[go: up one dir, main page]

US2304091A - Signal-generating system - Google Patents

Signal-generating system Download PDF

Info

Publication number
US2304091A
US2304091A US314573A US31457340A US2304091A US 2304091 A US2304091 A US 2304091A US 314573 A US314573 A US 314573A US 31457340 A US31457340 A US 31457340A US 2304091 A US2304091 A US 2304091A
Authority
US
United States
Prior art keywords
target
electrons
electron
signal
scanning
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
Application number
US314573A
Other languages
English (en)
Inventor
Rudolf C Hergenrother
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems Aerospace Inc
Original Assignee
Hazeltine Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hazeltine Corp filed Critical Hazeltine Corp
Priority to US314573A priority Critical patent/US2304091A/en
Priority to DEH5935D priority patent/DE908864C/de
Priority to FR869218D priority patent/FR869218A/fr
Priority to GB2220/41A priority patent/GB546305A/en
Application granted granted Critical
Publication of US2304091A publication Critical patent/US2304091A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/48—Tubes with amplification of output effected by electron multiplier arrangements within the vacuum space
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/28—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen
    • H01J31/34—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having regulation of screen potential at cathode potential, e.g. orthicon

Definitions

  • signal generators of either of the types mentioned above provide an output signal, the amplitude of which is so minute as to necessitate a high degree of amplification to procure a useful signal.
  • Such amplification is difiicult to produce in conventional vacuum-tube amplifier circuits for the reason that the thermal noises associated with the vacuum tube are comparable in magnitude to the signal to be amplified.
  • Electron multipliers have heretofore been utilized in association with signal-generating cathode-ray tubes having a photosensitive target which is scanned by an electron beam of sumciently high velocity to provide a secondary-electron emission ratio at the target which is'greater than unity, in order to provide a signal output of relatively large amplitude without the disadvantages associated with the use of conventional vacuum-tub amplifler circuits. With such arrangements, it has been proposed to apply to the electron collector associated with the electron multiplier a suitable potential to attract the secondary electrons emitted by the photosensitive target during the scanning operation.
  • the collector electrode has a suitably high potential for emciently collecting electrons from the photosensitive target at a spot of restricted area, such potential would adversely affeet the scanning beam.
  • a cathode-ray signalgenerating tube including a photosensitive target which is scanned by electrons of sufficiently low velocity as to provide at the target a secondaryemission ratio of less than unity and which includes an electron collector associated therewith efiective to collect electrons at a spot of restricted area thereon and at a rate varying in accordance with the signal to be generated but having substantially no influence on the scanning beam.
  • an improved signal-generating system including a cathode-ray tube having a photosensitive target adapted to be scanned by an electron beam of sumciently low velocity as to provide a secondary-emission ratio of less than unity at the target.
  • It is a further object of the invention to pro vide an improved signal-generating system including a cathode-ray tube having a photosensitive target adapted to be scanned by an electron beam of sufllciently low velocity as to provide a secondary-emission ratio of less than unity and having associated therewith a suitable electron collector adapted to receive from the target an electron beam varying in accordance with the signal to be generated and having substantially no influence on the scanning beam.
  • a signalgenerating system comprises a cathode-ray signal-generating tube having a photosensitive tar- Means are provided for developing and accelerating toward the target electrode a beam of electrons of substantially constant intensity and having a velocity which is sumciently low at the target electrode as to provide a secondary-emission ratio of less than unity and for returning free electrons from the vicinity of the target, together with magnetic means for scanning the target in two directions normal to each other with the beam, whereby the number of electrons returning from the vicinity of each incremental area of the target, as such area is scanned by the beam,
  • means including a pair of beam-shifting plates adjacent the beam-developing means and having a spacing therebetween which is small relative to'the scanning deflections of the beam, and means including means for applying a steady unidirectional potential to the beam-shifting plates for directing, as an electron beam to a spot of restricted area on the electron collector, which spot is displaced from the first-named means in a predetermined direction, substantially all of the electrons returning from the vicinity of the target, whereby there is derived an output signal from the electron collector which varies in accordance 'with the number of electrons directed thereto.
  • the potential of the collector electrode and its arrangement in the tube are such that it does not impair the proper deflection of the electron beam.
  • the single figure of the drawing is a circuit diagram, partly schematic, of a television transmitting system including a video-frequency signal-generating system embodying the present invention.
  • the television transmitting system illustrated includes a conventional camera or projector Hi and a cathode-ray signal-generating unit ll having associated therewith an electron multiplier i 2 which may be of any suitable welllmown construction.
  • an electron multiplier i 2 which may be of any suitable welllmown construction.
  • the system includes a suitable timing and scanning signal generator Ill from which are derived suitable scanning fields for the signal generator II and suitable blanking and synchronizing signals for the transmitted television signal.
  • the signal generator H comprises an evacuated tube or envelope 22 having at one end thereof a suitable cathode or source of electrons 2! which, together with accelerating anodes 22 and 22, comprises an electron gun edective to generate a beam of relatively low-velocity electrons.
  • Anode 22' has a very small aperture therein so that the developed electron beam is of very small cross section.
  • a winding l9 surrounding the tube 22 and energized from a suitable source, such as a battery 22.
  • Magnetic scanning fields for deflecting the cathode-ray beam in each of two directions normal to each other are provided by scanning windings 2t, 2t and 26, 26, respectively, disposed successively along the tube and having their axes normal to each other, as shown in the drawing, or superposed so that one set of windings encloses the other.
