Position Measuring Device Merging Absolute and Incremental Tracks
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Solution Overview
Problem
Existing position measuring devices are complex and costly due to the need for two independent position detection units, which is undesirable from a safety and cost perspective.
Innovation Solution
A position measuring device comprising a code carrier with both an absolute and an incremental graduation track, where the incremental graduation track's position signals are processed to generate a second absolute position value, initialized by the first position processing unit's absolute auxiliary value, allowing for independent and redundant position measurement without the need for duplicate detection units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two independent position detection units are provided to generate redundant position values, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the absolute position detection function into the incremental position processing unit. The incremental graduation track is used to generate both incremental position signals and absolute position values through initialization with an absolute auxiliary position value. This eliminates the need for a separate absolute position detection unit while maintaining redundant position measurement capability, thereby reducing device complexity without sacrificing reliability.
Solution Approach 2:
The incremental position processing unit is designed to perform multiple functions: it processes incremental position signals from the incremental graduation track and, when initialized with an absolute auxiliary position value from the first position processing unit, generates absolute position values. This multi-functionality allows a single unit to contribute to both incremental and absolute position measurement, reducing the overall number of components needed while ensuring reliable redundant position values.
2Reliability
If two independent position detection units are provided to generate redundant position values, then defect detection capability is improved, but cost increases
Solution Approach 1:
The patent combines the absolute position detection functionality into the existing incremental position processing unit. By using the incremental graduation track and initializing it with an absolute auxiliary position value, the system generates absolute position values without requiring a separate absolute position detection unit. This reduces component count and manufacturing cost while maintaining the capability to detect defects through comparison of position values from different processing paths.
3Measurement precision
If an absolute graduation track is provided parallel to an incremental graduation track to achieve high resolution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The incremental graduation track serves dual purposes: it generates incremental position signals for high-resolution relative position measurement and, when initialized with an absolute auxiliary position value, generates absolute position values. This eliminates the need for a separate absolute graduation track while maintaining high measurement precision through the phase angle detection of incremental signals and the absolute reference initialization.
Data Source
Figure 1~2
Figure 3a~3b
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AI summary
The device has a code carrier (1.2) that is provided with a first pitch track (1.21) and a second pitch track (1.22). The first and second detector arrays (2.22,2.23) are used for generating first and second position signals by scanning the pitch tracks in a measuring direction. The first and second position processing units are used for processing the first and second position signals to first and second absolute positions. An absolute auxiliary position value is initialized and is fed to the second position processing unit from the first position processing unit. An independent claim is included for a method for operating position measuring device.