JP2003043987A - Plasma display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma display device capable of realizing high luminance and high efficiency without causing any self-discharge. SOLUTION: This plasma display device has a plasma display panel, in which a plurality of scan electrodes and a plurality of sustenance electrodes are arranged on one board of two boards which are disposed oppositely so as to form discharge spaces between them and xenon having partial pressure of >5% is filled in the discharge spaces, and a driving means for driving the plasma display panel. The driving means impresses negatively polar sustaining pluse whose peak value is Vs and whose potential changes in a direction of decreasing the pontential (from the peak value Vs to zero) alternately to the scan electrodes and the sustenance electrodes.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device. 2. Description of the Related Art As shown in a sectional view of FIG. 6, an AC type plasma display panel (hereinafter referred to as "panel") has two glass surfaces so as to form a discharge space 1 therebetween. The substrate 2 and the rear substrate 3 made of glass are arranged to face each other. The discharge space 1 is filled with neon (Ne) and xenon (Xe) that emit ultraviolet rays by discharge, and the partial pressure of Xe is usually 5% of the total gas pressure.
A plurality of discharge electrodes composed of scan electrodes 4 and sustain electrodes 5 are arranged on the front substrate 2, and a dielectric layer 6 is formed to cover the scan electrodes 4 and the sustain electrodes 5. A protective film 7 made of magnesium oxide (MgO) or the like is formed. The scanning electrode 4 includes a transparent electrode 4a and a metal electrode 4b.
And the sustain electrode 5 is composed of a transparent electrode 5a and a metal electrode 5b. On the back substrate 3, a plurality of data electrodes 8 are arranged in parallel with each other in a direction orthogonal to the scanning electrodes 4 and the sustain electrodes 5, and separate the data electrodes 8 to form the discharge space 1. Partition walls 9 are provided between the data electrodes 8. A phosphor layer 10 is formed to cover the side surfaces of the data electrode 8 and the partition 9. Then, a discharge cell is formed at the intersection of scan electrode 4 and sustain electrode 5 with data electrode 8. A conventional plasma display device has such a conventional panel and a driving means for driving the panel. Next, a method for displaying image data on a conventional panel will be described. The gradation display of an image is performed by dividing one field period into a plurality of subfields having a weight of a light emission period based on a binary system and combining the subfields to emit light. Each subfield has an initialization period, an address period, and a sustain period. In order to display image data, different signal waveforms are applied to each electrode during the initialization period, the address period, and the sustain period. During the initialization period, for example,
A pulse voltage having a positive polarity with respect to the sustain electrode 5 and the data electrode 8 is applied to all the scan electrodes 4 to accumulate wall charges on the protective film 7 and the phosphor layer 10. In the address period, scanning is performed by sequentially applying a negative pulse to all the scanning electrodes 4. When there is image data, when a positive data pulse is applied to the data electrode 8 while scanning the scanning electrode 4, a discharge occurs between the scanning electrode 4 and the data electrode 8,
Wall charges are formed on the surface of the protective film 7 on the scan electrode 4. In the following sustain period, the scanning electrode 4 is kept for a certain period.
A sustain pulse having a voltage sufficient to maintain a discharge is alternately applied between the sustain electrode and the sustain electrode 5. FIG. 7 (a),
(B) shows the waveform of the sustain pulse applied to the scan electrode 4 and the sustain electrode 5, respectively. The sustain pulse has a peak value of V _SO and a potential increasing direction (a direction from 0 to V _SO ). The positive polarity pulse changes to Due to the sustain pulse, the scan electrodes 4 in the discharge cells having image data
Discharge plasma is generated between the electrode and the sustain electrode 5, and the phosphor layer 10 emits light by excitation each time a sustain pulse is applied. No discharge occurs in the discharge cells to which no data pulse is applied during the address period, and no excitation light emission of the phosphor layer 10 occurs. FIG. 7C shows a light emission waveform, which emits light every time the sustain pulse rises (the potential changes from 0 to V _SO ). FIG. 8 shows a change in the luminous efficiency of the panel with respect to the peak value (sustain voltage) of the sustain pulse during the sustain period when the panel is driven as described above. The panel is filled with neon (Ne) and xenon (Xe), and the partial pressure of Xe is 5, 7, 10 and 20%. As can be seen from this figure, the luminous efficiency of the panel is 1.1 lm at maximum.
