US1903113A - Television - Google Patents

Television Download PDF

Info

Publication number
US1903113A
US1903113A US480480A US48048030A US1903113A US 1903113 A US1903113 A US 1903113A US 480480 A US480480 A US 480480A US 48048030 A US48048030 A US 48048030A US 1903113 A US1903113 A US 1903113A
Authority
US
United States
Prior art keywords
light
cathode
photoelectric
anode
grid
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
US480480A
Other languages
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.)
Individual
Original Assignee
Individual
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 US20187D priority Critical patent/USRE20187E/en
Priority to BE363913D priority patent/BE363913A/xx
Priority claimed from US367084A external-priority patent/US1903112A/en
Priority claimed from GB2483530A external-priority patent/GB335995A/en
Application filed by Individual filed Critical Individual
Priority to US480480A priority patent/US1903113A/en
Application granted granted Critical
Publication of US1903113A publication Critical patent/US1903113A/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
    • H01J31/265—Image pick-up tubes having an input of visible light and electric output with light spot scanning

Definitions

  • Another object of the invention is to permit the transmission of animate or still vlews under ordinary daylight illumination regardless, within limits, of the size o f these views, that is to transmit all views which 1t 1s possible at present to photograph with a moving picture camera.
  • a further object of the invention is to provide a method whereby each point of the scene to be televised can be impressed on the photoelectric surface for a far greater time than has hitherto been possible.
  • a still further object of the invention is to provide a method whereby all the points of the sceneto be televised are simultaneously S5 projected on the transmitter and not successively projected thereon, as is the case with all practical methods of television now'in use.
  • C3 method differs radically from the above method in that all the elements of the' scene are simultaneously projected on the transmitter. If, according to known methods, it is desired to transmit an entire s-cene i3 every sixteenth of a second and the scene is to be divided into ten thousand elements, then each element will be projected onv the transmitting screen for only one one-hundred and sixty thousandth of a second. a
  • the light of the scanningfbeam can be made, on the average, ten thousand times greater than the light received from the scene.A Therefore, the electric energy liberated from one element of the photoelectric material of the transmitter will be of the same order of magnitude as the energy liberated by the light of the scene which strikes that element.
  • the energyavailable for the transmission of the scene by my method will b e, on the average, a number of thousand times greater than the energy available for the transmission of the scene by allknown methods.
  • the transmitted v consists of a very great number of small elesurface of the cathode.
  • An anode is provided in the cell and a grid interposed between the anode and the cathode.
  • a transparent window is formed in the cell through which both the view and the scanning beam are projected onto the surface ofthe cathode. Transmission is divided into three stages and is carried out as follows:
  • a strong, comparatively wide beam of light of a certain wave length is projected parallel to the cathode and strikes the coat- 1n of photoelectric material with which the ce is provided on its interior. This light is of such a wave length that the electrons which it detachcs from the photoelectric material will have a velocity of expulsion of almost zero.
  • the grid and anode are grounded so that the electrons emitted by the beam of light will be directed to any of the elements or groups of elements of the cathode which have a positive poten-y tial.
  • all the groups of elements of the cathode will be at practically a uniform potential.
  • the grid and anode are connected to a source of positive potential and the view is projected onto the surface of the cathode. According to the intensity of the light striking each element or set of elements, these will emit more or less electrons and will become more or less positive. The electrons emitted by the cathode will be absorbed by the grid or the anode.
  • the grid is connected to a source of comparatively low negative potential and the anode to a source o positive potential and to the grid of the first three-electrode tube of a transmitter.
  • a scanning beam of very strong light is then caused to pass over the Under the iniuence of this beam the anode will receive more or less electrons from the elements or groups of elements according as these are less or more positive.
  • This modulations will be impressed on the grid of the first three electrode tube of the transmitter, which modulations will correspond to the degree of positive potential to which the elements or group of elements have been raised.
  • the modulations impressed on the transmitter are proportional tothe intensity of the light of the particular part of the view to which they correspond.
  • Figure 1 is a sectional perspective and diagrammatic view illustratin the apparatus employed and showing certain of the electrical connections.
  • Fi ure 2 is a plan view of a form of disc whic may be used to interrupt either the view of the scene, the scanning or the strong beam of light used to brin thereceiving screen nearly to zero' potentia p Figure '3'is a plan view of the two orthogenal scanning lens discs.
  • v is the frequency of the light striking the photoelectric material
  • Iwo also written wo
  • v is a constant called the electron affinity, varying with the nature of the photoelectric metal; it is the minimum energy necessary to tear 1off an electron from the atom of this meta
  • v is smaller than v0 there is no emission of electrons and when vis vsomewhat, larger there is emission of some electrons with a Very small velocity of eX- pulsion.
  • i 1, 1 indicates a suitable photoelectric cell 1n the form of a vitreous or glass container exhausted to a high degree of vacuum in the manner known in the art; 2 indicates generally the cathode located at the back part of the container.
  • This cathode may comprise a metallic plate 3 grounded through a suitable conductor 3a which passes through the wall of the container and is suitably sealed therein.
  • a layer of some insulating material 4 such as aluminum or magnesium oxide and upon this is placed a layer 5 of potassium or other vphotoelectric material, subdivided into tiny elements insulated one from the other.
