Inventor

LETZEL HELMUT

DE3 patents

Patents

3 patents

US6539760B1Apr 1, 2003

Monitoring device

SCHMERSAL K A GMBH & CO28 citations89

US6283514B1Sep 4, 2001

Apparatus for monitoring and controlling access to a restricted area

SCHMERSAL K A GMBH & CO26 citations87

US5896783AApr 27, 1999

Safety switch device

SCHMERSAL K A GMBH & CO4 citations57