Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-11-19
2004-09-28
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169400, C313S582000
Reexamination Certificate
active
06798144
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flat type plasma discharge display device and its driving method.
2. Description of the Related Art
Hitherto, an alternating-current type display device utilizing a plasma discharge, or a so-called AC (alternating-current) type plasma display panel (PDP) has been known.
This AC type PDP is available in two-electrode constitution and three-electrode constitution.
An ordinary PDP in three-electrode constitution is shown in a perspective exploded view in
FIG. 27
, that is, as shown in this schematic structural diagram in an open state, first and second substrates
51
and
52
each made of, for example, a glass substrate are placed face to face with a specified interval through a partition wall
53
interposed between the two, and their peripheral parts are sealed with glass frit or the like, and a flat type display container is composed.
For example, on the inner surface of the first substrate
51
, there are formed a scanning electrode (first discharge sustaining electrode)
54
serving also as one of the discharge sustaining electrodes and other discharge sustaining electrode (second discharge sustaining electrode)
55
(in
FIG. 27
, only a pair of first and second discharge sustaining electrodes corresponding to one scanning line are shown), and on the inner surface of the second substrate
52
, there is formed an address electrode
56
in a direction intersecting with the scanning electrode
54
and the discharge sustaining electrode
55
.
On the electrode forming surfaces of the both substrates
51
and
52
, dielectric layers
57
are laminated by printing or other means, and a surface protective layer
58
made of MgO or the like is formed further on the surface thereof.
On the second substrate
52
, for example, a fluorescent material
59
for emitting a visible light by ultraviolet rays generated by discharge is coated.
The flat display container formed by the first and second substrates
51
and
52
is filled air-tightly with a gas suited to the discharge.
A driving circuit is connected to each electrode, and a discharge is generated in the space enclosed by the substrates
51
and
52
and the partition wall
53
, and by the ultraviolet rays generated by this discharge, the fluorescent material
59
is excited to emit a light, and a target or intended display is made.
The voltage waveform for driving such a PDP is schematically shown in FIG.
9
. This driving is divided into a “scanning discharge period” for determining a pixel for causing an ordinary discharge, and a “sustained discharge period” for sustaining the discharge of the thus determined pixel.
First, in the scanning discharge period, when scanning the pixel desired to be discharged, a voltage equal to or higher than a discharge start voltage is applied between the scanning electrode
54
and the address electrode
56
at a position corresponding to the pixel. As a result, the pixel at this position is set in discharge start state, and hence the discharge pixel is selected. This selection is made for each one of a plurality of address electrodes for one scanning electrode. That is, the same number of pixels as the number of address electrodes can be driven independently.
Therefore, by scanning a plurality of scanning electrodes sequentially by each scanning line and changing over the voltage of the address electrode
56
every time according to the image desired to be displayed, all pixels for composing one screen can be controlled.
Next, in the sustained discharge period, between the scanning electrode
54
and the discharge sustaining electrode
55
, an AC voltage waveform called a discharge sustaining voltage is applied. At this time, as to the pixel once applied with the voltage equal to or higher than the discharge start voltage in the scanning discharge period, its discharge is sustained thereafter only by application of discharge sustaining voltage, and the luminous display continues. This is a so-called memory effect.
FIG. 9
shows the driving waveform for displaying about one address electrode
56
.
FIG. 9A
shows the display signal waveform applied to this one address electrode
56
, and in this case, for example, the pixels positioned at the intersections with the first, second and fourth horizontal scanning lines are discharged or turned on, and in this case, a specified ON voltage Va is supplied in sections &tgr;
1
, &tgr;
2
, &tgr;
4
.
On the other hand, in each scanning electrode
54
corresponding to each horizontal scanning line, as shown in
FIG. 9B
1
, B
2
, B
3
. . . , to the scanning electrodes
54
adjacent in the vertical direction, a specified ON voltage Vb of reverse polarity to the voltage Va is changed over and applied sequentially in sections &tgr;
1
, &tgr;
2
, &tgr;
3
, &tgr;
4
. . . At this time, to the discharge sustaining electrode
55
making a pair with each scanning electrode
54
, no voltage is applied as shown in FIG.
9
C.
In the next sustained discharge period, in each horizontal scanning line, pulse voltages shown in
FIGS. 9B
1
, B
2
, B
3
. . . and C are applied to the scanning electrodes
54
and the confronting discharge sustaining electrodes
55
.
When such driving waveforms are applied to the respective electrodes, as shown in
FIG. 9D
1
, D
2
, D
3
. . . , in the scanning discharge period, a voltage of Va+Vb is selectively applied in section &tgr;
1
between the scanning electrode
54
and one address electrode
56
in the first horizontal scanning line, in section &tgr;
2
between the scanning electrode
54
and one address electrode
56
in the second horizontal scanning line, and, although not shown, in section &tgr;
4
between the scanning electrode
54
and one address electrode
56
in the fourth horizontal scanning line.
At this time, by preliminarily selecting the Va+Vb equal to or higher than the aforesaid discharge start voltage, and selecting the individual voltages Va and Vb at a voltage not reaching the discharge start voltage, the discharge start state, that is, the ON state is established only for the pixels at the intersection with the address electrode
54
in the selected first, second and fourth horizontal scanning lines.
The pixels once turned on are kept in discharge state in the subsequent sustained discharge period as the desired AC voltage shown in
FIG. 9E
is applied sequentially between each scanning electrode and the discharge sustaining electrode.
Thus, discharge, that is, luminescence about the entire screen, that is, all pixels can be controlled by display signals, and the target or intended image can be displayed.
In the display devices recently advanced remarkably, such as a personal computer, an office work station, a wall-hang television receiver, a large-screen television receiver or the like, there is an increasing demand for higher definition, higher luminance and lower power consumption. In the trend of larger screen, at the same time, there are problems in power consumption and response due to increase in the electrode resistance.
In order to solve such problems, the present applicant formerly proposed a flat type plasma discharge display device, for example, in Japanese Patent Application No. 10-32974 and Japanese Patent Application No. 10-37546.
In these proposed display devices, it is possible to narrow the interval between a pair of discharge sustaining electrodes for discharge sustaining or the interval between the discharge sustaining electrode and a discharge start address electrode, so that the discharge mode may be substantially realized by a cathode glow discharge. Thus, by narrowing the interval between the electrodes, a higher definition is realized, and it is further possible to improve characteristics of cathode glow discharge, such as higher luminance and lower power consumption.
In the display device disclosed in Japanese Patent Application No. 10-32974 and Japanese Patent Application No. 10-37546 mentioned above, by arranging and forming the discharge sustaining electrode group and the address electr
Abe Hironobu
Mori Hiroshi
Rader & Fishman & Grauer, PLLC
Sony Corporation
Vu Jimmy T.
Wong Don
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