US2151797A - Photoelectric tube - Google Patents

Photoelectric tube Download PDF

Info

Publication number
US2151797A
US2151797A US150456A US15045637A US2151797A US 2151797 A US2151797 A US 2151797A US 150456 A US150456 A US 150456A US 15045637 A US15045637 A US 15045637A US 2151797 A US2151797 A US 2151797A
Authority
US
United States
Prior art keywords
silver
cathode
caesium
tubes
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
US150456A
Other languages
English (en)
Inventor
Jr Charles H Prescott
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
Original Assignee
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
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US150456A priority Critical patent/US2151797A/en
Priority to FR839858D priority patent/FR839858A/fr
Application granted granted Critical
Publication of US2151797A publication Critical patent/US2151797A/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
    • H01J40/00—Photoelectric discharge tubes not involving the ionisation of a gas
    • H01J40/02—Details
    • H01J40/04—Electrodes
    • H01J40/06—Photo-emissive cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/12—Manufacture of electrodes or electrode systems of photo-emissive cathodes; of secondary-emission electrodes

Definitions

  • This invention relates to photoelectric tubes and more particularly to cathodes therefor and methods of making such cathodes.
  • Photoelectric tubes are now used for a great variety of purposes among which may be mentioned the matching of colors and television of colored objects. For these purposes it is sometimes advantageous to utilize a photoelectric tube having a spectral response characteristic approximating that of the human eye. As is Well known, the average human eye is most responsive to greenish-yellow light, that is, to light of wave-lengths in the neighborhood of 5500 A. U.
  • a photoelectric cathode manufactured in accordance with this invention is stable under relatively high temperatures and in a glass envelope has a spectral response approximately like that of the human eye.
  • a typical cathode according to this invention comprises a roughened silver plate carrying a thin layer of an intimate mixture of finely divided caesium, caesium sulphide and metallic silver on the exposed surface of which caesium is adsorbed.
  • Fig. 1 shows the structure of a completed photoelectric tube according to this invention.
  • Fig. 3 is a schematic electric circuit used in processing such tubes.
  • the photoelectric tube illustrated in Fig. 1 comprises a glass bulb 5 having a reentrant stem 30 6 sealed therein.
  • the stem 6 is provided with a press 7 in which are sealed cathode support wires 8, 8a and 8b, an anode wire 9, lead-in wires l0 and II connected to support wire 8 and anode wire 9, respectively.
  • a cathode l2 comprises a 55 semi-cylindrical silver plate, the straight edges of which are rolled around the support wires 8 and 8a and to the lower rear edge of which support wire 8b is connected.
  • Also supported by wires sealed into the press I is a heavy copper wire l3 which partially encircles the stem 6 and 5 between the ends of which is a metallic capsule M.
  • This capsule l4 encloses a mixture for producing caesium vapor when heated.
  • a nickel shield i 5 is supported, also from wires sealed into the press 1, between the capsule H and the 10 press l and the concave surface of cathode I 2.
  • the stem 6 is provided with an exhaust tube It.
  • a coil I1 is arranged to induce current in the copper wire l3 and capsule It for heating the mixture within the capsule to its reaction teml5 perature.
  • This coil ll is used only during the processing of the cathode l2 and is shown in partial section in Fig. 1. A portion of the glass bulb 5 is shown removed for clearness of illustration.
  • the electrode and accessory structure carried by the stem 6 is fabricated before the stemis sealed into the glass tube 5.
  • the cathode plate It is formed from a polished silver sheet of a high degree of purity which has a clean mirror finish. The formed cathode is washed and reduced in hydrogen. The concave surface of the cathode has an area of about 2 square inches.
  • the anode 9 is a nickel wire.
  • the caesium producing mixture within the capsule M is in the form of a compressed pellet which is composed of approximately 5 milligrams of caesium chromate, Cs2CrO4, 32 milligrams of chromic oxide, CraOa, and 13 milligrams of powdered aluminum, Al. 'These in- 85 gredients are carefully prepared, finely pulverized and thoroughly mixed in proper proportions before being formed into pellets.
  • the pumping station illustrated in Fig. 2 is adapted for the processing of four tubes concurrently.
  • the tubes 5 are sealed to a glass header 2G by exhaust tubes [6.
  • This header 20 runs through an oven 2! which comprises a base 22 carrying end supports 23, on the upper ends of which is a metallic cap 24.
  • An electric heater 25 between the supports 23 is surmounted by a removable cover 26 carrying four chimneys 27.
  • This cover is provided with handles 28.
  • the heater 25, cover 26 and chimneys 21 may be m raised as a unit so that the chimneys surround the bulbs 5.
  • Each chimney is provided with a slidable baffle (not shown) to control the convection air currents flowing therethrough. With the cover 26 and chimneys 21 removed, the heater cc 25 may be raised up against the cap 24 to complet'ely surround the bulbs 5.
  • the header 2!! is connected to a pumping apparatus comprising a liquid air trap 29 two McLeod gauges 30 and 3
  • a pumping apparatus comprising a liquid air trap 29 two McLeod gauges 30 and 3
  • three gas supply units 35, 36 and 31 are connected to the pumping apparatus.
  • Each unit comprises a flexible coiled glass tube 38 associated with a gas container 33 through a mercury seal surrounding a pair of porous plugs of Lavite" which when brought together permit gas to pass from the container 33 to the bulbs through the glass coil 38.
  • An ionization manometer 40 is connected to the other end of the header 20.
  • FIG. 3 An electrical circuit used during the processing of four tubes while they are sealed on the pumping station is illustrated in Fig. 3.
  • This circuit comprises conductors 50 adapted to be connected to a direct current source (not shown) and a potentiometer 5
  • a potential may be impressed on any one of tubes 5 by closing the lower contacts of switch 53 which is individual to such tube.
