US3536527A - Means and method for reducing sparking in cathode ray tubes - Google Patents

Means and method for reducing sparking in cathode ray tubes Download PDF

Info

Publication number
US3536527A
US3536527A US667331A US3536527DA US3536527A US 3536527 A US3536527 A US 3536527A US 667331 A US667331 A US 667331A US 3536527D A US3536527D A US 3536527DA US 3536527 A US3536527 A US 3536527A
Authority
US
United States
Prior art keywords
cathode ray
coating
ray tubes
sparking
reducing sparking
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
US667331A
Inventor
Laszlo Javorik
Otto Laudi
Robert A Mitchell
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.)
National Video Corp
Original Assignee
National Video 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
Application filed by National Video Corp filed Critical National Video Corp
Application granted granted Critical
Publication of US3536527A publication Critical patent/US3536527A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • 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
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/88—Vessels; Containers; Vacuum locks provided with coatings on the walls thereof; Selection of materials for the coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
    • H01J5/02—Vessels; Containers; Shields associated therewith; Vacuum locks
    • H01J5/08—Vessels; Containers; Shields associated therewith; Vacuum locks provided with coatings on the walls thereof; Selection of materials for the coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/88—Coatings
    • H01J2229/882—Coatings having particular electrical resistive or conductive properties

Definitions

  • Cathode ray tubes conventionally have an interior coating of an electrically conductive carbonaceous material.
  • an electrically conductive carbonaceous material Commonly used for this purpose is a product known as Aquadag and commonly referred to throughout the television industry as dag.
  • the carbonaceous layer extends from near the edge of the funnel portion of the tube back into the gun portion and serves as a means for conducting electric current to apply a potential of the order of 25 kv. to the electron gun.
  • particles of the dag become detached from the coating and result in interior sparking or arcing and consequently, a poor television picture.
  • a supplemental coating particularly one compatible with the usual dag coating, this problem can be resolved.
  • a coating made up of aluminum hydroxide and a soluble silicate is particularly advantageous for this purpose.
  • EXAMPLE For the purpose of preparing the anti-sparking coating material, we use one part by weight of deionized Water with one part by Weight of purified gelatinous aluminum hydroxide. This mixture is placed within a ball mill using porcelain balls and milled for 24 hours at room temperature (6878 F.). Thereafter the suspension so achieved was mixed by taking 25 parts by volume of the aluminum hydroxide suspension and mixed with 75 parts by volume of potassium silicate solution (electronic grade),
  • a cathode ray tube having an enlarged portion at one end providing a front viewing screen and a reduced portion at the other end housing an electron gun, said tube having an interior electrically conductive carbonaceous coating extending rearwardly from said screen, the improved supplemental coating interiorly of and on said carbonaceous coating and consisting essentially of about 25 parts by volume of aluminum hydroxide and about parts by volume of potassium silicate.

Landscapes

  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)

Description

3,536,527 MEANS AND METHOD FOR REDUCING SPARK- IING 1N CATHODE RAY TUBES Laszlo .lavorik and (Mo Landi, Chicago, and Robert A.
Mitchell, Berwyn, 111., assignors to National Video Corporation, Chicago, 111., a corporation of Illinois No Drawing. Filed Sept. 11, 1967, Ser. No. 667,331 Int. Cl. 344d 1/02 US. Cl. 117-216 2 Claims ABSTRACT OF THE DHSCLOSURE An anti-sparking coating for the interior of a cathode ray tube which is applied over the usual electrically con ductive carbonaceous coating, the supplemental coating consisting essentially of aluminum hydroxide and a soluble silicate.
SUMMARY OF THE INVENTION Cathode ray tubes conventionally have an interior coating of an electrically conductive carbonaceous material. Commonly used for this purpose is a product known as Aquadag and commonly referred to throughout the television industry as dag. The carbonaceous layer extends from near the edge of the funnel portion of the tube back into the gun portion and serves as a means for conducting electric current to apply a potential of the order of 25 kv. to the electron gun. Frequently during the life of such a tube, particles of the dag become detached from the coating and result in interior sparking or arcing and consequently, a poor television picture. We have found that through the use of a supplemental coating, particularly one compatible with the usual dag coating, this problem can be resolved. We find that a coating made up of aluminum hydroxide and a soluble silicate is particularly advantageous for this purpose. A specific example of the practice of the invention is set forth below.
EXAMPLE For the purpose of preparing the anti-sparking coating material, we use one part by weight of deionized Water with one part by Weight of purified gelatinous aluminum hydroxide. This mixture is placed within a ball mill using porcelain balls and milled for 24 hours at room temperature (6878 F.). Thereafter the suspension so achieved was mixed by taking 25 parts by volume of the aluminum hydroxide suspension and mixed with 75 parts by volume of potassium silicate solution (electronic grade),
the potassium silicate solution having a specific gravity I of 1.26. This mixture was agitated for one hour and thereafter sprayed thoroughly and evenly over the inner dag surface (which was previously baked to its final condition) using airless spray apparatus. The supplemental coating was then baked dry in conventional fashion.
With the foregoing coating, We find that if there is any tendency of the multiple-coating to flake, it occurs in the aluminum oxide which Will not cause sparking.
While in the foregoing specification a detailed description of an embodiment of the invention has been set down for the purpose of illustration, many variations in the details herein given may be made by those skilled in the art Without departing from the spirit and scope of the invention.
We claim:
1. In a cathode ray tube having an enlarged portion at one end providing a front viewing screen and a reduced portion at the other end housing an electron gun, said tube having an interior electrically conductive carbonaceous coating extending rearwardly from said screen, the improved supplemental coating interiorly of and on said carbonaceous coating and consisting essentially of about 25 parts by volume of aluminum hydroxide and about parts by volume of potassium silicate.
2. In a method for suppressing sparking in cathode ray tubes having an electrically conductive carbonaceous layer on the tube interior extending rearwardly from the front viewing screen, the steps of spraying over said layer an aqueous mixture consisting essentially of about 25 parts by volume of aluminum hydroxide and about 75 parts by volume of potassium silicate, the said potassium silicate having a specific gravity of about 1.26, and thereafter drying the sprayed mixture.
References Cited UNITED STATES PATENTS 2,223,924 12/1940 Stephan 313-64 X 2,496,901 2/1950 Van Hoorn.
2,951,773 9/1960 Helle et al. 117-226 X 3,108,906 10/ 1963 Scharrer et a1 117-226 ALFRED L. LEAVITT, Primary Examiner C. K. WEIFFENBACH, Assistant Examiner US. Cl. X.R.
US667331A 1967-09-11 1967-09-11 Means and method for reducing sparking in cathode ray tubes Expired - Lifetime US3536527A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US66733167A 1967-09-11 1967-09-11

