Fingerprint Sensing Circuit With Anode Voltage Control Under Strong Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical fingerprint identification systems face challenges in strong ambient light conditions, where photodiodes become saturated, leading to insufficient contrast and unclear fingerprint valley and ridge information due to non-linear response, preventing valid fingerprint collection.
Innovation Solution
A circuit with a voltage adjustment mechanism that connects a photodiode to a voltage adjustment circuit and a signal output circuit, allowing the photodiode to operate in a linear region by adjusting the anode voltage, thereby enlarging the dynamic range and ensuring valid fingerprint identification under strong ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the photodiode operates in strong ambient light conditions, then the fingerprint identification system can function in various environments, but the photodiode becomes saturated and enters a non-linear response region, causing insufficient contrast and unclear fingerprint information
Solution Approach 1:
The patent applies dynamics by making the anode voltage adjustable rather than fixed. The voltage adjustment circuit dynamically changes the anode voltage of the photodiode based on ambient light conditions, enabling the photodiode to operate in the linear response region even under strong ambient light, thus maintaining measurement precision while preserving environmental adaptability
Solution Approach 2:
The patent changes the electrical parameter (anode voltage) of the photodiode to resolve the contradiction. By adjusting the anode voltage through the voltage adjustment circuit, the photodiode's operating point is shifted from the saturated non-linear region back to the linear region, ensuring accurate fingerprint signal detection while maintaining the ability to operate in various lighting environments
2Device complexity
If the photodiode operates without voltage adjustment, then the circuit structure remains simple, but the photodiode enters saturation in strong light, producing non-linear response and losing fingerprint detail information
Solution Approach 1:
The patent applies preliminary action by adjusting the anode voltage before the photodiode detects the fingerprint signal. The voltage adjustment circuit pre-configures the photodiode's operating point to ensure it remains in the linear response region, preventing information loss at the valley and ridge transitions before detection occurs
Solution Approach 2:
The voltage adjustment circuit acts as an intermediary between the power supply and the photodiode. It mediates the voltage delivery to the photodiode, ensuring the photodiode receives the appropriate anode voltage to maintain linear operation, thereby preserving fingerprint information while managing the trade-off with circuit complexity
3Ease of operation
If the anode voltage is fixed, then the circuit is easier to control, but the photodiode cannot maintain linear response under varying light conditions, reducing identification accuracy
Solution Approach 1:
The patent applies self-service by enabling the voltage adjustment circuit to automatically adjust the anode voltage based on the operating conditions. The system self-regulates the photodiode's voltage to maintain linear operation without requiring manual intervention, thus preserving ease of operation while improving reliability through adaptive voltage control
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
Enables accurate fingerprint identification by changing the photodiode's working area from a saturated to a linear region, enhancing the contrast ratio and clarity of fingerprint data even in strong light environments.
Implementation Method 1
a photodiode (PIN)... the photodiode to work in a linear region... amplify and output a signal output by the photodiode
Data Source
AI summary
The present disclosure relates to a circuit for fingerprint identification and a driving method thereof, a display panel, and a display device. The circuit for fingerprint identification of the present disclosure includes a voltage adjustment circuit, a photodiode, and a signal output circuit; wherein the voltage adjustment circuit is electrically connected with an anode of the photodiode, and the signal output circuit is electrically connected with a cathode of the photodiode; the voltage adjustment circuit is configured to adjust an anode voltage input to the photodiode to enable the photodiode to work in a linear region; and the signal output circuit is configured to amplify and output a signal output by the photodiode.