Abstract: A printer employing a scanning electrostatic print head includes a sensor to determine dimensional variations in a printable dielectric material, such as paper, on which a latent electrostatic image is disposed. A charge deposition delay circuit is in electrical communication with the scanning print head which allows properly positioning the electrostatic image on the dielectric material to compensate for the dimensional variations.

Abstract: A continuous purification method for removing neutral, as well as ionic, contaminants from liquid toner in an electrostatic printing system is disclosed. This method involves circulating liquid toner from a toner supply tank through a common volume which includes the toning applicator. The liquid toner is introduced to solid and ionic contaminants in the common volume and as the toner is circulated back to the toner supply tank for each toning pass, some contaminants and toner are left in the common volume. Next a wash fluid from a wash fluid supply tank is circulated through the common volume after each toning pass, the wash fluid mixing with the toner and the contaminants. This mixture is then passed through an electrophoretic purifier to remove the contaminants. Then the mixture passes through a porous particulate filter to remove any remaining contaminants before it returns back to the wash fluid supply tank.

Abstract: A power module including an RC circuit is uniquely associated with each of a plurality of electrodes of an electrostatic print head to individually control the rate of charge decay of a voltage disposed thereon. The resistor of the RC circuit is a potentiometer that may be manually adjusted to obtain an optimal decay rate. A paper supply roller and take-up roller accurately position dielectric material, such as a paper web, adjacent to the electrodes of the print head, which is located between the rollers. The electrodes are typically a plurality of wires. The print head moves across the width of paper web to dispose thereon a plurality of charge areas corresponding to a strip of a latent image. Control circuitry synchronizes the movement of the print head and the web to produce a plurality of abutting strips of charge areas, producing a complete latent image.

Abstract: A dual separator purification system and method for removing particulate as well as ionic contaminants from liquids is disclosed. The present invention is particularly useful in the electrostatic printing industry. The system comprises two disparate separators connected in series. The first separator has a repelling electrode and a rotating drum which collects charged particulate contaminants and debris. A liquid such as spent liquid toner is passed through a gap between the repelling electrode and the rotating drum. The contaminants, including colored toner particles and paper debris, move electrophoretically through the gap and adhere to the rotating drum. Upward motion of the drum surface brings the accumulated deposit out of the gap region and to a scraper blade which removes the deposit from the drum for subsequent disposal. The partially purified liquid is collected and then passed through a second separator which has a spirally-wound laminate of porous and electrically conductive layers.

Abstract: A toning method for electrostatic printers and copiers where paper is wound on a supply roll and moved toward a takeup roll. After a latent image of a first color is written and the image area is wound toward a takeup roll, toner of a first color is applied while rewinding the image bearing web toward the supply roll. After the image area passes the writing head, the web is stopped and reversed so that a latent image corresponding to a second color may be written. Once the image region passes toning stations, the web is stopped and again reversed. During reverse direction travel of the image region, toner of a second color is applied and the image region is again wound on the supply roll. The process continues for toning all colors during the rewind operation. Although the image area may move at variable speeds during image writing, the image area is moved at constant speed in the reverse direction for toning.

Abstract: An electrostatic drum printer having a linear array of charging elements scanning a sheet of paper with a helical stripe pattern. The head is supported on a lead screw which advances the head as the drum rotates. The head writes an electrostatic latent image of digital words which visually appear as adjacent columns once the sheet is toned and laid flat. A toning shoe assembly is carried along with the head, with a single toning shoe, having a toner of a specified color, adjacent the head. When the head reaches the end of a scan, the head and shoe assembly is retracted for fly back to a starting position. A new toning shoe, having a toner of another color, may be indexed into position near the head. The retracted elements are pushed forward for starting another scan. With several scans, a color image may be recreated.

Abstract: A recording head for use in an electrostatic printer comprises four staggered rows of styli. Signals for driving each row of styli are transmitted through a buffer wherein the signals for the first row of styli are transmitted without delay to the styli, the signals for the second row of styli are transmitted with an appropriate delay of a first selected time, the signals for the third row of styli are transmitted with an appropriate delay of a second selected time and the signals for the fourth row of styli are transmitted with an appropriate delay of a third selected time. The delay means comprises a random access memory driven by address counters controlled by a control sequencer to function as a delay. The four staggered rows of styli are formed by a novel method wherein the styli in the second row are formed between the styli in the first row and the stylis in the third and fourth rows are formed by making use of the grooves formed between the styli in the first and second rows.

Abstract: A recording head for use in an electrostatic printer comprises four staggered rows of styli formed by a novel method wherein the styli in the second row are formed between the styli in the first row and the styli in the third and fourth rows are formed by making use of the grooves formed between the styli in the first and second rows. By forming the rows of styli on a cylindrical drum, two recording heads are obtained from each fabrication run wherein the recording head in one set of styli is the mirror image of the recording head in the other set of styli. Should an error occur in the manufacture of the styli by placing the third row of styli in the grooves where the fourth row of styli normally belongs, the resulting recording heads are identical to those obtained with the proper placement of the third and fourth rows with the exception that the position on the drum of each type of recording head is reversed.