Noise Filter Circuit Substrate With Segmented Ground Plane

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Solution Overview

Problem

Existing noise filter circuits require two grounds, which is impractical in limited spaces such as the indoor unit of an air conditioner, where space is constrained.

Innovation Solution

A circuit substrate with a single ground plane pattern connected to both the primary and secondary sides, divided by a cutout to prevent noise superimposition, allowing for efficient noise removal without requiring additional space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If two grounds are provided to prevent noise superimposition, then noise removal effectiveness is improved, but device area increases

Engineering Contradiction:

Improvenoise removal effectivenessVSAvoiddevice area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The ground plane pattern is divided into first and second ground patterns by a cutout portion. The first ground pattern is connected to the primary side terminal and the second ground pattern is connected to the secondary side terminal, preventing noise removed on the secondary side from being superimposed on the primary side through the ground plane. This segmentation achieves noise isolation without requiring two separate ground connections.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A cutout portion is introduced to extract or remove the problematic continuous ground plane connection between primary and secondary sides. By taking out this connecting portion, the patent prevents noise propagation paths while maintaining the integrity of both primary and secondary side ground references.

Inventive Principle:

Principle #2Taking out (Extraction)

2Area of stationary object

If a single ground plane is used to save space, then device area is reduced, but noise superimposition occurs

Engineering Contradiction:

Improvedevice areaVSAvoidnoise superimposition

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The single ground plane pattern is segmented into first and second ground patterns by introducing a cutout portion. This segmentation maintains the space-saving advantage of a single ground plane while preventing noise superimposition by electrically isolating the primary side ground from the secondary side ground.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cutout portion extracts the noise propagation path from the continuous ground plane. By removing this connecting portion, the patent prevents noise removed on the secondary side from being superimposed on the primary side, while maintaining the compact single ground plane structure.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP3176947B1Noise filter circuit substrate and method of manufacturing the same

Publication Date: 2019.07.03 MITSUBISHI HEAVY IND THERMAL SYST

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Figure 4A~4B

AI summary

Saving space and removing noise as much as possible can be achieved. Provided is a circuit substrate (1) including a single ground plane pattern (E1) and a common-mode choke coil (L1) that removes noise propagated from a power source (2). The ground plane pattern (E1) is connected to a first wire (4) connected to a primary side before the noise is removed by the common-mode choke coil (L1) and to a second wire (6) connected to a secondary side from which the noise is removed through the common-mode choke coil (L1), and the ground plane pattern (E1) is divided between a portion connected to the first wire (4) and a portion connected to the second wire (6).