/ W, which decreases with an increase in the sustain voltage. Further, since the luminance of the panel increases with an increase in the sustain voltage, it has been difficult to obtain a panel with high luminous efficiency and high luminance. In order to increase the luminance of the panel, Japanese Patent Application Laid-Open No. 8-314405 discloses that a sustain pulse having a positive polarity shown in FIGS. When applied to the electrodes, the peak value V _S1 of the sustain pulse is set to a value lower than the discharge start voltage Vf and the closest to the discharge start voltage Vf within a range where no malfunction occurs, and the length of the energization period Ts is set to the end. It is disclosed that the wall voltage is set to exceed the discharge starting voltage Vf at a point in time. Thus, as shown in FIG. 9C, light is emitted not only when the sustain pulse rises but also when the sustain pulse falls (the potential changes from V _S1 to 0).
Light emission due to the fall of the sustain pulse utilizes discharge (self-discharge) generated by wall voltage due to accumulated charge on the dielectric layer, and light emission due to normal discharge and light emission due to self-discharge occur alternately. ing. FIG. 9 (c)
By causing the light emission as shown in (1), the number of times of light emission can be doubled the number of times of application of the sustain pulse, thereby improving the luminance. However, the self-discharge generated by the panel driving method described in Japanese Patent Application Laid-Open No. 8-314405 is caused by the wall voltage and the sustain pulse caused by the accumulated charge on the dielectric layer. Unlike a normal discharge that occurs at the voltage that is the sum of the peak value, it occurs only due to the wall voltage due to the accumulated charge on the dielectric layer, and the wall voltage variation directly affects the emission intensity variation due to self-discharge. I do. In particular, when the screen is large or the number of discharge cells is large, the luminous intensity due to self-discharge varies considerably as the variation in wall voltage increases, and it is difficult to display the entire screen cleanly without uneven brightness. there were. The present invention has been made to solve such a problem, and an object of the present invention is to provide a plasma display device which realizes high luminance and high luminous efficiency without generating self-discharge. In order to achieve this object, a plasma display device according to the present invention scans one of two substrates disposed opposite to each other so as to form a discharge space therebetween. A plasma display panel formed by arranging a plurality of electrodes and sustain electrodes and enclosing xenon with a partial pressure exceeding 5% in the discharge space, and a scan electrode and a sustain electrode of the plasma display panel during a sustain period. Driving means for applying a pulse of negative polarity. With this configuration, a plasma display device with high luminance and high luminous efficiency can be obtained without causing self-discharge. An embodiment of the present invention will be described below with reference to the drawings. A plasma display device according to an embodiment of the present invention has a panel and driving means for the panel, and FIG. 2 shows the structure of the panel. In the panel structure, the same parts as those shown in FIG. 6 are denoted by the same reference numerals. The difference between the panel structure of FIG. 2 and that of FIG. 6 is that the scanning electrode 11 and the sustaining electrode 12 do not use transparent electrodes and use metal. It is composed of electrodes. FIGS. 1A and 1B show voltage waveforms in a sustain period applied to the scan electrodes 11 and the sustain electrodes 12, respectively, by the panel driving means. In the present embodiment, unlike the waveforms shown in FIGS. 7 and 9, the peak value is V _S
In it and sustain pulse to be changed in a direction (direction from V _S to 0) the potential is reduced (negative sustain pulse) is applied alternately to the sustain electrode 12 and scan electrode 11. FIG. 1C shows a light emission waveform, in which a sustain discharge is generated as the sustain pulse is applied, and light is emitted. That is, although the sustain pulse falls (potential toward 0 from V _S) is emitting light for each sustain pulse rises (the potential is directed from 0 to V _S) is not sometimes sustain discharge occurs. That is, the self-discharge described above does not occur. Therefore, it is possible to prevent the occurrence of luminance unevenness, which has been a problem in the conventional panel, and to obtain a display quality superior to that of the conventional panel. When the sustain pulse of the present embodiment is applied, not only between the scan electrode 11 and the sustain electrode 12, but also between the scan electrode 11 or the sustain electrode 12 and the data electrode 8 to which the sustain pulse is applied. It was confirmed that discharge occurred even during the period. This is because, for example, when a sustain pulse of negative polarity is applied to the scan electrode 11, the scan electrode 11 side becomes negative with respect to the data electrode 8 side due to the negative wall voltage accumulated on the dielectric layer 6, so that ions Since secondary electrons are generated by colliding with the protective film 7, the scanning electrodes 11 and the data electrodes 8 are formed.