  • Target 22 preferably comprises a photosensitive mosaic deposited on a thin insulating sheet 2 on the opposite side of which is a grounded metallic coating or backing plate 9.
  • a grounded metallic coating is provided on the inner surface of the tube between the electron gun and target 22.
  • beam-shifting plates 21, 28 having a fixed potential difierence applied therebetween from taps onbattery 22.
  • Plates 2?, 22 have a spacing therebetween which is small relative to the scanning deflections of the beam.
  • Electron multiplier I 2 has an opening adjacent cathode 2
  • an image of the scene to be transmitted is projected by camera It on the photosensitive surface of target electrode 22 in order to develop a video-frequency signal output from electron multiplier l2 which varies in accordance with variations in illumination from point to point of the target as it is scanned.
  • the video-frequency signal output of the electron multiplier I2 is amplified in video-frequency amplifier l2 and mixed therein with the synchronizing signals and the blanking signals to be transmitted.
  • the composite signal output of the video-freuuency amplifier and mixer It is utilized to modulate a suitable carrier wave in oscillatormodulator H, the modulated-carrier signal being thereafter amplified in radio-frequency amplifier l5 and supplied to transmitting system It, H for radiation.
  • a beam of electrons of substantially constant intensity and having a velocity which is sumclently low as to provide a secondary-emission ratio of less t unity at the target electrode 22 is (11- rected thereto by means of the magnetic field developed by winding iii. In the absence of all deflect potentials, such electron beam would follow in a tight spiral the lines ofjforce ofthe his it from the aperture in accelerating anode 22' to the target electrode 22.
  • the acceleratt anodes 2t and 22' having apertures therein, are, therefore, included in a means for accelerating as well as in a means for developing and accelerating toward .
  • the target electrode 22 a beam of electrons which is perpendicular to the plane of the target.
  • the beam is first deflected in one direction by means of the field developed by windings 2t, 2t and is then deflected in another direction at right angles thereto by means of the field developed by windings 2t, 2t and is thus edective to scan the target electrode 22 in a held or series of parallel lines.
  • the electron beam from the aperture in the accelerating anode 22' is deflected in two directions normal to each other and is at all times incident upon target electrode 22 substantially perpendicular thereto so as to prevent deiocusing of the beam.
  • the operating potentials oi the tube are so adjusted that the velocity of the scanning beam is very small near the surface of target electrode 22; that is, so that the seconda'ry-electron emission ratio from target 22 is less than unity. Under these conditions, and under a condition of equilibrium when none oi the electrons of the scanning beam is utilized to neutralize a charge on the target, the target is substantially at the potential of the cathode.
  • a suitable deflecting potential upon plates 22 and 28 which is efiective to displace the electron beam coming from cathode 2
  • the electron collector is of a restricted area. Therefore, the returning electrons are directed to the aperture in the electron collector 29 of electron multiplier l2 after which electron multiplication may be eflected in conventional manner. That is, a means is provided for directing, as an electron beam to a spot of restricted area on the electron collector 29, substantially all of the electrons which leave the target 22 and, inasmuch as the number of electrons which return from the vicinity of each incremental area of the target 22 as such area is scanned by the beam is determined only by the charge of such area, the
  • intensity of the returning electron beam at electron collector 29 varies in accordance with variations of illumination of the successive incremental areas of the target 22 and is representative of the signals to be generated.
  • shading efiects and lack of sensitivity accompanying the use of a scanning beam of sumciently high voltage to produce a secondaryelectron emission ratio of greater than unity at the target are avoided while the potential of the collector electrode 29 approximates that of anode 22' so that its eflect on the scanning beam is negligible.
  • a signal-generating system comprising, a cathode-ray signal-generating tube having a photosensitive target electrode and an electron collector, means for developing and accelerating toward said target electrode a beam of electrons of substantially constant intensity and having a velocity which is sufficiently low at said target electrode as to provide a secondary-emission ratio of less than unity and for returning free electrons from the vicinity of said target, magnetic means for scanning said target in two directions normal to each other with said beam, whereby the number of electrons returning from the vicinity of each incremental area of said target as such area is scanned by said beam is determined primarily by the charge of such area due to an image.
  • means including a pair of beamshifting plates adjacent said beam-developing means and having a spacing therebetween which is small relative to the scanning deflections of said beam, and means including means for applying a steady unidirectional potential to said beam-shifting plates for directing as an electron beam to a spot of restricted area on said electron collector, which spot is displaced from said first-named means in a predetermined direction, substantially all of the electrons returning from the vicinity of said target, whereby an output signal may be derived from said electron collector which varies in accordance with the number of electrons directed thereto.
  • a signal-generating system comprising, a cathode-ray signal-generating tube having a photosensitive target electrode and an electron collector, means for developing and accelerating toward said target a of electrons of substantially constant intensity, which is perpendicular to the plane oi.
  • said target which has a velocity which is sumciently low at said target electrode as to provide a secondary-emission ratio of less than unity, and for returning free electrons from the vicinity of said target
  • magnetic means for scanning said target electrode in two directions normal to each other with said beam whereby the number of electrons returning from the vicinity of each incremental area of said target as such area is scanned by said beam is determined primarily by the charge of such area due to an image projected thereon and suchreturning free electrons travel back through said magnetic means along substantially the same path as that traversed through said magnetic means by said scanning beam
  • means including a pair of beam-shifting plates adjacent said beam-developing means and having a spacing therebetween which is small relative to the scan ning deflections of said'beam, and means including means for applying a steady unidirectional potential to said beam-shifting plates for directing as an electron beam toa spot on said electron collector, which spot is displaced from said first-named means in a predetermined direction, substantially all of the electrons returning from the vicinity of said target
