U.S. patent number 3,796,905 [Application Number 05/305,578] was granted by the patent office on 1974-03-12 for cathode-ray tube having prism-shaped fibre optics faceplate.
This patent grant is currently assigned to Matsushita Electric Industrial Company. Invention is credited to Haruo Maeda, Eiichi Miyazaki, Kaoru Tomii.
United States Patent |
3,796,905 |
Tomii , et al. |
March 12, 1974 |
CATHODE-RAY TUBE HAVING PRISM-SHAPED FIBRE OPTICS FACEPLATE
Abstract
A cathode-ray tube including a fibre optics faceplate having two
slanted front end faces angled from a plane perpendicular to the
axes of the optical fibres of the faceplate. The fibre optics
faceplate is cut into two pieces along an intermediate plane
substantially perpendicular to the axes of the optical fibres.
Inventors: |
Tomii; Kaoru (Kawasaki,
JA), Miyazaki; Eiichi (Kawasaki, JA),
Maeda; Haruo (Kawasaki, JA) |
Assignee: |
Matsushita Electric Industrial
Company (Osaka, JA)
|
Family
ID: |
13991441 |
Appl.
No.: |
05/305,578 |
Filed: |
November 10, 1972 |
Foreign Application Priority Data
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|
|
|
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Nov 10, 1971 [JA] |
|
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46-90186 |
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Current U.S.
Class: |
313/375;
385/120 |
Current CPC
Class: |
H01J
29/892 (20130101) |
Current International
Class: |
H01J
29/89 (20060101); H01j 029/18 () |
Field of
Search: |
;313/89LF,92LF |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: Chatmon, Jr.; Saxfield
Claims
1. In a cathode-ray tube having a prism-shaped fiber-optics
faceplate, the improvement wherein said fiber-optics faceplate
comprises:
a first fiber-optics member having two end faces substantially
perpendicular to the axes of the fibers, one of said faces facing
the electron gun of said cathode-ray tube and being coated with a
phosphorous layer;
a second fiber optics member having one end face substantially
perpendicular to the axes of the fibers and having at the other end
portion thereof two slanted end faces angled from a plane
perpendicular to the axes of the fibers in such a manner as to meet
edgewise each other; and means disposed between said first and
second fiber optics members and holding said one end face of said
second fiber optics member in contact with the other face of said
first fiber-optics member and permitting sliding movement
therebetween in a direction substantially perpendicular to the axis
of the fibers in said members.
Description
The present invention relates to cathode-ray tubes and more
particularly to a cathode-ray tube having a fibre optics faceplate.
The specific purpose of the invention is to provide an improved
cathode-ray tube with a fibre optics faceplate having an extremely
long life-time.
Generally the cathode-ray tube of the present invention includes a
prism-shaped fibre optics faceplate, that is, a fibre optics
faceplate having two slanted front end faces angled from a plane
perpendicular to the axes of optical fibres constituting the
faceplate, the prism-shaped faceplate being cut into two pieces
along a plane substantially perpendicular to the axes of the
optical fibres. A front side piece of the two pieces will be moved
or slide relative to the other piece so as to maintain operable the
overall cathode-ray tube even if a portion of the phosphorous layer
of the cathode-ray tube is degraded or defective. The prism-shaped
fibre optics faceplate is disclosed in detail in out co-pending
application Ser. No. 242,009 filed Apr. 7, 1972, now U.S. Pat. No.
3,732,367.
The specific structure of the present invention will be understood
when the detailed description is read in conjunction with the
accompanying drawings in which:
FIG. 1 is a side view showing a known cathode-ray tube having a
prism-shaped fibre optics faceplate;
FIGS. 2A and 2B are sectional views showing on an enlarged scale
the prism-shaped fibre optics faceplate of the cathode-ray tube of
FIG. 1;
FIGS. 3A and 3B are sectional views showing a prism-shaped fibre
optics faceplate in different forms;
FIG. 4 is a perspective view showing a front-side piece of the
fibre optics faceplate shown in FIGS. 3A and 3B;
FIG. 5 is a perspective view showing a pair of support members for
supporting the front-side piece shown in FIG. 4;
FIG. 6 is a perspective view showing the support members and the
front-side piece and the support members assembled; and
FIG. 7 is a sectional view showing the front and portion of a
cathode-ray tube according to the invention, wherein the assembly
shown in FIG. 6 is secured to the cathode-ray tube.
