US2622226A - Television pickup tube - Google Patents
Television pickup tube Download PDFInfo
- Publication number
- US2622226A US2622226A US163658A US16365850A US2622226A US 2622226 A US2622226 A US 2622226A US 163658 A US163658 A US 163658A US 16365850 A US16365850 A US 16365850A US 2622226 A US2622226 A US 2622226A
- Authority
- US
- United States
- Prior art keywords
- photo
- electrons
- storage surface
- tube
- storage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
- H01J29/021—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof arrangements for eliminating interferences in the tube
Definitions
- the present invention relates to television pick-up tubes of the kind employing high velocity scanning, such as of the types known as iconoscopes and image iconoscopes.
- Such tubes suffer from various disadvantages, particularly the generation of spurious signals, insufiicient collection by the collector electrode of the tube of secondary electrons emitted from the storage surface of the tube, and redistribution effects 'due to secondary electrons emitted from the storage surface being redistributed over that surface. It is known to improve the operation of such tubes by irradiating the inside of the tube with a biasing light, and this method is already practiced with tubes of the iconoscope type.
- This collection of photo-electrons by the storage surface tends to equalize the non-uniformity of the redistribution of the secondary electrons over the storage surface, and also tends to reduce the effect known as flare, by tending to neutralize the positive charge resulting from the scanning on the bottom zone of the storage surface.
- the efliciency of the improvement obtained in this way is very low because only a small part of the photo-electrons released by the biasing light can reach the storage surface, owing to their low initial velocity.
- the present invention has for its object to increase the efliciency of the improvement obtained by irradiating the tube with a bias light, and consists in the provision of means for accelerating towards the storage surface the photoelectrons released from the irradiated photosensitive Wall coating or surface, whereby a greater proportion of the released photo-electrons can reach the storage surface.
- the acceleration should be such that the photoelectrons will reach the storage surface with a relatively low velocity so that they are able to charge that surface negatively.
- the invention also consists in a television 2 pick-up tube of the kind employing high velocity scanning, in which a photo-sensitive surface is provided adjacent the storage surface, together with means for illuminating the photosensitive surface, and wherein the collector electrode for collecting the secondary electrons released from the storage surface is interposed between the latter and the photo-sensitive surface and is arranged to be maintained at a positive potential relatively to the photo-sensitive surface.
- the collector electrode is perforated, so that the photo-electrons released from the photo-sensitive surface reach the storage surface through the perforations in the collector electrode and are accelerated towards the storage surface by reason of the collector electrode being maintained at a more positive potential than the photo-sensitive layer.
- the pick-up tube comprises an evacuated envelope I containing a semi-transparent photo-cathode 2 adjacent one end of the tube and a storage target spaced therefrom and arranged parallel to the photocathode 2.
- the target may comprise a mica sheet 3, of which the surface facing the photocathode 2 constitutes the storage surface of the target. That surface may be coated with a material to make it highly secondary emissive.
- the sheet 3 is backed with a continuous conductive layer 4 forming the signal plate which is connected externally of the envelope l to a load resistor 5, across which the signal potentials are developed and fed into a signal preamplifier.
- Photo-electrons released from the photo-cathode 2 under the influence of an optical image projected thereon are accelerated towards the storage surface 3 by the Wall coating 1 which is maintained at a positive potential by connection to a source of potential such as battery l3, and are focussed upon the storage surface by the field of an image focussing coil 8 surrounding the envelope 1.
- the storage surface 3 is scanned in a line raster by a high velocity beam generated by an electron gun 6 in an inclined side tube l' of the main envelope l', the side tube I being surrounded by the necessary coils l4 and I5 for focussing and deflecting the beam.
- a collector electrode 9 is arranged in the envelope l for collecting secondary electrons emitted from the storage surface 3 both by the incident primary photo-electrons from the photo-cathode 2 and by the incident electrons from the scanning beam.
- the construction and mode of operation of the tube as so far described is conventional and well known in the art.
- the collector electrode 9 is usually in the form of an internal conducting coating on the wall of the envelope l
- the collector electrode 9 is constructed of a coarse mesh conductor which is of cylindrical shape and is mounted surrounding the storage surface 3 and spaced a small distance from the internal surface of the envelope l which is coated with a photo-sensitive layer Ill.
- the latter is irradiated by a light source ll, shown provided outside the envelope I.
- the source ll may be of annular form surrounding the envelope I and layer IE3, or an annular array or group of light sources may be similarly arranged. Precaution must be taken to avoid light from the source H from falling onto the photo-cathode 2, in order to avoid any additional noise component.
- the source H is preferably provided with suitable means such as a shield or light guides [2 or the like in order to confine the illumination to the photo-sensitive layer IO.
- a potential difference is maintained between the mesh 8 and the photo-sensitive layer It, so that the mesh is positive with respect to the photo-sensitive layer and accelerated photo-electrons emitted from the irradiated layer In.
