Abstract: The volume of ink ejected from an ink jet printing apparatus during one cycle of operation for printing a dot upon a recording medium is controlled within that cycle of operation by operating the ink jet apparatus via the application of a pulse train having a periodicity equivalent to the dominant resonant frequency of the ink jet apparatus. An electrical signal in the form of an earlier pulse train is followed by at least one additional electrical signal or pulse having a time delay and an ink jet transducer is selectively gated on or off by the electrical signals.

Abstract: A media transport mechanism including a high accuracy vacuum belt used in conjunction with a pinch roller assembly. The media transport mechanism includes a vacuum belt supportably wrapped around two sprocket assemblies and a plenum and disposed in facing relation to a print head. The vacuum belt has two pinch roller assemblies disposed in spaced-apart relation across the front surface of the vacuum belt, with each pinch roller assembly including two pinch rollers which, in conjunction with the vacuum belt, grip and advance a sheet of media across the front surface of the vacuum belt during printing. The plenum provides a vacuum hold-down force for holding the media flat against the front surface of the vacuum belt.

Abstract: A demand or impulse ink jet ejects droplets of hot melt ink. The hot melt ink is heated from a solid state to a liquid state in the jet prior to the ejection of droplets on demand. The ink is then cooled on striking the target. The ink may contain a wax.

Abstract: In a color printer including a print head for effecting printing with a phase change ink and provided with a reservoir for holding a supply of the ink, an ink replenishment assembly composed of an ink storage device for storing a plurality of pellets of the ink in solid phase, the storage device having an outlet and a channel for supplying the pellets to the outlet by the force of gravity; a pellet conveying device disposed between the storage device outlet and the print head and movable between a receiving position for receiving at least one pellet from the storage device outlet and a delivery position for conveying a pellet received in the receiving position to the print head reservoir; and a drive member coupled to the pellet conveying device for moving the pellet conveying device between the receiving and delivery positions.

Abstract: In an ink jet printer having a plurality of ink jet channels which are individually controllable to produce ink dots on a printing medium, crosstalk is reduced by activating each odd numbered channel in alternation with each even numbered channel, while offsetting the orifices of one group of channels from the other to compensate for the time difference between activations, and the voltage supplied to excite the channel transducers is varied as a function of the number of channels simultaneously exited to maintain a fixed excitation voltage across each transducer.

Abstract: A drive system for driving the transducers of an ink jet print head. A controller determines transducer activation periods during which one or more selected transducers are to be activated. During each transducer activation period a voltage source is activated. A drive circuit receives serial print data from the controller and couples the selected transducers to the voltage source. The voltage source can be provided with a waveshape circuit to produce a desired excitation waveshape.

Abstract: A sheet media feed mechanism including a sheet media tray, the sheet media tray having a lower tray for holding a stack of automatic-feed cut sheet media and an upper tray for holding individual sheets of manual-feed sheet media. The lower tray has a pair of corner-pick separators for separating the top sheet of sheet media from the stack. The upper tray has a frame positioned over a rear portion of the lower tray leaving a front portion of the lower tray exposed, and pair of flexible sidekicks extending out over the exposed portion and having a sheet media separator at the front tips of the sidekicks. A pair of D-rollers mounted on a shaft pick the top sheet of sheet media from the lower tray when no sheet media is present at the upper tray, the D-rollers also adapted to pick the top sheet of sheet media from the upper tray when at least one sheet of sheet media is present thereat. The picked sheet media is then fed to a feed path.

Abstract: An electro-expulsive device in the form of discrete units having a redundancy feature, minimal susceptibility to fatigue failure with a provision for transferring shock waves to and from abutting units.

Abstract: A printer having a printing mechanism for placing printed matter on a substrate, the printing mechanism including character printing elements and an electrically driven hammer unit which is connected to receive an actuating current and is operative for causing the printing elements to print characters on the substrate by impacting against the elements with an impact force dependent on the magnitude of the actuating current, the printer being further provided with: a substrate thickness monitoring device mounted in the printer for monitoring the thickness of a substrate disposed to be printed upon by the mechanism and for producing an electrical output signal indicative of the substrate thickness within a predetermined amount of time; and an actuating current control circuit connected to receive the output signal from the monitoring device and to control the actuating current in a manner to reduce the impact force when the substrate thickness is less than a selected value.

