Light Receiving Device Circuit Pattern for High S/N Ratio
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Solution Overview
Problem
Conventional light receiving devices using quantum-type infrared sensors face challenges in achieving a high signal-to-noise ratio due to the small difference between human body temperature and environmental temperature, leading to increased noise levels and the need for cooling, which complicates the design and increases size and power consumption.
Innovation Solution
A light receiving device with a circuit pattern featuring multiple light receiving parts and output terminals formed on the same substrate, where the difference between signals from these parts is directly output without the use of switching elements, utilizing PN or PIN junction photodiode structures to enhance the signal-to-noise ratio and reduce the number of output terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cooling is applied to increase output signal and S/N ratio, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent changes the operating temperature parameter from cooled to room temperature by using quantum-type infrared sensors with specific semiconductor materials (InSb, MCT) that maintain high sensitivity at room temperature, eliminating the need for cooling systems while preserving measurement precision
Solution Approach 2:
The patent extracts and removes the cooling system from the sensor design, using quantum-type sensors that inherently operate at room temperature, thereby simplifying the device structure and reducing power consumption while maintaining high S/N ratio through multi-stage series connection
2Measurement precision
If multiple light receiving parts are used to calculate difference values, then measurement precision is improved, but device complexity increases due to multiple output terminals and switching elements
Solution Approach 1:
The patent merges multiple light receiving parts (first, second, third, and fourth light receiving parts) onto a single substrate with integrated output terminals, combining their functions into a unified structure that reduces the number of separate components and simplifies the overall circuit design
Solution Approach 2:
The patent designs output terminals that serve multiple functions: they collect signals from multiple light receiving parts and enable both difference value calculation (for light intensity and motion detection) and summation value calculation (for approaching detection), eliminating the need for separate dedicated terminals for each function
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 configuration allows for high signal-to-noise ratio calculations from light receiving parts while minimizing the number of output terminals and eliminating the need for switching elements, thereby reducing the device's size and power consumption.
Implementation Method 1
an electron-hole pair generated by a photon of the infrared light in a depletion layer existing in the PN junction or the PIN junction is separated spatially along a gradient of a valence band and a conduction band to be accumulated, and as a result the p-type semiconductor is charged positively and the n-type semiconductor is charged negatively to generate an electromotive force in between
Implementation Method 2
By detecting this light, it is possible to detect a position or motion of a human body
Data Source
AI summary
The light receiving device of the present invention includes a circuit pattern including first and second light receiving parts and first and second output terminals, each of the first and second light receiving parts having a semiconductor layered part forming a photodiode structure having first and second conductivity type semiconductor layers, and first and second electrodes respectively connected to the first conductivity type semiconductor layer and the second conductivity type semiconductor layer, wherein the first electrodes of the first and second light receiving parts are connected to each other, the second electrode of the first light receiving part is connected to the first output terminal, the second electrode of the second light receiving part is connected to the second output terminal, and a difference between signals generated in the first and second light receiving parts are output between the first and second output terminals.