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IR Windshield Rain Sensor

In this project a rain and ice sensor is implemented by analyzing the reflection of an infrared (IR) light source using GreenPAK™ SLG46620V.

In this project, a rain and ice sensor is implemented by analyzing the reflection of an infrared (IR) light source.

This project will use proven techniques based on multiple reflections of IR light in the internal walls of the target glass. It will aim to increase the capabilities of standard components by adding technical advantages offered by the LED device, such as increasing the power emission using pulsed energy applied ten times using high current strikes at one percent duty cycle.

Below we described steps needed to understand how the solution has been programmed to design a rain sensor. However, if you just want to get the result of programming, download GreenPAK software to view the already completed GreenPAK Design File.Plug the GreenPAK Development Kit to your computer and hit the program to design the solution.

The most common practice in the detection of raindrops on a windshield involves sensing infrared light conducted through the internal walls of the windshield glass, and in some cases enhancing these reflections by adding other physical components to the glass.

When raindrops are present on the external surface of the glass, a refraction of light happens and takes away part of the initial light stream. This results in an attenuated beam of IR light as compared to the original conditions (without the presence of water).

In order to acquire the majority of the luminous emissions, the light beam is injected into the glass at a 45° angle. The receiver at the other end of the glass also has a 45° angle. This technique depends on the statistical probability that when it is raining, the surface of the glass will have raindrops in the path of reflection. The longer the distance between the emitter and receiver, the more effective this detection method will be.

As the distance between the emitter and receiver gets bigger, the light’s power loss increases as the light travels through the glass. For the best detection given increasing distance, either a more efficient sensing/light emission device must be developed, or more power must be obtained from the current IR light source.”

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