharge gap dsa.

Therefore, when the sustain discharge gap d is larger than the opposing discharge gap dsa, it can be seen that the driving can be performed at a discharge voltage lower than the discharge voltage predicted from the curve P. This result confirms that the PDP of the present embodiment can be driven by a discharge considerably lower than the discharge voltage predicted from the sustain discharge gap d based on Paschen's law.

FIG. 9 shows a conventional PDP (type of FIG. 11) in which the discharge gap is smaller than the discharge space height, and a PDP of the present embodiment type in which the discharge gap is larger than the discharge space height.
It is a result of examining a change in luminous efficiency of DP with respect to a change in xenon partial pressure. Here, the adjustment of the partial pressure of xenon is made such that the total pressure of the discharge gas to be filled is constant at 67 kPa,
This was performed by changing the ratio of xenon in the discharge gas.

In the figure, the curve X shows the result for the conventional PDP, and the curve Y shows the result for the PDP of the present embodiment. In the figure, the xenon partial pressure is
It is shown as a ratio (%) to kPa. From FIG. 9, all the curves show that the luminous efficiency increases as the xenon partial pressure ratio increases, but the curve Y shows that the rate of increase of the efficiency with respect to the increase in the xenon partial pressure is considerably larger than that of the curve X. Understand.

This is because the effect of improving the luminous efficiency obtained by increasing the xenon partial pressure with respect to a PDP in which the discharge gap is larger than the height of the discharge space is obtained by increasing the xenon partial pressure with respect to a conventional PDP. It shows that the effect is remarkable exceeding the effect of improving the luminous efficiency. Further, as shown in FIG. 9, high luminous efficiency is obtained particularly in the range of the xenon partial pressure ratio of 10% or more (xenon partial pressure of 6.7 kPa or more).

In a conventional general PDP (a PDP in which the mixing ratio of Xe is about 5 vol% and the discharge gap is smaller than the height of the discharge space), the luminous efficiency is only about 1.0 lm / W. It can be seen that the higher the xenon partial pressure, the higher the luminous efficiency can be obtained. Also, as in the present embodiment, the discharge gap is larger than the discharge space height, and the xenon partial pressure is 2 kPa or more (for example, if the total pressure of the discharge gas is 66.7 kPa, the xenon ratio is 3.3 vol%).
Above), the P of higher luminous efficiency can be obtained.
It can be seen that DP is obtained.

Although FIG. 9 shows the case where the total pressure is fixed and the ratio of xenon is changed, even when the xenon partial pressure is increased by changing the total pressure,
It was found that the luminous efficiency increased substantially in the same manner as in FIG. 9 as the xenon partial pressure increased. FIG. 10 shows how the luminous efficiency changes when the xenon partial pressure to be sealed is changed in the prototype PDP of the present embodiment. In this figure, the xenon partial pressure (kPa) is shown. And the luminous efficiency.

Although a mixed gas of neon and xenon is used in the above-mentioned prototype PDP, the same effect as in FIG. 10 can be obtained when helium, argon, krypton, or a mixed gas thereof is used instead of neon. Can be It is considered that the upper limit of the xenon partial pressure is actually determined by the withstand voltage of the drive circuit.

For example, in the prototype PDP shown in Table 1 above, the external sustain voltage VSUS is 340 V, the luminous efficiency is 2.
1 lm / W was achieved. Here, it is expected that higher luminous efficiency can be obtained if the xenon partial pressure can be further increased. However, in the current driving circuit, the upper limit is about 340 V from the above-mentioned external sustaining voltage in terms of the withstand voltage performance. Because it is considered, when the xenon partial pressure is set in a range exceeding 16 kPa, it can be said that actual driving is difficult.

From such a point, the xenon partial pressure is 16 k
It is considered appropriate to set the range to Pa or less. However, if the withstand voltage performance of the drive IC increases, the xenon partial pressure is reduced to 1
It is also possible to set the pressure higher than 6 kPa, for example, about 30 kPa of xenon partial pressure. According to FIG. 10, since the luminous efficiency rises with very good linearity with respect to the xenon partial pressure, when the xenon partial pressure is set to a high value of about 30 kPa, the luminous efficiency can be obtained from the graph of FIG. Can be expected to rise to about 3.5 lm / W.

