Light Intensity Detection Using Pulse Duration Measurement
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Solution Overview
Problem
Existing light intensity detecting methods using pulse signals from light sensors are prone to errors due to external noise, especially in low-light environments, leading to inaccurate determination of environmental light intensity with approximately 10% error.
Innovation Solution
A light intensity detecting device comprising a time measuring unit, signal state discriminating unit, sampling unit, and falling detecting unit, which measures the elapsed time of the pulse signal, discriminates its state, and corrects the pulse duration by multiplying the reciprocal with a predetermined constant to account for noise, thereby accurately determining light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pulse duration is measured directly from the light sensor output, then the measurement process is simple, but the measurement precision deteriorates due to noise interference causing approximately 10% error
Solution Approach 1:
The patent applies preliminary action by measuring the pulse width at a predetermined time point before the pulse ends, rather than waiting for the pulse to complete. This allows the system to capture the pulse duration information early in the pulse cycle, avoiding the noise interference that occurs during the error period at the end of the pulse, thereby improving measurement accuracy without requiring complex noise filtering mechanisms
Solution Approach 2:
The patent extracts only the necessary measurement information (pulse width at a specific time point) from the pulse signal, rather than attempting to measure the entire pulse duration. By taking out only the critical measurement point before noise interference occurs, the system achieves accurate light intensity measurement while simplifying the detection process and avoiding the need to handle the noisy error period
2Measurement precision
If the error period is discarded to improve measurement accuracy, then the precision improves slightly, but the loss of time increases due to discarding valid measurement data
Solution Approach 1:
The patent performs the measurement action preliminarily by capturing the pulse width information at a predetermined time point before the error period begins. This approach eliminates the need to discard any measurement data since the valid measurement is obtained early in the pulse cycle, thereby improving accuracy without incurring time loss from discarding valid data
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 solution effectively reduces noise interference, providing a more accurate light intensity measurement with a maximum error of 2×(1/f) seconds, enhancing the detection accuracy compared to prior art methods.
Implementation Method 1
a light sensor for detecting environmental light generates an output signal according to the intensity of the received light
Data Source
AI summary
A light intensity detecting device is provided to detect a light intensity according to pulse duration of a pulse signal without being affected by noise, including: a time measuring unit for measuring an elapsed time period of the pulse signal that has been raised; a signal state discriminating unit for obtaining a state of the pulse signal; a sampling unit for directing the signal state discriminating unit to obtain the state at a sampling interval corresponding to the elapsed time period; and a falling detecting unit for detecting the pulse signal that has been fallen when a fallen state of the pulse signal is successively obtained for two times. When the fallen pulse signal is detected, the sampling unit directs the signal state discriminating unit to obtain the state of the pulse signal at a time point, which is output as the pulse duration of the pulse signal.