US2544753A - Electron camera tube - Google Patents

Electron camera tube Download PDF

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Publication number
US2544753A
US2544753A US5009A US500948A US2544753A US 2544753 A US2544753 A US 2544753A US 5009 A US5009 A US 5009A US 500948 A US500948 A US 500948A US 2544753 A US2544753 A US 2544753A
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US
United States
Prior art keywords
electron
electrons
target
layer
tube
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
US5009A
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English (en)
Inventor
Robert E Graham
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.)
AT&T Corp
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Bell Telephone Laboratories Inc
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
Priority to NL79223D priority Critical patent/NL79223C/xx
Priority to BE486171D priority patent/BE486171A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US5009A priority patent/US2544753A/en
Priority to FR975726D priority patent/FR975726A/fr
Priority to GB2411/49A priority patent/GB711202A/en
Application granted granted Critical
Publication of US2544753A publication Critical patent/US2544753A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/39—Charge-storage screens
    • H01J29/44—Charge-storage screens exhibiting internal electric effects caused by particle radiation, e.g. bombardment-induced conductivity
    • 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
    • H01J31/36—Tubes with image amplification section, e.g. image-orthicon

Definitions

  • This invention relates to electro-optical devices and more particularly to electron camera tubes for television.
  • the bombarding particles penetrate the insulator, causing a disruptive separation of the positive and negative charges specific to the atoms which are affected by the bombarding particles. These charges are drawn toward the electrodes producing the electric field and this motion of charges constitutes a conduction current which is in many cases greatly in excess of the charge rate represented by the bombarding particles.
  • Diamond is a favored solid insulator for this work (although other materials such as, for example, others listed in the Wooldridge and McKay applications can also be used) because it can easily be obtained without sufficient impurities or imperfections to affect its high insulation resistance, or its conducting properties under bombardment.
  • the carbon atoms therein consist each of a nucleus inhibiting fixed units of positive change to which two electrons are tightly bound. This core is surrounded by four valence electrons. The carbon atoms are held together by electron pair bonds between a'd-f jacent atoms.
  • the insulation resistance is high because the electron bonds are very tight. As a result of this tightness, very few electrons are displaced from their bonds by thermal agitation. This is not the oazfe in, for example, metals, where a large number of electrons are continuously being displaced by thermal agitation and are relatively free to wander through the.
  • this localized electron deficiency is called a hole.
  • the hole Under an applied electric field, the arrangement of the electrons is changed, and the location of any given hole will change.
  • the hole can be conveniently regarded as a positive particle which is free to move under the infiuence of the field.
  • the electron freed from the bond in question constitutes a negative particle which is free to move under the influence of the electricfield.
  • a single bombarding electron may free a large number of electrons and positive holes, depending upon its impact energy. This large number of charged particles is then available for conduction current, so that considerable charge multiplication can be obtained.
  • any free electron or positive hole moves in accordance with thermal agitation and consequently has a completely random motion. Under an applied electric field, there is adirectional motion superimposed on the random one.
  • the order of mobility of the electrons in diamond is of the order of ,000 centimeters per second for a field of one volt per centimeter. Fora field of 10 volts per centimeter the velocity therefore is 10 centimeters per second. For a diamond crystal one millimeter thick, the transit time therefore is 10- seconds.
  • the mobility of the electrons is affected by the number of traps, that is the presence of foreign atoms or imperfections in the crystal. If an electron gets into a trap, it takes a greater or less amount of time to get out, depending upon the thermal energy required. Further information on traps and other characteristics of diamond crystals are given in the Wooldridge and McKay applications referred to above.
  • an electron. camera tube including an electron target embodyingv material which exhibits the property of electron bombardment induced conductivity.
  • Diamond is a preferred material for reasons given above. More specifically, the camera tube is generally similar to that type of commercial tube known as;the image orthicon and which is described in detail in an article by Messrs. Rose, Weim-er and Lawon page 424 of. the Journal of the Institute of Radio 3 Engineers for July 1946.
  • the camera tube of the present invention includes, however, a twosided mosaic comprising a mosaic layer of diamond or other crystals exhibiting the property of electron bombardment induced conductivity, the diamond layer being coated on one side with a thin conducting layer while the other side is left uncoated.
  • the coated side is struck by image-modulated high velocity photoelectrons while the other side is scanned by an electron beam which has practically zero velocity at the target in the absence of charges produced thereon by the signal-modulated photoelectrons but which has a positive velocity dependent on the degree of charge at those elemental areas of the target which are affected by the photoelectrons.
