U.S. patent application number 11/354846 was filed with the patent office on 2007-08-16 for method of manufacturing carbon nanotube electron field emitters by dot-matrix sequential electrophoretic deposition.
This patent application is currently assigned to Teco Electric & Machinery Co., Ltd.. Invention is credited to Kuei-Wen Cheng, Chun-Yen Hsiao, Shie-Heng Lee, Yu-An Li, Jin-Lung Tsai.
Application Number | 20070187246 11/354846 |
Document ID | / |
Family ID | 38367216 |
Filed Date | 2007-08-16 |
United States Patent
Application |
20070187246 |
Kind Code |
A1 |
Cheng; Kuei-Wen ; et
al. |
August 16, 2007 |
Method of manufacturing carbon nanotube electron field emitters by
dot-matrix sequential electrophoretic deposition
Abstract
A method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition forms
an electric field for only one pixel in the electrophoretic
deposition, so that only the electrophoretic area has the
electrophoretic effect. Longitudinally aligned cathode electrodes
of a cathode plate include a plurality of electron field
transmitters at the depositing positions, and anode electrodes of
an anode plate perpendicular to the cathode electrodes are
preinstalled, and a switch unit provides a potential difference for
each cathode or anode electrode by a sequential change, and only
one alternating pixel having an electric field between the cathode
and anode plates per unit time of the electrophoresis produces a
deposition effect in the area for manufacturing a carbon nanotube
electron field transmitter, and the sequential voltage change of
each cathode or anode electrode is used to achieve the
electrophoretic deposition effect for all pixels of the cathode
plate.
Inventors: |
Cheng; Kuei-Wen; (Guanyin
Township, TW) ; Tsai; Jin-Lung; (Guanyin Township,
TW) ; Lee; Shie-Heng; (Guanyin Township, TW) ;
Li; Yu-An; (Guanyin Township, TW) ; Hsiao;
Chun-Yen; (Guanyin Township, TW) |
Correspondence
Address: |
HDSL
4331 STEVENS BATTLE LANE
FAIRFAX
VA
22033
US
|
Assignee: |
Teco Electric & Machinery Co.,
Ltd.
|
Family ID: |
38367216 |
Appl. No.: |
11/354846 |
Filed: |
February 16, 2006 |
Current U.S.
Class: |
204/471 |
Current CPC
Class: |
C25B 7/00 20130101 |
Class at
Publication: |
204/471 |
International
Class: |
C25B 7/00 20060101
C25B007/00 |
Claims
1. A method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition,
comprising the steps of: connecting an anode of a power supply to a
plurality of anode electrodes of an anode plate, and connecting a
cathode of the power supply to an input end of a switch unit, and
connecting an output end of the switch unit to a plurality of
cathode electrodes of a cathode plate such that the cathode
electrodes and the anode electrodes are perpendicular with each
other, and connecting a signal generator to an input end of the
plurality of switch units; preparing an electrophoresis solution in
an electrophoresis tank, and placing the cathode plate and the
anode plate which are parallel to each other in the electrophoresis
tank; an anode of a power supply outputting a voltage to the
plurality of anode electrodes of the anode plate, and the signal
generator producing a pulse signal outputted to the plurality of
switch units, such that in the electrophoretic deposition, only one
switch unit is electrically connected, and the rest of the switch
units remain electrically disconnected, and one of the cathode
electrodes of the cathode plate is electrically connected to allow
only one pixel to produce a potential different and have an
electric field between the cathode electrode and the anode
electrode in an electrophoresis period, and the electrically
connected cathode electrode forms a carbon nanotube at a position
for depositing the electron field transmitter; and the electrically
connected switch unit counting the time, while the electrically
connected cathode electrode is going through the electrophoretic
deposition, and once the counted time is up, the electric power
supplied to the cathode electrode will be disconnected to allow the
next switch unit to be electrically connected and the rest of the
switch units remain electrically disconnected, so as to proceed the
electrophoretic deposition for the next cathode electrode
sequentially.
2. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the power supply is a scanning power supply that
supplies a voltage to complete the electrophoresis for a full area
in the period of a cycle, such as completing a full electrophoresis
in a second, and the voltage of a pulse voltage provided by the
anode is equal to 120V.
3. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the anode plate includes a plurality of anode
electrodes disposed transversally on an insulating board.
4. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 3, wherein the insulating board is a glass substrate having
the anode electrode produced on the glass substrate by a process
selected from screen printing and lithography.
5. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the cathode plate includes a plurality of
longitudinally aligned cathode electrodes.
6. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the cathode electrode is a semi-finished product
structure having a finished gate and a manufactured sacrificial
layer.
7. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 6, wherein the sacrificial layer is intended for preventing a
sediment such as a gate or a dielectric layer remained in a region
without going through an electrophoretic deposition.
8. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 6, further comprising the step of removing the film of a
sacrificial layer after the electrophoretic deposition process is
completed.
9. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the cathode plate and the anode plate are parallel
to each other and have an interval of 3 cm to 5 cm, and the cathode
plates and the anode plate are placed in the electrophoresis
tank.
10. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the solution adopts ethanol as a solvent, and the
phosphor powder material for the electron field transmitter of the
electrophoresis employs carbon nanotubes produced by an electric
arc discharge, and its average nanotube length is below 5 .mu.m,
and its average nanotube diameter is below 100 nm, and the carbon
nanotube is a multiwalled carbon nanotube structure with a
concentration in weight percentage equal to 0.1%.about.0.005%.
11. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 10, wherein the concentration in weight percentage is
preferably equal to 0.02%.
12. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the solution further comprises a secondary salt
which is a conducting metal oxide salt formed after the
electrophoresis.
13. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 12, wherein the metal oxide salt is one selected from the
group of indium chloride, indium nitrate, and other salts such as a
tin salt.
14. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 12, wherein the secondary salt is indium chloride with a
concentration in weight percentage equal to 0.1%.about.0.005%, and
a glass powder for increasing adhesiveness with a concentration in
weight percentage greater than 5%.
15. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 14, wherein the secondary salt selects a concentration in
weight percentage preferably equal to 0.01%.
16. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the signal generator produces a continuous square
wave output.
17. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the switch unit is a timer.
18. The method of manufacturing carbon nanotube electron field
emitters by do-matrix sequential electrophoretic deposition of
claim 1, wherein the switch unit comprises a timer and a switch.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a field emission display,
and more particular to an electrophoretic deposition technology for
manufacturing electron field emitters for pixels by dot-matrix
sequential electrophoretic carbon nanotubes.
[0003] 2. Description of Prior Art
[0004] In a field emission display referred by this invention, an
electric field is used for driving a cathode electron emitter to
produce electrons, and the electrons excite phosphors of an anode
plate, such that the phosphors produce photons to emit light. The
field emission display has lightweight and thin features, and the
size of an effective display area can be made according to the
manufacturing process and product requirements. Furthermore, the
field emission displays do not have the viewing angle issue
occurred in the flat panel displays.
[0005] The structure of a prior art triode field emission display
includes an anode plate, a cathode plate, and a spacer installed
between the anode plate and the cathode plate for providing an
interval with a vacuum area between the anode plate and the cathode
plate as a support between the anode plate and the cathode plate.
The anode plate includes an anode substrate, an anode conducting
layer, and a phosphors layer, and the cathode plate includes a
cathode substrate, a cathode conducting layer, an electron field
transmitter layer, a dielectric layer, and a gate layer, wherein
the gate layer provides a potential difference to draw electron
emissions of the electron field transmitter layer, and the high
voltage provided by the anode conducting layer accelerates the
electron beams, so that the electrons have sufficient kinetic
energy to impinge the phosphors layer on the anode plate to excite
the phosphors to emit light. Thus, when the electrons are moving in
the field emission display, it requires a vacuum equipment to
maintain the display at a vacuum level lower than 10 to 5 torrs,
such that the electrons can obtain a good mean free path, while
avoiding contaminations and infections to the electron field
transmitter and phosphors area To provide sufficient energy for
electrons to impinge the phosphors, an appropriate gap is
maintained between the two plates, so that the electrons can have
enough space for their acceleration to impinge the phosphors and
maximize the effect of producing lights.
