US3214627A - Rapid-start cathode-ray tubes - Google Patents

Rapid-start cathode-ray tubes Download PDF

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Publication number
US3214627A
US3214627A US174819A US17481962A US3214627A US 3214627 A US3214627 A US 3214627A US 174819 A US174819 A US 174819A US 17481962 A US17481962 A US 17481962A US 3214627 A US3214627 A US 3214627A
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United States
Prior art keywords
cathode
elements
potential
heater element
tube
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Expired - Lifetime
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US174819A
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English (en)
Inventor
Yamamoto Hiroshi
Takanashi Yukio
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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Publication date
Application filed by Tokyo Shibaura Electric Co Ltd filed Critical Tokyo Shibaura Electric Co Ltd
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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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/485—Construction of the gun or of parts thereof
    • 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
    • H01J29/04—Cathodes

Definitions

  • Cathode-ray tubes generally have a cathode structure including a cylindrical cup coated with an electron-emitting material and enclosing a heater wire for indirect heating thereof.
  • a cathode structure having a substantial heat capacity, the tube employing it may start or be set into proper operation only more than ten seconds after it has been turned on. Therefore, with a television receiving set having a cathode-ray tube of such conventional design, the voice only is first reproduced when the set is turned on, the picture being formed only after a considerable time has elapsed. This phenomenon is conspicuous especially with a transistor type receiving set, since the voice is produced substantially at the same time that the set is turned on with the picture noticeably delayed in showing itself.
  • the present invention is intended to overcome the above deficiency of conventional cathode-ray tubes especially by providing an improved cathode structure adapted to enable the tube to start rapidly.
  • a rapid'start type cathode-ray tube characterized by a cathode structure including two cathode heater elements adapted to be independently energized and deenergized.
  • FIG. 1 is a fragmentary side elevation, partly in section, showing the essential part of the cathode structure of the inventive cathode-ray tube and the connection between the heater elements and base or terminal pins of the tube in an enlarged scale;
  • FIG. 2 is a schematic showing of one example of the connection between the heater terminal pins of the tube and the voltage source therefor;
  • FIG. 3 is a fragmentary side elevation, partly in section, of another example of the connection between the auxiliary heater element and the terminal pins of the tube.
  • numeral 1 designates a cathode cup in the form of a bottomed metal cylinder having an end face coated with electron-emitting material; numeral 2, an insulating disc or flange fitted around the cathode cup 1; numeral 3, a main coiled heater element of a larger diameter inserted in said cathode cup; and numeral 4, an auxiliary folded-back heater element inserted in the main heater element 3.
  • the two heater elements are each formed of a wire of metal having a high melting point, such as tungsten, and coated with insulating material such as alumina.
  • the main heater element serves to heat the cathode so as to maintain it at a predetermined operating temperature while the auxiliary heater element serves to heat and rapidly raise the temperature of the cathode when the cathode-ray tube is being started.
  • the opposite ends of the main heater element 3 are respectively connected to terminal or base pins 6 and 7 secured to the tube base while the opposite ends of the auxiliary heater element 4 are connected to one of said terminal pins 7 and a further terminal pin 8, respectively.
  • the main heater element 3 is energized by applicaswitch 11 are operatively connected with each other in a tion thereon of a rated voltage enough to maintain the cathode at its predetermined operating temperature, while the auxiliary heater element 4 is supplied with a sufliciently high voltage to rapidly heat the cathode. It will be appreciated that the cathode is thus rapidly heated under the action of the main and auxiliary heater elements to a desired elevated temperature providing for rapid starting of the tube.
  • the auxiliary heater element is deenergized so that the cathode is maintained at its predetermined operating temperature without any danger of being overheated.
  • the auxiliary heater element is disposed within the main heater coil in spaced apart relation with the cathode cup and is held at the same potential as the main heater, the insulator coating on the auxiliary heater may not only be made in an extremely small thickness to reduce its heat capacity but also be heated to any desired elevated temperature without the danger of its puncturing. This is quite an important fact which makes it possible to design the auxiliary heater element as required to heat the cathode rapidly.
  • the auxiliary heater element took the form of a folded-back tungsten wire having a current capacity of 150 ma. at 6.3 volts and carrying a thin alumina coating of approximately 0.03-millimeter thickness.
  • the main heater element was formed of a coiled tungsten wire having a rated capacity of ma. at 6.3 volts.
  • 21 thick alumina coating of approximately 0.07 millimeter thickness was deposited around the coil by spraying to give a sufiicient dielectric strength thereto.
  • the heater assembly was then inserted in a cathode cup to form a cathode-ray tube with heater ratings of 75 ma.
  • auxiliary heater element having a limited heat capacity is heated to a very high temperature in quite a short period of time so that the cathode is rapidly heated to start the tube in a time as short as approximately 2 to 3 seconds.
  • the current through the auxiliary heater element is cut Off and the cathode is held at the predetermined operating temperature to mainaint the tube in operation.
  • the inventive cathode-ray tube when employed for example in a television set can markedly enhance its value as a merchandise.
  • FIG. 2 is a schematic wiring diagram for the heater means of the inventive cathode-ray tube.
  • the terminal pins of the tube connected with the heater elements therein are also connected with a voltage source 9 to obtain respective desired terminal voltages.
  • the circuit of the terminal pin 7, which is connected to both the main and auxiliary heater elements, includes a series-connected switch 10.
  • the circuit of the terminal pin 8, which is connected to the opposite end of the auxiliary heater element includes a series-connected time-limit switch 11 of suitable construction. The switch 10 and the time-limit suitable manner so that the latter 11 is automatically opened a desired length of time, as for example three seconds, after the main and auxiliary heater elements have both been activated.
  • one end of the auxiliary heater element 4 and the associated terminal pin 8 may be interconnected by way of a heatresponsive switch 12 for example including a bi-metallic element, arranged to interrupt the current flow to the auxiliary heater element in response to the heat transmitted therefrom to the switch.
  • a heatresponsive switch 12 for example including a bi-metallic element, arranged to interrupt the current flow to the auxiliary heater element in response to the heat transmitted therefrom to the switch.
  • the auxiliary heater element may be connected to the terminal pins for the main heater instead of being provided with separate terminal pins for the auxiliary heater itself. This arrangement has an advantage that it enables the cathode-ray tube according to the present invention to be employed in the existing appliances, which have previously employed a conventional cathode-ray tube.
  • auxiliary heater element is inserted in a main heater element in the form of a coil of a larger diameter, as described above.
  • an auxiliary heater element carrying an insulator coating of substantial thickness may be inserted in the cathode cup in side-by-side relation with the main heater element.
  • the main heater element may take the form of a coil of limited diameter or a straight folded wire.
  • the auxiliary heater element may be provided with separate terminal pins independently of those for the main heater element and that the auxiliary heater may also be formed into a coil.
  • a cathode-ray tube indirect heater cathode assembly for providing rapid start of the tube characterized by a cathode structure including two cathode heater elements adapted to be independently energized and de-energized; a cathode cup adapted to contain both elements; a pair of leads extending from each element beyond the cup; a plurality of terminals in connection with the leads whereat a first source of potential may be applied to one of the elements, and a second source of potential may be applied to the other of the elements; said other of said elements adapted to maintain the cathode at normal oper- 4. ating temperature; said one of the elements being adapted to produce greater quantities of heat than the other element; means for simultaneously applying the first and second sources of potential to energize both elements; and means for disconnecting one source of potential when the cathode-ray tube has started.
  • a cathode-ray tube indirect heater cathode assembly for providing rapid start of the tube characterized by a cathode structure including two cathode heater elements adapted to be independently energized and dcenergized; a cathode cup adapted to contain both elements; a pair of leads extending from each element beyond the cup; a plurality of terminals in connection with the leads whereat a first source of potential may be applied to one of the elements, and a second source of potential may be applied to the other of the elements; said other of said elements adapted to maintain the cathode at normal operating temperature; said one of the elements being adapted to produce greater quantities of heat than the other element; means for simultaneously applying the first and second sources of potential to energize both elements; and thermally operable means responsive to the heat generated by said elements for disconnecting said first source of potential when normal operating temperature is attained.

