Image-forming device

Details Image-forming device Image-forming device

2001-11-14

2004-03-16

Ramsey, Kenneth J. (Department: 2879)

Electric lamp or space discharge component or device manufacturi

Process

With assembly or disassembly

C313S422000

Reexamination Certificate

active

06705909

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image-forming device employing electron-emitting elements.
2. Related Background Art
Hitherto thin plate-type image-forming devices have been used, in which a plurality of electron-emitting elements are arranged in a plane and are counterposed to image-forming members for forming images by electron beam irradiation (a member which emits light, changes its color, become electrified, or denaturated by collision of electrons, e.g., a fluorescent material, and a resist material).
FIGS. 35 and 36
show an outline of construction of a conventional electron beam display device as an example of the image-forming device.
FIG. 36
shows a sectional view at A-A′ in FIG.
35
.
The construction of the conventional electron-beam display device shown in
FIGS. 35 and 36
is described below in detail. A rear plate
101
, an external frame
111
, and a face plate
109
constitute an envelope. The interior of the envelope is maintained in vacuum. Electrodes
103
a
and
103
b
, and an electron-emitting section
104
constitute an electron-emitting element
105
. A scanning electrode
102
a
and an information signal electrode
102
b
are wiring electrodes, and are connected respectively to the electrodes
103
a
and
103
b
. A glass substrate
106
, a transparent electrode
107
, and a fluorescent material (an image-forming member)
108
constitute the face plate
109
. The numeral
112
indicates a luminescent spot, and the numeral
110
indicates a supporting member for supporting the envelope against the atmospheric pressure. The electron-beam display device displays an image by application of signal voltages between scanning electrodes
102
a
and information signal electrodes
102
b
arranged in an X-Y matrix to project an electron beam onto the fluorescent material
108
in correspondence with information signals. As the electron-emitting element
105
, useful are thermoelectron-emitting elements in which electrons are emitted from the electron-emitting section
104
on heating; field emission elements disclosed in U.S. Pat. Nos. 3,755,704 and 4,904,895; and surface conduction type emitting elements disclosed in U.S. Pat. No. 5,066,883.
In the above-described plane type electron beam display device, the inside of the envelope is kept at a vacuum. A supporting member
110
is provided between the rear plate
101
and the face plate
109
as shown in
FIG. 36
to support the envelope internally against the external atmospheric pressure. The supporting member
110
is usually made of an insulating material to give dielectric strength against high voltage applied between the fluorescent material
108
(or the transparent electrode
107
) and the electron-emitting element
105
. The supporting member is indispensable for simplification, miniaturization, and weight reduction of the entire device, since an electron beam display device having a larger display surface is subjected to a larger total atmospheric pressure.
However, conventional electron beam display devices mentioned above, as shown in
FIGS. 35 and 36
, have a supporting member
110
made of an insulating material, which will be electrified at the surface by undesired collision of electrons and ions thereto. The electrification of the supporting member causes the problems as below: (1) The electron beam is deflected owing to the electrification, whereby the quantity of irradiation of electron beam onto the desired fluorescent material in the picture elements fluctuates to cause irregularity in luminance and color. In particular, when the quantity of the electrification is large, the electron beam is not projected to the desired fluorescent material but is directed to undesired adjacent fluorescent material to cause crosstalk; (2) The quantity of electrification varies with lapse of time, which causes time-variation of the electron path, resulting in variation in the intensity of the luminance; and (3) Electric discharge occurs at the electrified supporting member, which may damage the electron-emitting element or deteriorate the insulating property of the supporting member.
Thereby, the metal cover
113
is kept at the same voltage as the transparent electrode (fluorescent material
108
). Generally, the transparent electrode
107
is kept at a high potential so as to capture the electron beam. When the metal cover is kept at a high potential is placed in proximity to the electron-emitting element
105
, the electron beam emitted from the electron-emitting element
105
is deflected toward the side of the metal cover
113
, causing different problems mentioned below: (4) A fraction of the electron beam is captured by the metal cover, whereby the intensity of the electron beam is lowered and the luminance of the fluorescent material is lowered at the proximity to the supporting member, causing irregularity of the luminance; and (5) The potential applied to the transparent electrode (fluorescent material) cannot exceed a certain value, whereby the luminance is low, red-light emitting and blue-light emitting fluorescent material cannot be used, and therefore a full-color image cannot be displayed.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an image-forming device having a sufficient supporting structure to withstand the atmospheric pressure, being free from cross talk, and being improved in picture image contrast and in uniformity of the luminance.
Another object of the present invention is to provide a stable image-forming device which is free from time-variation of the luminance.
A further object of the present invention is to provide an image-forming device which gives a color image with high contrast or with high luminance.
A still further object of the present invention is to provide an image-forming device which is free from discharging of the supporting member, and has a long life.
According to an aspect of the present invention, there is provided an image-forming device having, in an envelope, an electron-emitting element, an image-forming member for forming an image by irradiation of an electron beam emitted from the electron-emitting element, and an electroconductive supporting member for supporting the envelope (internally), wherein the device comprises a means for controlling the potential of the supporting member to not be higher than the maximum potential applied to the electron-emitting element.
According to another aspect of the present invention, there is provided an image-forming device having, in an envelope, an electron-emitting element for emitting an electron beam by application of voltage between electrodes, an image-forming member for forming an image by irradiation of the electron beam emitted from the electron-emitting element, and an electroconductive supporting member for supporting the envelope, wherein the supporting member is connected electrically to one of the electrodes.
According to still another aspect of the present invention, there is provided an image-forming device having, in an envelope, an electron-emitting element for emitting an electron beam on application of voltage between electrodes, an image-forming member for forming an image by irradiation of the electron beam emitted from the electron-emitting element, and an electroconductive supporting member for supporting the envelope, wherein the supporting member is connected electrically to a lower potential electrode of said electrodes.
According to a further aspect of the present invention, there is provided an image-forming device having, in an envelope, an electron-emitting element, an image-forming member for forming an image by irradiation of an electron beam emitted from the electron-emitting element, and an electroconductive supporting member for supporting the envelope, wherein the electron-emitting element and the image-forming member are placed in juxtaposition on the same substrate, a potential-defining electrode is additionally provided in opposition to the substrate to define the potential of the space

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