Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
1999-07-20
2002-12-17
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169100, C313S552000
Reexamination Certificate
active
06495965
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a cold cathode electronic device, and a field emission luminous device and a cold cathode luminous device each including such a cold cathode electronic device. More particularly, the present invention relates to a cold cathode electronic device which includes a cathode electrode, a gate electrode and an anode electrode and is constructed so as to permit electrons field-emitted from the cathode electrode to reach to at least one of the gate electrode and anode electrode, and a field-emission luminous device and a cold cathode luminous device each including such a cold cathode electronic device, wherein cold cathode is improved in emission characteristics and a phosphor is stabilized in luminous efficiency.
When an electric field set to be about 10
9
(V/m) is applied to a surface of a metal material or that of a semiconductor material, a tunnel effect occurs to permit electrons to pass through a barrier, resulting in the electrons being discharged to a vacuum even at a normal temperature. Such a phenomenon is referred to as “field emission” and a cathode constructed so as to emit electrons based on such a principle is referred to as “field emission cathode (FEC)”.
Recently, development of semiconductor fine-processing techniques permits a field emission cathode of the surface emission type to be constructed of field emission cathode elements having a size as small as microns. Various electronic units wherein a number of field-emission cathodes are arranged in a matrix-like manner on a substrate each function to impinge electrons selectively emitted from emitters on a phosphor, to thereby permit the phosphor to selectively emit light, resulting in being used as an electron feed means for a flat-type display device.
Now, such a conventional field emission display (FED) will be described with reference to FIG.
12
. The field emission display is called a Spindt-type display device.
An FEC of the Spindt type includes a first substrate or cathode substrate
100
, which is then formed thereon with a cathode electrode
101
. The cathode electrode
101
is then formed thereon with a resistive layer
102
, an insulating layer
103
and a gate electrode
104
in order in an upward direction. The gate electrode
104
and insulating layer
103
are formed with holes in common to each other in a manner to extend therethrough, in each of which an emitter electrode
115
of a conical shape in vertical section is provided while being placed on the resistive layer
102
. The emitter electrodes
115
each are arranged in the hole while being exposed at an acute distal thereof through the hole.
Use of fine processing techniques for manufacturing of such an FEC permits a distance between the conical emitters
115
and the gate electrode
104
to be reduced to a level lower than a micron, so that mere application of a voltage as low as about tens of volts permits the emitter electrodes
115
to emit electrodes as desired.
Above the first substrate
100
on which a number of such FECs are arranged in an array is provided a second substrate or an anode substrate
116
constituting an anode electrode in a manner to be opposite thereto. The first substrate
100
and second substrate
116
cooperate with each other, as well as a side plate to form an airtight envelope, which is evacuated to form a vacuum or reduced pressure therein, resulting in the FED being provided.
In the FED thus constructed, a gate voltage Vg is applied between the gate electrode and the cathode electrode and an anode voltage VA is applied between the cathode electrode and the anode electrode, so that electrons emitted from the emitter electrodes
115
may be impinged on a required portion of the phosphor on the anode substrate
116
, resulting in desired luminous display being provided.
FIG. 13
shows a drive unit for driving a color FED in which such an FEC of the surface emission type as described above is incorporated. The FED designated at reference numeral
151
in
FIG. 13
is constructed into an FED panel structure having m×n dots. Reference numeral
152
designates an image signal (image data) inputted,
153
is a signal input buffer, and
154
is a controller for generally controlling the whole panel.
The controller
154
functions to permit the image data inputted thereto through the signal input buffer
153
to be temporarily stored in a display RAM
155
, for example, for each of the three primary colors red, green and blue (RGB) in each frame unit. Also, the controller
154
acts to transfer the thus-stored RGB image data to data drivers (cathode drivers)
156
A and
156
B depending on a display system.
The data drivers
156
A and
156
B output, to cathode terminals Cl to Cm, a cathode voltage Vcc inputted thereto from a cathode power supply
160
B of a power supply
160
and a data pulse subjected to pulse modulation depending on a gradation of the RGB image data from the controller
154
.
In this instance, the power supply
160
, as described above, includes the cathode power supply
160
B for applying the cathode voltage Vcc to the data drivers
156
A and
156
B, as well as a gate power supply
160
A for applying a gate voltage Vgg of a predetermined level to a gate voltage control circuit
159
.
Reference numeral
158
designates an anode power supply/anode switch circuit
158
, which functions to apply an anode voltage of a predetermined level to anode terminals A
1
and A
2
of the FED panel
151
according to control
154
by the controller.
The gate voltage control circuit
159
has an operation order of gate terminals G
1
, G
2
, . . . of the FED panel
151
and timings thereof set therein and functions to feed a pulse voltage of a predetermined level to a scan driver (gate driver)
157
depending on the gate voltage Vgg from the gate power supply
160
A.
The scan driver
157
is fed with a scan signal for scanning each of the gate terminals G
1
, G
2
, . . . of the FED panel
151
from the gate voltage control circuit
159
according to control by the controller
154
. The scan driver
157
functions to drive each of picture cells arranged on the matrix according to a so-called linear sequential system for sequentially selecting the gate terminals G
1
, G
2
, . . . , depending on a display system.
In
FIG. 13
, cathode data of the data drivers
156
A and
156
B and a voltage level of the gate drive signal from the gate voltage control circuit
159
are appropriately set depending on the cathode voltage Vcc outputted from the power supply
160
, so that a dynamic range of luminance in a display section may be adjusted.
As described above, the conventional field emission display (FED) is so constructed that the field emission cathode and the anode conductor provided thereon with the phosphor layer are arranged opposite to each other in the airtight envelope.
More specifically, in manufacturing of the conventional FED, the cathode conductor is formed on an inner surface of the cathode substrate constituting a part of the airtight envelope and then the insulating layer is formed on the cathode conductor, followed by formation of the gate on the insulating layer. Then, the holes are formed through the gate and insulating layer and then the emitter electrodes each are formed in each of the holes while being arranged on the cathode conductor, resulting in the FEC being provided. The anode arranged opposite to the FEC thus provided is provided by forming the light-permeable anode conductor on an inner surface of the anode substrate constituting another part of the airtight envelope and then forming the phosphor layer on the anode conductor.
In the FED thus constructed, a voltage of a suitable level is applied to each of the gate and anode conductor while applying a voltage of a predetermined level to the cathode, to thereby permit electrons to be emitted from a distal end of the emitter electrodes. Then, the electrons thus emitted impinge on a desired portion of the phosphor layer of the anode, leading to luminescence of the phosphor, which is externally
Itoh Shigeo
Kogure Yuuich
Tanaka Gentaro
Uchida Yuji
Yamaura Tatsuo
Futaba Corporation
Tran Thuy Vinh
Wong Don
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