US2740918A - Cathode ray tubes - Google Patents

Cathode ray tubes Download PDF

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Publication number
US2740918A
US2740918A US261804A US26180451A US2740918A US 2740918 A US2740918 A US 2740918A US 261804 A US261804 A US 261804A US 26180451 A US26180451 A US 26180451A US 2740918 A US2740918 A US 2740918A
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US
United States
Prior art keywords
anode
electrode
tube
anode part
envelope
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
US261804A
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English (en)
Inventor
James Ivanhoe John Penfound
Stillwell Peter Frederic Cryer
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.)
EMI Ltd
Electrical and Musical Industries Ltd
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EMI Ltd
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Filing date
Publication date
Application filed by EMI Ltd filed Critical EMI Ltd
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Publication of US2740918A publication Critical patent/US2740918A/en
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    • 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
    • H01J31/38—Tubes with photoconductive screen, e.g. vidicon
    • 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

  • This invention relates to charge storage pick-up tubes and in particular to such tubes employed as television pick-up tubes of the type wherein an electron beam is arranged to scan a target electrode on which a charge image is formed corresponding to the scene to be televised and in which picture signals are generatedin a signal electrode capacitatively associated with the target electrode.
  • a wall anode for the purpose of producing a uniform accelerating field for the electrons, such wall anode being for example in the form of a conducting coating applied to the inner surface of the envelope of the tube.
  • the spurious signals are objectionable because they tend/to overload the amplifiers to which the output of the pickup tube is fed, and also were a device is provided which determines the absolute level of the television signals with reference to the level corresponding vto black during each line of the scanning raster, theV spurious signalsI interfere with the operation of said device.
  • the object of the present invention is to ⁇ provide a tube of the type referred to in which the pick-up of spurious signals by the signed plate is reduced.
  • an electric circuit arrangement including a pick-up tube comprising an envelope having therein a kcharge storage target electrode, a signal electrode associated with said storage electrode, an electron gun and an anode electrode system extending between said gun and said target electrode, said anode electrode system comprising first and second spaced annular parts, electro-magnetic deflecting means surrounding only the first anode part remote from said signal electrode, means for maintaining said anode parts atV a D.
  • Figure 1 illustrates a typical form of pick-up tube, provided with a two part anode according to the invention
  • Figure 5 is an enlarged view of the target electrode of the tubesshown in Figs. le4.
  • the glass envelope of the pickup tube compri-ses a tubular body portion 1 and an enlarged tubular end portion 2 which are joined together by means of a shoulder 3, a neck 4 being joined to the other end of the body portion 1 by means of a second shoulder 5.
  • the end of the enlarged end portion 2 is closed by sealing to it a flat glass window 6 and the end of the neck 4 sealed off by means of a contact carrying base 7.
  • an electron gun 8 of conventional form for generating a beam of electrons land at the other end
  • a charge storage target electrode 9 arranged close to the inner surface of the window 6.
  • the target electrode 9 may suitably comprise a thin sheet of mica or glass having onthe side facing the electron gun 8 a mosaic of photo-electric elements 9a, its reverse side being coated with a semi-transparent continuous layer of metal 9b which in operation of the tube forms the signal electrode.
  • au anode electrode system comprising first and second spaced annular parts 10 and 13, formed of graphite or metal.
  • care is taken to ensure that the coating does not extend over the surface of the shoulder 3 although if desired it may extend over the shoulder 5 and part way along the neck 4.
  • Contact is made to anode part 10 by means of an internal connecting lead 11 and contact pin 12.
  • the anode part 13 is arranged in the enlarged tubular portion 2 and extends away from the shoulder 3 along the internal wall in the direction of the target 9. Contact to this anode part 13 is made by means of a lead 14 sealed into the shoulder 3.
  • the tube is also provided with a decelerating electrode 15 formed as a coating on the wall of the envelope arranged so that it is close to the target 9, and with an ion trapping mesh 16 which may be directly connected to the anode part 13 inside the tube.
  • ak tube When such ak tube is mounted in a camera, it is surrounded by deecting coils 17 and a longitudinal focussing coil 18 mounted on a non-magnetic metal supporting cylinder 19 the cylinder 19 being maintained at earth potential.
