A manually fed machine for working on materials, objects and the like, and protective means for such a machine

摘要

A manually fed machine for working on materials, objects or the like, in particular a circular saw or a band saw bench, a planing bench, a bench drill, a press, or scissors, comprises a working tool (14), a feeding area (18) in front of the tool (14), within which a person's hand is present when feeding material to be worked on to the tool (14), and a detector (24) covering at least a section (22) of the feeding area (18) for a contactless detection of human skin. The detector (24) comprises at least one set of at least two transmitter diodes (32,34), and at least one receiver diode (36), the at least two transmitter diodes (32,34) emitting radiation towards said section (22) of the feeding area (18), said radiation being emitted at at least two different transmission wavelengths in the wavelength range between 400 nm and 1500 nm, wherein at least one of the transmitter diodes (32,34) radiates in the wavelength range between 900 nm and 1500 nm, whereas the at least one receiver diode (36) receives the radiation reflected from the section (22) of the feeding area (18). The manually fed machine is further provided with a signal evaluation unit (38) connected with the detector (24) for evaluating the intensity of the reflected radiation from the transmitter diodes (32,34) received by the receiver diode (36). The signal evaluation (38) unit determines from the intensities of the reflected radiation from the transmitter diodes (32,34), whether the detector (24) detects human skin. Upon the detection of human skin, a protective means (28) may be activated for protection against potential injuries caused by the tool (14).