| 摘要 |
A magnetic recording device of a camera is driven, while a photographic film is advanced by one frame by a motor, to record photographic data on a magnetic recording layer of the film. A current flowing through the motor contains a periodically changing ripple signal. The ripple signal detected by a ripple detector is converted into ripple pulses by a wave-shaping circuit. The ripple pulses are supplied to a prescaler which generates one prescaler pulse each time a predetermined number of ripple pulses are counted. A timing signal is generated at the period obtained by multiplying the prescaler pulse period by a coefficient K. One bit data is read in response to the timing signal and recorded on the photographic film. The coefficient K is calculated each time one frame advance is completed, and is used for the next frame data record. In a preferred embodiment, a rotary member is fixed to the rotary shaft of the motor. A photosensor detects the rotation of the rotary member and generates pulses to be supplied to the prescaler.
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