Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
2001-08-28
2003-09-23
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S495000, C313S497000, C313S309000, C313S310000, C313S311000, C313S422000
Reexamination Certificate
active
06624566
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum fluorescent display which emits light by bombarding electrons emitted from a field emission type electron-emitting source against a phosphor.
Conventionally, as a display component for an audio apparatus or automobile dashboard, a vacuum fluorescent display is one type of electronic display device frequently used. In the vacuum fluorescent display, an anode attached with a phosphor and a cathode are arranged in a vacuum vessel to oppose each other, and electrons emitted from the cathode are bombarded against the phosphor to emit light. As a general vacuum fluorescent display, a triode structure is used most often, in which a grid for controlling the electron flow is provided between the cathode and anode, so the phosphor selectively emits light.
Recently, to greatly increase the luminance of the vacuum fluorescent display, a vacuum fluorescent display in which a field emission type electron-emitting source using carbon nanotubes is used as a cathode is proposed.
FIG. 7
shows a conventional vacuum fluorescent display. Referring to
FIG. 7
, the conventional vacuum fluorescent display has an envelope
300
constituted by a front glass member
301
which has light transmission properties at least partly, a substrate
302
opposing the front glass member
301
, and a frame-like spacer
303
for hermetically connecting the edges of the front glass member
301
and substrate
302
. The interior of the envelope
300
is vacuum-evacuated.
In the envelope
300
, a plurality of front surface support members
304
vertically stand on the inner surface of the front glass member
301
to be parallel to each other at a predetermined interval. Each light-emitting portion
310
constituting a display pixel is formed on a corresponding region on the inner surface of the front glass member
301
which is sandwiched by the front surface support members
304
. The light-emitting portion
310
is constituted by a band-like phosphor film
311
formed on the inner surface of the front glass member
301
and a metal back film
312
formed on the surface of the phosphor film
311
and used as an anode.
A plurality of substrate support members
305
vertically stand on the substrate
302
to oppose the front surface support members
304
. A plurality of band-like wiring electrodes
320
are formed in regions on the inner surface of the substrate
302
each of which is sandwiched by the substrate support members
305
to oppose the respective light-emitting portions
310
. Field emission type electron-emitting sources
330
made of carbon nanotubes are formed on the wiring electrodes
320
, respectively. Further, a plurality of mesh-like electron extracting electrodes
340
are arranged to be spaced apart from the field emission type electron-emitting sources
330
by a predetermined distance. The electron extracting electrodes
340
are formed in the direction perpendicular to the field emission type electron-emitting sources
330
to have a band-like shape, and arranged to be parallel to each other at a predetermined interval. The electron extracting electrodes
340
are sandwiched and fixed between the substrate support members
305
and front surface support members
304
.
The operation of the vacuum fluorescent display will be described next with reference to FIG.
8
. Note that the support members
304
, and the support members
305
, arranged between the electrodes are not shown in FIG.
8
. Referring to
FIG. 8
, the field emission type electron-emitting sources
330
are arranged to be parallel to each other at a predetermined interval, and the electron extracting electrodes
340
are arranged above the field emission type electron-emitting sources
330
. The electron extracting electrodes
340
are formed in the direction perpendicular to the field emission type electron-emitting sources
330
and arranged to be parallel to each other at a predetermined interval. The plurality of light-emitting portions
310
are arranged above the electron extracting electrodes
340
at positions opposing the respective field emission type electron-emitting sources
330
.
A positive voltage (accelerating voltage) is applied to the metal back films
312
of the light-emitting portions
310
. In this state, in the vacuum fluorescent display, voltages applied to each field emission type electron-emitting source
330
and each electron extracting electrode
340
switch the ON/OFF states of a corresponding one of the light-emitting portions
310
which opposes the intersecting region of the field emission type electron-emitting source
330
and electron extracting electrode
340
. In this vacuum fluorescent display, when 0 V is applied to the electron extracting electrode
340
, an electric field required for emitting electrons is not generated in the field emission type electron-emitting sources
330
. Accordingly, the light-emitting portion
310
becomes an OFF state
310
a
independently of a voltage applied to the field emission type electron-emitting source
330
.
When a predetermined positive voltage is applied to the electron extracting electrode
340
, a voltage applied to each field emission type electron-emitting source
330
through a corresponding one of the wiring electrodes
320
can switch the ON/OFF states of a corresponding one of the light-emitting portions
310
which opposes the intersecting region of the field emission type electron-emitting source
330
and electron extracting electrode
340
. In this case, when a voltage applied to the field emission type electron-emitting source
330
is 0 V, the light-emitting portion
310
becomes an ON state
310
b
, and when a predetermined positive voltage is applied to the field emission type electron-emitting source
330
, the light-emitting portion
310
becomes the OFF state
310
a
. Accordingly, in this vacuum fluorescent display, scanning is performed such that the positive voltage is sequentially applied to the respective electron extracting electrodes
340
, and in synchronism with this scanning, voltages applied to the respective field emission type electron-emitting sources
330
are switched in correspondence with the respective pixels to be displayed, thereby performing matrix display.
In the conventional vacuum fluorescent display, however, the electron-emitting sources are formed on the substrate. Therefore, when faults such as a luminance nonuniformity and the like have been found in the electron-emitting source, the substrate itself must be discarded, thereby causing a decrease in manufacturing yield.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vacuum fluorescent display using a field emission type electron-emitting source which increases the manufacturing yield.
In order to achieve the above object, according to the present invention, there is provided a vacuum fluorescent display comprising a front glass member which has light transmission properties at least partly, a substrate opposing the front glass member through a vacuum space, a control electrode formed on an inner surface of the substrate, a plate-like field emission type electron-emitting source with a plurality of through holes which is arranged in the vacuum space to be spaced apart from the control electrode, a mesh-like electron extracting electrode formed between the field emission type electron-emitting source and the front glass member to be spaced apart from the field emission type electron-emitting source, and a phosphor film formed inside the front glass member.
REFERENCES:
patent: 5214347 (1993-05-01), Gray
patent: 6135839 (2000-10-01), Iwase et al.
patent: 6239547 (2001-05-01), Uemura et al.
patent: 6455989 (2002-09-01), Nakada et al.
patent: 6465132 (2002-10-01), Jin
patent: 6489710 (2002-12-01), Okita et al.
Kurachi Hiroyuki
Nagasako Takeshi
Uemura Sashiro
Yamada Hiromu
Yotani Junko
Blakely & Sokoloff, Taylor & Zafman
Hodges Matt
Ise Electronics Corporation
Patel Vip
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