Optical Detection Crosstalk Elimination via Periodic LED Activation
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Solution Overview
Problem
In high-resolution optical sensing systems, closely packed LEDs and photodiodes experience significant interference, leading to false detections and reduced sensing resolution due to the capture of radiant power from nearby LEDs, which is not tolerated in high-accuracy applications.
Innovation Solution
The optical sensing system addresses this by grouping detection units into zones and adjusting sensing durations, ensuring that LEDs are not turned on simultaneously to minimize interference, and using control signals to manage the timing of LED activation, thereby reducing both interference from nearby LEDs and ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple pairs of LEDs and photodiodes are placed close to each other to form a sensing network, then detection resolution and accuracy are improved, but photodiodes capture radiant power from nearby LEDs causing false detection
Solution Approach 1:
The patent implements periodic action by sequentially activating LEDs in different time slots rather than simultaneously. Each LED is turned on for a specific duration, and the system cycles through multiple LEDs in sequence. This temporal separation ensures that when one LED is active, its photodiode is the only one receiving significant radiant power, eliminating interference from nearby LEDs while maintaining close spacing for high resolution.
Solution Approach 2:
The patent applies preliminary action by using a controller to pre-determine and coordinate the activation timing of each LED and photodiode pair before actual detection occurs. The system establishes a predetermined sequence and timing schedule in advance, ensuring that photodiodes are ready to detect only from their paired LEDs at the appropriate moment, preventing false detections before they can occur.
2Speed
If LEDs are activated simultaneously to improve sensing speed, then response time is reduced, but interfering radiant power causes false detection
Solution Approach 1:
The system achieves periodic action by cycling through LED activation in sequential time slots. Each LED is activated for a predetermined duration, then the system transitions to the next LED. This periodic sequence maintains sensing speed by continuously monitoring all photodiodes while ensuring that only one LED is active at any given moment, preventing interference-induced false detections.
Solution Approach 2:
The patent implements dynamics by making the LED activation pattern adaptable rather than static. The controller dynamically adjusts the timing and duration of LED activation based on system requirements. This dynamic control allows the system to optimize between sensing speed and interference avoidance by adjusting activation parameters in real-time based on operational context.
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 approach significantly enhances detection accuracy and reduces power consumption by eliminating crosstalk between closely packed optical detection units, maintaining a low interference level and improving the overall sensitivity of the optical sensing system.
Implementation Method 1
The photodiode converts the received radiant energy to electrical current which is further processed for detecting, for example, the existence of a moving object
Implementation Method 2
an optical sensing system may drive an LED to emit light in certain wavelength range
Data Source
AI summary
An optical detection system includes a first device that has a first light source and a first light detector, and a second device that has a second light source and a second light detector. The first and second devices are configured to turn on and off the first and second light sources periodically based on first and second control signals, respectively. The first and second light sources are configured not to emit light simultaneously. The first and second light sources emit light in wavelength ranges that overlap. The optical detection system further has the characteristic that when the first light source is turned on, a radiant power delivered to the second light detector from the first light source is at least 25 percent of a radiant power delivered to the first light detector from the first light source.