It is considered that a discharge occurs between the first and second states. Next, in the case of the plasma display device of the present embodiment, that is, when the panel of FIG. 2 is driven by the drive waveform of FIG. Figure 3 (a)
And (b). In the panel used for the measurement, the electrode width of each of the scan electrode 11 and the sustain electrode 12 was set to 100
μm, the distance dp between the scanning electrode 11 and the sustain electrode 12 was 80 μm, and the height of the partition 9 was 120 μm. The panel was filled with a mixed gas of neon (Ne) and xenon (Xe) at 66.5 kPa, and the partial pressure of Xe was set at 5%, 12% and 20%. Further, the frequency of the driving waveform in the sustain period was set to 15.3 kHz. The light emission luminance was measured with a luminance meter, and the light emission efficiency was obtained from the light emission luminance and power consumption of the panel. 3 (a) and 3 (b), the Xe partial pressure is 5%,
The results at 12% and 20% are shown by solid line a, solid line b and solid line c, respectively. In the conventional plasma display device, as shown in FIG. 8, the luminous efficiency decreases as the sustain voltage increases, but in the plasma display device of the present embodiment, the luminous efficiency increases as the sustain voltage increases. When the sustain voltage is large,
That is, it can be seen that the luminous efficiency is high when the luminance is high. Therefore, a plasma display device with high luminance and high luminous efficiency can be obtained. Also, when the Xe partial pressure is 5
%, The maximum luminous efficiency (the maximum value of the luminous efficiency) is about the same as the maximum luminous efficiency of the conventional plasma display device, but when the partial pressure of Xe is 12% and 20%,
The maximum luminous efficiency is about 1.8 lm / W, and a plasma display device having a much higher luminous efficiency than the conventional one can be obtained. FIGS. 4A and 4B show changes in luminous efficiency and luminance with respect to the Xe partial pressure, respectively. The solid line a and the solid line b show the case of the present embodiment and the case of the conventional plasma display device, respectively. In each case, the luminance and the luminous efficiency when the Xe partial pressure is 5% are set to 1. The luminous efficiency changes depending on the sustain voltage, but FIG. 4A shows the relative maximum luminous efficiency.
The luminance at that time is shown in FIG. As can be seen from FIG. 4, in the plasma display device of the present embodiment, when the Xe partial pressure exceeds 5%, the luminous efficiency is higher than in the case of 5%, and the luminous efficiency is higher than that of the conventional plasma display device. Has become. Similarly, regarding the luminance, the plasma display device of the present embodiment also uses Xe.
