Title: Field emission display having integrated getter arrangement
Abstract: A field emission display (FED) and a manufacturing method thereof are provided. The FED includes a getter portion isolated outwardly from an active display region. This getter portion includes a non-evaporable getter layer for absorbing gas and an electron emission source for activating the getter layer. Accordingly, by activating the non-evaporable getter, the gas generated in the display is easily absorbed, and the FED is maintained in a high vacuum state.
Patent Number: 6,963,165 Issued on 11/08/2005 to Park, et al.
| Inventors:
|
Park; Nam-sin (Kyungki-do, KR);
Jin; Sung-hwan (Seoul, KR);
Lee; Hyun-ji (Kyungki-do, KR)
|
| Assignee:
|
Samsung SDI Co., Ltd. (Suwon, KR)
|
| Appl. No.:
|
353991 |
| Filed:
|
January 30, 2003 |
Foreign Application Priority Data
| Jan 30, 2002[KR] | 2002-5366 |
| Current U.S. Class: |
313/495; 313/493; 313/497; 313/553; 313/558; 313/559 |
| Intern'l Class: |
H01J 007/18; H01J 001/02 |
| Field of Search: |
313/495,493,496,497,553,558,559,309,422
|
References Cited [Referenced By]
U.S. Patent Documents
| 5453659 | Sep., 1995 | Wallace et al.
| |
| 5693438 | Dec., 1997 | Liu et al.
| |
| 5734226 | Mar., 1998 | Cathey.
| |
| 5835991 | Nov., 1998 | Niiyama et al.
| |
| 5849442 | Dec., 1998 | Liu et al.
| |
| 5866978 | Feb., 1999 | Jones et al.
| |
| 5894193 | Apr., 1999 | Amrine et al.
| |
| 6100627 | Aug., 2000 | Carretti et al.
| |
| 6127777 | Oct., 2000 | Watkins et al.
| |
| Foreign Patent Documents |
| 1 020 889 | Jul., 2000 | EP.
| |
| A-2001-210225 | Aug., 2001 | JP.
| |
| WO 99/0082/2 | Jan., 1999 | WO.
| |
Primary Examiner: Guharay; Karabi
Assistant Examiner: Roy; Sikha
Attorney, Agent or Firm: Buchanan Ingersoll PC
Parent Case Text
This application claims the priority from Korean Patent Application No. 2002-5366,
filed on Jan. 30, 2002, in the United States Patent and Trademark Office, the disclosure
of which are incorporated herein in its entirety by reference.
Claims
1. A field emission display (FED) comprising:
a front plate and a back plate spaced from one another by a gap, providing an
active display region in an internal vacuum space formed therebetween;
an electron-emitting portion being provided in the active display region on the
back plate and including a cathode, an electron emission source being formed on
the cathode, and a gate electrode for controlling electron emission;
a light emission-displaying portion corresponding to the electron-emitting portion,
being provided in the active display region on the front plate and including an
anode corresponding to the cathode, and a phosphor layer from which light is emitted
by electrons emitted from the electron-emitting portion; and
a getter portion including a getter anode that is provided inside of the front
plate or the back plate, a getter layer that is formed on the getter anode and
absorbs gas through activation, a getter cathode that is positioned on the back
plate or the front plate to face the getter anode, and a getter electron emission
source that is formed on the getter cathode and emits electrons for activating
the getter layer
wherein a supporter is provided under the getter anode for positioning the getter
anode from the front plate or back plate at a predetermined height.
2. The FED of claim 1, wherein the getter electron emission source for activating
the getter layer is a carbon nanotube (CNT) or a micro tip.
3. The FED of claim 1, wherein the getter anode and the getter cathode have a
striped form that extends in one direction inside of the corresponding front plate
and back plate.
4. The FED of claim 1, wherein the getter portion is isolated outwardly from
the active display region.
5. The FED of claim 1, wherein the getter portion is formed to surround the active
display region.
6. The FED of claim 1, wherein the getter layer is formed of non-evaporable type
zirconium (Zr) particles.
