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Light curtain has `world`s first position-based muting function`

01 January, 2006

Light curtain has `world`s first position-based muting function`

Omron has announced a safety light curtain which, it claims, can distinguish between an operator who is temporarily blocking a detection zone to install a workpiece, or one who has entered a hazardous area by mistake.

Traditionally it has been difficult to use light curtains for applications where operators need to install workpieces in machinery. Omron claims to have overcome this limitation by combining a muting function (which disables the light curtain temporarily when a workpiece or other item passes thought its detection zone) with position detection.

Instead of determining when to start and end muting by detecting the presence of a workpiece or person, the new muting function uses a limit switch or sensor to determine whether the machinery (or a robot) is in a safe position or is stopped, or whether the machine is moving and is posing a hazard. This makes it possible to disable the light curtain only when the equipment is safe.

Omron claims that its F3SJ-A light curtain is also the first to split its detection zone into two areas - a warning area and a stop area. The curtain can be installed horizontally so that as a person approaches a dangerous area, the safety system first raises an alarm and stops the machine only if the person moves further into the danger zone. This facility is expected to reduce the number of nuisance stops caused by light curtains.

Another function allows specified optical beams to be disabled by muting, keeping others active, even during muting. This partial muting function is said to minimise the risk of being unable to detect human entering a danger area at the same time as a workpiece is moving.

The light curtain also has a blanking function that can disable detection for beams that are blocked constantly, and can turn off the safety output even when more than a specified number of beams is obstructed. This is designed to overcome the problem of installations where parts of a machine are always inside the curtain`s detection zone. In such cases, it may be impossible to start the machine because the continuous obstruction of some of the beams means that safety output is continuously off.

The new light curtains, which will be produced in various heights, beam gaps and detection distances, will be available initially only in Japan. Omron expects to sell around 50,000 of them in the first year.

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