Photodiode Light-Receiving Area Compensation for Biometric Sensor Uniformity
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Solution Overview
Problem
Optical sensors used for detecting fingerprint and vein patterns face accuracy issues due to variations in light reception caused by differences in distance between the light source and photodiodes, leading to inconsistent detection sensitivity.
Innovation Solution
A detection device is designed with a configuration of photodiodes having varying light-receiving areas based on their distance from the light source, where photodiodes farther from the light source have larger light-receiving areas and those closer have smaller areas, to maintain consistent detection sensitivity across the detection area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If photodiodes are arranged at different distances from the light source, then the detection area can be expanded, but the light reception amount varies causing inconsistent detection sensitivity
Solution Approach 1:
The patent applies local quality by making the light-receiving area of each photodiode dependent on its distance from the light source. Specifically, photodiodes farther from the light source are designed with larger light-receiving areas, while those closer have smaller areas. This localized adjustment of photodiode geometry compensates for the inverse-square law of light propagation, ensuring uniform detection sensitivity across the entire detection area.
2Measurement precision
If photodiodes closer to the light source are used, then detection sensitivity is high, but light reception becomes excessive causing detection errors
Solution Approach 1:
The patent addresses excessive light reception by locally adjusting the light-receiving area of photodiodes based on their position. Photodiodes closer to the light source are designed with smaller light-receiving areas, which reduces the total light flux they receive and prevents saturation or detection errors caused by excessive light input.
3Area of stationary object
If photodiodes farther from the light source are used, then detection area is expanded, but light reception becomes insufficient reducing detection accuracy
Solution Approach 1:
The patent compensates for insufficient light reception by designing photodiodes farther from the light source with larger light-receiving areas. This geometric adjustment increases the total light flux captured by these photodiodes, ensuring they receive sufficient light for accurate detection despite their greater distance from the light source.
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 ensures that all photodiodes receive sufficient light for accurate biometric information detection, reducing variations in detection sensitivity and preventing excessive light reception, thereby enhancing the overall accuracy of the detection process.
Implementation Method 1
Light emitted from a light source is scattered and reflected by an object to be detected and enters each of the photodiodes. Thus, the photodiodes detect biometric information on the object to be detected.
Data Source
AI summary
According to an aspect, a detection device includes: a light source configured to emit light to an object to be detected; a plurality of photodiodes that each include a sensor electrode and an organic semiconductor layer and are arranged in a detection area; and one or a plurality of detection circuits coupled to the photodiodes. The photodiodes includes a first photodiode and a second photodiode that has a shorter distance from the light source than that of the first photodiode. A light-receiving area of the first photodiode is larger than a light-receiving area of the second photodiode.