  • An electron multiplier receives and multiplies the electrons given off by the target durin the scanning to produce the output signal;
  • Fig. 1 is a schematic representation of a cathode ray tube of this invention and certain of its associated circuits and auxiliary apparatus;
  • Fig. 2 is a schematic view showing, in greatly enlarged form, a portion of the target and of the photoelectric cathode associated therewith.
  • Fig. 1 shows, by way of example to illustrate the invention, a cathode ray television transmitter tube generally of the image orthicon type described in the Rose, Weimer and Law article mentioned above but employing, instead of the thin glass target and its accompanying fine mesh screen, a two-sided mosaic target ll containing material exhibiting the property of electron bombardment induced conductivity.
  • the target H comprises a layer or sheet E2 of material exhibiting the property of electron bombardment in prised conductivity coated on one side with a very thin conducting coating I3 of, for example, gold or platinum.
  • the layer i2 is a very thin out of diamond or a simulated sheet of diamond formed by a crystalline layer (preferably one particle thick) of diamond chips or diamond dust.
  • any other suitable material exhibiting the property of bombardment induced conductivity can be used instead of diamond.
  • the layer 12 can be of the order of a millimeter thick, for example.
  • a metallic barrier l 4 Surrounding the target is a metallic barrier l 4 which prevents photoelectrons from passing around the target into the space at the right of the target in Fig. l.
  • the elements is and I4 can be placed at the same potential, if desired.
  • the tube l0 comprises an evacuated container enclosing the mosaic target I l an electron-optical system l5 for producing an electron beam and including a cathode 56, a control electrode M, an accelerating electrode l8 having a relatively large aligning disc i9 with an aperture 20 therein, a cylinder 2], a metallic anode member 22 which is preferably a coating on the inside walls of the tube, and a metallic alignment ring 23.
  • the tube H) is also provided with an electron multiplier 24 of any suitable type but which is preferably of the pin-wheel type used in the commercial image orthicon.
  • a photosensitive surface 25, preferably on the inside wall at the end of the tube it] serves as a photocathode.
  • External to the tube it are a deflection yoke or coils 26, a focussing coil 2'! and an alignment coil 28 similar to corresponding members in the image orthicon and the purpose of which will be described more fully below.
  • the cathode I6 is heated by any suitable heater 29 receiving current from a source 36.
  • the cathode i6 is placed at a potential of, for example, 3G0 volts (but which may, for example, be appreciably higher) with respect to ground by means of a source 3i whose positive terminal is grounded and whose negative terminal is connected to member 56.
  • the adjustable source 32 holds the control electrode ii at a suitable negative potential with respect to the cathode l8.
  • Electrode i8, with its apertured disc i9, is connected to ground.
  • Electrode 2! is held at roughly 200 volts positive with respect to the cathode by means of adjustable source 33, whose negative terminal is connected to the negative terminal of source 31.
  • the coating 22 is connected to the cathode through an adjustable source 3 of such value that it is roughly 250 volts positive with respect to the cathode.
  • the metal ring 23 is placed at a suitable positive potential with respect to the cathode by means of an adjustable source 55.
  • the metal coating l3 on the target II is placed at the potential of ground while the photoelectric cathode 25 is placed at a potential of about 10,000 volts below ground by means of a suitable source 3 5.
  • the highest potential of the electron multiplier 24 is about 1500 volts positive with respect to ground and this potential is applied by means of source 3?, the negative terminal of which is connected to ground and to the alignment disc l9 which actually is the first electrode of the multiplier.
  • Various intermediate potentials for the intermediate electrodes of the electron multiplier 2 are provided by means of taps 38, 39, 40 and 4!, respectively, of a potentiometer resistor 42 connected across the source 37.
  • the positive terminal of the source 31 is connected to the final anode or collector of the multiplier 24 through an output resistor 43.
  • an output amplifier 44 Connected across the resistor 43 is an output amplifier 44, the coupling circuit of which includes a coupling condenser 45.
  • the amplifier 44 is in turn connected to the other elements of the television transmitter circuit which prepare a video current for transmission to the receiving station.
  • Fig. 2 is an enlarged view of a portion of the mosaic target ll and the photocathode 25. Certain dimensions in Fig. 2 have been exaggerated at the expense of others in order to more clearly show the screen structure. It is to be understood that relative dimensions shown in Fig. 2 are not necessarily those which exist in a tube constructed in accordance with the invention. Radiations from an object or field of view 0 are projected upon the left-hand side of the tube ill and strike photocathode 25, these radiations being focussed by any suitable lens system represented schematically by th single lens 46.
  • Photoelectrons are emitted from the photocathode 25 in direct proportion to the brightnesses of the various parts of the object or field of view to be televised.
  • the photoelectrons released from the member 25 are accelerated from this member towards the mosaic target H by a uniform electric field produced by the source leaving the photocatho'de 25' is substantially imaged on the coating l3.
