Incremental Encoder Scale with Segmented Scattering Areas
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Solution Overview
Problem
Existing incremental encoders have low contrast sensor signals and limited interpolability, making it difficult to accurately detect position changes due to the small difference between scattering and mirror areas, leading to inadequate recognition of individual scattering areas and poor displacement recording.
Innovation Solution
A material measure with alternating scattering and mirror areas, where the scattering areas have at least two line-like depressions that are perpendicular to the incremental track and have a width less than half the pitch, and are formed by overlapping round depressions to enhance diffused light reflection and reduce crosstalk, with the width of the scattering areas optimized between 10% to 50% of the pitch for improved contrast and interpolability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of scattering areas is increased to improve signal detection, then the sensor signal contrast decreases due to increased crosstalk between adjacent scattering areas
Solution Approach 1:
The scattering areas are segmented into multiple line-like depressions (at least two) arranged perpendicular to the incremental track direction. This segmentation reduces the effective width of each scattering area in the longitudinal direction while maintaining sufficient transverse coverage for light scattering, thereby reducing crosstalk between adjacent scattering areas and improving signal contrast for position measurement.
Solution Approach 2:
The invention applies different geometric configurations to different parts of the scattering areas. The line-like depressions are arranged with specific spacing and orientation (perpendicular to the incremental track) to optimize light scattering properties locally, ensuring sufficient scattering for detection while minimizing interference with adjacent areas, thus resolving the contradiction between detection reliability and measurement precision.
2Measurement precision
If the width of scattering areas is decreased to reduce crosstalk and improve contrast, then the interpolability of the sensor signal deteriorates
Solution Approach 1:
The invention transitions from considering only the longitudinal width of scattering areas to utilizing the transverse dimension by creating line-like depressions perpendicular to the incremental track. This dimensional change allows the scattering areas to have small longitudinal width (reducing crosstalk and improving contrast) while maintaining sufficient transverse extent (preserving interpolability) for accurate position determination between marks.
3Ease of manufacture
If traditional line element structures are used for scattering areas, then manufacturing is simplified, but the sensor signal contrast remains low due to diffraction pattern dominance
Solution Approach 1:
The invention changes the geometric parameters of the scattering areas from traditional fine line elements (width 0.5-1.5 μm) to coarser line-like depressions created by overlapping round depressions. This parameter change maintains manufacturing simplicity through laser processing while significantly increasing the contrast of the sensor signal by reducing diffraction effects and enhancing direct light scattering, thereby resolving the contradiction between ease of manufacture and measurement precision.
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
The solution significantly increases the contrast of the sensor signal and improves interpolability by ensuring that diffusely reflected light is primarily imaged onto the sensor, allowing for more accurate position determination and reliable sensor signal generation.
Implementation Method 1
The scattering areas of the at least one incremental track each have a plurality of essentially round depressions, which are designed to diffusely reflect incident light
Implementation Method 2
the mirror areas of the at least one incremental track have a substantially smooth surface, which is designed to reflect incident light in a specular manner
Implementation Method 3
each scattering area has at least two line-like depressions, which extend essentially perpendicular to the longitudinal direction of the incremental track and are arranged one behind the other in a row in the longitudinal direction of the incremental track
Data Source
Figure 1a~1b
Figure 1c
Figure 1d~1e
AI summary
The present invention relates to a measurement element (10) for incremental encoders, wherein the measurement element (10) has an incremental track (20) with scattering regions (23) and reflective regions (24) alternately arranged in the longitudinal direction (x). Each scattering region (23) comprises at least two linear recesses (26-1, 26-2, 26-3, 26-4, 26-5), which extend substantially perpendicular to the longitudinal direction (x) of the incremental track and are arranged consecutively in a series in the longitudinal direction (x) of the incremental track (20) and are additionally formed to diffusely reflect incident light. The reflective regions (24) of the incremental track (20) have in contrast a substantially smooth surface, which is additionally formed to specularly reflect incident light. In addition, the incremental track (20) further comprises a pitch (P), which results from the addition of the width (B23) of one of the scattering regions (23) and the width (B24) of one of the reflective regions (24). In order to optimize the contrast of the radiation scattered by the measurement element, the scattering regions (23) comprise, in the longitudinal direction (x) of the incremental track (20), a width (B23), which is smaller than half the pitch (P), wherein each respective pair of the linear recesses (26-1, 26-2, 26-3, 26-4, 26-5) of a scattering region (23) are arranged on opposing outer sides (As1, As2) of the scattering region (23) and delimit the width (B23) of the one scattering region (23) in the longitudinal direction (x) of the incremental track (20).