Abstract: A cap actuation mechanism for placing a cap, movably mounted on a cap carriage of an ink jet printer maintenance station, into sealing engagement with the nozzle face of the printhead of the printer. The cap mechanism functioning in response to movement by the cap carriage which in turn is moved by printer's print cartridge carriage when it leaves a printing zone for servicing by the maintenance station.

Abstract: According to the present invention, a plurality of cores with electromagnetic coils wound thereon are arranged annularly on one side of a polygonal plate-like yoke; a plurality of armatures with needles connected thereto are opposed to end faces of the cores; there is provided a polygonal, side magnetic path plate which has side magnetic paths each positioned between adjacent such armatures and which holds the armatures so as to permit the armatures to rise and fall; support rod portions coupled magnetically to the corners of the side magnetic path plate are formed on the yoke; and magnetic flux is passed through the support rod portions and the corners of the side magnetic path plate.

Abstract: A dot printer head including a plurality of cores each surrounded by a coil, a yoke connected to the cores magnetically, and a plurality of armatures each facing one of the cores and the yoke and having one end to which a needle is connected. A plurality of projections are provided on the yoke, and each armature has an opening in which one of those projections is engaged. This arrangement enables each armature and the yoke to face each other in a large area, while the area in which they face each other and which extends in parallel to the armature can be small. The pivot about which each armature is rotatable can be brought closer to the corresponding core. This enables a reduction in the air gap between the armature and the core and thereby the production of a large attracting force from a small magnetomotive force. It also enables a reduction in the equivalent mass of each armature and thereby an increase in the speed of printing and a reduction in the power consumption of the printing apparatus.

Abstract: The invention provides a process for producing a dot printer head wherein a plurality of needles having their ends arranged along a straight line have gradually increasing lengths towards opposite outer end ones thereof so that when the needles are being inserted into respective needle holes in a needle guide, they can be positioned one after another each under the guidance of a needle located outwardly adjacent thereto. Thus, even where an arrangement of needles is such that there remain some gaps between adjacent needles, the needles can be guided one after another beginning with the outermost ones thereof and be inserted smoothly into the needle holes.

Abstract: The printhead is constructed such that opposed surfaces of armatures are formed between the armatures adjacent to each other with small gap being left therebetween and cores opposed to each of the armatures are provided with alternative opposed magnetic fluxes. The armatures are supported in such a way that the guide holes formed in the middle of each armature are engaged with the fixed armature guides without interfering with their side surfaces, and thereby side magnetic paths of sufficient cross sectional area can be formed, and further their equivalent mass can be decreased and a high speed printing is enabled, and the armatures can be moved smoothly.

Abstract: A dot printer head in which a radial array of armatures are disposed opposite to a yoke and cores equipped with coils, and the armatures are actuated together with needles by exciting the coils to perform a desired printing operation. In this arrangement, a magnetic flux generated from each core flows to the yoke via the associated armature and then returns to the former core while partially flowing through another magnetic path by way of the adjacent armature to the yoke and returning to the former core, whereby required magnetic paths are obtained without the necessity of increasing the areas of the mutually opposed surfaces of the armature and the yoke. Thus, the radial width of the yoke is reduced as well as the distance from the fulcrum of the armature to the core, so that the distance from the fulcrum of the armature to the fore end thereof can be sufficiently lengthened against the distance from the armature fulcrum to the core.

Abstract: A dot printer head in which a plurality of needles are so arrayed that tips thereof are aligned linearly and are driven by electromagnets disposed in an annular arrangement. In this structure, the needles are guided by means of an intermediate guide plate and a tip guide plate in such a manner that the linear alignment of the needle tips is maintained regardless of any inclination of the needles, whereby the length of each needle is shortened and the amount of flexure thereof is reduced to enable fast printing as well as to enhance the durability.

Abstract: In printing head of a dot printer according to this invention, a groove having width a little greater than diameter of top end of a needle is formed in front of a needle guide to guide the needle, position of top end of the needle is specified between the bottom of the groove and front surface of the needle guide, when the needle pushes through the printing head it returns rapidly, when top end of the needle is deformed it does not stick to the needle guide, a gauge spacer is interposed between the yoke and the guide holder to be assembled thereby position of top end of the needle is specified, and plural sheets of other spacer are overlaid and removed separately during grinding top end of the needle thereby the needle without deformation at top end can be formed and used for a long time.