US4094595A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control mechanism for the pull-down pawl of a film projector
Assignee: Robert Bosch GmbH
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Filing: 1977-01-11
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Granted: 1978-06-13
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Expires: 1997-01-11
Abstract
Abstract A control mechanism for the pull-down pawl of a projector, for the projection of films with different frame frequencies, comprises a pot-shaped worm gear and a control drum coaxial with and connected thereto for rotation therewith, movable in axial direction relative thereto and arrestable against a force of biasing means in one of a plurality of selected positions. The control drum is provided on its periphery with a plurality of different cam curves and a pin, movable in a direction normal to the axis of the control drum, engages with one a cam curve, brought in a selected position of the drum in alignment therewith, while the other end of the pin cooperates with a pull-down pawl to move an end of the latter into and out of perforations of the film. The worm gear meshes with a worm driven by a shaft carrying a cam engaged by a cam follower connected to the pull-down pawl to move the latter along a feed stroke when the end of the pull-down pawl is engaged in one of the film perforations.
Inventors
- 👤 Hans Lieckfeldt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:10
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/14; G03B21/32; G03B21/43; G03B21/44; G03B21/48; G03B1/00; G03B1/18; G03B1/20; G03B1/22
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
147 words
In a control mechanism for the pull-down pawl means of a projector for the projection of films with different film frequencies, a combination comprising support means; a drive wheel mounted on said support means for rotation about its axis; a control drum coaxial with said drive wheel and arranged for controlling the movement of one end of the pull-down pawl means into and out of perforations in a film to be projected; a plurality of different cam curves extending axially displaced from each other about the periphery of said control drum; and means connecting said control drum with said drive wheel for rotation with the latter and movable in axial direction relative thereto, said drive wheel being formed with a recess extending in the direction of said axis and dimensioned so that said control drum may be moved in axial direction into and out of said recess.
Claim 2
Dependent Claim
147 words
In a control mechanism for the pull-down pawl means of a projector for the projection of films with different film frequencies, a combination comprising support means; a drive wheel mounted on said support means for rotation about its axis; a control drum coaxial with said drive wheel and arranged for controlling the movement of one end of the pull-down pawl means into and out of perforations in a film to be projected; a plurality of different cam curves extending axially displaced from each other about the periphery of said control drum; and means connecting said control drum with said drive wheel for rotation with the latter and movable in axial direction relative thereto, said drive wheel being formed with a recess extending in the direction of said axis and dimensioned so that said control drum may be moved in axial direction into and out of said recess.
Claim 3
Dependent Claim
74 words
A combination as defined in claim 1, wherein said drive wheel is a worm gear, and including a driven shaft, a worm coaxially fixed to said driven shaft and meshing with said worm gear, and a cam coaxially fixed to said shaft for controlling the stroke of the pull-down pawl means to advance the film while the one end of said pull-down pawl means is located in one of the perforations of the film.
Claim 4
Dependent Claim
26 words
A combination as defined in claim 2, wherein said drive wheel is pot-shaped and having an annular end face defining an open end of said recess.
Claim 5
Dependent Claim
109 words
A combination as defined in claim 3 and including a pin mounted in said support means movable in direction substantially normal to said axis closely adjacent said end face, said pin having one end engaging a selected one of said cam curves, brought in alignment with said pin upon movement of said control drum in axial direction, the other end of said pin engaging said pull-down pawl means to transmit the movement of the pin, imparted thereto by the respective cam curve during rotation of said drum, to said pull-down pawl means to move the one end of the latter into and out of the perforations of the film.
Claim 6
Dependent Claim
68 words
A combination as defined in claim 1, wherein said drive wheel has a central hub extending through a central bore in said control drum, and wherein said means for connecting said drum to said drive wheel comprise a groove provided in the peripheral surface of said hub and extending in the direction of said axis, and a sliding key fixed to said drum and engaged in said groove.
Claim 7
Dependent Claim
49 words
A combination as defined in claim 1, and including biasing means for biasing said drum in a direction out of said recess, and means cooperating with said drum for holding the latter against the force of said biasing means in a predetermined axial position relative to said drive wheel.
Claim 8
Dependent Claim
75 words
A combination as defined in claim 6, wherein said biasing means comprises a compresssion spring arranged in said recess and engaging said drum on one end thereof, and wherein said holding means comprise a lever tiltably mounted at one end on said support means and engaging with the other end thereof said drum on the opposite end of the latter, and means for releasably holding said lever in one of a plurality of tilted positions.
Claim 9
Dependent Claim
59 words
A combination as defined in claim 4, wherein said pull-down pawl means is constituted by a lever having at said one end a detent adapted to engage into perforations of said film and including bearing means on said support means and mounting the other end of said lever tiltable in a plane parallel to said axis and transverse thereto.
Claim 10
Dependent Claim
48 words
A combination as defined in claim 8, wherein said cam on said shaft has an annular cam curve having a generatrix extending normal to said axis and including a cam follower fixed to said lever intermediate the ends thereof and engaging said annular cam curve on said cam.
Claim 11
Dependent Claim
51 words
A combination as defined in claim 9 and including spring means connected at opposite ends to said lever and said support means for maintaining said cam follower in engagement with said annular cam curve and said one end of said pin in engagement with a selected cam curve on said drum.
Claim 12
Dependent Claim
53 words
A combination as defined in claim 10, and including an objective, a film guide adjacent one end of said objective, a rotatable shutter between said film guide and said one end of said objective, a shutter shaft carrying said shutter for rotation, and transmission means between said driven shaft and said shutter shaft.
Claim 13
Dependent Claim
34 words
A combination as defined in claim 11, wherein said shutter shaft extends parallel to said driven shaft, and wherein said transmission means comprise a belt drive between said driven shaft and said shutter shaft.
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) | 1981-06-12 | 1981-12-12 | 1982-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-12 | 1985-12-12 | 1986-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-12 | 1989-12-12 | 1990-06-13 | $7700.00 | Window Closed / Lapsed |