Abstract: A low inertia rotary drum transport for flexible sheets, the drum rotating at a relatively low speed for loading a sheet, rapidly accelerating to a relatively high speed for processing the sheet, then rapidly decelerating to the relatively low speed for unloading the sheet. A gate and conveyor are controlled to supply the sheet to the drum in precise registration. Vacuum apparatus and a charge corona are provided for attaching the sheet to the drum, the vacuum attaching the leading portion of the sheet, the corona charging the middle portion of the sheet to hold the sheet to the drum by electrostatic attraction, and the vacuum attaching the trailing portion of the sheet. Air pressure apparatus detaches the leading portion of the sheet for unloading.

Abstract: Fouling of an electrostatic ink jet head is sensed and causes shutoff of the head and of the associated electronics. The fouling is sensed by detecting contamination of the charge electrodes or of the deflection plates by conductive ink, the detection being by sensitive circuitry employing diodes.

Abstract: A high pressure fluid source is connected to a primary orifice and a valved orifice of a binarily activated pressure regulator. The primary orifice alone supplies the fluid at a pressure below the minimum desired, and both orifices together supply the fluid at a pressure greater than the maximum desired. A sensor at the output is adjusted to open the binary valve when the minimum pressure is reached, and close the valve when the maximum pressure is reached, thus cycling between the two conditions.

Abstract: Ink jet print spot intensity is modulated by controlling the volume of ink per print spot to compensate for various paper, environmental and ink characteristics, and thereby attain uniform print quality.

Abstract: An ink jet printer which includes data storage and which prints with multiple jets in an interlace fashion on paper supported on a rotating drum is provided with a bidirectional ink jet transport for moving axially along the drum. A gating arrangement is provided for gating the stored data to printing controls for the multiple jets in a first order upon the transport moving in a first axial direction and for gating the stored data to the printing controls in a second order upon the transport moving in the opposite axial direction.

Abstract: A sensing arrangement for accurately detecting the position of ink jet or similar drop impact thereon. The drop impact occurs on the surface of a poled piezoelectric between two parallel conductors. The charge generated by drop impact is localized, the degree inversely dependent upon the piezoelectric thickness, so that the signal generated in a conductor is dependent upon the distance of the impact location from the conductor. Thus, using transimpedance amplifiers, the difference of the output signals indicates the impact position.

Abstract: A pressurized fluid issuing from a nozzle orifice to form a jet stream is perturbated by a hybrid velocity and pressure modulation to form a stream of drops. A perturbation means, such as a piezoelectric crystal, is mounted both to vibrate the nozzle for modulating the stream velocity and to perturbate the interior volume of a fluid cavity communicating with the nozzle for also modulating the pressure of the fluid.

Abstract: A method and apparatus for reducing the effects of electrostatic charge repulsion and aerodynamic drag on a stream of ink drops in an ink jet printer. This reduction is accomplished by the non-sequential printing of the ink drops as they issue from the nozzle, i.e., drops issuing sequentially from the nozzle are never printed adjacent to one another. This maximizes the inflight distance between successive ink drops, reducing drop interaction. The slight misalignment in the printing which results from the non-sequential printing may be corrected by either displacing the deflection plates a sufficient angle with respect to the print line or by a corrective signal added to the signal input so that the desired slant results with the non-sequential printing.

Abstract: In a copier, an original document feed moves two originals to be copied simultaneously onto a document glass. The document glass is 11 inches by 17 inches and accommodates two 81/2 by 11 inch documents side-by-side. The dual document feed is loaded sequentially with two originals and registers the two originals side-by-side to right and left corner references at an entry station. The entry station includes aligning rollers whereby the operator need only position the originals close to the correct position. The aligning rollers then corner-register the documents side-by-side. After the originals have been registered side-by-side in the entry station, they are automatically fed forward substantially simultaneously to be registered side-by-side on the document glass. Electronic control circuits are shown whereby the dual document feed apparatus may be controlled to feed either single or dual original documents.

Abstract: Ink supply system and sequencing for purge, startup, operation, and shutoff of pressurized ink jet systems. Employing an ink jet head having an inlet, startup is accomplished by filling the head with ink, closing an inlet valve, building pressure behind the valve to a level significantly greater than required for operation, and opening the valve. The system includes an inlet valve connecting a pump from a reservoir to the ink jet head, and an outlet valve connecting an outlet from the head to the reservoir and a vacuum source. At shutoff, the inlet valve is closed with the outlet valve open to create a negative pressure in the head.

