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 neb. 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.

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.

Abstract: An improved toner applying apparatus is provided for developing an electrographic latent image formed on the charge retaining surface of a moving recording medium. The toner applicator includes a housing defining an internal reservoir and including a series of longitudinal, parallel toner applying recesses which are disposed for developmental engagement with a moving recording medium across its entire width. Each toner applying recess communicates with the reservoir. Internal baffles are provided across a toner inlet to the reservoir chamber to provide uniform fluid pressure throughout the reservoir. The parallel toner applying recesses provide a more even and constant flow of toner than is possible in prior art roller applicators and completely eliminate the problem of electrodeposition or plating up of toner particles on the applicator.

Abstract: An electric field paper stabilizing system for an electrographic plotter, printer, or the like includes a continuous transport belt for passing a recording medium in substantially a complete revolution past a writing head. The belt is conductive or has a conductive surface conformably coated with a minimally thin dielectric material of high dielectric strength and permittivity. A recording medium such as electrostatic writing paper has a conductive surface adjacent the dielectric coating on the conductive transport belt. Electrode means are provided in the dielectric coating for holding the paper at ground potential. A differential potential is applied between the back side of the paper and the conductive transport belt whereby the paper and belt function as parallel conductive plates of a capacitor. The electric field developed between the conductive paper and the belt provides a strong hold down force which immovably registers the paper to the belt.

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 separate glass epoxy substrates disposed in adjacent back to back relation. 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 an associated writing nib. A ground plane is disposed between the adjacent substrates 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.

Abstract: A device for providing extremely accurate tracking and control of a continuous belt or web driven by at least one roller such as a paper transport belt for an electrostatic plotter, printer or the like includes a method for cancelling out the effect of belt edge irregularities by sampling the irregularities in the edge of a belt at precise positional intervals for an initial rotation of the belt and storing the sampled values as elements in a reference array. The reference array is corrected to include an error component representative of linearly increasing measurement of error for each of said array elements due to lateral shifting of the belt. During subsequent operation, the lateral displacement of the belt is continuously scanned for each of said positional intervals with respect to a corresponding element of the array.

Abstract: A vacuum transport belt for use in a multipass, multicolor raster printer has a vacuum attach means for providing a strong hold down vacuum force in the direction of paper travel for complete registration of a recording material with respect to a writing head and toner system. The vacuum attach means comprises a thin metal strip bonded to a transport belt such that the surface of the strip is substantially flush with the surface of the belt. A strong hold down vacuum is conducted through channels underneath the bonded strip to a series of closely clustered apertures which form a vacuum contact region on the strip. The force of the vacuum applied at the contact region and the substantially flush contact between the surface of the strip and the transport belt tightly seals the entire surface of the recording material to the transport belt, thereby registering the recording material precisely to the transport belt in an invariant desired alignment with a writing head and toner system.

Abstract: A multipass, multicolor electrostatic plotter or printer has a continuous vacuum transport belt rotatable for substantially a complete revolution past a stationary writing head. The vacuum transport belt provides a vacuum to the entire contacting surface of a recording medium to stabilize and register the recording medium with a previously unattainable degree of invariance, thereby enabling information to be printed upon the recording medium simply by moving the transport belt with respect to a stationary electrostatic writing head disposed for contacting the recording medium across its entire width.

Abstract: A vacuum transport belt for use in a multipass, multicolor raster printer has a vacuum attach means for providing a strong hold down vacuum force in the direction of paper travel for complete registration of a recording material with respect to a writing head and toner system. The vacuum attach means comprises a thin metal strip bonded to a transport belt such that the surface of the strip is substantially flush with the surface of the belt. A strong hold down vacuum is conducted through channels underneath the bonded strip to a series of closely clustered apertures which form a vacuum contact region on the strip. The force of the vacuum applied at the contact region and the substantially flush contact between the surface of the strip and the transport belt tightly seals the entire surface of the recording material to the transport belt, thereby registering the recording material precisely to the transport belt in an invariant desired alignment with a writing head and toner system.