Flexible Hand Actuation for Non-Circular Horological Dials
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Solution Overview
Problem
Conventional horological mechanisms fail to accurately and intuitively display time on non-circular watch dials, particularly the ovoid periphery, due to limitations in actuation mechanisms that restrict shape and length variation of flexible hands, limiting their ability to follow complex dial paths without significant design modifications or excessive deviation from circular shapes.
Innovation Solution
A novel actuation mechanism for flexible hands, involving a disk-driven system with a planetary wheel-holding frame and cam followers, allows the flexible hand to change shape and length by varying the angular position of its cannons, enabling the hand to describe two distinct paths over successive revolutions, with the cam follower finger traveling along a cam profile to achieve precise shape and length modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional circular hand path is used, then the mechanism is simple and reliable, but it cannot accurately display time on non-circular dials with ovoid periphery
Solution Approach 1:
The patent applies the dynamics principle by making the hand flexible rather than rigid, allowing it to dynamically change its shape and length during operation. The hand transitions from a straight configuration to a curved configuration following the ovoid dial periphery, enabling accurate time display on non-circular dials without complex actuation mechanisms.
Solution Approach 2:
The patent employs parameter changes by modifying the hand's geometric parameters (shape and length) to match the non-circular dial geometry. The hand's curvature and length are specifically designed to follow the ovoid periphery, transforming the hand from a standard circular-path component to one that adapts to elliptical motion requirements.
2Manufacturing precision
If the flexible hand shape and length are significantly modified to follow the ovoid periphery, then time display accuracy improves, but the hand deviates excessively from conventional circular shapes
Solution Approach 1:
The hand is designed to be flexible and dynamic, changing its shape only when necessary to follow the dial periphery. During part of its rotation, the hand maintains a conventional straight or slightly curved shape, while during other portions it adopts a more pronounced curve to match the ovoid geometry, thus balancing accuracy with recognizability.
Solution Approach 2:
The hand exhibits asymmetric shape characteristics, being straight or gently curved in some portions and more strongly curved in others, matching the asymmetric ovoid dial geometry. This asymmetric design allows the hand to conform to the non-circular dial while maintaining a familiar hand-like appearance in certain phases of rotation.
3Adaptability or versatility
If a complex actuation mechanism is designed to enable significant shape and length variation, then the hand can follow complex dial paths, but the mechanism becomes difficult to manufacture and sensitive to tolerances
Solution Approach 1:
The flexible hand is designed to be self-actuating, utilizing its own flexibility and elastic properties to change shape in response to rotational motion. The hand's intrinsic material properties and geometric design enable it to automatically conform to the dial periphery without requiring external actuators, complex mechanisms, or precise tolerance control.
Solution Approach 2:
The hand is constructed as a flexible element that can bend and deform elastically. This flexible construction allows the hand to change its shape and effective length by simply rotating, eliminating the need for complex mechanical actuation systems while maintaining ease of manufacture and robustness against tolerance variations.
4Adaptability or versatility
If the flexible hand is made more flexible to achieve greater shape variation, then it can follow the ovoid periphery more closely, but it becomes more susceptible to plastic deformation
Solution Approach 1:
The hand's flexibility parameters are precisely optimized to achieve the required shape variation while maintaining structural integrity. The material properties and cross-sectional geometry are specifically designed so that the hand can bend to follow the ovoid periphery within elastic limits, preventing plastic deformation while still achieving sufficient curvature for accurate time display.
Solution Approach 2:
The hand is made from a composite or specially formulated material that combines high flexibility with high yield strength. This material allows the hand to undergo repeated bending cycles to follow the non-circular dial path while resisting plastic deformation, ensuring long-term reliability and maintaining the elastic deformation principle.
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 accurate and aesthetically pleasing time display on non-circular dials, providing a robust and simple mechanism that maintains precise control over the flexible hand's shape and length, accommodating design modifications and ensuring minimal influence from manufacturing tolerances.
Implementation Method 1
a cam follower finger (186) arranged to travel along a profile (188) of a cam (190)
Implementation Method 2
a planetary wheel (184) which rotates on itself while being driven by the horological movement in a reduction ratio 1/2
Implementation Method 3
These flexible structures are composed of rigid elements connected to each other by flexible elements which are elastically deformed
Data Source
AI summary
A flexible hand actuation mechanism to which a disk of a horological movement applies a first angular rotation (θ1), the flexible hand including a first cannon and a second cannon connected to a point of the flexible hand via flexible arms, an operating position where the first cannon and the second cannon are coaxial about an exit axis, the first cannon being fitted with a first defined prestress angle, the second cannon being fitted with a second defined prestress angle of opposite direction to that of the first cannon, the actuation mechanism being arranged to actuate the flexible hand such that the latter changes shape and length in the desired manner by varying the angular position of the second cannon with respect to the first cannon by pivoting about the exit axis.