Electric lamp and discharge devices – With getter – With contained getter
Reexamination Certificate
2002-06-13
2004-06-22
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With getter
With contained getter
C313S553000, C313S495000, C252S181700
Reexamination Certificate
active
06753647
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition of a getter, and more particularly, to a composition of a getter and a field emission display using the same that is capable of lowering a temperature of an activation.
2. Description of the Background Art
In general, recently, various flat panel displays are being developed to reduce a weight and a volume, the shortcomings of a cathode ray tube (CRT).
The flat panel displays include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel, an electro-luminescence (EL), and the like. In order to improve a display quality, researches are being actively conducted to heighten a luminance, a contrast and a colorimetric purity of the flat panel display.
The FED is classified into a tip type FED in which a high electric field is concentrated on an acuminate emitter to emit electrons by a quantum mechanical tunnel effect, and a metal insulator metal (MIM) FED in which a high electric field is concentrated on a metal having a certain area to emit electrons by the quantum mechanical tunnel effect.
FIG. 1
is a perspective view of a tip type field emission display in accordance with a conventional art, and
FIG. 2
is a sectional view of the tip type FED in accordance with the conventional art.
As shown in
FIGS. 1 and 2
, the FED includes an upper glass substrate
2
on which an anode electrode
4
and a fluorescent material
6
are stacked; and a field emission array
32
formed on the lower glass substrate
8
.
The field emission array
32
includes a cathode electrode
10
and a resistance layer
12
sequentially formed on the lower substrate
8
, a gate insulation layer
14
and an emitter
22
formed on the resistance layer
12
, and a gate electrode
16
formed on the gate insulation layer
14
.
The cathode electrode
10
supplies current to the emitter
22
, and the resistance layer
12
restricts an overcurrent applied to the emitter
2
from the cathode electrode
10
in order to supply a uniform current to the emitter
22
.
The gate insulation layer
14
insulates the cathode electrode
10
and the gate electrode
16
.
The gate electrode
16
is used as a fetch electrode for fetching electrons.
A spacer
40
is installed between the upper glass substrate
2
and the lower glass substrate
8
.
The spacer
40
supports the upper glass substrate
2
and the lower glass substrate
8
so that a high vacuum state can be maintained between the upper glass substrate
2
and the lower glass substrate
8
.
For example, in order to display a picture, a negative polarity (−) cathode voltage is applied to the cathode electrode
10
and a positive polarity (+) anode voltage is applied to the anode electrode
4
. And, a positive polarity (+) gate voltage is applied to the gate electrode
16
.
Thereafter, electron beams
30
emitted from the emitter
22
collide with the fluorescent material
6
of red, green blue colors to excite the fluorescent material (phosphor). At this time, a visible ray of one of red, green and blue colors is luminescent. In this respect, in order to control each pixel, the FED is formed with a matrix structure as shown by the portion ‘A’ of FIG.
1
.
FIG. 3
is a perspective view showing a gate structure of the FED in accordance with the conventional art, that is, a perspective view showing a gate structure formed in the matrix structure.
First, the cathode electrode
10
and the gate electrode
16
are electrically insulated by the gate insulation layer
14
and formed to cross each other in a horizontal or in a vertical direction.
Gate holes
36
are formed at the gate electrode
16
and emitters
22
corresponding to each gate hole
36
are formed on the cathode electrode
10
.
Thereafter, when the cathode electrode
10
is grounded and some +100V voltage is applied to the gate electrode
16
, a high electric field is generated at the end portions of the emitters
22
positioned at the part where the two electrodes
10
and
16
cross each other, and electrons
30
are emitted by the high electric field.
At this time, the voltage of the gate electrode
16
is lowered down as the size of the gate hole
36
is reduced, and the voltage of the gate electrode
16
differs depending on the characteristics of the material of the emitter
22
. And, by applying a voltage sequentially to the cathode electrodes
10
and the gate electrodes
16
, electrons
30
are emitted from the emitter
22
at the point where the two electrodes
10
and
16
cross each other so that the fluorescent material
6
is excited and accordingly light can be emitted from the pixels.
For example, a high pressure of above a few kV is applied to the anode electrode
4
coated with the fluorescent
6
thereon, in order to accelerate the electrons
30
emitted from the emitter
22
so that the electrons are collide with the fluorescent material
6
.
At this time, as for the luminance of each pixel and color implementation, the luminance of the pixel can be controlled by using a principle that the amount of current differs according to a voltage difference applied between the emitter
22
and the gate electrode
16
and the color can be implemented by controlling the luminance of the three pixels of adjacent red, green and blue.
The electric field emission space inside the panel of the FED should be maintained in a high vacuum state of above 10
−5
Torr in view of its driving characteristics.
That is, the emitter
22
and the gate electrode
16
are separated with a space of about a sub-micron therebetween, into which a high electric field of about 10
7
V/cm is applied.
At this time, unless the space between the emitter
22
and the gate electrode
16
is maintained in the high vacuum state, the voltage between the emitter
22
and the gate electrode
16
may be emitted or an insulator destruction phenomenon may occur.
In addition, unless the electric field emission space is maintained in the high vacuum state, neutral particles existing inside the panel collide with the electrons to generate positive ions.
The generated positive ions collide with the emitter
22
to degrade the emitter
22
or collide with the electrons
30
to reduce an acceleration energy of the electrons
30
to degrade the luminance.
Thus, in order to improve the luminance, a vacuum process is necessary to make inside the panel to be in a high vacuum state during the fabrication process of the FED.
FIG. 4
is a sectional view showing a panel structure of the FED in accordance with the conventional art. That is,
FIG. 4
is to show the getter. Descriptions for constructions repeatedly shown in
FIGS. 1 and 3
are omitted.
As shown in
FIG. 4
, the panel of the FED includes an upper glass substrate
2
on which the anode electrode
4
and the fluorescent material
6
are stacked; a cathode electrode
10
and an insulation layer
14
; a gate electrode
16
formed on the insulation layer
14
; a lower glass substrate
8
with a focussing insulation layer (not shown) formed on the gate electrode
16
; and a glass frit seal
38
supporting the upper glass substrate
2
and the lower glass substrate
8
.
In addition, a getter
34
is formed inside the panel to absorb a gas generated during the FED fabrication process before the upper glass substrate
2
and the lower glass substrate
8
are attached.
The getter
34
is classified into an evaporable getter (EG) and a non-evaporable getter (NEG).
Barium is used as a material of the EG, and the EG is used for a cathode-ray tube forming a television screen and a computer screen. That is, the barium getter is evaporated by an external heating from an inner wall of the cathode-ray tube and used to remove a residual gas inside the cathode-ray tube as a metal film form.
In this respect, barium exists as a precursor of BaAl
4
+Ni before activation, and the activation process is performed when the precursor of barium is evaporated by the external heating.
Substantially, a mixture of powder of the composition BaAl
4
and power of nicke
Fleshner & Kim LLP
Guharay Karabi
LG Electronics Inc.
Patel Nimeshkumar D.
LandOfFree
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