  • the magnetic field parallel to the axis of the tube, produced by focussing coil 21" also exerts some fo'cussing action.
  • the paths .of the photoelectrons between the members'25 and I 3 are substantially straight lines parallel to the axis 50' that the electron image has unityrnagnification'.
  • the positive charge current can be many times the photoelectric current from the member 25.
  • the positive charge incremeht on a given elementary region of the uncoated face of the layer I2 accumulates for a" irame time under the influence of the radiations from the object 0.
  • a beam of electrons scans the uncoated side of this layer.
  • the scanning beam is of the low velocity type used in the commercial image orthicon tube.
  • the beam starts at the thermionic cathode l6 at a potential of about -300 volts (with respect to ground) and is accelerated by the electron-optical system I5 to approximately zero volts (actually 300 volts positive with respect to the cathode). From the cathode It to the target H the beam is acted upon by the approximately uniform magnetic focussing field produced by the coil structure 21 and the transverse magnetic field produced by the deflection coils 26.
  • the beam electrons approach the target they are decelerated again to approximately cathode potential, that is 300 volts. If there is no positive charge increment on the layer l2, all the electrons are reflected and return toward the cathode I6 along their initial paths as indicated in Fig. 1. If there is a positive charge pattern on the layer l2, the electrons from the beam are deposited in sufficient numbers to neutralize the positive charge increment thereon and restore the potential of the region to that of the cathode, that is, about '-300 volts.
  • the remaining electrons are reweaves flected. back toward the cathode as indicated in the drawing.
  • all the beam current is returned to the electron multiplier 24 concentricv with the cathode [6.
  • the number of electrons in the return beam is reduced by the amount required to neutralize the positive charge increments on the layer l 2.
  • This reduction in intensity of the return beam to the electron multiplier 24 constitutes the video signal information.
  • the return beam arrives. in the region of the cathode I 6 very near the defining aperture 20 through which it emerged but considerably enlarged in cross-section. This return beam strikes the disc 19' at a sufhcient velocity to generate a larger number of secondary electrons than there are primary electronsv in the returning beam.
  • This disc l9 serves as the first stage of the electron multiplier Z4, the sec ondary electrons from” it being focussed into the succeeding stages of the multiplier 24 which are arranged concentric with and behind this first stage, the whole multiplier being represented in the drawing bythe structure 24.
  • the number of stages of the electron multiplier need not be large; for example, five stages (or less) oi electron multiplication is sufficient.
  • the type of multiplier used in the image orthicon tube is satisfactory for this purpose.
  • the output current from the final stage of the multiplier 24 is taken-from the resistor 43 and applied through the coupling condenser 45 to the wide band television amplifier 44 where it is amplified and applied, as above described, to other elements of the television transmitter circuit.
  • the alignment coil 28 is used, as in the image orthicon, to correct for helical motion resulting from misalignment of the electron gun and the magnetic field produced by the focussing coil 21.
  • the position of the ring 23 and the potential thereof are chosen to correct for helical motion resulting from the deflection fields produced by the yoke 26, also as in the wellknown image orthicon type of tube.
  • One advantage of the tube of this invention is its freedom from stray secondary electron emission trouble. Another important advantage is the very considerable internal charge multiplication in the crystal. Also it is possible to build up a potential variation over the crystal face of many volts as compared with the approximately one-volt limitation of the commercial model of the image orthicon tube. This makes it possible to obtain much higher signalto-noise ratios, and cases the requirement of making the approach energy of the beam constant over the target area.
  • An electron camera tube comprising a target for electrons including a thin, substantially continuous layer of an electrical insulator which has the property of becoming an electronic conductor when bombarded with a beam of low velocity electrons, a conducting coating on one side of said layer, means for forming and directing to said coating image-modulated, high velocity photoelectrons, and means for scanning the side of said target remote from said conducting coating with said beam of electrons.
  • An electron camera tube comprising means for generating a beam of low velocity electrons, a target for said electrons including a thin, substantially continuous, layer of an electrical insulator which has the property of becoming an electronic conductor when bombarded with electrons, a conducting coating on the side of said layer remote from said beam, means for forming and directing to said coating image-modulated high velocity electrons, and means for causing a low velocity beam to scan the side of said target remote from said conductin coating.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US5009A 1948-01-29 1948-01-29 Electron camera tube Expired - Lifetime US2544753A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL79223D NL79223C (sv) 1948-01-29
BE486171D BE486171A (sv) 1948-01-29
US5009A US2544753A (en) 1948-01-29 1948-01-29 Electron camera tube
FR975726D FR975726A (fr) 1948-01-29 1948-12-01 Tube-caméra électronique
GB2411/49A GB711202A (en) 1948-01-29 1949-01-28 Electron camera tubes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US5009A US2544753A (en) 1948-01-29 1948-01-29 Electron camera tube

