US 4,518,887 AGranted

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

AssigneeNEC Corporation

InventorsTakeshi Yano, Izumu Fukui, Takeshige Hamatsuki, Eiichi Sato, Osamu Inui

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Abstract

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.

In a differential lever actuator comprising a driving member having an axis, a first end fixed to a base member, and a second end susceptible to a linear displacement along said axis, first and second lever members attached to said base member at first and second fulcrum points, respectively, and to said second end at first and second power points, respectively, first and second plate-shaped resilient power transmission members having principal surfaces perpendicular to a reference plane including said axis and said first and said second power points and attached to said first and said second lever members at first and second weight points, respectively, and a differential lever member carried by said first and said second transmission members at first and second predetermined points, respectively, wherein said first and second fulcrum points, said first and second power points, said first and second weight points, and said first and second predetermined points are arranged to satisfy the following equation:

##EQU5## where e:
the distance between the first and second fulcrum points
f:
the distance between the first fulcrum point and the midpoint between the first weight point and the first predetermined point (first midpoint)
g:
the distance between the second fulcrum point and the midpoint between the second weight point and the second predetermined point (second midpoint)
.0.(e,f):
an angle which is measured counterclockwise from the line including the first and second fulcrum points to the line including the first fulcrum point and the first midpoint
.0.(e,g):
an angle which is measured counterclockwise from the line including the first and second fulcrum points to the line including the second fulcrum point and the second midpoint
.0..sub. :
an increment angle added to the angle .0.(e,f)
.0..sub.2 :
an increment angle added to the angle .0.(e,g)
.0..sub.2 /.0..sub.1 =l.sub.1 /l.sub.2
where
l.sub.1 :
the distance between the first fulcrum point and the first power point
l.sub.2 :
the distance between the second fulcrum point and the second power point.

17 more elements

Abstract

Claims12