  • the tube above described is similar to a conventional tube adapted to be operated with a lo-w velocity beam and operates in the same manner, but has an essential difference in that, the anode system comprisesl first and second spaced annular parts 10 and 13, the anode part 10 extending over the inner surface of the body portion 1 of the envelope, and the part 13 extending over part of the internal wall of the enlargedend portion 2, the part of the anode which would normally extend over the shoulder 3 of the envelope being omitted.
  • spurious signals are introduced into the part 10 of the wall anode system during the yback periods of ⁇ the scanning sequence by reason of the high voltage pulses generated in the deflecting coils upon the collapse of the current therein.
  • the direct capacity between the anode and the signal plate is substantially .reduced whereby introduction of spurious signals into the video signal is minimised.
  • the direct capacity between the portion of the anode part which in some instances extends over the shoulder 5 is very small and has noty been found to seriously interfere with the operation of the tube.
  • a substantial reduction inl pick-up of spurious Signals from the anode system 10 and V13 is achieved according to the invention by connecting the anode parts 10 and 13 in an as sociated electrical circuit so that'they are independent of each other as far as high frequency currents are concerned and are separately decoupled to earth. As shown, each anode part 10 and 13 is connected to a D. C. supply indicated by the positive sign and to earth through the condensers 23 and 23a.
  • This resistance 20 may be of the order of 50,000 ohms and may conveniently be provided by bridging the anode parts lll-and 13 across the shoulder 3 with a thin strip of high resistance material. gure the resistance 'coating is shown on the inside of the tube and such an arrangement simpliiies the construction but it is equally possible to seal separate contacts from the anode part 10 and anode part 13 through the shoulder 3 so that they are spacedl apart and then bridge these contacts by means of a resistance provided on the exterior of the tube. It will be understood that since the tube disclosed, operates with a low beam current the D. C.
  • a suitable positive D. C. potential for anode parts 10 and 13 is 200 volts.
  • the resistance 20 will provide a very high impedance to high frequency currents and therefore there is no danger of transferring the high frequency component o-f the anode part 10 to the anode part 13. l
  • this anode part 13 is decoupled to earth via a condenser as in Figure 1 and this condenser is formed by coating, the external portion 2 of the envelope over the area occupied by the anode part 13 with metal or graphite as illustrated at 21.
  • the envelope 1 forms the dielectric of the condenser and the coating 21 is connected to earth by contacting a spring strip. 22A secured to the metal cylinder19, supporting the focus vcoil 18.
  • the D. C. supply tothe anode part 10 is made by connecting the contact pin 12at the gun end of the tube to the positive terminal of a suitable source of supply and is in turn decoupled to earth for high frequencies via a condenser 23.
  • the anode part 13 is provided with a contact 13a whichprojects through the wall of the tube at any convenient position along the wall portion 2 or shoulder 3 and from this contact a strip conductor 24 is provided which extends along the outer wall of the tube to the front edge of the glass window 6.
  • the conductor 24 engages with a contact whereby it is connected to the positive terminal of a D. C. supply and, isfdecoupled as regards high frequency currents by means'of a condenser 25 one plate of which is connected to; earth.
  • Theiother anode part 10 is connectedva pine12' and decoupledto earth byv means of condenser 23 inthe same manner as.
  • an electrostatic screen 26 conforming to the shape of the tube may be arranged over the shoulder 3 so that it extends partly over the anode part 10 and completely over the anode part 13.
  • the screen 26 is maintained at earth potential and this may be achieved lby ensuring that it makes Contact with the cylinder 19 as by means of a springv strip 27.
  • the tube is constructed exactly as described with reference to Figure 1 and the D. C. supply to the anode part 13 is obtained by connecting a line wire lead 28 from the contact 14' along the wall of the tube to the contact 12. Since this lead passes adjacent to the scanning field it may be found necessary to enclose this wire in an electrostatic screen maintained at earth potential.
  • an ion trapping mesh 16 forms an electrostatic screen between the target electrode 9 and the anode part 10 and thereby assists in the reduction of ode electrode and the signal plate with tubes having a' two-part'anode electrode system is shown by the following experimental results.
  • a tube having a wall anode extending over the body and the enlarged end portion and over the shoulder of the envelope, and provided with an ion trap mesh connected to the wall anode, and having l a deceleratingI electrode connected to ground via a condenser it was found that the capacity between the wall anode and the signal electrode was 1.0 nnF.
  • the capacityv was less than 0.002 ,4r/LF.
  • the capacity was 0.018 WLF.
