Electronic watch

摘要

Provided is an electronic watch capable of, even if an indicating hand having a large moment of inertia is used, accurately determining success and failure of rotation. The electronic watch detects rotation by using a first detection mode determination circuit (12) and a second detection mode determination circuit (13). In the electronic watch, a timing counter (14) for measuring a time after an output of a normal drive pulse is followed by a detection pulse selection circuit (151) provided as changing means for changing a width or a frequency of a detection pulse in accordance with an output time of the detection pulse. The detection pulse detects the rotation and simultaneously serves as an electromagnetic brake for a rotor (10). The electromagnetic brake for the rotor (10) is controlled by changing the width or the frequency of the detection pulse in a predetermined period, thereby achieving an accurate rotation detection. Alternatively, the setting of the width or the frequency of the detection pulse may be changed in accordance with a determination result in a first detection mode, an output voltage of a power supply, and a driving power of the normal drive pulse, instead of the output timing of the detection pulse.

主权项

1. An electronic watch, comprising:
a stepper motor including a rotor and a coil; a motor driver for driving the stepper motor; a reference signal generation circuit for outputting various kinds of timing signals; a pulse shaping circuit for generating various kinds of pulse signals for driving the stepper motor, in response to the various kinds of timing signals output from the reference signal generation circuit; a pulse selection circuit for selecting various kinds of pulses supplied from the pulse shaping circuit and outputting the selected pulses to the motor driver; and a rotation detection circuit for detecting whether the rotor has rotated or not based on counter-electromotive force resulting from free oscillation of the rotor, the pulse shaping circuit comprising:
a normal drive pulse generation circuit for outputting a normal drive pulse at a time of driving the stepper motor;a detection pulse generation circuit for outputting, at a predetermined time after the normal drive pulse is output, a detection pulse for causing the rotation detection circuit to perform rotation detection; anda correction drive pulse generation circuit for outputting a correction drive pulse when the rotation detection circuit detects that the rotor has not rotated, wherein the electronic watch further comprises a detection pulse change factor detector configured to detect a factor of changing a pulse width of the detection pulse, and output a detection signal, wherein the detection pulse generation circuit is capable of changing the pulse width of the detection pulse, and wherein the detection pulse generation circuit changes the pulse width of the detection pulse to be output, in accordance with the detection signal of the detection pulse change factor detector.