  • These insulated elements could be pure potassium globules formed in a layer of insulating potassium hydride.
  • the photoelectric material such as potassium
  • the photoelectric material is evaporated on the aluminum oxide, or other insulating medium and treated so as to form a colloidal deposit of potassium hydride containingminute globules of pure potassium.
  • Such a coating of photoelectric material has been prepared before by V. K. Zworykin (see United States Patent No. 1,691,324, November 13, 1928, page 2, lines 1 to 9).
  • the globules are really insulated one from the other and each of them constitutes so to speak a minute and very active photoelectric cell.
  • the surface 5 might also'be prepared by bombarding with cathode rays a very thin layer of potassium hydride; these rays having passed through a very fine sieve transform elementary areas of the screen into groups of line globules of pure potassium. Also, sodium, caesium or rubidium hydride might be used.
  • the portion of the photoelectric cell 6 opposite the cathode 2 constitutes a window and may be formed with a relatively plane surface through which light maybe projected by the lenses 7 and 8, which lenses Will be suitably mounted in relation to the photoelectric cell with the usual provision for adjusting or focusing.
  • the surface 5 should be arranged to coincide with the focal plane of the lens 7, which lens of course could be moved back and forthin order to focus all pictures or scenes at various distances in front of the apparatus.
  • the grid 9 which is positioned Within the photoelectric cell between the cathode and the anode consists of a line screen formed of thin the commutator. Arranged around the periphery of the latter and spaced 120 from each other are contacts 12, 13 and 14 which are connected respectively to ground, a source of moderate positive potential and a source of moderate negative potential.
  • the anode is in the form of a wire loop arranged in a plane parallel to the cathode element 2 and is connected to a conducting wire 16 which extends outwardly through ⁇ the extension 17 of the cell, and is sealed therein.
  • the commutator 18 is of insulating material and, like the commutator 10, is formed with a metallic sector 18a to which the conductor 16 is connected, the angle at the centre of this metallic sector being a little less than 120.
  • Suitable contacts 19, 20 and 21 are arranged about the commutatorv 18 and spaced 120 apart from each other.
  • the Contact 19 is connected to ground, the Contact 2O to a source of positive potential, while the contact 21 is connected to a like source of positive potentialand also to the grid of the lirst three electrode valve of a transmitter.
  • the interior of a large part of the photoelectric cell 1 is coated with a coating 22 of photoelectric material such as' potassium.
  • the coating is designed to be affected at intervals as hereinafter described by an energizing beam of light 23,- this preferably passing through one side of the cell at a direction substantially parallel to the plane of the catliode so as not to strike the latter.
  • This beam of light is interrupted at intervals and is of such colour that the frequency of the colour is somewhat larger than the frequency wo for which electrons are merely detached from the photoelectric material.
  • the electrons emitted 4 have then a very small velocity of eX- pulsion and if all the objects inside the cell are at zero' potential except certain of the elements of cathode surface 5, then all these electrons will be captured by the former.
  • the drawings illustrate a convenient method of producing this beam of light from a very strong source of light 24. ⁇ such as anl arc lamp or a pointolite lamp of high candle power.
  • This light after passing through lens 25 and prism 26, forms a spectrum in the plane of the screen 27 which has a narrow aperture or slit 28 which allows light of the desired wave length to pass, which light after passing through the lens 29 forms the beam 23 which strikes the interior of the photoelectric cell.
  • a coloured beam such as the use of a coloured screen of Iena glass might be usedv if necessary.
  • a bank of several lamps 24 might be used.
  • a rotating disc 30 is provided, the form of which may be as shown in Fig. 2, the disc being formed with a segmental aperture 31 covering an are of somewhat less than 120. This disc is rotated very rapidly and at each revolution the aperture is designed to permit the beam of light to strike' the surface of the photoelectric cell for approximately 1/50 of a second.
  • the image of the view to be televised is formed on the cathode by any convenient lens system.
  • lens 7 designed to form such an image.
  • means for interrupting the light which forms the image this interruption eing conveniently accomplished by a rotating disc 32 of similar form to the disc 30 and rotating at the same speed.
  • Means are also provided for scanning the surface 5 of the. cathode with extreme rapidity.
  • the means which I provide for the purpose include a lens 8 which allows a spot of light to scan the surface 5. lVhile various known methods of scanning may be used with other parts of the apparatus therein described, the following scanning means will be found to possess special utility.
  • These scanning means include a suitable concentrated source of light 33 such as a bright pointolite or arc lamp having brightness as great as 1,000 candle power.
  • a suitable concentrated source of light 33 such as a bright pointolite or arc lamp having brightness as great as 1,000 candle power.
  • the arrangement described with respect to the reduction of the beam 23 may be used, such a short wave length being of advantage in order to obtain a large velocity of expulsion for the electrons emitted by the surface 5 of the cathode.
  • a lens 34 suitably arranged with respect to the light source 33 and designed to project a beam through a prism 35 from the spectrum of which the light of the desired colour will be selected by a screen 36 having a suitable aperture 37 therein.
  • the light passing through the aperture 37 is interrupted by a rotating disc 38 similar in form to the disc 30 and rotating at the same speed.
  • the three discs 30, 32 and 38 are all rotated at the same speed and are so arranged with respect to each other that they allow the respective beams of light, which they control, to pass one after the other.
  • the light coming from the disc 30 will pass 1/50 of a second; then the beam from the disc 32 will pass also 1 50 of a second; finally, the beam from the disc 38 will pass for 1/50 of a second.
  • the beam from the disc 38 also passes through certain lenses inserted in the two rotating discs 39 and 40 which are arranged one above the other and in overlapping relation, as indicated in Figure 3.
