Referring the definition of photo electric sensor that has been described previously, Photo electric sensor is the sensor that detect the object by transmitting a beam with intensity that has been determined. The beam can be infra red or photo electric. All object can be detected by these sensors, because the sensor detects the light emitted by the object being detected.
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| Photoelectric by Keyence |
2. Receiver, receiving the beam after the object is detected.
Categories of this sensor can be distinguised based on the transmitter emits the light into object and received it. Based on this, there are three kinds of models as shown below:
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| 3 models of Photoelectric E3Z by Omron |
- Through-beam, Transmitter and receiver separated or opposite, object detected by how much lights is received by the receiver as the result of obstruction of light by the oject.
- Retro-reflextive, Transmitter and receiver is in one side. After passing through the object, light reflected through the reflector and then received by the receiver. Reflector ussually is a mirrow.
- Difuse-reflective, Transmitter and receiver is in one side. Almost as retro-reflective, but this model directly detect the intensity of light reflected by the object.
Various models of photoelectric sensors on the market. Some of the maker that there is such Keyence, Omron, Fuji and so on. There are categories or variations of the models that would fit with existing applicationa. As with any model with a separate amplifier and the sensor head, amplifier and sensor head in one package, built in amplifier and so on.
" Light ON and Dark ON" mode on Photoelectric sensor:
One of the important things in the photoelectric sensor is how free condition at the time of detecting object. Free condition is when the sensor is free from object.
As a simple illustration, the following picture describes the " Light ON and Dark ON",
1. Light ON mode:
" Light ON and Dark ON" mode on Photoelectric sensor:
One of the important things in the photoelectric sensor is how free condition at the time of detecting object. Free condition is when the sensor is free from object.
As a simple illustration, the following picture describes the " Light ON and Dark ON",
- Condition A, conditions with no object then the sensor output is ON.
- Condition B, condition with object then the sensor output is OFF.
2. Dark ON mode:
- Condition A, conditions with no object then the sensor output is OFF.
- Condition B, condition with object then the sensor output is ON.
Seen from the above description that the Light On and Dark On is the opposite condition. Selection of this mode is largely determined by the object being detected or safety reasons.
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