Proximity Photoelectric Switch

Photo Electric Sensors works on the principle of modulated Infra-Red rays. These photoelectric beam sensors can sense any opaque, semi-transparent objects which comes in its sensing range. Photo Electric Sensors have large operating distance. Photoelectric beam sensors are mainly divided into : Diffused Beam Sensors, Through Beam Sensors with Amplifier Unit, Through Beam Sensors with Built in Amplifier, Retro-Reflective Sensors.

Working Principle
This diffused photoelectric beam sensors consist of a transmitter and a receiver together. These beam sensors look alike Inductive Proximity Sensors and hence also known as IR Proximity Sensors. The emitter emits Infra red rays which are reflected on the receiver through the object to be registered. In the use of these photoelectric sensors, it is important to bear in mind the colour of the object. Light colour corresponds to the maximum distance and vice versa. In case of shiny object; the effect of surface of object is more important than the colour.

Advantages

• Transmitter and receiver are housed in the same housing.
• As the self reflection of an object is used for detection; Dark & Light marks can be distinguished.

Field of application
These beam sensors are particularly used for position sensing and counting of non metallic objects. It is also used for Bottle sensing, Level sensing, Height sensing Plastic film sensing Edge detection of paper or sheet metal etc.

Working Principle
This through beam photo electric sensors consist of two devices; a light emitter and a light receiver These two devices are kept apart facing each other. The Gallium-Aluminium-Arsenide-Luminescent diode integrated in the transmitter sends pulses of light in the infra-red range which are invisible lo the human eye. The receiver opposite to the transmitter receive these rays. Sensing is achieved when these rays are interrupted by the object.

Advantages

• Large sensing distance is possible as emitter and receiver are kept opposite to each other.
• Suitable for precise detection of large as well as small objects.
• Repeatability and indexing precision are not impaired even if the object surface or background is reflecting

Field of application
Through Beam Sensors are used for sensing semitransparent opaque objects such as Glass/Plastic Bottle, Sliver breakage detection, Paper breakage detection. Door opening/closing etc.

Working Principle
This consist of two devices, a light emitter and a light receiver. The light receiver device contains amplifier circuit which gives transistorised output. These two devices are kept apart facing each other. The transmitter sends pulses of light in the infrared range which are invisible to the human eye. The receiver device opposite to the transmitter receives these rays. On interruption of these rays by the target object, receiver gives a signal which is amplified and fed to output transistor.

Advantages

• Large sensing distance is possible as emitter and receiver are kept opposite to each other.
• Suitable to precise detection of large as well as small objects. Repeatability and indexing precision are not impaired even if the object surface or background is reflecting.
• Can be coupled directly to PLC.

Field of Application

• Silver Breakage detection.
• Bottle sensing.
• Door opening / closing.
• Film sensing.
• Counting objects on moving conveyor.

Working Principle
This is a system which consist of one device and a reflector. The device contains emitter and receiver The rays emitted by the emitter are reflected by the reflector to the receiver. The sensing of the object occurs when these rays are interrupted.

Advantages

• Easy assembly compared to the through beam type.
• Large active sensing range compared to diffused beam type.

Field of Application
This sensors can be used where it is difficult to install Through Beam Sensors due to space constraint. Further, simple wiring makes it suitable where sensing objects are bigger in size. Thus these sensors are used for loop control in decoiler, edge detection in paper/sheet metal etc.

Print mark sensors are used for sensing registration mark on packaging film. These sensors include state-of-the-art technologies for providing precision results. These sensors are used in various industrial segments.

Working Principle
This is designed for sensing Registration Marks. It continuously scans the presence of registration mark on the moving packaging film. The electronic circuitry is capable of detecting / scanning any colours on any Background colour. A modulated, Green LED is focused on the moving packaging film. A highly sensitive Photo cell continuously accepts the reflections from the film (paper / plastic) and sends the signals to the electronic scanning circuit. On scanning the presence of Registration Mark; it gives transistorised output.

A logic controller is also provided which accepts signals from scanning head & other Proximity Sensors to keep correct pouch / bag length by driving correction motor (110V AC, 4wire) or (230VAC, 3 wire).

Salient Features

• Fully solid state thus making it totally reliable.
• Immune to external light source, electrical interference.
• A selector switch provided to choose Dark switching or light switching.
• High speed switching i.e. 2000 marks/min.
• Detection of different contrast sheds by means of sensitivity pot provision.

Print Mark Sensors With Teach – In Function
This is with micro controller based technology, wherein user has to press SCAN key (a feather touch key), keeping White spot light on Mark colour as well as on background colour and within 2-3 sec both colours will get registered in memory. The electronic scanning circuit then differentiate both colours and gives out put on detection of Registration Mark.