# US 9,434,156 B2 · Method of inkjet printing and maintaining nozzle hydration

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- Number: US 9,434,156 B2
- Document ID: US9434156B2
- Status: Granted
- Kind: B2
- Application number: 14/550,810
- Filed: 2014-11-21
- Published: 2015-07-23
- Granted: 2016-09-06
- Earliest claimed: 2011-09-21
- Assignees: Memjet Technology Limited
- Applicants: Memjet Technology Ltd.
- Inventors: Angus North; Philip Palma; Brian Brown; Duncan McRae; Jognandan Prashar; Mile Jurevic; Sam Mallinson; Geordie McBain; Chia-An Lin; Sam Myers; Jeff Tsang; Benjamin Powell
- Web page: https://patentgrep.com/patent/US9434156B2

## CPC

- B41J 2/04513: {for increasing lifetime}
- B41J 2/0451: {for detecting failure, e.g. clogging, malfunctioning actuator}
- B41J 2/04536: {using history data}
- B41J 2/04551: {using several operating modes}
- B41J 2/14016: {Structure of bubble jet print heads}
- B41J 2/14145: {Structure of the manifold}
- B41J 2/155: for line printing
- B41J 2/16579: {Detection means therefor, e.g. for nozzle clogging}
- B41J 2/16585: {for paper-width or non-reciprocating print heads}
- B41J 2/175: Ink supply systems {; Circuit parts therefor}
- B41J 11/001: {Handling wide copy materials}
- B41J 2/16529: {Idle discharge on printing matter}
- B41J 2002/16591: {for line print heads above an endless belt}
- B41J 2202/20: Modules
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS

## Abstract

A method of printing from a fixed inkjet printhead having a plurality of ink planes. The method includes the steps of: feeding a print medium past the printhead in a media feed direction, the media feed direction defining relative upstream and downstream sides of the printhead; printing an image onto the print medium, the image being defined by image data; and printing a keep-wet pattern onto the print medium from each ink plane of the printhead, the keep-wet pattern being defined by a plurality of dots printed at a frequency sufficient to maintain hydration of each nozzle in the printhead. A first keep-wet pattern from a first ink plane is printed at a higher frequency than a second keep-wet pattern from a second ink plane, the first ink plane being furthest upstream in the printhead.

## Claims

### Claim 1

A method of printing from a fixed inkjet printhead having a plurality of ink planes, the method comprising the steps of:
feeding a print medium past the printhead in a media feed direction, the media feed direction defining relative upstream and downstream sides of the printhead;
printing an image onto the print medium, the image being defined by image data; and
printing first and second keep-wet patterns onto the print medium from respective first and second ink planes of the printhead, the keep-wet patterns being defined by a plurality of dots printed at a frequency sufficient to maintain hydration of each nozzle in the printhead,
wherein the first keep-wet pattern from the first ink plane is printed at a higher frequency than the second keep-wet pattern from the second ink plane, the first ink plane being furthest upstream in the printhead and in a relatively more dehydrating local environment than the second ink plane, and wherein a distance between neighboring ink planes in the printhead is in the range of 20 to 1000 microns.

### Claim 2 (depends on 1)

The method of claim 1, wherein each ink plane comprises one or more nozzle rows, each nozzle row within one ink plane being supplied with the same ink.

### Claim 3 (depends on 1)

The method of claim 1, wherein each nozzle of the printhead fires at a frequency of less than 0.5 Hz during each print job, either by virtue of printing the image or by virtue of printing the keep-wet pattern.

### Claim 4 (depends on 1)

The method of claim 1, wherein the keep-wet patterns each comprise a pseudo-random pattern of dots which is substantially invisible to an unaided human eye.

### Claim 5 (depends on 1)

The method of claim 1, wherein the printhead comprises a third ink plane positioned between the first and second ink planes, the third ink plane printing a third keep-wet pattern.

### Claim 6 (depends on 5)

The method of claim 5, wherein the third keep-wet pattern is printed at a lower frequency than the first and second keep-wet patterns.

### Claim 7 (depends on 5)

The method of claim 5, wherein the printhead is a multi-color printhead.

### Claim 8 (depends on 7)

The method of claim 7, wherein the first ink plane ejects yellow ink.

### Claim 9 (depends on 7)

The method of claim 7, wherein the third ink plane is ejects black ink.

### Claim 10 (depends on 1)

The method of claim 1, wherein the printhead is a monochrome printhead.

### Claim 11 (depends on 1)

The method of claim 1, further comprising the steps of:
receiving image data for a print job in a printer controller;
retrieving keep-wet pattern data for each ink plane of the printhead, the retrieved keep-wet pattern data being determined using one or more input parameters;
generating first print data for each ink plane of the printhead in the printer controller based on the received image data;
merging the first print data with respective keep-wet pattern data for each ink plane to provide second print data for each ink plane of the printhead; and
sending the second print data, or third print data comprising processed second print data, from the printer controller to the printhead, thereby causing the printhead to print the image together with a respective keep-wet pattern from each ink plane.

### Claim 12 (depends on 11)

The method of claim 11, wherein the step of merging the first print data with the keep-wet pattern data comprises ORing the first print data with the keep-wet pattern data.

### Claim 13 (depends on 12)

The method of claim 12, further comprising the step of applying an offset to the keep-wet pattern data before merging with the first print data.

### Claim 14 (depends on 13)

The method of claim 13, wherein a different offset is applied for different pages.

### Claim 15 (depends on 11)

The method of claim 11, wherein the image data is received from a computer system programmed with a printer driver for the printhead.

### Claim 16 (depends on 15)

The method of claim 15, wherein the printer controller retrieves the keep-wet pattern data from the printer driver.

### Claim 17 (depends on 11)

The method of claim 11, wherein the printer controller comprises a memory storing a plurality of different keep-wet pattern data, and wherein the printer controller retrieves the keep-wet pattern data for the print job from the memory.

### Claim 18 (depends on 11)

The method of claim 11, wherein the keep-wet pattern data for each ink plane is determined using one or more additional parameters selected from:
a print speed of the print job;
a type of ink printed from each ink plane;
a type of print medium;
a length of the print job;
an ambient humidity;
an ambient temperature;
the image content;
optical interference between keep-wet patterns printed from each ink plane; and
a minimum print quality threshold.

### Claim 19 (depends on 18)

The method of claim 18, wherein the keep-wet pattern for each ink plane is determined by an algorithm, the algorithm weighting said one or more parameters to determine the keep-wet pattern.