Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
1998-11-20
2001-06-26
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S492000, C445S024000
Reexamination Certificate
active
06252348
ABSTRACT:
TECHNICAL FIELD
The invention pertains to field emission display devices and methods of forming such devices. In a particular aspect, the invention pertains to methods of enhancing intensity of phosphor emissions of field emission display devices.
BACKGROUND OF THE INVENTION
For more than half a century, the cathode ray tube (CRT) has been the principal device for electronically displaying visual information. Although CRTs have been endowed during that period with remarkable display characteristics in the areas of color, brightness, contrast and resolution, they have remained relatively bulky and power hungry. The advent of portable computers has created intense demand for displays which are lightweight, compact, and power efficient. Liquid crystal displays (LCDs) are now used almost universally for lap-top computers. However, contrast is poor in comparison to CRTs, only a limited range of viewing angles is possible, and battery life is still measured in hours rather than days.
As a result of the drawbacks of LCD and CRT technology, field emission display (FED) technology has been receiving increased attention by industry. Flat panel displays utilizing FED technology employ a matrix-addressable array of cold, pointed field emission cathodes in combination with a luminescent phosphor screen. Somewhat analogous to a cathode ray tube, individual field emission structures are sometimes referred to as vacuum microelectronic triodes. Each triode has the following elements: a cathode (emitter tip), a grid (also referred to as the gate), and an anode (typically, the phosphor-coated element to which emitted electrons are directed).
FIG. 1
illustrates a cross-sectional view of a prior art field emission display device
10
. Device
10
comprises a face plate
12
, a base plate
14
, and spacers
26
extending between base plate
14
and face plate
12
to maintain face plate
12
in spaced relation relative to base plate
14
. Face plate
12
, base plate
14
and spacers
26
can comprise, for example, glass. Phosphor regions
16
,
18
and
20
are associated with face plate
12
, and separated from face plate
12
by a transparent conductive layer
22
. Transparent conductive layer
22
can comprise, for example, indium tin oxide or tin oxide. Phosphor regions
16
,
18
and
20
comprise phosphor-containing masses. Each of phosphor regions
16
,
18
and
20
can comprise a different color phosphor. Typically, phosphor regions
16
,
18
and
20
comprise either red, green or blue phosphor. A black matrix material
24
is provided to separate phosphor regions
16
,
18
and
20
from one another.
Base plate
14
has emitter regions
36
,
38
and
40
associated therewith. The emitter regions comprise emitters
42
which are located within radially symmetrical apertures
44
(only some of which are labeled) formed through a conductive gate layer
46
and a lower insulating layer
48
. Emitters
42
are typically about 1 micron high, and are separated from base
14
by a conductive layer
50
. Emitters
42
and apertures
44
are connected with circuitry (not shown) enabling column and row addressing of the emitters
42
and apertures
44
, respectively.
A voltage source
60
is provided to apply a voltage differential between emitters
42
and surrounding gate apertures
46
. Application of such voltage differential causes electron streams
61
,
62
and
63
to be emitted toward phosphor regions
16
,
18
and
20
, respectively. Conductive layer
22
is charged to a potential higher than that applied to gate layer
46
, and thus functions as an anode toward which the emitted electrons accelerate. Once the emitted electrons contact phosphor dots associated with regions
16
,
18
and
20
, light is emitted. As discussed above, the emitters
42
are typically matrix addressable via circuitry. Emitters
42
can thus be selectively activated to display a desired image on the phosphor-coated screen of face plate
12
.
Typical phosphor arrangements associated with a face plate
12
are shown in
FIGS. 2 and 3
. Specifically,
FIGS. 2 and 3
illustrate alternative embodiment face plates
12
, with the face plates having red, green and blue phosphor regions (illustrated as regions labeled “R”, “G”, and “B”, respectively), and black matrix areas
24
surrounding the phosphor regions. Also, the face plates have locations wherein spacers
26
are bound. The face plate of
FIG. 2
corresponds to a display using Sony Trinitron® scanning, and the face plate construction of
FIG. 3
corresponds to a phosphor/black matrix pattern of a conventionally-scanned color display.
The three phosphor colors (red, green, and blue) can be utilized to generate a wide array of screen colors by simultaneously stimulating one or more of the red, green and blue regions. The simultaneous stimulation of multiple regions generates a blend of colors. However, if the color blend is inaccurate, an incorrect color will be displayed. Also, an inaccurate color blend can cause a dirty, non-uniform appearance of a displayed image (a so-called “muddying” of the appearance of a displayed image). Inaccurate color blending can result from, for example, lost illumination efficiency. Illumination efficiency is a measure of the amount of light passed through face plate
12
and toward a viewer relative to the amount of electrons striking a phosphor region. Illumination efficiency is decreased if electrons strike a phosphor region and cause something other than light passing through face plate
12
. For the above-discussed reasons, it would be desirable to develop methods and apparatuses which improve illumination efficiency and enhance blending of primary phosphor colors.
SUMMARY OF THE INVENTION
In one aspect, the invention encompasses a field emission display device. The device comprises a base plate and a face plate which is over and spaced from the base plate. The device further comprises emitters associated with the base plate, and phosphor associated with the face plate. Additionally, the device comprises a reflector associated with the base plate and having an upper reflective surface.
In another aspect, the invention encompasses a method of forming a field emission display device. A base plate is provided, and a pair of spaced emitter-containing regions are provided over the base plate. A reflector is formed over the base plate and between the spaced emitter-containing regions. A face plate is provided, and a pair of spaced phosphor-containing masses are formed in association with the face plate. The face plate and base plate are joined to one another with the face plate being aligned over the base plate and spaced from the base plate. After the joining, the spaced emitter-containing regions align under the spaced phosphor-containing masses, and the reflector aligns under the space between the spaced phosphor-containing masses.
REFERENCES:
patent: 5191217 (1993-03-01), Kane et al.
patent: 5448133 (1995-09-01), Ise
patent: 5866979 (1999-02-01), Cathey, Jr. et al.
patent: 5975975 (1999-11-01), Hofmann et al.
patent: 6020683 (2000-02-01), Cathy, Jr. et al.
Gerike Matthew J.
Micro)n Technology, Inc.
Patel Nimeshkumar D.
Wells, St. John, Roberts Gregory & Matkin P.S.
LandOfFree
Field emission display devices, and methods of forming field... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Field emission display devices, and methods of forming field..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Field emission display devices, and methods of forming field... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2495393