| 摘要 |
PURPOSE:To enable the exact time display after the removal of a strong magnetic field even if a wrist watch is exposed to the strong magnetic field by stopping a step motor upon detection of an external magnetic field and driving the step motor to make fast feed when the external magnetic field is removed in accordance with the memory content during the stop period. CONSTITUTION:A switch 7 is turned off by a chattering prevention circuit 8 when a magnetic sensor 9 detects the prescribed intensity or above of the external magnetic field. The step motor 11 is stopped regardless of the on and off states of a switch 6 which attains the on state to supply a fast feed pulse S2 to a motor driving circuit 10 so as to drive the motor 11 by responding to the dissidence output of a coincidence circuit 4. The switch 6 turns on and the motor 11 is fast fed until the count value during the stop period by a counter 3 till the removal of the external magnetic field and the count value of the pulse S2 by a fast feed counter 5 coincide with each other after the removal of said external magnetic field. The time displayed on a display device 12 is then corrected. The exact time display after the removal of the strong magnetic field is thus executed even if the wrist watch is exposed to the strong magnetic field.
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