Rotary Reflector Angular Position Sensor for Watch Shafts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for determining angular movement parameters of a rotating axis in timepieces, such as quartz watches, face challenges with high processing times and power consumption due to the large number of data required, which is problematic in constrained spaces like watches.
Innovation Solution
An electro-optical system with a rotary reflector and two emitter-detector pairs arranged in a specific spatial configuration generates sinusoidal signals, allowing for reduced processing power and fast determination of angular movement parameters with minimal data, using a processor that represents signals as sine and cosine to calculate arctangent functions for precise angular position and direction determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electro-optical device with a reflective surface and light detector is used to determine angular movement parameters, then the angular position and direction of rotation can be determined, but the processing time becomes relatively long due to the amount of data acquired
Solution Approach 1:
The reflective surface is segmented into multiple reflective surfaces arranged at different angular positions around the rotation axis. Each reflective surface reflects light to a corresponding light detector, creating multiple independent measurement channels. This segmentation allows the system to determine angular position using data from multiple discrete points rather than processing continuous large-volume data, thereby reducing processing time while maintaining measurement precision.
Solution Approach 2:
The system uses a number of light detectors that is sufficient to determine angular position and direction of rotation but not excessive. By carefully selecting the number and arrangement of detectors corresponding to the segmented reflective surfaces, the system acquires just enough data to achieve accurate measurement without the overhead of processing unnecessary additional data, thus optimizing the balance between precision and processing speed.
2Measurement precision
If sufficient power is provided for the processor to handle large data amounts, then accurate determination of angular movement parameters is achieved, but the overall size of the device increases
Solution Approach 1:
The measurement system is divided into multiple independent segments (reflective surfaces and detectors), each contributing discrete measurement data. This segmentation reduces the total volume of data requiring processor handling compared to continuous full-field measurement, allowing a smaller, lower-power processor to achieve the same measurement precision with reduced size and power consumption.
Solution Approach 2:
The system changes the measurement approach from continuous data acquisition to discrete point measurement using multiple detectors. This parameter change in the measurement methodology reduces the data volume that must be processed, enabling the use of a more compact processor while maintaining accurate determination of angular movement parameters.
3Reliability
If available space and energy are limited within a watch, then the system size and energy consumption are constrained, but providing sufficient processing power for large data amounts becomes problematic
Solution Approach 1:
The measurement system processes data from multiple discrete reflective surfaces and detectors rather than continuous large-volume data. This segmentation reduces the computational burden on the processor, lowering energy consumption and extending system autonomy while maintaining reliable angular position and direction determination within the space-constrained watch environment.
Solution Approach 2:
The system acquires and processes only the minimum necessary data from the segmented reflective surfaces and detectors required to determine angular position and direction of rotation. This avoids excessive data processing, reducing processor energy consumption and preserving battery life, thereby improving system autonomy without sacrificing measurement reliability.
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 enables accurate and efficient determination of angular position and direction of rotation with reduced power consumption and processing time, suitable for the limited resources of a timepiece.
Implementation Method 1
The device comprises a light source intended to illuminate the reflective surface, as well as a light detector intended to receive a beam of reflected light from the reflective surface
Implementation Method 2
a light detector intended to receive a beam of reflected light from the reflective surface and to generate an electrical signal representative of the beam
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The system (6) and the method are designed to determine the angular motion of a shaft (4) attached to a crown (2) of a watch (1), the shaft being able to rotate about its own axis along a longitudinal direction (D1). The system comprises a rotating reflector (8) mounted on the shaft, and two pairs (10A, 10B) of emitter-detectors arranged on either side of the reflector. Each emitter-detector pair includes a light source (16) to illuminate the reflector, and a light detector (18) to receive the light reflected (24) from the reflector and to generate an electrical signal representative of the reflected light. The system further includes a processor to process the electrical signals generated by the detectors and to determine a parameter relating to the angular motion of the shaft.The rotating reflector has a shape such that its apparent outer surface, seen from each transmitter-detector pair and which forms an active reflective part of the reflector for said pair, evolves when the reflector rotates on itself, in such a way that the representative electrical signal generated by said detector of the pair has a substantially sinusoidal shape when the reflector rotates on itself regularly in the same direction of rotation (S1, S2).