Hewlett-packard Company

Albert Serra

Jose Julio Doval

Stefano Schiaffino

Xavier Girones

Xavier Gros

Ronald Albert Askeland

Antoni S Murcia

Clayton L Holstun

Xavier Bruch

Ramon Vega

Eric Joseph Johnson

Francesc Subirada

Richard H Lewis

Paul David Gast

Miquel Boleda

Emilio Angulo

James L McCullough

Scott A Norum

Christopher C Taylor

Antoni Murcia Serra

Miguel Boleda

An improved apparatus for checking a plurality of printer nozzles in a printer device comprises: a printer head comprising a plurality of nozzles; a device for detecting at least one droplet of ink sprayed from at least one nozzle of said plurality of nozzles; and a device for performing a sequence of measurements on a first output signal of the detecting device, wherein a determination of performance of the print head is made by analyzing detected output signals produced by one or a plurality of ink droplets passing the detector, the one or plurality of ink droplets containing a predetermined minimum volume of ink, and the sequence of measurements being measured at a plurality of time intervals.

Method for detecting drops in printer device

A calibration technique, for a printer having a plurality of different color ink printheads, which includes printing and scanning a test pattern. The test pattern is printed by each printhead printing a plurality of swaths having a length and distanced apart from each other. An optical sensor is used to scan the printed test pattern. Calibration is performed for each head by reading the swath length and the relative spacing of the swath and comparing the length to the spacing. This comparison is used to find the directional error for each head.

Compensation for marking-position errors along the pen-length direction, in inkjet printing

A misalignment compensation technique for a dot printer is disclosed. This technique first supplies printing instructions to a printhead for energizing printing elements in various groups (primitives) to print a pattern on a medium. The printed pattern is then detected by optical sensors in the printer. Based on the detection, a position offset error for each primitive is determined. These errors are used to generate a separate time correction for each of the primitives such that, when the printer is used normally, the time period for printing a dot will be advanced or delayed for each primitive so as to align the dots printed by the primitives. In another embodiment, alignment data taken by a manufacturing line sensor is stored in a memory on the print cartridge. After the print cartridge is installed in the printer, a second optical test completes the data needed to create timing correction values.

Alignment of ink dots in an inkjet printer

A method and apparatus for correcting for drop placement errors due to relative rotation between an inkjet printhead mounted in a printer carriage and the print media to be printed on comprises first determining the relative contribution to the drop placement error due to rotation of the printhead about the scan axis (Y axis error), then, with respect to any determined Y axis error, applying the same magnitude and sense of correction for drop placement errors while printing in both a first scanning direction of the carriage and while printing in a second scanning direction of the carriage. Errors due to rotation about the Z axis are also corrected for. Preferably the errors are determined by printing and scanning a test pattern.

Correction system for droplet placement errors in the scan axis in inkjet printers

Techniques to compensate for random and systematic errors when measuring dot placement errors. Error accumulation due to scan axis irregularities during printhead calibration is minimized by swapping alignment block positions on the print medium from swath to swath. Print media advances during the calibration are minimized by the use of a moving reference instead of a constant reference; adjacent groups of nozzles are used to calibrate the following group. Only a small media advance is needed to print alignment blocks using adjacent nozzle groups one beside the other to be calibrated. To prevent paper slip accumulative errors when using moving references, the order of the groups of nozzles is swapped from one paper advance to the other. This randomizes for small, unavoidable slips when advancing the paper and prevents error accumulation. No further paper advances are used at all for the rest of the dot placement calibration (odd to even columns in a print-head, pen to pen correction and bidirectional correction). When calibrating X-axis position for a group of nozzles, a group of nozzles located at the same Y-axis coordinate is used, so that no paper advances are needed to print them one beside the other.

Techniques for robust dot placement error measurement and correction

A printer apparatus and method of actuating a fluid pump in a printer to deliver fluid to an ink jet printhead without removing the printhead from a printhead carriage particularly useful for priming inkjet printheads using an air displacement pump to deliver air under positive pressure to the printheads. The pump is located proximate a service station on the printer and is automatically actuated by movement of the carriage to service station. The pump may be arcuately positionable to align the pump with a selected one of air passageways provided in a printhead holddown cover on the printhead carriage. Algorithms are provided for locating the precise position of the pump outlet along the carriage scan axis relative to its intended design location and for arcuately positioning the pump relative to the carriage to engage the pump outlet with a selected one of conduits in the carriage connected to each printhead.

Method and apparatus for actuating a pump in a printer

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Barcelona, Spain

Albert Serra