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US 4,057,333 AGranted
Exposure time control device in a cinecamera
AssigneeNippon Kogaku K.K.
InventorsShigeo Akasaka, Hiroaki Tanaka
Life of this patent
Estimating the term…
Abstract
An exposure time control device in a cinecamera comprises a rotatable shutter, an electric motor for driving the shutter, a power source for the motor, and changing means operatively associated with the rotatable shutter to change the number of revolutions of the motor within a period during which an aperture is opened and closed by the rotatable shutter.
Claims9
An exposure time control device for a cinecamera comprising:
- a. rotatable shutter means;
- b. means including an electric motor for driving said rotatable shutter means;
- c. changing means operatively associated with said rotatable shutter means to change the number of revolutions of said electric motor within a period during which an aperture is opened and closed by said rotatable shutter means;
- and
- d. circuit means for supplying an electrical signal to said motor for energization thereof, and wherein said changing means includes means to change the magnitude of said electrical signal within a period during which an aperture is opened and closed by said rotatable shutter means thereby to change the number of revolutions of said motor according to said magnitude.
2 more elements
An exposure time control device for a cinecamera comprising:
- a. rotatable shutter means;
- b. means including an electric motor for driving said rotatable shutter means;
- c. changing means operatively associated with said rotatable shutter means to change the number of revolutions of said electric motor within a period during which an aperture is opened and closed by said rotatable shutter means;
- and
- d. power source means for supplying a current to said motor, and wherein said changing means for changing the number of revolutions of said motor includes means for controlling the motor current which is supplied from said power source means to said motor, and change-over switch means operatively associated with said rotatable shutter means to operate said current control means in at least two-state conditions.
2 more elements
An exposure time control device for a cinecamera comprising:
- a. rotatable shutter means;
- b. means including an electric motor for drivng said rotatable shutter means;
- c. changing means operatively associated with said rotatable shutter means to change the number of revolutions of said electric motor within a period during which an aperture is opened and closed by said rotatable shutter means;
- and
- d. a negative feedback circuit for maintaining a stable number of revolutions of said electric motor, said negative feedback circuit comprising:
- means for detecting a variation in the number of revolutions of said electric motor;
- control means for controlling the current flowing to said electric motor;
- and
- actuation means for actuating said control means so that the motor current may suppress the variation in the number of revolutions of said motor in accordance with the output of said detector means;
- said changing means for changing the number of revolutions being operatively associated with said rotatable shutter means to vary the output of said actuator means independently of said detector means.
7 more elements
Dependencies are inferred from the claim text.