OPTICAL SAFETY DEVICE FOR PRESS BRAKES, PRESS BRAKE, AND OPTICAL MONITORING METHOD

摘要

In the present invention, an assessment unit (70) assesses, on the basis of the light reception state of a photodiode (564) positioned nearest an upper die (12), whether or not a shadow of the upper die (12) cast by a laser (B) projected on an optical receptor (52) side has expanded to the photodiode (564). A deactivation unit (72) deactivates the photodiode (564) positioned nearest the upper die (12) if it is determined that the shadow of the upper die (12) has expanded to said photodiode (564). A detection unit (74) detects the presence or absence of foreign matter between the upper die (12) and a lower die (14) on the basis of the light reception state of a plurality of active photodiodes (56) while an upper table (26) is descending.