US 7,508,512 B1
Continuous optical self-alignment for light curtains and optical presence sensors for simplification and maintenance of alignment
George E. Rollins, Chelmsford, Mass. (US); James E. Dogul, Hudson, N.H. (US); Richard Galera, Nashua, N.H. (US); Derek W. Jones, Kirkcudbright (United Kingdom); George Schuster, Royal Oak, Mich. (US); Suresh Nair, Amherst, N.H. (US); and Ray Delcher, Oxnard, Calif. (US)
Assigned to Rockwell Automation Technologies, Inc., Mayfield Heights, Ohio (US)
Filed on Feb. 23, 2006, as Appl. No. 11/360,176.
Int. Cl. G01B 11/00 (2006.01); G02F 1/1345 (2006.01)
U.S. Cl. 356—399  [356/121; 356/138; 356/432; 349/139] 14 Claims
OG exemplary drawing
 
1. A system that facilitates correcting misalignment in a light curtain, comprising:
a back-lit LCD that selectively permits light from an emitter to pass through transmissive apertures generated on the LCD;
a first lens that focuses light that has passed through the transmissive apertures on the back-lit LCD to generate the light beam that traverses a monitored area;
a second LCD that selectively permits a light beam that has traversed the monitored area to pass through transmissive apertures generated on the second LCD to a receiver;
a second lens that re-focuses the light beam at an opposite side of the monitored area prior to passing through the transmissive apertures on the second LCD; and
a control component that provides feedback information to at least one of the LCDs to adjust a position of the transmissive apertures generated thereon when the light beam is determined to be misaligned.