Patent US3925699A successfully refreshed from Google Patents.
US3925699A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pick-up tubes
Assignee: Teledyne UK Ltd
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Filing: 1971-07-26
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Granted: 1975-12-09
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Expires: 1991-07-26
Abstract
Abstract The invention provides a photo-conductive target pick-up tube in which light is introduced into the tubular anode electrode on the gun cathode side of the target. The light is introduced evenly around the circumference of the anode, the inner surface of which is roughened to achieve diffused illumination of the rear of the target. In operation of the tube an artificial dark current is obtained which tends to reduce build up and deca
Inventors
- 👤 Peter Baldwin Banks
- 👤 Hans Scholz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:27
CPC Classifications
H; H01; H01J; H01J31/00; H01J31/08; H01J31/26; H01J31/28; H01J31/34; H01J31/38
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
343 words
In a television camera tube of the type comprising an evacuated envelope having a transparent face plate, a photoconductive target at said face plate having a surface receiving an image of a scene and constituted of material exhibiting a relatively low dark current, said target having a transparent signal plate beTween it and the face plate, means for scanning the opposite surface of said target with an electron beam thereby generating an electrical current corresponding to light variations in said said scene, said means including an electron gun for generating an electron beam remote from said target and means for deflecting the electron beam before it reaches said target and a tubular anode electrode having one end adjacent said opposite surface of the target and extending therefrom to adjacent said electron gun, said electrode having opening means therein spaced from said one end thereof, and means for illuminating said opposite surface of said target through said opening means and that portion of the tubular anode electrode lying between said opening means and said one end of the electrode to produce an artificial dark current for reducing build up and decay lag at low light level operating conditions, the improvement wherein: said means for illuminating comprises a light scattering surface on the inner surface of said portion of the tubular electrode lying between said target and said opening means, light source means disposed in spaced relation to said opening means and exteriorly of said electrode for illuminating said opposite surface of the target through said portion of the electrode as aforesaid, diffuser means located adjacent said opening means and extending circumferentially around said electrode for shielding said opening means from said light source means and for diffusing light emanating from said light source means prior to reaching said light scattering surface, and said opening means constituting means for admitting diffuse light from said diffuser means into the interior of said anode electrode substantially uniformly circumferentially therearound and inwardly of said light scattering surface whereby substantially uniformly to illuminate said opposite surface of the target.
Claim 2
Dependent Claim
343 words
In a television camera tube of the type comprising an evacuated envelope having a transparent face plate, a photoconductive target at said face plate having a surface receiving an image of a scene and constituted of material exhibiting a relatively low dark current, said target having a transparent signal plate beTween it and the face plate, means for scanning the opposite surface of said target with an electron beam thereby generating an electrical current corresponding to light variations in said said scene, said means including an electron gun for generating an electron beam remote from said target and means for deflecting the electron beam before it reaches said target and a tubular anode electrode having one end adjacent said opposite surface of the target and extending therefrom to adjacent said electron gun, said electrode having opening means therein spaced from said one end thereof, and means for illuminating said opposite surface of said target through said opening means and that portion of the tubular anode electrode lying between said opening means and said one end of the electrode to produce an artificial dark current for reducing build up and decay lag at low light level operating conditions, the improvement wherein: said means for illuminating comprises a light scattering surface on the inner surface of said portion of the tubular electrode lying between said target and said opening means, light source means disposed in spaced relation to said opening means and exteriorly of said electrode for illuminating said opposite surface of the target through said portion of the electrode as aforesaid, diffuser means located adjacent said opening means and extending circumferentially around said electrode for shielding said opening means from said light source means and for diffusing light emanating from said light source means prior to reaching said light scattering surface, and said opening means constituting means for admitting diffuse light from said diffuser means into the interior of said anode electrode substantially uniformly circumferentially therearound and inwardly of said light scattering surface whereby substantially uniformly to illuminate said opposite surface of the target.
Claim 3
Dependent Claim
24 words
A tube as claimed in claim 1 wherein the light scattering surface of said tubular electrode is chemically etched to provide light scattering properties.
Claim 4
Dependent Claim
21 words
A tube as claimed in claim 1 and wherein said tubular electrode is shot blasted to provide said light scattering properties.
Claim 5
Dependent Claim
58 words
A tube as claimed in claim 1 and wherein the tubular anode electrode has a reduced tapered portion along its length distant from its end adjacent the target electrode and between two portions of different cross-sectional dimensions, said means for admitting diffuse light into the tubular anode comprising a ring of holes provided in said reducing tapered portion.
Claim 6
Dependent Claim
40 words
A tube as claimed in claim 4 and wherein said diffuser means comprises a ring of light diffusing material surrounding the portion of the tubular anode electrode of smaller cross-sectional dimensions and shielding the holes provided in said tapered portion.
