Automatic wiper Automatic wiper

Automatic wiper

The automatic wiper is a function that operates the wiper automatically when it starts to rain. It uses a raindrop detection sensor (rain sensor) to control the wiper.
Normally a rain sensor is installed near the windshield, and combines near-infrared light and Si photodiode to detect raindrops. Hamamatsu offers optical semiconductor devices including infrared LEDs and Si photodiodes, which can be configured in rain sensors.

In recent years, it is also necessary to make rain sensors more compact and integrated with other sensors that monitor the external environment, such as sunlight detectors and light and dark detectors, with consideration for the interior design of vehicles when increasing the number of sensors installed in them. Hamamatsu can also provide optical semiconductor devices with custom specifications that meet such requirements.

Mechanism of rain sensor

When there are no raindrops on the windshield, infrared light emitted from the LED is reflected off the windshield surface and strikes the Si photodiode. When there are raindrops on the windshield, less infrared light strikes the Si photodiode because infrared light has to pass through the raindrops. The principle of this mechanism is to identify whether or not there are raindrops (water). It also distinguishes between heavy rain and light rain based on the amount of light input into the Si photodiode, and in order to automatically control the speed of the wiper.

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