  • An electric circuit arrangement including a pickup tube comprisingr an envelope having therein a charge storage target electrode, a signal electrode associated with said; storage electrode, an electron gun, an anode electrode system extending between said gun and said target electrode, said anode electrode system comprising rst and second spaced annular parts, electro-magnetic deflecting means surrounding only the rst anode part remote from said signal electrode, means for maintaining said anode'parts at a D. C. potential, and means for maintaining said second anode part which is nearer to said ⁇ signal electrode at earth potential for high frequencies', ⁇
  • An electric circuit arrangement including a contact element passing through said envelope and the space between said anode parts, a contact element at the gun end of said tube, and a lead extending along the exterior of said envelope connected to said two contact elements, said iirst anode part being also connected to said contact element at the gun end of said tube.
  • An electric circuit arrangement according to claim 1 including a grid electrode extending transversely across said tube and connected directly to said second anode part.
  • An electric circuit arrangement including a pick-up tube comprising an envelope having a shoulder portion connecting one smaller portion of the envelope to an enlarged portion thereof, a charge storage target electrode in the enlarged portion of said envelope, a signal electrode associated with said storage electrode, an electron gun in the smaller portion of said envelope, an anode electrode system extending between said" gun and said target electrode, said anode electrode system comprising rst and second spaced annular parts with the iirst anode part in the smaller portion of the envelope and terminating at a point coinciding substantially with the commencement of said shoulder and the second anode part arranged in said enlarged portion, electro-magnetic deflection means sur rounding only the rst anode part in the smaller portion of said envelope, means for maintaining said anode sys tem parts at a D.
  • An electric circuit arrangement including an electric contact element passing through said shoulder and connected to said second anode part arranged in said enlarged portion, and separate connections to said rst anode part and to said contact element connecting said parts to a source of D. C. potential and separate capacities for maintaining said separate anode parts at earth potential for high frequencies.
  • An electric circuit arrangement including a pick-up tube comprising an envelope having therein a charge storage target electrode, a signal electrode associated with said storage electrode, an electron gun, an anode electrode system extending between said gun and said target electrode, said anode electrode system comprising rst and second spaced annular parts, electro-magnetic deilecting means surrounding only the first anode part remote from said signal electrode, a high resistance interconnecting said two anode parts, means for connecting said iirst anode part to a source of D.
  • An electric circuit arrangement including a pick. up tube comprising an envelope having therein a charge storage target electrode, a signal electrode connected with said target electrode, an electron gun, an anode electrode system extending between said gun and said target electrode, said anode electrode system comprising rst and second spaced annular. parts, electro-magnetic deflecting means surrounding only the irst anode part remote from said signal electrode, means for maintaining said anode parts at a D. C.
  • said last named means including a capacity formed by said second anode part, the dielectric of said envelope and a conductive covering surrounding said second anode part on the exterior of said envelope, whereby high frequency voltage fluctuations induced in said first-mentioned anode part from said deecting means are substantially prevented from reaching said second anode part so that the pick up of spurious high frequency signals by said signal electrodc from said anode system is substantially reduced.
  • An electric circuit arrangement including a conductive sheath enclosing said tube, and a contact element connecting said conducting sheath to said conductive covering.
  • An electric circuit arrangement including a pick-up tube comprising an envelope having therein a charge storage target electrode, a signal electrode associated with said storage electrode, an electron gun, an anode electrode system extending between said gun and said tar get electrode, said anode electrode system comprising rst and second spaced annular parts, electro-magnetic deflecting means surrounding only the first anode part remote from said signal electrode, means for maintaining said irst anode part at a D. C. potential, and separate means for maintaining said second anode part at a D. C.
  • said separate means including a connection from said second anode part through said envelope connected to a conductor provided on the exterior of said envelope to a position near to said signal electrode and a contact to engage said conductor near to said signal electrode, said contact being connected to earth through a condenser and to a source of D. C. potential, whereby high frequency voltage fluctuations induced in said first anode part from said deflecting means are substantially prevented from reaching said second anode part so that the pick-up of spurious high frequency signals by said signal electrode from said anode system is substantially reduced.

