# US 2021/0341857 A1 · Print agent filtration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0341857 A1 - Document ID: US20210341857A1 - Status: Published application - Kind: A1 - Application number: 17/280,967 - Filed: 2018-11-29 - Published: 2021-11-04 - Earliest claimed: 2018-11-29 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Hewlett-Packard Development Company, L.P. - Inventors: Igor Chertov; Sergei Trifonov; Doron Schlumm - Web page: https://patentgrep.com/patent/US20210341857A1 ## CPC - G03G 15/104: {Preparing, mixing, transporting or dispensing developer} - B01D 33/06: with rotary cylindrical filtering surfaces, e.g. hollow drums (B01D33/044 takes precedence {; rotating drums for paper-making D21B}) - B01D 33/466: {scrapers} - B01D 35/06: Filters making use of electricity or magnetism (ultrafiltration, microfiltration B01D61/14; electrodialysis, electro-osmosis B01D61/42; devices comprising filters and magnetic separators B03C1/30) - B03C 5/026: {using open-gradient differential dielectric separation, i.e. using electrodes of special shapes for non-uniform field creation, e.g. Fluid Integrated Circuit [FIC]} - G03G 21/00: Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge - G03G 21/0005: {for removing solid developer or debris from the electrographic recording medium} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B03C: MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS (separating isotopes B01D59/00; combinations of magnetic or electrostatic separation with separation of solids by other means B03B, B07B) ## Abstract A print agent filtration apparatus is disclosed. The filtration apparatus is to remove non-liquid contaminant from liquid carrier. The apparatus comprises an electrode having a first surface, wherein the electrode is to generate an electric field towards liquid carrier containing non-liquid contaminant. The apparatus further comprises a second surface to accumulate non-liquid contaminant removed from the liquid carrier, the second surface being formed at least in part from a ceramic and movable relative to the first surface. A gap between the first surface and the second surface is substantially constant over the extent of the first surface. The first surface and the second surface define a passage therebetween through which the liquid carrier may pass. An electric field formed between the first surface and the second surface is to act on the liquid carrier, to thereby cause non-liquid contaminant to adhere to the second surface. A method and a print apparatus are also disclosed. ## Claims ### Claim 1 A print agent filtration apparatus to remove non-liquid contaminant from liquid carrier, the apparatus comprising: an electrode having a first surface, wherein the electrode is to generate an electric field towards liquid carrier containing non-liquid contaminant; and a second surface to accumulate non-liquid contaminant removed from the liquid carrier, the second surface being formed at least in part from a ceramic material and movable relative to the first surface; wherein a gap between the first surface and the second surface is substantially constant over the extent of the first surface; wherein the first surface and the second surface define a passage therebetween through which the liquid carrier may pass; and wherein an electric field formed between the first surface and the second surface is to act on the liquid carrier, to thereby cause non-liquid contaminant to adhere to the second surface. ### Claim 2 (depends on 1) A print agent filtration apparatus according to claim 1, further comprising: an inlet to receive the liquid carrier containing non-liquid contaminant; and an outlet to allow filtered liquid carrier to flow away from the apparatus. ### Claim 3 (depends on 2) A print agent filtration apparatus according to claim 2, wherein the inlet comprises multiple inlet apertures positioned at regular intervals along the length of the second surface. ### Claim 4 (depends on 2) A print agent filtration apparatus according to claim 2, wherein the outlet comprises multiple outlet apertures positioned at opposite ends of the second surface. ### Claim 5 (depends on 1) A print agent filtration apparatus according to claim 1, wherein the second surface comprises, or is formed on, a surface of a drum, the drum being rotatable relative to the first surface. ### Claim 6 (depends on 5) A print agent filtration apparatus according to claim 5, wherein the drum is to rotate at a rate of between around 0.2 revolutions per minute and around 0.5 revolutions per minute. ### Claim 7 (depends on 1) A print agent filtration apparatus according to claim 1, further comprising: a displacement element to displace non-liquid contaminant from the second surface. ### Claim 8 (depends on 7) A print agent filtration apparatus according to claim 7, wherein the displacement element comprises a blade; wherein the second surface is moveable relative to the blade, such that the blade is to displace non-liquid contaminant from the second surface as the second surface moves relative to the blade. ### Claim 9 A print agent filtration method to remove particles from liquid carrier, the method comprising: supplying liquid carrier through a passage defined by a surface of an electrode and a ceramic particle collection surface, a gap between the electrode surface and the particle collection surface being substantially constant over the extent of the electrode surface; applying a voltage to the electrode, thereby to generate an electric field between the electrode surface and the particle collection surface, and to cause particles from the liquid carrier to adhere to the particle collection surface. ### Claim 10 (depends on 9) A print agent filtration method according to claim 9, wherein the liquid carrier is supplied at a rate of between around 15 litres per minute and around 25 litres per minute. ### Claim 11 (depends on 9) A print agent filtration method according to claim 9, wherein the voltage suppled to the electrode comprises a voltage of between around 3.5 kV and around 4.5 kV. ### Claim 12 (depends on 9) A print agent filtration method according to claim 9, further comprising: positioning a displacement member in engagement with particles adhered to the particle collection surface; and moving the particle collection surface relative to the displacement member to displace adhered particles from the particle collection surface. ### Claim 13 (depends on 9) A print agent filtration method according to claim 9, further comprising: enabling filtered liquid carrier to egress the passage. ### Claim 14 A print apparatus comprising: a print component to print onto a printable substrate during a printing operation; and a filtration component to remove non-liquid contaminant from liquid carrier used in the printing operation, the filtration component comprising: an electrode having an electrode surface; a ceramic receiving surface to receive non-liquid contaminant removed from the liquid carrier, the receiving surface moveable relative to, and spaced apart from, the electrode surface to form a flow region through which the liquid carrier may pass; wherein, when an electric current is applied to the electrode, an electric field is formed between the electrode surface and the receiving surface, thereby causing non-liquid contaminant in the liquid carrier to adhere to the receiving surface. ### Claim 15 (depends on 14) A print apparatus according to claim 14, wherein the filtration component further comprises a displacement member to displace non-liquid contaminant from the receiving surface; and wherein the print apparatus further comprises: a reservoir to receive filtered liquid carrier from the flow region; and a receptacle to receive non-liquid contaminant displaced from the receiving surface.