Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1995-09-01
2001-03-20
Saras, Steven J. (Department: 2775)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S060000, C345S063000, C315S169400
Reexamination Certificate
active
06204833
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display device with a plasma addressed display panel where a display cell and a plasma cell are superimposed via a common dielectric sheet, and more particularly, the present invention relates for a configuration for a driving circuit for a plasma addressed display panel. Additionally the invention relates to a structure for suppressing crosstalk which is dependent on the thickness of a dielectric sheet interposed between the display cell and the plasma cell to separate them from each other.
2. Description of Related Art
There has been proposed a plasma addressed display panel where a plasma cell is utilized for addressing a display cell, and a typical one is disclosed in, e.g., Japanese Patent Laid-open No. Hei 1 (1989)-217396. As shown in
FIG. 9
, this plasma addressed display panel has a stacked structure consisting of a display cell
101
, a plasma cell
102
and a common dielectric sheet
103
interposed therebetween. The plasma cell
102
is comprised of a glass substrate
104
and is joined to the dielectric sheet
103
with a predetermined space kept therebetwen. This space is sealed up with an ionizable gas contained therein. On the inner surface of the glass substrate
104
, there are formed striped discharge electrodes
105
in the direction of rows. The striped discharge electrodes
105
function alternately as anodes and cathodes to generate plasma discharges
106
therebetween. Each pair of the anodes and cathodes constitute a discharge channel. Meanwhile the discharge cell
101
is comprised of a glass substrate
107
. This glass substrate
107
is disposed opposite to the dielectric sheet
103
through a predetermined gap, which is filled with an electro-optical substance such as a liquid crystal
108
. Striped signal electrodes
109
are formed on the inner surface of the glass substrate
107
. The signal electrodes
109
extend in the direction of columns and intersect orthogonally with the row-direction discharge channels, wherein matrix pixels are located at the intersections of the signal electrodes and the discharge channels. In the plasma addressed display panel having such a structure, display driving is performed by line-sequentially switching and scanning the striped discharge channels where plasma discharges
106
are generated and simultaneously applying, in synchronism with the scanning, picture signals to the signal electrodes
109
on the side of the display cell
101
. Upon generation of plasma discharges
106
in the discharge channels, the inside is turned to the anode potential substantially uniformly, and the pixels are selected per row. That is, each discharge channel functions as a sampling switch. When a picture signal is applied to each pixel in an conducting state of the sampling switch, the pixel can be turn on or off under control. And even after the sampling switch is turned to its non-conducting state, the picture signal is still held in the related pixel and thus a sample-and-hold action is performed.
The problems to be solved by the present invention will now be described below with reference to FIG.
9
. In the plasma addressed display panel where a picture signal is written by utilizing a plasma discharge, there occurs crosstalk termed “data diffusion” in the direction orthogonal to the signal electrodes
109
(along the discharge channels) resulting from the thickness of the dielectric sheet
103
which separates the liquid crystal
108
and the discharge channel from each other. This crosstalk called, data diffusion, is caused by the interference between the data of adjacent pixels. This phenomenon results in poor color representation, and in a worse case, in degrading the horizontal resolution. For this reason, the color reproducibility is inferior in such a color display. Hereinafter an explanation will be given on a mechanism of causing such data diffusion. As shown in
FIG. 9A
, a plasma discharge
106
is generated at the time of writing a picture signal in each pixel, and after selection of the pixel, a picture signal supplied to the signal electrode
109
is written in a liquid crystal capacity. Subsequently, as shown in
FIG. 9B
, the plasma discharge is brought to a halt to induce a non-selected state, whereby the picture signal is held. First, when the picture signal is written, a charge pattern corresponding to the picture signal is formed on one side of the dielectric sheet
103
in contact with the plasma discharge
106
. However, since the total thickness of the liquid crystal
108
and the dielectric sheet
103
is so large as to be nonnegligible in comparison with the pixel pitch, the charge pattern thus formed fails to be completely coincident with the shape of the pixel, and consequently the charge pattern is expanded with the data diffusion. During the picture signal holding period (almost the entire period of the actual operation time, e.g., 479/480), as shown in
FIG. 9B
, an electric field is selectively applied to the inside of the liquid crystal
108
by the charge pattern
110
formed on one side of the dielectric sheet
103
which is in contact with the plasma discharge, so that the liquid crystal
108
is driven. As the voltage level of the picture signal during this period is zero volts on average, the electric lines of force at this time are such as illustrated, so that an electric field, which is further expanded than the charge pattern formed at the time of writing the picture signal, is applied to the liquid crystal
108
. Upon the occurrence of such data diffusion, color mixture is caused to induce deterioration of the color reproducibility as a result in case striped color filters are formed for example correspondingly to the striped signal electrodes. Further, there arises another serious problem that the resolution is lowered in a direction orthogonal to the striped signal electrodes.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate, in driving a plasma addressed display panel, such data diffusion derived from the thickness of a dielectric sheet as observed in the prior art.
According to one aspect of the present invention, there is provided a display device which fundamentally comprises a plasma addressed display panel, a plasma driving circuit and a display driving circuit. The plasma addressed display panel has a layered structure consisting of a display cell with signal electrodes arrayed in columns, a plasma cell with discharge channels arrayed in rows, and a common dielectric sheet interposed therebetween. The plasma driving circuit sequentially drives the discharge channels to thereby address the display cell line-sequentially via the dielectric sheet. Meanwhile the display driving circuit supplies picture signals to the signal electrodes in synchronism with the line-sequential addressing and writes the picture signals in the pixels prescribed at the intersections of the signal electrodes and the discharge channels, thereby displaying a picture. The display device further comprises, as another requisite thereof, a correcting circuit for previously processing the picture signals through a corrective arithmetic operation and then supplying the corrected picture signals to the display driving circuit, hence canceling the data diffusion or crosstalk caused between adjacent pixels due to the thickness of the dielectric sheet. For example, the correcting circuit performs a corrective arithmetic operation with regard to the picture signals supplied to three adjacent signal electrodes to which three primary colors are allocated respectively. In this case, prior to such corrective arithmetic operation, the correcting circuit matches the phases of the picture signals by executing a process of relative delay to the picture signals supplied to the three signal electrodes. Practically, it is preferred that the correcting circuit converts, in advance of the above corrective arithmetic operation, external input primary picture signals into secondary picture signals in ac
Hayashi Masatake
Kichimi Tomoaki
Awad Amr
Saras Steven J.
Sonnenschein Nath & Rosenthal
Sony Corporation
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