Importance

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Abstract

A system for detecting a flame or droplets of burning polypropylene in an area below an upper surface of a conventional wet bench used in semiconductor production includes at least one sensor, a threshold detector, a discrimination, a counter and a latch. The sensor detects radiation generated by activity in the area and for generating a sensor signal in response to the detected radiation. The threshold detector determines whether the activity has a cross-sectional area which exceeds a predetermined threshold area. The discriminator determines whether the activity displays a flicker rate or a droplet rate that is within the predetermined flicker rate range. The counter determines whether a predetermined number of flickers or droplets has been detected within a predetermined time period, and the latch asserts a true output signal when the detected activity exceeds the predetermined threshold area, the flicker rate or the droplet rate is within the predetermined flicker rate range, and a predetermined number of flickers or droplets have been detected within the predetermined time period.

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First Claim