Watch Hand Position Detection Using Single Light Source
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Solution Overview
Problem
Existing devices for detecting the position of hands in electromechanical watches are bulky, complex, and costly due to the need for multiple light sources and detection systems, especially when trying to detect coaxial wheels or two distinct hands, which complicates manufacturing and integration into watch cases.
Innovation Solution
A compact hand position detection device using a single light source and two light detection systems mounted on or underneath the watch dial, with each hand having a reflective surface to direct the light beam towards its corresponding detection system, allowing precise detection of both hands with reduced component and assembly costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light sources and detection systems are arranged to detect two distinct hands, then detection precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the light source function by using a single light source to illuminate both hands, while separating the detection functions into two distinct detection systems. This reduces the number of light sources from two to one, simplifying the device structure and reducing manufacturing costs while maintaining the capability to detect both hands independently
Solution Approach 2:
The patent segments the detection function by providing two separate light detection systems positioned at different locations, each dedicated to detecting a specific hand. This segmentation allows independent detection of each hand's position, maintaining measurement precision while using a shared light source
2Reliability
If light sources and detection systems are arranged on both sides of the wheel plate, then detection capability is improved, but the device becomes bulky and requires more space
Solution Approach 1:
The patent combines the light source arrangement by placing a single light source on one side of the wheel plate, eliminating the need for light sources on both sides. The single light source illuminates both hands, and the two detection systems on the same side receive reflected light, reducing the overall device volume while maintaining detection reliability
Solution Approach 2:
The patent changes the spatial arrangement from a three-dimensional configuration with components on both sides of the wheel plate to a two-dimensional arrangement where all components are positioned on one side. This dimensional simplification reduces the device's thickness and overall volume
3Adaptability or versatility
If two light detection systems are placed between two coaxial wheels, then detection of both wheels is enabled, but automation of manufacture becomes practically impossible
Solution Approach 1:
The patent merges the illumination function by using a single light source that serves both detection paths, reducing the number of components that need to be precisely positioned between the wheels. This simplification makes the assembly process more amenable to automated manufacturing while maintaining the capability to detect both hands
4Measurement precision
If light source and detection system are arranged in stepped manner vertically, then detection function is achieved, but the device becomes bulky and requires recesses
Solution Approach 1:
The patent transitions from a vertical stepped arrangement requiring significant thickness to a planar arrangement where the light source and both detection systems are positioned on the same plane or on opposite sides of the wheel plate. This dimensional reorganization eliminates the need for deep recesses and reduces the device's overall length
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
Enables efficient and cost-effective detection of two distinct hands using a single light source, reducing the complexity and space requirements of the device while maintaining precision in hand positioning for synchronization.
Implementation Method 1
each hand having a reflective surface to direct the light beam towards its corresponding detection system
Data Source
AI summary
Device for detecting the position of at least a first and a second hand of an electromechanical watch, said first and second hands moving above a dial, the detection device including a single light source emitting a light beam towards the first and second hands, and a first and a second light detection system, the light source and the first and second light detection systems being mounted on or underneath the dial, the light source and the first and second light detection systems being arranged so that, in a determined position of the first hand, the light beam emitted by the light source is reflected by the first hand towards the first detection system, and in a determined position of the second hand, the light beam emitted by the light source is reflected by the second hand towards the second detection system.