US2146822A - Television - Google Patents

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Publication number
US2146822A
US2146822A US647440A US64744032A US2146822A US 2146822 A US2146822 A US 2146822A US 647440 A US647440 A US 647440A US 64744032 A US64744032 A US 64744032A US 2146822 A US2146822 A US 2146822A
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United States
Prior art keywords
plate
elements
cell
anode
light
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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
US647440A
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English (en)
Inventor
Henroteau Francois Char Pierre
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.)
RCA Corp
Original Assignee
RCA 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
Priority to NL43516D priority Critical patent/NL43516C/xx
Priority to BE400336D priority patent/BE400336A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US647440A priority patent/US2146822A/en
Priority to GB35104/33A priority patent/GB413954A/en
Priority to FR765508D priority patent/FR765508A/fr
Application granted granted Critical
Publication of US2146822A publication Critical patent/US2146822A/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
    • 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
    • H01J31/40—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having grid-like image screen through which the electron ray passes and by which the ray is influenced before striking the output electrode, i.e. having "triode action"
    • 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

Definitions

  • Yet anotherobject of the invention is to pro- ⁇ vide a, method whereby each point of the scene,
  • a further object of. the invention is toprovide a method whereby all the points of the scene to be televised are simultaneously projected on the transmitter and not successively projected thereon, as is the case with all practical' methods' of television now in use.
  • eachelement l will be projected on the transmitting screen for only one one hundred and sixty-thousandth vof a second. It is known that the electric energy liberatedby ⁇ 5 photoelectric material is proportional to the amount. of light falling on the materialmultiplied by the' time during which the light acts.
  • transmission is 'divided into three or, in one casa-'fourperiods, the scene being projected on the transmitter during one of these periods. Sinceall theelements of e Y the scene are simultaneously projected on the' transmitter, the light from eachelement Aof the former falls on the'latter fLone-third *ofl vone sixteenth of a second, that is,1for'almost four v'thousand times longer than in known methods. lf, however, the.
  • a furtherv object of the invention is, ⁇ t herefore, in a method where .all vpoints Jfthevscene are siy multaneously projected-oriv the :'transmitter, yto ensure that as large a proportion as possible ofthe energy of the scanning beam becomes effec- 40 tive for transmission.
  • a still further object ofthe invention is,. ina method as referred to in the last paragraph, to obtain an eiective energy f or transmission ⁇ as nearly as possible equal to" thefenergy liberated under the influence Vof the light from the view.
  • the cathode was uniformly photosensitive and the electrostatic reproduction of the image of the view was formed by collecting on a grid consisting of a multiplicity of mutually insulated electro-conductive elements non-photosensitive to visible but photosensitive to ultra-violet light, the electronic emission from the cathode resulting from the projection thereof of the image of the view.
  • the grid was interposed between the anode and cathode and, during subsequent scanning of the cathode by a strong beam of light to cause the emission from it of an electronic stream, the electrostatic reproduction of the view formed on the grid modulated this stream, thus causing the current received by the anode to be modulated in accordance with the light from the view. .To cause the electrostatic reproduction to disappear, the grid was exposed to ultra-violet light which caused the elements to emit electrons until they reached a uniform and slightly positive potential.
  • Mry present method and apparatus differ essentially from those described above in a number of respects.
  • I provide a cell having at one side thereof an opening through which the image of a view maybe focussed and at the opposite side thereof an opening through which a beam of light for causing the electrostatic reproduction of the view to disappear may be projected.
  • Arranged in the cell between these openings are an anode and two members or plates each formed with a multiplicity of tiny openings therethrough and arranged parallel, close to and in such relation to one another that the openings of one plate are opposite the solid portions of the other.
  • These plates are interposed between the anode and the opening for the image of the view. That nearest this opening will be referred to as the first plate and that nearest the anode as the second plate.
  • the rst plate has an insulating coating on it and its surface facing the anode carries, opposite the openings in the second plate, a multiplicity of mutually insulated electroconductive elements having photosensitive surfaces.
  • the surface of the second plate facing the opening for the light from the view is made photosensitive.
  • Formed as a part of the cell in the side thereof out of line with the openings therein is a cathode ray oscillograph, the beam of rays from which is not designed to strike a fluorescent screen, but is designed to scan the surface of the second plate facing the anode at such an angle that it will not pass through the openings in this plate.
  • the first plate is at a low positive potential
  • the second plate and the anode are grounded and no emission of cathode rays is taking place.