[0006] The so-called electron field transmitter layer uses carbon
nanotubes as its major components. Since carbon nanotube was
introduced by Sumio Iijima in 1991 (Nature, Vol. 354, p 56 (1991)),
the carbon nanotube has very high electronic characteristics and
thus it is used extensively in various different electronic
components, and the carbon nanotube comes with a high aspect ratio
greater than 500 and a high rigidity with a Young's Modulus greater
than 1000 GPn, and the tip or recession of the carbon nanotube is
exposed at an atomic level. The aforementioned characteristics are
considered ideal for being used as a material for making electron
field transmitters, such as an electron field transmitter used for
a cathode plate of a field emission display. Since carbon nanotubes
have the aforementioned physical properties, therefore they can be
designed for different manufacturing processes such as screen
printing or thin film process and used for patterning electronic
components.
[0007] In the so-called cathode plate manufacturing technology, the
carbon nanotube is used as the material for making electron field
transmitters and is manufactured on the cathode conducting layer,
and the manufacturing method includes a chemical vapor deposition
(CVD) to directly grow carbon nanotubes onto the cathode electrode
layer of each cathode pixel, or uses a photosensitive carbon
nanotube solution to be patterned onto the cathode conducting layer
of each pixel, or coats a carbon nanotube solution accompanied with
a masking process. However, the electron field transmitter
structure of the foregoing triode field emission display adopts
carbon nanotubes which are applied to the cathode electrode
structure of each pixel, and such manufacturing process still has
issues on its manufacturing costs and limitations on its
three-dimensional structure, and more specifically it is difficult
to achieve the evenness for large-size electron field
transmitters.
[0008] Recently, a so-called electrophoretic deposition (EPD)
technology disclosed in U.S. Pat. Publication No. 2003/0102222
prepares an alcohol suspension by employing carbon nanotubes and
uses magnesium, lanthanum, yttrium, or aluminum ion salts as
secondary salts (chargers) to produce the electrophoresis solution,
and connects the cathode electrode with the electrophoresis
solution for the electrophoretic deposition, such that an AD or DC
voltage is supplied to form an electric field in the solution, and
the ions in the secondary salt solution are attached on the carbon
nanotube phosphors. The electrophoretic mobility produced by the
electric field assists depositing the carbon nanotubes onto a
specific electrode, so that the carbon nanotubes can be deposited
and patterned onto the electrode. The aforementioned technology is
called electrophoretic deposition technology, which can deposit
carbon nanotubes onto an electrode layer easily, and also can avoid
the limitation of the cathode structure on the triode field
emission display, and thus this technology can be used extensively
for manufacturing the cathode plate structure.
[0009] Since the prior art electrophoretic deposition can only
deposit carbon nanotubes onto a cathode electrode without
depositing the carbon nanotubes on the gates that will electrically
connect the gates with the cathode electrode, therefore a
sacrificial layer or a protective layer is usually installed
between the gate and the dielectric layer to expose the patterned
cathode electrode area before performing the electrophoretic
deposition, and then the protective layer as well as any
unnecessary carbon nanotubes remained in regions that do not
require carbon nanotubes are removed to avoid improper electrical
connections. Another prior art disclosed in Japan Pat. Publication
No. 2001020093 forms a protrusion at the anode electrode
corresponding to a specific region of the cathode in an
electrophoresis. Since the protrusions form a specific electric
field to the corresponding cathode electrode, the carbon nanotubes
in the solution can be deposited in the specific region and the
deposited carbon nanotubes can be centralized at the specific
electrode layer region. A further prior art disclosed by the
present inventor's previous patent application teaches a simple and
easy way of making patterned electrophoresis anode structure to
effectively centralize the electrophoretic deposition regions of an
anode plate device.
[0010] Although the present electrophoretic deposition method
limits and reduces the electrophoretic deposition area, yet the
prior art also provides a voltage to the cathode plate and the
anode plate to form an electric field, and thus a meticulous
computation or design is required for producing the electric field
to maximize the effective regions, or else a poor applicability for
the high-resolution panels may result. The unit area of the
electrophoresis region so produced will become smaller, and the
point-to-point electric field so produced will be affected by the
electric field in the neighborhood and thus making it difficult to
achieve the expected effect. Although the point-to-point
electrophoretic deposition technology is employed, an electric
field is produced at the same time, so that the electric fields of
adjacent pixels will interfere with each other easily, and the
dot-matrix point-to-point electrophoretic deposition effect can no
longer be maintained.
