Optical Moisture Sensor With Self-Cleaning Lens
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Solution Overview
Problem
Existing moisture sensors for non-vehicular applications lack sensitivity, reliability, and maintenance efficiency, particularly in detecting extremes of humidity and precipitation, and are not suitable for desert environments or condensation sensing in HVAC systems.
Innovation Solution
A self-contained optical moisture sensor with a hemispherical lens and control circuitry, featuring a geometrically shaped lens for improved light transmission and reflection, and software-configurable for various applications, providing a wide sensing area and low maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional moisture sensors are used in non-vehicular applications, then basic moisture detection is possible, but sensitivity to extremes of humidity and precipitation is insufficient
Solution Approach 1:
The patent transitions from conventional point-contact moisture sensors to an optical sensing approach that detects moisture through light interaction with a sensing surface. This dimensional shift from direct contact to optical field interaction enables detection of moisture extremes with higher sensitivity and reliability, as the optical method can detect subtle changes in light properties caused by moisture presence without requiring direct physical contact.
Solution Approach 2:
The invention replaces mechanical or electrical contact-based moisture sensing mechanisms with an optical detection system. By using light emitters and detectors to sense moisture through optical property changes rather than physical contact, the system achieves superior sensitivity to moisture extremes while maintaining reliability across diverse environmental conditions.
2Reliability
If conventional moisture sensors are deployed in harsh environments like deserts or HVAC systems, then basic operation is possible, but maintenance requirements increase and accuracy decreases
Solution Approach 1:
The optical sensing surface is designed to be self-cleaning through its optical properties and geometry. Moisture droplets and contaminants on the sensing surface naturally alter light transmission in detectable ways, allowing the system to identify and compensate for surface conditions without manual intervention. The optical method inherently detects the presence of moisture regardless of minor surface contamination, reducing maintenance needs in harsh environments.
Solution Approach 2:
The patent introduces an optical intermediary (light) between the sensor and moisture, allowing indirect detection that is less susceptible to environmental contamination. This intermediary approach enables accurate moisture detection in harsh conditions like deserts and HVAC systems without requiring direct physical contact that would be affected by dust, debris, or surface degradation.
3Area of stationary object
If a self-contained optical moisture sensor is designed with a geometrically shaped lens for improved light transmission, then sensing area and sensitivity increase, but device complexity increases
Solution Approach 1:
The patent employs a geometrically shaped lens with specific curvature to focus and transmit light through the sensing area. The curved optical surface increases the effective sensing area by directing light from a broader region to the detector, thereby enhancing sensitivity without proportionally increasing device complexity. The geometric shape optimizes light paths to maximize detection capability within a compact form factor.
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 sensor offers enhanced sensitivity to both high and low humidity and precipitation events, is cost-effective, and maintains accuracy in harsh environments, including desert conditions and HVAC systems, with self-cleaning properties and efficient condensation detection.
Implementation Method 1
at least one light emitter, and at least one light detector being mounted on the circuit board
Implementation Method 2
The lens is capable of receiving and transmitting therethrough, solar radiation on the outer sensing surface from sources external to the self-contained moisture sensor unit
Implementation Method 3
reflecting light rays from the inner sensing surface emitted by the at least one light emitter disposed within the self-contained moisture sensor unit
Data Source
AI summary
A moisture sensor is provided that simultaneously achieves ruggedness, sensitivity, wide dynamic range, versatility of application, and low cost. The outer, top service of the sensor is a lens having a predetermined geometric shape which preferably makes the rain sensor resistant to the build up of debris on the outer surface as well as being effectively self-cleaning. Within a housing of the rain sensor, at least one light emitter and at least one light detector are each deployed on a substantially planar circuit board facing such outer lens surface. So arranged, light rays from the at least one emitter strike the outer lens surface and is reflected about 90°, whereupon it strikes the outer lens surface once more and is again reflected therefrom about 90° to focus back onto the at least one detector. Raindrops present on the outside surface of the sensor affect the intensity of the light rays reflected and signals from the at least one light detector are sent to control circuitry within the rain sensor. A microprocessor in the sensor processes the resulting data to detect rain intensity over a wide range so as to be capable of being effectively deployed for applications such as to emulate a tipping bucket style rain detector, providing condensation sensing, and automatically adjusting the strength of the light rays emitted by the at least one light emitter to provide improved consistency of operation of the sensor over time.