Light Detection Circuit for Accurate Optical Recognition
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Solution Overview
Problem
Existing light detection circuits struggle to accurately recognize touch regions and fingerprint patterns under high ambient light conditions, as the intensity of ambient light leads to quick discharging of charges, making it difficult to distinguish between touch and non-touch regions or ridge and valley lines.
Innovation Solution
A light detection circuit is designed with a potential pull-up sub-circuit that connects the charge storage sub-circuit with a second power terminal when the reading node's potential decreases by a preset value, maintaining the potential and allowing continuous light current generation, and includes a resetting sub-circuit to reset the potential to the initial value, enabling accurate signal acquisition even under strong ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light detection circuit operates under high ambient light conditions, then the photoelectric conversion continues, but the charges discharge quickly making it difficult to distinguish touch regions
Solution Approach 1:
The circuit performs preliminary charge accumulation in the charge storage sub-circuit before signal readout. By pre-charging the storage node during the integration period, the circuit builds up sufficient charge signal before ambient light causes rapid discharge, enabling accurate touch detection even in high ambient light conditions
Solution Approach 2:
The charge storage sub-circuit acts as an intermediary between the photoelectric conversion element and the readout circuitry. It temporarily holds the accumulated charge, isolating the sensitive measurement from the rapid discharge caused by ambient light, and enabling controlled signal readout at the optimal moment
2Loss of information
If the reading node potential decreases due to charge discharge, then the signal changes reflect light intensity, but the potential continues to decrease making continuous detection difficult
Solution Approach 1:
The circuit employs periodic reset operations where the reading node potential is periodically restored to its initial level. This periodic resetting allows the photoelectric conversion to continuously accumulate charge over multiple integration periods, enabling sustained detection capability without permanent depletion of the signal dynamic range
Solution Approach 2:
The circuit discards the depleted charge state by resetting the reading node potential when it decreases below a threshold, and recovers the full dynamic range by restoring it to the initial potential. This discard-recover cycle enables continuous operation while maintaining full measurement capability across multiple detection periods
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 solution allows for accurate recognition of touch regions and fingerprint patterns by maintaining the potential of the reading node and enabling continuous light current generation, effectively distinguishing between touch and non-touch regions or ridge and valley lines even under high ambient light conditions.
Implementation Method 1
a photoelectric conversion sub-circuit, which has one end connected to the reading node, and the other end connected to the first power terminal
Data Source
AI summary
A light detection circuit, an electronic device, and an optical recognition method are provided. The light detection circuit includes a charge storage sub-circuit (10), a photoelectric conversion sub-circuit (30), a signal collection sub-circuit (40), and a potential pull-up sub-circuit (50). When a potential of a reading node (A) is decreased by a preset value, the potential pull-up sub-circuit (50) changes the potential of the reading node (A) to an initial potential. A photoelectric diode may continuously generate a light current under the action of light, so that the potential of the reading node (A) is decreased again. Even when the intensity of ambient light is high, a touch can be accurately recognized in an optical touch recognition circuit, and ridge lines and valley lines can be accurately recognized in an optical fingerprint recognition circuit.