TOF Sensor Shielding Structure for High-Power EMI Control
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Solution Overview
Problem
TOF sensor modules in electronic devices are vulnerable to electromagnetic interference (EMI) due to high TX power operation, affecting both external and internal electrical structures, leading to performance degradation.
Innovation Solution
A noise shielding structure is applied to the distance detection sensor module, comprising a substrate with a light emitting unit, light receiving unit, control circuit, and ground layer, surrounded by multiple shield cans and shielding plates, connected to the ground layer to minimize EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light emitting unit operates at high TX power to improve distance detection accuracy, then the detection precision is improved, but electromagnetic interference is generated that affects external and internal electronic devices
Solution Approach 1:
The patent employs multiple nested shield cans of different sizes (first shield can, second shield can, third shield can) that are arranged concentrically around the light emitting unit. Each shield can is positioned at different depths and dimensions, creating a multi-layered nested structure that progressively contains and attenuates electromagnetic interference while allowing the high power operation to continue for accurate distance detection
Solution Approach 2:
The shield cans act as intermediary structures between the light emitting unit and the surrounding electronic devices. These conductive shield cans, connected to ground, serve as mediators that intercept and redirect electromagnetic fields, preventing direct interference with external devices while allowing the high power TX operation to maintain detection precision
2Length of moving object
If the light emitting unit operates at high TX power to improve distance detection range, then the detection range is extended, but electromagnetic interference affects the radiating performance of internal antennas
Solution Approach 1:
The nested arrangement of multiple shield cans creates progressively deeper containment zones for electromagnetic interference. The first shield can provides initial containment, the second shield can extends the containment depth, and the third shield can provides final containment, allowing the light emitting unit to operate at high power for extended detection range while protecting internal antenna performance through layered shielding
Solution Approach 2:
The shield cans are strategically positioned at different locations and depths around the light emitting unit, creating localized shielding zones. Each shield can is configured with specific dimensions and positions (first shield can at first depth, second shield can at second depth, third shield can at third depth) to target specific interference pathways, allowing high power operation for extended range while locally protecting antenna regions from electromagnetic interference
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
The noise shielding structure effectively reduces electromagnetic interference, preventing performance deterioration of nearby and internal electronic devices and structures.
Implementation Method 1
a first shield can disposed on the module housing and electrically connected to the ground layer of the substrate; and a second shield can disposed on the first shield can surrounding at least a portion of the light emitting unit exposed through the first shield can
Data Source
AI summary
According to various embodiments, an electronic apparatus may comprise: a housing including a front cover, a rear cover facing a direction opposite a direction of the front cover, and a side frame surrounding a space between the front cover and the rear cover; and a distance detection sensor module configured to detect a distance to an external object through the front cover from inside the space, wherein the distance detection sensor module may include: a substrate including a light emitting unit, a light receiving unit, a control circuit, and a ground layer; a module housing disposed on the substrate; a first shield can disposed in the module housing and electrically connected to the ground layer of the substrate; and a second shield can surrounding at least a portion of the light emitting unit disposed in the first shield can and exposed through the first shield can, and in contact with at least a portion of the first shield can.