When the partial pressure exceeds 5%, it is considerably larger than in the case of 5%. Therefore, according to the present embodiment, when the Xe partial pressure sealed in the panel exceeds 5%, a plasma display device with high luminance and high luminous efficiency can be obtained. Next, a description will be given of a drive margin representing the ease of driving the panel. When when down each sustain voltage, the sustain voltage not emitting discharge cell begins to occur without maintaining discharge is generated to have the image data and the minimum sustain voltage V _n, went up the sustain voltage to the contrary, when a sustain voltage discharge cells in which the sustain discharge is generated emission for no image data begins to occur with the maximum sustaining voltage V _x, the driving margin is given by V _x -V _n, normally as the driving margin is large The driving voltage range is large and driving is easy. When the panel shown in FIG. 2 is used to drive a panel having a partial pressure of Xe of 5% by the conventional driving method,
Minimum sustaining voltage V _n is the 185V maximum sustaining voltage V _x is 2
It was 50V. In contrast, when driving the panel by the driving method of this embodiment, the minimum sustaining voltage V _n is 18
Maximum sustaining voltage V _x is a 5V was 270V. Therefore, by using the driving method of the present embodiment, the driving margin of the panel becomes 85 V, which can be made 20 V larger than the driving margin (65 V) in the case of using the conventional driving method. Has become. Similarly, when the Xe partial pressure is 12% or 20%, by using the driving method of the present embodiment, the driving margin of the panel becomes larger than before and the panel is easily driven. In the above description, the case where the panel of one embodiment of the present invention has the scanning electrodes and the sustaining electrodes composed only of the metal electrodes has been described. However, the scanning composed of the transparent electrodes as shown in FIG. Similar results are obtained for a panel having electrodes and sustain electrodes. That is, there is a region where the luminous efficiency increases with an increase in the sustain voltage. When the Xe partial pressure exceeds 5% and is 12% or 20%, higher luminance and higher luminous efficiency are obtained as compared with the conventional case. . In addition, the driving margin is increased as compared with the related art, which facilitates driving, and the above-described self-discharge does not occur. Therefore, it is possible to obtain a panel with excellent display quality in which the occurrence of uneven brightness is suppressed. Since a large amount of power can be supplied by using a panel having a large electrode width such as a transparent electrode, the panel shown in FIG. 6 has higher luminance than the panel shown in FIG. Further, as shown in FIG. 5, instead of using a transparent electrode, the scan electrode 13 and the sustain electrode 14 are each constituted by a plurality of divided metal electrodes, and the entire electrode width of the scan electrode 13 and the sustain electrode 14 is equivalently reduced. It may be a panel that is wide. The upper limit of the Xe partial pressure may be appropriately set in consideration of the operating conditions of the panel. As described above, according to the plasma display device of the present invention, the scan electrodes and the sustain electrodes of the plasma display panel having the discharge space filled with xenon having a partial pressure exceeding 5% are provided. By applying a pulse of negative polarity during the sustain period, excellent display quality with high luminance and high luminous efficiency can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A to 1C are waveform diagrams showing a sustain voltage waveform and a light emission waveform in a plasma display device according to an embodiment of the present invention. FIG. FIGS. 3 (a) and 3 (b) show characteristics of sustaining voltage dependence of luminous efficiency and luminance when driving the plasma display panel of FIG. 2 by changing the partial pressure of Xe. FIGS. 4 (a) and 4 (b) are characteristic diagrams showing the dependence of luminous efficiency and luminance on the Xe partial pressure when driving the plasma display panel of FIG. 2 in comparison with a conventional one. FIGS. 6A and 6B are cross-sectional views of a conventional plasma display panel according to another embodiment of the present invention. FIGS. 7A and 7B are cross-sectional views of a conventional plasma display panel. Pa FIG. 8 is a waveform diagram showing a sustain voltage waveform and a light emission waveform in a panel. FIG. 8 is a characteristic diagram showing sustain voltage dependence of luminous efficiency when a conventional plasma display panel is driven. FIG. 1 is a waveform diagram showing a sustain voltage waveform and a light emission waveform in a conventional plasma display panel of the related art. DESCRIPTION OF SYMBOLS 1 Discharge space 2 Surface substrate 3 Back substrate 4, 11, 13 Scanning electrodes 5, 12, 14 Protective film 8 Data electrode 9 Partition wall 10 Phosphor layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G09G 3/28 EF term (reference) 5C040 FA01 FA04 GB03 GB14 GJ02 GJ08 LA18 MA03 MA20 5C080 AA05 BB05 DD30 FF12 HH04 HH05 JJ04 JJ05 JJ06

Claims (1)

Claims: 1. A plurality of scanning electrodes and sustaining electrodes are arranged and formed on one of two substrates opposed to each other so as to form a discharge space therebetween, and the discharge space is formed in the discharge space. A plasma display panel configured by enclosing xenon having a partial pressure of more than 5%, and a driving unit for applying a negative pulse to a scan electrode and a sustain electrode of the plasma display panel during a sustain period. Plasma display device.