Transparent Conductive Coating Shielding for Optical Position Detector
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Solution Overview
Problem
Existing optical position-measuring devices face challenges in effectively shielding against electrical interference fields, leading to erroneous position detection due to difficulties in producing and maintaining electrical contact with ground potential.
Innovation Solution
A compact and reliably shielded scanning unit is achieved by using a transparent, electrically insulating carrier with a scanning grating and a conductive cover plate that is easily connected to ground potential, featuring a transparent carrier with a detector arrangement and a conductive base body that shields electromagnetic fields on all sides, with a transparent, electrically conductive coating or lattice structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent, electrically conductive shielding body is used to shield the detector arrangement from electromagnetic interference, then shielding effectiveness is improved, but manufacturing complexity and difficulty of establishing electrical contact with ground potential increases
Solution Approach 1:
The shielding structure is divided into multiple segments: a base body with conductive material, a transparent carrier holding the detector arrangement, and a cover plate with conductive coating. These segmented components are easier to manufacture individually and assemble than a single complex shielding body, while maintaining effective electromagnetic shielding through the combined structure.
Solution Approach 2:
Conductive adhesive serves as an intermediary substance to establish electrical contact between the conductive elements (base body, cover plate) and ground potential. This intermediary simplifies the manufacturing process compared to direct mechanical or soldered connections, as the adhesive simultaneously provides mechanical bonding and electrical conductivity.
2Illumination intensity
If a transparent carrier with detector arrangement is used, then optical transparency is improved, but electrical insulation and shielding capability deteriorates
Solution Approach 1:
Different parts of the system have different electrical properties: the transparent carrier remains electrically insulating to maintain optical transparency, while the base body and cover plate are made conductive through embedded materials or coatings. This local differentiation allows the insulating carrier to transmit light while conductive elements provide electromagnetic shielding.
Solution Approach 2:
The shielding structure uses composite construction: a transparent insulating carrier (glass or plastic) combined with conductive elements (metal layers, conductive adhesives, conductive coatings). This composite approach allows simultaneous achievement of optical transparency from the carrier and electromagnetic shielding from the conductive components.
3Reliability
If electrical contact with ground potential is established through complex structures, then shielding reliability is improved, but production difficulty and time increase
Solution Approach 1:
Conductive adhesive is applied in advance to predetermined locations on the base body and cover plate during assembly. This preliminary application of conductive material ensures that electrical contact paths are established before final assembly, simplifying the manufacturing process and reducing production time compared to post-assembly electrical connection methods.
Solution Approach 2:
The conductive adhesive performs dual functions simultaneously: it provides mechanical bonding between components and establishes electrical contact with ground potential. This self-service capability eliminates the need for separate electrical connection steps, reducing production time while ensuring reliable shielding.
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 provides effective shielding against electromagnetic interference, ensuring accurate position detection while simplifying production and electrical contacting, thereby enhancing the reliability and compactness of the scanning unit.
Implementation Method 1
The cover plate (15) is provided with a shield (16) to shield the side that is still open... The shield 16 is arranged on the surface facing the first surface 10 of the transparent support 5
Implementation Method 2
the scanning unit 2 comprises a light source 4, the light of which strikes the scale 1, is modulated there by the measuring graduation 3 as a function of the position, and is reflected onto a detector arrangement 6
Implementation Method 3
The transparent carrier 5 has a scanning grating 7 which, in a known manner, consists of opaque areas and transparent areas arranged alternately next to one another. The scanning grating 7 serves to form a plurality of partial beams of rays which interact with the measuring graduation 3 of the scale 1
Data Source
Figure 1~2
AI summary
In an optical position measuring device, the detector assembly (6) is shielded against electromagnetic interference. A transparent, electrically conductive coating (16) on a cover plate (15) serves as the shielding. The cover plate (15) covers a recess (21) in a base body (20) in which a transparent carrier (5) with the detector assembly (6) is housed. The detector assembly (6) is located on the underside of the carrier (5), and the carrier (5) is in turn attached to the cover plate (15) at its upper side.