Abstract: A latch mechanism for a small-size printer capable of performing a printing operation with a desired type on a rotatable type drum being held at a print position by impacting a hammer towards the type drum across a recording paper loaded therebetween. The latch mechanism comprises a group of type drums composed of type drums of three digits each comprising a lock groove wheel for fixing one type drum selected among three drums at a print position by one type selection operation; a group of lock levers movable between its initial non-print position and its print position, which is disposed so as to correspond to each of the type drums, and constantly biased by a lock lever spring toward the lock groove wheel to lock the type drum in a print position; and a group of lock lever holding means capable of actuating the lock lever by being attracted by an electromagnet.

Abstract: A printer device having a hammer mechanism for printingly impacting a type drum by means of hammer springs. Hammers are rotatably controlled to retracted positions where the hammers are not brought into contact with a reset cam in each printing cycle, so that unnecessary contact between the hammers and the reset cam can be eliminated, frictional loss and noise can be reduced. The hammers are temporarily reset to first retracted positions upon completion of printing, and thereafter, turned to the aforesaid second retracted positions.The release of locking of the hammers is effected by feeding a printing command to electromagnetic means, whereby an armature of the electromagnetic means moves hammer holding members to thereby release locking of the hammers.

Abstract: In a governor device for a printer including a driving wheel rotating for a predetermined amount by means of urging force by a urging spring to feed paper and engaging with a stopper to stop at this position and a governor gear train consisting of a speed-up gear engaged with the driving wheel and a fly wheel to perform the governing action. The governor device for a printer further includes a wind-up gear engaging with the driving wheel and a friction slip device attached to the fly wheel in the governor gear train to absorb the bounce when the driving wheel stops.

Abstract: A print hammer driving means for impact printers comprising a type drum having a plurality of circumferentially arranged type characters, a plurality of print hammers and a hammer spring for moving each print hammer to the type drum for printing, a wind-up lever engaged with the print hammer for winding the hammer spring, a snatch roll for actuating the wind-up lever and an electromagnet adapted to engage the wind-up lever with the snatch roll. The wind-up lever and the snatch roll are so arranged as to engage with each other during the wind-up period in one printing cycle and to release the print hammer after the wind-up period for printing.