- the value of this potential difference (which may, for example, be 5-8 volts) is within the range for which the secondary emission ratio of the storage surface 3 will be less than unity; that is to say, photo-electrons from the irradiated layer impinge upon the storage surface 3 with such velocities that the ratio of the number of secondary electrons released from the storage surface to the number of arriving photo-electrons is less than unity, whereby the storage surface is negatively charged.
- the mesh aperture of the electrode 9 and the distance between it and the photo-sensitive layer 10 are made of suitable values to produce a small field penetration factor, so that the equilibrium potential of the storage surface 3 resulting from the scanning is mainly determined by the mesh potential.
- sufficient photo-electrons must be capable of penetrating through the mesh 9 and landing on the storage surface in order to produce the wanted negative charge.
- The. photo-emission from the photo-sensitive layer It] may be made non-uniform, for example, by illuminating the layer i0 non-uniformly along its length as shown by the position of source H or along its circumference, in order to obtain the desired charging of the storage surface.
- the illumination may be more intense at the zone of the layer H] which will irradiate the bottom zone of the storage surface 3 with photo-electrons, in order to compensate for flare.
- the photo-sensitive layer in may be only intermittently illuminated, for example, .during only the fiyback periods of the scanning beam, preferably the frame flyback periods, so that the storage surface will be charged negatively only during these flyback periods.
- This intermittent illumination may be effected by obturating the light source H by rotating or vibrating shutters or similar devices.
- a shutter l6 may be rotated by motor I! and drive shaft l8 alternatively, as the light source, one or more cathode ray tubes or gas discharge tubes may be employed, the light output of which can be pulsed and controlled by feeding thereto suitable voltage or current pulses to operate the tube or tubes during the flyback periods.
- the invention may be applied similarly to a tube of the iconoscope type, the photoelectrons from the layer [U in that case irradiating the photo-sensitive mosaic target of the iconoscope instead of the secondary emitting target of the image iconoscope.
- a charge storage surface capable of storing energy in the form of a charge pattern corresponding to the light distribution in an optical image
- a source of photo-electrons in the vicinity of said surface adapted to release photo-electrons in that vicinity, means for illuminating said source to cause it to release photo-electrons
- a collector electrode in the vicinity of saidstorage surface for collecting electrons released from said storage surface, said collector electrode being disposed between said source and said storage surface, and means for maintaining said collector electrode at a positive potential relatively to said source for accelerating photoelectrons released from said .source towards said storage surface.
- a charge storage surface capable of storing energy in the form of a charge pattern corresponding to the light distribution in an optical image,.of .
- a source of photo-electrons in the vicinity of said surface adapted to release photo-electrons in that vicinity, means for illuminating said source to cause it to release photo-electrons, a collector electrode in the vicinity of said storage surface for collecting electrons released from said storage surface, said, collector electrode being interposed between said source and said storage sur-- face and being of perforate construction to allow photo-electrons released from said source to pass through said electrode, and means for maintaining said collector electrode at a positive potential relatively to said source for accelerating photoelectrons released from said source towards said storage surface.
- a television pick-up tube comprising an evacuated envelope having within it a photocathode upon which a light image is adapted to be directed to release photo-electrons from said photo-cathode, a target spaced from said photo cathode and comprising a secondary electron emitting storage surface facing said photo-cathode and forming elemental condensers with a signal plate backing said storage surface, means for accelerating and focussing photo-electrons released from said photo-cathode to impact upon said storage surface whereby to eject secondary electrons from said surface to form a charge pattern thereon corresponding to the light distribution in the light image, means for scanning said surface with a high velocity electron beam to discharge said surface to equilibrium potential, a collector electrode in the vicinity of said surface for collecting secondary electrons emitted from said surface, a photo-electric surface in the vicinity of said storage surface for releasing photo-electrons towards said storage surface, means for illuminating said photo-electric surface to cause it to emit photo-electrons, and means for accelerating
- a television pick-up tube comprising an evacuated envelope having within it a photocathode upon which a light image is adapted to be directed to release photo-electrons from said photo-cathode, a target spaced from said photocathode and comprising a secondary emitting storage surface facing said photo-cathode and.
