Stepping Motor Pulse Control for Analog Timepiece Rotor
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Solution Overview
Problem
Analog timepieces with dual-coil stepping motors face challenges in reliably controlling rotor rotation due to the inability to generate free vibration and inductive voltage, leading to potential missteps and unreliable unit step rotation.
Innovation Solution
The implementation of a control method that applies a pulse group including a rotary pulse and a braking pulse before the rotary pulse to the coil, allowing for precise control of rotor steps by ensuring free vibration and inductive voltage generation, using a stator with three magnetic pole portions and two coils to manage the rotor's rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a braking pulse is applied after a rotary pulse to prevent rotor overrun, then rotation reliability is improved, but free vibration cannot be generated and inductive voltage cannot be detected
Solution Approach 1:
The patent applies the braking pulse before the rotary pulse instead of after. This preliminary action prevents the rotor from overrunning before the rotation begins, allowing the rotor to still generate free vibration and inductive voltage during the subsequent rotary pulse operation, thus maintaining both rotation reliability and detection capability
Solution Approach 2:
The patent inverts the conventional sequence of pulses by applying the braking pulse first and then the rotary pulse, rather than the traditional rotary pulse followed by braking pulse. This reversal enables the rotor to maintain free vibration capability while still achieving reliable rotation control
2Adaptability or versatility
If holding torque of rotor is decreased to enable reverse rotation in fast-forward mode, then reversibility is improved, but the stepping motor is likely to be out of step
Solution Approach 1:
The patent applies a braking pulse before the rotary pulse to counteract the reduced holding torque effect. This preliminary braking action prevents the rotor from overshooting or missing steps, compensating for the lower holding torque caused by the dual-coil motor configuration used for reverse rotation capability
Solution Approach 2:
By applying the braking pulse in advance before the rotary pulse, the system prepares the rotor in a controlled state that compensates for the reduced holding torque, enabling reliable step-by-step rotation even with the dual-coil motor configuration that allows reverse operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables reliable detection of rotor rotation and correction of missteps, ensuring accurate unit step rotation and improved reliability in fast-forward mode operations by generating consistent inductive voltage.
Implementation Method 1
it is determined whether or not the rotor is rotated one unit step, based on an inductive voltage generated in the coil of the stator due to free vibration of the rotor
Implementation Method 2
a coil that excites the magnetic pole portion, and a control unit that controls each unit step of the rotor
Data Source
AI summary
There is provided an analog timepiece including an hour hand, a minute hand, and a second hand which are rotated by a unit step operation of a stepping motor. The analog timepiece includes a rotor that rotates the hour hand, the minute hand, and the second hand, and that has a magnetic polarity, a stator that includes magnetic pole portions disposed around the rotor, coils that excite the magnetic pole portions, and a control unit that controls each unit step of the rotor in accordance with each pulse group by applying a pulse group including a rotary pulse for rotating the rotor and a braking pulse for braking rotation of the rotor, which is applied before the rotary pulse is applied, to the coil.