  • a signal-generating system comprising, a cathode-ray signal-generating tube having a photosensitive target electrode, an electron collector of a restricted area and a source oi electrons adjacent said collector, means for accelerating toward said target. electrode a beam of electrons from said source of substantially constant intensity andhaving a velocity which is sufiiciently low at said target electrode as to provide a secondary-emission ratio of less than unity and for returning free electrons from the vicinity of said target, magnetic means for scanning said target in .two directions normal to each other with said beam, whereby the number of electrons returning from the vicinity of each incremental area of said target as such area is scanned by said beam is determined primarily by the charge of such area due to an image projected thereon and such returning free electrons travel back through said magnetic means along substantially the same path as that traversed through said magnetic means by said scanning beam, means including a pair of beam-shifting plates adjacent said accelerating means and having a spacing therebetween which is small relasoaoci.
  • means including means for applying a a unidirectional potential to said beam-shifting plates for directing as an electron beam to a spot of restricted area on said electron collector, which spot is displaced from said first-named means in a predetermined direction, substantially all of the electrons returning from the vicinity of said target, whereby an output signal may be derived from said electron collector which varies in accordance with the number of electrons directed thereto.
  • a signal-generating system comprising, a cathode-ray signal-generating tube having a photosensitive target electrode, means for developing and accelerating toward said target electrode a beam of electrons of substantially constant intensity and having a velocity which is sumciently low at said target electrode as to provide a secondary-emission ratio of less than unity and for returning free electrons from the vicinity of said target, magnetic means for scanning said target electrode in two directions normal to each other with said beam, whereby the number of electrons returning from the vicinity of each incremental area of said target as such area is scanned by said beam is determined primarily by the charge of said area due to an image projected thereon and such returning free electrons travel back through said magnetic means along substantially the same path as that traversed through said magnetic means by said scanning beam, an electron multiplier associated with said tube and including an electron collector, means including a pair of beam-shifting plates adjacent said beam-developing means and having a spacing therebetween which is small relative to the scanning deflections of said beam, and means including means for applying a steady unidirectional potential to
  • a signal-generating system comprising, a cathode-ray signal-generating tube having a photosensitive target electrode and a source of low-velocity electrons therein, means for developing and accelerating toward said target electrode a beam of electrons from said source of substantially constant intensity which has a velocity suiilciently low at said target electrode as to provide a secondary-emission ratio of less than unity and for returning free electrons from the vicinity of said target, magnetic means for deflecting electrons from said source in two directions normal to each other to scansaid target with said beam, whereby the number of elecative to the scanning deflections of said beam,
  • trons returning from the vicinity of each incremental area of said target as such area is scanned by said beam is determined primarily by the charge of such area due to an image projected thereon and such returning free electrons travel back through said magnetic means along substantially the same path as that traversed through said magnetic means by said scanning beam, an electron collector, means including a pair of beam-shifting plates adjacent said beamdeveloping means and having a spacing therebetween which is small relative to the scanning deflections of said beam, and means including means for applying a steady unidirectional potential to said beam-shifting plates for directing as an electron beam to a spot of restricted area on said electron collector, which spot is displaced from said first-named means in a predetermined direction, substantially all of the electrons returning from the vicinity of said target, whereby an output signal may be derived from said electron collector which varies in accordance with the number of electrons directed thereto.
  • a signal-generating system comprising, a cathode-ray signal-generating tube having a photosensitive target electrode and an electron collector, a source of low-velocity electrons in said tube, means for accelerating toward said target a beam of electrons from said source of substantially constant intensity and for returning free electrons from the vicinity of said target, the electrons of said beam having a velocity which is suihciently low at said target electrode as to provide a secondary-emission ratio of less than unity, means for developing a longitudinal magnetic field between said source and said target electrode, magnetic means for deflecting electrons from said source in two directions normal to each other to scan said target with said beam, whereby the number of electrons leaving each incremental area of said target as such area is scanned by said beam is determined primarily by the charge of such area due to an image projected thereon and such returning free electrons travel back through said magnetic means along substantially the same path as that traversed through said magnetic means by said scanning beam, means including a pair of beam-shifting plates adjacent said accelerating means and having a spacing therebetween
  • a signal-generating system comprising, a cathode-ray signal-generating tube having a photosensitive target electrode, an electron collector, and a source of electrons adjacent said collector, means for accelerating toward said.
  • target electrode a beam of electrons of substantially constant intensity which has a velocity sufiiciently low at said target electrode to provide a secondary-emission ratio of less than unity and for returning said beam to the vicinity of said source of electrons, means for developing a longitudinal magnetic field between said source and said target electrode, means including a.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US314573A 1940-01-19 1940-01-19 Signal-generating system Expired - Lifetime US2304091A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US314573A US2304091A (en) 1940-01-19 1940-01-19 Signal-generating system
DEH5935D DE908864C (de) 1940-01-19 1941-01-09 Bildsenderoehre
FR869218D FR869218A (fr) 1940-01-19 1941-01-14 Dispositif pour la production de signaux, en particulier pour les systèmes émetteurs de télévision
GB2220/41A GB546305A (en) 1940-01-19 1941-02-18 Cathode-ray tube systems for generating image signals

