Detection based on “Light”
Detection method and feature of Photoelectric Sensors

Photoelectric sensors emit light from a transmitter. Detection is based on how much or how little of this light makes it to the receiver. This section explains the features of the various photoelectric sensor detection systems.

Classification

Thrubeam

Thrubeam

Detection occurs when the target crosses the optical axis between the photoelectric sensor's transmitter and receiver.

  • ・Long-detecting distance
  • ・Stable detecting position
  • ・Opaque objects detectable regardless of shape, color or material
  • ・Powerful beam

Retro reflective

Retro reflective

Detection occurs when the target crosses the optical axis between sensor head and reflector.

  • ・Reflector allows installation in a limited space
  • ・Simple wiring
  • ・Longer detecting distance than the diffuse-reflective sensor type
  • ・Easily-adjustable optical axis
  • ・Opaque objects detectable regardless of shape, color, or material

Diffuse reflective

Diffuse reflective

Detection occurs when the light beam, emitted to the target, is reflected by the target and received.

  • ・Space-saving (requires installation of sensor unit only)
  • ・Adjustment of optical axis not required
  • ・Reflective transparent objects detectable
  • ・Color differentiation possible

Focused beam reflective

Focused beam reflective

Detection occurs when the beam spot, emitted to the target, is reflected by the target and received.

  • ・Minute objects detectable
  • ・Target markings detectable
  • ・Detection possible through narrow openings between machines
  • ・Visible beam spot

Small-spot definite reflective

Small-spot definite reflective

The transmitting and receiving portions are constructed at an angle, allowing detection within the limited area where the optical axes intersect.

  • ・Effect of target background is minimal
  • ・Low hysteresis
  • ・Slight height differences are detectable
  • ・Visible beam spot

Fixed distance

Fixed distance

Detects the target at a specific distance according to the angle of the reflected light beam.

  • ・Unaffected by highly reflective targets or backgrounds
  • ・Stable detection of materials with varying reflectance and color
  • ・Highly accurate detection of minute objects
  • ・Visible beam spot

Luster recognition

Luster recognition

When the light beam hits a target, the beam reflects differently according to the luster of the target. The sensor detects the difference in luster based on how the beam reflects (specular or diffusive).

  • ・On-line detection is possible.
  • ・Detection is not affected by target color.
  • ・Transparent targets can be detected.

INDEX

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