SUMMARY OF THE INVENTION
[0011] In view of the foregoing shortcomings of the prior art, the
inventor of the present invention based on years of experience in
the related industry to conduct experiments and modifications, and
finally invented a method of manufacturing carbon nanotube electron
field emitters by do-matrix sequential electrophoretic
deposition
[0012] Therefore, the present invention is to provide an
alternating electrophoretic deposition technology to improve the
electrophoretic deposition effect on the regions of a dot-matrix
structure, so that the electrophoresis time can be focused on the
electrophoretic deposition of a pixel only to centralize the
electrophoretic deposition region and simplify the design of the
anode plate and the electric field produced by the electrophoresis.
The invention enhances the current density used for the
electrophoresis and greatly lowers the equipment cost and reduces
the power consumption for manufacturing large panels, and the
present invention also improves the operating safety.
[0013] Accordingly, a method of manufacturing carbon nanotube
electron field emitters by do-matrix sequential electrophoretic
deposition according to the invention comprises the following
steps:
[0014] An anode of a power supply is connected to a plurality of
anode electrodes of an anode plate and a cathode of a power supply
is connected to a switch unit, and the switch unit is connected to
a plurality of cathode electrodes of a cathode plate, and the
plurality of cathode electrodes and the plurality of anode
electrodes are perpendicular to each other, and a signal generator
is connected to an input end of the plurality of switch units, and
the cathode plate and the anode plate are parallel with each other
and placed in an electrophoresis tank.
[0015] The anode of the power supply outputs a voltage to the
plurality of anode electrodes of the anode plate, and the signal
generator produces a pulse signal outputted to the plurality of
switch units. During the electrophoretic deposition process, only
one switch unit is electrically connected, and the rest of the
switch units is electrically disconnected, and the electrically
connected switch unit applies a pulse signal produced by the signal
generator to a cathode electrode of the cathode plate, such that
the cathode electrode is electrically connected, and only one pixel
forms a potential different with an electric field between the
electrically connected cathode electrode and anode electrode, and
the cathode electrode forms carbon nanotubes disposed at positions
for depositing an electron field transmitter.
[0016] When one of the electrically connected cathode electrodes of
the cathode plate goes through the electrophoresis process, the
electrically connected switch unit counts the time, so that if the
time counted by the switch unit is up, the electric power supplied
to the cathode electrode will be disconnected to allow the next
switch unit to be connected electrically and the rest of the switch
unit will remain disconnected, and such sequence will apply to the
next cathode electrode for continuing the electrophoretic
deposition process.
BRIEF DESCRIPTION OF DRAWINGS
[0017] The features of the invention believed to be novel are set
forth with particularity in the appended claims. The invention
itself however may be best understood by reference to the following
detailed description of the invention, which describes certain
exemplary embodiments of the invention, taken in conjunction with
the accompanying drawings in which:
[0018] FIG. 1 is a schematic view of a cathode plate and an anode
plate of the present invention;
[0019] FIG. 2 is a schematic view of connecting a cathode plate and
an anode plate to an electrophoresis equipment according to the
present invention;
[0020] FIG. 3 is a schematic view of a cathode plate and an anode
plate in an electrophoresis process according to the present
invention;
[0021] FIG. 4 is a schematic view of connecting a cathode plate and
an anode plate to an electrophoresis equipment in a simple and easy
way according to the present invention; and
[0022] FIG. 5 is a schematic view of cathode plate and an anode
plate in another electrophoresis process according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The technical characteristics, features and advantages of
the present invention will become apparent in the following
detailed description of the preferred embodiments with reference to
the accompanying drawings.
[0024] Referring to FIGS. 1 and 2 for the schematic views of a
cathode plate and an anode plate, and connecting the cathode plate
and the anode plate to an electrophoresis equipment according to
the present invention respectively, a method of manufacturing
carbon nanotube electron field emitters by do-matrix sequential
electrophoretic deposition of the invention mainly uses an
alternating scan electrophoretic deposition technology to alternate
the current distribution to the pixels at different regions of the
cathode electrode to produce a carbon nanotube electron field
transmitter on the cathode plate, and such scan method can
effectively lower the peak of the current and also can apply a
pulse signal for manufacturing large panels.
