GB903116A - Improvements in linkages producing straight line motion - Google Patents

Abstract

903,116. Windscreen wiper mechanisms. PARSONS, R. July 10, 1959 [Sept. 5, 1958], No. 28542/58. Class 138 (1). [Also in Groups XX and XXIV] In linkwork ensuring that a device, such as a camera, lamp, lens, pen or windscreen wiper, carried by a bracket 26 moves only in a straight line and remains parallel to itself, the bracket 26 is supported from a bracket 18 on a fixed stand 19 by two pairs of equal length parallel rods 15, 16 and 24, 25 pivoted on an intermediate member 21, the rods 16, 24 being coupled by means such as gear segments 29 so that they move through equal angles in opposite directions. Alternatively or additionally the rods 15, 25 may be similarly coupled. A spring 31 may be provided between rods 15, 25 to counterbalance the member 21. Alternatively counterweights or frictional joints may be employed. As shown, the bracket 17 is fixed to a tube 18 clamped to the stand 19, and the bracket 26 has a tube 27 for carrying a lens. Alternatively the bracket 18 may be rotatable on the stand 19 and rest against an adjustable collar thereon so that the lens may be traversed in a plane parallel to a surface 30 to be examined. To avoid interference between the rods when brought together the line joining the pivots on the bracket 17 is is inclined to the vertical. The two pairs of rods may be in different planes to allow them to pass one another. In a modification, the gear segments 29 are replaced by discs 37, 38, Fig. 4, on the ends of the rods 16, 24, the two discs being coupled by a strip of material or by intermeshing nylon threads 39, 42 attached to and wrapped around the discs. In a further modification dispensing with the gear segments 29 the rods 16, 24, Fig. 3, have a common pivot 34 on the member 21 and are coupled by links 36, 35, respectively, parallel to the rods. Means may be provided to reciprocate the bracket 26.