US3536527A - Means and method for reducing sparking in cathode ray tubes - Google Patents
Means and method for reducing sparking in cathode ray tubes Download PDFInfo
- 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
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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.
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 |
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US (1) | US3536527A (en) |
Cited By (3)
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)
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 |
-
1967
- 1967-09-11 US US667331A patent/US3536527A/en not_active Expired - Lifetime
Patent Citations (4)
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)
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 |
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