Print wire drive assembly for dot-matrix printers

Claim 1

A print wire drive assembly for a dot-matrix printer having a plurality of print wires selectively driven to impact a printing surface for impression of characters on the printing surface, said print wire drive assembly comprising: a plurality of electromagnetic solenoids provided, in a plurality of groups which are not energized simultaneously, to drive corresponding plural groups of said print wires, at least one of said solenoids of one of said groups being spaced from at least one of said solenoids of another group adjacent said one group by a distance shorter than a distance by which any of the other solenoids of said one group is spaced from any of the other solenoids of said another group; and a solenoid drive circuit including a first connection line by which a high-level terminal of said at least one solenoid of said one group is connected to a low-level terminal of said at least one solenoid of said another group, and a second connection line by which a low-level terminal of said at least one solenoid of said one group is connected to a high-level terminal of said at least one solenoid of said another group, at least one of said first and second connection lines comprising a rectifying element allowing a current flow from said low-level terminal to said high-level terminal through the connection line while inhibiting a current flow therethrough from said high-level terminal to said low-level terminal, said connection lines supplying to said at least one solenoid of said one group a current which is generated owing to a back electromotive force of said at least one solenoid of said another group when said at least one solenoid of said one group is energized immediately after said at least one solenoid of said another group has been deenergized, said current partly energizing said at least one solenoid of said one group to the extent that will not cause the respective print wire to be driven.