Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
201 words
The method of continuously driving a perforated strip of film in a manner calculated to avoid damaging its perforations, the strip of film being characterized by a maximum safe driving tension, said method comprising the steps of: selecting a toothed drive sprocket having circumferential teeth adapted to engage the corresponding perforations in the strip of film; engaging the sprocket teeth with the film perforations; selecting a magnetically controlled clutch having two relatively rotatable plates and also having circuit means energizable for establishing a selected degree of mechanical coupling between the plates; selecting an alternating voltage source, rectifying the voltage from the source, and then applying the rectified voltage to the circuit means; fixedly securing one clutch plate to the drive sprocket; energizing the circuit means at a level sufficient to couple the clutch plates with an amount of torque sufficient to drive the strip of film but not sufficient to produce the maximum safe driving tension in the strip of film; and then rotatably driving the other clutch plate so as to advance the strip of film; whereby if the film tension unexpectedly increases, the clutch plates will slip relative to each other before the maximum safe driving tension is exceeded.
Claim 2
Independent Claim
201 words
The method of continuously driving a perforated strip of film in a manner calculated to avoid damaging its perforations, the strip of film being characterized by a maximum safe driving tension, said method comprising the steps of: selecting a toothed drive sprocket having circumferential teeth adapted to engage the corresponding perforations in the strip of film; engaging the sprocket teeth with the film perforations; selecting a magnetically controlled clutch having two relatively rotatable plates and also having circuit means energizable for establishing a selected degree of mechanical coupling between the plates; selecting an alternating voltage source, rectifying the voltage from the source, and then applying the rectified voltage to the circuit means; fixedly securing one clutch plate to the drive sprocket; energizing the circuit means at a level sufficient to couple the clutch plates with an amount of torque sufficient to drive the strip of film but not sufficient to produce the maximum safe driving tension in the strip of film; and then rotatably driving the other clutch plate so as to advance the strip of film; whereby if the film tension unexpectedly increases, the clutch plates will slip relative to each other before the maximum safe driving tension is exceeded.
Claim 3
Dependent Claim
29 words
The method of claim 1 which includes the additional steps of sensing the film movement, and discontinuing the rotational drive of the other clutch plate when film movement stops.
Claim 4
Dependent Claim
34 words
The method of claim 1 which includes the additional steps of sensing the film tension, and discontinuing the rotational drive of the other clutch plate when film tension falls outside of predetermined acceptable limits.
Claim 5
Independent Claim
153 words
The method of selectively driving and selectively stopping a strip of film in a film printing machine, comprising the steps of: selecting a drive sprocket having a circumferential row of teeth; threading the strip of film upon the sprocket and engaging the sprocket teeth with the film perforations; securing one plate of a friction clutch to the drive sprocket to rotate therewith; selecting a drive motor; coupling a second clutch plate of the friction clutch to the motor to rotate therewith; coupling a fly wheel to the motor to rotate therewith, so as to maintain uniform film speed when the film is moving; energizing the motor, and bringing the two clutch plates into engagement so as to drivingly advance the film; and when the film is to be stopped, bringing the clutch plates out of engagement so that the film will stop its movement while the motor and fly wheel are still rotating.
Claim 6
Independent Claim
153 words
The method of selectively driving and selectively stopping a strip of film in a film printing machine, comprising the steps of: selecting a drive sprocket having a circumferential row of teeth; threading the strip of film upon the sprocket and engaging the sprocket teeth with the film perforations; securing one plate of a friction clutch to the drive sprocket to rotate therewith; selecting a drive motor; coupling a second clutch plate of the friction clutch to the motor to rotate therewith; coupling a fly wheel to the motor to rotate therewith, so as to maintain uniform film speed when the film is moving; energizing the motor, and bringing the two clutch plates into engagement so as to drivingly advance the film; and when the film is to be stopped, bringing the clutch plates out of engagement so that the film will stop its movement while the motor and fly wheel are still rotating.