Multi-turn Rotary Encoder Flexible Circuit Board Design

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Solution Overview

Problem

Multiturn encoders face challenges in achieving robust operating behavior against external influences while being economically viable, particularly in industrial applications where they need to measure rotational movements over multiple revolutions with high precision and reliability.

Innovation Solution

The design incorporates a multiturn encoder with a metal body constructed in multiple layers, featuring a first and second area for the circuit board, where the first area houses a detector and electronic components connected via conductor tracks, and the second area contains additional electronic components. This configuration includes a gear system with gear wheels, where the metal body provides mechanical support and can be made of ferromagnetic steel or aluminum, with a flexible circuit board and a curved connecting web, allowing for inductive, magnetic, or capacitive principles of operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid circuit board is used to mount detectors and electronic components, then mechanical stability is improved, but adaptability to different detector arrangements and economic production are worsened

Engineering Contradiction:
Improvemechanical stabilityVSAvoidadaptability to detector arrangements
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent employs a flexible circuit board instead of a rigid one, allowing the board to be bent and adapted to different detector arrangements while maintaining electrical connections. This flexibility enables the same circuit board design to accommodate various detector positions and types, improving adaptability without sacrificing mechanical stability when properly mounted.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The circuit board is designed with flexible regions that allow dynamic adaptation to different mounting configurations. The flexible nature enables the board to conform to different geometric arrangements of detectors and electronic components, making the encoder adaptable to various design requirements while maintaining structural integrity through proper mounting.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple separate components are used for detectors and electronic components, then functional independence is improved, but device complexity and manufacturing cost are worsened

Engineering Contradiction:
Improvefunctional independenceVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent integrates detectors and electronic components onto a single flexible circuit board, reducing the number of separate components and simplifying the overall device structure. This consolidation maintains functional independence of each component while reducing assembly complexity, mounting requirements, and manufacturing steps, thereby lowering production costs without compromising functionality.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If a multi-layer metal body is used to house the circuit board, then mechanical support and protection are improved, but manufacturing complexity are worsened

Engineering Contradiction:
Improvemechanical supportVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The metal body is constructed in multiple layers with specific regions designed to accommodate the flexible circuit board and its components. This segmentation allows each layer to serve a specific function - providing mechanical support, housing, or mounting surfaces - while maintaining relative simplicity in manufacturing each individual layer, thereby reducing overall manufacturing complexity despite the multi-layer structure.

Inventive Principle:
Principle #1Segmentation

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 design enhances the encoder's robustness and economic production by providing a stable, precise measurement of angular positions over multiple revolutions, with the metal body offering mechanical support and the flexible circuit board enabling efficient signal transmission, while being adaptable to various measurement principles.

Implementation Method 1

In the case of inductive sensors, excitation windings and detector windings are often applied in the form of conductor tracks on a common circuit board

Methodology Applied
Scientific EffectInductive principle: Electromagnetic Induction

Implementation Method 2

The multiturn encoder can be based on a magnetic principle, in which case the first detector for single-turn scanning can be designed in the form of one or more magnetoresistive elements or Hall elements

Methodology Applied
Scientific EffectMagnetic principle: Magnetic Field

Implementation Method 3

The invention also includes a multiturn encoder which is based on a capacitive principle

Methodology Applied
Scientific EffectCapacitive principle: Capacitance

Implementation Method 4

the rotational movements of the shaft to be measured are often transferred by reduction gears to the rotational movements of angle-coded gear wheels

Methodology Applied
Scientific EffectReduction gears: Gear

Implementation Method 5

electronic components which are electrically connected to the first detector, in particular through conductor tracks on the circuit board

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3534121B1Multi-turn rotary encoder
Publication Date: 2021.01.27 DR JOHANNES HEIDENHAIN GMBH
  • EP3534121B1 patent drawingFigure 1
  • EP3534121B1 patent drawingFigure 2
  • EP3534121B1 patent drawingFigure 3~4

AI summary

The invention relates to a multiturn rotary encoder comprising a gearbox (8), a metal body (2; 2'), and a printed circuit board (1). The printed circuit board (1) has a first region (1.1) in which a first detector (1.12) is arranged and a second region (1.2) in which electronic components (1.21) are arranged. The metal body (2; 2') has at least one recess (2.11, 2.21; 2.11', 2.21'), a first layer (2.1) with a first surface (S21), and a second layer (2.2, 2.2') with a second surface (S22). The first area (1.1) of the printed circuit board (1) is mounted on the first surface (S21) and the second area (1.2) of the printed circuit board (1) is mounted on the second surface (S22), such that the first area (1.1) is arranged in a first plane (E11) and the second area (1.2) in a second plane (E12). The gearbox (8) has at least one output-side gear wheel (8.1, 8.2; 8.2') which is arranged at least partially within the recess (2.11, 2.21; 2.11', 2.21') over its axial extent (h), wherein the recess (2.11, 2.21; 2.11', 2.21') is located between the first plane (E11) and the second plane (E12) with respect to the axial direction. (Figure 7).