With reference to the drawings and more particularly to FIG. 1
thereof, there is illustrated a cathode-ray tube 10 which is in
detail disclosed in the co-pending application Ser. No. 242,009.
The cathode-ray tube 10 generally includes an evacuated envelope
11, and a prism-shaped fibre optics faceplate 12 attached to the
front end of the bulb portion of the envelope 11. The inner or
electron gun side surface of the faceplate 12 is coated with a
phosphorous layer 13.
In FIGS. 2A and 2B, there is illustrated on an enlarged scale the
prism-shaped fibre optics faceplate 12 of the cathode-ray tube 10.
As shown, the fibre optics faceplate 12 has two slanted front end
faces 12A and 12B angled from a plane perpendicular to the axes of
the optical fibres in such a manner as to meet edgewise each other
at a ridge 12C. The cathode-ray tube 10 is incorporated in an image
pick-up and/or recording system such as a faximile system to permit
the cathode-ray tube 10 to serve as a scanning means for scanning a
recording medium with a moving light spot or rather a
flying-spot.
In the picking up operation, a recording medium 14 carrying
patterned information thereon is positioned on and along the end
face 12B, and the electron beam, indicated by an arrow 15,
generated in the cathode-ray tube is aligned to hit a portion of
the phosphorous layer 13 corresponding to the end face 12A. The
bombardment of the phosphorous layer 13 by the electron beam 15
generates a flying-spot moving along the ridge 12C since the
electron beam 15 is deflected in that direction. The flying-spot
generated in the phosphorous layer 13 is delivered through the
fibre optics faceplate 12 to the end face 12A. After the
flying-spot is refracted and accordingly focussed at the end face
12A, the flying-spot is irradiated onto the recording medium 14 and
reflected by the recording medium 14, as indicated by an arrow 16
and picked up by a photo-electric converter 17 positioned in the
vicinity of the faceplate 12. Since, in this instance, the electron
beam 15 has a constant intensity, the reflected flying-spot has an
instantaneous intensity according to the patterned information on
the recording medium 14. The recording medium 14 is, on the other
hand, continuously fed in synchronism with the scanning rate of the
flying-spot by a suitable feeding means (not shown) so that the
photo-electric converter 17 produces an electric image signal
representing the patterned information on the recording medium 14.
The electric image signal is then processed by a suitable electric
circuit arrangement (not shown).
In the recording operation of the system employing the cathode-ray
tube 10, a photo-sensitive recording medium 14 is positioned on and
along the end face 12B, and the electron beam 15 is aligned to
impinge another portion of the phosphorous layer 13 corresponding
to the end face 12B. The electron beam 15 is deflected in the same
manner as in the picking up operation but, in this case, the
electron beam 15 is intensity-modulated by an image signal carrying
thereon one or more pieces of image information so that a
flying-spot has an instantaneous intensity proportional to that of
the electron beam 15. The flying-spot generated in the phosphorous
layer 13 is delivered through the faceplate 12 to the end face 12B
and irradiated onto the recording medium 14. Since, therefore, the
recording medium 14' is continuously fed in synchronism with the
scanning rate of the flying-spot by a suitable means (not shown),
the pieces of the information are recorded on the recording medium
14.
It is, in this instance, to be noted that the electron beam 15
should be, in the pick-up operation, so aligned that the
flying-spot passes through a portion or rather an operative portion
of the end face 12A as near to the ridge 12C as possible thereby to
suppress the diffusion of the flying-spot during the advancement
from the end face 12A to the surface of the recording medium 14 and
to produce an image signal having an increased resolution power.