  • the 1( the light from different parts of the view, differ- 1g ent areas of this photosensitive surface will emit different numbers of electrons which will be picked up by the nearest electro-conductive elements on the first plate, owing to the slight positive potential to which this plate is raised. In 21 this way the elements will be raised to varying negative potentials, and as a whole 'they will thus carry an electrostatic reproduction of the View.
  • the first plate is raised to a very low positive po- 2i tential
  • the second plate is grounded
  • the anode is raised to a comparatively high positive potential.
  • a beam of cathode rays from the cathode ray oscillograph scans the surface of the second plate facing the anode and causes a sec- 3
  • Figure 1 is a diagrammatic view of the complete transmitting arrangement.
  • Figure 2 is a front view of one of the plates showing in dotted lines the positions of the openings in the other plate when the two plates are properly mounted.
  • Figure 3 is a cross-sectional view through my preferred system of plates, showing their arrangement with reference to one another and the various coverings and layers on them, the thickness of these coverings and layers being very greatly exaggerated.
  • Figure 4 is a similar view of a modified system of plates.
  • Figure 5 is an elevation of one of the discs used for permitting entry of light to the cell at proper intervals.
  • I is a cell darkened to prevent the entry of light thereinto except through openings 2 and 3, the cell being suitably of cylindrical form and the openings being at each end of the cylinder.
  • a pocket-like portion 4 arranged in the form of a cathode ray oscillograph, the place of the fluorescent screen of which is taken by an opening into the cell.
  • 'I'he oscillograph is provided with the usual anode 5, having a very small opening therein, an electron emitting cathode 6 and pairs of magnets I and 8, for oscillating the beam of cathode rays.
  • the cell and the portion 4 are electrically shielded by a shielding 9 which is grounded at I0.
  • this shielding is made in the form of a relatively wide mesh screen so that it will interfere as little as possible with thepassage of light.
  • a metallic screen Il Connected and arranged parallel to and inside the shielding 9 at some distance therefrom is a metallic screen Il of relatively narrow mesh but made up of very thin wires. This screen extends over the lower part of the wall of the pocket 4 nearest the opening 3 in the cell and all around that part of the cell between the opening of the pocket 4 and the end in which the opening 3 is situated.
  • a grid I2 of wider mesh than the screen. The grid is insulated from the screen and the shielding and is connected to a battery I3 of relatively high-positive potential.
  • the screen II and shielding 9 constitute a Faraday cage outside which the potential of the grid I2 has no eiect.
  • a lens I4 Outside the cell and in front of the opening 2 is a lens I4 and mounted between it and the opening 2 is a rotatable disc I 5 having therein an opening I6 through which the light from the view may pass at suitable intervals.
  • a lamp I1 At the other end of the cell in front of the opening 3 is a lamp I1 having before it a screen I8 designed to let pass only light of such wave length as will detach from a photosensitive surface electrons of relatively very low velocity.
  • a rotatable disc I9 Similar to the disc I5 but having in it an opening extending over a lesser arc.
  • the three commutators 24, 25 and 25 and the rotatable discs I5 and I 9 are preferably mounted for rotation upon a common shaft 23a. YArranged around each commutator are three contacts spaced from each other by 120 of arc.
  • and 32 are connected to the positive terminal of a battery 33 of low voltage, the positive terminal of a battery 34 of even lower voltage and ground 35 respectively.
  • the contacts 35 and 38 are connected to grounds 39 and respectively, while the contact 31 is connected to the grid 4I of a thermionic tube 42 and also through a resistance 43 to the positive terminal of a battery 44 of relatively high voltage.
  • the contacts 45, 46 and 41 are connected to ground 48, the negative terminal of a battery 49 of high voltageand ground 50 respectively.
  • FIGs 2 and 3 the construction and arrangement of the plates 20 and 2
  • the plate 20 is composite and is made up of sections 5I, 52 and 53, all perforated correspondingly.
  • the section 52 is offset with respect to the sections 5I and 53 in a direction towards the opening of the cathode ray oscillograph portion 4 so that in this direction the openings 54 through the plate are about half as long as in the direction perpendicular to it.
  • the angle of incidence of the beam 55 of cathode rays on the surface of the plate 20 is so chosen that this beam will always strike the surface 55 of the section 52 and never the side walls 5'I of its openings. It is of course desirable that the angle of incidence of the beam of cathodel rays be as small as possible in order that at any one time the beam may cover as small an area of the plate as possible. For this reason, while the sections 5I and 52 should be made as thin as possible the section 53 may be made thicker than these sections so that the angle of incidence of the beam of cathode rays may be reduced without, however, the beam being able to penetrate through the openings in the plate.
  • is entirely coated with a layer of aluminium oxide 58, overlying a layer of pure aluminium 59.
  • On the surface of this plate facing the plate 20 and covering areas the full size of the openings 60 in the section 5I of the plate 2l are formed mutually insulated electroconductive elements designated generally by the numeral 6I.
  • These elements 6I have photosensitive surfaces 62 of caesium, intermediate layers 53 of caesium' oxide silver and in-
  • , has a photosensitive coating 65 of caesium and underneath it an intermediate layer 66 of caesium oxide silver and an inside layer 51 of silver.