Claim 7
Dependent Claim
59 words
A tube as claimed in claim 1 and wherein said tubular anode electrode comprises a first portion adjacent said target and a second portion remote from said target, said second portion being of smaller cross-sectional dimension than said first portion, said diffuser means comprising a light diffusing ring occupying a space between said portions of the tubular anode electrode.
Claim 8
Dependent Claim
17 words
A tube as claimed in claim 5 whereis said light diffusing ring is of ground fused silica.
Claim 9
Dependent Claim
17 words
A tube as claimed in claim 6 wherein said light diffusing ring is of ground fused silica.
Claim 10
Dependent Claim
43 words
A tube as claimed in claim 5 and wherein the reduced tapered portion of the tubular electrode is perforated by a plurality of small holes and the diffuser ring is rendered less light transmissive in places seen by the centre of the target.
Claim 11
Dependent Claim
24 words
A tube as claimed in claim 9 and wherein said diffuser ring is rendered less light transmissive in said places by thin metal coatings.
Claim 12
Dependent Claim
14 words
A tube as claimed in claim 10 wherein said metal coatings are of aluminium.
Claim 13
Dependent Claim
106 words
A tube as claimed in claim 1 and wherein said tubular anode electrode includes a perforated flat metal disc arranged perpendicularly tO the axis of the tube and defining said opening means, said electrode having a portion of large cross-sectional dimension and a portion of small cross-sectional dimension and said disc extending between such portions, said diffuser means being in the form of a ring of light diffusing material surrounding the portion of the tubular anode electrode of smaller cross-sectional dimension shielding the holes in said perforated flat metal disc, which ring is rendered less light transmissive in places seen by the centre of the target.
Claim 14
Dependent Claim
83 words
A tube as claimed in claim 12 and wherein said perforated flat metal disc is spaced from the diffuser ring such that the ratio of this spacing to the diameter of the holes in the metal disc is twice the ratio of the spacing between the target and the metal disc to the target diameter, the metallisation of the diffuser ring being such that the centre of the target sees only metallised areas whilst the extremities of the target sees only clear areas.
Claim 15
Dependent Claim
19 words
A tube as claimed in claim 1 in which said light source means is external of the tube envelope.
Claim 16
Dependent Claim
82 words
A tube as claimed in claim 14 and wherein said light source means comprises a plurality of small light bulbs around the neck of the tube, adjacent the gun section, the envelope of the tube including a frosted portion adjacent the mounting position of the plurality of bulbs and a frosted portion adjacent said ring of holes provided in said reduced tapered portion so that the tube envelope may act as a light guide transmitting light from said bulbs to said holes.
Claim 17
Dependent Claim
62 words
A tube as claimed in claim 14 wherein said tubular electrode has two portions of different cross-sectional dimensions and wherein a disc of metal is provided around said portion of the tubular anode electrode of smaller cross-sectional dimension on the cathode gun side of said first mentioned frosted portion of the tube envelope to reflect light therefrom towards said ring of holes.
Claim 18
Dependent Claim
21 words
A tube as claimed in claim 16 and wherein the reflecting surface of said metal disc facing said holes is matt.
Claim 19
Dependent Claim
19 words
A tube as claimed in claim 1 and wherein said light source means is internal of the tube envelope.
Claim 20
Dependent Claim
46 words
A tube as claimed in claim 18 and wherein said light source means is a light bulb, light from the bulb being conducted to the means for admitting light into said tubular anode electrode by at least one reflection from the wall of the tube envelope.
Claim 21
Dependent Claim
33 words
A tube as claimed in claim 19 and wherein the bulb within the tube envelope is arranged to be supplied with current via its own connection passing through the envelope of the tube.
Claim 22
Dependent Claim
28 words
A tube as claimed in claim 19 and wherein the bulb is connected in parallel with the cathode gun heater and is supplied via the same external connections.
Claim 23
Dependent Claim
60 words
A tube as claimed in claim 21 and wherein the portions of the tube envelope from which light is reflected during its passage from the bulb to the means for introducing light into the tubular anode electrode are covered with materials of different light reflecting properties whereby adjustment to the interior of the illumination provided may be made following manufacture.
Claim 24
Dependent Claim
52 words
A tube as claimed in claim 22 and wherein said materials of different light reflecting properties are provided as zones of white and black paint over the portions of the tube envelope from which light is reflected, the ratio of black to white being adjusted until a suitable dark current is achieved.
Claim 25
Dependent Claim
66 words
A tube as claimed in claim 1 wherein the tubular anode electrode has two portions of different cross-sectional dimensions and wherein the outer surface of the tube envelope between the region of reduction in the cross-sectional dimensions of the tubular anode electrode and the tube target is painted black in order to reduce the possibility of stray light reaching to said opposite surface of the target.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |