Electromagnetic head with separate addressability resolution and imaging

Abstract

An electromagnetic printhead is fabricated with a common flux returning backplate and an array of writing elements extending from the common backplate. The writing elements consist of large pedestals and small pedestals. The placement of the large pedestals provides addressability resolution; the small pedestals provide imaging resolution. The large pedestals accept electromagnetic flux from addressing conductors and transfer the flux through the respectively related small pedestals to an image receptor. There are several fabrication techniques which are eased by the separation of addressability resolution and imaging resolution, primarily because the wide separation of the large pedestals required for the addressing conductors mandate relatively massive removal of material and thus suggest relatively low precision machining techniques. The imaging resolution requires both high spacial precision and accurate dimension control, normally achievable by relatively high precision techniques. With the functions addressability resolution and imaging resolution functions separately provided, the best and most economical techniques may be used for each. The magnetic flux path for recording may be either vertical or in-plane, and the flux return may be common via the relatively low reluctance path provided by very large area paths through the mass of nonferromagnetic material to the common flux returning backplate. This simplified printhead lends itself to the use of standard flexible circuit fabrication techniques for the addressing conductors.