Photodiode Detection Circuit Timing for Inrush Current Accuracy
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Solution Overview
Problem
Optical sensors using organic photodiodes (OPDs) face challenges in improving detection accuracy due to issues with parasitic capacitance and unintended capacitive coupling, which affect the reliability of biometric information detection.
Innovation Solution
A detection device with a photodiode configuration that includes a shield layer to reduce parasitic capacitance and a detection circuit that measures current output after a predetermined period, excluding initial inrush currents to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the detection circuit measures current immediately after the switch is turned on, then the measurement speed is fast, but the detection accuracy deteriorates due to inrush currents
Solution Approach 1:
The detection circuit performs preliminary actions by measuring the current multiple times before the formal measurement phase. These preliminary measurements capture the inrush current behavior, allowing the system to establish a baseline and exclude these initial readings from the final detection result, thereby preventing inrush currents from affecting accuracy
2Measurement precision
If multiple measurements are performed to improve accuracy, then the detection accuracy is improved, but the measurement time increases
Solution Approach 1:
The detection circuit employs periodic action by performing measurements in distinct phases: preliminary measurements at regular intervals before the formal measurement, and then formal measurements after the predetermined period. This structured periodic approach ensures adequate sampling to capture inrush current behavior while maintaining efficient timing to minimize total measurement duration
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 proposed configuration reduces errors in sensor values by minimizing the impact of inrush currents, thereby enhancing the detection accuracy and reliability of biometric information.
Implementation Method 1
a photodiode; and a detection circuit that is coupled to an anode or a cathode of the photodiode via a switch and is configured to output a sensor value corresponding to a current output from the photodiode
Data Source
AI summary
According to an aspect, a detection device includes: a photodiode; and a detection circuit that is coupled to an anode or a cathode of the photodiode via a switch and is configured to output a sensor value corresponding to a current output from the photodiode. The detection circuit is configured to measure the current output from the photodiode and output the sensor value, after a lapse of a predetermined period from a first time point at which the switch is turned on.