Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Addressable Magnetic Printing Drum

IP.com Disclosure Number: IPCOM000083640D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 37K

Publishing Venue

IBM

Related People

Lo, DC: AUTHOR [+2]

Abstract

The ink used on a magnetic printing drum comprises a magnetic material in amorphous form soaked in an oil base with high-surface tension. The ink, once magnetized, requires a time t(o) greater than say 10/-6/ seconds to relax (for a granule of diameter A approx. = to 100 mil).

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Addressable Magnetic Printing Drum

The ink used on a magnetic printing drum comprises a magnetic material in amorphous form soaked in an oil base with high-surface tension. The ink, once magnetized, requires a time t(o) greater than say 10/-6/ seconds to relax (for a granule of diameter A approx. = to 100 mil).

The ink is forced through a nozzle coupled with a pressure oscillator such that the ink is granulated with a typical diameter A, and mixed with a supporting hydrophobic liquid which has very similar density, and also with high-surface tension. In this mixture, the ink is preserved in spherical form and retains its individual granulation.

The drum matrix comprises a thin drum surface coated with permanent magnetic material in arrays of circular dots, arranged in a pattern which corresponds to that of a basic matrix display. The dotted drum surface is sealed with a thin layer of hydrophobic (with respect to both the ink oil and the supporting liquid) material.

Each matrix spot can attract one ink granule by the magnetic field of the spot; however, if more than one granule is attracted to the same spot, the centrifugal force of the rotating drum forces the extraneous droplet to fly away. A magnetized belt bending over a co-rotating cylinder results in the same effect. The diameter of the magnetized dot is smaller than the ink granule, for example, it may equal A/2.

The drum surface 2 passes over an ink or an ink mist reservoir 4 at a point where a strong field is superimposed with the basic matrix field. This pickup field can be generated by a stationary permanent magnet 6 or a pulsating field synchronized with the passage of the matrix spots. The strong pickup field assures that ink is attached to the drum surface; it also remagnetizes the matrix spots. Extraneous ink is spun away by the centrifugal force.

For writing on an advancing paper 8, a strong pulse with polarity opposite to that of the matrix spot, and with pulse width t shorter than t(...