Landscapes
- Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB27352/49A GB688904A (en) | 1949-10-25 | 1949-10-25 | Improvements in or relating to television pick-up tubes |
Publications (1)
Publication Number | Publication Date |
---|---|
US2622226A true US2622226A (en) | 1952-12-16 |
Family
ID=10258206
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US163658A Expired - Lifetime US2622226A (en) | 1949-10-25 | 1950-05-23 | Television pickup tube |
Country Status (5)
Country | Link |
---|---|
US (1) | US2622226A (fr) |
DE (1) | DE866802C (fr) |
FR (1) | FR1019095A (fr) |
GB (1) | GB688904A (fr) |
NL (2) | NL76663C (fr) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2735035A (en) * | 1953-07-08 | 1956-02-14 | Television pick-up tubes and transmitting | |
US2738440A (en) * | 1950-12-06 | 1956-03-13 | Pye Ltd | Television pick-up tubes and television transmitting apparatus incorporating the same |
US2748312A (en) * | 1954-11-19 | 1956-05-29 | Hughes Aircraft Co | Cathode-ray storage tube system |
US2757233A (en) * | 1951-09-29 | 1956-07-31 | Emi Ltd | Electron discharge tube arrangements |
US2765422A (en) * | 1951-11-19 | 1956-10-02 | Itt | Television camera tube |
US2774814A (en) * | 1951-05-02 | 1956-12-18 | Hartford Nat Bank & Trust Co | Post-deflection horizontal color stripe pick-up tube |
US2805359A (en) * | 1951-10-11 | 1957-09-03 | Pye Ltd | Television pick-up tubes and television apparatus incorporating the same |
US2875360A (en) * | 1953-05-25 | 1959-02-24 | Westinghouse Electric Corp | Image intensifier |
US2875371A (en) * | 1954-07-20 | 1959-02-24 | Emi Ltd | Arrangements embodying pick-up tubes |
US2992358A (en) * | 1954-03-03 | 1961-07-11 | Itt | Radiation translating device |
US3014148A (en) * | 1958-04-21 | 1961-12-19 | United Aircraft Corp | Infrared photo-imaging device |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE948614C (de) * | 1952-11-25 | 1956-09-06 | Fernseh Gmbh | Bildspeicherroehre, bei der die Speicherelektrode mit langsamen Elektronen berieseltwird |
BE529088A (fr) * | 1953-05-25 | |||
DE1173513B (de) * | 1962-07-28 | 1964-07-09 | Fernseh Gmbh | Verfahren und Anordnung zur Aufnahme von Fernsehbildern mit Speicherroehren |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2324534A (en) * | 1941-09-30 | 1943-07-20 | Bell Telephone Labor Inc | Television transmitter |
US2360663A (en) * | 1941-02-28 | 1944-10-17 | Rca Corp | Electrical biasing means |
US2368884A (en) * | 1942-08-21 | 1945-02-06 | Rca Corp | Television transmitting apparatus |
US2378857A (en) * | 1943-01-16 | 1945-06-19 | Farnsworth Television & Radio | Visual indicating system |
US2451005A (en) * | 1946-08-30 | 1948-10-12 | Rca Corp | Cathode-ray storage tube apparatus and method of operation |
-
0
- NL NL737300857A patent/NL154166B/xx unknown
- NL NL76663D patent/NL76663C/xx active
-
1949
- 1949-10-25 GB GB27352/49A patent/GB688904A/en not_active Expired
-
1950
- 1950-05-23 US US163658A patent/US2622226A/en not_active Expired - Lifetime
- 1950-05-26 FR FR1019095D patent/FR1019095A/fr not_active Expired
- 1950-10-21 DE DEC3310A patent/DE866802C/de not_active Expired
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2360663A (en) * | 1941-02-28 | 1944-10-17 | Rca Corp | Electrical biasing means |
US2324534A (en) * | 1941-09-30 | 1943-07-20 | Bell Telephone Labor Inc | Television transmitter |
US2368884A (en) * | 1942-08-21 | 1945-02-06 | Rca Corp | Television transmitting apparatus |
US2378857A (en) * | 1943-01-16 | 1945-06-19 | Farnsworth Television & Radio | Visual indicating system |
US2451005A (en) * | 1946-08-30 | 1948-10-12 | Rca Corp | Cathode-ray storage tube apparatus and method of operation |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2738440A (en) * | 1950-12-06 | 1956-03-13 | Pye Ltd | Television pick-up tubes and television transmitting apparatus incorporating the same |
US2774814A (en) * | 1951-05-02 | 1956-12-18 | Hartford Nat Bank & Trust Co | Post-deflection horizontal color stripe pick-up tube |
US2757233A (en) * | 1951-09-29 | 1956-07-31 | Emi Ltd | Electron discharge tube arrangements |
US2805359A (en) * | 1951-10-11 | 1957-09-03 | Pye Ltd | Television pick-up tubes and television apparatus incorporating the same |
US2765422A (en) * | 1951-11-19 | 1956-10-02 | Itt | Television camera tube |
US2875360A (en) * | 1953-05-25 | 1959-02-24 | Westinghouse Electric Corp | Image intensifier |
US2735035A (en) * | 1953-07-08 | 1956-02-14 | Television pick-up tubes and transmitting | |
US2992358A (en) * | 1954-03-03 | 1961-07-11 | Itt | Radiation translating device |
US2875371A (en) * | 1954-07-20 | 1959-02-24 | Emi Ltd | Arrangements embodying pick-up tubes |
US2748312A (en) * | 1954-11-19 | 1956-05-29 | Hughes Aircraft Co | Cathode-ray storage tube system |
US3014148A (en) * | 1958-04-21 | 1961-12-19 | United Aircraft Corp | Infrared photo-imaging device |
Also Published As
Publication number | Publication date |
---|---|
NL76663C (fr) | |
GB688904A (en) | 1953-03-18 |
NL154166B (nl) | |
FR1019095A (fr) | 1953-01-16 |
DE866802C (de) | 1953-02-12 |
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