7. The FED of claim 6, wherein the getter layer has a thickness of about 20-100 μm.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a field emission display (FED) and a manufacturing
method thereof, and more particularly, to a field emission display (FED), which
is maintained in a high vacuum state by absorbing gases in a display panel through
the activation of a non-evaporable getter (NEG) layer that is formed on the front
plate of the FED, and a manufacturing method thereof.
2. Description of the Related Art
In a field emission display (FED), several hundreds to thousands of micro tips
or carbon nanotubes (CNTs) per pixel are provided as an electron emission source
on a back plate of FED, and a phosphor layer emitting a light by an electron from
the electron emission source is formed on a front plate of FED. A gap between the
front plate and the back plate of FED is usually about 200 μm to several
mms and the display must be maintained in a high vacuum state so that electrons
are moved without energy loss.
A conventional display using electron emission includes a cathode ray tube (CRT)
in a TV set. Since the internal volume of the CRT is very large, it is comparatively
easy that the CRT is maintained in a vacuum state. However, in the case of the
FED, the internal volume of the display is very small, and thus, it is very difficult
that the FED is maintained in a vacuum state. This is the reason materials generating
gases are relatively widely distributed in the small internal volume of the FED,
and thus, vacuum state of FED may be rapidly deteriorated by the gases that is
generated from the materials. Thus, the FED must be manufactured in a high vacuum
state, and this vacuum state has a great effect on the quality and lifetime of
the FED.
FIG. 1 is a schematic cross-sectional view of a conventional FED, and FIG. 2
is a schematic projected top-view of the conventional FED.
The conventional FED includes a front plate
10 and a back plate
20
that are spaced from one another by a gap. An anode
12 and a cathode
22
having a striped form are formed on the opposite inner surfaces of the front plate
10 and the back plate
20, respectively. A gate insulating layer
24
in which holes
24a are formed, is disposed on the cathode
22.
A gate electrode
26 in which gates
26a corresponding to the
holes
24a are formed, is formed on the gate insulating layer
24.
An electron emission source
28 such as micro tip and carbon nanotube (CNT),
is formed on the surface of the cathode
22 that is exposed at the bottom
of the holes
24a.
A phosphor layer
14 having colors corresponding to pixels are coated on
the anode
12, and a black matrix
16 for improving contrast and color
purity is formed among the phosphor layer
14. A plurality of spacers
18
for maintaining the gap between the front plate
10 and the back plate
20
are positioned between the front plate
10 and the back plate
20,
and a sidewall frame
30 for sealing a display panel is positioned at edges
between the front plate
10 and the back plate
20.
An exhausting path
40 for exhausting an internal gas is formed at one
side
of the back plate
20, and a sealing cap
40a for sealing the
outlet of the exhausting path
40 is formed at the outlet of the exhausting
path
40. A gas path
42 through which the internal gas is flowed into
is positioned at another side of the back plate
20, and a getter container
46 including a getter
44 for absorbing gases is connected to the
end of the gas path
42.
In the FED having the above structure, the getter container
46 is protruded
outwardly from the back plate
20, resulting in an increase in the total
thickness of the panel including the getter container
46. Since the absorption
of gas is made through the gas path
42 having a narrow section area with
very large gas flow resistance, the effective absorption of the gas is difficult.
The large gas flow resistance is caused from the narrow gap between the front plate
10 and the back plate
20 that are maintained at a 200 μm to
several mms of interval as well as from the gas path
42. Due to the increase
in gas flow resistance between the front plate
10 and the back plate
20,
it is very difficult that an internal gas, in particular, a gas far from the gas
path
42, is passed through the gap between the front plate
10 and
the back plate
20 and the gas path
42. Accordingly, the internal
gas cannot be effectively removed, and thereby there is a limitation in increasing
internal vacuum level.
SUMMARY OF THE INVENTION
The present invention provides a field emission display (FED), which is capable
of effectively removing residual internal gas, and a manufacturing method thereof.
The present invention further provides a field emission display (FED) which is
capable of absorbing gas so that internal vacuum can be maintained when an internal
gas is generated during the operation of the FED, and a manufacturing method thereof.
Accordingly, according to an aspect of the present invention, there
is provided an improved field emission display (FED). The FED includes a front
plate and a back plate spaced from one another by a gap, providing an active display
region in an internal vacuum space formed therebetween, an electron-emitting portion
being provided in the active display region on the back plate and including a cathode,
an electron emission source being formed on the cathode, and a gate electrode for
controlling electron emission, a light emission-displaying portion corresponding
to the electron-emitting portion, being provided in the active display region on
the front plate and including an anode corresponding to the cathode, and a phosphor
layer from which light is emitted by electrons emitted from the electron-emitting
portion; and a getter portion including an getter anode that is provided inside
of the front plate or the back plate, a getter layer that is formed on the getter
anode and absorbs gas through activation, a getter cathode that is positioned on
the back plate or the front plate to face the getter anode, and a getter electron
emission source that is formed on the getter cathode and emits electrons for activating
the getter layer.
According to another aspect of the present invention, there is provided
a method for manufacturing a field emission display (FED). The method includes
the steps of (a) preparing a back plate on which a cathode, an electron emission
source and a gate electrode for controlling an electron emission on the cathode
are formed, in a predetermined active display region, (b) preparing a front plate
on which an anode corresponding to the cathode and a phosphor layer from which
light is emitted by electrons emitted from the electron emission source are formed,
(c) sequentially forming a getter anode and a getter layer on an inner surface
of the front plate or the back plate, (d) forming a getter cathode on an inner
surface of the back plate or the front plate to face the getter anode, (e) forming
the electron emission source on the getter cathode, (f) sealing the edges between
the front plate and the back plate, exhausting gas and evacuating a space between
the front plate and the back plate, and (g) activating the getter layer by applying
voltage to the getter anode and the getter cathode so that gases generated in the
space is absorbed.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and advantages of the present invention will become
more apparent by describing in detail a preferred embodiment thereof with reference
to the attached drawings in which:
FIG. 1 is a schematic cross-sectional view of a conventional field emission
display (FED);
FIG. 2 is a schematic projected top view of FIG. 1;
FIG. 3 is a schematic cross-sectional view of a FED according to a preferred
embodiment of the present invention;
FIG. 4 is a schematic projected top view of FIG. 3;
FIG. 5 is a projected top view illustrating a modified example of FIG. 4; and
FIG. 6 is a schematic cross-sectional view of a FED according to another preferred
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail by describing
a preferred embodiment of the invention with reference to the accompanying drawings.
The thickness of layers or regions shown in drawings is exaggerated for clarity.
FIG. 3 is a schematic cross-sectional view of a FED according to a preferred
embodiment of the present invention, and FIG. 4 is a schematic projected top view
of the FED according to the preferred embodiment of the present invention, and
a detailed description of elements that are the same as those of the prior art
will be omitted.
The FED according to the preferred embodiment of the present invention includes
a front plate
110 and a back plate
120 that are spaced from one another
by a gap, an electron-emitting portion that is formed on the back plate
120
in an active display region
170, a light emission-displaying portion that
is formed on the front plate
110, and a getter portion
180 that is
isolated outwardly from the active display region
170. Cathodes
122
having a striped form are formed on the inside of the back plate
120. A
gate insulating layer
124 in which holes
124a are formed,
is disposed on the cathodes
122. A gate electrode
126 having gates
126a corresponding to the holes
124a is formed on the
gate insulating layer
124. Electron emission sources
128 such as
micro tip and carbon nanotube (CNT), are formed on the surface of the cathodes
122 that are exposed at the bottom of the holes
124a.
Anodes
112 having a striped electrode or face electrode are formed
on the inside of the front plate
110. Phosphor layers
114 having
colors corresponding to pixels are coated on the anodes
112, and a black
matrix
116 for improving contrast and color impurity is formed among the
phosphor layers
114.
A plurality of spacers
118 for maintaining the gap between the front plate
110 and the back plate
120 are positioned between the front plate
110 and the back plate
120, and a sidewall frame
130 for sealing
a display panel is positioned at edges between the front plate
110 and the
back plate
120. An exhausting path
140 for exhausting an internal
gas is positioned at one side of the back plate
120, and a sealing cap
140a
for sealing the outlet of the exhausting path
140 is formed outside
the exhausting path
140.
The getter portion
180, which is a feature of the present invention, is
formed as a striped form between the active display region
170 and the sidewall
frame
130. The getter portion
180 includes a supporter
152,
an getter anode
154, and a getter layer
156 forming a getter stack
150 on the inner surface of the front plate
110, a getter cathode
on the inner surface of the back plate
120 to be opposite to the getter
anode
154, and electron emission sources for activating a getter
162,
which are formed on the cathodes
160 and emits an electron for activating
the getter layer
156. The electron emission sources
162 may be formed
of carbon nanotube or micro tip.
The getter layer
156 is formed of non-evaporable type zirconium (Zr) particles,
and an oxide layer is formed on the surface of the getter layer
156. The
getter layer
156 absorbs gas while the oxide layer is stripped from its
surface by the electron emission sources
162.
After the getter anode
154 and the getter layer
156 are formed
on a substrate in order to get a plurality of supporters
152, the substrate
is separated through a dicing process, and thereby the plurality of supporter
152
are acquired. The gap between the getter anode
154 and the getter cathode
160 can be controlled by the height of the supporter
152.
The function of the above structure will be described in detail with reference
to drawings.
Firstly, 1˜3 kV voltage is applied to both ends of the getter anode
154 and the getter cathode
160, then electrons with high energy are
emitted from the electron emission sources
162. The emitted electrons are
collided with the surface of the non-evaporable getter (NEG) layer
156,
and thereby a protection layer, which is an oxide layer that is formed on the surface
of getters is removed. Subsequently, residual gases inside the display are absorbed
by the activated getter layers
156. The activation operation of the getter
layer
156 is performed when the display is manufactured or the luminance
of the display is lowered.
Subsequently, when 1˜3 kV voltage is applied between the cathode
122 and the gate electrode
126, electrons are emitted from the front
edges of the electron emission sources
128 having strong electric fields,
and the emitted electrons are collided at the color phosphor layer
114 on
the front plate
112, and thereby, desired image data is displayed on the FED.
FIG. 5 is a projected top view illustrating a modified example of the FED according
to the present invention, and same reference numerals are used in same elements
as in the preferred embodiment, and a detail description thereof will be omitted.
Referring to FIG. 5, a getter portion
180′ is formed to surround
the active display region
170. Likewise, the getter portion
180′,
which is a feature of the present invention, may be formed in various positions,
and the operation of the getter portion
180′ is as described above,
and thus, a description thereof will be omitted.
The manufacturing process of the FED having the above structure will be described
in detail with reference to drawings.
The anode
112 of face electrode, the phosphor layer
114 having
colors of red (R), green (G), and blue (B), and the black matrix
116 are
formed on a glass plate as the front plate
110, and then, a getter stack
150 is attached outside the active display region
170. The getter
stack
150 includes the supporter
152, a getter anode
154,
and a non-evaporable getter (NEG) layer which are sequentially stacked. And the
getter anode
154 under the getter layer
156 is connected to an external
terminal electrode (not shown) that is formed outside vacuum space with a conductive paste.
To manufacture the getter stack
150, firstly, an indium tin oxide (ITO)
layer which is a transparent conductive film, is coated on a substrate having the
thickness of 400-700 μm to the thickness of 1800-3000 Å as a face
electrode form, by using sputtering equipment. Next, a non-evaporable getter (NEG)
layer of which main composition is zirconium (Zr), is uniformly formed to the thickness
of 20-100 μm on the ITO electrode layer.
Subsequently, the substrate on which the getter layer is formed is
diced to have the length of 5-10 mm, and thereby a plurality of the getter stack
150 is fabricated.
After that, the getter stack
150 is bonded on the front plate
110
by melting a frit between the getter stack
150 and the front plate
110.
The getter layer
156 is formed through a screen printing method using
zirconium (Zr) paste with high viscosity, or is formed by forming zirconium (Zr)
on a plate in a solution state with low viscosity containing electric charge materials
through an electrophoresis method and by attaching the plate on which Zr is formed,
to the getter anode
154.
The zirconium (Zr) paste is acquired as a mixture of a getter material having
a main component of zirconium powder with high purity and binder solution that
is formed of nitrocellulose and acetate as a viscosity-retentive material. In this
case, the zirconium powder is preferably 60-90 weight % in the mixture.
