US3883767A - Heater for fast warmup cathode - Google Patents

Heater for fast warmup cathode Download PDF

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Publication number
US3883767A
US3883767A US440684A US44068474A US3883767A US 3883767 A US3883767 A US 3883767A US 440684 A US440684 A US 440684A US 44068474 A US44068474 A US 44068474A US 3883767 A US3883767 A US 3883767A
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United States
Prior art keywords
heater
cathode
legs
insulating coating
coiled body
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Expired - Lifetime
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US440684A
Inventor
William E Buescher
Donald R Kerstetter
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GTE Sylvania Inc
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GTE Sylvania Inc
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Publication date
Application filed by GTE Sylvania Inc filed Critical GTE Sylvania Inc
Priority to US440684A priority Critical patent/US3883767A/en
Priority to DE2504673A priority patent/DE2504673C3/en
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Assigned to NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP. reassignment NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP. ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATENTS AND APPLICATIONS, SUBJECT TO CONDITIONS AND LICENSES EXISTING AS OF JANUARY 21, 1981. (SEE DOCUMENT FOR DETAILS). Assignors: GTE PRODUCTS CORPORATION A DE CORP.
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Expired - Lifetime legal-status Critical Current

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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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/04—Cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/22—Heaters

Definitions

  • This invention relates to heaters for fast warmup cathodes and more particularly to heaters for use in the cathodes of television picture tubes.
  • Such a cathode comprises basically a cup-shaped cap having electron emissive material on the closed end thereof and a cathode stack which is attached to the cap ,by low heat conducting ribbons.
  • This structure works extremely well for its designed purpose but could be improved even further if heat loss could be minimized from the heater encompassed therewithin.
  • Still another object of the invention is the provision of a heater for a fast warmup cathode which has minimized heat loss.
  • a heater which comprises an electrically conductive core substantially coveredby an electrically insulating material.
  • the heater is formed to provide a coiled body portion with a pair of extending legs.
  • the height of the coiled body portion is small compared to the legs and to minimize heat loss from the legs the thickness of the insulating material thereon is substantially greater than that of the coiled body portion.
  • FIGURE is a cross-sectional elevational view of a heater constructed in accordance with the invention mounted within a suitable cathode.
  • a fast warmup cathode 10 comprising a top cap 12 which is substantially cup shaped and includes a closed end 14 having a peripheral'side wall 16 defining a hollow interior 18.
  • Top cap 12 is supported by a plurality of minimum contact areas 20 formed as part of a hollow cathode sleeve 22.
  • a heater 24 having an electrically conductive core 26 of a suitable material such as tungsten or molybdenum, surrounded by an electrically insulating coating 28, of a suitable material, such as alumina is positioned within the cathode 10.
  • the heater 24 is formed to provide a coiled body portion 30, which is of small height compared with the height of the heater, which body portion is encompassed within the hollow interior 18 of top cap 12.
  • a pair of legs 32 extend from body 30 through sleeve 22. To minimize heat loss from the extended pair of legs 32 the electrically insulating coating thereon is of much greater thickness than the coating on coiled body portion 30. To be effective the leg coating should be at least 300% and preferably 400% thicker than that on body portion 30.
  • the terminal ends of legs 32 are left bare of insulation so that electrical connection can be made thereto.
  • a heater for a fast warmup cathode comprising: a metallic, electrically conductive core; and an electrically insulating coating surrounding said core; said heater being formed to provide a coiled body having a pair of legs extending therefrom, the height of said coiled body being small compared with the length of said legs; the insulating coating on said pair of legs having a thickness about 400% greater than the thickness of the insulating coating on the coils of said coiled body portion.

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  • Electrodes For Cathode-Ray Tubes (AREA)
  • Solid Thermionic Cathode (AREA)

Abstract

Heat loss from a fast warmup cathode heater is minimized by keeping the coiled body portion of the heater small in relation to the length of the heater legs and by increasing the thickness of the insulating coating on the legs by a factor of about 400% over that on the coils.

