The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 12, 1992
Filed:
Mar. 18, 1991
Carl-Zeiss-Stiftung, Heidenheim, DE;
Abstract
The invention is directed to a protective arrangement for a longitudinally extendible machine component such as a measuring arm of a machine such as a coordinate measuring apparatus. The protective arrangement includes a light barrier unit having a response sensitivity and including a light source for directing a light beam parallel to the axis of the machine component as well as first and second detectors for receiving first and second portions of the light beams and for supplying first and second signals indicative of the intensities of the portions of the light beam. The light source and the detectors are mounted on the machine component so that the length of the light beam between the source and the detectors and the respective light intensities received by the detectors change in correspondence to the distances as the machine component is extended or retracted. A structure shades the light beam in response to a contact engagement of the structure with an object or person. A comparator circuit compares the signal of the detectors and remains nonconductive so long as the light intensities uniformly increase or decrease with changes in the above-mentioned distances. The comparator circuit provides an output signal for bringing the machine component to standstill in response to uneven changes in the light intensities received by the detectors relative to each other when the beam becomes shaded. In this way, a control unit of the machine can, for example, initiate an emergency stoppage of the machine component thereby preventing injury to personnel or damage.