Position Measuring Device Divergent Illumination Range Signal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing position measuring devices with divergent scale illumination struggle to generate a reliable range signal characterizing the relative position of a scanning unit in relation to a reference marking, as the known methods are not applicable for such configurations.
Innovation Solution
A position measuring device with a scale having a measuring graduation, a reference marking, and area markings, where a periodic aperture grating is arranged between the scale and the area signal detector, generating distinguishable scanning signals based on the position of the scanning unit relative to the reference marking, using a diffraction grating with specific periodicity and detector arrangements to produce a range signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a position measuring device uses divergent scale illumination, then the optical components can be more flexibly arranged, but the generation of a reliable range signal becomes difficult or impossible using known methods
Solution Approach 1:
The patent introduces a periodic aperture grating as an intermediary element between the scale and the area signal detector. This grating mediates the optical interaction by creating a stripe pattern from the area markings that can be reliably detected even under divergent illumination conditions, thus enabling range signal generation without compromising the flexible optical arrangement
Solution Approach 2:
The patent changes the parameters of the area markings by applying different deflection effects on the scanning beam for markings on opposite sides of the reference marking. This parameter change allows the system to distinguish between different areas and generate a reliable range signal despite the divergent illumination
2Measurement precision
If area markings are designed to be scanned optically with different deflection effects, then the scanning unit position can be distinguished, but the circuitry complexity increases
Solution Approach 1:
The patent extracts the position distinction function from complex circuitry by using optical methods. The periodic aperture grating and area markings create distinguishable stripe patterns that can be detected optically, removing the need for complex electronic processing while maintaining measurement precision
3Reliability
If a periodic aperture grating is introduced to generate stripe patterns, then range signal generation becomes reliable, but the device complexity increases
Solution Approach 1:
The periodic aperture grating serves multiple functions: it creates the stripe pattern for area detection, works with both reflective and diffraction grating area markings, and maintains functionality under divergent illumination. This multi-functionality justifies the added component by eliminating the need for separate processing steps and simplifying the overall system architecture
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
Enables reliable generation of a range signal that characterizes the relative position of the scanning unit in relation to the reference marking, even with divergent illumination, without requiring separate processing steps for the area markings and allowing for simple circuitry processing of scanning signals.
Implementation Method 1
A periodic aperture grating is arranged between the scale and the area signal detector and is designed and arranged such that the optical scanning of the area markings in the detection plane of the area signal detector results in a stripe pattern
Implementation Method 2
The area markings on the first and second sides of the reference marking exert different deflection effects on the scanning beam impinging thereon
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a position measuring device comprising a scale and a scanning unit movable relative to it in the measuring direction. The scale has at least one reference mark, wherein a reference signal can be generated by optical scanning of the reference mark. Furthermore, the scale has optically scannable area markings, wherein an area signal can be generated by optical scanning of the area markings with a scanning beam, by which it is possible to distinguish whether the scanning device is located on the first or the second side of the reference mark.Between the scale and a range signal detector, a periodic aperture grating is arranged, which is designed and arranged in such a way that, during the optical scanning of the range markings in the detection plane of the range signal detector, a stripe pattern results from which, depending on the position of the scanning unit relative to the reference marking, at least two distinguishable scanning signals can be generated (Fig. 3).