Rain Sensor Daylight Compensation Circuit
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Solution Overview
Problem
Existing rain/liquid sensors lack accuracy and reliability, particularly in applications requiring precise measurements of falling liquid amounts, and are susceptible to interference from varying daylight conditions.
Innovation Solution
A differential circuit rain/liquid sensor with a daylight sensor to adjust the LED's light intensity, using a differential circuit to provide a reliable measurement of light absorption by falling drops, and incorporating a daylight shielding element and compensation circuit to minimize daylight interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple light transmitter and receiver are used, then the device complexity is reduced, but the measurement precision deteriorates due to inability to compensate for daylight variations
Solution Approach 1:
The patent employs a feedback mechanism where the daylight sensor continuously monitors ambient light conditions and feeds this information back to the control circuit, which then adjusts the LED transmitter intensity accordingly. This closed-loop feedback system compensates for daylight variations without significantly increasing device complexity.
Solution Approach 2:
The patent changes the operating parameter of the LED transmitter dynamically based on measured daylight intensity. The control circuit adjusts the LED current or duty cycle in response to daylight sensor readings, thereby adapting the transmission parameter to environmental conditions while maintaining measurement precision.
2Reliability
If the LED light intensity is increased to improve signal strength, then the signal-to-noise ratio improves, but the susceptibility to daylight interference increases
Solution Approach 1:
The patent takes preliminary action by measuring daylight intensity before the rain measurement cycle begins. The control circuit uses this advance information to pre-adjust the LED transmitter intensity to an optimal level that maximizes signal strength while minimizing susceptibility to daylight interference during the subsequent measurement period.
Solution Approach 2:
The daylight sensor provides continuous feedback on ambient light conditions, allowing the control circuit to dynamically adjust LED intensity in real-time. This feedback loop enables the system to maintain optimal signal-to-noise ratio while compensating for varying daylight interference levels.
3Measurement precision
If a differential circuit is used to improve measurement accuracy, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent merges the differential circuit functionality with the existing signal processing circuitry. The differential measurement approach is integrated into the receiver circuit design, combining multiple functions into a unified circuit architecture that improves measurement precision without proportionally increasing device complexity.
Solution Approach 2:
The control circuit is designed to perform multiple functions: it processes the receiver signal, compensates for LED intensity variations, and adjusts transmitter intensity based on daylight conditions. This multi-functional approach reduces the need for separate dedicated circuits, thereby limiting the increase in device complexity while maintaining high measurement precision.
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 enables accurate and reliable measurement of rainfall or liquid amounts, reducing the impact of daylight variations and providing improved precision for applications needing greater accuracy, such as remote weather stations and irrigation systems.
Implementation Method 1
a light transmitter (2) having at least one LED (3) which is arranged to transmit light of a certain intensity
Implementation Method 2
a light receiver (5) which is arranged to receive the transmitted light after it has travelled through the outside air and convert it to an electric output signal
Implementation Method 3
a daylight sensor (14) connected to said element, which daylight sensor measures the intensity of daylight in the outside air
Data Source
Figure 1
AI summary
A description is given of a rain/liquid sensor comprising: - a light transmitter which is arranged to transmit light of a certain intensity, - a light receiver which is arranged to receive the transmitted light after it has travelled through the outside air and convert it to an electric output signal which contains a measure of the absorption of the transmitted light experienced in the outside air, and - a differential circuit with inputs connected to the light transmitter and the light receiver and an output for supplying an electric differential signal thereto, the differential signal comprising a measure of a current quantity of falling liquid drops or rain in the outside air.