Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
1999-01-25
2003-07-29
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S496000, C313S497000, C313S489000, C313S110000
Reexamination Certificate
active
06600261
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P10 019108 filed Jan. 30, 1998 which application is incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
The present invention relates to a display and a plasma light-emitting device used for the display, and particularly to a plasma addressed liquid crystal (PALC) display (hereinafter, referred to simply as “display”) and a plasma light-emitting device suitably used for the display.
As the display of this type, there is known a type shown in FIG.
3
. For the sake of clarity, only one pixel of the display
1
is shown in FIG.
3
.
Referring to
FIG. 3
, the display
1
includes a plasma light-emitting unit
12
. In the plasma light-emitting unit
12
, a first glass substrate
4
is stacked via a first sheet polarizer
3
on a backlight
2
formed of a dispersion type AC-drive type electroluminescence (EL) element. A cathode electrode
5
and an anode electrode
6
connected to a DC power supply
7
and/or an AC power supply
8
are disposed on the first glass substrate
4
at specific positions. An insulating layer
10
made from an insulating material such as glass is fixed on the first glass substrate
4
via O-rings
9
each being made from a rubber material such as Biton. An enclosed space
11
, which is formed by the first glass substrate
4
, O-rings
9
and insulating layer
10
, is filled with an inert gas such as argon at a specific pressure.
In this plasma light-emitting unit
12
, after the backlight
2
is turned on by an external control mean (not shown), specific voltages are applied to the cathode electrode
5
and anode electrode
6
from the DC power supply
7
and/or the AC power supply
8
in such a manner that the cathode electrode
5
comes into a negative potential relative to the anode electrode
6
, to produce discharge, thereby generating plasma
13
in the space
11
. The generation of the plasma
13
is able to produce charged particles (not shown) in the space
11
.
On the insulating layer
10
of the plasma light-emitting unit
12
are sequentially stacked a liquid crystal layer
14
made from liquid crystal of, for example, twisted nematic (TN) type; a color filter layer
15
such as RGB vertical stripe type; an electrode layer
16
, for example, made from a transparent conductive oxide having an electrically low resistance (for example, SnO
2
or ZnO); a second glass substrate
17
; and a second sheet polarizer
18
.
While not shown, potential difference generating means is connected between the electrode layer
16
and the anode electrode
6
within the plasma light-emitting unit
12
in order to generate a potential difference therebetween on the basis of the potential of the anode electrode
6
.
The operation of this display
1
will be described below. A voltage, which is supplied between the electrode layer
16
and the anode electrode
6
from the potential difference generating means, is applied to the liquid crystal layer
14
and the insulating layer
10
by utilizing, as a switching element which is the charged particle produced when the plasma
13
is generated by the plasma light-emitting unit
12
. At this time, by applying the voltage the liquid crystal layer
14
is charged. When the charged particles disappear after an elapse of a specific time since completion of the discharge of the plasma
13
, the inside of the space
11
comes into the insulating state and thereby any voltage is no longer applied to the liquid crystal layer
14
. The liquid crystal layer
14
holds the stored charges until the next discharge occurs.
In this way, the display
1
is able to display an image by performing scanning in line sequence through operation of cutting off transmission light supplied from the backlight
2
or transmitting the light by control of the liquid crystal layer
14
in combination with operation of the first and second sheet polarizers
3
and
18
.
The above display
1
, however, has a problem that the liquid crystal layer
14
is deteriorated by ultraviolet light (not shown) produced when the plasma
13
is generated by the plasma light-emitting unit
12
. Concretely, by the effect of ultraviolet light, rust gradually permeates into the liquid crystal layer
14
, to discolor the liquid crystal layer
14
into yellow, thereby degrading an image displayed on the display
1
.
Another problem of the above display
1
is that the insulating layer
10
formed of a thin film is easily cracked. This makes the handling characteristic poor. To solve this problem, it may be considered to form the insulating layer
10
using a high polymer material (plastic or the like) in place of glass. In this case, however, there occurs an inconvenience that the high polymer material is deteriorated, that is, discolored into yellow by the effect of ultraviolet light produced when the plasma
13
is generated, as described above.
Further, the latter manner using a high polymer material for forming the insulating layer
10
has another disadvantage. That is to say, since the insulating layer
10
made from a high polymer material allows moisture in atmospheric air and an inert gas sealed in the space
11
to excessively pass therethrough, it is difficult to keep the vacuum state constant within the space
11
. As a result, each of the cathode electrode
5
and anode electrode
6
is easily stuck with impurities (for example, moisture in atmospheric air) by sputter generated in discharge, to shorten the service life of the cathode electrode
5
and the anode electrode
6
, thereby degrading the life of light emission by the plasma
13
. Also since the light emission amount of the plasma
13
is changed by the impurities, variation in pressure, and so on, it is difficult to keep a stable light emission state of the plasma
13
and a stable quality of a displayed image.
A further problem of the display
1
mentioned above is that the insulating layer
10
formed of a single thin film is deflected by a stress caused by the negative pressure in the space
11
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a plasma light-emitting device capable of keeping a stable light emission state of plasma and a stable quality of a displayed image, and a display using the plasma light-emitting device.
To achieve the above object, according to an aspect of the present invention, there is provided a plasma light-emitting device including: means for generating plasma; and means, provided on a specific surface of the plasma generating means, for preventing ultraviolet light, produced when the plasma is generated by the plasma generating means, from leaking outside.
Consequently, in this plasma light-emitting device, it is possible to prevent ultraviolet light produced when the plasma is generated, from leaking outside, and hence to keep a stable light emission state of plasma and a stable quality of a displayed image.
According to another aspect of the present invention, there is provided a display including: means for generating plasma; means, provided on a specific surface of the plasma generating means, for preventing ultraviolet light, produced when the plasma is generated by the plasma generating means, from leaking outside; a liquid crystal layer which is made from liquid crystal and is disposed on the ultraviolet light leakage preventive means; an electrode layer which is made from a transparent conductive oxide and is stacked on the liquid crystal layer; and means for generating a potential difference between the plasma generating means and the electrode layer.
In this display, it is possible to prevent ultraviolet light which is produced when the plasma is generated, from leaking outside, hence to keep a stable light emission state of plasma and a stable quality of a displayed image.
REFERENCES:
patent: 4792716 (1988-12-01), Walsh
patent: 5377029 (1994-12-01), Lee et al.
patent: 5808410 (1998-09-01), Pinker et al.
patent: 5910356 (1999-06-01), Ishikawa et al.
patent: 5935717 (1999-08-01), Oishi et al.
pat
Patel Nimeshkumar D.
Santiago Mariceli
Sonnenschein Nath & Rosenthal
Sony Corporation
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