Francis E Bockman

US Patent:

6431679, Aug 13, 2002

Filed:

Apr 4, 2000

Appl. No.:

09/543162

Inventors:

Guo Li - San Diego CA
David Charles Towery - San Diego CA
Francis Bockman - San Diego CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

B41J 201

US Classification:

347 19

Abstract:

The present invention is embodied in a system and method for automatically calibrating the print contrast of an inkjet printing system using an optical-electronic sensor to detect an ink drop volume. The print contrast calibration system includes an optical-electronic sensor that obtains test pattern data from a printed test pattern, a calibration module that contains calibration data for the printing system, an installation module that determines a drop volume score by using the test pattern data and the calibration data and a printing module that determines a print contrast setting based on the drop volume score. The present invention also includes a method for calibrating print contrast in a printing system by storing standard calibration curves for the printing system, comparing the standard calibration curves with a printhead assembly calibration curve to determine a drop volume score, and setting the print contrast based on the drop volume score.

US Patent:

60828498, Jul 4, 2000

Filed:

Mar 10, 1997

Appl. No.:

8/814949

Inventors:

Michael Ming Hsin Chang - San Diego CA
Francis Edward Bockman - San Diego CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

B41J 221
B41J 2938
B41J 29393

US Classification:

347 43

Abstract:

One form of the printer inks multiple tonal levels, as for continuous-tone images. A generally randomized printmask controls the printer. What is randomized is, for each pixel respectively, an indicator of whether to print or not. Each indicator is, preferably, a discriminator number for comparison with desired-image data--specifically with a desired tonal level, at each pixel, for the desired color image--to make each printing decision. Preferably the printer is thereby deciding whether to deposit a certain number of drops per pixel; it compares the discriminator with a particular number of desired drops, for the desired image. The discriminator at each pixel is in general different for multiple passes and these discriminators for the passes form a sequence. The sequence, for each pixel. , is preferably selected at random from a multiplicity of sequences.

US Patent:

62609483, Jul 17, 2001

Filed:

Aug 18, 1999

Appl. No.:

9/378165

Inventors:

Guo Li - San Diego CA
Francis E Bockman - San Diego CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

B41J 221
B41J 29393

US Classification:

347 43

Abstract:

Incremental printing apparatus preferably includes a system for steering the error-diffusion system to respond, to a near-gray or near-yellow input color, with a preselection of a color toward one color plane or toward another color plane. This is not a threshold system. Preferably the steering system operates toward one of the color planes depending on which plane is closer to an input color signal (which includes accumulated error from pixels processed previously, as well as the original signal for a pixel being processed). Preferably the apparatus essentially forecloses use of different inks in adjacent pixels, as distinguished from only modifying a likelihood of using different inks. Preferably the system operates in particular portions of color space that are near a yellow axis. Preferably the two color planes are a cyan and a magenta plane.

US Patent:

6081344, Jun 27, 2000

Filed:

Oct 30, 1997

Appl. No.:

8/960779

Inventors:

Francis E. Bockman - San Diego CA
Guo Li - San Diego CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

G06F 1500

US Classification:

358 19

Abstract:

A halftoning technique is disclosed which uses look-up tables to identify a combination of color ink drops (device states) to be printed by an inkjet printer. The look-up tables are indexed by a particular color to be reproduced. An error is also output by the look-up tables reflecting the difference between the indexing tone level and the printed color spot. The error is applied in a halftoning process to neighboring pixels. A plurality of look-up tables is used, and one of the look-up tables is selected for a particular medium (e. g. , glossy paper, plain paper) to be printed upon. In this manner, the number and combination of ink drops can be optimize for a particular type of medium. In one embodiment, six different color inks are used by the printer.

US Patent:

60300663, Feb 29, 2000

Filed:

Oct 31, 1997

Appl. No.:

8/961730

Inventors:

Guo Li - San Diego CA
Francis E. Bockman - San Diego CA
Joseph M. Torgerson - Philomath OR

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

B41J 29393

US Classification:

347 19

Abstract:

A method, for adjusting the color balance of printheads in a color printer, utilizes a matrix of image data including a reference image data set for a reference image and a plurality of color modified image data sets for plural color modified images. The reference image data set includes in-balance component color data values and each of the color-modified image data sets include out-of-balance component color values. A printer is controlled to operate the printheads to print the reference image and each of the color modified images at pre-determined locations on a media sheet in accord with the matrix of image data. If the printheads are not properly adjusted, the printed reference image and each of the color modified images appear positionally offset on the media sheet. A user, upon examining the media sheet selects one image on the media sheet as the reference image (e. g. , the image which exhibits best black/white characteristics and contrast).

US Patent:

55109101, Apr 23, 1996

Filed:

May 3, 1994

Appl. No.:

8/238118

Inventors:

Francis E. Bockman - San Diego CA
Paul H. Dillinger - San Diego CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

H04N 146

US Classification:

358502

Abstract:

A technique of merging or "matching" hue pages of a CRT and printer is used to map CRT control signals through a common perceptual space into printer control signals. The system (1) receives a color specification expressed as CRT control signals, (2) locates the specified color within the CRT perceptual gamut, (3) normalizes the two gamuts in perceptual space, (4) determines the relative position of the same color in the normalized CRT gamut, (5) declares that position to be the relative position of that color in the normalized printer gamut as well, (6) unfolds the normalization to determine the absolute position of the color in the actual printer gamut, (7) expresses that position in terms of printer-control signals, and then (8) applies those signals to the printer, to print the specified color. As a result that color, and color changes, specified in terms of CRT control signals are tracked in terms of both printer control signals and actual printer performance. The two device gamuts are in effect mapped to each other; the full gamuts of both are in effect merged.

US Patent:

61794074, Jan 30, 2001

Filed:

Nov 20, 1998

Appl. No.:

9/197291

Inventors:

Francis E. Bockman - San Diego CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

B41J 2145
B41J 215
B41J 2300
B41J 29393

US Classification:

347 40

Abstract:

An inkjet color printer accesses image data to be printed on a pixel by pixel basis and determines the Z number of drops of different color inks to distribute per pixel over a predetermined number of passes in a multi-pass print mode of operation. Predetermined constraints relative to the maximum number of drops of a single ink color per pixel and per pass permit maskless drop ordering and an even distribution of ink over time per pixel.

US Patent:

61780081, Jan 23, 2001

Filed:

Oct 30, 1997

Appl. No.:

8/960766

Inventors:

Francis E. Bockman - San Diego CA
Guo Li - San Diego CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

G06K 1500

US Classification:

358 19

Abstract:

An automatic system forms color LUTs (or LUT-forming data) for automated reference--typically in error diffusion (ED). A first aspect is for printers with six or more colorants. Three ramps, for different basic colorants, are photometrically measured; mainly just those results yield a transform from 3D color to system colorants. In a second aspect, some device-state candidate colors are chosen for black replacement. In a variant the choice is subject to (1) maintaining some chromatic colorant in each pixel with black; or (2) modifying use patterns to avoid alternative use of composite black vs. black; or (3) adjustments to allow for composite nonequivalence to black. A related third aspect allows replacement only if there is a given minimum amount of composite. In a fourth aspect, candidate states are dropped that have small changes in number of quanta per pixel, or no companion light colorant quantum with each dark one, best eliminating those with too many quanta of each or all colorants. In a related fifth aspect, one state is assigned to each major entry based on, at a gamut surface except at the dark end, favoring states nearer the surface over those nearer a desired major entry; and at the neutral axis, especially its dark end, favoring real black.