Two-Axis Displacement Detection Device Origin Mark Elimination
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Solution Overview
Problem
Conventional two-dimensional position detection devices require origin marks in both X and Y directions, leading to increased costs and inaccuracies, particularly in optical systems using phase difference methods, which also necessitate two optical systems for one axis detection.
Innovation Solution
A two-dimensional displacement detection device that uses a single axis origin detection to generate absolute positions for both X and Y axes, eliminating the need for independent origin marks on the Y-axis and correcting optical distortion, allowing for accurate position detection without additional origin marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If origin marks are provided in both X and Y directions, then absolute position detection accuracy is improved, but device cost increases
Solution Approach 1:
The X-axis origin mark array serves dual purposes: it detects the origin position in the X direction and simultaneously enables absolute position detection in the Y direction. By making the origin mark array multi-functional, the patent eliminates the need for separate Y-axis origin marks while maintaining accurate absolute position detection capability in both directions.
Solution Approach 2:
The patent uses the X-axis origin mark array as a reference to generate Y-axis absolute position information through signal processing. Instead of physically copying origin marks to the Y-axis, the system creates a virtual origin reference for the Y-direction by utilizing the detected X-axis origin position and the known geometric relationship between the scale markings.
2Measurement precision
If phase difference method is used for optical position detection, then measurement precision is improved, but device complexity increases due to requiring two optical systems
Solution Approach 1:
The single optical system is designed to perform multiple functions: it reads both the X-axis and Y-axis scale markings and detects origin positions in both directions. By making the optical system multi-functional, the patent maintains nm-order detection accuracy while eliminating the need for separate optical systems for X and Y axes.
Solution Approach 2:
The patent combines the functions of reading X-scale, reading Y-scale, detecting X-origin, and detecting Y-origin into a single integrated optical system. This merging of functions reduces device complexity while maintaining the phase difference method's high precision capabilities for both axial measurements.
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 approach reduces costs by eliminating the need for separate origin marks on the Y-axis and maintains accurate absolute position detection, achieving comparable accuracy to devices with Y-axis origin marks while allowing for cost reduction.
Implementation Method 1
optical types (phase difference methods) have been recently proposed and executed
Implementation Method 2
optical types (phase difference methods) have been recently proposed and executed
Data Source
AI summary
Disclosed embodiments include a two-dimensional scale with a simple arrangement capable of omitting setting of an origin mark in the Y-axis direction. In a linear scale, a reference origin mark array and a tilting origin mark array that is a tilting marker array are provided in an origin mark region. Since the reference origin mark array is parallel to X-coordinates, an X-direction origin signal is correctly generated. On the other hand, for the Y direction in which no origin mark is provided, the distance between a reference origin mark and a tilting origin mark is detected. A Y-direction absolute position is decided in accordance with the distance.