Variations of diffuse mode photoelectric sensing include proximity, sharp cutoff, fixed focus, convergent beam, divergent beam, wide angle, fixed field, background suppression and foreground suppression. Diffuse sensors operate on the principal that when a light source is shined on a surface the light is scattered or diffused in many directions. A small portion of the light, which can be infrared, red or laser, is reflected back to the sensor receiver. The receiver used in this style of sensor is designed to be sensitive to a weaker or smaller amount of light that is reflected back from the target surface, which in turn activates the output. Sensing ranges that vary from a maximum of 50 mm to 2000 mm are dependent on the target reflectivity.
One of the advantages of the diffuse or proximity style photoelectric sensors is the light emitter or light source and the receiver are in the same enclosure thus you only have a single device to mount and wire making installation easier and faster. This is a huge benefit in space restrictive locations or in those applications where you cannot get to both sides of the target as would be required with through-beam or retro-reflective. Since there is, only one device the diffuse photoelectric sensor is typically cost effective as compared to the retro-reflective or through beam sensors.
Applications:
- Part presence
- Error proofing
- Fill
- Product height
- Lid presence