  • are preferably made of pure copper, for example, electrolytic copper which can be produced in sheets having a. thickness as small as one two-thousandths of an inch. At this thickness the plates may easily be perforated with a number of openings up to ten thousand or more to the square inch by means of photo-engraving, as used in the preparation of ordinary half-tone plates. After being perforated, the plates are placed in a tube heated to red heat and degasied by means of the formation of a high vacuum in the tube.
  • the plate In order to prepare the insulating coating on the plate 2
  • the coated plate is then used as the anode in an electrolytic bath in which the electrolyte is, for example, a concentrated solution of borax and boracic acid.
  • the electrolyte is, for example, a concentrated solution of borax and boracic acid.
  • the potential may be gradually increased to 350 volts and then retained at this point for some time in order to insure absolute uniformity of the coating.
  • After its coating with aluminium oxide, the plate 2
  • a bead of silver is now exploded through the openings in the auxiliary plate ontothe plate 2
  • thereof is placed in a high vacuum tube and silver exploded onto it without, however, any plate being interposed between it and the source of the explosion.
  • the section has, thus, a uniform coating 61 of silver over one surface and probably also incidentally along the walls of the openings 60 through it.
  • a coating of silver oxide is then formed on the silver in the manner described withreference to the plate 2
  • the two plates When the two plates have been thus prepared, they are mounted in the nai tube in the relation to each other described above and shown in the drawings, the silver oxide elements on the plate 2
  • the interior of the cell is now heated to a temperature of about 125 C. and at the same time a pellet 69 of a mixture of caesium dichromate and silicon contained in a side pocket 10 of the cell I is heated and caesium vapour evolved.
  • the tube is during this time under a high vacuum and is kept thereunder by a pump attached at 1
  • the caesiumy vapour reacts with the silver ⁇ oxide with the formation of caesium oxide silver, which is referred to thus since it is not well known whether the caesium oxide and silver are in distinct layers or not.
  • On the outside of this layer of caesium oxide silver is formed a layer of pure caesium which, though only one atom thick, is extremely tenacious.
  • the surplus caesium is partly removed by the pump and, after the reaction with the silver oxide is complete, the tube is heated to a temperature of 250 C., at which temperature the remaining caesium vapour is fixed by a getter such, for example, as lead glass.
  • the cell is then sealed oif at 1
  • FIG 4 I have shown a system of plates somewhat different from that of my preferred system.
  • 'I'his system includes, as in my preferred system, the plates 20 and 2
  • an unperforated transparent plate 12 of insulating material such as. for example, mica, is interposed between the plates 20 and 2
  • are formed opposite solid portions of the plate 2
  • the insulating plate 12 may be made as thin as possible, and is arranged at the same distance from the plate 2
  • the plate 20 is arranged in exactly the same way as in my preferred system.
  • transmission is carried out in four operations, while with the system of plates shown in Figure 4 transmission is in three operations, all of which take place Within one-sixteenth of a second.
  • the division of the total time between the various audace operations will depend upon circumstances, but in general, with either system of plates the rst two operations will each last l5@ second, while with the preferred system the last two operations will each last l/m second, and with the modified system the third'operation will last .360 second.
  • the length of time for the iirst operation might, for example, be increased to iH00 second, and that for the second' operationl reduced to M00 second. It may also be found desirable, when using the preferred system of plates, to lengthen the time for the third operation at the expense of that for the fourth operation.
  • the cathode ray oscillograph portion 4 is caused to emit a beam 55 of cathode rays, which is caused by the magnets 'I and 8 to scan the surface of the plate 20 facing the anode. the beam striking this surface at approximately the angle shown in Figures 3 and 4. Under the influence of the beam a secondary electronic emission is produced from every part of the plate 20 which is struck. As is known, the greater part of the secondary emission is made up of relatively slow moving electrons which, on being emitted, are subjected to two attractions acting in opposite directions.
  • the first of these is that of the anode 22 and the second is that of the positive potential of the plate 2
  • That part which consists of slow moving electrons will be divided in accordance with the relative intensities of the two attractions to which it is subjected.
  • the electronic current reaching the anode from any area of the surface of the plate 20 will therefore depend upon the negative potential of the element 6
  • the electronic current reaching the anode during the scanning operation will be one modulated by the electrostatic reproduction of the image of the view.
  • the variations of potential caused in the anode by the reception of the modulated electronic. current are impressed on the grid 4
  • are at various negative potentials the rest of the members of the cell are positive with respect to them and will thus attract any electrons which they emit under the iniuence of the light striking them.
  • has, as is Well known, the property of opposing a resistance approximately a thousand times as great to the passage of current from a negative element to a positive element as from a positive element to a negative element. Thus while the elements 6
