US3894858A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preventing thermally induced fracture of cathode ray tube bulbs by application of a thermal insulator
Assignee: Zenith Electronics LLC
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Filing: 1974-01-04
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Granted: 1975-07-15
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Expires: 1994-01-04
Abstract
Abstract Method for reducing the likelihood of cathode ray tube glass bulb and bulb component fracture caused by temperature cycling in the cathode ray tube manufacturing process. Temperature gradients between glass exterior surfaces and glass interior, arising during cooling, are locally reduced. In a preferred embodiment, a thermal insulator is applied prior to cooling, to areas of especially low tensile strength in order to locally reduce the rate of surface cooling and thus locally reduce the coolinginduced surface tensile forces.
Inventors
- 👤 Melvin F Rogers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:24
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/24; H01J9/244; C; C03; C03B; C03B25/00; C03B25/02; H01J29/00; H01J29/86; H01J29/87; Y; Y02; Y02P; Y02P40/00; Y02P40/50; Y02P40/57
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
137 words
IN A TELEVISION CATHODE RAY TUBE MANUFACTURING PROCESS OF EXHAUSTING OR FRIT SELAING A CATHODE RAY TUBE GLASS BULB OF A TYPE COMPRISING A NON-SKIRTED GLASS FRONT PANEL AND A GLASS FUNNEL, OR IN A PROCESS OF ANNEALING OR BAKING OUT SAID FRONT PANEL, WHEREIN IN SAID PROCESS SAID BULB IS HEATED TO TEMPERATURES ABOVE 400*C AND SUBSEQUENTLY COOLED, SAID PROCESS PRODUCING A TEMPERATURE GRADIENT BETWEEN THE FRONT PANEL EXTREME BORDER SURFACE AND MORE REMOTE INNER PORTIONS OF THE FRONT PANEL GLASS WHICH GENERATES CIRCUMFERENTIAL TENSION AT FRONT PANEL EXTREME BORDER, A METHOD FOR REDUCING SAID CIRCUMFERNTIAL TENSION TO LESSEN THE LIKELEHOOD OF FRONT PANEL FRACTURE COMPRISING APPLYING PRIOR TO OR DURING SAID COOLING A THERMAL INSULATOR OVER THE FRONT PANEL EXTREME BORDER SURFACE AND VICINITY SO AS TO LOCALLY REDUCE THE RATE OF GLASS SURFACE COOLING.
Claim 2
Dependent Claim
137 words
IN A TELEVISION CATHODE RAY TUBE MANUFACTURING PROCESS OF EXHAUSTING OR FRIT SELAING A CATHODE RAY TUBE GLASS BULB OF A TYPE COMPRISING A NON-SKIRTED GLASS FRONT PANEL AND A GLASS FUNNEL, OR IN A PROCESS OF ANNEALING OR BAKING OUT SAID FRONT PANEL, WHEREIN IN SAID PROCESS SAID BULB IS HEATED TO TEMPERATURES ABOVE 400*C AND SUBSEQUENTLY COOLED, SAID PROCESS PRODUCING A TEMPERATURE GRADIENT BETWEEN THE FRONT PANEL EXTREME BORDER SURFACE AND MORE REMOTE INNER PORTIONS OF THE FRONT PANEL GLASS WHICH GENERATES CIRCUMFERENTIAL TENSION AT FRONT PANEL EXTREME BORDER, A METHOD FOR REDUCING SAID CIRCUMFERNTIAL TENSION TO LESSEN THE LIKELEHOOD OF FRONT PANEL FRACTURE COMPRISING APPLYING PRIOR TO OR DURING SAID COOLING A THERMAL INSULATOR OVER THE FRONT PANEL EXTREME BORDER SURFACE AND VICINITY SO AS TO LOCALLY REDUCE THE RATE OF GLASS SURFACE COOLING.
Claim 3
Dependent Claim
40 words
A process as defined in claim 1 wherein said application of thermal insulator comprises applying one or more layers of a thermally insulative sheet to said extreme border surface and conforming said layers to said extreme border surface and vicinity.
Claim 4
Dependent Claim
17 words
A process as defined in claim 2 wherein said thermally insulative sheet comprises water moistened asbestos paper.
Claim 5
Dependent Claim
111 words
In a television cathode ray tube manufacturing process of heating a glass front panel having at least one exposed extreme border surface to temperatures above 400*C and subsequently cooling said panel, thus producing a temperature gradient between the front panel extreme border surface and more remote inner portions of the front panel glass which causes tension at the front panel extreme border surface, a method for reducing said tension to thus lessen the likelihood of front panel fracture, said method comprising applying prior to or during said cooling a thermal insulator over the front panel extreme border surface and vicinity so as to locally reduce the rate of glass surface cooling.
Claim 6
Dependent Claim
111 words
In a television cathode ray tube manufacturing process of heating a glass front panel having at least one exposed extreme border surface to temperatures above 400*C and subsequently cooling said panel, thus producing a temperature gradient between the front panel extreme border surface and more remote inner portions of the front panel glass which causes tension at the front panel extreme border surface, a method for reducing said tension to thus lessen the likelihood of front panel fracture, said method comprising applying prior to or during said cooling a thermal insulator over the front panel extreme border surface and vicinity so as to locally reduce the rate of glass surface cooling.
Claim 7
Dependent Claim
45 words
A process as defined in claim 4 wherein said application of thermal insulator comprises applying, prior to or during heating, one or more layers of a thermally insulative sheet to said extreme border surface and conforming said layers to said extreme border surface and vicinity.
Claim 8
Dependent Claim
17 words
A process as defined in claim 5 wherein said thermally insulative sheet comprises water moistened asbestos paper.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-14 | 1979-01-13 | 1979-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-14 | 1983-01-13 | 1983-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-14 | 1987-01-13 | 1987-07-15 | $7700.00 | Window Closed / Lapsed |