Abstract: A method and apparatus of printing with a liquid ink printhead ejecting ink in swaths on a recording medium to form an image including a plurality of dots deposited at pixel locations of a scanline. The printer deposits a plurality of dots at adjacent pixel locations on the scan line during non-consecutive swaths of the printhead to form the image. Dot interaction between dots is minimized so that no two dots are deposited adjacent to each other in consecutive depositions of the dots of consecutive swaths of the printhead. Reduction of ink bleeding, printhead signatures such as banding, and other defects caused by clogged nozzles of the printhead are reduced.

Abstract: A method and apparatus for converting an input image including a plurality of input pixels each having a number of possible input levels of optical density to an output image including a plurality of output pixels each having a number of possible output levels of optical density using phantom output levels in an error diffusion technique, an automatic image enhancement technique, or other printing methods and apparatus where errors are fed back to alter an input image. The method includes generating a modified optical density value by adding an error value, if any, to the input level of one of the input pixels, generating a phantom output level as a function of the modified optical density level, determining the error value as a function of the selected phantom output level; and generating an output pixel having one of the output levels determined as a function of the modified optical density value.

Abstract: A printing apparatus and method for printing on a recording medium at locations being determined by encoder pulses of an encoder signal generated by an encoder including an encoder pending circuit. The encoder pending circuit outputs an encoder pending signal indicating the generation of one of the encoder pulses during a current printing operation. A controller coupled to the encoder pending circuit, receives the encoder pending signal and generates an enable signal after the completion of the current printing operation. The method of printing includes receiving one of the encoder pulses; determining whether the received one of the encoder pulse is generated during a current printing operation and completing the current printing operation before responding to the received one of the encoder pulses.

Abstract: A method for processing an input image including a plurality of input pixels each having a first number of possible input levels of optical density to form an output image including a plurality of separations each including a plurality of output pixels each having a second number of possible output levels of optical density.

Abstract: A liquid ink printing method having region dependent image processing for printing a color image with a liquid ink printer, having a printhead, from image information generated by an image source. The method includes generating a plurality of bitmaps from the image information, examining a corresponding portion of each of the plurality of bitmaps for color information, and applying color image processing to only the examined corresponding portion having color information. The method of printing, including region dependent image processing, improves performance of complex image processing operations by detecting and tagging portions of an image which require the complex image processing operations. Only those regions that require complex image processing operations are processed according to those processes and other information, such as text, are not processed.

Abstract: A method and apparatus for drying liquid ink deposited, in response to image data, on a recording medium moving along a path at a predetermined rate. A recording medium having liquid ink deposited thereon is moved past a dryer in multiple passes to dry areas of high ink coverage. Ink characteristics are optimized for minimum print defects by determining the time between printing and drying. In the case of text only images only one pass through the dryer is required. For areas of high ink coverage, however, multiple passes through the dryer are required and completed either by reciprocation or recirculation at the same predetermined rate.

Abstract: A liquid ink printer forming images on a recording medium including a liquid ink printhead movable between a printing position and a maintenance position and a maintenance arrangement, located at the maintenance position, including a driver, a first mechanism, and a second mechanism. The driver is coupled to the first mechanism and to the second mechanism and moves in a first direction to actuate the first mechanism and in a second direction to actuate the second mechanism. The driver includes a stepper motor having a single shaft coupled to the first mechanism and to the second mechanism through a unidirectional clutch. The first mechanism, such as a cam bank or rotary valve, is actuated by the stepper motor moving in a first direction, and the second mechanism, such as a vacuum pump is actuated by the stepper motor moving in a second direction.

Abstract: A large array or pagewidth printhead fabricated from printhead elements or subunits. The printhead subunits are butted together at either adjacent channel elements or adjacent heater elements to form a pagewidth printhead. The butting element, either heater or channel element, is slightly wider than the non-butting element thereby providing gaps between the non-butting elements of a printhead element array. Where channel elements are used as the butting element, gaps between the heater elements provide for reduction or elimination of potentially damaging thermal compressive forces between adjacent heater elements. Where heater elements are used as the butting element, structural strength is increased since the heater wafer is stronger than the channel wafer. In addition, the width of the polyimide wall at the edges of the heater wafer is increased providing greater protection for thermal transducers located at the edges of individual heater elements.

Abstract: A printing machine having a dryer for drying liquid ink printing deposited in a print zone on a surface of a recording medium moving along a path. The dryer includes a heat source, generating heat energy, disposed adjacently to the path, for heating the recording medium and drying the ink. A reflector system, including a first reflector and a second reflector, direct the heat energy toward another surface of the recording medium. In one embodiment, the heat source comprises a quartz tube having a reflective coating, acting as the first reflector, deposited on a surface of the tube, and the second reflector directs additional heat energy towards the recording medium.

Abstract: A method of controlling the operation of an ink jet printhead having a burn voltage applied to a transducer nucleating an ink bubble to cause an ink droplet to be ejected from an ink ejecting orifice. The method includes determining a threshold power dissipated by the transducer sufficient to cause the bubble to nucleate, the threshold power being determined by a firing pulse having a pulse length and a threshold voltage, selecting the pulse length of the firing pulse to be approximately equal to a pulse length necessary to achieve the highest effective power dissipation in the transducer, and selecting the burn voltage as a function of the threshold voltage. Changes to the threshold power dissipated by the transducer necessary to eject from the ink ejecting orifice are determined and the pulse length of the firing pulse is adjusted accordingly.

