US1837746A - Photo-electric tube - Google Patents

Photo-electric tube Download PDF

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Publication number
US1837746A
US1837746A US258706A US25870628A US1837746A US 1837746 A US1837746 A US 1837746A US 258706 A US258706 A US 258706A US 25870628 A US25870628 A US 25870628A US 1837746 A US1837746 A US 1837746A
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US
United States
Prior art keywords
photo
metal
vacuum
electrode
magnesium
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
US258706A
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English (en)
Inventor
Vladimir K Zworykin
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.)
Westinghouse Electric Corp
Original Assignee
Westinghouse Electric 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 NL25989D priority Critical patent/NL25989C/xx
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US258706A priority patent/US1837746A/en
Priority to GB6870/29A priority patent/GB307082A/en
Application granted granted Critical
Publication of US1837746A publication Critical patent/US1837746A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J40/00—Photoelectric discharge tubes not involving the ionisation of a gas
    • H01J40/02—Details
    • H01J40/04—Electrodes
    • H01J40/06—Photo-emissive cathodes

Definitions

  • My invention relates to vacuum electrical discharge devices and particularly to devices of the foregoing character in which discharge is adapted to be varied in accordance with the intensity of light falling upon a predetermined surface within the apparatus. De vices of such character are commonly called photo-electric cells.
  • One object of my invention is to provide a photo-electric cell which shall be sensitive to small variations in the amount of light to which it is subjected.
  • Another object of my invention is to provide a photo-electric cell in which the intensity of the electrical discharge corresponding to a given incident illumination shall remain invariable over a long period of time.
  • Another object of my invention is to provide a photo-electric cell in which the maximum response lies in the yellow and red part of the spectrum.
  • Still another object of my invention is to provide a method whereby the curve connecting electron emissivity with wave length of incident light may be given a wide variety of forms and the maximum thereof caused to occur at almost any wave length desired.
  • a further object of my invention is to provide a photo-electric cell which shall be simple and cheap to manufacture and which will require only methods of manufacture and apparatus for producing the requisite Vacuum which are well known in the vacuum-tube art.
  • FIG. 2 is a similar view of a vacuum tube embodying another modification of my invention.
  • a photo-electric cell of the usual early type comprised a surface of an alkali metal, such as potassium, in electrical contact with one of the terminals and adapted to emit electrons in accordance with the amount of light to which it was subjected. Such surfaces 1928. Serial No. 258,706.
  • the film will withstand a temperature far in excess of the normal melting point of the metal composing it, and that the wave length for maximum sensitivity has been shifted from its normal position corresponding to the work function of the superposed metal, when used as in the prior art, toward the low frequency end of the spectrum.
  • Fig. 1 modification comprises a vacuum-type container which is provided with a stem 2 through which an inleading wire 3 is sealed.
  • the inleadin wire 3 supports a metallic electrode 4, pre erably of annular form, to which a small piece of magnesium 5 is attached.
  • a sleeve 6 projects a short distance above the stem 2, and a disk 7 of glass may be aflixed to the wire 3 a short distance above the end of the sleeve 6.
  • an inleading wlre 8 is sealed through the lass wall and bent to lie closely against it or a considerable distance.
  • a flange 9 is provided on the stem 2 and arranged to nearly fill the cross section of the neck of the cell below the point where the wire 3 is sealed therein.
  • the tube constructed in the foregoing manner is first exhausted by methods well known in the vacuum-tube art.
  • the tube. is heated to as hi h a temperature as the glass wall there'- It may then be sealed off from the vacuum pump.
  • the flange 9 prevents magnesium om depositing in the neck of the cell below esa-r40 it and thus confines that material to the chamber walls in the vicinity of the wire of the lead 8, the location most desired for it.
  • the sleeve 6 and the flange 7 prevent the vapor of magnesium from depositing on the inner end of the cell 2 and thereby insure the insulation of the lead 3 from the magnesium coating.
  • magnesium as the metal to be vaporized
  • other metals such as those of the alkali earth group, and even aluminum alloys and the well known alloy misch metal, maybe utilized for this purpose.
  • the metal to be used depends upon, convenience of manufacture and the particular characteristics of the photo-electric cell which are desired.
  • a small amount of the vapor of a metal or metals may be introduced, after a high vacuum has been produced in the cell, by heating a small tube containing the desired metal.
  • the metals chosen should be such as have a maximum on their emissivity versus wave length curve in the region of the wave length of the radiation to which response is desired.
  • the metals chosen should be such as have a maximum on their emissivity versus wave length curve in the region of the wave length of the radiation to which response is desired.
  • potassium, rubidium and caesium which have maxima of emissivity in the visible region are usually preferable for use.
  • a way which I prefer, however, consists in painting a weak solution of an alkali-metal trinitride such as caesium trinitride on the portion of the electrode 4 considerably removed from the magnesium 5.
  • Fig. 2 When it is desired to decompose a salt in order to furnish the alkali metal, it will usually be found preferable to employ the cell illustrated in Fig. 2.
  • This cell is similar to that shown in Fig. 1 except that it has a pair of additional inleading wires 11 and 12 sealed through the stem. 2. Between one of these wires 11 and a suitable point of the inleading wire 3, is connected a filament 13 which is suitable for heating to provide an incandescent cathode; The other inleading wire 12 is provided with a small auxiliary electrode plate 14, upon which a small amount of the required alkali-metal salt has been deposited. When it is desired to decompose the latter, the filament 13 is heated to incandescence, and the plate 14 is supplied with a positive potential.
  • the salt is bombarded with elec-' trons and decomposes to furnish the necessary alkali metal.
  • the decomposition of the 1 salt. in this manner may be carried out subsequent to the deposition of the magnesium, but a small portion of the cell wall should afterward be heated in order to clear a window to permit entrance of light.
  • the desired inert gas which may, for example, be argon, helium or neon, may be introduced before the cell is sealed off from the pump.
  • vaporization of the magnesium in the manner previously described causes it to act as a purif ing agent to remove gaseous impurities evo ved when the lass of the tube is heated in sealing it off om the pump.
  • the noble gases appear not to be carried down by the condensation of the magnesium in anything like an equal degree to the gaseous impurities aforesaid which it is desired to remove.
  • a photo-sensitive device comprisin a vacuum-type container havin ing a metal of the alka a surace 2.
  • a photo-sensitive device' comm-fig a vacuum-type container having a ace therein covered with magnesium and metallic caesium su r osed on said magnesium to form a cath d and a cooperating electrode therefor.
  • a 3 In combination a vacuum-type container, an electrode adapted to be eated by a high-frequency magnetic field, magnes1 metal on one portion of said first electrode caesium trinitride on another portion of first electrode and an inleading wire in con-' tact with the surface within said container.
  • a photo-sensitive device comprising a vacuum-type container, an annular electrode therein, a second electrode in operative relationship with said first electrode magnesium metal on a portion of said first electrode and caesium trinitride on another portion of said first electrode.
  • a photo-sensitive cathode comprising the ste of depositfine eartgrou within an envelope-and vaporizing a meta of the alkali group thereon.
  • a photo-sensitive device comprising a plurality of cooperating electrodes, a plurality of thin layers of photo-electric material on one of said electrodes, the substances forming said layers having a maximum on their emlssivit versus wave length curve in the re 'on o the visible spectrum.
  • a photo-sensitive device comprisin a plurality of cooperating electrodes, a p urality of thin layers of various alkali metals on said electrode, said metals having a maximum on their emissivity versus wave length curve in the region of the visible spectrum.
  • a photo-sensitive device comprisin a pigality of cooperating electrodes, a t in comprising two or more substances on one of said electrodes, said substances individually having maximum electron emissivit at different places on the visible s ectrum, t e electron emissivity curve of said film being substantially flat between the maximum electron emissivity of said substances individually.

