Dot matrix print actuator

DETAILED DESCRIPTION The present invention is directed to an improved actuator of the stored energy type.
The actuator assembly incorporates numerous features which improve the performance and efficiency of the mechanism.
Broadly, the actuator incorporates upper and lower sets of hammer elements and corresponding magnetic circuits with the free ends of the hammer elements being interleaved so that the impact tips of both the upper and lower sets lie along a common print line.
The interleaved structure reduces interaction between the magnetic circuits of adjacent printing positions while at the same time providing a compact structure.
In operation, the printhead is carried so that the impact tips lie along a line which is slanted with respect to the printing line.
An entire character is printed with each pass of the printhead, thereby avoiding any problems of misregistration between different rows of the matrix.
In another aspect of the invention, each magnetic circuit includes a pair of pole elements which are positioned so that their faces contact the hammer element when the hammer is retracted.
This construction serves to aid in the damping of the hammer elements to thereby enable faster cycling times to be achieved.
More specifically, the pole pieces are positioned so that they contact the hammer at points corresponding to anti-nodes of various modes of vibration of the hammer.
The pole pieces thus provide physical obstructions which prevent the hammer from vibrating.
In accordance with another aspect of the invention, the spring hammer elements are angled with respect to the pole pieces and mounting assembly so that the impact tips extend beyond any other portion of the assembly.
This structure facilitates convenient paper and ribbon motion.
In accordance with yet another aspect of the invention, the pole pieces are formed of a plurality of laminations and are connected to a common member.
This structure increases the efficiency of the magnetic circuits by reducing eddy currents.
In accordance with yet another aspect of the invention, a cooling structure is formed integrally with the coil means