Citizen Watch Company, Ltd.

Daisuke Iri

Toshiaki Fukushima

Yu Takyoh

Toshinari Maeda

Daisuke Matsuoh

Yu Takyo

Masatoshi Nishida

Shogo Sezaki

An electronic watch with a two-coil stepper motor including: a magnetized rotor; a stator including: first and second stator magnetic-pole portions, which are formed so as to oppose to each other through the rotor; and a third stator magnetic-pole portion, which is formed between the first stator magnetic-pole portion and the second stator magnetic-pole portion so as to face the rotor; a coil A to be magnetically coupled to the first stator magnetic-pole portion and the third stator magnetic-pole portion; and a coil B to be magnetically coupled to the second stator magnetic-pole portion and the third stator magnetic-pole portion; and a high-speed drive pulse generation circuit configured to output a drive pulse for driving the rotor to the coil A or the coil B, and wherein the rotor is rotationally driven in increments of 360&#xb0; due to a drive pulse train formed of the plurality of drive pulses.

Step motor drive device and circuit

Provided is a drive circuit for a two-coil stepper motor, including: a rotor; a stator including first, second, and third stator magnetic-pole portions; a coil A to be magnetically coupled to the first stator magnetic-pole portion and the third stator magnetic-pole portion; a coil B to be magnetically coupled to the second stator magnetic-pole portion and the third stator magnetic-pole portion; a drive pulse generation circuit configured to output a drive pulse; a detection pulse generation circuit configured to output a detection pulse for detecting counter-electromotive currents generated in the coil A and the coil B; and a rotation detection circuit configured to receive a detection signal generated due to the detection pulse as input to determine whether or not the rotor has rotated.

Drive circuit for two-coil step motor

Electronic watch

Drive circuit for two-coil step motor, two-coil step motor, and electronic watch using these

An electronic watch includes: a step motor; a driving pulse generator circuit configured to output a driving pulse for driving the step motor; a detection pulse generator circuit configured to output a detection pulse for detecting rotation of the step motor; a correction pulse generator circuit configured to output a correction pulse; a pulse selection circuit configured to select and output the driving pulse, the detection pulse, and the correction pulse; a driver circuit configured to supply to the step motor the outputs from the pulse selection circuit; and a rotation detection circuit configured to receive a detection signal generated by the detection pulse to judge rotation of the step motor. The electronic watch further includes a driving interval switch circuit configured to switch a driving interval of the driving pulse between a normal driving interval and a high-speed driving interval. The rotation detection circuit is capable of changing a detection condition by the driving interval switch circuit.

Provided is an electronic watch which achieves a highest-speed fast-forward operation of a step motor based on various environments under which the watch is placed, and enables low-power driving. The electronic watch includes: a normal pulse generator circuit configured to output a normal pulse SP for driving a step motor; a detection pulse generator circuit configured to output, after the step motor has been driven with the normal pulse SP, detection pulses DPand DPfor detecting whether or not the step motor has been rotated; a pulse selection circuit configured to selectively output the normal pulse SP and the detection pulses DPand DP; a rotation detector circuit configured to input detection signals DSand DSgenerated from the detection pulses DPand DP, and to determine whether or not the step motor has been rotated; and a frequency selection circuit configured to determine a driving interval of the normal pulse SP, in which the rotation detector circuit is configured to instruct the frequency selection circuit to select a frequency corresponding to a position at which the detection signals DSand DShave been generated.

Provided is a drive circuit for a two-coil stepper motor, including a rotor that is magnetized to an N-pole and an S-pole, first, second, and third stator magnetic-pole portions, a coil A, and a coil B. The drive circuit includes a drive pulse generation circuit configured to output a drive pulse (SP) for driving the coil A and the coil B, a detection pulse generation circuit configured to output a detection pulse (CP) to the coil A and the coil B in order to detect counter-electromotive currents generated in the coil A and the coil B along with a movement of the rotor after the rotor is driven based on the drive pulse, and a detection circuit configured to receive a detection signal (CS) generated based on the detection pulse as input, to thereby detect the movement of the rotor. At least one of the detection pulse to the coil A or the detection pulse to the coil B is output.

Provided is an electronic timepiece, including: a step motor; a motor driver; a normal drive pulse generation circuit configured to output a normal drive pulse at a designated drive rank; a rotation detection pulse generation circuit configured to output a detection pulse; a rotation detection circuit which comprises at least a first detection mode determination circuit configured to conduct determination in a first detection mode and which is configured to detect rotation or non-rotation of a rotor; a rotation determination counter circuit configured to count a number of times that the rotation has been successively detected by the rotation detection circuit; a first detection mode determination counter circuit configured to count a number of times that a detection signal generated by the detection pulse becomes a predetermined detection pattern in the first detection mode; and a drive rank selection circuit configured to designate a drive rank of the normal drive pulse based on results of the counting conducted by the rotation determination counter circuit and the first detection mode determination counter circuit.

Growing community of inventors

Nishitokyo, Japan

Daisuke Iri