[0025] In the manufacturing method, a cathode plate 1 is prepared
first, and the cathode plate 1 has a or 32 pieces of longitudinally
aligned cathode electrodes 11, and the plurality of cathode
electrodes 11 are semi-finished structures with a finished gate and
a manufactured sacrificial layer, and the sacrificial layer is
intended for preventing sediments (such as gates and dielectric
layers) remained on the regions without going through the
electrophoretic deposition, and the film of the sacrificial layer
is removed after the electrophoretic deposition process is
completed, and a semi-finished substrate of the cathode plate 1
provides a.times.b or 32.times.32 pixels.
[0026] An anode plate 2 is prepared, and a plurality of anode
electrodes 21 of the anode plate 2 are manufactured and disposed
transversally on an insulating board and perpendicular to the
plurality of cathode electrodes 11, and correspond to the pixels of
b or 32 pieces of anode electrodes 21 provided by the cathode plate
2, wherein the insulating board could be a glass substrate having a
plurality of anode electrodes 21 produced on the glass substrate by
screen printing or lithography.
[0027] The plurality of anodes 31 of the scanning power supply 3
are connected to the plurality of anode electrodes 21 of the anode
plate 2 for providing a pulse voltage to each anode electrode 21
sequentially, and the cathode 32 is connected to the input end of
the plurality of switch units 4, and the output end of the switch
unit 4 is connected to the plurality of cathode electrodes 11 of
the cathode plate 1.
[0028] The aforementioned switch unit 4 is selected from either a
timer or a timer operating with a switch, and the switch unit 4 has
a timing function and its path can be set to be electrically
connected or disconnected, and another input end of the switch unit
4 is connected to the output end of the signal generator 5 to
complete the connections by the electrophoretic deposition, wherein
the scanning power supply 3 provides a pulse voltage with a lag to
each anode electrode 21 sequentially.
[0029] Referring to FIGS. 3 and 4 for the schematic views of
connecting a cathode plate and an anode plate in an electrophoresis
process and connecting a cathode and an anode plate with an
electrophoresis equipment in a simple and easy way according to the
present invention respectively, the cathode plate 1, anode plate 2,
scanning power supply 3, switch unit 4, and signal generator 5 are
connected, and then an electrophoresis solution in the
electrophoresis tank 6 is prepared, and ethanol is used as a
solvent, and the phosphors powder of the electron field transmitter
of the electrophoresis adopts carbon nanotubes manufactured by an
electric arc discharge, and the average nanotube length is below 5
.mu.m, and the average nanotube diameter is below 100 nm. The
carbon nanotube has a multiwalled carbon nanotube structure, and
its concentration in weight percentage is 0.1%.about.0.005% (and
preferably 0.02%) and the secondary salts produced after the
electrophoresis adopt the conducting metallic oxide salts including
indium chloride, indium nitrate, or other salts such as tin salts,
and the concentration in weight percentage of indium chloride is
0.1%.about.0.005% (and preferably 0.01%), and the concentration in
weight percentage of a glass powder for improving adhesiveness is
at least 5%.
[0030] The gap between the cathode plate 1 and the corresponding
anode plate 2 is maintained at an interval of 3.about.5 cm and
placed in the electrophoresis tank 6, wherein the voltage of the
scanning power supply 3 is supplied to complete a whole-area
electrophoresis per cycle (such as a whole electrophoresis per
second), and the scanning power supply 3 supplies a voltage to each
of the plurality of anode electrodes 21 with a lag sequentially,
and scans with a frequency b or 32 of each anode with a lag
sequentially and each anode has a Duty=1/b or 1/32 of the positive
pulse voltage 120V supplied to the plurality of anode electrodes
21a of the anode plate 2, and the signal generator 5 produces
continuous square wave signals outputted to a plurality of switch
units 4. By then, the first switch unit 4 is electrically
connected, and the rest of the switch units 4 are electrically
disconnected. The electrically connected switch unit 4 drives the
signal generator 5 to generate square wave signals applied to the
first cathode electrode 11. By then, the first cathode electrode 11
is electrically connected, and thus a potential difference of only
one pixel of the first cathode electrode 11 and first anode
electrode 21 is formed to produce an electric field signal during
the electrophoresis period, so that a carbon nanotube is formed at
a position for the cathode electrode 11 to deposit the electron
field transmitter. During the electrophoretic deposition process,
the first switch unit 4 counts the time synchronously. Once the
time counted by a first switch unit is up, the switch unit 4 will
stop timing, and will disconnect the electric power supplied to the
first cathode electrode 11, so that the second switch unit 4 will
be electrically connected and the rest of the switch units 4 will
remain electrically disconnected. Such sequence will apply to the
next cathode electrode 11 for continuing the electrophoretic
deposition process, so as to complete the manufacture of the
electron field transmitters of the cathode electrode 11. Each of
the foregoing cathode electrodes 11 has a sequential change (or a
higher frequency multiplication) with Duty= 1/32 or 1/a and
sequentially scans with a lag for each cathode electrode 11 with a
frequency equal to a or 32, and thus each pixel is scanned to
perform an electrophoretic deposition with a frequency of a.times.b
or 32.times.32 or its frequency multiplication, and the time for
the electrophoresis counted by the switch unit 4 is set to 15
minutes, and each electrophoresis can produce an electron field
transmitter structure with an even thickness of approximately
5.about.10 um.