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  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US261804A 1950-12-16 1951-12-15 Cathode ray tubes Expired - Lifetime US2740918A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB30712/50A GB711275A (en) 1950-12-16 1950-12-16 Improved circuit arrangement employing cathode ray tubes

Publications (1)

Publication Number Publication Date
US2740918A true US2740918A (en) 1956-04-03

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ID=10311956

Family Applications (1)

Application Number Title Priority Date Filing Date
US261804A Expired - Lifetime US2740918A (en) 1950-12-16 1951-12-15 Cathode ray tubes

Country Status (5)

Country Link
US (1) US2740918A (de)
DE (1) DE944558C (de)
FR (1) FR1051489A (de)
GB (1) GB711275A (de)
NL (1) NL165997B (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2873398A (en) * 1956-01-04 1959-02-10 Munsey E Crost Direct viewing moving target indicator cathode-ray storage tube
US2875371A (en) * 1954-07-20 1959-02-24 Emi Ltd Arrangements embodying pick-up tubes
US2878416A (en) * 1953-08-10 1959-03-17 Pye Ltd Television camera tubes
US3303278A (en) * 1964-05-13 1967-02-07 Tesla Np Television pick-up camera for three color pick-up of television images
US4658182A (en) * 1983-05-12 1987-04-14 Sony Corporation Image pick-up tube

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1292173B (de) * 1963-09-07 1969-04-10 Fernseh Gmbh Justiereinrichtung in einem Ablenksystem fuer Fernsehaufnahmeroehren u. dgl.

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2322807A (en) * 1940-12-28 1943-06-29 Rca Corp Electron discharge device and system
US2404046A (en) * 1941-06-21 1946-07-16 Rca Corp Television transmitting apparatus
US2548118A (en) * 1950-05-01 1951-04-10 Rca Corp Art of analyzing optical images
US2555091A (en) * 1948-02-03 1951-05-29 Emi Ltd Cathode-ray tube
US2579351A (en) * 1949-08-30 1951-12-18 Rca Corp Isocon pickup tube

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR825557A (fr) * 1936-08-13 1938-03-07 Dispositif collecteur d'images de télévision à tube accumulateur d'images
DE896055C (de) * 1936-08-13 1953-11-09 Walter Heimann Dr Ing Anordnung zur Verminderung von den Nutzbildimpulsen ueberlagerten niederfrequenten Stoerimpulsen beim Kathodenstrahlabtaster
DE702243C (de) * 1936-09-10 1941-02-03 Walter Heimann Dr Ing Verfahren zur Verringerung bzw. Beseitigung des bei speichernden Fernsehsenderoehren auftretenden Stoerimpulses
DE742002C (de) * 1939-03-30 1943-11-20 Bosch Gmbh Robert Roehrensender
DE742802C (de) * 1940-09-03 1943-12-11 Fernseh Gmbh Speichernde Bildzerlegerroehre mit eingebautem Sekundaerelektronenvervielfacher und einem die erste Prallstufe darstellenden, vor der Speicherelektrode angeordneten Rahmen oder Ring

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2322807A (en) * 1940-12-28 1943-06-29 Rca Corp Electron discharge device and system
US2404046A (en) * 1941-06-21 1946-07-16 Rca Corp Television transmitting apparatus
US2555091A (en) * 1948-02-03 1951-05-29 Emi Ltd Cathode-ray tube
US2579351A (en) * 1949-08-30 1951-12-18 Rca Corp Isocon pickup tube
US2548118A (en) * 1950-05-01 1951-04-10 Rca Corp Art of analyzing optical images

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878416A (en) * 1953-08-10 1959-03-17 Pye Ltd Television camera tubes
US2875371A (en) * 1954-07-20 1959-02-24 Emi Ltd Arrangements embodying pick-up tubes
US2873398A (en) * 1956-01-04 1959-02-10 Munsey E Crost Direct viewing moving target indicator cathode-ray storage tube
US3303278A (en) * 1964-05-13 1967-02-07 Tesla Np Television pick-up camera for three color pick-up of television images
US4658182A (en) * 1983-05-12 1987-04-14 Sony Corporation Image pick-up tube

Also Published As

Publication number Publication date
DE944558C (de) 1956-06-21
FR1051489A (fr) 1954-01-15
NL165997B (nl)
GB711275A (en) 1954-06-30

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