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  • Electrodes For Cathode-Ray Tubes (AREA)
US174819A 1961-02-24 1962-02-21 Rapid-start cathode-ray tubes Expired - Lifetime US3214627A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP778461 1961-02-24

Publications (1)

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US3214627A true US3214627A (en) 1965-10-26

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US (1) US3214627A (en, 2012)
NL (1) NL275209A (en, 2012)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE745329C (de) * 1941-02-13 1944-03-24 Telefunken Gmbh Indirekt geheizte Kathode
US2460883A (en) * 1947-11-10 1949-02-08 Rca Corp Means for saving power
US2488948A (en) * 1947-11-28 1949-11-22 Bell Telephone Labor Inc Repeatered transmission system, including multifilament amplifiers
US2533493A (en) * 1942-02-20 1950-12-12 Motorola Inc Portable radio device
US2753480A (en) * 1952-10-11 1956-07-03 Rca Corp Indirectly heated cathode structure and method of assembly
GB787458A (en) * 1953-12-10 1957-12-11 Edison Swan Electric Co Ltd Improvements relating to indirectly heated cathodes for thermionic valves
US2870366A (en) * 1951-10-13 1959-01-20 Philips Corp Electric discharge tube of the kind comprising a cathode of the indirectly heated type
US3087082A (en) * 1960-02-09 1963-04-23 Rca Corp Cathode-ceramic assembly for electron guns and method of making

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE745329C (de) * 1941-02-13 1944-03-24 Telefunken Gmbh Indirekt geheizte Kathode
US2533493A (en) * 1942-02-20 1950-12-12 Motorola Inc Portable radio device
US2460883A (en) * 1947-11-10 1949-02-08 Rca Corp Means for saving power
US2488948A (en) * 1947-11-28 1949-11-22 Bell Telephone Labor Inc Repeatered transmission system, including multifilament amplifiers
US2870366A (en) * 1951-10-13 1959-01-20 Philips Corp Electric discharge tube of the kind comprising a cathode of the indirectly heated type
US2753480A (en) * 1952-10-11 1956-07-03 Rca Corp Indirectly heated cathode structure and method of assembly
GB787458A (en) * 1953-12-10 1957-12-11 Edison Swan Electric Co Ltd Improvements relating to indirectly heated cathodes for thermionic valves
US3087082A (en) * 1960-02-09 1963-04-23 Rca Corp Cathode-ceramic assembly for electron guns and method of making

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NL275209A (en, 2012)

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