International Business Machines Corporation

Ricoh Production Print Solutions LLC

James Francis Crossland

Joan LaVerne Mitchell

Wayne T Comeaux

Robert C Baca

Nenad Rijavec

Alex Chliwnyj

John Alexander Koski

Kartheek Chandu

James A Bailey

James E Smith

James Ernest Malmberg

Don G East

Ronald K Rhodes

Yogesh B Patel

Gary R Williams

Man F Cheung

Maxey P Von Senden

Alex Chliwnyjae

Systems and methods of printing to a tangible medium provide for reducing ink penetration via the controlled selection of halftone patterns. One method includes steps of printing to the tangible medium (e.g., via a multicolor ink supply such as CMYK) using a plurality of initial halftone patterns, measuring ink absorption of the tangible medium in response to printing to the tangible medium, and determining a subset of the plurality of initial halftone patterns based on the absorption measurement. The method also includes printing a print job to the tangible medium based on the subset of the plurality of initial halftone patterns. For example, a print controller may be reprogrammed with the subset of the plurality of initial halftone patterns to print a print job to reduce the amount of ink applied to the tangible medium.

Printing with alternative halftone patterns in ink jet printing to reduce ink penetration

Apparatus and method for flexible digital halftoning are provided in which novel pattern choices are allowed by not restricting the basic halftone patterns to grow sequentially. Rather, positions in a threshold array allow multiple transitions between on (i.e., printed with toner/ink) and off (not printed) as a function of the input value at the corresponding position. In one embodiment, multiple threshold matrices are employed and the output decision is a vote (e.g., exclusive OR) of the outputs of the individual threshold matrices. In another embodiment, each position contains an arbitrary bit vector to express the output for each input. This flexibility in growing basic halftone patterns allows the number of densities output to be larger than n+1 (where 'n' is the number of dots within a basic halftone cell).

Halftoning method and system providing increased number of densities per basic halftone cell for constant input

Apparatus and methods for flexible digital halftoning are provided in which novel pattern choices are allowed by not restricting the basic halftone patterns to grow sequentially. Rather, positions in a threshold array allow multiple transitions between on (i.e., printed with toner/ink) and off (not printed) as a function of the input value at the corresponding position. In one embodiment, multiple threshold matrices are employed and the output decision is a vote (e.g., exclusive OR) of the outputs of the individual threshold matrices. In another embodiment, each position contains an arbitrary bit vector to express the output for each input. In yet another embodiment, space efficiency may be achieved by sorting the arbitrary bit vectors into collections of adjacent decisions for a given input value, such as into bytes.

Flexible digital halftoning

The present invention provides an apparatus and method for initializing a magnetic tape when it is mounted in a tape drive. In one embodiment, each time a tape is mounted, control parameters pertaining to the servo system are set to predetermined values and servo read elements in the tape head are activated. The tape is moved and a number of position error signal (PES) samples are read and averaged for each of the active servo elements. The value of one or more of the parameters is modified and new PES readings and averages are obtained. This process is repeated for a predetermined combination of parameter values whereupon read and write offsets are calculated and stored for each servo element. During an actual read (or write) operation, the tape head is positioned relative to the data tracks on which the desired data is located and servo control enabled. An actual PES generated by each active servo element is adjusted by the read (or write) offset calculated for that servo element, thereby substantially canceling the effects of element-to-element, module-to-module and azimuthal deviations. The resulting adjusted PES is used by the servo controller to optimize track following.

Initialization and calibration of magnetic tape having multiple servo

In a magnetic tape drive, a magnetic head simultaneously senses plural track lateral position indicators to generate a like plurality of independently generated sensed position error signals. The sensed position error signals are combined to provide an output position error signal that drives a positioning system to position the magnetic laterally of the length of the magnetic tape. The output position error signal represents an average of the position errors indicated by the sensed position error signals. The quality of the sensed position error signal is monitored, enabling eliminating poor quality signals from the output position error signal for maintaining a quality servo control. If less than a predetermined number of sensed position error signals have acceptable quality, then recording data is prohibited. Independently of sensing servo indicia on a record member to generate the sensed position error signals, a lateral position of the multi-track head is sensed. Upon loading the record member to a load point, the plural track position indicators are simultaneously sensed for centering the head to a predetermined track position. Then, an independent head position sensor is calibrated to the load point track position indicators for use as a verification of validity of the output position error signal. During recording and reading operations, the independent head position is determined on a periodic basis. If an unacceptable change in head position during any measurement period occurs or if the independent measurement indicates an unacceptable lateral deviation from the reference position, all recording is prohibited.

Processing servo signals concurrently read from plural spaced-apart

The present invention provides an apparatus and method for precise servo tracking of a multi-track magnetic tape head. The magnetic tape has at least one servo area with at least two servo tracks. Adjoining servo tracks have different servo patterns recorded thereon, one being a single frequency, constant amplitude signal, the other alternating between a zero amplitude null signal and a constant amplitude signal of a second frequency. A servo element in the tape head senses and combines the signals from both of the tracks. A detector outputs the peak-to-peak amplitude values of the combined signal and two register modules detect and store the maximum and minimum peak-to-peak values over a predetermined period of time. These maximum and minimum values are provided to a signal processor which determines their ratio. The ratio indicates the amount and direction of any position error of the servo element relative to the edge between the two adjacent servo tracks and is used to direct an actuator to adjust the position of the tape head to minimize the error.

Track following servo demodulation

The present invention provides a method and system for generating a position error signal from a signal produced by a read element detecting a track comprising two harmonically unrelated patterns positioned parallel to each other on a magnetic media. The apparatus of the present invention produces a delayed signal from the read signal produced by the read element. The read signal is multiplied with the delayed signal to form a product signal. The product signal is integrated to produce a position error signal, wherein changes in the position error signal that are proportional to changes in position of the read element over the two patterns positioned parallel to each other on the magnetic media.

Growing community of inventors

Boulder, CO, United States of America

James Francis Crossland