Printhead and blades therefor

A printhead comprising a plurality of the printing blades, each of said printing blades comprising a flat generally annular rim, a flat-spiral substantially planar coil retained in said rim and energizable for interaction with a magnetic field to effect movement of the rim in a predetermined direction parallel to the plane of the coil, a mounting portion spaced from the rim and substantially parallel to the plane of the coil, and a pair of resilient mounting arms spaced apart in the predetermined direction and extending from the mounting portion to opposed points on the rim, an elongated arcuate printing arm extending from the rim generally in the predetermined direction and terminating in a printing tip,

• an elongated stabilizing member extending from the concave side of said printing arm intermediate the ends thereof substantially parallel to the plane of the coil
• means for arranging said printing blades in a stack with the planes of said coils parallel and with said printing tips of said blades being aligned in a direction substantially normal to said planes,
• insulating means for insulating said blades from one another in areas having a difference in electrical potential,
• means for retaining said blades in said stack,
• said printing arms of adjacent ones of said blades being oppositely curved and arranged with the concave sides thereof facing each other to provide a wide separation area therebetween in directions parallel to said planes,
• said stabilizing members of adjacent ones of said printing arms overlapping and being aligned in a direction substantially normal to said planes for cooperation to divide the separation areas between said arms into outer regions adjacent to said printing tips and inner regions adjacent to said rims,
• said separation areas being sufficiently large to prevent wicking of ink along adjacent printing arms from the printing tips thereof to said rims, the outer regions of said separation areas serving to collect particulate debris and isolate it from the inner regions thereby to prevent interference with the anti-wicking function of the inner regions.

A flat printing blade comprising a flat annular frame of electrically conductive material, said frame comprising a rim portion, said rim portion comprising a forward section and a rear section, a flat, spiral, substantially planar coil retained in said rim portion, said coil being double sided with a thin electrically insulating substrate separating the sides thereof, each side of said coil comprising a series of turns, one end of the turns of each side of said coil being electrically connected to a respective one of said front end rear sections, the other end of the turns of each side of said coil being connected together,

• means for electrically isolating said rear and forward sections from one another, said frame comprising a mounting portion spaced from the rim portion and substantially parallel to the plane of said coil, said mounting portion comprising a forward section and a rear section, said frame comprising a pair of resilient arms spaced apart in the predetermined direction with each arm extending from a respective mounting portion section to opposed points on the rim,
• means for energizing said coil for interaction with a magnetic field to effect movement of the rim portion in a predetermined direction parallel to the plane of the coil comprising,
• means for energizing said coil through a respective one of said sections of said mounting portion of said frame, an associated one of said arms and a respective one of said sections of said rim portions of said frame, and through a respective other one of said sections of said mounting portion of said frame, an associated other one of said arms and the other of said sections of said rim portion,
• an elongated arcuate printing arm extending from the rim generally in the predetermined direction and terminating in a printing tip, and an elongated stabilizing member extending from the concave side of said printing arm intermediate the ends thereof substantially parallel to the plane of the coil.