Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-06-08
2003-02-04
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C313S497000, C345S075200
Reexamination Certificate
active
06515429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to flat panel displays (FPDs), and more specifically to field emission displays (FEDs). Even more specifically, the present invention relates to the structural design of field emission displays (FEDs).
2. Discussion of the Related Art
A field emission display (FED) is a low power, flat cathode ray tube type display that uses a matrix-addressed cold cathode to produce light from a screen coated with phosphor materials.
FIG. 1
is a side cut-away view of a conventional FED. The FED
100
includes a cathode plate
102
and an anode plate
104
, which opposes the cathode plate
102
. The cathode plate
102
includes a cathode substrate
106
, a first dielectric layer
108
disposed on the cathode substrate
106
and several emitter wells
110
. Within each emitter well
110
is an electron emitter
112
. Thus, the electron emitters are formed as conical electron emitters, the shape of which aids in the removal of electrons from the tips of the electron emitters
112
. Each electron emitter
112
is generally referred to as a cathode sub-pixel. The cathode plate
102
also includes a gate electrode
114
integral with the cathode substrate
106
and disposed on the first dielectric layer
108
and circumscribing each emitter well
110
. In order to precisely align the gate electrode
114
with the electron emitters
112
, the emitter wells
110
are formed by cutting them out of the first dielectric layer
108
and the gate electrode
114
as formed on the cathode substrate
106
and then placing the electron emitters
112
within the emitter wells
110
. As such, the manufacture of the cathode plate
102
is difficult and expensive.
The anode plate
104
includes a transparent substrate
116
upon which is formed an anode
118
. Various phosphors are formed on the anode
118
and oppose the respective electron emitters
112
, for example, a red phosphor
120
, a green phosphor
122
and a blue phosphor
124
, each phosphor generally referred to as an anode sub-pixel.
The FED
100
operates by selectively applying a voltage potential between cathodes of the cathode substrate
106
and the gate electrode
114
, which causes selective emission from electron emitters
112
. The emitted electrons are accelerated toward and illuminate respective phosphors of the anode
118
by applying a proper potential to a portion of the anode
118
containing the selected phosphor. It is noted that one or more electron emitters may emit electrons at a single phosphor.
Additionally, in order to allow free flow of electrons from the cathode plate
102
to the phosphors and to prevent chemical contamination (e.g., oxidation of the electron emitters), the cathode plate
102
and the anode plate
104
are sealed within a vacuum. As such, depending upon the dimensions of the FED, e.g., structurally rigid spacers (not shown) are positioned between the cathode plate
102
and the anode plate
104
in order to withstand the vacuum pressure over the area of the FED device.
In another conventional FED design illustrated in
FIG. 2
, an FED
200
further includes a second dielectric layer
202
disposed upon the gate electrode
114
and a focusing electrode
204
disposed upon the second dielectric layer
202
. In operation, a potential is also applied to the focusing electrode
204
. This potential is selected to collimate the electron beam emitted from respective electron emitters
112
. Thus, the focusing electrode
204
concentrates the electrons to better illuminate a single phosphor, i.e., the emitted electrons are focused. However, in order to reduce the spread of electrons, a separate focusing structure (i.e., focusing electrode
204
) formed over the gate electrode
114
and that is integral to the cathode substrate
106
is required.
FIG. 3
illustrates a cut-away perspective view of the conventional FED
100
of FIG.
1
. As shown, the gate electrode
114
and the first dielectric layer
108
form a grid in which the generally circular-shaped emitter wells
110
are formed. In fabrication, the first dielectric layer
108
and the gate electrode
114
are formed over the cathode substrate
106
. The emitter wells
110
are formed by etching or cutting out the first dielectric layer
108
and the gate electrode
114
. The conical-shaped electron emitters
112
are then deposited into the emitter well
110
.
Advantageously, the conventional FED provides a relatively thin display device that can achieve CRT-like performance. However, the conventional FED is limited by the pixelation of the device. For example, since there are a fixed number of electron emitters
112
and phosphors aligned therewith, the resolution of the conventional FED is fixed. Furthermore, the manufacture of conventional FEDs has proven difficult and expensive. Additionally, while driving the conventional FED, i.e., applying the proper potential between the gate electrode and the electron emitters
112
, cross-talk is a common problem.
SUMMARY OF THE INVENTION
The present invention advantageously addresses the needs above as well as other needs by providing methods of achieving variable resolution using a field emission display (FED) having a novel structural design.
In one embodiment, the invention can be characterized as a method of achieving a variable resolution on a field emission display and a means for accomplishing the method, the method comprising the step of: addressing a cathode half-pixel region of an emitter line of the field emission display, wherein the emitter line is segmented into a fixed number of cathode sub-pixel regions, each cathode sub-pixel region being defined as a portion of the emitter line between two adjacent gate wires of a plurality of gate wires of a gate frame that pass above the emitter line, wherein the cathode half-pixel region is defined as a portion of the emitter line occupying portions of two adjacent cathode sub-pixel regions, wherein providing the appearance of more than the fixed number of cathode sub-pixel regions.
In another embodiment, the invention can be characterized as a method of achieving a variable resolution on a field emission display and a means for accomplishing the method, the method comprising the step of: addressing at least one cathode half-pixel region of a plurality of emitter lines of the field emission display, wherein each emitter line is segmented into a fixed number of cathode sub-pixel regions, each cathode sub-pixel region being defined as a portion of the emitter line between two adjacent gate wires of a plurality of gate wires of a gate frame that pass above the plurality of emitter lines, wherein each of the at least one cathode half-pixel region is defined as a portion of the emitter line occupying portions of two adjacent cathode sub-pixel regions, wherein providing the appearance of more than the fixed number of cathode sub-pixel regions.
In a further embodiment, the invention may be characterized as a method of achieving a variable resolution on a field emission display comprising the steps of: addressing a cathode half-pixel region of an emitter line of the field emission display, the addressing comprising: applying a positive voltage to a respective gate wire of a plurality of gate wires of a gate frame with respect to the emitter line; and applying a negative voltage to two gate wires adjacent to the respective gate wire with respect to the emitter line, wherein releasing electrons from the cathode half-pixel region of the emitter line; wherein the emitter line is segmented into a fixed number of cathode sub-pixel regions, each cathode sub-pixel region being defined as a portion of the emitter line between two adjacent gate wires of a plurality of gate wires of a gate frame that pass above the emitter line, wherein the cathode half-pixel region is defined as a portion of the emitter line occupying portions of two adjacent cathode sub-pixel regions, wherein providing the appearance of more than the fixed number of cathode sub-pixel regions; and illuminating an
Barger Jack
Russ Benjamin Edward
Fitch Even Tabin & Flannery
Sony Corporation
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