  • is impressed through the upper contacts of all of switches 53 in series on condensers 54 which have a total capacitance of 5 mlcrofarads.
  • Condensers 54 can then be discharged through any one of tubes 5 by closing the lower contacts of the corresponding switch 53.
  • is indicated by voltmeter 56.
  • the current flowing through tubes 5 during a later stage of the processing is indicated by an ammeter 53 which may be connected into the circuit by inserting plug 51 into jack 55.
  • the vacuum pump is turned on.
  • the liquid air trap is cooled with a mixture of Cellosolve acetate" and solidified carbon dioxide.
  • the manometer 40 is turned on.
  • the heater 25, without the cover 25 and chimneys 21, is raised to engage the cap 24.
  • the current is turned on to bring the oven temperature up to 400 C. and maintained until the manometer shows a pressure of 5X10- mm. of Hg (millimeters of mercury) or lower when the current is shut off and the oven allowed to cool.
  • Slow leaks anywhere in the system are indicated if the pressure is not less than 2 mm. of Hg when the tubes are cooled to room temperature. If leaks are indicated they should be eliminated before the processing proceeds.
  • This treatment removes occluded gases from the tubes but does not cause any chemical reaction in the caesium pellet.
  • the pumping station is then flushed with oxygen from gas supply unit 35 until a clear green haze is obtained in the manometer 40 which indicates suflicient purity of the oxygen.
  • the mercury cut-off 33 is now closed to cut off the vacuum pumps and the manometer 40 turned oil. Additional oxygen is admitted to a pressure of 2.2 mm. of Hg as indicated by McLeod gauge 33. is set in its lower position and the potentiometer 5
  • This treatment with hydrogen sulphide gas produces a thin layer of silver sulphide on the concave surface of each cathode l2.
  • a glow discharge occurs in the associated tube 5 and the cathode
  • the cathodes l2 are now in condition to be treated with caesium vapor under suitable temperature conditions.
  • a source of high frequency current (not shown) is connected to the coils II in succession to flash" the caesium capsules, that is, to induce sufllcient current in the copper wire l3 and capsule H to start a. chemical reaction of the ingredients of the caesium pellet. The exothermic reaction which follows develops a large amount of heat and causes the immediate and complete expulsion of all of the caesium.
  • the high frequency source is disconnected as soon as the reaction starts.
  • the caesium travels in straight lines from the capsule l4 and is condensed on the glass walls of the bulb 5.
  • the shield I5 prevents the hot caesium vapor from impinging on the cathode surface.
  • This shield I5 is so shaped that it lies substantially parallel to the magnetic lines of force produced by the high frequency current in the coil I I and therefore is not heated to any great extent by eddy currents induced therein.
  • stem heaters (not shown) are inserted around the stems of the tubes 5. Thermocouples are placed against each bulb 5 at the surface pposite the stem to indicate temperatures. The cover 26 with the chimneys 27 are placed on the heater 25 and the whole raised until a chimney 27 surrounds each bulb 5.
  • the stem heaters are turned on first and after two minutes the heater Z is turned on to quickly bring up the temperature of the convection air currents flowing past the bulbs 5. When the hottest bulb reaches a temperature of 150 C. the heater is regulated to hold this temperature for five minutes. At the end of this five-minute period the heater 25 is again regulated to raise the temperature of the air currents to quickly bring the temperature of the hottest bulb 5 up to 225 C. The heater 25 is then regulated to hold this temperature until the cathode surface of each tube has reached the proper sensitivity.
  • the sensitivity may be indicated by the ammeter 58 when connected into the circuit of Fig. 3 by the insertion of plug 5'5 into jack 55.
  • Each cathode l2 may be illuminated by a source of light (not shown).
  • the potentiometer 55 is adjusted to give a voltage of 50 volts as shown on voltmeter 56.
  • Switch 52 is closed in its lower position.
  • the sensitivity of each tube 5 will be indicated by the ammeter 58 if the corresponding switch 53 is closed in its lower position.
  • the tubes 5 are tested from time to time while illuminated and the hot air treatment is continued until the photoelectric current tends to decrease. As each tube reaches its proper sensitivity the air current for that tube is cut off. When all of the tubes have reached the proper sensitivity, the chimneys 2! are lowered and the bulbs allowed to cool to room temperature with the pumping apparatus still on.
  • Stable cathodes may be produced by varying considerably the specific process described in detail hereinbefore. However, in all such variabions the silver surface is so treated with hydrogen sulphide gas as to produce a layer of silver iulphide on the cathode, which layer is subjected :o heated caesium vapor to reduce at least some if the silver sulphide to form caesium sulphide ind finely divided metallic silver.
  • the remaining free caesium is in a finely n vided state.
  • it may be so finely divided that the particles are approaching atomic dimensions, so that the behavior of an atom will depend more upon the other ingredients in the cathode layer than upon neighboring atoms of caesium.
  • the cathode therefore, may be said to comprise a mixture of finely divided caesium sulphide and metallic silver throughout which mixture is adsorbed free caesium.
  • Some of the caesium also may well be alloyed or absorbed in the free silver particles or underlying rough silver surface.
  • the roughened silver surface may be produced in other ways than by oxidation and reductior Jf the silver oxide.
  • the treated silver surface may also consist of a layer of silver on a plate of another metal, such as copper or nickel.
  • Stable cathodes may also be formed by subjecting the sulphided silver surface to the vapor of others of the alkali metals, rubidium, lithium, potassium and sodium.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Glass Compositions (AREA)
US150456A 1937-06-26 1937-06-26 Photoelectric tube Expired - Lifetime US2151797A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US150456A US2151797A (en) 1937-06-26 1937-06-26 Photoelectric tube
FR839858D FR839858A (fr) 1937-06-26 1938-06-25 Tubes photoélectriques