  • the elements are thus all brought to a uniform and slightly positive potential, which potential will not be exceeded owing to the increased leakage of current above it from the elements to the plate, and also owing to the fact that above it electrons emitted will be re-attracted by reason of the higher positive potential.
  • the frequency band necessary for transmission might be narrowed if, instead of using only one apparatus where the whole cycle of operations is completed in one sixteenth of a second. three apparatuses were used. In this case while the ilrst apparatus was performing operation (a) the second would be performing operation (h) and the third operations (c) and (d). Thus. though a picture would be transmitted every 116 second each operation could last 1*.,- instead of only 1,?,0 of a second. This would be of importance in transmitting the picture since transmission could then be spread over three times the period which could be allowed when only one apparatus was used and the frequency band for transmission thus narrowed.
  • Very strong, enlarged and contrasted images of very faint, still objects could be produced with my system owing to electrical amplification.
  • the disc I would be brought to a position to allow the view to fall on plate 20 for a suitable length of time.
  • the shaft 29a would then be rotated to a position to allow scanning of the screen and this scanning could be repeated without any intermediate operation for as long as desired since the electrostatic image of the object would always remain on the elements 6
  • My device could, for instance, be attached to a powerful astronomical telescope and, while the image focussed would be large and weak, a very vivid strong image would appear on the receiver.
  • the device could also be attached to a microscope and permit hitherto invisible objects to be seen.
  • Apparatus for the electrical transmission or images which comprises means for impressing an image upon a photosensitive surface, means for scanning a surface other than said photosensitive surface to cause the emission of an electronic stream of substantially constant intensity from said other surface, means for causing the formation at one time of an electrostatic reproduction of the whole of said image to modulate said stream, an anode for picking up the modulated stream, and means for thereafter causing said electrostatic reproduction to disappear.
  • Apparatus for the electrical transmission of images which comprises means for impressing an image upon a photosensitive surface, means for scanning a surface other than said photosensitive surface to cause the emission of an electronic stream of substantially constant intensity from said other surface, means for causing the formation at one time of an electrostatic reproduction of the whole of said image to modulate said stream, an anode for picking up the modulated stream and means for thereafter exposing said electrostatic reproduction to infra red light.
  • Apparatus for the electrical transmission of images which comprises means for impressing an image upon a photosensitive surface, means for scanning a surface other than said photosensitive surface to cause the emission of an electronic stream of substantially constant intensity from said other surface, means for causing the formation at one time of an electrostatic reproduction of the whole of said image to modulate said stream, an anode for picking up the modulated stream, means for thereafter exposingl said electrostatic reproduction to infra red light, and means for stopping said exposure a substantial time before an image is again impressed upon the photosensitive surface.
  • Apparatus for the electrical transmission of images comprising a cell, a photosensitive surface within said cell, means for impressing an image on said surface, means in the form of a multiplicity of mutually insulated elements for retaining an electrostatic reproduction of said image, said elements being formed on the surface facing said photosensitive surface of a member interposed between said photosensitive surface and the view.
  • Apparatus for the electrical transmission of images comprising a cell, a photo-sensitive surface within said cell, means for impressing an image on said surface, means in the form of a multiplicity of mutually insulated elements for retaining an electrostatic reproduction of said image, said elements being formed in the surface facing said photosensitive surface of an opaque member interposed between said photosensitive 5 surface and the object of which an image is projected on said photosensitive surface and formed with a multiplicity of openings therethrough.
  • Apparatus for the electrical transmission of images comprising a cell, an opening in said cell 1 for the projection therethrough of an image, an anode in said cell, a member between said anode and said opening having amultiplicity of openings therethrough and having a pluotosensitive surface facing said opening, another member be- 1 tween said opening and said first mentioned member and having on its surface directed towards said lfirst mentioned member a multiplicity of mutually insulated elements arranged opposite the openings in said first mentioned member, 2 means for impressing an image on said photosensitive surface, means for causing'said multiplicity of elements to retain an electrostatic reproduction of said image and means for scanning the surface of said rst mentioned member fac- 2 ing said anode to cause an electronic emission from said surface and means for picking up said emission, modulated by the electrostaticl reproduction, at the anode.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)
US647440A 1932-12-15 1932-12-15 Television Expired - Lifetime US2146822A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL43516D NL43516C (bg) 1932-12-15
BE400336D BE400336A (bg) 1932-12-15
US647440A US2146822A (en) 1932-12-15 1932-12-15 Television
GB35104/33A GB413954A (en) 1932-12-15 1933-12-13 Improvements in television
FR765508D FR765508A (fr) 1932-12-15 1933-12-14 Perfectionnements aux procédés et appareils de télévision

