Light curtain

Light curtains, now more commonly known as opto-electronic devices, are used to safeguard personnel in the vicinity of moving machinery with the potential to cause harm such as presses, winders and palletisers.

Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine the means being photocells or other devices sensitive without mechanical contact using light grids[1]A year later, he followed up by also applying his patent idea in China, Italy, Japan, United States, Sweden and Great Britain.

This invention substantially lowered the costs of safeguarding personnel without adversely affecting the high requirements of reliability and safety which were until than relied upon such screens.

Other common presence detection devices are pressure-sensitive safety mats and laser scanners (often used on Remotely Operated Vehicles (ROV) when in industrial settings).

Typically, light curtains are connected to a safety relay which will remove motive power from the hazard in the event that an object is detected.