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US839858XA 1937-06-26 1937-06-26
US150456A US2151797A (en) 1937-06-26 1937-06-26 Photoelectric tube

Publications (1)

Publication Number Publication Date
US2151797A true US2151797A (en) 1939-03-28

Family

ID=26769996

Family Applications (1)

Application Number Title Priority Date Filing Date
US150456A Expired - Lifetime US2151797A (en) 1937-06-26 1937-06-26 Photoelectric tube

Country Status (2)

Country Link
US (1) US2151797A (fr)
FR (1) FR839858A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2835841A (en) * 1955-09-08 1958-05-20 Gen Electric Getter support structure
US3936532A (en) * 1974-02-08 1976-02-03 Oregon Graduate Center For Study And Research Activation of thin wire emitters for field ionization/field desorption mass spectrometry
US4126489A (en) * 1973-07-17 1978-11-21 Varian Associates, Inc. Method of making cathode heaters
US11449904B1 (en) 2010-11-11 2022-09-20 Ikorongo Technology, LLC System and device for generating a check-in image for a geographic location

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2835841A (en) * 1955-09-08 1958-05-20 Gen Electric Getter support structure
US4126489A (en) * 1973-07-17 1978-11-21 Varian Associates, Inc. Method of making cathode heaters
US3936532A (en) * 1974-02-08 1976-02-03 Oregon Graduate Center For Study And Research Activation of thin wire emitters for field ionization/field desorption mass spectrometry
US11449904B1 (en) 2010-11-11 2022-09-20 Ikorongo Technology, LLC System and device for generating a check-in image for a geographic location

Also Published As

Publication number Publication date
FR839858A (fr) 1939-04-13

Similar Documents

Publication Publication Date Title
US2161458A (en) Luminescent screen
US2417361A (en) Apparatus for producing cold cathode fluorescent lamps or the like
US2151797A (en) Photoelectric tube
US2217205A (en) Photoelectric tube
US2393264A (en) Photoelectric device and the manufacture thereof
US2178227A (en) Photoelectric tube
US2198650A (en) Photoelectric tube
GB477462A (en) Improvements in or relating to metallic electric conductors sealed through quartz
US2208113A (en) Manufacture of lamps
US2097467A (en) Photoelectric tube
KR840000969A (ko) 잔광을 없애기 위한 음극선관의 마운트 어셈블리의 처리방법
GB411669A (en) Improvements in and relating to gaseous electric discharge devices
US2208129A (en) Photoelectric tube
US2020722A (en) Gaseous electric discharge device
US789515A (en) Leading-in conductor.
US3005674A (en) Method of dosing mercury vapor lamps
US3909308A (en) Production of lead monoxide coated vidicon target
US2184323A (en) Cathode activation and degassing
US1935939A (en) Photo-electric tube and method of producing the same
US2930872A (en) Glow switch
US1647591A (en) Gaseous-discharge lamp
US1804467A (en) Electric discharge device
US2369591A (en) Incandescent electric lamp
US2102760A (en) Photoelectric tube
US1720172A (en) Electron-discharge tube and method of manufacturing the same