# US 9,039,125 B2 · Multiple layer structures for void control in ink jet printers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,039,125 B2 - Document ID: US9039125B2 - Status: Granted - Kind: B2 - Application number: 13/714,365 - Filed: 2012-12-13 - Published: 2014-06-19 - Granted: 2015-05-26 - Earliest claimed: 2012-12-13 - Assignees: Palo Alto Research Center Incorporated - Applicants: Palo Alto Research Center Incorporated - Inventors: Eric J. Shrader - Web page: https://patentgrep.com/patent/US9039125B2 ## CPC - B41J 2/1408: {Structure dealing with thermal variations, e.g. cooling device, thermal coefficients of materials} - B41J 2/055: Devices for absorbing or preventing back-pressure - B41J 2/14201: {Structure of print heads with piezoelectric elements} - B41J 2/17593: {Supplying ink in a solid state} - B41J 2/19: for removing air bubbles - B41J 2002/14419: {Manifold} - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract Approaches to remove bubbles from ink in an ink jet printer are described. Bubble removal may be implemented using a membrane disposed along an ink flow path. The membrane includes first and second component membranes having first and second coefficients of thermal expansion. The membrane is configured to, in response to a change in ink temperature, mechanically displace as a function of temperature due to a difference in the thermal coefficients of expansion of the first and second component membranes. The mechanical displacement of the membrane causes a volumetric change in a portion of the ink flow path. ## Claims ### Claim 1 A subassembly for an inkjet printer for phase change ink comprising, a membrane disposed along an ink flow path, the membrane comprising first and second component membranes having first and second coefficients of thermal expansion, the membrane configured to, in response to temperature of the ink reaching an activation temperature, mechanically displace due to a difference in the thermal coefficients of expansion of the first and second component membranes, the activation temperature occurring during a time that the ink undergoes a phase change and transitions from liquid to solid or from solid to liquid, the mechanical displacement of the membrane causing a volumetric change in a portion of the ink flow path. ### Claim 2 (depends on 1) The subassembly of claim 1, wherein the membrane is a bimetallic membrane. ### Claim 3 (depends on 1) The subassembly of claim 1, wherein the membrane is configured to provide an abrupt mechanical displacement which causes an abrupt pressurization of ink in the portion of the ink flow path in response to the ink temperature reaching the activation temperature. ### Claim 4 (depends on 1) The subassembly of claim 1, wherein the activation temperature of the membrane corresponds to a mushy zone temperature of ink. ### Claim 5 (depends on 1) The subassembly of claim 1, wherein the activation temperature is about 80° C. ### Claim 6 (depends on 1) The subassembly of claim 1, wherein the membrane is configured to provide a gradual mechanical displacement which causes a gradual pressurization of ink in the portion of the ink flow path as a function of temperature. ### Claim 7 (depends on 1) The subassembly of claim 1, wherein the membrane is configured to provide a substantially linear mechanical displacement which causes a substantially linear pressurization of ink in the portion of the ink flow path as a function of temperature. ### Claim 8 (depends on 1) The subassembly of claim 1, further comprises one or more heaters configured to heat the ink and to impart a thermal gradient in the ink along the ink flow path, wherein a first and a second membrane have an activation temperature Tact and the thermal gradient causes the first membrane to mechanically displace before the second membrane mechanically displaces during a time that the ink is undergoing a phase change. ### Claim 9 (depends on 1) The subassembly of claim 1, wherein the membrane is disposed in a printhead of the subassembly. ### Claim 10 (depends on 1) The subassembly of claim 1, wherein the membrane is disposed in a reservoir of the subassembly. ### Claim 11 (depends on 1) The subassembly of claim 1, wherein the dual thermal coefficient membrane is disposed in a manifold of the subassembly. ### Claim 12 A method, comprising: heating or cooling ink in an ink flow path to cause a phase change of the ink; and causing a volumetric change in a portion of the ink flow path during the phase change, the volumetric change caused by mechanical displacement of a membrane as a function of temperature of the ink, the membrane comprising first and second component membranes having first and second thermal coefficients of expansion and the mechanical displacement is caused by differences in the first and second thermal coefficients of expansion, the mechanical displacement of the membrane responsive to the temperature of the ink reaching an activation temperature that occurs during a time that the ink is changing phase from solid to liquid or from liquid to solid. ### Claim 13 (depends on 12) The method of claim 12, wherein causing the volumetric change comprises pressurizing the ink in the ink flow path. ### Claim 14 (depends on 12) The method of claim 12, wherein causing the volumetric change comprises causing an abrupt mechanical displacement that occurs at an activation temperature. ### Claim 15 (depends on 12) The method of claim 12, wherein causing the volumetric change comprises causing a gradual mechanical displacement that occurs over a temperature range. ### Claim 16 (depends on 12) The method of claim 12, wherein causing the volumetric change comprises pressurizing the ink during a time that the ink is undergoing a phase change and ink in a first portion of the ink flow path is in a solid phase, ink in a second portion of the ink flow path is in a liquid phase, and ink in the portion of the ink flow path is at a mushy zone temperature range. ### Claim 17 (depends on 16) The method of claim 16, wherein the first portion comprises inkjet nozzles and the second portion comprises an ink reservoir. ### Claim 18 (depends on 16) The method of claim 16, wherein pressurizing the ink comprises forcing voids from ink in the portion of the ink flow path into the second portion.