In terms of the mixing ratio of xenon, when the total pressure of the discharge gas is about 66.7 kPa, the actual driving becomes difficult in the range where the xenon mixing ratio exceeds 20%. If the pressure is reduced, driving is possible even when the xenon mixture ratio exceeds 20%. As described above, in the AC PDP of the present embodiment, the xenon partial pressure is set to 2 kPa or more or 5% or more of the total pressure, and the gap between first electrode 12a and second electrode 12b is increased. By doing so, luminous efficiency can be significantly improved while suppressing an increase in drive voltage.

Also, in the case of a high-definition PDP, the opposing discharge gap dsa becomes considerably smaller, while the sustain discharge gap dss can be easily set to be considerably larger than the opposing discharge gap dsa.
It can also be said that the PDP of the present embodiment is particularly suitable for high definition specifications. (Modifications, etc.) In the above-described embodiment, the AC-type PDP that performs the address-sustain separation type drive has been described. However, other drive methods (for example, addressing sequentially for each line and maintaining immediately after that). The same effect can be obtained in an AC PDP driven by discharge driving.

The voltage waveforms applied in the initialization period and the address period are not limited to those in this embodiment, and wall charges are selectively formed in discharge cells according to image data. Anything should do. Further, in the above-described embodiment, a description has been given of a case where a strip-shaped partition wall parallel to the third electrode is formed. However, as long as a discharge space can be formed, a similar shape can be obtained with a cross-shaped shape. .

[0077]

As described above, the present invention relates to a first substrate in which a first electrode and a second electrode covered with a dielectric layer are formed parallel to each other, A second substrate on which a third electrode is formed in a direction orthogonal to the first substrate is disposed opposite to the second substrate via a partition, and discharge gas is supplied to a space between the first substrate and the second substrate partitioned by the partition. Xenon is used as a discharge gas in the sealed PDP for 5 vo.
Use a mixed gas containing l% or more and less than 100 vol%, or set the xenon partial pressure to 2 kPa or more, and set the gap between the first electrode and the second electrode larger than the height of the discharge space. This makes it possible to greatly improve the luminous efficiency while keeping the discharge voltage low as compared with the conventional PDP.

[Brief description of the drawings]

FIG. 1 shows an AC surface discharge type PD according to an embodiment of the present invention.
It is a perspective view which shows schematic structure of P.

FIG. 2 is a configuration diagram of a display device in which a driving circuit 100 is connected to the PDP.

FIG. 3 is a diagram illustrating an example of a method of dividing one field when driving the display device.

FIG. 4 is a chart showing a timing at which a drive circuit applies a pulse to each electrode in one subfield.

FIG. 5 is a cross-sectional view of the PDP taken along an address electrode.

FIG. 6 is a diagram for explaining a discharging operation in the PDP.

FIG. 7 is a diagram for explaining a discharging operation in the PDP.

FIG. 8 is a characteristic diagram showing a relationship between a sustain discharge gap and a discharge voltage.

FIG. 9 is a diagram showing the relationship between xenon partial pressure and luminous efficiency for a conventional PDP and a PDP of the present embodiment.

FIG. 10 is a diagram showing a relationship between xenon partial pressure (kPa) and luminous efficiency in the PDP of the embodiment.

FIG. 11 is a sectional view of a main part of a conventional PDP.

[Explanation of symbols]

 Reference Signs List 10 front panel 11 front glass substrate 12a first electrode 12b second electrode 13 dielectric layer 14 protective layer 20 rear panel 21 rear glass substrate 22 third electrode 24 partition wall 25 phosphor layer 30 discharge space 30a first opposed discharge space 30b first 2 opposed discharge space 100 drive circuit

Claims (11)