Landscapes

  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
US258706A 1928-03-03 1928-03-03 Photo-electric tube Expired - Lifetime US1837746A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL25989D NL25989C (enrdf_load_stackoverflow) 1928-03-03
US258706A US1837746A (en) 1928-03-03 1928-03-03 Photo-electric tube
GB6870/29A GB307082A (en) 1928-03-03 1929-03-02 Improvements relating to photo-electric cells

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US307082XA 1928-03-03 1928-03-03
US258706A US1837746A (en) 1928-03-03 1928-03-03 Photo-electric tube

Publications (1)

Publication Number Publication Date
US1837746A true US1837746A (en) 1931-12-22

Family

ID=26706375

Family Applications (1)

Application Number Title Priority Date Filing Date
US258706A Expired - Lifetime US1837746A (en) 1928-03-03 1928-03-03 Photo-electric tube

Country Status (3)

Country Link
US (1) US1837746A (enrdf_load_stackoverflow)
GB (1) GB307082A (enrdf_load_stackoverflow)
NL (1) NL25989C (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2462245A (en) * 1942-08-25 1949-02-22 Bell Telephone Labor Inc Space discharge device
US2692348A (en) * 1951-06-19 1954-10-19 Westinghouse Electric Corp Discharge device and electrode
US3622217A (en) * 1969-06-30 1971-11-23 Xerox Corp Light producing system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2462245A (en) * 1942-08-25 1949-02-22 Bell Telephone Labor Inc Space discharge device
US2692348A (en) * 1951-06-19 1954-10-19 Westinghouse Electric Corp Discharge device and electrode
US3622217A (en) * 1969-06-30 1971-11-23 Xerox Corp Light producing system

Also Published As

Publication number Publication date
GB307082A (en) 1930-05-29
NL25989C (enrdf_load_stackoverflow)

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