Abstract: A method and apparatus for controlling the volume of ink droplets ejected from thermal ink jet printheads is disclosed. The electrical signals applied to heating elements for generating droplet ejecting bubbles thereon are composed of packets of electrical pulses. Each pulse and spacing therebetween are varied in accordance with one or more whole, clock or timing units. The number of pulses per packet and width of pulses and spacing therebetween are controlled in accordance with the manufacturing tolerance variations, the location of the addressed heating element in the printhead, the number of parallel heating elements concurrently energized, and optionally the temperature of the printhead in the vicinity of the heating elements to maintain the desired volume of the ejected droplets.

Abstract: An improved ink jet printhead comprising upper and lower substrates that are mated and bonded together with a thick film insulative layer sandwiched therebetween. One surface of the upper substrate has etched therein one or more grooves and a recess which when mated with the lower substrate will serve as capillary filled ink channels and ink supply manifold, respectively. The grooves are open at one end and closed at the other. The open ends serve as nozzles. The manifold recess is adjacent the grooved closed ends. Each channel has a heating element located upstream of the nozzle. The heating elements are selectively addressable by input signals representing digitized data signals to produce ink vapor bubbles. The growth and collapse of the bubbles expel ink droplets from the nozzles and propel them to a recording medium.

Abstract: A thermal ink jet printer has an ink delivery system which enables rapid changes and increased operational speeds when changing between full color, highlight color and monochrome mode of operation. In response to selection of a desired mode, ink supply systems associated with particular cartridges are selectively purged and interconnected to ink supply systems of the colored inks which will be used in the selected operational modes.

Abstract: An externally stimulated continuous stream ink jet printer which suppresses or controls the formation of satellite droplets so that they are not charged differently from the main droplets. Thus, when the two are merged, indeterminate charges are not produced which would impact the print quality of the printer. The satellites are suppressed by impressing on the printer ink streams a combination of time-varying pressures. In one embodiment, the time-varying pressures are generated by two time-varying voltages applied to the EHD electrodes. One pressure has a fundamental frequency with the second pressure having a second harmonic frequency, these two pressures having a predetermined phase and amplitudes with respect to each other. The fundamental frequency is selected for a required drop spacing to stream diameter ratio.

Abstract: An electrohydrodynamic stimulated ink jet printing device and method of manufacture which eliminates the prior art problem of ink wetting the dielectric spacer between the stimulating electrode and the ink jet nozzles. The nozzles are electroformed on one side of a sheet of dielectric material and the EHD electrodes are electroformed on the other side of the dielectric material in registration with the nozzles. The dielectric material is removed from the nozzles by using the nozzles or the electrodes as masks. The internal surface of the dielectric material is coated with a one of a number of coatings non-wettable by the ink such as a mixture of paraffin and ethylene vinyl acetate copolymer dissolved in a light aliphatic hydrocarbon, such as VMP naphtha.

Abstract: A plurality of disposable, individually replaceable ink supply cartridges are mountable on the carriage of an ink jet printer. Each cartridge has a thermal printhead fixedly attached thereto. A constant slightly negative pressure is maintained at the nozzles of the printhead by means of a secondary reservoir with a level of ink maintained below the ink supply. The majority of the ink is stored in a hermetically sealed main reservoir in the cartridge which contains the ink supply at the negative pressure. A passageway provides ink from the main reservoir to the printhead nozzles. The secondary reservoir holds an air pocket at atmospheric pressure and releases air into the main reservoir as required to maintain the desired negative pressure constant therein as the ink supply is depleted. The passageway entrance is sized to maintain a meniscus when the cartridge is tilted to prevent loss of the desired nozzle pressure by air from the second reservoir.

Abstract: A magnetic brush apparatus which minimizes the escape of toner and/or carrier particles by means of a magnetic field shaping device which minimizes the presence of magnetic lines of force projecting axially outward from the magnetic brush rollers. Examples of magnetic field shaping devices are a piece of ferro-magnetic material and a magnetic field shaping magnet.

Abstract: A magnetic brush cleaning apparatus which includes a magnetic brush roll having a plurality of magnets mounted therein, a reservoir for carrier particles closely spaced from the magnetic brush roll, a pickoff for removing a part of the carrier particles constituting the magnetic brush during the rotation of the magnetic brush roll, and an exit at the lower end of the reservoir for directing the carrier particles onto the magnetic roll, so that the reservoir, the pickoff, the exit and the magnets cooperate to cause the circulation of carrier particles between the magnetic brush roll and the reservoir whereby a portion of the magnetic brush is continuously removed and reformed during the rotation of the magnetic brush roll. In another embodiment, the reservoir, the pickoff and the exit are used only during servicing of the cleaning device.

Abstract: An electrostatographic development and cleaning system employing conductive carrier particles. The carrier particles comprise a core having magnetic or magnetically-attractable properties which is coated with a polymer to provide particles having a resistivity of less than about 10.sup.10 ohm-cm. The carrier particles also provide efficient removal of residual toner deposits from a photoreceptor surface after a copying operation.

Abstract: A magnetic support member, and apparatuses including the support member for magnetic cleaning or magnetic development in an electrostatographic reproducing machine. The magnetic support member is formed of a composite composed of elongated bodies of a magnetic material having a high magnetic permeability in a non-magnetic matrix. The magnetic support member includes a support surface and the elongated bodies are aligned with respect thereto such that the direction of their long dimension is generally perpendicular within about .+-. 30.degree. to the support surface or to a tangent to the support surface.

Abstract: A cleaning apparatus for use in an electrostatographic reproducing machine and an electrostatographic reproducing machine utilize magnetic attraction to aid in removing magnetic toner from an imaging surface or cleaning device. The cleaning apparatus comprises a prolate magnet having at least one pole adjacent the surface to be cleaned so that a gap of from about 0.005 to about 0.050 inches is defined. The ratio of the longitudinal width of the magnetic pole to the gap between the magnetic pole and the surface to be cleaned is maintained within the range of from about 0.5 to about 2.