Description

United States Patent 1 1 Buescher et al.
1451 May 13,1975
[ HEATER FOR FAST WARMUP CATHODE {75] Inventors: William E. Buescher; Donald R.
Kerstetter, both of Emporium, Pa.
[73] Assignee: GTE Sylvania Incorporated,
Stamford, Conn.
[22] Filed: Feb. 8, 1974 [21] Appl. No.: 440,684
2/1970 Katz 313/337 X l/197l Bakker et al. 313/337 Primary ExaminerSaxfield Chatmon, Jr. Atrorney, Agent, or FirmNorman J. OMalley; William H. McNeil]; Cyril A. Krenzer [57] ABSTRACT Heat loss from a fast warmup cathode heater is minimized by keeping the coiled body portion of the heater small in relation to the length of the heater legs and by increasing the thickness of the insulating coating on the legs by a factor of about 400% over that on the coils.
2 Claims, 1 Drawing Figure PATENTED W I 31975 l a: .......m\.....
HEATER FOR FAST WARMUP CATHODE BACKGROUND OF THE INVENTION This invention relates to heaters for fast warmup cathodes and more particularly to heaters for use in the cathodes of television picture tubes.
In the past many types of fast warmup cathodes have been proposed; however, most have not been commercially acceptable because of high failure rates or prohibitive costs. To accomplish the same result many manufacturers of television receivers have adopted a so-called instant on feature which provides heater current to all of the tubes in the receiver even if it is of While this system is very successful in accomplishing its purpose, it is very wasteful of electrical energy.
To rectify the energy waste, attention has again turned to providing a fast warmup cathode; that is, a cathode which will reach operating temperature and provide a viewable picture on the screen of a cathode ray tube in the neighborhood of5 seconds. Such a cathode has recently been developed and is shown and described in US. patent application Ser. No. 409,041, assigned to the assignee of the present invention, the disclosure of which is herein incorporated by reference.
Such a cathode comprises basically a cup-shaped cap having electron emissive material on the closed end thereof and a cathode stack which is attached to the cap ,by low heat conducting ribbons. This structure works extremely well for its designed purpose but could be improved even further if heat loss could be minimized from the heater encompassed therewithin.
OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of this invention to obviate the disadvantage of the prior art.
It is another object of the invention to enhance heater operation in fast warmup cathodes.
Still another object of the invention is the provision of a heater for a fast warmup cathode which has minimized heat loss.
These objects are accomplished in one aspect of the invention by a heater which comprises an electrically conductive core substantially coveredby an electrically insulating material. The heater is formed to provide a coiled body portion with a pair of extending legs. The height of the coiled body portion is small compared to the legs and to minimize heat loss from the legs the thickness of the insulating material thereon is substantially greater than that of the coiled body portion.
BRIEF DESCRIPTION OF THE DRAWINGS The single FIGURE is a cross-sectional elevational view of a heater constructed in accordance with the invention mounted within a suitable cathode.
DESCRIPTION OF THE PREFERRED EMBODIMENT For a better understanding of the present invention together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above-described drawing.
Referring now to the drawing with greater particularity there is shown a fast warmup cathode 10 comprising a top cap 12 which is substantially cup shaped and includes a closed end 14 having a peripheral'side wall 16 defining a hollow interior 18.
Top cap 12 is supported by a plurality of minimum contact areas 20 formed as part of a hollow cathode sleeve 22.
A heater 24 having an electrically conductive core 26 of a suitable material such as tungsten or molybdenum, surrounded by an electrically insulating coating 28, of a suitable material, such as alumina is positioned within the cathode 10. The heater 24 is formed to provide a coiled body portion 30, which is of small height compared with the height of the heater, which body portion is encompassed within the hollow interior 18 of top cap 12. A pair of legs 32 extend from body 30 through sleeve 22. To minimize heat loss from the extended pair of legs 32 the electrically insulating coating thereon is of much greater thickness than the coating on coiled body portion 30. To be effective the leg coating should be at least 300% and preferably 400% thicker than that on body portion 30. The terminal ends of legs 32 are left bare of insulation so that electrical connection can be made thereto.
In actual tests a heater having a coiled body portion coating thickness of 0.0017 inch and a leg coating thickness of 0.0068 inch showed a 5% improvement in warmup time compared with a heater having a uniform coating of 0.0017 inch. Such a reduction is indeed significant in an area where warmup time reduction is measured in hundredths of a second.
While there have been shown what are the preferred embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of invention as defined by the appended claims.
What is claimed is:
1. A heater for a fast warmup cathode comprising: a metallic, electrically conductive core; and an electrically insulating coating surrounding said core; said heater being formed to provide a coiled body having a pair of legs extending therefrom, the height of said coiled body being small compared with the length of said legs; the insulating coating on said pair of legs having a thickness about 400% greater than the thickness of the insulating coating on the coils of said coiled body portion.
2. The heater of claim 1 wherein said insulating coating is alumina.

