Serial impact calculator printer
AssigneeLRC, Inc.
InventorNicholas Kondur, Jr.
Life of this patent
Estimating the term…
Abstract
A serial impact printer of the type utilizing a dot matrix print head is specifically adaptable for use as a calculator or adding machine and is characterized by utilizing a common drive source to advance the print head across the paper, advance the paper between printing operations, and selectively advance the print ribbon between the ribbon supply spool and takeup spool. An improved paper-advancing means has been devised which operates in close correlation with the print head drive member to provide a relatively high speed, simplified and inexpensive printer unit; and the ribbon supply spools are so constructed and arranged as to be interchangeable and to permit direct drive through a spool-engaging member on the print head whereby to advance the ribbon in direct response to print head travel.
Claims9
In a printing apparatus having a frame, a print head selectively actuated by actuating means associated with said head to impress characters on a recording medium, a pair of record medium advancing rollers mounted for rotation on spaced parallel axes with the external roller surfaces engageable with one another to define a common guide path for advancement of the recording medium therebetween and advancing means associated with said print head drive means to incrementally drive one of said print medium advancing rollers in a direction causing advancement of the recording means, the improvement comprising:
- print head drive means rotatable to reversibly drive said print head in a print and return direction transversely of the direction of advancement of the recording medium,
- a pair of ribbon spools disposed for rotation at opposite ends of travel of said print head, a print ribbon wound on said spools for passage between said print head and recording medium, each spool including ratchet means thereon to cause each spool to undergo rotation when said ratchet means are positively advanced, and
- ratchet drive means pivotally mounted on said print head for travel therewith, said ratchet drive means alternately movable into engagement with one of said spools to wind said printing ribbon onto one spool and responsive to resistance of the one spool to rotation to pivot away from engagement with the one spool and into engagement with the other spool to reverse the travel of said printing ribbon whereby to unwind it from the one spool and wind it onto the other spool.
A printing apparatus comprising in combination:
- a frame including spaced-apart, upright side frame portions and a horizontal bed extending between said side frame portions and rigidly interconnecting said side frame portions,
- a motor drive assembly affixed to one of said side frame portions,
- a paper supply roll disposed between said side frame portions rearwardly of said horizontal bed,
- paper advancing means including a platen journaled between said side frame portions above and in closely spaced relation to a concave guide surface at the rearward end of said bed so as to form an arcuate guide path between said platen and said concave guide surface,
- a pressure roll seated in a recess disposed in said bed forwardly of said concave guide surface, means yieldably supporting said pressure roll in said recess whereby to yieldingly urge said pressure roll against the external surface of said platen,
- a detent engaging ring at one end of said platen mounted for rotation therewith and provided with a plurality of circumferentially spaced detent engaging grooves along its outer peripheral surface,
- a ratchet member at one end of said platen opposite to said detent engaging ring mounted for rotation therewith and provided with a plurality of circumferentially spaced ratchet teeth on its outer peripheral surface,
- a print head including a head carrier, a print head drive member journaled for rotation between said side frame portions in a recess formed in said horizontal bed forwardly of said platen and said pressure roll, said print head drive member including an outer cylindrical surface provided with a helical groove therein, rotatable drive means between said motor drive and said print head drive member operative to rotate said drive member at a predetermined rate of speed whereby to reversibly drive said print head in a print and return direction transversely of the direction of advancement of the paper forwardly along said arcuate guide path and upwardly between said pressure roll and said platen,
- a detent member mounted for limited rotation at one end of said platen adjacent to said detent engaging ring, said detent member including a detent arm movable into engagement with one of said detent engaging grooves and a manual release level engageable to release said detent arm from engagement with said detent engaging ring, and means normally urging said detent arm in a direction forcing it into engagement with one of said detent engaging grooves,
- incremental drive means for said platen including an eccentric member mounted for rotation with said print head drive means and a ratchet drive arm journaled for rotation on said eccentric member and extending rearwardly therefrom, said ratchet drive arm including a pawl at its rearward distal end movable into and away from engagement with one of the ratchet teeth on said ratchet wheel in response to rotation of said eccentric member whereby to advance said platen a predetermined distance as said print head is driven in the return direction, and
- a pair of ribbon spools disposed for rotation at opposite ends of travel of said print head, a print ribbon wound on said spools for passage between said print head and the path of advancement of said paper above said pressure roll, and ribbon spool drive means between said head and said ribbon spool, said ribbon spool drive means being responsive to resistance of rotation of each spool to rotation to move into driving engagement with the other spool for reversibly advancing said print ribbon back and forth between said ribbon spools in response to travel of said print head.
Dependencies are inferred from the claim text.