Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-08-24
2001-10-16
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
Reexamination Certificate
active
06304238
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving apparatus of a liquid crystal display apparatus in which a plasma addressed liquid crystal display apparatus is used.
2. Description of the Related Art
Recently, after an installation space or the like which can be secured at home, for example, is taken into consideration, a large-sized and thin-type television image receiver and a back-projection type projector apparatus have been in common use in order to obtain a more forceful image.
According to technical progress, such a television image receiver and a back-projection type projector apparatus have been thinner compared with the conventional ones. However, there is a limit in their thinning because of structural conditions such as depth of a CRT (Cathode Ray Tube) of the television image receiver and installation angle of a projection lens of the projector apparatus.
In addition, a display device using a TFT (Thin Film Transistor) liquid crystal panel can be thinned further than the above-mentioned television image receiver and the protector apparatus. However, in order to produce a large-sized display apparatus, according to increase in number of TFTs formed by IC technique, more accurate producing technique is required, and the cost becomes very high due to decrease in the yield of production.
Therefore, there has been proposed a display device using a plasma addressed liquid crystal display apparatus (hereinafter, referred to as PALC from its initial), where a screen which is as large as those of the television image receiver and projector apparatus is formed and which is as thin as the TFT liquid crystal panel, as a display section.
Such a plasma addressed liquid crystal display apparatus can realize high luminance and high contrast which are as high as those of the TFT liquid crystal panel, and can realize a large screen by means of producing technique of a PDP (Plasma Display Panel). Moreover, the plasma addressed liquid crystal display apparatus is a normally white (or normally black) plasma addressed liquid crystal display apparatus.
There will be described below a structure of a PALC to be used in embodiments of the present invention, mentioned later, with reference to
FIGS. 2 and 3
.
FIG. 2
is an exploded perspective view of a liquid crystal display apparatus using the PALC.
FIG. 3
is a perspective view showing a part of the structure of the PALC, and shows a cross section of the part. As shown in
FIG. 2
, a PALC
1
has a structure of a transmitting display device where a luminous flux radiated from a back light
2
arranged on a rear surface of the PALC
1
is selectively transmitted by an active-matrix method, and thus an image is formed.
As shown in
FIG. 3
, a plasma substrate (rear glass)
5
is formed with scanning grooves
7
,
7
,
7
, . . . which are partitioned with an uniform interval into a hollow shape in a horizontal direction, for example, (or scanning grooves which are formed by cutting) by partition walls
6
,
6
,
6
, . . . Anode electrodes
8
,
8
,
8
, . . . and cathode electrodes
9
,
9
,
9
, . . . are formed respectively in the scanning grooves
7
with an uniform interval so as to make a pair. Namely, the scanning grooves
7
compose horizontal scanning lines corresponding to an effective screen of the PALC
1
, and the scanning grooves
7
are formed correspondingly to a number of the scanning lines (for example, about 480 lines).
A thin glass substrate
10
forming an insulating layer is provided on the forward side of ribs
6
,
6
,
6
, . . . so that the scanning grooves
7
can be sealed. A noble gas such as a helium gas or a mixed gas of noble gases is charged as a plasma gas into the scanning grooves
7
.
In addition, an about −300 V scanning voltage of a negative polarity pulse, for example, is applied from a driver circuit of plasma discharge, not shown, to the cathode electrodes
9
with a predetermined timing (here, a ground electric potential is given to the anode electrodes
8
), and as detailed later, a plasma discharge takes place between the anode electrodes
8
and the cathode electrodes
9
.
Due to this plasma discharge, the plasma gas is ionized in the scanning grooves
7
, and electrically conductive bodies, namely plasma channels are formed until the plasma particles completely vanish so that a selecting operation (strobe) which is equivalent to that of a switching element is performed.
On the front side of a thin plate glass substrate
10
, a liquid crystal layer
11
for forming an image in a matrix pattern, color filters
12
which are composed of striped red, green and blue filter sections
12
R,
12
G and
12
B corresponding to the colors of red, green and blue, transparent driving electrodes (as one example, ITO (Indium Tin Oxide) thin films)
13
which are composed of striped red, green and blue driving electrodes
13
R,
13
G and
13
B for driving pixels of the liquid crystal layer
11
are arranged with an uniform interval so as to intersect perpendicularly to the scanning grooves
7
,
7
,
7
, . . . Each of the intersected portions becomes each of the pixels.
Namely, an image signal (data) for one horizontal line amount is supplied to the transparent driving electrodes
13
R,
13
G and
13
B of the PALC
1
, and the plasma gases in the scanning grooves
7
are selected (strobe) in a vertical direction successively so as to be discharged. As a result, the image signal is applied to the liquid crystal of the pixels where the transparent driving electrodes
13
R,
13
G and
13
B intersect perpendicularly to the scanning grooves
7
, and transmittance of a light emitted from the back light
2
is different at each of the pixels so that a color image can be displayed.
Namely, as shown in
FIG. 2
, when polarization filters
3
and
4
are arranged respectively on an incident side and an emission side of the PALC
1
, a quantity of transmitted light polarized by the PALC
1
can be controlled. As a result, a color image can be obtained by a principle which is similar to that of a normal TFT liquid crystal display apparatus.
Detailed below is the switching operation for forming an image for
1
field amount with reference to
FIGS. 4 and 5
.
FIG. 4
is a schematic diagram showing a portion of the PALC
1
shown in
FIG. 3
viewed from the side. Here, in order to explain the switching operation by means of plasma channels, for convenience, a switch SW is shown in FIG.
5
A.
As mentioned above, when a plasma generating pulse of −300 V, for example, is applied to the cathode electrodes
9
(a ground electric potential is given to the anode electrodes
8
) so that plasma discharge is caused, plasma channels are formed in the scanning grooves
7
. The plasma channels become virtual electrodes so that an image signal voltage is applied between the transparent driving electrode layers
13
(red, green and blue driving electrodes
13
R,
13
G and
13
B) and the anode electrodes
8
.
FIG. 4
shows a state that when the voltage of −300 V is applied to the cathode electrode
9
by the switch SW, the plasma gas is generated by discharge in the scanning groove
7
on the first line, and the strobe is turned ON. The plasma gas is not yet generated in the scanning groove
7
on the second line, and the strobe is remained OFF. As shown in
FIG. 4
, when the plasma channels are formed by the plasma discharge, the inside of scanning grooves
7
is in a conducting state, and this, as shown in
FIG. 5B
, can be equivalently explained as an operation of an FET (Field-effect Transistor) switching element.
This switching operation by means of the plasma channels generates a virtual electrode on an inner surface of the thin glass (substrate)
10
in FIG.
4
. Here, when an image signal voltage for driving pixels is applied to the transparent driving electrodes
13
R,
13
G and
13
B, a driving voltage is applied to the respective pixels (for 1 line amount) of the liquid crystal layer
11
which become the intersections between the scanning grooves
7
where plasma
Maioli Jay H.
Nguyen Jimmy H.
Shalwala Bipin
Sony Corporation
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