Cam and Feeler Mechanism for Accurate Positioning
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Solution Overview
Problem
Watch mechanisms with cams face positioning errors due to manufacturing tolerances and clearance in the kinematic chain, leading to inaccurate information reading, particularly in transition zones between steps, and existing solutions either increase bulk or energy consumption.
Innovation Solution
A watch mechanism with a cam featuring notches or protuberances on its periphery and a probe that adjusts the angular position by inserting into these features, allowing precise reading while minimizing volume and energy consumption, and correcting positioning errors by averaging support points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surprise device is added to extend the highest step of a snail cam, then reading errors are avoided, but the mechanism becomes bulky and consumes more space
Solution Approach 1:
The invention extracts the error-prevention function from a separate mechanical device (surprise) and integrates it directly into the cam structure through asymmetric notches. The notch geometry itself provides the blocking function, eliminating the need for additional extending components and reducing overall cam thickness.
Solution Approach 2:
The invention merges the information storage function (cam steps) with the error-prevention function (blocking mechanism) into a single integrated structure. The asymmetric notch design combines both functions in one element, eliminating the separate surprise device and reducing mechanical complexity.
2Manufacturing precision
If spring-toothed wheels or eyelash wheels are used to minimize backlash, then positioning precision is improved, but energy consumption increases making them unsuitable for low-torque mobiles
Solution Approach 1:
The invention replaces complex mechanical adjustment systems (spring-toothed wheels, eyelash wheels) with a simpler asymmetric notch geometry. The positioning correction is achieved through the fixed geometric design of notches at different radial distances, eliminating the need for active mechanical adjustment mechanisms and reducing energy consumption.
Solution Approach 2:
The invention changes the geometric parameters of the notches (asymmetric positioning at different radial distances from the rotation axis) to inherently provide positioning correction. This passive geometric solution replaces active mechanical adjustment systems, reducing both complexity and energy consumption.
3Measurement precision
If the cam is positioned precisely to avoid reading errors in transition zones, then reading accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention incorporates error-prevention features directly into the cam's manufactured geometry through asymmetric notches. The positioning correction is built into the design itself, eliminating the need for post-manufacturing adjustment or extremely tight tolerance control, thereby simplifying manufacturing while ensuring accurate reading.
Solution Approach 2:
The asymmetric notch design provides a built-in safety mechanism that compensates for positioning variations before they can cause reading errors. The geometry of the notches at different radial distances inherently prevents erroneous readings even when positioning is not perfectly precise, cushioning against manufacturing variations.
Data Source
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AI summary
A clockwork mechanism comprising a cam (1) for measuring and/or storing information, mounted for rotation about an axis of rotation (10) and comprising either a plurality of notches (11) or a plurality of protrusions on its periphery, a feeler (2) for reading information on the cam (1), the feeler comprising respectively either a protrusion or a notch, the reading of information on the cam (1) by the feeler (2) being effected by movement of the feeler (2) towards the cam (1) and either insertion of the protrusion of the feeler (2) into a notch (11) of the plurality of notches (11) or insertion of a protrusion of the plurality of protrusions into the notch of the feeler, the feeler (2) and the cam (1) being configured such that during the movement of the feeler (2) and insertion of the protrusion into the notch (11),The feeler (2) adjusts the angular position of the cam (1) to a reading position in which the insertion of the protrusion into the notch (11) is stopped by the profile (12, 13) of the notch (11) and the cam (1) is prevented from rotating by the feeler (2), at least two notches (11) of the plurality of notches (11) or at least two protrusions of the plurality of protrusions being configured so that, in the reading position, the feeler (2) is at different distances from the axis of rotation (10) of the cam (1). A timepiece comprising such a mechanism and a method for reading information and adjusting the angular position of such a mechanism.