The electron beam 15, therefore, repeatedly impinges on only a
limited portion of the phosphorous layer 13. It is accordingly a
problem that the repeated impingement of the electron beam 15 onto
the limited portion of the layer 13 causes to shorten the life-time
of the particular portion of the layer 13. Further, when the
limited portion of the layer 13 is merely partly degraded or
defective, the overall cathode-ray tube becomes unavailable.
In order to solve the above-stated drawbacks of the known
cathode-ray tube with a prism-shaped fibre optics faceplate, an
improved cathode-ray tube is provided according to the present
invention.
In FIGS. 3A and 3B, there is shown on an enlarged scale a
prism-shaped fibre optics faceplate of a cathode-ray tube according
to the invention. The fibre optics faceplate, generally designated
by 22, is cut into two pieces, that is first and second members 22A
and 22B, along an intermediate plane substantially perpendicular to
the axes of the optical fibres. The cut surfaces of the members 22A
and 22B facing each other should be flat and clear thereby to
provide a slidable and hermetically sealed contact between the
surfaces.
As long as, in operation, a portion of the phosphorous layer 13
corresponding to the operative portion of the end face 12A
maintains its fluorescence, the first and second members 22A and
22B are flush with each other as shown in FIG. 3A, and the
faceplate 22 operates in the same manner as the faceplate 12 shown
in FIGS. 2A and 2B. When the portion of the phosphorous layer 13 is
degraded or defective, the first and second members 22A and 22B are
slid along the cut surfaces thereof relative to each other until
the members 22A and 22B take such relative positions as shown in
FIG. 3B, and the electron beam 15 is aligned to impinge another
portion of the phosphorous layer 13 which is still satisfactorily
fluorescent and now corresponds to the operative portion of the end
face 12A, as shown in FIG. 3B. When, thereafter, the portion of the
layer 13 which is hit by the electron beam 15 is again degraded or
defective, the members 22A and 22B are further slid relative to
each other and the alignement of the electron beam 15 is further
changed so as to make the flying-spot to pass thorough the
operative portion of the end face 12A.
FIG. 4 perspectively illustrates the second member 22B.
FIG. 5 perspectively illustrates a pair of support members 30 and
30 which are shown decoupled from each other. The support member 30
has a generally square cross-section and has an inclined guiding
surface 31 at the central portion thereof. Two grooves 32 and 33
are formed at the both side end portions thereof. The support
member 30' has the same configuration as that of the support member
30. The support members 30 and 30' are to be coupled through a pair
of screw bores 34 and 34' by means of screws 36 and 36' so as to
support the second member 22B of a cathode-ray tube according to
the invention, as shown in FIG. 6. Being apparent from FIG. 6, the
slanted end faces of the second member 22B are flush with the
inclined guide surfaces 31 and 31' of the support members 30 and
30', respectively. The guide surfaces of the support members 30 and
30' are convenient for smoothly advancing a recording medium to be
placed on the faceplate of the cathode-ray tube.
The thus assembled support members 30 and 30' sandwitching the
second member 22B are mounted through the grooves 32 and 33 thereof
on support rods 37 and 37' by means of suitable means such as
screws 38 and 38', so that the second member 22B meets the first
member 22A in such a manner as shown in FIG. 3A or 3B. The support
rods 37 and 37' are, of course, fixed relative to the cathode-ray
tube.
When it is intended to move or slide the second member 22B relative
to the first member 22A, the screw 38 and 38' are loosened and the
assembled support members 30 and 30' are displaced to position the
second member 22B in a new position relative to the first member
22A.
It will be apparent from the above-detailed description that an
improved cathode-ray tube with a prism-shaped fibre optics
faceplate has been provided.
It will also be understood that the invention is not to be limited
to the exact construction shown and described without departing
from the scope of the invention, as defined by the appended
claims.
* * * * *