Analog Timepiece Pointer Positioning Backlash Elimination
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Solution Overview
Problem
Analog electronic timepieces face challenges in accurately adjusting the position of pointers due to backlash in gear train mechanisms, especially during fast forwarding operations, leading to discrepancies between predicted and actual pointer positions.
Innovation Solution
The implementation of a control system that includes a stepping motor, gear train mechanism, drive control unit, control content changing unit, rotation direction determination unit, and pointer position adjustment unit, which allows for mid-operation adjustments and backlash removal by determining reverse rotation needs and performing position corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the gear train mechanism is designed with gaps (backlash) between gears to accommodate temperature variation and aging, then the mechanism can be modified slightly due to environmental factors, but rotation cannot be transmitted accurately to the pointer when the first gear is rotated, especially in reverse direction
Solution Approach 1:
The control unit performs preliminary rotation of the pointer in the reverse direction before fast forwarding to eliminate backlash gaps. This preliminary action ensures that when the pointer needs to move in the fast forwarding direction, the gear mesh is already engaged without gaps, eliminating position errors.
Solution Approach 2:
The control unit monitors the rotation direction and position of the pointer, and based on this feedback, dynamically adjusts the control signal to the stepping motor. When reverse rotation is detected, the control unit adds preliminary reverse rotation steps to compensate for backlash, ensuring accurate pointer positioning.
2Productivity
If the pointer is moved quickly to the target position during fast forwarding operation, then operational efficiency is improved, but different fast forwarding movements may be started while the pointer is moving, causing the influence of backlash to persist and the pointer position to differ from the predicted position
Solution Approach 1:
Before executing fast forwarding movement, the control unit determines the current rotation direction and performs preliminary reverse rotation to eliminate backlash. This ensures that even when multiple fast forwarding commands are issued during operation, the pointer starts from a position where backlash has been eliminated.
Solution Approach 2:
The control unit dynamically adjusts the fast forwarding operation based on the current state of the pointer and gear train. When reverse rotation is detected in the series of operational controls, the control unit dynamically adds backlash elimination steps, allowing the system to maintain accuracy while responding to changing operational demands.
3Measurement precision
If the motor is operated in advance for the number of steps corresponding to the gaps to remove backlash influence, then pointer position accuracy is improved, but time is consumed before the pointer can respond to rotation commands
Solution Approach 1:
The control unit performs preliminary reverse rotation only when reverse rotation is detected in the series of operational controls. This conditional preliminary action eliminates backlash only when necessary, maintaining pointer position accuracy while minimizing the time penalty to only when it is actually needed.
Solution Approach 2:
The control unit dynamically determines whether backlash elimination is needed by monitoring the rotation direction in the series of operational controls. This dynamic approach allows the system to adapt to actual operating conditions, performing preliminary rotation only when reverse rotation occurs, thus balancing accuracy requirements with response time constraints.
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 pointer positioning by addressing backlash issues, reducing time lag, and improving operational efficiency during fast forwarding and function switching in analog electronic timepieces.
Implementation Method 1
a stepping motor, a gear train mechanism for transmitting rotation which is input from the stepping motor
Data Source
AI summary
An analog electronic timepiece includes a stepping motor, a gear train mechanism having gears, a pointer, a drive control unit, a control content changing unit, and a pointer position adjustment unit. If an operational command to rotate the pointer to a different moving target position is obtained while an operational control for rotating the pointer to a certain moving target position is in progress, the control content changing unit terminates the control and changes a control content to an operational control according to the command. If the reverse rotation driving operation is being performed, the pointer position adjustment unit performs an adjustment operation for removing shifting between a predicted position of the pointer and an actual position of the pointer which occurs because of rotational input from the stepping motor not being transmitted to the pointer due to gaps relating to the mesh of the gears.