Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
2001-12-05
2004-10-12
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S496000, C313S497000, C313S500000, C313S422000, C445S024000
Reexamination Certificate
active
06803717
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image displaying apparatus utilizing an electron beam such as a field emission display (FED) and a cathode-ray tube (CRT).
2. Related Background Art
So far, image displaying apparatuses such as CRT's have always been required to have further larger screens, and research therefor is lively being performed. Moreover, as the screens become larger, it becomes an important problem to make the apparatuses thinner in thickness, lighter in weight, and lower in costs. However, because a CRT deflects electrons accelerated by a high voltage with the deflection electrode thereof to excite the phosphor on the face plate thereof, it becomes necessary to lengthen the depth thereof in principle, and then it becomes difficult to provide a CRT thin in thickness and light in weight. The present inventors have researched in respect of a surface conduction electron-emitting device and an image displaying apparatus using the surface conduction electron-emitting device as an image displaying apparatus capable of resolving such a problem.
For example, the inventors have tried to apply a multi-electron beam source by an electric wiring method shown in
FIG. 11
to an image displaying apparatus. That is, the inventors have tried to compose an image displaying apparatus by using a multi-electron beam source in which many surface conduction electron-emitting devices are arranged two-dimensionally and the arranged surface conduction electron-emitting devices are wired in a passive matrix as shown in FIG.
11
. In
FIG. 11
, a reference numeral
4001
designates a surface conduction electron-emitting device shown mimetically; a reference numeral
4002
designates a piece of wiring in a row direction; and a reference numeral
4003
designates a piece of wiring in a column direction. Incidentally, although a six by six matrix is shown in
FIG. 11
on account of the convenience of description, the scale of the matrix is not limited to the six by six one, and devices necessary for displaying a desired image can be arranged.
FIG. 12
shows the structure of a cathode-ray tube using the multi-electron beam source. The structure comprises an outer housing bottom
4005
including a multi-electron beam source
4004
, an outer housing frame
4007
, and a face plate
4006
including a phosphor layer
4008
and a metal-backing
4009
. Moreover, the phosphor layer
4008
on the face plate
4006
includes phosphor thereby excited by an electron beam to emit light, and a black matrix for suppressing the reflection of outer light to prevent color mixture in the phosphor. A high electric potential Va is applied to the phosphor layer
4008
and the metal-backing
4009
through a high voltage terminal
4011
, and the phosphor layer
4008
and the metal-backing
4009
constitutes an anode.
For the outputting of a desired electron beam from the multi-electron beam source
4004
in which surface conduction electron-emitting devices
4001
are wired in a passive matrix, appropriate electric signals are applied to the pieces of wiring
4002
in row directions and the pieces of wiring
4003
in column directions of the multi-electron beam source
4004
. For example, for the drive of the surface conduction electron-emitting devices
4001
in an arbitrary row of the matrix, a selection potential Vs is applied to the wiring
4002
in the row direction to be selected, and at the same time a nonselection potential Vns is applied to the wiring
4002
in the row directions not to be selected. Synchronously to this, a drive potential Ve for outputting electron beams is applied to the pieces of the wiring
4003
in the column directions.
By this method, the voltages Ve and Vs are applied to the surface conduction electron-emitting devices
4001
of the rows to be selected, and the voltages Ve and Vns are applied to the surface conduction electron-emitting devices
4001
of the rows not to be selected. By the settings of the voltages Ve, Vs and Vns to be appropriate potentials, electron beams having desired strength can be outputted only from the surface conduction electron-emitting devices
4001
of the rows to be selected. And, when drive potentials Ve having different strength from each other are applied to each of the wiring
4003
in the column directions, electron beams having different strength are outputted from each surface conduction electron-emitting devices
4001
in the row to be selected. Moreover, because the response speed of the surface conduction electron-emitting devices
4001
is high, the length of time during which electron beams are outputted can also be changed by the change of the length of time during which the drive potential Ve is applied.
By the application of such electric potentials, the electron beams outputted from the multi-electron beam source
4004
irradiate the metal-backing
4009
, which the high electric potential Va is applied to, and excite the phosphor, or the target, to make the phosphor emit light. Moreover, in the image displaying apparatus, the high electric potential Va (sometimes referred to as an “accelerating potential” or an “anode potential”) is applied to the metal-backing
4009
to generate an electric field between the outer housing bottom
4005
(sometimes referred to as a “rear plate”) and the face plate
4006
. Thereby, electrons emitted from the multi-electron beam source
4004
are accelerated and excite the phosphor to emit light. Consequently, an image is formed.
Now, because the brightness of an image displaying apparatus depends on an accelerating potential greatly, it is necessary to heighten the accelerating potential for the realization of high brightness. Moreover, because the thickness of an image displaying panel should be thinned for the realization of the thinning of the image displaying apparatus, the distance between the rear plate
4005
and the face plate
4006
should be shorten therefor. Consequently, a considerably high electric field is generated between the rear plate
4005
and the face plate
4006
.
SUMMARY OF THE INVENTION
Now, in the structure equipped with an anode to which accelerating potential for accelerating an electron is applied, undesirable discharges are sometimes generated between the anode and other members.
The inventors of the present invention planned to dispose a potential regulating electrode capable of suppressing the discharge between the anode and any other member capable of generating a creeping discharge between the anode at a halfway point of a creepage between the anode and the other member.
As a result of the zealous consideration, the present inventors found a fact that the employment of a structure in which a further spacing member is disposed in the structure having the potential regulating electrode would cause the problem of an abnormal discharge owing to the existence of the spacing member.
One object of the invention is to realize a structure capable of suppressing undesirable discharges in a structure including an anode, a potential regulating electrode and a spacing member.
An image displaying apparatus according to the present invention is composed as follows. That is, an image displaying apparatus comprising:
a first plate including at least an electron beam source;
a second plate including an anode to which an electric potential for accelerating an electron beam from the electron beam source is applied, and a potential regulating electrode to which a predetermined electric potential lower than that of the anode is applied, the potential regulating electrode being situated at an outside of the anode; and
a spacing member provided between the first and second plates, the spacing member contacting both of the anode and the potential regulating electrode, the spacing member including an electrode contacting or being disposed close to the potential regulating electrode thereby electrically coupled with the potential regulating electrode.
Moreover, in the aforesaid invention, a configuration in which the spacing member further inclu
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Roy Sikha
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