US4090389A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of drawing a shadow mask
Assignee: US Philips Corp
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Filing: 1976-06-17
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Granted: 1978-05-23
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Expires: 1996-06-17
Abstract
Abstract A method of drape drawing a shadow mask from a foraminous, or apertured, metal sheet that has a greater tensile in one direction than another and has edges extending in the one direction. During the drape procedure, the edges of the sheet that extend substantially in the direction in which the sheet has the greater tensile strength are allowed to slip relative to the draw ring and the pressure. As a result of this, the sheet is prevented from tearing.
Inventors
- 👤 Adrianus J. VAN Denderen
- 👤 Marianus A. G. VAN DE Kerkhof
- 👤 Mathias A. C. Peters
- 👤 Jan VAN DER Waal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:31
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/14; H01J9/142
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
116 words
A method of drape drawing a shadow mask for a color cathode ray tube from a metal sheet which has a large number of apertures and a greater tensile strength in one direction than another, said method comprising the steps of: clamping edge portions of said sheet; drawing the central portion of said sheet over a draw die; and allowing selected edge portions that extend substantially in said one direction to slip in said other direction in response to tensile force exerted on said sheet by said drawing while holding other selected edge portions that extend in said other direction fixedly clamped; and subsequently bending the edge portions over to form an edge of said mask.
Claim 2
Independent Claim
116 words
A method of drape drawing a shadow mask for a color cathode ray tube from a metal sheet which has a large number of apertures and a greater tensile strength in one direction than another, said method comprising the steps of: clamping edge portions of said sheet; drawing the central portion of said sheet over a draw die; and allowing selected edge portions that extend substantially in said one direction to slip in said other direction in response to tensile force exerted on said sheet by said drawing while holding other selected edge portions that extend in said other direction fixedly clamped; and subsequently bending the edge portions over to form an edge of said mask.
Claim 3
Dependent Claim
39 words
A method according to claim 1 in which said drawing is completed by deforming the central portion of said sheet in contact with the surface of said draw die, and said other direction is perpendicular to said one direction.
Claim 4
Dependent Claim
109 words
A method according to claim 1 in which said central portion of said sheet has a generally rectangular outline with two short sides extending in said one direction and two long sides that extend in said other direction, said apertures being arranged so that the tensile strength of said sheet is greater in the direction parallel to said short sides than in the direction parallel to said long sides, and said edge portions that are allowed to slip are said short sides, said step of drawing said sheet causing deformation of the central portion of said sheet convexly with respect both to said long sides and said short sides.
Claim 5
Dependent Claim
58 words
A method according to claim 3 in which said apertures are alongated substantially parallel to said short sides, and are oriented end to end in rows and have relatively narrow bridges between proximal ends as compared with the portions of said sheet between adjacent rows of said apertures, said drawing being only in the direction of said rows.
References Cited (Backward Citations)
US2514005A
Cited
US3668914A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-05-22 | 1981-11-21 | 1982-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-22 | 1985-11-21 | 1986-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-22 | 1989-11-21 | 1990-05-23 | $7700.00 | Window Closed / Lapsed |