Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
2000-02-23
2003-04-01
O'Shea, Sandra (Department: 2875)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S495000, C313S461000, C313S470000, C313S472000
Reexamination Certificate
active
06541907
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus utilizing electron beams.
2. Related Background Art
In an image forming apparatus including a cathode ray tube (CRT), further size enlargement has been demanded and researches have intensively been performed. Moreover, with the size enlargement, the thinning, lightening and cost reduction of the apparatus have become an important problem. However, since the CRT deflects the electrons accelerated with a high voltage with a deflecting electrode, and excites phosphors on a face place, in principle, a depth is necessary for the size enlargement, and it is difficult to provide a thin and light apparatus. As the image forming apparatus which can solve the above-described problem, the inventors have researched a surface conduction electron emitting device, and an image display using the surface conduction electron emitting device.
The inventors have attempted applying a multi-electron beam source by an electric wiring method, for example, as shown in FIG.
11
. Specifically, a multiplicity of surface conduction electron emitting devices are two-dimensionally arranged, and these devices are wired in a simple matrix form as shown in
FIG. 11
to form the multi-electron beam source.
In
FIG. 11
, numeral
4001
schematically denotes the surface conduction electron emitting device,
4002
denotes a row direction wiring, and
4003
denotes a column direction wiring. Additionally, for convenience of the drawing, a 6×6 matrix is shown, but the scale of the matrix is not limited to this, and a sufficient number of devices for performing a desired image display are arranged and wired.
FIG. 12
shows the structure of the image forming apparatus using the multi-electron beam source, and the structure includes a rear plate
4005
provided with a multi-electron beam source
4001
, an outer frame
4007
, a face plate
4006
provide with a fluorescent layer
4008
, and a conductive member (metal back)
4009
. Moreover, a high voltage of several kilovolts to several tens of kilovolts is applied to the conductive member (metal back)
4009
disposed on the face plate
4006
via a high-voltage introduction terminal
4011
from a high-voltage power source
4010
.
In order to output desired electron beams in the multi-electron beam source in which the surface conduction electron emitting devices are wired in the simple matrix, appropriate electric signals are applied to the row direction wiring
4002
and the column direction wiring
4003
. For example, to drive one arbitrary row of surface conduction electron emitting devices in the matrix, a selection voltage Vs is applied to the row direction wiring
4002
of the selected row, and additionally a non-selection voltage Vns is applied to the row direction wiring
4002
of a non-selected row. In synchronization with this, a drive voltage Ve is applied to the column direction wiring
4003
to output the electron beams. According to this method, a voltage Ve-Vs is applied to the surface conduction electron emitting devices of the selected row, and a voltage Ve-Vns is applied to the surface conduction electron emitting devices of the non-selected row. When Ve, Vs, Vns are set to voltages with appropriate magnitudes, the electron beams with desired intensities are outputted only from the surface conduction electron emitting devices of the selected row. Moreover, when different drive voltages Ve are applied to the column direction wirings, the electron beams with different intensities are outputted from the devices of the selected row. Moreover, since the response rate of the surface conduction electron emitting device is high, by changing a time length for applying the drive voltage Ve, the time length for outputting the electron beams can also be changed.
The electron beams outputted from the multi-electron beam source
4001
by applying the voltage as described above are radiated to the conductive member (metal back)
4009
to which a high voltage Va is applied, so that the fluorescent layer (image forming member)
4008
as a target is excited to emit light. Therefore, for example, by appropriately applying a voltage signal in accordance with image information, an image display is constituted.
The image forming apparatus applies the high voltage Va to the conductive member (metal back)
4009
, produces an electric field between the rear plate
4005
and the face plate
4006
to accelerate the electrons, and excites the fluorescent material to emit light so that an image is formed.
Here, to realize the thinning of the image forming apparatus, the thickness of the image forming apparatus needs to be reduced, and for this purpose a distance between the rear plate
4005
and the face plate
4006
has to be reduced. Since the interval between the rear plate
4005
and the face plate
4006
is set to about several millimeters, a high electric field of 1 kV/mm or more is produced between the rear plate
4005
and the face plate
4006
.
The conductive member (metal back)
4009
has a purpose of applying the high voltage Va to the entire fluorescent layer, preventing the fluorescent material from being charged, and extracting the light emitted rearward (rear plate direction) from the fluorescent material toward the front by a mirror surface effect. Therefore, the conductive member (metal back) is preferably a continuous film. Moreover, the metal back
4009
needs to be a very thin film because the accelerated electrons have to be passed through the metal back
4009
to excite the fluorescent material. However, the fluorescent material is usually powder, the fluorescent film becomes porous, and considerable surface irregularities are present.
Moreover, particularly when the fluorescent materials of three primary colors (red, blue, green) are disposed as the fluorescent film, a black interval defining member (black matrix or black stripe) is usually disposed between the color fluorescent materials in order to prevent a mixed color between the color fluorescent materials, define the interval between the color fluorescent materials, prevent color deviation from occurring even when the electron beam position slightly deviates, and to absorb external light and enhance image contrast, and for other reasons. The considerable irregularities are also present on the surface of the interval defining member.
For the above-described reasons, a filming process is usually performed before the conductive member (metal back) is prepared, because the continuous film cannot be formed by directly forming the film of the conductive member (metal back)
4009
.
The filming process comprises preparing an acrylic resin film on the surface of the fluorescent layer, and flatting the surface of the fluorescent layer. Subsequently, by forming a film of conductive member on the flatted film by a vacuum deposition process or the like, the conductive member (metal back) can be prepared as the continuous film. Moreover, after the conductive member (metal back) is prepared, the resin film is calcined and removed by thermal decomposition.
SUMMARY OF THE INVENTION
There is provided an image forming apparatus comprising: a rear plate having an electron emitting device; and a face plate having a conductive film, and a fluorescent layer comprising fluorescent particles, the conductive film being disposed on the fluorescent layer. When the average thickness of the fluorescent layer is set to d, the average particle diameter of the fluorescent particles is rp, and the thickness of the fluorescent layer is D, D−rp≦d≦D+rp is satisfied.
Moreover, in the image forming apparatus of the present invention, the fluorescent layer includes a fluorescent film, and an interval defining member adjacent to the fluorescent film. When the average thickness of the fluorescent film is set to tp, and the average thickness of the interval defining member is tb, tp−rp≦tb≦tp+rp is satisfied.
Furthermore, in the image forming apparatus of the present invention, the fluorescent
Lee Guiyoung
O'Shea Sandra
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