28-08-2012, 05:08 PM
RAIN ACTIVATED INTELLIGENT WIPER
RAIN ACTIVATED INTELLIGENT WIPER.doc (Size: 30.5 KB / Downloads: 99)
A windshield wiper system activated by sensing rainwater via a rain sensor placed inside the wiping pattern when a multifunction switch lever is in automatic mode. A rain sensor module activates a relay for low speeds and/or a relay for high speeds depending on the detected amount of rainwater. A first voltage detecting means detects battery voltage, a second voltage detecting means detects voltage of an automatic signal, and a microcomputer adjusts the sensitivity of the rain sensor based on a voltage ratio of the automatic signal voltage and the battery voltage. A reformed wiring structure connects the multifunction switch and the rain sensor module, which contributes to a reduction of the weight and cost of the wiring harness. The sensitivity of the rain sensor is not affected by a voltage change.
The technology behind rain-sensing wipers is not complicated. A small area of the front windshield glass (usually located on the outside of the vehicle, opposite the rear-view mirror) is monitored by an optical sensor. The sensor is designed to project harmless infrared light at the windshield at an angle and then read the amount of light that is reflected back. A clean windshield will reflect nearly all of the light back, while a wet or dirty windshield will cause the light to scatter. The optical sensor can determine the necessary frequency and speed of the windshield wipers by monitoring the amount of light reflected back into the sensor.
As a safety precaution, and to prevent damage to the wiper mechanism, nearly all rain-sensing wipers must be activated each time they are used. The activation process prevents the system from automatically wiping a frozen windshield, or triggering while the vehicle is in a car wash; both instances could damage the blades or electric motor powering the wipers.