Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
1999-12-29
2001-10-23
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C345S074100, C313S495000
Reexamination Certificate
active
06307323
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a field emission display. More particularly, the present invention relates to a field emission display in which field emission devices are applied to the flat panel display.
BACKGROUND OF THE INVENTION
Conventionally, a field emission display is manufactured by vacuum-packaging a lower plate and an upper plate in parallel. The space between the lower plate and the upper plate is within 2 mm. The lower plate includes field emission devices and the upper plate includes phosphors. Electrons are emitted from the field emission devices of the lower plate and the electrons are collided against the phosphors of the upper plate. Right at this time, cathode luminescence effect happens and an image is displayed. Recently, many studies have been performed regarding such field emission displays as a promising flat panel display, replacing conventional cathode ray tube displays.
The key component of field emission display devices is the field emitter and the electron emission efficiency of the field emitter depends upon the structure of the device, the material of the emitter, and the shape of the emitter. The structure of the field emitter can be categorized into diode type and triode type. The diode type includes a cathode and an anode. The triode type includes a cathode, a gate, and an anode. Materials such as metal, silicon, diamond, diamond-like carbon, and carbon nanotube are used as the material of the emitter. Generally, metal or silicon is used to manufacture the triode type and the diamond or carbon nanotube is used for the diode type.
Even though the diode-type field emitters are handicapped by controllability of electron emission and low voltage operation, they are advantageous in some ways. For example, the manufacturing process of the diode-type field emitters is simpler and the reliability of electron emission is higher than the one of the triode-type field emitters.
FIG. 1
shows a diagram illustrating the structure of a conventional field emission display with diode-type field emitters.
Conventional field emission display with diode-type field emitters includes a lower plate
13
with field emitter material and an upper plate
16
. The lower plate
13
includes metal electrodes
11
and field emitter material
12
that is filmed on top of the metal electrodes
11
. The upper plate
16
includes transparent electrodes
14
and red, green, and blue phosphor
15
. With the help of spacer
17
, the lower plate
13
and the upper plate
16
are placed in parallel and vacuum-packaged.
In
FIG. 1
, the metal electrode
11
and the transparent electrode
14
work as a cathode and an anode of field emission devices, respectively. The metal electrode
11
and the transparent electrode
14
are crossed and the crossing section is defined as a pixel.
The conventional field emission display with diode-type field emitters operates as follows.
As shown in
FIG. 2
, the row signal bus
21
R is connected with film-type field emitters
22
in the lower plate
13
. Also, as shown in
FIG. 3
, the column signal bus
31
C is connected with the phosphors
32
in the upper plate
16
. The row signal bus
21
R and the column signal bus
31
C can be varied on the basis of the direction of arrangement of the upper plate
16
and the lower plate
13
.
The display can be driven in a matrix addressing. The row signal bus
21
R selects a row and then the column signal bus
21
C carries display signals into the pixels of the selected row. Then, the next row is addressed in the same way, sequentially.
The electric field necessary for the electron emission is determined by a voltage difference between the column signal bus
31
C and the row signal bus
21
R. When an electric field higher than 1V/&mgr;m is leaded to the field emitter material, electron emissions at the field emitter begin.
Unlike cone-shaped triode-type field emitters, diode-type field emitters don't employ insulation film between the gate and the cathode, and therefore the structure and the manufacturing process is simple. In addition, the reliability of the diode-type field emitters is high because the destruction rate of field emitters is very low when electrons are emitted. The destruction of the gate or the gate insulator, which commonly occurs in triode field emitters, rarely occurs in diode-type field emitters.
However, since high voltages have to be loaded at each electrode of the upper plate
16
and the lower plate
13
(the metal electrode of the lower plate
13
and the transparent electrode of the upper plate
16
) in field emission displays with diode-type field emitters, high voltage display signals are needed and therefore expensive high-voltage operation circuits are also required. Generally, the space between the electrodes of the upper plate
16
and the lower plate
13
is larger than 200 &mgr;m and smaller than 2 mm.
Especially, the anode electrode, the transparent electrode shown in
FIG. 1
, is used as a display signal bus and an acceleration electrode of electrons at the same time, low voltage operation is almost impossible. That is, since high-energy electrons of more than 200 eV are required to illuminate phosphors in field emission display, a voltage of more than 200V should be biased to the anode electrode. Also, since the structure of diode-type field emitters is thin-film type, the attribute of electron emission is not stable and therefore uniformity is low.
Also, pixels of a conventional field emission display with diode-type field emitters are not electrically isolated each other. Therefore, as the size and resolution of displays increase, the cross-talk of display signals becomes worse.
SUMMARY OF THE INVENTION
The present invention provides a field emission display with diode-type field emitters, which can be operated with low-voltage driver circuits and therefore a high-resolution large-screen display can be implemented.
A field emission display with diode-type field emitters comprises an upper plate and a lower plate. The upper plate and the lower plate are vacuum-packaged in parallel. The lower plate comprises a plurality of column signal buses and a plurality of row signal buses, film type field emitters, and switching devices. The column signal buses and the row signal buses are made of metallic material. Pixels are defined by the column signal buses and the row signal buses. A film-type field emitter and a switching device are formed inside each pixel. The switching device controls the field emitter on the basis of scan signals and data signals. The scan signals and data signals are loaded to the switching device through said column signal buses and said row signal buses. The switching device includes at least three electrodes for connection with the column signal bus, the row signal bus, and the field emitter.
The upper plate comprises phosphors and anode electrodes for accelerating electrons with high energy. The electrons are emitted from the field emitters of the lower plate.
Desirably, the film-type field emitter is made of diamond.
Desirably, the film-type field emitter is made of diamond-like carbon.
Desirably, film-type field emitter is made of carbon nanotube.
Desirably, the switching device is a transistor. The gate of the transistor is connected with a row signal bus. The source of the transistor is connected with a column signal bus. The drain of the transistor is connected with the field emitter. The column signal bus and the row signal bus define a pixel.
Desirably, the switching device further comprises a resistor, with the transistor, between the drain of the transistor and the field emitter.
Desirably, the switching device further comprises a high-voltage transistor, with the transistor. The source of the high-voltage transistor is connected with the drain of the transistor and the drain of the high-voltage transistor is connected with the field emitter. The high-voltage transistor includes a gate.
Desirably, the switching device further comprises a resistor, with the transistor and the high-voltage transistor, between the drain
Cho Kyoung Ik
Kang Seung Youl
Lee Jin Ho
Song Yoon Ho
Electronics and Telecommunications Research Institute
Seed IP Law Group PLLC
Vo Tuyet T.
Wong Don
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