Optical Rotation Angle Detection in Surveying Instruments
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Solution Overview
Problem
Current rotation angle detecting apparatuses in surveying instruments face challenges in achieving high accuracy due to fabrication errors, runout issues, and high costs associated with precise encoders, which are exacerbated by the need for fine adjustments and high installation accuracy.
Innovation Solution
A rotation angle detecting apparatus featuring a bearing holder, rotation shaft, angle detection pattern, reference pattern, image sensor, optical system, and arithmetic device that calculates rotation angles based on signal deviations from the image sensor, allowing for accurate detection without relying on the installation accuracy of the image sensor and enabling runout measurement, thus reducing costs and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a highly accurate encoder is used for angle detection, then angle detection accuracy is improved, but cost increases and assembly complexity increases due to fine adjustment requirements
Solution Approach 1:
The patent replaces the mechanical encoder system with an optical detection system consisting of a scale, illumination unit, and image sensor. This substitution eliminates the need for mechanical fine adjustments and runout compensation mechanisms, thereby reducing assembly complexity while maintaining high angle detection accuracy through optical field measurements.
Solution Approach 2:
The patent creates an optical copy of the scale pattern through illumination and projects it onto an image sensor. This copying mechanism allows angle detection without direct mechanical contact or precise mechanical alignment, eliminating the need for fine adjustment of mechanical components while preserving measurement accuracy.
2Measurement precision
If a highly accurate encoder is used for angle detection, then angle detection accuracy is improved, but cost increases
Solution Approach 1:
The patent employs inexpensive optical components (scale, illumination unit, image sensor) that can be manufactured at low cost using standard semiconductor and optical fabrication techniques. These components replace expensive precision encoders while achieving comparable or superior accuracy, directly reducing manufacturing cost.
Solution Approach 2:
By replacing the mechanical encoder with an optical detection system, the patent eliminates the need for expensive precision mechanical manufacturing and assembly processes. The optical system can be manufactured using standard photolithography and optical assembly techniques, significantly reducing production costs while maintaining high measurement accuracy.
3Measurement precision
If fine adjustment and fine finishing in assembly state are performed to achieve high accuracy, then angle detection accuracy is improved, but cost increases and productivity decreases
Solution Approach 1:
The optical detection system requires no mechanical fine adjustment or fine finishing during assembly. The scale, illumination unit, and image sensor can be assembled using standard tolerance ranges, eliminating time-consuming manual adjustment processes and significantly improving assembly efficiency and productivity.
Solution Approach 2:
The optical system automatically compensates for minor assembly variations and misalignments through its optical field measurement mechanism. The image sensor captures the scale pattern regardless of small positional deviations, eliminating the need for manual fine adjustment and enabling rapid assembly without sacrificing measurement accuracy.
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 apparatus achieves highly accurate angular detection and runout measurement, reducing the need for expensive encoders and precise component alignment, thereby lowering costs and enhancing the accuracy of angle detection in surveying instruments.
Implementation Method 1
an optical system which exists across the shaft portion space and the bearing holder space and forms a projection image of the angle detection pattern and a projection image of the reference pattern on the image sensor
Implementation Method 2
an image sensor provided in the bearing holder space... an arithmetic device for calculating a rotation angle of the rotation shaft based on a signal from the image sensor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A rotation angle detecting apparatus comprises a bearing holder 3, a rotation shaft 1 rotatably supported by the bearing holder, a shaft portion space 4 formed in the rotation shaft, a bearing holder space 6 formed in the bearing holder, an angle detection pattern 8 accommodated in the shaft portion space, a reference pattern 16 provided in the bearing holder space, an image sensor 13 provided in the bearing holder space, an optical system 9, 11, 12, 15 which exists across the shaft portion space and the bearing holder space and forms a projection image of the angle detection pattern and a projection image of the reference pattern on the image sensor, a photodetection switching means 19, 20 for selectively projecting the projection image of the angle detection pattern and the projection image of the reference pattern onto the image sensor, and an arithmetic device 21 for calculating a rotation angle of the rotation shaft based on a signal from the image sensor, and in the rotation angle detecting apparatus, the arithmetic device detects the rotation angle of the rotation shaft based on a deviation between a signal from the image sensor which has received the reference pattern and a signal from the image sensor which has received the angle detection pattern.