Position Encoder Dual Illumination Image Sensor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current position encoders face limitations in cost, accuracy, and alignment requirements, with low-cost encoders suffering from measurement drift and low accuracy, and high-cost encoders being prohibitively expensive and requiring tight optical alignment.
Innovation Solution
A position encoder system utilizing an image sensor and an encoded target pattern with a dual illumination system, allowing for high-resolution position detection at a lower cost with looser alignment requirements, using a two-dimensional array of detector elements and analyzing summed column and row outputs to monitor object position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-cost, low-resolution encoders use simple on-off shadowing for detecting position, then cost is reduced, but measurement accuracy and repeatability deteriorate
Solution Approach 1:
The patent transitions from one-dimensional linear scales used in traditional encoders to two-dimensional target patterns. This dimensional change enables the use of image sensors to capture and analyze spatial frequency information from the target pattern, significantly improving measurement accuracy and repeatability while maintaining cost-effectiveness through software-based processing rather than expensive hardware components.
2Measurement precision
If high-cost, high-resolution encoders use precision linear scales with diffraction and interferometry, then measurement accuracy is improved, but cost increases and optical alignment requirements become tighter
Solution Approach 1:
The patent replaces complex mechanical and optical measurement systems (diffraction gratings, interferometers, precision linear scales) with a digital image processing system. An image sensor captures the target pattern, and software algorithms analyze the spatial frequency content to determine position. This substitution eliminates tight optical alignment requirements while maintaining high measurement accuracy through computational methods.
3Ease of manufacture
If image correlation sensors use correlation methods on unstructured surfaces, then cost is reduced, but measurement drift and accuracy deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-structuring the target surface with a specific encoded pattern containing known spatial frequency information. This pre-structured target enables the image sensor to extract precise position data through Fourier analysis of the pattern's spatial frequencies, eliminating measurement drift associated with unstructured surfaces while maintaining cost-effectiveness.
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
The system provides high-resolution position detection with improved accuracy and tracking speed, reduced processing time, and relaxed alignment needs, enabling cost-effective and efficient monitoring of object position.
Implementation Method 1
The target pattern includes a plurality of first pattern elements that are reflective to the first illumination beam; and a plurality of second pattern elements that are reflective to the second illumination beam
Data Source
AI summary
A position encoder for monitoring position of an object includes a target pattern, an illumination system, an image sensor, and a control system. The illumination system generates (i) a first illumination beam that is directed toward and impinges on the target pattern, the first illumination beam having a first beam characteristic; and (ii) a second illumination beam that is directed toward and impinges on the target pattern, the second illumination beam having a second beam characteristic that is different than the first beam characteristic. The image sensor is coupled to the object and is spaced apart from the target pattern. The image sensor senses a first set of information from the first illumination beam impinging on the target pattern and senses a second set of information from the second illumination beam impinging on the target pattern. The control system analyzes the first set of information and the second set of information to monitor the position of the object.