US 5,113,759 AGranted

Latch mechanism for small-size printer

AssigneesCitizen Watch Co., Ltd., Astec, Inc.

InventorShohachi Nihira

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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. Thus, since the lock groove wheel of each type drum has a predetermined alignment, it is possible to select on desired type drum from a plurality of type drums by one type selection operation. By a repetition of this type selection operation, the types of plural digits can be selected by a single electromagnet.

Claims18

Dependent claims

A latch mechanism for a small-size printer capable of performing a printing operation with a desired type on a rotatably type drum secured at a print position by impacting a hammer towards the type drum across a recording paper loaded therebetween, said latch mechanism comprising:

a type drum shaft;
a plurality of type drum units, each of which include lock groove wheels and font wheels disposed in spaced relation to each other, said font wheels having a plurality of characters and symbols on their outer peripheral, and rotating with said type drum shaft and means to latch said font wheels to position a desired type for printing;
a plurality of lock lever units, each of which includes a plurality of lock lever means for latching a desired lock groove wheel in the print position when performing an printing operation and for latching a font wheel at said font wheel's initial non-print position, and disposed so as to correspond to each type drum, and movable between a print position and an initial non-print position;
a lock lever spring means for constantly providing a biasing force that biases said lock lever means from said lock lever means initial non-print position toward a print position where said lock lever means latches said type drum;
a plurality of lock lever holding means units, each of which includes a plurality of lock lever holding means with a holding side and a locking side for respectively holding said lock means in their initial non-print positions remote form said font wheels in a non-printing state and for releasing said lock lever means from their initial nonprint positions by being actuated downwardly;
a plurality of vibration plates, each of which is provided so as to correspond to each of said lock lever holding means units for actuating said lock lever holding means;
a plurality of electromagnets, each of which is provided so as to correspond to and activate one of said vibration plates;
and
a reset bar means for resetting said plurality of lock levers means from their print positions to the initial non-print positions after a printing operation is completed.

6 more elements

A latch mechanism for a small-size printer capable of performing a printing operation with a desired type on a rotatable type drum secured at a print position by impacting a hammer towards the type drum across a recording paper loaded therebetween, said latch mechanism comprising:

a type drum shaft;
a plurality of type drum units, each of which includes lock groove wheels and font wheels disposed in spaced relation to each other, said font wheels having a plurality of characters and symbols on their outer peripheral, and rotating with said type drum shaft and means to latch said font wheels to position a desired type for printing;
a plurality of lock lever units, each of which includes a plurality of lock lever means for latching a desired lock groove wheel in the print position when performing a printing operation and for latching a font wheel at said font wheel's initial non-print position, and disposed so as to correspond to each type drum, and movable between a print position and an initial non-print position;
a lock lever spring means for constantly providing a biasing force that biases said lock lever means from said lock lever means initial non-print position toward a print position where said lock lever means latches said type drum;
a plurality of lock lever holding means units, each of which includes a lock lever holding means which is a single plate with a holding side and a locking side for respectively holding said lock lever means in their initial non-print position remote from said font wheels and for releasing said lock lever means from the non-print position by being attracted downwardly;
a plurality of electromagnets, each of which is provided so as to correspond to and one of said lock lever holding means;
and
a reset bar means for resetting said plurality of lock lever means from their print position to the initial non-print position after a printing operation is completed.

5 more elements

Dependencies are inferred from the claim text.