Method and system for measuring drop-volume in ink-jet printers

Claim 3

A method according to claim 1 wherein the step of changing the number of ink drops comprises depositing fewer ink drops in subsequent print samples within the series so that the print samples experience progressively greater ink depletion from initial print samples of the series to later print samples of the series.

Claim 4

A method according to claim 1 wherein the printing step comprises printing a series of print samples according to a set of corresponding predefined print patterns, individual patterns defining a desired number and position of ink drops for associated individual print samples.

Claim 5

A method according to claim 1 wherein the step of analyzing the print samples comprises visually observing the series of print samples to detect changes in optical density.

Claim 6

A method according to claim 1 wherein the step of analyzing the print samples comprises optically scanning the series of print samples to detect changes in optical density.

Claim 7

A method according to claim 1 further comprising: forming a character within the individual print samples to define a first print sample area covered by the character and a second print sample area not covered by the character; and changing the number of ink drops deposited within the second print sample area to selectively deplete the second print sample area of ink.

Claim 10

A method according to claim 7 wherein the series of print samples formed in steps (a)-(c) are printed according to a set of predefined print patterns that define a number of ink drops deposited in the first and second print sample areas for sequentially deposited print samples.

Claim 11

A method according to claim 7 wherein steps (a)-(c) comprise forming a bar-shaped character; and step (d) comprises optically scanning the print samples containing the bar-shaped characters using an electronic optical scanning means.

Claim 12

An ink-jet printing system comprising: a platen; an ink-jet printhead disposed adjacent to, but spaced from, the platen to permit passage of a recording media therebetween, the ink-jet printhead having multiple nozzles for depositing drops of ink onto the recording media to form printed images; an optical sensor having a light source oriented to emit a light beam toward the platen and a light sensitive detector aligned to detect reflected light; a memory for storing a plurality of test print patterns which define a number and position of multiple ink drops to be deposited by the printhead, individual test print patterns having a character region and a depletion region whereby the number and position of ink drops to be deposited in the depletion regions vary among the test print patterns; the ink-jet printhead being operable during a test mode to print a series of print samples according to the test print patterns stored in the memory, individual print samples having first print sample areas that are representative of the character regions of the test print patterns and second print sample areas that are representative of the depletion regions of the test print patterns, the printhead depositing a substantially constant number of ink drops within the first print sample areas and a varying number of ink drops within the second print sample areas so that the second print sample areas experience selected varying degrees of ink depletion as compared to the first print sample areas; and the optical sensor being operable during the test mode to scan the print samples to detect changes in optical density between the first print sample areas and the second print sample areas.

Claim 13

An ink-jet printing system comprising: a platen; an ink-jet printhead disposed adjacent to, but spaced from, the platen to permit passage of a recording media therebetween, the ink-jet printhead having multiple nozzles for depositing drops of ink onto the recording media to form printed images; an optical sensor having a light source oriented to emit a light beam toward the platen and a light sensitive detector aligned to detect reflected light; a memory for storing a plurality of test print patterns which define a number and position of multiple ink drops to be deposited by the printhead, individual test print patterns having a character region and a depletion region whereby the number and position of ink drops to be deposited in the depletion regions vary among the test print patterns; the ink-jet printhead being operable during a test mode to print a series of print samples according to the test print patterns stored in the memory, individual print samples having first print sample areas that are representative of the character regions of the test print patterns and second print sample areas that are representative of the depletion regions of the test print patterns, the printhead depositing a substantially constant number of ink drops within the first print sample areas and a varying number of ink drops within the second print sample areas so that the second print sample areas experience selected varying degrees of ink depletion as compared to the first print sample areas; and the optical sensor being operable during the test mode to scan the print samples to detect changes in optical density between the first print sample areas and the second print sample areas.

Claim 14

An ink-jet printing system according to claim 10 further comprising: a carriage configured to move bidirectionally across the platen, the carriage being spaced from the platen to permit passage of the recording media therebetween; and the ink-jet printhead and the optical sensor being mounted to the carriage to be operatively positionable over the recording media.

Claim 15

An ink-jet printing system according to claim 10 further comprising: a processor operatively coupled to the optical sensor to derive a drop-volume for the ink-jet printhead based upon the optically detected changes in the scanned print samples.

Claim 16

An ink-jet printing system according to claim 10 further comprising: a processor operatively coupled to the optical sensor to derive a drop-volume for the ink-jet printhead based upon the optically detected changes in the scanned print samples; and a control subsystem connected to control operating parameters of the ink-jet printing system that relate to depositing ink drops onto the recording media, the control subsystem automatically adjusting the system parameters in response to the drop-volume derived by the processor to yield a desired drop-volume for the ink-jet printhead.