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US314573A US2304091A (en) 1940-01-19 1940-01-19 Signal-generating system

Publications (1)

Publication Number Publication Date
US2304091A true US2304091A (en) 1942-12-08

Family

ID=23220483

Family Applications (1)

Application Number Title Priority Date Filing Date
US314573A Expired - Lifetime US2304091A (en) 1940-01-19 1940-01-19 Signal-generating system

Country Status (4)

Country Link
US (1) US2304091A (fr)
DE (1) DE908864C (fr)
FR (1) FR869218A (fr)
GB (1) GB546305A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532793A (en) * 1944-12-30 1950-12-05 Rca Corp Reflex amplification utilizing camera tube
US2575477A (en) * 1949-06-29 1951-11-20 Rca Corp Pickup tube residual scanning eliminator
US2598612A (en) * 1948-12-30 1952-05-27 Times Facsimile Corp Modulating system and apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL302264A (fr) * 1962-12-20
DE1220886B (de) * 1964-01-18 1966-07-14 Fernseh Gmbh Ablenksystem fuer Vidikon- und Superorthikonkameras

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532793A (en) * 1944-12-30 1950-12-05 Rca Corp Reflex amplification utilizing camera tube
US2598612A (en) * 1948-12-30 1952-05-27 Times Facsimile Corp Modulating system and apparatus
US2575477A (en) * 1949-06-29 1951-11-20 Rca Corp Pickup tube residual scanning eliminator

Also Published As

Publication number Publication date
FR869218A (fr) 1942-01-27
DE908864C (de) 1954-04-12
GB546305A (en) 1942-07-07

Similar Documents

Publication Publication Date Title
US2544753A (en) Electron camera tube
US2433941A (en) Television transmitting tube
US2147760A (en) Television apparatus
US2404098A (en) Television transmitting system
US2462569A (en) Television receiving tube with storage properties
US2304091A (en) Signal-generating system
US2537250A (en) Electronic tube
US2339662A (en) Television transmitter
US2377972A (en) Television transmitting system
US2260911A (en) Television device
US2256462A (en) Television transmitting device
US2760096A (en) Television pickup tube
US2286280A (en) Electronic device
US2548405A (en) Electron tube
US2412086A (en) Image dissector tube
US2213177A (en) Television transmitting tube
US2853648A (en) Video storage tubes
US2256523A (en) Electron multiplier
US2619531A (en) Pickup tube for television and the like
US2875371A (en) Arrangements embodying pick-up tubes
US2822493A (en) Graphechon storage tube
US2292817A (en) Television system
US2563490A (en) Cathode arrangement fob television
US2520244A (en) Television pickup tube
US2556824A (en) Cathode-ray tube