Publications (1)

Publication Number Publication Date
US3536527A true US3536527A (en) 1970-10-27

Family

ID=24677793

Family Applications (1)

Application Number Title Priority Date Filing Date
US667331A Expired - Lifetime US3536527A (en) 1967-09-11 1967-09-11 Means and method for reducing sparking in cathode ray tubes

Country Status (1)

Country Link
US (1) US3536527A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3791846A (en) * 1972-02-02 1974-02-12 Zenith Radio Corp Method for applying an internal coating to a cathode ray tube
US3979632A (en) * 1974-07-17 1976-09-07 Gte Sylvania Incorporated Cathode ray tube having surface charge inhibiting means therein
US4210844A (en) * 1978-11-20 1980-07-01 Gte Sylvania Incorporated Cathode ray tube arc suppressor coating

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2223924A (en) * 1936-11-20 1940-12-03 Firm J D Riedel E De Haen Akt Preparation for use in carbon coating television tubes
US2496901A (en) * 1943-07-06 1950-02-07 Hartford Nat Bank & Trust Co Method and composition for coating cathode-ray tubes
US2951773A (en) * 1955-02-12 1960-09-06 Philips Corp Method of coating electrical discharge tubes
US3108906A (en) * 1958-05-24 1963-10-29 Philips Corp Electric discharge tube

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2223924A (en) * 1936-11-20 1940-12-03 Firm J D Riedel E De Haen Akt Preparation for use in carbon coating television tubes
US2496901A (en) * 1943-07-06 1950-02-07 Hartford Nat Bank & Trust Co Method and composition for coating cathode-ray tubes
US2951773A (en) * 1955-02-12 1960-09-06 Philips Corp Method of coating electrical discharge tubes
US3108906A (en) * 1958-05-24 1963-10-29 Philips Corp Electric discharge tube

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3791846A (en) * 1972-02-02 1974-02-12 Zenith Radio Corp Method for applying an internal coating to a cathode ray tube
US3979632A (en) * 1974-07-17 1976-09-07 Gte Sylvania Incorporated Cathode ray tube having surface charge inhibiting means therein
US4210844A (en) * 1978-11-20 1980-07-01 Gte Sylvania Incorporated Cathode ray tube arc suppressor coating

Similar Documents

Publication Publication Date Title
US3355617A (en) Reduction of arcing between electrodes in a cathode ray tube by conducting coating of resistance material on inner wall of tube neck
US3791546A (en) Cathode-ray tube having conductive internal coating comprised of iron oxide and graphite
GB651061A (en) Improvements in and relating to electron discharge devices
US2586304A (en) Protection of phosphors from attack by alkali vapors
US4092444A (en) Cathode ray tube having amorphous resistive film on internal surfaces and method of forming the film
US3536527A (en) Means and method for reducing sparking in cathode ray tubes
US2264858A (en) Electrical discharge device
US4124540A (en) Resistive electrical conductive coating for use in a cathode ray tube
US2508001A (en) High-voltage cathode-ray tube corona ring
US3108906A (en) Electric discharge tube
US5300856A (en) Resistive, adhesive-primer coating for a display apparatus and method of making same
US3532640A (en) Graphite suspension for the conducting inner layer of cathode ray tubes
US4528477A (en) CRT with optical window
US4249107A (en) Cathode ray tube having amorphous resistive film on internal surfaces and method of forming the film
US2496901A (en) Method and composition for coating cathode-ray tubes
US2171230A (en) Insulating coating
US4638213A (en) CRT with internal contact stripe or patch and method of making said stripe or patch
US2751515A (en) Cathode-ray tube
US2836751A (en) Cathode ray tube manufacture
JPS6120990B2 (en)
US4280931A (en) Method and composition for electrically resistive material for television cathode ray tubes
US2887595A (en) Television camera tube
US4260930A (en) Cathode ray tube getter having two arms connected to final electrode by insulating connector
US4681775A (en) CRT with optical window and method
US4076354A (en) Method for conditioning an edge of an internal electric conductive film of a cathode ray tube