# US 2018/0017882 A1 · Reducing contamination

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- Number: US 2018/0017882 A1
- Document ID: US20180017882A1
- Status: Published application
- Kind: A1
- Application number: 15/545,939
- Filed: 2015-04-01
- Published: 2018-01-18
- Earliest claimed: 2015-04-01
- Assignees: HP Indigo B.V.
- Applicants: HP Indigo B.V.
- Inventors: Kobi Shkuri; Sasi Moalem; Reut Diamant; Yossi Cohen; Shahar Tal
- Web page: https://patentgrep.com/patent/US20180017882A1

## CPC

- G03G 5/08214: {Silicon-based}
- G03G 9/0812: {Pretreatment of components}
- G03G 15/0887: {Arrangements for conveying and conditioning developer in the developing unit, e.g. agitating, removing impurities or humidity}
- G03G 15/0894: {Reconditioning of the developer unit, i.e. reusing or recycling parts of the unit, e.g. resealing of the unit before refilling with toner}
- G03G 15/10: using a liquid developer
- G03G 15/104: {Preparing, mixing, transporting or dispensing developer}
- G03G 21/0088: {removing liquid developer}
- G03G 21/0094: {fatigue treatment of the photoconductor}
- G03G 2215/018: Linearly moving set of developing units, one at a time adjacent the recording member
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

In an example of a method for reducing contamination, a purified imaging oil is formed by filtering an imaging oil through an imaging oil filter, and then filtering the imaging oil through a polar absorbent filter. A surface of an amorphous silicon photoconductor of a liquid electrophotographic printing apparatus is maintained by periodically applying the purified imaging oil to the amorphous silicon photoconductor.

## Claims

### Claim 1

A method for reducing contamination, the method comprising:
forming a purified imaging oil by:
filtering an imaging oil through an imaging oil filter; and
then filtering the imaging oil through a polar absorbent filter; and
maintaining a surface of an amorphous silicon photoconductor of a liquid electrophotographic printing apparatus by periodically applying the purified imaging oil to the amorphous silicon photoconductor.

### Claim 2 (depends on 1)

The method as defined in claim 1 wherein prior to the periodically applying, the method further comprises determining that a contamination level of the purified imaging oil ranges from 0 pico Ohms/cm up to 10 pico Ohms/cm.

### Claim 3 (depends on 1)

The method as defined in claim 1 wherein the periodically applying occurs prior to a charging portion of each printing cycle of the liquid electrophotographic printing apparatus.

### Claim 4 (depends on 1)

The method as defined in claim 1, further comprising:
removing some of the purified imaging oil from the amorphous silicon photoconductor, wherein the removed purified imaging oil includes at least some fluid residue from the amorphous silicon photoconductor, thereby cleaning the amorphous silicon photoconductor; and
performing a print cycle.

### Claim 5 (depends on 1)

The method as defined in claim 1 wherein:
the imaging oil filter is a mechanical filter of 2 micron particles; and
the polar absorbent filter is a silica gel filter or a carbon filter.

### Claim 6 (depends on 1)

The method as defined in claim 1, further comprising performing a full cleaning procedure at least 200,000 print cycles after an initial print cycle.

### Claim 7

A method for maintaining print quality of images printed with a liquid electrophotographic printing apparatus, the method comprising:
purifying an imaging oil by:
filtering the imaging oil through an imaging oil filter; and
then filtering the imaging oil through a polar absorbent filter, thereby forming a purified imaging oil;
detecting that a contamination level of the purified imaging oil ranges from 0 pico Ohms/cm up to 10 pico Ohms/cm;
applying the purified imaging oil to an amorphous silicon photoconductor of the liquid electrophotographic printing apparatus prior to a charging portion of a print cycle to remove residue from the amorphous silicon photoconductor, thereby forming a contaminated imaging oil; and
removing the contaminated imaging oil from the amorphous silicon photoconductor.

### Claim 8 (depends on 7)

The method as defined in claim 7, further comprising:
purifying the contaminated imaging oil by:
filtering the contaminated imaging oil through the imaging oil filter; and
then filtering the contaminated imaging oil through the polar absorbent filter, thereby forming a re-purified imaging oil;
detecting that a contamination level of the re-purified imaging oil ranges from 0 pico Ohms/cm up to 10 pico Ohms/cm;
applying the re-purified imaging oil to the amorphous silicon photoconductor prior to a charging portion of a subsequent print cycle to remove additional residue from the amorphous silicon photoconductor, thereby forming a further contaminated imaging oil; and
removing the further contaminated imaging oil from the amorphous silicon photoconductor.

### Claim 9 (depends on 8)

The method as defined in claim 8, further comprising repeating the purifying, the detecting, the applying, and the removing prior to the charging portion of each subsequent print cycle.

### Claim 10 (depends on 7)

The method as defined in claim 7 wherein:
the imaging oil filter is a mechanical filter of 2 micron particles; and
the polar absorbent filter is a silica gel filter or a carbon filter.

### Claim 11 (depends on 7)

The method as defined in claim 7 wherein after the removing, the method further comprises performing an other print cycle, wherein a print quality of a print formed during the other print cycle is maintained.

### Claim 12

A liquid electrophotographic printing apparatus, comprising:
an amorphous silicon photoconductor;
a cleaning station to periodically apply a purified imaging oil to the amorphous silicon photoconductor and to remove contaminated imaging oil from the amorphous silicon photoconductor; and
a recycling unit in fluid communication with the cleaning station, the recycling unit including:
a first compartment to receive the contaminated imaging oil from the cleaning station, the contaminated imaging oil including printing fluid particles and polar molecules;
an imaging oil filter to receive the contaminated imaging oil from the first compartment and to remove at least some of the printing fluid particles to form a filtered imaging oil;
a second compartment to receive the filtered imaging oil from the imaging oil filter; and
a polar absorbent filter to receive the filtered imaging oil from the second compartment and to remove the polar molecules to form the purified imaging oil.

### Claim 13 (depends on 12)

The liquid electrophotographic printing apparatus as defined in claim 12 wherein:
the imaging oil filter is a mechanical filter of 2 micron particles; and
the polar absorbent filter is a silica gel filter or a carbon filter.

### Claim 14 (depends on 12)

The liquid electrophotographic printing apparatus as defined in claim 12, further comprising a charging system, a fluid delivery system, and a fluid applicator.

### Claim 15 (depends on 12)

The liquid electrophotographic printing apparatus as defined in claim 12, further comprising:
a third compartment to receive the purified imaging oil from the polar absorbent filter; and
a conductivity meter position in the third compartment.