US3817611A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Run-out and safety switch mechanism for motion picture projectors
Assignee: FG Group Holdings Inc
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Filing: 1973-03-09
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Granted: 1974-06-18
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Expires: 1993-03-09
Abstract
Abstract A run-out and safety switch mechanism positioned between the lower sprocket and the take-up reel of a motion picture projector including two, spaced-apart sensing arms held by spring tension in sliding engagement with the opposing edges of the film strip. A limit switch positioned between the two sensing arms is actuated whenever the absence of any portion of the film strip being transported permits the spacing between the two sensing arms to decrease below a predetermined limit. The body of the limit switch is mounted on the inside of one of the two sensing arms and is actuated by the approach of the other sensing arm. Retaining buttons at the extremity of each sensing arm hold the film strip in a captured position even during start-up when excessive loop lengths may form between the lower sprocket and the take-up reel.
Inventors
- 👤 I Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:48
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/14; G03B21/32; G03B21/43
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
129 words
In a motion picture projector, the combination comprising: sprocket and guide means for advancing a filmstrip from a supply reel to a take-up reel, first and second spaced-apart swing arms mounted for pivotal motion about first and second axes respectively, said axes being spaced apart by distance approximately equal to the width of said filmstrip, spring means urging the extended ends of said swing arms toward one another and into sliding eNgagement with the outer edges of said advancing filmstrip, and electrical switching means mounted on one of said arms for actuation by the approach of the other of said arms to deenergize said sprocket and guide means whenever the absence of any portion of said filmstrip allows the spacing between said arms to decrease below a predetermined limit.
Claim 2
Dependent Claim
129 words
In a motion picture projector, the combination comprising: sprocket and guide means for advancing a filmstrip from a supply reel to a take-up reel, first and second spaced-apart swing arms mounted for pivotal motion about first and second axes respectively, said axes being spaced apart by distance approximately equal to the width of said filmstrip, spring means urging the extended ends of said swing arms toward one another and into sliding eNgagement with the outer edges of said advancing filmstrip, and electrical switching means mounted on one of said arms for actuation by the approach of the other of said arms to deenergize said sprocket and guide means whenever the absence of any portion of said filmstrip allows the spacing between said arms to decrease below a predetermined limit.
Claim 3
Dependent Claim
52 words
The combination as set forth in claim 1 wherein each of said swing arms extends beyond the normal position of said filmstrip and wherein said arms are provided at their extremities with opposing retaining members which extend toward one another whereby said filmstrip is retained in a captured position between said arms.
Claim 4
Dependent Claim
171 words
A protected motion picture filmstrip transport mechanism comprising, in combination: a supply reel having a length of motion picture filmstrip wound thereon, a series of motor-driven sprockets for transporting said filmstrip, a take-up reel for receiving saidfilmstrip from said sprockets, and a safety switch for shutting down the operation of said motor-driven sprockets in response to the breaking or splitting of said filmstrip, said safety switch comprising, incombination: first and second spaced-apart swing arms mounted for pivotal motion about first and second axes respectively, said axes being spaced apart by distance approximately equal to the width of said filmstrip, spring means urging the extended ends of said swing arms toward one another and into sliding engagement with the outer edges of said advancing filmstrip, and electrical switching means mounted on one of said arms for actuation by the approach of the other of said arms to de-energize said motor-driven sprockets whenever the absence of any portion of said filmstrip allows the spacing between said arms to decrease below a predetermined limit.
Claim 5
Dependent Claim
171 words
A protected motion picture filmstrip transport mechanism comprising, in combination: a supply reel having a length of motion picture filmstrip wound thereon, a series of motor-driven sprockets for transporting said filmstrip, a take-up reel for receiving saidfilmstrip from said sprockets, and a safety switch for shutting down the operation of said motor-driven sprockets in response to the breaking or splitting of said filmstrip, said safety switch comprising, incombination: first and second spaced-apart swing arms mounted for pivotal motion about first and second axes respectively, said axes being spaced apart by distance approximately equal to the width of said filmstrip, spring means urging the extended ends of said swing arms toward one another and into sliding engagement with the outer edges of said advancing filmstrip, and electrical switching means mounted on one of said arms for actuation by the approach of the other of said arms to de-energize said motor-driven sprockets whenever the absence of any portion of said filmstrip allows the spacing between said arms to decrease below a predetermined limit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-17 | 1977-12-17 | 1978-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-17 | 1981-12-17 | 1982-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-17 | 1985-12-17 | 1986-06-18 | $7700.00 | Window Closed / Lapsed |