Optical Encoder Waveguide Shielding Electromagnetic Compatibility
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Solution Overview
Problem
Optical encoders face challenges in achieving robust electromagnetic compatibility due to the interruption of shielding screens when moving parts are involved, leading to potential electromagnetic interference.
Innovation Solution
An optical encoder design that incorporates a continuous transparent electrical shielding screen and an optical waveguide between the moving part and the sensor, along with additional features like dual sensors and distinct wavelength emitters, to ensure electromagnetic isolation and improved signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous shielding screen is used to protect against electromagnetic interference, then electromagnetic compatibility is improved, but the moving part cannot pass through the shielding screen
Solution Approach 1:
An optical waveguide acts as an intermediary between the moving part and the sensor, allowing optical signals to pass through while maintaining electromagnetic shielding. The waveguide transmits light from the emitter to the sensor without requiring physical openings in the shielding screen, thus preserving both electromagnetic compatibility and moving part operation.
2Ease of operation
If the shielding screen is interrupted to allow passage of moving parts, then ease of operation is improved, but electromagnetic compatibility deteriorates
Solution Approach 1:
The optical waveguide serves as a mediator that carries optical signals through the shielding structure without creating electromagnetic openings. This allows the shielding screen to remain continuous for electromagnetic protection while the optical intermediary enables the moving part to function.
3Measurement precision
If an optical waveguide is used to transmit light, then signal transmission is improved, but the device complexity increases
Solution Approach 1:
The optical waveguide performs multiple functions: it transmits optical signals from the emitter to the sensor, maintains electromagnetic shielding integrity, and provides a compact integration structure. This multi-functionality justifies the added complexity by delivering multiple benefits from a single component.
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
Enhances electromagnetic compatibility by maintaining shielding integrity while allowing the optical encoder to function effectively, improving signal-to-noise ratio and providing redundancy and feedback mechanisms.
Implementation Method 1
the light radiation being totally reflected between the first face and the second face
Implementation Method 2
the first face comprises a first altered zone configured so that part of the light radiation leaves the optical waveguide through the altered zone in the direction of the moving part
Implementation Method 3
the electrical shielding screen being transparent to light radiation
Data Source
Figure 1~2
Figure 3a~3d
Figure 4
AI summary
The invention relates to an optical encoder for which improved robustness is sought. In the optical encoder, a sensor (17, 35) sensitive to light emitted by a light emitter (16) is arranged to detect light reflected by the diffusing area of a moving part (11). Between the moving part and the sensor is a planar optical waveguide (20) in which the light emitter emits said light and which has two external faces (22, 23), the light being totally reflected between these two faces. The moving part is located on one side (22) of the two faces, the sensor on the other side (23). The first face (22) includes a first altered area (30, 36) configured so that a portion of the light exits the optical waveguide towards the moving part. The optical waveguide is traversed by the light reflected by the diffusing area.