Photoelectric Sensors

Photoelectric sensors detect and measure physical objects or quantities by emitting a field or beam of electromagnetic radiation, an object is detected by measuring alterations in the return signal. There are 3 main types of photoelectric sensors which provide reliable detection, these are through-beam, retro-reflective and diffuse. The basic function of each is to detect the presence or absence of objects or measure the distance to the object.


Through-beam Sensors


Through-beam sensors (aka thru-beam) rely on two separate housings, one for the transmitter and one for the receiver, with the transmitter providing a continuous beam of light to the receiver. Each time an object passes through the beam this interrupts the signal between the transmitter and receiver, which in turn causes the receiver to send an electrical signal to the output. Through-beam sensors are suited to long-distance sensing and are capable of detecting almost any object, irrespective of colour or angular motion.


Retro-reflective Sensors


Retro-reflective photoelectric sensors (retroreflective) have both the transmitter and receiver contained within the same housing but require a reflector opposite to the sensor. The reflector bounces the light beam back to the transmitter until an object breaks the beam. Objects which are highly reflective such as aluminium require sensors with polarising filters. The filter allows the sensor to acknowledge that the reflected light from reflecting materials is different from the reflector.


Diffuse Sensors


Diffuse sensors (proximity sensor) are easier to install as only one device has to be mounted. This is because the transmitter and receiver are contained within one housing. Diffuse sensors use the reflection from the target object within a predetermined sensing range. The transmitter sends out a continuous beam of light, once this hits the target it is diffused in all directions, a part of this light is reflected back and recognised by the receiver, the receiver then sends an electrical signal to the output.


A special type of diffused mode is background suppression which enables the user to precisely control the sensing range. A diffuse mode sensor with background suppression is less sensitive to the target colour. They can also use a visible red light or infrared light sources.


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Description Price Sensor Style Detection Type Detection Range Output Type Electrical Connection Maximum AC Voltage Maximum DC Voltage Terminal Type Light Source IP Rating Maximum Current Interface Response Time Housing Material
RS Stock No. 847-0331
Mfr. Part No.13104RQD07
BrandEaton
HK$1,492.60
Each
units
Block Diffuse Maximum of 50 mm NPN/PNP 4-Pin Connector - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 1 ms Polyurethane
RS Stock No. 847-0261
Mfr. Part No.13100A6517
BrandEaton
HK$1,109.82
Each
units
Block Diffuse Maximum of 610 mm NPN/PNP Cable - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 1 ms Polyurethane
RS Stock No. 847-0255
Mfr. Part No.12102A6517
BrandEaton
HK$1,174.53
Each
units
Block Through Beam (Receiver) Maximum of 24 m NPN/PNP Cable - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 3.5 ms Polyurethane
RS Stock No. 847-0319
Mfr. Part No.13104A6517
BrandEaton
HK$1,319.52
Each
units
Block Diffuse Maximum of 50 mm NPN/PNP Cable - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 1 ms Polyurethane
RS Stock No. 847-0252
Mfr. Part No.12102AQD07
BrandEaton
HK$1,310.31
Each
units
Block Through Beam (Receiver) Maximum of 24 m NPN/PNP 4-Pin Connector - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 3.5 ms Polyurethane
RS Stock No. 847-0249
Mfr. Part No.12100AQD07
BrandEaton
HK$1,093.18
Each
units
Block Through Beam (Receiver) Maximum of 6 m NPN/PNP 4-Pin Connector - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 3.5 ms Polyurethane
RS Stock No. 847-0371
Mfr. Part No.13108AQD07
BrandEaton
HK$1,492.60
Each
units
Block Diffuse Maximum of 150 mm NPN/PNP 4-Pin Connector - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 1 ms Polyurethane
RS Stock No. 847-0766
Mfr. Part No.E65-SMTS15-HA
BrandEaton
HK$637.11
Each
units
Block Through Beam (Emitter) Maximum of 15 m NPN/PNP Cable - 30V - LED IP68 100 mA - 1 ms Cycoloy
RS Stock No. 847-0343
Mfr. Part No.13105AQD07
BrandEaton
HK$1,492.60
Each
units
Block Diffuse Maximum of 50 mm NPN/PNP 4-Pin Connector - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 1 ms Polyurethane
RS Stock No. 847-0567
Mfr. Part No.E58-18DP100-HL
BrandEaton
HK$2,909.62
Each
units
Barrel Diffuse Maximum of 100 mm NPN/PNP Cable - 30V - LED - 250 mA - 1 ms Stainless Steel
RS Stock No. 847-0236
Mfr. Part No.11102AQD07
BrandEaton
HK$988.51
Each
units
Block Through Beam (Emitter) Maximum of 24 m NPN/PNP 4-Pin Connector - 30V - LED IP69K 100 (PNP) mA, 250 (NPN) mA - 3.5 ms Polyurethane