Light Curtains

Industrial environments can be dangerous and operator safety must be the top priority when operating and maintaining hazardous machinery. Traditionally, physical barriers, such as pull-back restraints and sliding gates, were used to protect operators from hazardous machines. Now, a light curtain barrier can be used instead, allowing operators easier access to perform routine tasks, maintenance and repair.

Light curtains are considered presence detection devices and have two important components: a transmitter and a receiver. The transmitter sends infrared light beams to the receiver in a known sequence and at a specific frequency. The receiver anticipates the beams of light in the known sequence and frequency, reducing the possibility of interference from other light sources. When an object passes between the transmitter and receiver, the light from the transmitter is interrupted and not received by the receiver, triggering a stop signal. This stop signal is typically sent to a safety relay, which will remove power from the machine.

Light curtains are generally used in two situations: perimeter and point of operation. Perimeter guards protect the boundary or perimeter of an entire working space around a machine. Light curtains used in perimeter guarding applications are generally selected for torso detection and ensure that no person or object enters the boundary of the machine’s movement. Point of operation guards are installed at the site of material handling or the pinch point. Light curtains used in point of operation guarding are selected for finger and hand detection and are used in applications such as hydraulic presses, riveting, stamping and automated assembly machinery.