Reflective Multi-Turn Encoder Solid Gear Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-turn optical encoders face challenges in being compact, cost-effective, and precise due to mechanical construction limitations, and they are unable to sense partial revolutions of constituent disks, with magnetic encoders being susceptible to external fields and temperature limitations.
Innovation Solution
A reflective multi-turn optical encoder sub-module design featuring a gear with no apertures or holes, a geared rotatable shaft, and a substrate with optically reflective and non-reflective areas, and light detectors configured to produce output signals out of phase, allowing for compact, precise manufacturing and sensing of partial revolutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gears with openings or holes are used for light to pass through, then light transmission is enabled, but the gears cannot be packed close together and precision is limited
Solution Approach 1:
The patent replaces the mechanical aperture-based light transmission system with a reflective optical system. Instead of using gears with holes that require precise mechanical alignment and have minimum spacing requirements, the invention uses solid gears with reflective surfaces that redirect light to detectors. This substitution eliminates the need for light to pass through gear openings, allowing gears to be packed closer together while maintaining or improving precision.
2Strength
If substrates are added on both sides of the gear train for mechanical integrity, then structural strength is improved, but device complexity and size increase
Solution Approach 1:
The patent merges the substrate functions by using a single substrate that serves multiple purposes: providing mechanical support for the gear train and housing the optical detectors. Instead of requiring separate substrates on both sides of the gear train, the design integrates the detector array into one substrate, reducing the number of components and simplifying the overall structure while maintaining mechanical integrity.
3Measurement precision
If traditional optical encoders are designed, then multi-turn sensing is achieved, but partial revolutions of constituent disks cannot be sensed
Solution Approach 1:
The patent adds a temporal dimension to the optical sensing by implementing a pulsed light emission scheme. The light source emits light in pulses synchronized with the rotation of the code disk, allowing the system to detect not only the position but also the rotational speed and direction. This enables the encoder to sense partial revolutions by measuring the time between pulses and the phase change in reflected light, providing comprehensive rotational information beyond full turns.
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 the creation of compact, cost-effective optical encoders that can accurately sense partial revolutions without external interference, enhancing precision and manufacturing feasibility.
Implementation Method 1
at least portions of the light emitted by the light emitter and incident on the first area are reflected towards at least portions of the first and second arrays of light detectors for detection thereby
Implementation Method 2
at least portions of the light emitted by the light emitter and incident on the second area are substantially not reflected from the second area and are not detected by the first or second arrays of light detectors
Data Source
AI summary
Disclosed herein are a number of different embodiments of reflective multi-turn optical encoders with different light sensing systems. Three different basic configurations of reflective multi-turn optical encoder light sensing systems are disclosed herein: (a) optical encoders employing multiple arrays of light detectors; (b) optical encoders employing multiple arrays of stacked die light sensors, and (c) optical encoders employing variable tone density light sensing systems.