Integrated microchannel print head for electrographic printer

Electrographic printing apparatus for forming a toner image on a recording medium, comprising:

• a) a magnetic brush having a rotatable magnetic core and a stationary outer shell;
• b) a developer supply for supplying a magnetic developer powder to the magnetic brush;
• c) a print head on the outer shell, the print head including,
• i) an array of microchannels in a substrate for forming a plurality of parallel lines of developer in the channels,
• ii) a corresponding plurality of transfer electrodes located in the microchannels for selectively transferring developer from the lines to a receiver,
• iii) driver circuitry located on the opposite side of the substrate from the microchannels for generating and applying transfer signals to the transfer electrodes,
• iv) a power supply connection for applying power to the drive circuitry,
• v) a print signal input connection for applying print signals to the print head, the print signal input including a number of electrical conductors fewer than the number of transfer electrodes,
• vi) logic and control means located on the opposite side of the substrate from the microchannels for applying the print signals to the drive circuitry, and
• vii) electrical connection between the driver circuitry and the transfer electrodes being formed by via plugs from the bottoms of the microchannels to the opposite side of the substrate;
• and
• d) a receiver electrode arranged in spaced relation to the array of microchannels to define a recording region through which the receiver can be moved.