  • Each disc carries a plurality of lenses and they are so arranged with respect to each other that when a lens of ⁇ one is superimposed on a lens of the other, the respective directions of motion are at right angles when they cross each other.
  • the disc 39 is rotated rather slowly while the disc 40 is rotated at a much higher speed.
  • the discs are so placed and the focal lengths of their lenses are so computed that the real image of the point of light from the light source 33 is formed on the surface 5 of the cathode.
  • the beam of light coming from any lens of either of the discs 39 or l10 shall form a cone of much wider angle than the cone formed by the beams of light entering these lenses or entering the lens 8. This is to ensure that the point of light, which is the image of light source 33, remains constant in brightness as it is impelled to scan the surface 5 by the rotation of the two discs.
  • the scanning spot on the surface 5 may be rendered extremely small and intensely bright; moreover, the successive lines of the scanning on this screen will be exceedingly close to each other in proportion to the speed of the disc 40 with respect to that of the disc 39.
  • All the various discs may be conveniently driven from a single source of power such as a motor, the discs 30, 32, 38 and commutators 10 and 18 having the same speed of rotation.
  • the potential of the grid and anode are so arranged that if an elementalv area of Zero potential is struck by the scanning beam, then all the electrons detached will be received by the anode. If, on the other hand, an elemental area having a positive potential slightly greater than any positive potential which could be caused by the view is struck by the scanning beam, then no electrons will pass from this area to the anode. Between these two values the number of electrons reaching the anode will vary according to the potential of the element from which they are detached. As the anode receives more or less electrons, its potential will change and modulations will be imposed on the grid of the three-electrode valve of the transmitter. From this point, the transmission is carried on by known methods.
  • the steps which comprise bringing a sensitive screen to a uniform potential by projecting a beam of light on a photoelcctric electrode different from the screen, then projecting an image on the screen, and then scanning the screen.
  • a method of television which comprises first energizing the photoelectric surface of a limited area, then sensitizing the said photoelectric surface with an image of a view, then traversing said surface with a scanning beam of strong illumination and causing the photoelectric values to be impressed upon a transmitting medium and repeating these steps in the transmission of each individual image.
  • the method of television which comprises projecting an image of a scene on the sensitized cathode of a photoelectric cell, then scanning the cathode to cause the latter to send a modulated electronic current to the anode, the said anode being connected to the transmitting medium onl when the scanning beam strikes the photoe ectric area, then closing the Window of the cell, disconnecting the anode from the transmitting medium and then causing the elements of the cathode to assume a uniform potential.
  • a television method comprising subjecting a sensitized surface different from the cathode to a strong beam of light, then interrupting the beam of light, applying a potential to the anode, forming an image of the scene on the cathode, then subjecting the cathode to a scanning beam of light after connecting the anode to an amplier.
  • Television apparatus comprising a photoelectric cell having a sensitized cathode formed of photoelectric elements insulated one from the other, a grid, an anode, a window, and an additional grounded photoelectric surface, means for producing an interrupted beam of light to form an image on the cathode, means for producing an interrupted beam of light for indirectly energizing the cathode by striking the additional surface and means for producing an interrupted scanning beam of light.
  • Television apparatus comprising a photoelectric cell having a sensitized cathode, a grid and an anode, a Window, and an additional photoelectric surface, means for producing an interrupted beam of light to form an image on the cathode, means for producing an interrupted beam of light striking the additional photosensitive surface for indirectly energizing the cathode, means for producing an interrupted scanning beam of light, means for connecting the anode successively to ground, to a ⁇ source of positive potential, and to an amplifying system.
  • Television apparatus comprising a photoelectric cell having a sensitized cathode formed of a large number of photoelectric elements, a grid, an anode, a Window, and an additional grounded photoelectric surface, means for producing an interrupted beam of light to form an image on the cathode, means for producing an interrupted beam of light for indirectly energizing the cathode, means for producing an interrupted scanning beam of light and means for connecting the anode to an amplifying system.
  • Television apparatus comprising a photoelectric cell having a sensitized cathode, a grid, an anode, a Window, and an additional grounded photoelectric surface, means for producing an interrupted beam of light to form an image on the cathode, means for producing an interrupted beam of light striking the additional surface for energizing the cathode, means for producing an ininterrupted scanning beam of light and means for intermittently connecting the anode to an amplifying system.
  • Television apparatus comprising a photoelectric cell having a sensitized cathode, a grid, an anode, a Window, and an additional photoelectric electrode, means for producing an interrupted beam of light to form an image on the cathode, means for producing an interrupted beam of light striking the additional electrode for energizing the cathode, means for producing an interrupted scanning beam of light, means for connecting the anode intermittently to ground, to positive potential, and to an amplifying system.
  • a photoelectric cell comprising an evacuated vessel having a Window at one side and a photoelectric cathode at the opposite side, a grid adjacent to the cathode, an anode between the grid and the Window, a coating of photoelectric material on the inside of the cell, means for projecting a beam of light through the evacuated vessel and against the said coating, a lens system for forming an image of the scene through the Window and on the cathode and a lens s stem for producing a scanning beam of lig t through the Window and on the cathode.

