Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-08-31
2003-09-02
Chow, Dennis-Doon (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S066000, C345S067000, C313S484000
Reexamination Certificate
active
06614411
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plasma address display apparatus which includes a flat panel including a display cell and a plasma cell placed one on the other and peripheral circuits, and more particularly to a plasma address display apparatus which has a high resolution of scanning lines formed on a plasma cell.
2. Description of the Related Art
A plasma address display apparatus is disclosed, for example, in Japanese Patent Laid-Open No. Hei 4-265931 and has such a structure as shown in FIG.
1
. Referring to
FIG. 1
, the plasma address display apparatus shown has a flat panel structure which includes a display cell
1
, a plasma cell
2
, and a common intermediate sheet
3
interposed between the display cell
1
and the plasma cell
2
. The intermediate sheet
3
is formed from a very thin glass plate or the like and called microsheet. The plasma cell
2
is formed from a lower side glass substrate
4
adhered to the intermediate sheet
3
, and discharge allowing gas is enclosed in a space defined between the glass substrate
4
and the intermediate sheet
3
. Scanning electrodes in the form of stripes are formed on an inner surface of the lower side glass substrate
4
.
The scanning electrodes function as anodes A and cathodes K. Barriers
7
are formed such that the anodes A and the cathodes K may be sectioned so that an anode A and a cathode K in pair may be included in each section, and divide the space in which the discharge allowing gas is enclosed to define discharge channels
5
in each of which an anode A and a cathode K are included. Each adjacent ones of the discharge channels
5
are isolated from each other by a barrier
7
. The barriers
7
can be formed by printing and baking using screen printing, and contact at the tops thereof with one face of the intermediate sheet
3
. Plasma discharge occurs between an anode A and a cathode K in each discharge channel
5
delimited by a pair of barriers
7
. The intermediate sheet
3
and the lower side glass substrate
4
are adhered to each other by glass frit or the like.
The display cell
1
includes a transparent upper side glass substrate
8
. The glass substrate
8
is adhered to the other face side of the intermediate sheet
3
by a seal member or the like with a predetermined gap left therebetween, and liquid crystal
9
is enclosed as an electro-optical substance in the gap. Signal electrodes Y are formed on an inner surface of the upper side glass substrate
8
. Pixels are formed in a matrix at intersecting locations of the signal electrodes Y and the discharge channels
5
. Also a color filter
13
is provided on the inner surface of the glass substrate
8
, and, for example, three primary colors of R, G and B are allocated to the individual pixels by the color filter
13
. The flat panel having such a construction as described above is of the transmission type, and, for example, the plasma cell
2
is positioned on the light incoming side and the display cell
1
is positioned on the light outgoing side of the flat panel. A backlight
12
is mounted on the plasma cell
2
side.
In the plasma address display apparatus having such a construction as described above, the discharge channels
5
in rows are switchably scanned line-sequentially so that plasma discharge may successively occur therein, and image data is applied to the signal electrodes Y on the display cell
1
side in synchronism with the scanning to effect display driving of the plasma address display apparatus. When plasma discharge occurs in a discharge channel
5
, then the potential in the discharge channel
5
becomes an anode potential substantially uniformly, and pixel selection for each one scanning line is performed.
In particular, one discharge channel
5
corresponds to one scanning line and functions as a sampling switch. If image data is applied to each pixel in a condition wherein the plasma sampling switch is in a conducting state, then sampling of the image data occurs and lighting or extinction of the pixel is controlled with the sampled image data. After the plasma sampling switch is put into a non-conducting state, the image data is held as it is in the pixel. In other words, the display cell
1
modulates incoming light from the backlight
12
into outgoing light in accordance with image data to display an image based on the image data.
FIG. 2
shows two exemplary pixels of the plasma address display apparatus shown in FIG.
1
. Referring to
FIG. 2
, only two signal electrodes Y
1
and Y
2
, one cathode K
1
and one anode A
1
are shown in order to facilitate understanding. Each of the pixels
11
has a layered structure including a signal electrode Y
1
or Y
2
, the liquid crystal
9
, the intermediate sheet
3
and a discharge channel. The discharge channel is connected to the anode potential almost substantially during plasma discharge. When, in this state, image data is applied to each of the signal electrodes Y
1
and Y
2
, then charge is injected into the liquid crystal
9
and the intermediate sheet
3
.
On the other hand, when the plasma discharge comes to an end, then the discharge channel restores an insulating state and comes to have a floating potential, and consequently, the charge injected is held by the pixel
11
. In other words, a sampling holding operation is performed. Since the discharge channel functions as an individual sampling switching element provided for each of the pixels
11
, it is schematically represented using a switching symbol S
1
. In the meantime, the liquid crystal
9
and the intermediate sheet
3
held between each of the signal electrodes Y
1
and Y
2
and the discharge channel function as a sampling capacitor. When the sampling switch S
1
is put into a conducting state by line sequential scanning, the image data is written into the sampling capacitor, and a lighting or extinguishing operation of each pixel is performed in response to the data voltage level. Even after the sampling switch SI is put into a non-conducting state, the data voltage is held by the sampling capacitor. An active matrix operation of the display apparatus is performed in this manner. It is to be noted that an effective voltage to be actually applied to the liquid crystal
9
depends upon a capacitance division between the liquid crystal
9
and the intermediate sheet
3
.
In the plasma address display apparatus having the structure described above, in order to raise the resolution of an image, the density of pixels arranged in rows and columns must be increased. In order to reduce the size of the pixels in the horizontal direction (direction of a row), the line width of the signal electrodes which extend in the direction of a column should be reduced. On the other hand, in order to reduce the size of pixels in the vertical direction (direction of a column), the arrangement pitch of discharge channels which extend in the direction of a row should be reduced.
However, the discharge channels are isolated from each other by the barriers. From a point of view of a working technique, it is difficult to make the thickness of the barriers extremely thin, and a minimum depth is fixed in order to assure a mechanical strength and so forth. Therefore, if the arrangement pitch of the discharge channels is decreased, then a rate in which the thickness of the barriers occupies increases relatively, and therefore, the area of the aperture of the panel through which light actually passes is sacrificed. In other words, as the number of discharge channels, that is, the number of scanning lines, increases, the numerical aperture of the panel decreases. Further, since the barriers have some height dimension, they intercept rays of light coming in from oblique directions. Accordingly, as the arrangement pitch of the barriers decreases, the rate at which incoming rays of light in oblique directions are intercepted increases and the visual angle when the panel is observed by an observer decreases.
When it is tried to increase the resolution of a plasma address display apparatus, a l
Chow Dennis-Doon
Sonnenschein Nath & Rosenthal
Sony Corporation
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