Rotatable Polarizing Filter Alignment in Optoelectronic Sensors
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Solution Overview
Problem
Existing optoelectronic sensors face alignment accuracy issues with polarizing filters due to errors in manufacturing and assembly, leading to reduced cancellation capacity and increased complexity in injection molding tools, limiting flexibility and accuracy in the assembly process.
Innovation Solution
The polarizing filters are aligned by rotating the filter holder to optimize the extinction ratio, allowing for fixation without high accuracy requirements for reference surfaces, and can be manufactured in various sizes or designs for use in different sensor systems, reducing alignment errors and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polarizing filters are fixed in the optics carrier with high precision requirements, then alignment accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The filter carrier is designed to be rotatable relative to the optics carrier, allowing dynamic adjustment of the polarizing filter orientation. This replaces the need for complex precision fixtures in injection molding with a simple rotational mechanism that can be adjusted and fixed at the optimal position, thereby improving alignment accuracy without increasing manufacturing tool complexity.
Solution Approach 2:
The system is divided into separate functional modules: the optics carrier and the filter carrier. The filter carrier can be independently manufactured and then attached to the optics carrier, allowing each component to be optimized separately. This segmentation eliminates the need for complex multi-slide injection molding tools while maintaining alignment accuracy through the rotatable connection.
2Manufacturing precision
If polarizing filters are punched out in pairs with close tolerances, then alignment error is reduced, but production time increases
Solution Approach 1:
The polarizing filters are pre-mounted on the rotatable filter carrier in a convenient orientation during the punching process. The actual alignment is then achieved through rotation of the entire filter carrier rather than requiring precise positioning during the punching operation itself. This separates the punching operation from the alignment operation, allowing each to be optimized independently.
Solution Approach 2:
The rotatable filter carrier serves as both the mounting structure and the alignment mechanism. By rotating the filter carrier, the system self-aligns the polarizing filters without requiring external alignment tools or complex multi-step assembly processes, thereby reducing production time while maintaining precision.
3Ease of manufacture
If the filter carrier is fixed in position, then assembly simplicity is improved, but alignment flexibility is reduced
Solution Approach 1:
The filter carrier is designed with rotational freedom relative to the optics carrier, providing alignment flexibility. Once the optimal position is found, the filter carrier can be fixed in place, combining the benefits of flexibility during assembly with simplicity during operation. This dynamic design allows the system to adapt to different alignment requirements while maintaining a simple fixed structure during normal use.
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 reduces alignment errors, simplifies the manufacturing process, and allows for easier assembly automation, resulting in improved alignment accuracy and cost-effective production of optoelectronic sensors with reduced complexity in injection molding tools.
Implementation Method 1
Polarized light is used to distinguish whether the light reaches the light receiver from the retroreflector and not from an undesired reflection. A first polarizing filter is arranged after the light transmitter or light transmitters. A second polarizing filter is arranged in front of the light receiver. The polarizing filters are rotated at an angle of 90° to one another, since the light at the retro-reflector is given a 90° polarization rotation.
Data Source
Figure 1~2
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AI summary
Optoelectronic sensor and method for detecting objects (2) with at least one light emitter (3) and at least one light receiver (4) arranged such that light from the light emitters (3) is directed onto a transmitting path (6) to a retroreflector (7) and onto a receiving path (8) back to the light receiver (4), wherein the light emitters (3) and light receivers (4) have a common optic (9) or separate optics (9) for focusing the light onto a light beam according to the autocollimation principle, or each is assigned an optic (9) located close to each other according to the double-eye principle, wherein the optoelectronic sensor (1) is configured to direct the light from the light emitters (3) to the transmitting path (6) via a first polarizing filter (10) and the reflected light from the receiving path (8) to the light receiver (4) via a second polarizing filter (11), and wherein a control and evaluation unit (12) is configured toto recognize an interruption of the light beam as the detection of an object (2), wherein the first polarizing filter (10) or the second polarizing filter (11) is mounted on a filter carrier (13) so as to be rotatable about an optical longitudinal axis in an optical carrier (15), and the other second polarizing filter (11) or first polarizing filter (10) is fixed in position and the first polarizing filter (10) or the second polarizing filter can be fixed at an angle of 90° to the other second polarizing filter (11) or first polarizing filter (10).