Encoder Scale Static Dissipation via Conductive Adhesive Grounding
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Solution Overview
Problem
Electromagnetic induction type linear encoders face operational failures due to static electricity accumulation in scale coils, which conventional ground patterns inadequately address, especially outside the grounded areas.
Innovation Solution
An encoder scale with an insulating substrate, a conductive adhesive layer connecting pattern layers, and an out-of-detection-range pattern grounded via a conductive member, including a conductive thin film and resin adhesive film with a conductive filler, ensures effective static electricity dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ground pattern is formed outside the scale coils to ground the ground pattern to a scale base, then static electricity generated in the encoder scale is let to go to the scale base, but the ground pattern is not sufficiently effective for parts other than where it is formed, causing operation failure when scale coils are charged with static electricity
Solution Approach 1:
The grounding structure is segmented into multiple functional layers: conductive adhesive layer forming ground patterns, conductive member layers providing additional grounding paths, and insulating protective layers. This segmentation allows each layer to contribute to overall grounding effectiveness without requiring a single complex grounding structure to cover the entire encoder scale surface.
Solution Approach 2:
The invention transitions from a two-dimensional ground pattern on the scale base to a multi-layered three-dimensional grounding structure. Conductive adhesive layers are applied between the scale base and scale coils, and additional conductive member layers are positioned at different heights, creating multiple grounding dimensions that effectively dissipate static electricity from all areas including scale coils.
2Reliability
If the scale coil itself is charged with static electricity, then operation failure or malfunction of the electromagnetic linear encoder may be caused, but conventional ground patterns cannot effectively discharge static electricity from scale coils
Solution Approach 1:
Conductive adhesive layers serve as intermediary elements between the scale base and scale coils. These adhesive layers contain conductive materials that provide a controlled path for static electricity to dissipate from the scale coils to the grounded scale base, preventing direct discharge that could cause malfunction while effectively removing accumulated static charge.
Solution Approach 2:
The invention changes the electrical conductivity parameter of the adhesive layer by incorporating conductive materials into the adhesive formulation. This transforms the adhesive from an insulating material to a semi-conductive or conductive material, enabling it to function as an effective grounding path while maintaining its adhesive properties for bonding the scale base to scale coils.
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
Stably resolves static electricity charging issues, preventing operation failures and enhancing the encoder's reliability by ensuring all pattern layers are electrically connected and grounded, thus preventing static discharge.
Implementation Method 1
the adhesive layer electrically connects all the pattern layers
Implementation Method 2
the out-of-detection-range pattern is grounded via a conductive member
Data Source
AI summary
An encoder scale, displaced relative to a detector head, includes: an insulating substrate; a conductive adhesive layer that is formed on the insulating substrate; and conductive pattern layers that are formed on the adhesive layer in a shape enabling the detector head to detect a position, wherein: the adhesive layer electrically connects all the pattern layers and includes an out-of-detection-range pattern that extends outward from a position detection range of the detector head; and the out-of-detection-range pattern is grounded via a conductive member.