A light curtain, or safety light curtain, is a presence-sensing device that protects operators from hazardous equipment. At the most basic level, it is an invisible barrier made of multiple infrared beams sent from one device, an emitter, to a second device, a receiver. If these infrared beams are broken by a person or object, the machine stops. But there’s a lot more to protecting operators than just breaking a beam of invisible light.
Light curtains typically have two main machine guarding duties: access guarding or perimeter guarding. When a light curtain is used for access guarding, it protects specific access points to a hazardous area. This area can be large or small, depending both on the area that needs to be safeguarded as well as what may trigger the light curtain. When used for perimeter guarding, larger light curtains are set around a machine or other piece of equipment and prevent access to the surrounding area. This takes up more floor space, but allows greater flexibility in approaching equipment.
Applications in which light curtains may be a preferred protection method include:
- Guarding against moving parts on machines
- Avoiding pinching or crushing hazards
- Controlling personnel access to restricted areas
- Managing items on packaging and sorting lines
- Preventing machine startup during maintenance
Because light curtains offer non-contact machine guarding, they typically last much longer than mechanical devices like door switches, which can wear over time due to repeated locking and unlocking. Also, less floor space is needed because there’s no physical door needing room to swing open.
