Rigid-Flex PCB Layout for Wearable Slot Antenna Isolation
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Solution Overview
Problem
The presence of a metal frame in wearable electronic devices can affect antenna performance due to the proximity of electronic circuits, which are often located adjacent to the metal frame, interfering with wireless signal transmission and reception.
Innovation Solution
Incorporation of a rigid flexible printed circuit board with a rigid portion between the metal frame and a bracket, featuring a non-conductive portion in a fill-cut region to enhance antenna performance by radiating signals through a slot antenna formed between the metal frame and display panel, and conductive traces that extend from the rigid portion to improve signal radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a printed circuit board is disposed adjacent to the metal frame, then electronic circuits can be integrated for obtaining biometric and acoustic information, but the antenna performance is degraded due to interference with wireless signal transmission and reception
Solution Approach 1:
The rigid flexible printed circuit board is divided into a first portion under the electronic circuitry and a second portion extending toward the display. This segmentation allows the first portion to support electronic circuits while the second portion (with non-conductive region) minimizes interference with the slot antenna formed between the metal frame and display, thus resolving the contradiction between circuit integration and antenna performance.
Solution Approach 2:
A non-conductive region is created in the second portion of the rigid flexible printed circuit board, specifically in the area adjacent to the slot antenna. This local modification makes the PCB non-conductive in the critical region while maintaining conductivity where electronic circuits are needed, thereby allowing both circuit integration and optimal antenna performance.
2Adaptability or versatility
If conductive traces are present in the printed circuit board adjacent to the slot antenna, then electronic circuits can function, but the radiation efficiency of the slot antenna is reduced
Solution Approach 1:
The PCB is segmented into conductive and non-conductive regions. The first portion contains conductive traces for electronic circuit functionality, while the second portion features a non-conductive region that eliminates trace interference with the slot antenna, thereby maintaining both circuit functionality and radiation efficiency.
Solution Approach 2:
The PCB exhibits different electrical properties in different regions: conductive where electronic circuits are located and non-conductive where the slot antenna radiates. This local quality differentiation allows electronic circuits to function while minimizing energy loss from trace interference with the antenna.
3Device complexity
If the printed circuit board extends close to the display, then device integration is improved, but the slot antenna radiation area is reduced
Solution Approach 1:
The rigid flexible PCB is segmented such that the second portion extends toward the display for integration purposes, but includes a non-conductive region that effectively increases the slot antenna radiation area by preventing conductive interference, thus resolving the contradiction between integration and radiation area.
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 the performance of slot antennas by minimizing interference from the metal frame, thereby improving wireless signal transmission and reception in wearable electronic devices.
Implementation Method 1
the second portion includes a non-conductive portion arranged with respect to a slot between the metal frame and a portion of the display, the slot used to radiate a signal to an external electronic device
Data Source
AI summary
A wearable electronic device is provided. The wearable electronic device includes a housing including a metal frame, a display within the housing, a bracket within the housing, including a side surface facing an inner surface of the metal frame, a rigid flexible printed circuit board including a rigid portion located between the inner surface of the metal frame and the side surface of the bracket, and an electronic circuitry on the rigid portion, wherein the rigid portion includes a first portion under the electronic circuitry, and a second portion extending from a portion of the first portion toward the display and disposed on the side surface of the bracket so that the rigid portion is supported by the bracket, and wherein the second portion includes a non-conductive portion arranged with respect to a slot between the metal frame and a portion of the display, the slot used to radiate a signal to an external electronic device.