Optical Positioning Device Reference Pulse Signal Secondary Maxima
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Solution Overview
Problem
Existing optical position measuring devices face challenges in reliably detecting reference pulse signals due to pronounced secondary maxima, which reduce the signal-to-noise ratio and uncertainty in identifying the actual signal maximum at reference positions.
Innovation Solution
The introduction of additional structures with specific optical properties, such as non-transparent and transparent areas in transmitted-light systems, or slightly reflective and highly reflective areas in reflected-light systems, adjacent to the reference marking, to minimize secondary maxima in the reference pulse signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional structures are added adjacent to the reference marking to suppress secondary maxima, then the reliability of reference pulse signal detection is improved, but the device complexity increases
Solution Approach 1:
The additional structure is segmented into multiple tracks (at least two) with different optical properties arranged adjacently. Each track contains specific patterns (transparent/non-transparent or reflective/non-reflective areas) that work together to suppress secondary maxima while maintaining the reference pulse signal, thereby improving detection reliability without excessive complexity
Solution Approach 2:
The additional structure implements local quality by creating specific optical property variations in localized regions adjacent to the reference marking. The tracks have different optical characteristics (transparent vs. non-transparent, or reflective vs. non-reflective) in specific areas to target the suppression of secondary maxima at precise locations where they occur
2Measurement precision
If the reference marking uses aperiodic arrangement of partial areas with different optical properties, then the reference pulse signal generation is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The reference marking employs an aperiodic (asymmetric) arrangement of partial areas with different optical properties instead of a regular periodic pattern. This asymmetric configuration optimizes the reference pulse signal generation by suppressing secondary maxima through the specific non-repeating sequence of transparent/non-transparent or reflective/non-reflective areas
Solution Approach 2:
The additional structure with pre-configured tracks and patterns is designed and manufactured in advance adjacent to the reference marking. The specific arrangement of transparent/non-transparent or reflective/non-reflective areas is predetermined to automatically suppress secondary maxima when scanned, preparing the optical path before measurement occurs
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 ensures a reference pulse signal with minimized secondary maxima, allowing for reliable detection of the signal maximum at reference positions, enhancing the detection reliability and accuracy of position measurements.
Implementation Method 1
The scanning unit comprises a light source, a reference pulse detector arrangement... The reference pulse detector arrangement consists of individual optoelectronic detector elements... When the reference marking is passed over, a signal maximum of the reference pulse signal now results
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
An optical position measuring device is described, which serves to determine the relative position of two objects moving in a measuring direction (x) relative to each other, wherein a reference pulse signal can be generated at at least one defined reference position. The position measuring device comprises a scale connected to one of the two objects and which has a reference mark at the reference position. This reference mark consists of a plurality of sub-areas with different optical properties arranged aperiodically in the measuring direction. Adjacent to the reference mark in the measuring direction are additional structures that extend in the measuring direction and minimize the secondary maxima in the resulting reference pulse signal.Furthermore, the position measuring device comprises a scanning unit movable relative to the scale in the measuring direction, which is connected to the other object, with a light source and a reference pulse detector arrangement consisting of individual detector elements whose geometric arrangement is adapted to the reference mark for generating a reference pulse signal. The additional structures comprise at least two tracks with a first optical property, between which a section extending in the measuring direction with a second optical property is arranged (Figure 2b).