In a case where the getter layer
156 is formed through the screen printing
method, the formed getter layer
156 is dried and sintered at a temperature
of 380-430° C., and organic materials such as solvent and solute that are
contained in the zirconium paste are decomposed, and only getter particles having
a main component of zirconium (Zr) are formed on the getter anode
154. Preferably,
a thermal process of the getter layer
156 is performed in an inactive gas
atmosphere so that a minimum of oxide layer is formed on the surface of the getter material.
Meanwhile, a cathode
122 and a gate insulating layer
124
are formed in regions corresponding to the active display region
170 and
the getter stack
150 on the back plate
120 of a glass substrate.
Next, a gate electrode
126 is formed on the active display region
170,
and a getter cathode
160 is formed on the gate insulating layer
124
corresponding to the getter stack
150.
Next, the gate electrode
126 and the gate insulating layer
124
are etched as a circular hole shape in which electron emission sources
128
are to be formed. The electron emission sources
128 are coated in the hole
in a paste state. In such a case, preferably, the electron emission sources
162
are simultaneously formed on the getter cathode
160.
Next, the sidewall glass
130 is disposed at edges between the back plate
120 and the front plate
110, and a frit paste is deposited in an
area where the sidewall glass
130 contacts the back plate
120 and
the front plate
110, and these are jointed to one another. Subsequently,
the contact area is sealed after the frit paste is thermally melted, and the end
of the gas path
140 is connected to a heating and exhausting apparatus (not
shown), and the heating and exhausting process of the panel is performed so that
the inside of the panel is maintained in a high vacuum state. Various residual
gases that may be generated sometime inside the display panel are emitted by heating
the panel at a temperature of about 320-350° C. and the gases are exhausted
during the heating and exhausting process. After the vacuum state inside the panel
is lower than or equal to 10
-5 torr, a sealing cap
140a is
attached to the end of the gas path
140, or the end of the gas path
140
is melted and sealed.
Next, 1˜5 kV voltage is applied between the getter anode
154 and
the getter cathode, electrons with high energy are emitted from the electron emission
sources
162 and are collided at the surface of the non-evaporable getter
layer
156, and thereby the getters are activated.
In order to drive the FED that is manufactured through the above method, by applying
about 70˜100 V voltage between the cathode
122 and the gate electrode
126, and maintaining about 1˜3 kV of potential difference between
the cathode
122 and the anode
112, electrons emitted from the electron
emission sources
128, are passed through a vacuum region, and are collided
with the phosphor layer
114 on the anode
112, and thereby light is
emitted in a desired portion. Here, the cathode
122 and the gate electrode
126 each have a linear electrode form having a predetermined interval and
width, form an X-Y matrix structure in which the cathode
122 and the gate
electrode
126 face each other and between which the gate insulating layer
124 is placed, and thus, light is emitted only in a selected region.
As described above, the non-evaporable getter is used in the FED according to
the present invention, and thereby, the gas that is generated in the display is
easily absorbed, and the FED is maintained in a high vacuum state.
FIG. 6 is a schematic cross-sectional view of a FED according to another preferred
embodiment of the present invention. The FED arrangement shown in FIG. 6 is similar
to that shown in FIG. 3, except that the getter portion including the getter anode
154 is provided inside of the back plate
120 and the getter cathode
160 is positioned on the front plate
110 to face the getter anode.
As in the arrangement of FIG. 3, the getter layer
156 can be formed on the
getter anode
154 and absorbs gas through activation. The getter electron
emission source
162 that is formed on the getter cathode
160 emits
electrons for activating the getter layer
156. The getter portion shown
in FIG. 6 can be arranged to surround the active display region
170, similar
to the getter portion
180′ shown in FIG.
5. The getter portion
can also be formed in various positions on the front or back plates
110,
120. A detailed description of the elements that are the same as those shown
in FIG.
3 and described above will be omitted.
While this invention has been particularly shown and described with reference
to preferred embodiments thereof, it will be understood by those skilled in the
art that various changes in form and details may be made therein without departing
from the spirit and scope of the invention as defined by the appended claims.
*