Abstract: A corona and associated electrical drive as shown herein, neutralize the static charges on non-conductive sheets or webs. The neutralization of static charge is accomplished by passing the material to be neutralized under a double wire corona. Both wires in the corona are connected to an AC signal. The AC signal drives both wires with a signal that alternates in polarity at frequency f. The wires are spaced apart a predetermined distance calculated from a function dependent upon the frequency of the AC signal and the speed of the paper moving under the corona wires. The predetermined distance is such that a given area of the paper will pass under one wire at a first polarity and under the second wire at the opposite polarity. Further enhancement of neutralization can be accomplished by using a second double wire corona out of phase with the first double wire corona.

Abstract: A system for fluid jet heads such as ink jet adapted for self-cleaning of certain clogs and purging of air from the head. The head includes a manifold communicating with at least one orifice to project a stream of fluid therefrom. Two fluid supply paths at different sides of the manifold supply pressurized fluid thereto. One of the supply paths is located at the top of the manifold and is reversible. If air or an impurity causing a nozzle clog is encountered in the head, the top path may be reversed so the fluid enters from one path and exits at the top. This establishes a crossing flow at the orifice, tending to loosen and remove the clog and purging the impurity or air from the head and out the reversible path.

Abstract: A dual antenna structure for inductive sensing of charged ink jet drops. The structure includes two sense rails or wires, each on an opposite side of a series of ink jet drop streams and perpendicular to the streams. Conductive shields are located on the fore and aft sides of each sense rail to shield the rail from all but a small portion of each drop stream path. A separate low impedance amplifier is connected to each sense rail and both are grounded in common to the shields. Using the sensor, various measurements may be made on a jet stream whose drops are charged, including jet alignment, drop arrival time for establishing velocity, charge electrode operation, and charge phasing.

Abstract: A charge electrode structure for electrostatic ink jet systems comprises a series of dielectric laminates having planar electrode laminates therebetween and openings therethrough for passage of the ink jet stream approximately normal to the plane of the electrodes. The electrodes for the same stream are electrically interconnected and energizeble to form a charging field similar to that of a tubular charge electrode parallel to the stream.

Abstract: Sub-harmonic charging and detection of charging phase synchronization in an ink jet system employing electrostatic deflection of individual ink jet droplets. The phase control employs filtration/narrow-band amplification at a sub-harmonic frequency from the normal drop repetition frequency, such that noise and extraneous drop rate machine signals are filtered. Sensing may best be accomplished by an inductive charge sensing element and detection of the filtered sensed signals by integration and by level detection.

Abstract: A nozzle array structure for pressurized fluid jets includes a uniform deposited membrane having an array of uniform small orifices therein overlaying a planar substrate having an array of larger aperture openings therethrough with approximately the same central axes as the orifice array. The method of making includes forming a substrate of a planar single crystal material oriented with the (100) planes parallel to the surface. A membrane comprising a uniform coating of an inorganic material is applied to the planar surface of the substrate. The substrate is preferentially etched from the rear surface to form an array of openings therein extending therethrough to the membrane. The membrane is then selectively eroded to form an array of uniform small orifices therein.

Abstract: Vacuum cleaned high voltage deflection electrode apparatus may be utilized in conjunction with further deflection electrode means to establish an electrostatic deflection field for ink jet. The high voltage electrode includes a pair of parallel planar fine screens interposed between two rows of ink jet stream paths and has a vacuum between the screens. Two separate rows of ink jet orifices may cause two rows of ink jet streams to be formed which pass through two corresponding rows of charging electrodes to selectively charge the drops upon breakoff. The drops pass on opposite sides of the high voltage electrode through the deflection field which deflects the charged drops and not the uncharged drop for selectively impacting a gutter or for recording. Significant ink mist may be generated and may come into proximity to the high voltage electrode which is then drawn through the screens by the vacuum to prevent mist accumulation on the electrode.

Abstract: A continuously operating transfer reproduction apparatus includes a cyclic control unit which automatically effects alternate redevelopment and reimaging cycles when reproducing multiple copies of the same master. An electrophotographic plate travels in a closed loop past a moving optical system which images the plate with a light image of the master creating a latent electrostatic image on the plate. The latent image is developed at a developing station and transferred to a substrate at a transfer station as the plate travels therepast. Increased throughput speed is achieved by effecting a fixed number of redevelopment cycles while the moving optical system is resetting. Thus, the plate continues its travel past the resetting optical system to the developing station where the latent image is redeveloped and thence to the transfer station for transfer of the developed image to a second substrate.