Multiple level printing in a single pass

Details Multiple level printing in a single pass Multiple level printing in a single pass

2002-09-05

2004-05-04

Patel, Vip (Department: 2879)

Electric lamp and discharge devices

With luminescent solid or liquid material

Vacuum-type tube

Reexamination Certificate

active

06731062

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to the field of electronic displays, and, more particularly, field emission display (“FED”) devices.
As technology for producing small, portable electronic devices progresses, so does the need for electronic displays which are small, provide good resolution, and consume small amounts of power in order to provide extended battery operation. Past displays have been constructed based upon cathode ray tube (“CRT”) or liquid crystal display (“LCD”) technology. However, neither of these technologies is perfectly suited to the demands of current electronic devices.
CRT's have excellent display characteristics, such as, color, brightness, contrast and resolution. However, they are also large, bulky and consume power at rates which are incompatible with extended battery operation of current portable computers.
LCD displays consume relatively little power and are small in size. However, by comparison with CRT technology, they provide poor contrast, and only limited ranges of viewing angles are possible. Further, color versions of LCDs also tend to consume power at a rate which is incompatible with extended battery operation.
As a result of the above described deficiencies of CRT and LCD technology, efforts are underway to develop new types of electronic displays for the latest electronic devices. One technology currently being developed is known as “field emission display technology.” The basic construction of a field emission display, or (“FED”) is shown in FIG.
1
. As seen in the figure, a field emission display comprises a face plate
100
with a transparent conductor
102
formed thereon. Phosphor dots
112
are then formed on the transparent conductor
102
. The face plate
100
of the FED is separated from a baseplate
114
by a spacer
104
. The spacers serve to prevent the baseplate from being pushed into contact with the faceplate by atmospheric pressure when the space between the baseplate and the faceplate is evacuated. A plurality of emitters
106
are formed on the baseplate. The emitters
106
are constructed by thin film processes common to the semi-conductor industry. Thousands of emitters
106
are formed on the baseplate
114
to provide a spatially uniform source of electrons.
FIG. 2
shows a basic construction of a typical field emission display device. As shown, there is a substrate
200
formed of a transparent material, for example, glass. On the substrate
200
, there is formed conductors
202
and spacers
204
. When the FED is finally assembled, conductors
202
will form the contact points necessary to connect the FED into an electronic circuit. Spacers
204
provide the required separation between die
206
and substrate
200
. Without spacers
204
, the die
206
would be forced together with substrate
200
by atmospheric pressure when the device is evacuated. Die
206
has surface
208
which has formed thereon the emitters which will emit electrons to form an image on phosphor layer
210
. Also formed on surface
208
of die
206
are a plurality of contact pads
212
which will be connected to conductors
202
to allow operation of the device.
One method for connecting the bond pads on surface
208
to the conductors
202
is a method referred to as “flip chip” bonding. This technique is described with reference to
FIGS. 3 and 4
.
FIG. 3
shows an example of a die
300
suitable for flip chip bonding. In this example, die
300
has contact pads
302
a
-
302
n
for providing electrical connection to emitters
306
. Bonding pads
302
a
-
302
n
have formed thereon conductive “bumps”
304
a
-
304
n
. Bumps
304
a
-
304
n
provide the electrical connection necessary to the corresponding conductors on the spacers as shown in FIG.
4
.
FIG. 4
is a diagram of a substrate
400
having formed thereon a phosphor layer
402
, a spacer
404
and a plurality of conductors
406
a
-
406
n
. Formed on the upper surface of spacer
404
are a plurality of conductors
408
a
-
408
n
for providing electrical connection to bond pads
302
a
-
302
n
by conductive bumps
304
a
-
304
n
(see FIG.
3
). However, it is still necessary to provide electrical communication between conductors
408
a
-
408
n
formed on the spacer and conductors
406
a
-
406
n
formed on the substrate
400
. One method for providing this communication is shown in FIG.
5
.
FIG. 5
is a top view of a substrate
500
having the conductors
506
a
-
506
n
on the spacer
504
electrically connected to the conductors
510
a
-
510
n
on the substrate
500
. As shown in
FIG. 5
, substrate
500
has formed thereon phosphor layer
502
, spacer
504
and conductors
510
a
-
510
n
. Spacer
504
has formed, on an upper surface, conductors
506
a
-
506
n
. Spacer conductors
506
a
-
506
n
are electrically connected to substrate conductors
510
a
-
510
n
by bonding wires
508
a
-
508
n
. However, the connecting scheme shown in
FIG. 5
is undesirable because it requires that additional manufacturing steps be taken to bond each bonding wire
508
a
-
508
n
between the proper conductors on the substrate
500
and the spacer
504
.
There has therefore been a need in the industry for a method and apparatus to connect substrate conductors to spacer conductors without the use of bond wires.
SUMMARY OF THE INVENTION
According to one embodiment of the invention, a process is provided for forming a conductive line between a conductor and a spacer formed on a substrate of a field emission display, the process comprising disposing a screen between the substrate and a distributing member, the screen having an opening which permits the passage of conductive material, and moving the distributing member along the screen to pass the conductive material through the opening and form a conductive line connecting the conductor and the spacer.
According to another embodiment of the invention, an apparatus is provided for forming a conductive line between a conductor and a spacer with the aid of a screen, the conductor and the spacer being formed on a substrate of a field emission display, the screen being disposed between the substrate and a distributing member and having an opening which permits the passage of conductive material. According to an aspect of the invention, the apparatus comprises a control circuit which moves the distributing member along the screen to pass the conductive material through the opening and form a conductive line connecting the conductor and the spacer.


REFERENCES:
patent: 5315312 (1994-05-01), DiSanto et al.
patent: 5361079 (1994-11-01), Yamamoto
patent: 5430329 (1995-07-01), Harada et al.
patent: 5543680 (1996-08-01), Tomihari
patent: 5612256 (1997-03-01), Stansbury
patent: 5760470 (1998-06-01), Stansbury
patent: 5766053 (1998-06-01), Cathey et al.
patent: 5766361 (1998-06-01), Stansbury
patent: 5871807 (1999-02-01), Stansbury
patent: 5910705 (1999-06-01), Cathey et al.
patent: 6172456 (2001-01-01), Cathey et al.

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