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Safety Light curtains / Light screens buying guide
Applications, & Safety requirements for industrial safety


Light curtains are basically a screen of infrared light beams that form an invisible barrier. Light curtains provide for both safety of the operator and protection of equipment, such as robotic cells. Sometimes light curtains are also referred to as light screens or optical guards, either way they are used for safeguarding many hazardous situations. Protective light curtains provide a high level of safety if applied correctly to the application and conditions.

Applications and interfacing considerations- light curtains and light screens

  1. Motion must be capable of stopping anywhere within its stroke or cycle.
  2. Equipment stopping time must be consistent
  3. Severe environment- large amounts of smoke, coolant mist, particulate matter or corrosive chemicals.
  4. Risk assessment of injuries and safe stopping distances
  5. Recovery of machines and cells affected.

Justification for buying safety light curtains, light screens

  1. Safety
  2. Increase cycle time
  3. Prevent damage to equipment (cost of one accident, downtime, or delivery on parts)
  4. Ergonomics- prevent carpal tunnel claims (Example- opening and closing doors all the time)
  5. View process without looking through a window for verification or problems without stopping operation.
  6. OSHA fines for safety
  7. Employee- Medical costs, lost wages, or training a replacement employee
  8. Insurance increases

Safe guarding applications for Light curtain sensors ?

  1. Fixtures Clamping that requires the door to be open or conditions where pinch/injury points are present (also consider anti tie down control)
  2. Servo or pneumatic automatic doors consider light curtains or a bumper safety switch .
  3. Robotics Its usually a good safety precaution to prevent the robot, person, or any object from being inside the machine opening of the machine tool. This setup is also beneficial if the cell breaks down, the operator would then be able to load the machine by hand.

    Another condition that is also good to safety standard is the manual operation with the teach pendant or machine control .

    When moving machines or robot by hand you often bypass certain program safety conditions. With a light curtain this will protect the robot from entering or stop the machine at any point in time. Example- pallet change in MDI or manual recovery. This can do severe damage to the robot or machine.

Basic light curtain or light screen options and considerations

  1. Beam spacing- 12mm/14mm/20mm/30mm etc.
  2. length of curtain
  3. Interface control type- box, safety module or force guided relays.
  4. Range between transmitter and receiver

Well known brands of light curtains

  1. STI safety light curtains- Example MC4700
  2. Sick safety light curtains- Example C4000
  3. Banner safety light screens-