Publications (1)

Publication Number Publication Date
US2544753A true US2544753A (en) 1951-03-13

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US5009A Expired - Lifetime US2544753A (en) 1948-01-29 1948-01-29 Electron camera tube

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US (1) US2544753A (sv)
BE (1) BE486171A (sv)
FR (1) FR975726A (sv)
GB (1) GB711202A (sv)
NL (1) NL79223C (sv)

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2588292A (en) * 1950-04-20 1952-03-04 Philips Lab Inc Electron switching tubes and circuits therefor
US2598401A (en) * 1948-02-18 1952-05-27 Emi Ltd Electron discharge device suitable for use as television transmitting tubes
US2683832A (en) * 1948-04-15 1954-07-13 Pye Ltd Image pickup electron tube
US2710813A (en) * 1951-01-02 1955-06-14 Rca Corp Cadmium selenide-zinc selenide photoconductive electrode and method of producing same
US2733364A (en) * 1956-01-31 flory
US2734145A (en) * 1949-10-27 1956-02-07 William
US2747133A (en) * 1950-07-05 1956-05-22 Rca Corp Television pickup tube
US2747131A (en) * 1951-10-12 1956-05-22 Sheldon Edward Emanuel Electronic system sensitive to invisible images
US2747132A (en) * 1951-12-18 1956-05-22 Sheldon Edward Emanuel Device sensitive to invisible images
US2749463A (en) * 1951-10-24 1956-06-05 Bell Telephone Labor Inc Solid state television pick-up tube
US2776387A (en) * 1951-07-30 1957-01-01 Rca Corp Pick-up tube with induced conductivity target
US2777970A (en) * 1950-10-03 1957-01-15 Paul K Weimer Television camera storage tube
US2840755A (en) * 1952-03-21 1958-06-24 Westinghouse Electric Corp Large storage low noise image tube
US2849635A (en) * 1952-12-09 1958-08-26 Philips Corp Television pick-up tube
US2851625A (en) * 1952-10-30 1958-09-09 Rca Corp Image tube
US2851624A (en) * 1951-10-12 1958-09-09 Sheldon Edward Emanuel Tube sensitive to images of invisible radiation
US2863087A (en) * 1952-05-27 1958-12-02 Csf Photo-conductive electron discharge tube
US2864031A (en) * 1950-12-30 1958-12-09 Rca Corp Electrical storage tube
US2911562A (en) * 1957-09-20 1959-11-03 Thompson Ramo Wooldridge Inc Television camera circuits
US2922907A (en) * 1958-05-23 1960-01-26 Gen Electric Target electrode assembly
US2928969A (en) * 1956-05-11 1960-03-15 Westinghouse Electric Corp Image device
US2951962A (en) * 1959-05-22 1960-09-06 Rca Corp Pickup tube assembly
DE974081C (de) * 1951-03-20 1960-09-08 Hans-Werner Dr Rer Nat Paehr Anordnung fuer Bildaufnahmeroehren
DE1120035B (de) * 1958-02-18 1961-12-21 Optische Ind Iade Oude Delftia Elektronen-optische Abbildungsvorrichtung
US3148297A (en) * 1959-11-27 1964-09-08 Westinghouse Electric Corp Electron device with storage capabilities
US3213316A (en) * 1962-12-03 1965-10-19 Westinghouse Electric Corp Tube with highly porous target