Abstract: A pixel row interlacing method and system, and print head for practicing same, for use with dot-matrix ink jet printers which apply ink to a substrate as elevated temperatures (e.g., phase change ink jet printers), which assures environmentally symmetric ordered placement of molten ink droplets and, thereby, achieves seamless dot-matrix printing and minimizes the horizontal striping or "banding" effects which are prevalent in prior art printers. Odd rows of print region are printed in one pass and the even rows of the same region are printed in the following pass. The guidelines for laying down dots are essentially: (1) adjacent dot rows should not be laid down in the same pass; (2) each dot row should be sandwiched by either (a) virgin paper on both sides of the dot row, or (b) ink on both sides of the dot row; (3) the first and the last dot row in each solid pattern are exempted from guidelines #2 and #3.

Abstract: A printer control system for controlling the transfer of image data to a printer marking engine, composed of: a main processing unit for controlling the operation of the system; an interface for receiving print data from an external device; a main bus connected between the main processing unit and the interface; a first data storage device for storing, in a first form, data representing an image to be printed; a second data storage device for storing data representing an image to be printed in a second form suitable for transmission to the marking engine; a data block moving device for controlling the transfer of data from the first data storage device to the second data storage device while the data is converted from the first form to the second form; a second bus structurally separate from the main bus and interconnecting the first data storage device, the second data storage device and the data block moving device; and a signal transmitting device connected between the main bus and the second bus for permi

Abstract: The present invention provides a novel ink jet ink which is semi-solid at room temperature. The subject ink combines the advantageous properties of thermal phase change inks and liquid inks. More particularly, the inks of the present invention comprise vehicles, such as glyceryl esters, polyoxyethylene esters, waxes, fatty acids, and mixtures thereof, which are semi-solid at temperatures between 20.degree. and 45.degree. C. *The ink is impulse jetted at an elevated temperature in the range of above 45.degree. C. to about 110.degree. C., at which temperature the ink has a viscosity of about 10-15 centipose. The subject inks exhibit controlled penetration and spreading, but do not remain on the surface of most substrates where they would be prone to burnishing, cracking or flaking. *These inks further comprise 0.1 to 30 wt. % of a colorant system.

Abstract: Novel impulse ink or bubble jet inks are disclosed which comprise 90-99.9% by weight of aqueous sol-gel medium and 0.1-10% by weight colorant. The inks are thermally reversible sol-gels which are gels at ambient temperatures and sols at temperatures between about 40.degree.-100.degree. C.

Abstract: A method of operating a system for jetting phase change ink comprises effecting a solid to liquid phase transition of the ink by elevating its temperature, ejecting a first volume of liquid ink towards a target, lowering the temperature of the ejected ink to cause it to solidify after contact with the target and the contacting the first volume of ink with a second volume of similarly jetted ink in a liquid state so that the two volumes are superimposed. Thereafter, the second volume of ink is caused to undergo a liquid to solid transition by lowering its temperature.

Abstract: An electro-expulsive apparatus including at least two superposed, flexible flat, separately jacketed continuous ribbons of metallic electrical conductor disposed within a sealed outer jacket so that portions of said separately jacketed electrical conductors are separable within said outer jacket to create a void when said conductors are energized simultaneously by an electrical current. The disclosure also includes restoring means for returning the separated conductors to rest position and a method of expulsing solid or frangible material.

Abstract: An ink jet apparatus having a scanning head employing at least one ink jet with a variable volume chamber which includes an ink droplet ejecting orifice, and a transducer, having a length mode resonant frequency, adapted to expand and contract along an axis of elongation in response to an electric field substantially transverse to the axis of elongation for ejection of droplets on demand from the ink droplet ejecting orifice is acoustically microstreamed by exciting the transducers during non-printing periods to eliminate start-up problems and to maintain pigments or other particles in dispersion within the ink.