Optics: motion pictures – Camera and/or projector drive mechanisms – With speed regulation or selection
Patent
1990-10-26
1992-04-21
Hayes, Monroe H.
Optics: motion pictures
Camera and/or projector drive mechanisms
With speed regulation or selection
352 14, G03B 2148
Patent
active
051061856
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a control and regulating device for film transport in a film projector.
A control device for the film transport in a film projector is known from DE-PS 27 38 322. The known projector has two film reels, one on each side of the film gate and drivable by its own reel motor, two friction roller pairs, driven separately from one another and located between the reels and the gate to produce film loops on both sides of the gate, and a film transport device between the two friction roller pairs for intermittent transport of the film through the gate.
The control device includes one loop-measuring device between each friction roller pair and the gate, and a friction roller pair control circuit which obtains a measurement signal from the loop-measuring device associated with it and delivers an output signal to the drive motor of the associated friction roller pair to maintain a constant film loop size A circuit is also provided which delivers a signal corresponding to the frame frequency, to the film transport device and to the friction roller control circuits to permit operation at a frame frequency settable in advance and variable within a wide range, while maintaining constant film loop sizes on both sides of the gate. In addition, a signal derived from the output signal of the friction roller control circuits is fed to the reel motor control circuits for the reel motors to produce a constant film tension between the friction rollers and the reels.
The control circuits for the drive motors of the supply and takeup devices and for the reel motors as well as the loop sensors are coupled together in such fashion that the film is unwound from the supply reel while maintaining a constant film loop and with an essentially constant tension, and wound on the takeup reel. A precondition for this, however, is that the film be placed in an exactly specified manner in the film channel and positioned on the winding plates so that, as the film is transported in one direction or the other, it will be correctly unwound and wound, and the film will not be damaged or torn because the film reels were incorrectly mounted.
For rapid winding from one reel to the other, the known control device has a fast transport control with dynamic braking that operates only during simple rewinding, while when the film is completely unwound from one of the winding plates, both winding plates are driven again so that the free film end projecting out of the film reel strikes the parts of the film projector arranged at the periphery of the winding plate in question.
An effective runout stop, both during intermittent film transport and during continuous film transport for searching or for fast forward or reverse winding, however, not only increases the ease of operation but is also a requirement for installing remote control and for using a film projector of this kind for film editing.
Since the known control device also has separate drives for the friction roller pairs and separate measuring devices for the film loops formed to the right and left of the film gate, and therefore necessarily has separate friction roller control circuits, it is relatively expensive and moreover cannot be switched, for rapid frame transport, from intermittent film transport to continuous film transport.
The goal of the present invention is to provide a control and regulating device, for film transport in a film projector that permits a direct transition from intermittent frame transport at any possible frame presentation frequency, to continuous fast forward and reverse, and creates the necessary conditions for simply placing the film on the winding plates and permitting an effective runout stop of the film both during intermittent film transport and during fast forward or reverse or in the search mode.
The solution according to the invention makes it possible by providing only one common motor for the supply and takeup devices, to have simplified control and regulation of the film drives both during intermittent film transport according to a giv
REFERENCES:
patent: 3565521 (1971-02-01), Bulter et al.
patent: 4150886 (1979-04-01), Merkel et al.
patent: 4245897 (1981-01-01), Beauviala et al.
patent: 4312576 (1982-01-01), DeJeney
Blaschek Otto
Haas Josef
Popp Thomas
Tschida Ernst
Arnold & Richter Cine Technik GmbH & Co.
Betriebs KG and Arri Cine & Video Gerate Gesellschaft m.b.H.
Hayes Monroe H.
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