[Claims] A first electrode and a second electrode covered with a dielectric layer.
A first substrate having electrodes formed in parallel with each other;
A second substrate on which a third electrode is formed in a direction orthogonal to the electrodes and the second electrode is disposed to face through a partition, and is partitioned by the partition between the first substrate and the second substrate. A plasma display panel in which a discharge gas is sealed in a defined space, wherein the discharge gas contains xenon in an amount of 5 vol% or more and 100 vol% or more.
A plasma display panel, comprising: a mixed gas containing less than the first electrode, wherein a gap between the first electrode and the second electrode is set to be larger than a height of the discharge space. 2. A first electrode and a second electrode covered with a dielectric layer.
A first substrate having electrodes formed in parallel with each other;
A second substrate on which a third electrode is formed in a direction orthogonal to the electrodes and the second electrode is disposed to face through a partition, and is partitioned by the partition between the first substrate and the second substrate. A plasma display panel in which a discharge gas is sealed in a defined space, wherein the discharge gas is a mixed gas containing xenon, the xenon partial pressure is 2 kPa or more, and the first electrode and the second electrode Wherein the gap is set larger than the height of the discharge space. 3. A first electrode and a second electrode covered with a dielectric layer.
A first substrate having electrodes formed in parallel with each other;
A second substrate on which a third electrode is formed in a direction orthogonal to the electrodes and the second electrode is disposed to face through a partition, and is partitioned by the partition between the first substrate and the second substrate. A discharge gas sealed in a defined space, wherein the discharge gas is a mixed gas containing xenon, and the xenon partial pressure is in a range of 6.7 kPa or more and 16 kPa or less; A plasma display panel, wherein a gap between one electrode and the second electrode is set to be larger than a height of the discharge space. 4. A first electrode and a second electrode covered with a dielectric layer.
A first substrate having electrodes formed in parallel with each other;
A second substrate on which a third electrode is formed in a direction orthogonal to the electrodes and the second electrode is disposed to face through a partition, and is partitioned by the partition between the first substrate and the second substrate. A plasma display panel in which a discharge gas is sealed in a defined space, wherein the discharge gas is a mixed gas containing xenon, and the xenon partial pressure is in a range of 10 kPa or more and 16 kPa or less, and the first electrode A gap between the first electrode and the second electrode is set larger than a height of the discharge space. 5. A discharge in a discharge space between the second electrode and the third electrode is extended to the first opposed discharge space along the third electrode, and the first electrode and the The discharge in a discharge space between the third electrode and the third electrode is configured to extend to the second opposed discharge space along the third electrode.
5. The plasma display panel according to any one of 4. 6. A minimum voltage required for performing a surface discharge between the first electrode and the second electrode is set between the first electrode and the second electrode without passing through the third electrode. The plasma display panel according to any one of claims 1 to 4, wherein the panel has a panel structure that is smaller than a minimum voltage necessary for performing surface discharge in the above. 7. A writing step of writing an image by applying a writing pulse between a first electrode and a third electrode to the plasma display panel according to claim 1. After the writing step, the second electrode is disposed between the first electrode and the second electrode.
A driving method for displaying an image by repeating a discharge sustaining step of maintaining a discharge by alternately applying a first sustaining pulse in which the first electrode has a positive polarity and a second sustaining pulse having the opposite polarity to the electrode In the sustaining step, the timing at which the first sustaining pulse and the second sustaining pulse are applied is such that a discharge between the second electrode and the third electrode is caused by the application of the first sustaining pulse. In the space, a voltage is applied so that the discharge is started with the second electrode serving as the cathode side. With the application of the second sustain pulse, the first electrode is
Driving a plasma display panel, wherein a voltage is set in a discharge space between the first electrode and the third electrode so that a discharge is started with the first electrode serving as a cathode. Method. 8. A sustain pulse voltage applied to a discharge space between the first electrode and the second electrode during the sustain period, the sustain pulse voltage being applied to the first electrode and the second electrode without passing through the third electrode.
8. The method according to claim 7, wherein the voltage is lower than a minimum voltage required to perform a surface discharge between the electrodes and the electrodes. 9. A plasma display panel display device comprising: the plasma display panel according to claim 1; and a driving unit that drives the PDP. 10. A writing unit for writing an image by applying a writing pulse between the first electrode and the third electrode, and a driving unit for writing an image between the first electrode and the second electrode. Discharge sustaining means for maintaining a discharge by alternately applying a first sustain pulse in which the first electrode has a positive polarity to the second electrode and a second sustain pulse having a polarity opposite to the first sustain pulse, When the discharge sustaining means applies the first sustaining pulse, the discharge in the second opposed discharge space causes the discharge between the first electrode and the third electrode along the third electrode. When the discharge sustaining means applies the second sustaining pulse while extending to the discharge space, the discharge in the first opposing discharge space causes the discharge of the second electrode and the third electrode along the third electrode. To the discharge space between 10. The plasma display device according to claim 9, which has such a panel structure. 11. The sustaining discharge voltage applied between the first electrode and the second electrode by the discharge sustaining means of the driving unit may be a voltage between the first electrode and the second electrode without passing through the third electrode.
11. The plasma display device according to claim 10, wherein the voltage is lower than a minimum voltage required for performing a sustain discharge between the electrode and the electrode.