Photoelectric Encoder Lens Array Image Reversal
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Solution Overview
Problem
Photoelectric encoders with telecentric optical systems face issues with image division and reversal, particularly affecting accurate shape reproduction in incremental and absolute types, where fluctuations in magnification and aberrations lead to distorted image patterns and shapes.
Innovation Solution
The introduction of a first lens array with pitches aligned to the main scale's period, accompanied by a second lens array for optical reversal and aperture placement at focal positions to form telecentric optical systems, along with electrical or optical re-reversal methods to correct image distortions, ensures accurate pattern and shape maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a lens array is used to reduce size and increase field of view, then the encoder size is reduced and FOV is increased, but the image is divided and reversed in each single lens optical system
Solution Approach 1:
The patent applies optical inversion by introducing a second lens array that reverses the image division and reversal caused by the first lens array. The second lens array is configured with the same pitch as the first lens array, and its optical path is arranged to invert the distorted image, thereby restoring accurate image patterns while maintaining the compact size and increased FOV benefits of the lens array configuration.
2Length of stationary object
If the focal position of the third lens array is made smaller than the first and second lens arrays, then the entire optical length is shortened, but the complexity of the optical system increases
Solution Approach 1:
The patent implements nesting by positioning the third lens array with a shorter focal length between the first and second lens arrays, creating a compact nested optical configuration. The third lens array is integrated into the optical path between the other two lens arrays, allowing the system to achieve reduced overall length while maintaining the necessary optical functions for image reversal and correction.
3Stability of the object's composition
If aperture is positioned at focal position of the lens to control magnification fluctuations, then magnification stability is improved, but the system is sensitive to positional changes
Solution Approach 1:
The patent applies local quality by positioning apertures at the focal positions of individual lenses within the lens arrays. Each lens has its own aperture positioned at its focal point, allowing local control of magnification for each optical element. This localized approach enables magnification stabilization while providing flexibility in the overall system configuration.
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 configuration maintains image patterns and shapes by aligning lens pitches with the main scale's period and using optical or electrical reversal techniques, effectively addressing the issues of image division and reversal, applicable to both incremental and absolute types of photoelectric encoders.
Implementation Method 1
a lens array 46 is used as the lens 42
Implementation Method 2
a lens optical system (telecentric optical system) 40, comprising a lens 42 and an aperture 44 that functions as a telecentric optical diaphragm
Implementation Method 3
light receiving element array 34 constituting a light receiving unit 30
Data Source
AI summary
A photoelectric encoder is provided which has an optical system including a first lens array inserted between a main scale and a light receiving element. An image divided or reversed by the first lens array can be electrically or optically re-reversed. This can achieve the reduction of the entire size as well as increase in the scale field of view, while maintaining the image shape and/or pattern.