Hewlett-packard Company

Paul R Sorenson

Robert Warren Beauchamp

Keith E Cobbs

Christopher A Schantz

Todd A Fischer

Russell Campbell

James G Wendt

Patrick W Fulghum

An ink drop detector that minimizes costs of a printer by employing preexisting digital signal processing elements in a printer and low cost analog sensing elements. The analog sensing elements are tuned to ink drop bursts, which include a plurality of ink drops, and the preexisting digital signal processing elements extract ink drop characterization information from sensed analog signals.

Low cost ink drop detector

An improved image registration system for a multicolor inkjet printer/plotter. The inventive system comprises a carriage assembly for retaining multiple inkjet cartridges. Each cartridge has a plurality of nozzles adapted to eject ink in response to the application of an electrical signal thereto. A first mechanism is provided for moving said carriage assembly means in a first axis. A second mechanism is provided for moving print media in a second axis transverse to the first axis, said first axis being a scan axis and said second axis being a media axis. A first position encoder senses the position of the carriage assembly in the first axis and a second position encoder senses the carriage assembly in the second axis and providing position encoder signals in response thereto. A control circuit provides electrical signals which cause the nozzles in the inkjet cartridges to eject ink onto the media and create an image thereon in response to timing signals. The inventive system includes a sensor module which optically senses the image and provides a set of sensed signals in response thereto. The sensed signals are processed to provide timing signals for use in correcting the image misregistration.

Multiple inkjet print cartridge alignment by scanning a reference

A test pattern for use with an optical sensor for an inkjet printer. The inventive pattern comprises a first plurality of vertical bars horizontally spaced and a second plurality of horizontal bars vertically spaced. The spacing between the bars is approximately equal to the width of the bars. In a particular implementation, the pattern is adapted for use with an inkjet printer having a plurality of pens. The first plurality of bars includes a first set of bars printed by each of the pens. The first plurality of bars includes a second set of bars printed by one of the pens moving at at least two different horizontal speeds. The second plurality of bars includes one column of vertically spaced bars for each of the pens. Each column of vertically spaced bars includes a first plurality of vertically spaced bars printed by a first pen. A respective column of vertically spaced bars includes a second plurality of vertically spaced bars printed by a respective one of the pens. Each column of vertically spaced bars includes a third plurality of vertically spaced bars printed by the first pen. The inventive pattern allows for considerable information with respect to pen alignments to be determined by optical scanning.

Reference pattern for use in aligning multiple inkjet cartridges

A system for correcting for a time of flight delay of a drop of ink from an inkjet printhead. The inventive system includes a first mechanism for scanning the printhead along a first axis at a first velocity. A control circuit, responsive to inkjet timing signals, causes the printhead to eject ink onto a media to create a test pattern thereon as the printhead is scanned along the first axis. A sensor optically sense the test pattern and provides a time of flight dependent phase signal in response thereto. This signal is processed to provide time of flight delay corrected inkjet timing signals for the first velocity in response to the phase signal. In a particular implementation, the processor is adapted to add an additional delay to the corrected timing signals to correct for curvature.

Multiple inkjet cartridge alignment for bidirectional printing by

A packet-based communication system is described for linking a peripheral unit (PU) to the outside world via a communications link. The system includes a modular interface unit (MIU) which has a memory shared by processors in both the PU and MIU. The system employs control packets, read packets and write packets and performs a method for allocating the shared memory that optimizes memory utilization. The system determines a ratio of read to write packets required in the operation of the PU, and it ignores that ratio if the communications link will not transmit write packets. If the communication link will transmit write packets, it allocates read and write packet space within the shared memory in accordance with the ratio. The system also includes apparatus for enabling MIU configuration via user/keyboard inputs through the PU with the MIU providing the question and answer messages. This feature allows the PU to adapt to many different communication links, simply by replacement and user configuration of the MIU. The system further includes apparatus for rapidly handling network protocol headers. Those headers are stored along with the data packets and when the packet is accessed by the PU from shared memory, pointers are employed to enable access of only the data portions of such packets while ignoring the network protocol header portions.

Growing community of inventors

San Diego, CA, United States of America

Paul R Sorenson