Miniature Infrared Thermopile Sensor for TWS Earphones
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Solution Overview
Problem
Traditional thermopile sensors are too large to be integrated into true wireless stereo earphones and are not suitable for immediate plug-and-play use, and they struggle with accuracy due to acute changes in ambient temperature.
Innovation Solution
A miniature infrared thermopile sensor with a stacked 3D package, including an infrared sensing chip, a silicon cover with an infrared Fresnel lens, and a microcontroller chip, which uses dual thermopile sensing elements for accurate temperature measurement and compensation, reducing the sensor's volume and thermal disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional TO-46 type metal package thermopile sensor is used, then the sensor can measure temperature, but the size is too large to be integrated within TWS earphone
Solution Approach 1:
The patent transitions from traditional 2D planar packaging to a 3D stacked architecture where the infrared sensing chip, silicon cover with Fresnel lens, and microcontroller chip are vertically stacked and interconnected through TSVs. This dimensional change enables compact integration while maintaining functional performance
Solution Approach 2:
The patent implements nested integration by placing the infrared sensing chip within a silicon cover that contains the Fresnel lens, and further integrating the microcontroller chip with TSV connections. The compact SMD package encapsulates the entire stacked structure, creating a nested configuration that minimizes overall volume
2Loss of time
If traditional ear thermometer is used, then temperature measurement is possible, but it requires stable environment for at least 30 minutes before measurement which is not suitable for plug and play
Solution Approach 1:
The patent performs preliminary thermal stabilization by pre-heating the infrared sensing chip and associated components to the operating temperature range before actual temperature measurement begins. This preliminary thermal conditioning eliminates the need for extended warm-up periods during actual use
Solution Approach 2:
The patent dynamically adjusts measurement parameters and compensation algorithms based on real-time thermal conditions. By monitoring temperature drift and adapting the measurement parameters accordingly, the system maintains accuracy without requiring extended stabilization periods
3Measurement precision
If non-contact infrared thermopile sensor is used in wireless earphone, then temperature measurement can be performed, but acute change of ambient temperature affects measurement accuracy
Solution Approach 1:
The patent implements feedback-based temperature compensation by continuously monitoring the ambient temperature through the microcontroller's internal sensors and the infrared sensing chip's temperature readings. The system dynamically adjusts measurement parameters and applies compensation algorithms to maintain accuracy across varying ambient conditions
Solution Approach 2:
The patent extracts and isolates the infrared sensing chip in a separate silicon cover with Fresnel lens, thermally decoupling it from the microcontroller chip and other heat-generating components. This physical separation reduces thermal interference from the microcontroller while enabling independent temperature stabilization of the sensing element
4Volume of moving object
If SMD packaged thermopile sensor is used, then the sensor can be mounted on PCB, but the size of 3×3×1 mm³ is still too big to fit in TWS earphone
Solution Approach 1:
The patent reduces the sensor footprint by transitioning from 2D planar mounting to 3D vertical stacking. The infrared sensing chip, silicon cover, and microcontroller are stacked vertically and connected through TSVs, reducing the lateral footprint while maintaining functional integration
Solution Approach 2:
The patent merges multiple functions into a single integrated package: the infrared sensing chip for temperature detection, the silicon cover with Fresnel lens for optical focusing, and the microcontroller chip for signal processing and compensation. This functional integration eliminates the need for separate components and reduces overall volume
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 solution enables accurate temperature measurement in true wireless stereo earphones, even under acute ambient temperature changes, by using a compact design and dual thermopile sensing elements to compensate for package structure influences, ensuring reliable and immediate temperature readings.
Implementation Method 1
The first thermopile sensing element is disposed on one of the membrane structures and generates an object corresponding temperature signal
Implementation Method 2
The second thermopile sensing element is disposed on another one of the membrane structures and adjacent to the first thermopile sensing element, and generates a compensation temperature signal
Implementation Method 3
The silicon cover is bonded to the infrared sensing chip by a wafer-level bonding, and includes an infrared Fresnel lens focusing a thermal radiation of the object to the first thermopile sensing element
Implementation Method 4
The ambient temperature sensing element generates a calibrated ambient temperature information
Data Source
AI summary
An infrared thermopile sensor includes a silicon cover having an infrared lens, an infrared sensing chip having duo-thermopile sensing elements, and a microcontroller chip calculating a temperature of an object. The components are in a stacked 3D package to decrease the size of the infrared thermopile sensor. The infrared sensing chip and the microcontroller chip have metal layers to shield the thermal radiation. To measure object temperature accurately under acute change in environmental temperature, this disclosure uses the duo-thermopile sensing elements, that one is the active unit for measuring the object temperature and another one is the dummy unit for compensating the effect from the package structure.