Patents Examined by George H. Miller, Sr.
  • Patent number: 5128697
    Abstract: An improved electrographic writing head employs interleaved arrays of writing nibs and small geometry, high impedance, thick film resistors and semiconductor driver circuits fabricated on a glass epoxy substrate. The writing head achieves significant savings in manufacturing costs by using low cost printed circuit and thick film technology. Power consumption may be reduced by more than half over prior art devices due to the high impedance of each thick film pull up resistor coupled with a associated writing nib. A ground plane is disposed internally of the substrate and between adjacent arrays of writing nibs. The ground plane prevents electrical interaction between the substrates and prevents the formation of parasitic nib-to-nib capacitance by shunting parasitic capacitance currents to ground. The ground plane thus reduces the possibility of flaring and substantially eliminates inadvertent writing by adjacent nibs.
    Type: Grant
    Filed: November 28, 1990
    Date of Patent: July 7, 1992
    Assignee: Rastergraphics, Inc.
    Inventors: Andreas Bibl, George H. Fellingham