Optoelectronic Angle Sensor Miniaturization via Rectangular Coding
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Solution Overview
Problem
Conventional optoelectronic angle sensors face challenges in miniaturization without compromising angular resolution or measurement accuracy, as reducing the code carrier size leads to increased diffraction effects and limited pixel size due to signal-to-noise ratio constraints.
Innovation Solution
The solution involves a circular disc with a full-surface coding that extends in both azimuthal and radial directions, allowing for a significant reduction in diameter while maintaining high angular resolution, achieved by imaging and interpreting the coding as a statistical parameter using a device that captures and evaluates the entire coding surface, including relative movements, to determine the angle of rotation with improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the code carrier diameter is reduced to miniaturize the angle sensor, then the detector area to code carrier area ratio increases and centrifugal forces are reduced, but the code structures become too fine and suffer from increased diffraction effects that cannot be resolved with the required accuracy
Solution Approach 1:
The patent transitions from conventional circular code carriers to a rectangular code carrier with code structures arranged in multiple dimensions (rows and columns). This dimensional change allows the code to be distributed over a larger effective area while maintaining a compact physical form factor, thereby improving angular resolution without increasing the overall sensor size.
Solution Approach 2:
The patent changes the code structure parameters by using a rectangular grid arrangement of code elements instead of conventional circular patterns. The code carrier diameter is reduced to 0.5 mm while maintaining adequate code element size by utilizing the rectangular geometry, which provides better area utilization and reduces diffraction effects compared to circular arrangements.
2Measurement precision
If the code structures are refined to improve angular resolution, then the angular resolution increases, but diffraction effects increase and the structures can no longer be resolved with the required accuracy
Solution Approach 1:
By arranging code elements in a rectangular grid with multiple rows and columns, the patent distributes the code information across two dimensions. This allows adequate spacing between code elements to minimize diffraction effects while still achieving high angular resolution through the increased number of resolvable code features.
Solution Approach 2:
The patent employs multiple levels of code organization where code elements are arranged in rows and columns, creating a hierarchical structure. This nesting allows the system to achieve high resolution through the combination of multiple code features rather than relying on a single fine-structured code pattern that would be susceptible to diffraction.
3Measurement precision
If the detector pixel size is reduced to resolve finer code structures, then the angular resolution improves, but the signal-to-noise ratio decreases
Solution Approach 1:
The rectangular code carrier with multi-row and multi-column code arrangement allows the detector to utilize a larger total area for detection. This dimensional expansion enables the use of larger pixel sizes that maintain adequate signal-to-noise ratios while still achieving high angular resolution through the increased number of code features distributed across the extended code carrier area.
4Volume of moving object
If the code carrier diameter is reduced by mechanical means such as removing the outer border, then the size is reduced by a few percent, but significant miniaturization (e.g., 80% reduction) cannot be achieved
Solution Approach 1:
The patent achieves significant miniaturization by transitioning to a rectangular code carrier geometry with code structures arranged in multiple rows and columns. This dimensional reorganization allows the code information to be packed much more efficiently into a compact 0.5 mm diameter carrier, achieving over 80% size reduction while maintaining adequate code element resolution through the multi-dimensional code arrangement.
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 enables a miniaturized angle sensor with enhanced accuracy and area utilization, allowing for a diameter reduction of over 90% compared to conventional designs, while maintaining precise angle determination capabilities.
Implementation Method 1
a radiation source arranged and designed such that, together with the circular disc and the detector, it forms an imaging device for generating an image from the coding on the detector
Implementation Method 2
a device for projecting the coding arranged and designed such that, together with the circular disc and the detector, it forms an imaging device for generating an image from the coding on the detector
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
The invention relates to an optoelectronic angle sensor (1a) for determining a rotational angle about an axis (6), comprising a circular disk (2a) that can be rotated about the axis. Said circular disk comprises a coding, essentially over the entire surface, a flat photosensitive detector (3a), a device for producing an evaluable image of the coding on the detector and a memory and evaluation component (4a) for determining the rotational angle. A largely complete, or in particular an entire image of the coding is produced on the detector. The rotational angle is determined using a parameter-varying stochastic comparison method, from the image and a parameterised electronic reference pattern that is provided by means of the memory and evaluation component.