STI: Safety laser scanners guard areas near machines

By Control Engineering Staff October 27, 2005

A safety laser scanner, among newest technologies to be used for machine area safeguarding, uses a small optical sensor, pulses laser light to monitor surroundings, compares results to a predefined zone, and sends a stop signal to connected machinery when an intrusion is detected, according to Scientific Technologies Inc.

Its advantage over other technologies, STI says, is “versatility and non-intrusive presence.” Unlike hard guards such as fences or safety floor mats, the laser scanner works without physical barriers so is perfect for equipment that requires regular maintenance and cleaning. “Fewer hardguards are needed, allowing sweepers, forklifts, and loaders to transit through its protection area.”

STI explains that “Safety laser scanners function by using a‘time of flight’ measurement to determine distance. The scanner emits a light pulse; the light then hits the first object in its path and is reflected back to the scanner. Then the scanner compares the distance against the known size of its safety zone. If the scanner senses an intrusion into the safety zone, it sends a stop signal to the guarded machinery. This sequence is repeated as the optical assembly rotates, scanning the guarded area.”

The advice came in STI’s 850-page “2006-2007 Engineering Guide to Machine and Process Safeguarding,” which includes tutorial information and product examples for safety laser scanners, perimeter access guards, safety light curtains, resource modules, safety mats and area guards, safety interlock switches, and safety monitoring relays. Hydraulic press-brake guards, safety contact strips and edges, two-hand controls, enabling switches, and process safeguards are also featured. New product categories include safety awareness signs, disconnect switches and motor starters, as well as cutting and turning machine safety.

—Mark T. Hoske, editor-in-chief, Control Engineering,