Abstract: A dot matrix print head has a temperature sensor for detecting the temperature of the print head itself. When the detected temperature exceeds a preset temperature, the temperature sensor produces and output signal for stopping or slowing down the dot matrix print head so that its temperature may be lowered. The temperature sensor is accommodated in a substantially central hole of a radial member mounted in a heat conductor body and having a plurality of circumferentially spaced heat conducting arms with their radially outer ends held intimately against the radially inner surfaces of driver or demagnetizing coils which actuate dot pins. The heat conducting arms can quickly and accurately conduct the heat from the coils to the temperature sensor.

Abstract: A connector housing has an insertion slot for receiving a companion base board, a plurality of grooves defined in a housing bottom in a direction normal to the insertion slot, and a plurality of pin attachment holes disposed between the insertion slot and the grooves. Contact pins are approximately L-shaped and pivotally held in the pin attachment holes, respectively, in the vicinity of central bent portions of the contact pins. When the connector housing is attached to a base board and the companion board is inserted in the insertion slot, ends of the contact pins are connected to a circuit pattern on the base board and opposite ends of the contact pins are connected to a circuit pattern on the companion board. The base and companion boards are therefore electrically connected to each other substantially perpendicularly to each other.

Abstract: A printer head having a circular first yoke, a cylindrical permanent magnet fixed on the circular first yoke, a (n) number of electromagnets (n is an integer) positioned on a circle on the first yoke within the permanent magnet having predetermined angle intervals, a ring shaped second yoke fixed on the permanent magnet so that the upper surface of the second yoke is on the same plane as that of the upper surface of the electromagnets, a ring shaped spacer positioned on the second yoke, a disk shaped spring fixed on the spacer having a common outer ring and a (n) number of projections projected in the internal direction from the common outer ring, (n) number of armatures each fixed on each projection of the spring, (n) number of print needles each fixed to each armature so that a print needle is perpendicular to the plane of the spring, a circular yoke plate fixed on the spring having (n) number of radial slits for accepting the armatures and the width of each slit being narrower than the width of projection

Abstract: A serial printer head is provided which comprises a sandwich structure (1,3,5) of a first circular yoke plate (1), a cylindrical magnet (3) and a ring shaped second yoke plate (5); a plurality of electromagnets (2,4) positioned on the first yoke plate (1) at predetermined angle intervals; an armature-print-needle assembly (7,8,9,10) having a circular resilient spring (7), a plurality of armatures (8) and a plurality of print needles (9) placed on the sandwich structure (1,3,5) so that the sandwich structure (1,3,5), electromagnets (2,4) and the armatures (8) provide first a substantially closed magnetic path; and an adjusting yoke (12) attached to the sandwich structure (1,3,5). The adjusting yoke (12) has the magnetic characteristics that the magnetic reluctance increases as the temperature increases. Although the flux generated by the permanent magnet (3) is changed due to the change of the temperature, that flux change is compensated for by the presence of the adjusting yoke (12).

Abstract: A printer head for mosaic printing having a plurality of needles positioned on a straight line each being selectively driven towards a paper through an ink ribbon has been found. The printer head comprises of a cylindrical permanent magnet, a first yoke covering the bottom of the permanent magnet, a plurality of electromagnets each positioned on a circle on the first yoke with the predetermined angle intervals, a disk shaped spring having an outer ring and a plurality of projections towards the center of the disk, a plurality of armatures each attached to the related projection of the disk spring, a plurality of print needles each attached to the related projection of the disk spring so that each of the needles has the perpendicular component to the disk spring plane.