Position Measuring Device Free-Space Optical Coupling
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Solution Overview
Problem
High-precision position measuring devices face inaccuracies due to mechanical coupling between movable scanning units and stationary signal units, leading to potential tilting errors and increased structural size.
Innovation Solution
A position measuring device with a reflective scale and a scanning unit, where the scanning unit and signal unit are structurally separate and disposed in parallel planes, allowing beams to propagate freely without deflection, minimizing mechanical coupling and tilting sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If waveguides are used to connect the scanning unit and signal unit, then mechanical coupling is established, but this leads to tilting errors and reduced measurement precision
Solution Approach 1:
The patent extracts the optical beam transmission function from the mechanical waveguide structure. Instead of using physical waveguides that create mechanical coupling, the invention allows light beams to propagate freely through air space between the scanning unit and signal unit, eliminating the mechanical connection while maintaining optical functionality.
Solution Approach 2:
The patent replaces the mechanical waveguide system with an optical free-space propagation system. The mechanical coupling provided by waveguides is substituted by direct optical beam transmission through air, using optical elements (lenses, mirrors) to guide and focus the beams without physical connection between the scanning unit and signal unit.
2Ease of operation
If waveguides are used to connect the scanning unit and signal unit, then signal transmission is enabled, but the structural size increases and complexity increases
Solution Approach 1:
The patent removes the waveguide components from the system architecture. The signal transmission function is extracted from the mechanical waveguide structure and achieved through free-space optical propagation, simplifying the overall device structure by eliminating unnecessary mechanical connection elements.
Solution Approach 2:
The patent transitions from a mechanically coupled 3D structure (waveguides requiring physical space and alignment) to a free-space optical system where beams propagate through air. This dimensional reorganization allows the scanning unit and signal unit to be positioned independently without mechanical constraints, reducing structural complexity.
3Volume of moving object
If the scanning unit is made compact, then space is saved, but mechanical coupling to the stationary signal unit becomes more difficult to avoid
Solution Approach 1:
The patent replaces mechanical coupling systems with free-space optical beam transmission. This substitution allows the scanning unit to be compact without requiring mechanical connections to the signal unit, as the optical beams can traverse any distance in free space without physical attachment.
Solution Approach 2:
The patent segments the position measurement system into two independent units: a compact movable scanning unit and a stationary signal unit. The segmentation is maintained through free-space optical coupling rather than mechanical connection, allowing each unit to be optimized independently for size and function without compromising the other.
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 reduces errors from tilting and minimizes structural size, enabling high-precision position detection with reduced interference and increased robustness.
Implementation Method 1
The light source emits a focused beam that propagates freely in a direction to the scanning unit, wherein from the scanning unit along the direction to the signal unit a pair of interfering partial beams propagate freely
Implementation Method 2
from the scanning unit along the direction to the signal unit a pair of interfering partial beams propagate freely
Implementation Method 3
The scanning unit includes a retroreflector and a signal unit wherein the signal unit includes a light source and a detector arrangement
Data Source
AI summary
A position measuring device including a reflective scale and a scanning unit. The scanning unit includes a retroreflector and a signal unit wherein the signal unit includes a light source and a detector arrangement. The scanning unit and the signal unit are structurally separate from one another and are disposed in planes parallel to one another, and wherein the scanning unit is movable relative to the reflective scale in a measuring direction. The light source emits a beam that propagates freely in a direction to the scanning unit, wherein from the scanning unit along the direction to the signal unit a pair of interfering partial beams propagate freely and wherein between the signal unit and the scanning unit the partial beams propagate freely in a propagation direction that is oriented perpendicular to the planes.