Landscapes

  • Transforming Light Signals Into Electric Signals (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US480480A 1929-05-18 1930-09-08 Television Expired - Lifetime US1903113A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US20187D USRE20187E (en) 1929-05-18 Television
BE363913D BE363913A (en, 2012) 1929-05-18
US480480A US1903113A (en) 1929-05-18 1930-09-08 Television

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CA1903113X 1929-05-18
US367084A US1903112A (en) 1929-05-29 1929-05-29 Television
GB2483530A GB335995A (en) 1929-06-04 1929-06-04 Improvements in or relating to television
US480480A US1903113A (en) 1929-05-18 1930-09-08 Television

Publications (1)

Publication Number Publication Date
US1903113A true US1903113A (en) 1933-03-28

Family

ID=27427736

Family Applications (2)

Application Number Title Priority Date Filing Date
US20187D Expired USRE20187E (en) 1929-05-18 Television
US480480A Expired - Lifetime US1903113A (en) 1929-05-18 1930-09-08 Television

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US20187D Expired USRE20187E (en) 1929-05-18 Television

Country Status (2)

Country Link
US (2) US1903113A (en, 2012)
BE (1) BE363913A (en, 2012)

Also Published As

Publication number Publication date
BE363913A (en, 2012)
USRE20187E (en) 1936-12-01

Similar Documents

Publication Publication Date Title
US2654853A (en) Photoelectric apparatus
US2550316A (en) Image storage device
US2131185A (en) Electrooptical device
US2281637A (en) Cathode ray television receiver
US2460093A (en) Cathode beam transmitter tube
US2368884A (en) Television transmitting apparatus
US2213060A (en) Cathode ray tube
US2415842A (en) Electrooptical device
US2548118A (en) Art of analyzing optical images
US2917574A (en) Color television pickup system
US2381901A (en) Television transmitting system
US2681380A (en) Color television projection system
US2292437A (en) Electron image amplifier
US2270232A (en) Television receiving system
US2716203A (en) Electronic image storage tube and system
US1903113A (en) Television
US2213547A (en) Electron discharge apparatus
US2433700A (en) Phototube multiplier
US2150168A (en) Electro-optical system
US2339662A (en) Television transmitter
US2059221A (en) Television system
US2373396A (en) Electron discharge device
US2150159A (en) Electro-optical system
US2490740A (en) Image tube
US2059222A (en) Television apparatus