[0031] Referring to FIG. 5 for another schematic view of an
electrophoresis process for manufacturing a cathode plate and an
anode plate according to the present invention, the cathode plate
1a according to this embodiment includes a plurality of cathode
electrode 11a, and the anode plate 2a includes a plurality of anode
electrodes 21a, and the anode 31a of the scanning power supply 3a a
is connected to a plurality of anode electrodes 21a of the anode
plate 2a for supplying a pulse voltage to each anode electrode 21a
sequentially, and the cathode 32a is connected to an input end of
the switch unit 4a, and the output end of the switch unit 4a is
connected to a plurality of cathode electrodes 11a on the cathode
plate 1a, and a signal generator 5a is connected to an input end of
the switch unit 4a, and the foregoing switch unit 4a is comprised
of a timer 41a and a switch 42a.
[0032] The plurality of cathode electrodes 11a and anode electrodes
21a are perpendicular to each other and keep an interval of
3.about.5 cm in between and these electrodes 1a, 21a are placed in
the electrophoresis tank 6a. The scanning power supply 3a supplies
electric power to each anode electrode 21a with a lag sequentially
and scans each anode electrode 21a with a lag. The scanning power
supply 3a provides a positive pulse voltage equal to 120V. By then,
the signal generator 5a produces a signal outputted to the
plurality of switch units 4a, wherein only the first switch unit 4a
is electrically connected, and the rest of the switch units 4a
remained electrically disconnected. Therefore, only one pixel forms
a potential difference to produce an electric field between the
first cathode electrode 11a and the first anode electrode 21a
during the period of electrophoresis, so that the first cathode
electrode 11a forms carbon nanotubes disposed at the positions for
depositing an electron field transmitter, while the timer 41a of
the switch unit 4a starts counting time. Once the time counted by
the timer 41a is up, the switch 42a will immediately disconnect the
power supplied to the first cathode electrode 11a, and allow the
second switch unit 4a to be electrically connected and the rest of
the switch units 4a remain electrically disconnected, so as to
perform the electrophoretic deposition process for the next cathode
electrode 11a sequentially, and scan the pixel of the next cathode
electrode 11a sequentially.
[0033] In summation of the description above, the method of
manufacturing carbon nanotube electron field emitters by do-matrix
sequential electrophoretic deposition in accordance with the
present invention has the following advantages:
[0034] 1. The conducting wires on the electrodes of the cathode
plate and the anode plate in the electrophoresis are installed
alternately, so that the time of the electrophoresis focuses on a
pixel for the electrophoretic deposition to centralize the
electrophoretic deposition region.
[0035] 2. The design of the invention provides a simpler and easier
way to simplify the design of the anode plate in an
electrophoresis. Unlike the complicated interactions of electric
fields in the prior art, the electrophoresis process of the
invention is simplified, such that the invention can produce a
simplified electric field for the electrophoresis.
[0036] 3. Since the electrophoresis gives better regions per unit
area, and thus the current density for the electrophoresis is
improved.
[0037] 4. The current for a large-area electrophoresis is large,
and thus the invention can lower the equipment cost, reduce the
power consumption, and improve the operating safety.
[0038] The present invention is illustrated with reference to the
preferred embodiment and not intended to limit the patent scope of
the present invention. Various substitutions and modifications have
suggested in the foregoing description, and other will occur to
those of ordinary skill in the art. Therefore, all such
substitutions and modifications are intended to be embraced within
the scope of the invention as defined in the appended claims.
* * * * *