US 4,400,074 A · Automatic rewinding camera

Abstract

An automatic rewinding camera wherein an automatic advance of the photographic film by one frame is caused by shutter release operation and rewinding of the photographic film is automatically started when the film is prevented from further advance. The camera has a film-driven sprocket wheel, by the rotation of which film movement signals are produced. A timer circuit maintains, during the passage of a predetermined active time which is shorter than the time required to advance the photographic film by one frame, the camera motor in forward rotation so as to advance the photographic film. The timer circuit is reset by the film movement signals. But when those film signals stop, that is, when the film is fully extended from the cartridge, then the timer is not reset; and the measurement of the full predetermined active time, by the timer, without resetting, results in the motor being reversed to rewind the film.

Claims25

Dependent claims

In a camera having a shutter and reversible motor for advancing and rewinding a photographic film and control means for controlling the motor to rotate in forward and reverse directions, and means automatically to actuate the motor to advance the photographic film one frame after each actuation of the shutter and to rewind the film after all the film has been exposed;

the improvement comprising:
rotatable means which is driven by movement of said photographic film;
signal producing means responsive to rotation of said rotatable means for producing first signals;
timer means for measuring a predetermined active time shorter than the time required to advance said photographic film one frame, said timer means measuring also a predetermined active time longer than the time required to advance said photographic film one frame and permitting the motor to rotate in the forward direction when the camera is not loaded with film, for purposes of demonstrating the camera;
reset means for resetting said timer means when said reset means receives a said first signal;
and
means to reverse the motor to rewind the film when said timer means completes the measurement of said predetermined active time.

4 more elements

A camera comprising:

a reversible motor for advancing a photographic film in forward rotation and rewinding the film in reverse rotation;
control means for selectively establishing a circuit energizing said motor in forward rotation, a circuit reversing said motor, and a short circuit;
a sprocket wheel driven by movement of said photograhic film;
signal producing means for producing first signals during rotation of said sprocket wheel;
a shutter for exposing sid photographic film;
shutter cocking means operative upon movement of said film;
a release lever for tripping said shutter;
a film advancing switch which is automatically turned on after the shutter is tripped and turned off after said photographic film is advanced one frame;
first timer means operative while said film advancing switch is turned on for measuring an active time shorter than the time required to advance said photographic film one frame, during which active time said control means establishes said motor energizing circuit to energize the motor in forward rotation;
reset means for resetting said timer means when said reset means receives a said first signal;
and
reversing control means which is operative while said film advancing switch is turned on to cause said control means to establish said motor energizing circuit to energize the motor in reverse rotation after the lapse of said active time, said motor energizing circuit being maintained in the latter condition until said film advancing switch is turned off after the completion of film rewinding.

9 more elements

A camera comprising:

a reversible motor for advancing a photographic film in forward rotation and rewinding the film in reverse rotation;
first electrical relay means for allowing said motor to rotate in said forward direction;
second electrical relay means for allowing said motor to be reversed;
a shutter for allowing said photographic film to be exposed, said shutter being cocked during the advance of said photographic film by one frame;
a film advancing switch which is turned on after said advance of said photographic film by one frame and turned off after said shutter is tripped;
first timer means which is operative while said film advancing switch is turned on and said second relay means is deenergized so as to maintain said first relay means energized during the elapse of an active time measured by said first timer means, said active time being shorter than the time required to advance said photographic film one frame;
second timer means which is operative while said film advancing switch is turned on and said first means is deenergized so as to energize said second relay means after the elapse of an active time measured by said second timer means;
third timer means which is caused to be operative when said second relay means is energized so as to maintain said second relay means energized during the elapse of an active time thereof longer than the time to advance said photographic film one frame;
a sprocket wheel which is driven by movement of said photographic film;
signal producing means for producing first signals during rotation of said sprocket wheel;
and
reset means for resetting said first and third timer means so as to measure each its respective active time when said reset means receives a said first signal.

9 more elements

Dependencies are inferred from the claim text.

Automatic rewinding camera

Life of this patent

Automatic rewinding camera

Life of this patent

Abstract

Claims25