Three-position ribbon guide for printer

Claim 2

A ribbon guide bar for a printer assembly comprising a pair of armature levers carried pivotally on pins spaced transversely to an axis of said guide bar in a horizontal, center position for movement in a plane formed by said guide bar, each said lever being actuated by an electromagnet in one direction and by a spring in an opposite direction and carrying at an end thereof a coupling pin, the ribbon guide bar being pivoted at one end about an axis parallel to said armature lever pins and carrying a ribbon guide at an opposite end and comprising: a pair of guide slots formed in said bar between said ends, spaced apart transversely of said guide bar axis, each said slot slidably but snugly receiving one of said coupling pins of said levers and comprising a first, generally vertical portion having an end spaced adjacent said guide bar axis, and second horizontal portion extending parallel to said guide bar axis and having an end coinciding with said end of said first slot portion, whereby each coupling pin may travel freely between said first and second guide slot portions, whereby said guide bar may be locked in any of three positions by said coupling pins in said guide slots depending upon actuation of said electromagnets.

Claim 3

A ribbon guide bar as defined in claim 1, wherein the first, generally vertical portion of each of said guide slots has a radius of curvature equal to a distance from its median to said guide bar pivot axis.

Claim 4

A ribbon guide assembly for a printer comprising: a ribbon guide bar mounted upon a horizontal pivot axis in one end thereof in said printer, said guide bar having a ribbon guide at an opposite end and a pair of guide slots arranged symmetrically of said guide bar about an axis of said bar, each said guide slot having a width and a first, generally vertical portion transverse to said bar axis, and a second, straight portion having a first end coinciding with an end of said first, vertical portion nearer said bar axis, the second portion extending parallel to said bar axis and spaced therefrom; a pair of armature levers arranged transversely to said ribbon guide bar axis in a centered position thereof, said levers each comprising a lever pivot axis spaced a distance from said guide bar axis and parallel to said guide bar pivot axis, a coupling pin in an end of said lever, said pin riding in a nearer one of said guide slots of said ribbon guide bar and having a diameter slightly less than the width of said guide slot, and a magnetic armature fixed in said lever and spaced adjacent said lever pivot axis; a pair of electromagnets each fixed in said printer upon a magnet axis parallel to said guide bar axis in said centered position of said guide bar and in a position to magnetically attract a corresponding one of said armatures in said levers; and a pair of return springs each engaging one of said levers to act thereon in opposition to a corresponding one of said electromagnets, whereby actuation of one of said magnets moves the guide bar to a first position, actuation of the other of said magnets moves the guide bar to a second position, and actuation of neither magnet leaves the guide bar locked in a third, centered position.

Claim 5

A ribbon guide assembly for a printer comprising: a ribbon guide bar mounted upon a horizontal pivot axis in one end thereof in said printer, said guide bar having a ribbon guide at an opposite end and a pair of guide slots arranged symmetrically of said guide bar about an axis of said bar, each said guide slot having a width and a first, generally vertical portion transverse to said bar axis, and a second, straight portion having a first end coinciding with an end of said first, vertical portion nearer said bar axis, the second portion extending parallel to said bar axis and spaced therefrom; a pair of armature levers arranged transversely to said ribbon guide bar axis in a centered position thereof, said levers each comprising a lever pivot axis spaced a distance from said guide bar axis and parallel to said guide bar pivot axis, a coupling pin in an end of said lever, said pin riding in a nearer one of said guide slots of said ribbon guide bar and having a diameter slightly less than the width of said guide slot, and a magnetic armature fixed in said lever and spaced adjacent said lever pivot axis; a pair of electromagnets each fixed in said printer upon a magnet axis parallel to said guide bar axis in said centered position of said guide bar and in a position to magnetically attract a corresponding one of said armatures in said levers; and a pair of return springs each engaging one of said levers to act thereon in opposition to a corresponding one of said electromagnets, whereby actuation of one of said magnets moves the guide bar to a first position, actuation of the other of said magnets moves the guide bar to a second position, and actuation of neither magnet leaves the guide bar locked in a third, centered position.

Claim 6

A ribbon guide assembly as defined in claim 3, wherein each of said return springs engages its corresponding lever opposite said lever pivot axis from said coupling pin.

Claim 7

A ribbon guide assembly as defined in claim 3, wherein each said armature is located between said lever pivot axis and said coupling pin.

Claim 8

A ribbon guide assembly as defined in claim 3, wherein each said return spring has a steep characteristic curve of spring force versus displacement.