Dot printer

Claim 2

A dot printer comprising: a. a plurality of plungerless electromagnets of the clapper type each comprising a yoke formed of flat sheet material, a core secured to said yoke, a coil wound on the core, an armature having a base and an opposite free end, and non-resilient means for pivotally connecting the armature base to the yoke to allow pivotal movement of the armature toward and away from the core but to prevent movement of the armature transversely of the core axis, said base overlapping the yoke and maintaining contact with a continuous line thereof at all times, said opposite free end of the armature tapering in going from the base toward the free end, said armature being disposed substantially transversely of the core axis, said plurality of electromagnets being disposed radially to form a circle with the free ends of the armatures being disposed toward the center of the circle, said core having a triangular cross-section with an apex pointing to the center of the circle, b. a plurality of needes for performing dot printing corresponding in number to the plurality of electromagnets, each of said needles having a free end and a base, and the needles being respectively operatively connected at their bases to the free ends of the armatures of the respective electromagnets, c. resilient means for urging the armatures of the electromagnets to move away from the cores when the electromagnets are inoperative, and d. guide means for guiding the needles to cause the free ends thereof to be aligned with one another and disposed in a row in face-to-face relationship with a recording sheet, said electromagnets being selectively magnetized and rendered operative for selective actuation of the needles to perform dot printing on the recording sheet by selective passage of current to the coils of the electromagnets respectively associated with the needles to be selectively actuated.

Claim 3

A dot printer as set forth in claim 1 wherein said means for urging the armatures of the electromagnets to move away from the cores when the electromagnets are inoperative comprises a plurality of plate springs each mounted between the armature and yoke of one of the electromagnets.

Claim 4

A dot printer as set forth in claim 1 wherein said means for urging the armatures of the electromagnets to move away from the cores when the electromagnets are inoperative comprises a plurality of coil springs each mounted on one of the needles.

Claim 5

A dot printer as set forth in claim 1 further including a carriage, a pin supported by said carriage, and a feed screw rotatable at a uniform rate, said electromagnets being mounted on said carriage together with said needles which are connected to the respective electromagnets, and said pin being adapted to be brought into and out of engagement with said feed screw during rotation of the screw at a uniform rate to move the carriage axially of the feed screw whereby the needles can be moved in a recording direction.

Claim 6

A dot printer as set forth in claim 4 further including a solenoid for driving said pin to bring said pin into and out of engagement with said feed screw.

Claim 7

A dot printer comprising: a. a plurality of plungerless clapper-type electromagnets each comprising a yoke formed of flat sheet material, a core of triangular cross-section mounted thereon, an energizable coil wound on the core, an armature having a base and an opposite free end and disposed substantially transversely of the core axis, non-resilient means for pivotally connecting the armature base to the yoke to allow said free end of the armature to move toward and away from the core along the core axis but to prevent movement of the armature transversely Of the core axis, said base overlapping the yoke and maintaining contact with a continuous line thereof at all times, said electromagnets being disposed in a circle with the armature free ends oriented toward the center of the circle and with the apices of the core cross-sections pointing to the center of the circle; b. means for resiliently biasing the armature free end of each electromagnet away from the core thereof such that the armature free end moves toward and away from the core in correspondence with energization and de-energization, respectively, of the coil wound on the core; c. a plurality of needles, equal in number to the electromagnets, each having a free end and respectively operatively interengaged with the armature free ends of the respective electromagnets for movement therewith such that the free end of each needle is advanced and retracted in correspondence with movement of its associated armature free end toward and away from its associated core, respectively; and d. guide means for aligning the free ends of the needles in a straight row and for guiding each needle free end, in its position in said row, to produce a dot imprint on a recording medium upon advance of the needle free end as aforesaid, said electromagnet coils being selectively energizable for effecting selective advance of particular ones of said needles to produce on the recording medium a predetermined dot imprint pattern.

Claim 8

A dot printer comprising: a. a plurality of plungerless clapper-type electromagnets each comprising a yoke formed of flat sheet material, a core of triangular cross-section mounted thereon, an energizable coil wound on the core, an armature having a base and an opposite free end and disposed substantially transversely of the core axis, non-resilient means for pivotally connecting the armature base to the yoke to allow said free end of the armature to move toward and away from the core along the core axis but to prevent movement of the armature transversely Of the core axis, said base overlapping the yoke and maintaining contact with a continuous line thereof at all times, said electromagnets being disposed in a circle with the armature free ends oriented toward the center of the circle and with the apices of the core cross-sections pointing to the center of the circle; b. means for resiliently biasing the armature free end of each electromagnet away from the core thereof such that the armature free end moves toward and away from the core in correspondence with energization and de-energization, respectively, of the coil wound on the core; c. a plurality of needles, equal in number to the electromagnets, each having a free end and respectively operatively interengaged with the armature free ends of the respective electromagnets for movement therewith such that the free end of each needle is advanced and retracted in correspondence with movement of its associated armature free end toward and away from its associated core, respectively; and d. guide means for aligning the free ends of the needles in a straight row and for guiding each needle free end, in its position in said row, to produce a dot imprint on a recording medium upon advance of the needle free end as aforesaid, said electromagnet coils being selectively energizable for effecting selective advance of particular ones of said needles to produce on the recording medium a predetermined dot imprint pattern.

Claim 9

A dot printer as defined in claim 6, wherein said biasing means for each electromagnet comprises a plate spring acting between the yoke and armature of the electromagnet, and wherein each of said needles has a base secured to the free end of the armature with which it is operatively interengaged.

Claim 10

A dot printer as defined in claim 6, wherein each of said needles has an enlarged base bearing against the free end of the armature with which it is operatively interengaged, and extends therefrom through said guide means, and further including fixed structure through which said needles movably extend intermediate said armatures and said guide means, and wherein said biasing means comprises a plurality of helical springs respectively surrounding said needles, each of said springs being under compression between the base of the needle it surrounds and said fixed structure for urging the needle into a retracted position.