Abstract: A forearm lifter for assisting in the articulation of a mating forearm part of an arm prosthesis with respect to a mating upper arm part about at least one elbow axis is disclosed. The forearm lifter includes: (i) a spring element; (ii) a mechanism having an input and an output, with the spring element directly or indirectly applying a tensile force to the input of the mechanism; and (iii) a tension element having one end acted upon by the output of the mechanism, and having another end which can be fastened at a fixed point on said mating upper arm part. The fixed point and the elbow axis define a torque lever, such that the force that is transmitted through the mechanism from the spring element applies torque to the mating upper arm part in such a manner that the curve of the torque acting at the fixed point, plotted against the angle of articulation of said forearm part, is approximately parabolic. The torque has its minimum values in both the forearm extended position and at maximum forearm bending.

Abstract: A film strip is continuously advanced past a film gate of a camera or a projector while light coming from the strip through the film gate is reflected by a pivotable mirror keeping a beam of light trained upon a specific area of the strip, i.e., a frame, during a major part of a recurrent operating cycle. The mirror is reciprocated during each operating cycle under the control of an electrical signal generator synchronized with the strip-feeding mechanism, either directly or through markings (e.g., perforations) on the film strip, and performs a relatively slow forward sweep followed by a relatively fast return sweep, the latter being effected by a pulse of one polarity immediately followed by a pulse of opposite polarity arresting the mirror drive. In one embodiment (FIG.