Rain Sensor: Description and Operation
RAIN SENSORDESCRIPTION
The Rain sensing windshield wiper system is a wiper system that, in addition to providing normal wiper functions off, mist, manual low speed, manual high speed, and wash, provides automatic control of automatic intermittent automatic low, and automatic high speeds.
When the ignition key is in the ON position, the rain sensor will be activated.
SYSTEM FUNCTION
BASIC PRINCIPLE
Emitted Beam from luminosity diode is reflected entirely against the windshield exterior, and then into photo diode. If there is water on the windshield exterior, beam separates optically, and the degree of remained beam is measured in the photo diode.
What there is water in the windshield, it means beam is not reflected all, so the degree of lost beam indicates the degree of glass surface wet.
NOTE: Rain sensor consists of two luminosity diode, two photo diode, optic fiber and coupling pad.
OPERATION CONTROL
Wiper ECU transmits the signal as a rain sensor, and then the rain sensor perceives the rainwater to transmit to the wiping order wiper ECU, wiper ECU controls the wiper motor according to the signal.
CONTACT INFLUENCE
Rain sensor can misoperate according to behind condition
- Measurement signal gets weak by the dust of measurement surface or all beam way surface (the surface of luminosity and photo diode, optic fiber, coupling pad, windshield copula glass surface).
- The bubble on the windshield and the coupling pad contact surface.
- The movement of coupling pad by vibration.
- Damaged wiper blade.
OPERATION CONDITION
In case that engine starts under wiper switch AUTO, rain sensor activates after once wiper operation to inform the driver that the system is under AUTO.
NOTE: In case that the rain sensor doesn't work or malfunction, it is needed manual wiper switch operation by the driver.