Abstract: A printing machine in which magnetically permeable marking particles develop a latent image recorded on a photoconductive member. A read head is positioned on the opposite of the photoconductive member to detect magnetic field intensity effects produced by the leading edge and the trailing edge of the marking particles on the characters recorded. The detected signals are used to control the magnetic quality of the developed image.

Abstract: A magnetic ink monitoring system is provided including a reader which outputs an electrical signal representative of a magnetic flux, a storage mechanism which stores an integral representation of a signal from a standard magnetic ink display, and a comparator operatively connected to the read means and the storage means to compare an integral signal of the electrical signal of the magnetic ink display to the integral representation of a signal from a standard magnetic ink character.

Abstract: A fraud prevention system for magnetic ink character recognition includes providing a colored, highly reflective media and magnetic media over a non-magnetic toned image which can be an on-line or off-line component of an imaging apparatus. Colored media and magnetic ink are applied to selected characters from a thin film that includes a layer of colored media and a layer of magnetic media by utilizing a heater member to promote release of the colored and magnetic media to the previously toned characters.

Abstract: An aperture plate for an ink jet printer of the continuous stream type is made corrosion resistant to the ink for long printer operating times. The aperture plate is made corrosion resistant by ion implantation, preferably of chromium ions by an ion beam implanting device. The walls of the aperture plate nozzles are substantially uniformly implanted by rotating and concurrently angling the aperture plate relative to the ion beam direction. The ion beam density and ion potential are regulated to predetermined ranges to assure effective corrosion protection while preventing overheating which will warp or embrittle the aperture plate.