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US647440A US2146822A (en) 1932-12-15 1932-12-15 Television

Publications (1)

Publication Number Publication Date
US2146822A true US2146822A (en) 1939-02-14

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Application Number Title Priority Date Filing Date
US647440A Expired - Lifetime US2146822A (en) 1932-12-15 1932-12-15 Television

Country Status (5)

Country Link
US (1) US2146822A (bg)
BE (1) BE400336A (bg)
FR (1) FR765508A (bg)
GB (1) GB413954A (bg)
NL (1) NL43516C (bg)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2651674A (en) * 1949-02-18 1953-09-08 Cathodeon Ltd Television transmission from intermittent film by means of pulsed pickup tube
US2655554A (en) * 1948-06-03 1953-10-13 Emi Ltd Generation of picture signals for television transmission
US2696523A (en) * 1949-10-27 1954-12-07 Pye Ltd Television apparatus with divided frame interval
US2756364A (en) * 1951-01-05 1956-07-24 Pye Ltd Television transmitting apparatus
US2839699A (en) * 1948-02-19 1958-06-17 Rauland Corp Image converter tube
US2850565A (en) * 1952-01-24 1958-09-02 Farnsworth Res Corp Television camera tube arrangement with fading control utilizing an additional camera tube
US2883657A (en) * 1946-05-08 1959-04-21 Alfred G Emslie Moving target radar system
US20070026771A1 (en) * 2005-07-27 2007-02-01 Kathleen Harden Edge buster series round blade sharpener and the edge tracker sharpener

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2883657A (en) * 1946-05-08 1959-04-21 Alfred G Emslie Moving target radar system
US2839699A (en) * 1948-02-19 1958-06-17 Rauland Corp Image converter tube
US2655554A (en) * 1948-06-03 1953-10-13 Emi Ltd Generation of picture signals for television transmission
US2651674A (en) * 1949-02-18 1953-09-08 Cathodeon Ltd Television transmission from intermittent film by means of pulsed pickup tube
US2696523A (en) * 1949-10-27 1954-12-07 Pye Ltd Television apparatus with divided frame interval
US2756364A (en) * 1951-01-05 1956-07-24 Pye Ltd Television transmitting apparatus
US2850565A (en) * 1952-01-24 1958-09-02 Farnsworth Res Corp Television camera tube arrangement with fading control utilizing an additional camera tube
US20070026771A1 (en) * 2005-07-27 2007-02-01 Kathleen Harden Edge buster series round blade sharpener and the edge tracker sharpener

Also Published As

Publication number Publication date
BE400336A (bg)
NL43516C (bg)
FR765508A (fr) 1934-06-12
GB413954A (en) 1934-07-26

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