A high speed magnetic printer

The potential virtues of magnetic printers have long been appreciated [1]. They include quiet, non-impact operation, high speed, the use of plain paper, and minimal sensitivity to humidity conditions. We report on a magnetic printer that has been extensively tested and shown to demonstrate these advantages. The tests have concentrated on the system's performance as a high speed printer of alphanumeric characters selected by a coded digital input. However, the system can also function as a plotter of any figure that can be composed from arrays of dots. The principal features are the following: Any format of alphanumeric characters may be printed at an appropriate line density. The rows of characters may be up to 14 inches long. Paper speed is normally 16.7 inches/sec. Thus, at the common density of 6 lines/inch, the printer operates at 6000 lines/minute. The stationary printing heads can produce a 14 inch long row of dots across the width of the paper. Dot density is 120 dots/inch in this transverse direction. In the longitudinal direction of paper travel, the dot density is generally maintained at 96 dots/inch. The 1672 printing locations on the magnetic recording head are selected by a coincidnt current scheme that utilizes novel integrated drive circuitry. The head "writes" the characters as magnetic latent images composed of dots on a 16 inch wide continuous loop of magnetic tape. The magnetic image is "developed" by exposing the tape to a dry magnetic ink which is attracted to the written dots. The ink images are transferred to paper and sealed by heated rollers.