Rain Sensors | Light Sensors | Optoelectronic Sensors | Passive Light Sensor

Rain sensor systems:

Opto electronic sensors are used in a reflective mode in rain sensor systems to detect the presence of water on the windshield so that the windshield wipers can be controlled automatically.

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An LED emits light in such a way that when the windshield is dry almost the entire amount of light is reflected onto a light sensor. When the windshield is wet, the reflective behavior changes: the more water there is on the surface, the less light is reflected. In the new rain sensor, infrared light is used instead of conventional visible light. This means that the sensor can be mounted in the black area at the edge of the windshield and cannot be seen from outside.

Working Operation:

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An infrared beam is reflected off the outer windshield surface back to the infrared sensor array. When moisture strikes the windshield, the system detects a reflection to its infrared beam. Advanced analogue and digital signal processing determines the intensity of rain. The sensor communicates to the wiper control module, which switches on the wiper motor and controls the wipers automatically, according to the moisture intensity detected.

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Depending on the quantity of rain detected, the sensor controls the speed of the wiper system. In conjunction with electronically controlled wiper drive units, the wiping speed can be continuously adjusted in intermittent operation. In the event of splash water – as when overtaking a truck – the system switches immediately to the highest speed.

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The new rain sensor offers further options. For example, it can be used to close windows and sunroofs automatically if the vehicle is parked and it starts to rain. It can even be fitted with an additional light sensor to control the headlights – at night or at the entrance to a tunnel, the lights can be switched on without any intervention by the driver.

For Windshield wipers working operation Click this Link.

Light Sensors:

Automatic lighting of the headlights is controlled by a passive light sensor. It measures available light using a set of photo-electric cells.

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The light sensor comprises three lenses that focus the light onto three photo-electric cells. This allowed “the luminous space” surrounding the vehicle into several zones through the directivity of each basic lens cell pair.

  • Lens 1: Measure total ambient light
  • Lens 2: Intersect Front source of light
  • Lens 3: Distinguish Road Condition (Like brighter sunny weather condition or Dark tunnel)

By comparing the information gathered by these three devices, the system computer determines the situation with which the vehicle is confronted and commands the headlights in consequence.

Opto Electronics | Fiber Optics Technology | Optoelectronic Sensors | Opto Electronics An Introduction

Optical techniques have always been used for a large number of automotive, metrological and sensing applications. Fiber- and integrated- optics technologies were primarily developed for telecommunication applications. However, the advances in the development of high quality and competitive price opto-electronic components and fibers have largely contributed to the expansion of guided wave technology for sensing as well.

What is Opto-Electronics?

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It is the branch of electronics dealing with devices that generate, transform, transmit, or sense optical, infrared or ultraviolet radiation, as solar cells and lasers.

Optoelectronic devices are used to activate or deactivate an electronic circuit based on the intensity of light. Besides this general purpose, optoelectronics devices are used in telecommunication, surveillance systems, capturing solar energy etc. Solid state optoelectronic components are used as sensors for detecting visible light, Laser Infrared rays, Ultraviolet rays etc.

What is Opto-Electronic Sensor?

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An opto-electronic sensor is a device that is capable of producing an electrical signal that is proportional to the amount of light incident on the active area of the device.

Integrated optoelectronic sensors are designed to recognize fundamental stimuli such as patterns, images, motion and intensity and colour.

Types of Opto-electronic Sensors:

Optoelectronic Sensor Type


Light to voltage converters

Convert linear output voltage proportional to light intensity

Light to frequency converters

Convert light intensity to digital format for direct connection to microcontroller or Digital signal processor

Ambient light sensors

Measure what the human eye sees

Linear sensor arrays

Measure spatial relationships and light intensity

Colour sensors

RGB filtered sensors for colour discrimination, determination and measurement

Reflective light sensors

Convert reflective light intensity to voltage output