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL243461A (sv) * 1959-09-17

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2251992A (en) * 1938-06-15 1941-08-12 Rca Corp Picture transmitter tube
US2401786A (en) * 1942-10-23 1946-06-11 Rca Corp Television transmitting apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2251992A (en) * 1938-06-15 1941-08-12 Rca Corp Picture transmitter tube
US2401786A (en) * 1942-10-23 1946-06-11 Rca Corp Television transmitting apparatus

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2733364A (en) * 1956-01-31 flory
US2598401A (en) * 1948-02-18 1952-05-27 Emi Ltd Electron discharge device suitable for use as television transmitting tubes
US2683832A (en) * 1948-04-15 1954-07-13 Pye Ltd Image pickup electron tube
US2734145A (en) * 1949-10-27 1956-02-07 William
US2588292A (en) * 1950-04-20 1952-03-04 Philips Lab Inc Electron switching tubes and circuits therefor
US2747133A (en) * 1950-07-05 1956-05-22 Rca Corp Television pickup tube
US2777970A (en) * 1950-10-03 1957-01-15 Paul K Weimer Television camera storage tube
US2864031A (en) * 1950-12-30 1958-12-09 Rca Corp Electrical storage tube
US2710813A (en) * 1951-01-02 1955-06-14 Rca Corp Cadmium selenide-zinc selenide photoconductive electrode and method of producing same
DE974081C (de) * 1951-03-20 1960-09-08 Hans-Werner Dr Rer Nat Paehr Anordnung fuer Bildaufnahmeroehren
US2776387A (en) * 1951-07-30 1957-01-01 Rca Corp Pick-up tube with induced conductivity target
US2747131A (en) * 1951-10-12 1956-05-22 Sheldon Edward Emanuel Electronic system sensitive to invisible images
US2851624A (en) * 1951-10-12 1958-09-09 Sheldon Edward Emanuel Tube sensitive to images of invisible radiation
US2749463A (en) * 1951-10-24 1956-06-05 Bell Telephone Labor Inc Solid state television pick-up tube
US2747132A (en) * 1951-12-18 1956-05-22 Sheldon Edward Emanuel Device sensitive to invisible images
US2840755A (en) * 1952-03-21 1958-06-24 Westinghouse Electric Corp Large storage low noise image tube
US2863087A (en) * 1952-05-27 1958-12-02 Csf Photo-conductive electron discharge tube
US2851625A (en) * 1952-10-30 1958-09-09 Rca Corp Image tube
US2849635A (en) * 1952-12-09 1958-08-26 Philips Corp Television pick-up tube
US2928969A (en) * 1956-05-11 1960-03-15 Westinghouse Electric Corp Image device
US2911562A (en) * 1957-09-20 1959-11-03 Thompson Ramo Wooldridge Inc Television camera circuits
DE1120035B (de) * 1958-02-18 1961-12-21 Optische Ind Iade Oude Delftia Elektronen-optische Abbildungsvorrichtung
US2922907A (en) * 1958-05-23 1960-01-26 Gen Electric Target electrode assembly
US2951962A (en) * 1959-05-22 1960-09-06 Rca Corp Pickup tube assembly
US3148297A (en) * 1959-11-27 1964-09-08 Westinghouse Electric Corp Electron device with storage capabilities
US3213316A (en) * 1962-12-03 1965-10-19 Westinghouse Electric Corp Tube with highly porous target

Also Published As

Publication number Publication date
NL79223C (sv)
FR975726A (fr) 1951-03-08
BE486171A (sv)
GB711202A (en) 1954-06-30

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