Abstract: A method for processing an input image including a plurality of input pixels each having a first number of possible input levels of optical density to form an output image including a plurality of separations each including a plurality of output pixels each having a second number of possible output levels of optical density.

Abstract: A printing machine of the type in which liquid ink is deposited on a recording medium for printing gray scale images. The printing machine includes a printhead having ink ejecting nozzles of different sizes. Nozzles of the same size are arranged in groups and groups of nozzles are offset from one another. Ink drops of one group are deposited at locations corresponding to the points of a grid and ink drops of another group are deposited at locations corresponding to points not on the grid. Gray scale printing is achieved by the variation in drop size produced by different groups of nozzles as well as offsetting nozzles of one or more groups of nozzles from a reference group of nozzles printing on the points of a grid.

Abstract: An ink jet printhead cartridge having a fluid valved breather. The ink jet printhead cartridge includes a housing having an air inlet, an ink outlet, a first chamber, and a second chamber. The first chamber contains a supply of ink and is substantially free of ink-retaining foam. The second chamber includes an ink-retaining foam which saturates with ink for supply to an ink jet printhead. An air transfer passageway connects the first chamber to the second chamber so that air pressure affects the level of ink in the first chamber thereby maintaining a level of ink in the second chamber sufficient for supplying ink to the ink jet printhead.

Abstract: A segmented flexible heater disposed adjacently to a paper path in a printing machine for heating a recording medium before printing and during printing. The segmented flexible heater includes a curved first portion for preheating the paper and a substantially planar second portion for heating the paper in a print zone wherein the second portion generates heat energy having a temperature greater than the heat energy generated by the first portion. The first portion includes apertures for accommodating drive rollers for moving the recording medium into the print zone area heated by the second portion. The apertures in the flexible heater provide for continuous heating of the recording medium before and during heating. The second portion is preferably at least two printing swaths wide to prevent thermal shock to the portion of the printing medium being printed on.

Abstract: A method for electrical tailoring of thermal ink jet heater elements. The resistance of ink-jet heater elements formed of polysilicon is changed by applying energy through the resistor element of varying amounts at varying pulse widths. The application of pulsed current for up to 1 second total pulse width at voltages of up to 50 volts decreases the resistance by as much as thirty percent or more of the as fabricated values.

Abstract: A liquid ink printing apparatus printing images includes a printhead having a plurality of nozzles wherein a single power pulse causes two or more nozzles to eject ink simultaneously. The printhead includes an ink directing element having a plurality of ink conduits coupled to an array of spaced nozzles and a transducer element aligned with and mated to the ink directing element. The transducers are spaced a distance apart and each transducer is substantially aligned with at least two or more of the nozzles. The printhead is stepped in a direction transverse to the array of spaced nozzles a stepping distance approximately equal to or less than the distance between transducers. The ink directing element includes a silicon wafer having etched ink conduits or channels holding ink for ejection through the nozzles connected thereto.

Abstract: An ink detecting mechanism for a liquid ink printer including a liquid ink printhead having a plurality of ink carrying conduits terminated by an ink ejecting orifice. The ink detecting mechanism detects the presence of ink within the ink carrying conduits and includes a normally open circuit maintained in an open condition when said ink carrying conduit lacks the presence of ink. The fluid detecting device includes a detecting probe spaced from a transducer element located in the ink carrying conduit such that the presence of ink is detected for between the location of the detecting probe and the location of the transducer element. A signal is generated by a detection circuit for each of the channels of the printhead. Each signal is then summed and a decision signal is generated indicating whether or not the entire array of printhead nozzles should be primed. The detection of ink within the channels is performed without the need for ejecting ink from the channels.

Abstract: In a liquid ink printer transport belt located between a liquid ink printhead and a vacuum holddown device includes apertures for applying a vacuum to the recording medium and for enabling the liquid ink printhead to purge ink through the apertures in the absence of the recording medium without slowing or stopping the belt. The vacuum holddown device includes a platen located beneath the belt for applying a vacuum through the apertures and gutters or slots for collecting ink from the liquid ink printheads during printing. The combination of belt and platen or apertures and gutters or slots provides continuous communication of the vacuum to the recording media as the belt moves across the platen and through a dryer. The transport belt enables the use of a single transport for both imaging and drying.

Abstract: A transport system for transporting a recording sheet having liquid ink deposited thereon through a dryer for drying the liquid ink having an input portion and an output portion. The transport system includes a transport belt disposed between the input portion and the output portion for transporting the recording sheet through the dryer. A negative pressure member is located beneath the belt and defines a negative pressure chamber. The pressure member decreases the pressure within the pressure member so that a non-uniform negative pressure is applied to the recording sheet during transport through the dryer. A directing member located within a plenum directs differing negative pressures within the plenum such that negative pressures decrease in amplitude along the transport direction. The application of a negative pressure within the plenum also tends to reduce or remove evaporated liquid driven from the inks during drying.