Claims (2)

1. A heater for a fast warmup cathode comprising: a metallic, electrically conductive core; and an electrically insulating coating surrounding said core; said heater being formed to provide a coiled body having a pair of legs extending therefrom, the height of said coiled body being small compared with the length of said legs; the insulating coating on said pair of legs having a thickness about 400% greater than the thickness of the insulating coating on the coils of said coiled body portion.
2. The heater of claim 1 wherein said insulating coating is alumina.
US440684A 1974-02-08 1974-02-08 Heater for fast warmup cathode Expired - Lifetime US3883767A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US440684A US3883767A (en) 1974-02-08 1974-02-08 Heater for fast warmup cathode
DE2504673A DE2504673C3 (en) 1974-02-08 1975-02-05 Rapid heating cathode for an electron tube

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Application Number Priority Date Filing Date Title
US440684A US3883767A (en) 1974-02-08 1974-02-08 Heater for fast warmup cathode

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US3883767A true US3883767A (en) 1975-05-13

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DE (1) DE2504673C3 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4000435A (en) * 1975-06-20 1976-12-28 Westinghouse Electric Corporation Electron gun cathode with a fast warm-up characteristic
US4227250A (en) * 1978-11-09 1980-10-07 Bell Telephone Laboratories, Incorporated Minimization of excess bandwidth in pulse amplitude modulated data transmission
US4554479A (en) * 1983-12-08 1985-11-19 Rca Corporation Cathode-ray tube having a low power cathode assembly
US4558254A (en) * 1984-04-30 1985-12-10 Rca Corporation Cathode-ray tube having an improved low power cathode assembly
US6084355A (en) * 1996-12-14 2000-07-04 Samsung Electronics Co., Ltd. Circuit for controlling power supplied to a cathode heater of a cathode ray tube

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2938248A1 (en) * 1979-09-21 1981-03-26 Standard Elektrik Lorenz AG, 70435 Stuttgart HEATING ELEMENT FOR AN INDIRECTLY HEATED CATHODE
DE19828158C1 (en) * 1998-06-24 1999-11-25 Siemens Ag Indirectly heated cathode, especially for X-ray tube

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3056900A (en) * 1960-02-23 1962-10-02 Philco Corp Electrode structures and method of fabricating the same
US3495121A (en) * 1967-04-10 1970-02-10 Siemens Ag Indirectly heated dispenser cathode for electrical discharge vessels
US3553521A (en) * 1967-02-17 1971-01-05 Philips Corp Indirectly heated cathode for an electron discharge tube with an insulated heating element

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3056900A (en) * 1960-02-23 1962-10-02 Philco Corp Electrode structures and method of fabricating the same
US3553521A (en) * 1967-02-17 1971-01-05 Philips Corp Indirectly heated cathode for an electron discharge tube with an insulated heating element
US3495121A (en) * 1967-04-10 1970-02-10 Siemens Ag Indirectly heated dispenser cathode for electrical discharge vessels

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4000435A (en) * 1975-06-20 1976-12-28 Westinghouse Electric Corporation Electron gun cathode with a fast warm-up characteristic
US4227250A (en) * 1978-11-09 1980-10-07 Bell Telephone Laboratories, Incorporated Minimization of excess bandwidth in pulse amplitude modulated data transmission
US4554479A (en) * 1983-12-08 1985-11-19 Rca Corporation Cathode-ray tube having a low power cathode assembly
US4558254A (en) * 1984-04-30 1985-12-10 Rca Corporation Cathode-ray tube having an improved low power cathode assembly
US6084355A (en) * 1996-12-14 2000-07-04 Samsung Electronics Co., Ltd. Circuit for controlling power supplied to a cathode heater of a cathode ray tube

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Publication number Publication date
DE2504673B2 (en) 1978-01-19
DE2504673A1 (en) 1975-08-14
DE2504673C3 (en) 1978-09-21

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AS Assignment

Owner name: NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP.

Free format text: ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATENTS AND APPLICATIONS, SUBJECT TO CONDITIONS AND LICENSES EXISTING AS OF JANUARY 21, 1981.;ASSIGNOR:GTE PRODUCTS CORPORATION A DE CORP.;REEL/FRAME:003992/0284

Effective date: 19810708

Owner name: NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP.,

Free format text: ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATENTS AND APPLICATIONS, SUBJECT TO CONDITIONS AND LICENSES EXISTING AS OF JANUARY 21, 1981.;ASSIGNOR:GTE PRODUCTS CORPORATION A DE CORP.;REEL/FRAME:003992/0284

Effective date: 19810708