Photoelectric Encoder Distortion Compensation via Virtual Array
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Solution Overview
Problem
Existing displacement detecting devices, such as photoelectric encoders, face high costs in increasing accuracy due to the need for customized design of light-receiving element arrays to counteract distortion caused by optical systems like lenses, which degrades position information detection efficiency.
Innovation Solution
A displacement detecting device with a movable light-receiving element array, a distortion compensation circuit, and a position analyzing circuit that corrects light/dark signals using a distortion table generated from optical system distortion information, allowing virtual adjustment of light-receiving element positions to eliminate distortion without physical movement, thereby enhancing detection accuracy at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the arrangement pitch of light-receiving elements is physically adjusted to counteract optical distortion, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent creates a virtual copy of the light-receiving element array in the form of a distortion table that stores corrected position information. Instead of physically adjusting the actual light-receiving elements, the system uses this virtual model to compensate for optical distortion, thereby maintaining measurement precision while avoiding the complexity of customizing physical hardware for each distortion pattern.
Solution Approach 2:
The patent replaces the mechanical/physical adjustment system with an information processing system. Rather than physically moving or repositioning light-receiving elements to counteract distortion, the system uses software-based distortion tables and signal correction algorithms to achieve the same effect, significantly reducing device complexity and manufacturing cost.
2Measurement precision
If customized light-receiving element arrays are designed for each distortion pattern, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the approach from modifying physical parameters (arrangement pitch of light-receiving elements) to modifying information parameters (distortion table data). By storing and processing distortion correction data in software rather than embedding it in hardware design, the system achieves high measurement precision while maintaining standard, cost-effective manufacturing processes.
Solution Approach 2:
The patent uses a virtual copy (distortion table) to represent and correct for optical distortion effects. This virtual model allows the system to compensate for various distortion patterns without requiring custom-designed light-receiving element arrays, thereby reducing manufacturing costs while maintaining detection accuracy.
3Measurement precision
If physical movement of light-receiving elements is used to correct distortion, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent completely replaces the mechanical movement system with an information processing system. Instead of physically moving light-receiving elements to correct distortion, the system uses distortion tables and software-based signal correction to achieve the same effect, eliminating the need for complex physical adjustment mechanisms.
Solution Approach 2:
The patent creates a virtual representation of the corrected element positions through distortion tables, allowing the system to achieve precise measurement without actual physical movement of components. This virtual copying approach maintains measurement precision while avoiding mechanical complexity.
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 effectively increases the accuracy of scale position information detection by canceling out optical system distortions at a lower cost, improving the efficiency of displacement measurement without the need for costly physical adjustments of light-receiving elements.
Implementation Method 1
an optical system configured to form an optical image of the scale pattern
Implementation Method 2
a light-receiving element array having a plurality of light-receiving elements which is configured to detect the image of the scale pattern and to output a light/dark signal
Data Source
AI summary
A photoelectric encoder includes a light-emitting element, a scale, a lens, a PDA, and a signal processing circuit. The signal processing circuit includes a distortion table, a distortion compensation circuit, and a position analyzing circuit. The distortion table is calculated in advance on the basis of pieces of distortion information that were obtained by a distortion simulation using design values of the optical system such as the lens. The distortion compensation circuit corrects a light/dark signal of the PDA by eliminating distortion caused by the optical system by changing the positions of the respective PDs of the PDA virtually on the basis of the distortion table and the pieces of position information of the respective PDs. The position analyzing circuit analyzes a position of the scale on the basis of the corrected light/dark signal.