Stepping Motor Control Using Induced Voltage Feedback
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Solution Overview
Problem
Analog electronic timepieces with stepping motors face limitations in speeding up hand movement due to the need to brake pointers to prevent step-out, restricting the speed of hand movement adjustments.
Innovation Solution
An analog electronic timepiece with a stepping motor that applies a drive pulse to the rotor before free vibration settles, based on induced voltage conditions, to control the drive pulse width or duty ratio, ensuring the pulse is applied before the rotor's vibration stabilizes, thereby enhancing hand movement speed while suppressing step-out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the stepping motor is moved at a higher speed for fast-forwarding hand movement, then the hand movement speed is improved, but step-out occurs requiring braking time that limits the speed increase
Solution Approach 1:
The control unit applies a drive pulse to the driving coil before the free vibration of the rotor is settled, proactively maintaining synchronization between the drive pulse and rotor position. This preliminary action prevents step-out from occurring in the first place, eliminating the need for subsequent braking operations and enabling continuous high-speed hand movement.
Solution Approach 2:
The control unit monitors the induced voltage generated by rotor rotation and uses this feedback to determine when to apply the drive pulse. By detecting the induced voltage polarity and magnitude, the control unit synchronizes the drive pulse application with the rotor's actual position and vibration state, ensuring reliable operation at high speeds without step-out.
2Speed
If the drive pulse is applied before free vibration settles, then hand movement speed is increased, but control precision may be compromised
Solution Approach 1:
The control unit uses induced voltage feedback to precisely time the drive pulse application. By monitoring the induced voltage polarity and magnitude, the control unit accurately determines the rotor's instantaneous position and vibration state, enabling precise control even when applying pulses before vibration settles. This feedback mechanism ensures that the 'before vibration settles' timing does not compromise position control precision.
Solution Approach 2:
The control unit dynamically adjusts the drive pulse parameters (width, duty ratio) based on the detected induced voltage and rotor operation state. This parameter adaptation allows the system to maintain precise control across different operating conditions, including the high-speed regime where pulses are applied before vibration settles, by optimizing pulse characteristics for each specific state.
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 solution allows for increased hand movement speed in analog electronic timepieces while preventing step-out, ensuring stable and efficient operation during fast-forwarding hand movement modes without the need for additional detection coils.
Implementation Method 1
an induced voltage induced in the driving coil by rotation of the rotor
Data Source
AI summary
There is provided an analog electronic timepiece including a stepping motor in which a rotor magnetized in two poles is rotationally driven in a stator connected to a driving coil, a drive circuit for applying a drive pulse to the driving coil, the drive pulse being a pulse for driving the rotor, and a control unit for controlling application of the drive pulse by the drive circuit, in which when an induced voltage induced in the driving coil by rotation of the rotor satisfies a predetermined condition related to the induced voltage, the control unit controls the drive circuit so that the drive pulse is applied to the driving coil before free vibration of the rotor is settled.