Differential lever actuator including differentially force- transmitting members which are not liable to break

摘要

In a differential lever actuator comprising transmission members (41, 42) for differentially transmitting oppositely sensed angular displacements from first and second weight points (P1, P3) of first and second lever members (31, 32) to first and second predetermined points (P2, P4) of a differential lever member (41), a distance between midpoints (S, T) between the first weight and predetermined points and between the second weight and predetermined points is kept constant irrespective of the angular displacements. Preferably, at least one transmission member should be perpendicular to a line passing through the related weight point and a fulcrum point (Q or R) of the associated one of the first and second lever members. When carried by the differential lever member for print of a dot, a rod should preferably have an axis passing through a point of intersection of the transmission members. Alternatively, the differential lever member should have a center of a rotational component of the distance (ST) at a point of percussion related to a reaction resulting from print of the dot. As a further alternative, at least one transmission member should be thicker than 0.05 times a length between the related weight and predetermined points.