Timepiece Movement with Variable Contact Wheel for Hand Malfunction Prevention
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Solution Overview
Problem
Conventional electronic timepieces with indicator hands can experience malfunctions due to the indicator hand deviating from its normal rotational range, causing it to abut the shaft of hour/minute hands, leading to a stuck state where the rotor fails to rotate even with motor pulses applied.
Innovation Solution
A timepiece movement featuring a first wheel with a hand-mounted hand, a first motor for driving the first wheel, a second wheel with a variable contact portion on its outer surface that allows the hand to either create a gap or displace when contacting the second wheel, and a second motor to drive the second wheel, enabling rotation even when the hand is initially unrotatable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the indicator hand is designed to rotate within a limited range to avoid contact with the shaft portion of hour/minute hands, then the risk of contact malfunction is reduced, but the indicator hand may still abut the shaft portion due to unexpected situations such as excessive pulses
Solution Approach 1:
A second wheel with a contact portion is introduced as an intermediary mechanism between the indicator hand and the shaft portion of hour/minute hands. The contact portion has a variable distance from the rotation axis, creating a controlled interaction that prevents direct harmful contact while allowing the hand to be guided back to the normal rotational range through rotation of the second wheel.
Solution Approach 2:
The distance of the contact portion from the rotation axis of the second wheel varies in accordance with the position in the peripheral direction. This parameter change allows the contact portion to provide different levels of interaction - creating gaps when needed and providing gentle guidance - thereby adapting to different operational states without causing malfunction.
2Ease of operation
If the indicator hand comes into contact with the shaft portion of hour/minute hands, then the hand may be pushed out of normal rotational range, but this contact causes the rotor to become stuck and unrotatable
Solution Approach 1:
The second wheel with its contact portion serves as a mediator that intercepts the indicator hand before it can contact the shaft portion of hour/minute hands. By providing a controlled contact point with variable distance from the rotation axis, it guides the hand back to the normal rotational range, preventing the rotor from becoming stuck.
Solution Approach 2:
The potential harmful contact between the indicator hand and the shaft portion is converted into a beneficial interaction through the second wheel. The contact portion designed with variable distance from the rotation axis transforms what would be a damaging direct contact into a controlled mechanism that restores proper hand positioning and prevents rotor malfunction.
3Device complexity
If a single motor is used to drive both the indicator hand and correct its position, then the device complexity is reduced, but the ability to reliably escape stuck states is compromised
Solution Approach 1:
The driving function is segmented into two separate motors: the first motor drives the indicator hand wheel for normal operation, while the second motor drives the correction wheel for position correction. This segmentation allows each motor to perform its specific function reliably without the conflicts that would arise from a single motor attempting to perform both functions.
Solution Approach 2:
The second wheel acts as an intermediary mechanism driven by the second motor, separate from the primary driving system. This intermediary structure enables position correction without interfering with the normal operation of the first motor, thereby maintaining reliability in escaping stuck states while managing device complexity.
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 design effectively prevents malfunctions by allowing the rotor to rotate even when the hand is initially stuck, ensuring reliable operation by creating a gap or displacing the hand, thus overcoming the issue of the rotor becoming unrotatable.
Implementation Method 1
a stepping motor that rotates and drives the rotor in both directions
Data Source
AI summary
A timepiece movement capable of suppressing generation of malfunction of a hand is provided. The movement includes an indicator hand wheel which is provided so as to be rotatable and to which an indicator hand is mounted; an indicator hand stepping motor rotating and driving the indicator hand wheel in both directions; an hour wheel provided so as to be rotatable around a first rotation axis different from a rotation axis of the indicator hand wheel and having a first shaft portion which extends along the first rotation axis and on the outer peripheral surface of which there is provided a contact portion that the indicator hand can abut, with the distance of the contact portion from the first rotation axis varying in accordance with a position in the peripheral direction around the first rotation axis; and an hour hand stepping motor rotating and driving the hour wheel and provided separately from the indicator hand stepping motor.