Stepping Motor Reverse Rotation Control via Voltage-Adaptive Pulse Width
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Solution Overview
Problem
Stepping motors in timepieces face accuracy issues during reverse rotation due to variations in voltage applied to their coils, making it difficult to maintain precise rotation across different power sources.
Innovation Solution
Incorporating a voltage detection unit and a control system that adjusts the pulse width and polarity of the reverse rotation pulse based on detected voltage, using a combination of first, second, and third pulses with specific pulse widths and polarities to ensure accurate reverse rotation, and storing correspondence tables for pulse widths across varying voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stepping motor is used to drive an indicating hand, then the timepiece can operate the indicating hand, but the rotor cannot accurately perform reverse rotation when voltage applied to the coil changes
Solution Approach 1:
The patent applies dynamics by making the pulse width of the third pulse variable based on the detected voltage level. Instead of using a fixed pulse width, the control unit adjusts the pulse width dynamically according to the voltage detected during reverse rotation, allowing the system to adapt to different voltage conditions and maintain accurate rotor positioning across various power sources.
Solution Approach 2:
The patent changes the parameter of pulse width based on voltage detection results. By detecting the voltage level during reverse rotation and selecting an appropriate pulse width from predetermined options, the system optimizes the magnetic field generation for each voltage condition, ensuring accurate rotor control regardless of voltage variations from different power sources.
2Reliability
If a complicated reverse rotation pulse is applied to achieve reverse rotation, then the rotor can be reversed, but the operation becomes more complex and accuracy decreases when voltage changes
Solution Approach 1:
The patent applies preliminary action by pre-determining multiple pulse width values corresponding to different voltage levels before actual operation. The control unit stores these predetermined pulse widths and simply selects the appropriate one based on voltage detection, avoiding the need for complex real-time calculations or adjustments during reverse rotation execution.
Solution Approach 2:
The patent uses periodic action by applying a sequence of pulses with different widths in a predetermined order based on voltage detection. The reverse rotation pulse consists of multiple phases (first pulse, second pulse, third pulse) where each phase has a specific pulse width selected according to the detected voltage, creating a structured and repeatable control pattern.
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
Ensures accurate and reliable reverse rotation of the rotor even with changes in applied voltage, preventing step-out and maintaining rotation accuracy across different power sources.
Implementation Method 1
a voltage detection unit that detects a voltage applied to a stepping motor for driving an indicating hand, and that outputs a voltage detection result
Implementation Method 2
A rotor of the stepping motor performs normal rotation or reverse rotation, if a pulse output from a drive control unit (driver IC) is applied to a coil
Data Source
AI summary
A timepiece includes a voltage detection unit that detects a voltage applied to a stepping motor for driving an indicating hand, and that outputs a voltage detection result, and a drive control unit that controls a rotor to perform reverse rotation by using a reverse rotation pulse including a first pulse whose polarity is the same as that of a normal rotation pulse for causing the rotor of the stepping motor to perform normal rotation, a second pulse whose polarity is reverse to that of the first pulse, and a third pulse whose polarity is reverse to that of the second pulse, and to control the rotor to perform the reverse rotation by using the third pulse having a pulse width set in accordance with the voltage detection result.