# US 2026/0091584 A1 · Liquid ejection head > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2026/0091584 A1 - Document ID: US20260091584A1 - Status: Published application - Kind: A1 - Application number: 19/280,078 - Filed: 2025-07-24 - Published: 2026-04-02 - Earliest claimed: 2024-09-30 - Assignees: RISO Technologies Corporation - Applicants: RISO Technologies Corporation - Inventors: Noboru NITTA; Masahiro KODO; Shinichiro HIDA - Web page: https://patentgrep.com/patent/US20260091584A1 ## CPC - B41J 2/14: Structure thereof {only for on-demand ink jet heads} - B41J 2/14274: {of stacked structure type, deformed by compression/extension and disposed on a diaphragm} - B41J 2/175: Ink supply systems {; Circuit parts therefor} - B41J 2002/14419: {Manifold} - B41J 2202/11: characterised by specific geometrical characteristics - B41J 2202/12: with ink circulating through the whole print head - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract A liquid ejection head includes pressure chambers arranged in a first direction and respectively communicating with nozzles, pairs of upstream and downstream flow paths extending in a second direction different from the first direction, each pair communicating with a pressure chamber, the upstream path connected to a first end of the corresponding chamber, and the downstream path of said each pair connected to a second end of the chamber, an upstream common chamber communicating with the upstream paths, a downstream common chamber communicating with the downstream paths, and a bypass flow path communicating with the upstream chamber at an end thereof and the downstream chamber at an end thereof. Each upstream path has an inlet connected to the upstream chamber and an outlet connected to the corresponding chamber, the inlet widening toward the end of the upstream chamber. ## Claims ### Claim 1 A liquid ejection head comprising: a plurality of pressure chambers arranged in a first direction and respectively communicating with nozzles, each pressure chamber capable of storing liquid; a plurality of pairs of upstream and downstream flow paths extending in a second direction different from the first direction, each pair communicating with a corresponding one of the pressure chambers, the upstream flow path of each pair being connected to a first end of the corresponding pressure chamber, and the downstream flow path of said each pair being connected to a second end of the corresponding pressure chamber; an upstream common chamber communicating with the upstream flow paths; an upstream port communicating with the upstream common chamber at a first end of the upstream common chamber in the first direction; a downstream common chamber communicating with the downstream flow paths; a downstream port communicating with the downstream common chamber; and a bypass flow path communicating with the upstream common chamber at a second end of the upstream common chamber in the first direction and with the downstream common chamber, wherein each of the upstream flow paths has an inlet that is connected to the upstream common chamber and an outlet that is connected to the corresponding pressure chamber, the inlet widening toward the second end of the upstream common chamber. ### Claim 2 (depends on 1) The liquid ejection head according to claim 1, wherein the inlet has a surface that is inclined with respect to the second direction when viewed from a third direction perpendicular to the first and second directions. ### Claim 3 (depends on 2) The liquid ejection head according to claim 2, wherein the inclined surface forms an angle of 45 degrees with the first direction when viewed from the third direction. ### Claim 4 (depends on 1) The liquid ejection head according to claim 1, wherein each of the downstream flow paths has an inlet that is connected to the corresponding pressure chamber and an outlet that is connected to the downstream common chamber, the outlet widening toward an end of the downstream common chamber. ### Claim 5 (depends on 4) The liquid ejection head according to claim 4, wherein the outlet has a surface that is inclined with respect to the second direction when viewed from a third direction perpendicular to the first and second directions. ### Claim 6 (depends on 5) The liquid ejection head according to claim 5, wherein the inclined surface forms an angle of 45 degrees with the second direction when viewed from the third direction. ### Claim 7 (depends on 1) The liquid ejection head according to claim 1, wherein each of the nozzles is disposed at a location between the first and second ends of the corresponding pressure chamber. ### Claim 8 A liquid ejection head comprising: a plurality of pressure chambers arranged in a first direction and respectively communicating with nozzles, each pressure chamber capable of storing liquid; a plurality of pairs of upstream and downstream flow paths, each pair communicating with a corresponding one of the pressure chambers, the upstream flow path of each pair being connected to a first end of the corresponding pressure chamber, and the downstream flow path of said each pair being connected to a second end of the corresponding pressure chamber; an upstream common chamber communicating with the upstream flow paths; an upstream port communicating with the upstream common chamber at a first end of the upstream common chamber in the first direction; a downstream common chamber communicating with the downstream flow paths; a downstream port communicating with the downstream common chamber; and a bypass flow path communicating with the upstream common chamber at a second end of the upstream common chamber in the first direction and with the downstream common chamber, wherein a circulation flow rate of the liquid is greater than or equal to a maximum total ejection flow rate of the liquid ejected from the nozzles, the circulation flow rate is a flow rate at which the liquid flowing through the upstream flow paths to the downstream flow paths when a flow rate of the liquid entering from the upstream port is substantially equal to a flow rate of the liquid exiting through the downstream port, and the maximum total ejection flow rate is a flow rate at a full duty with all nozzles ejecting. ### Claim 9 (depends on 8) The liquid ejection head according to claim 8, wherein a flow path resistance of the bypass flow path is less than or equal to a parallel flow path resistance of flow paths extending from inlets of the upstream flow paths to outlets of the downstream flow paths. ### Claim 10 (depends on 8) The liquid ejection head according to claim 8, wherein in a direction of a circulating flow of the liquid, a cross section of each of the upstream and downstream flow paths is smaller than a cross section of the corresponding pressure chamber. ### Claim 11 (depends on 8) The liquid ejection head according to claim 8, wherein in a direction of a bypass circulating flow of the liquid, a cross section of the upstream common chamber is larger than a cross section of the bypass flow path. ### Claim 12 (depends on 8) The liquid ejection head according to claim 8, wherein each of the nozzles is disposed at a location between the first and second ends of the corresponding pressure chamber. ### Claim 13 (depends on 8) The liquid ejection head according to claim 8, wherein the upstream and downstream flow paths extend in a second direction different from the first direction, each of the upstream flow paths has an inlet that is connected to the upstream common chamber and an outlet that is connected to the corresponding pressure chamber, and the inlet of one of the upstream flow paths has a surface that is inclined with respect to the second direction when viewed from a third direction perpendicular to the first and second directions. ### Claim 14 (depends on 13) The liquid ejection head according to claim 13, wherein the inclined surface forms an angle of 45 degrees with the second direction when viewed from the third direction. ### Claim 15 (depends on 8) The liquid ejection head according to claim 8, wherein the circulation flow rate through the pressure chamber is less than the maximum total ejection flow rate. ### Claim 16 A liquid ejection head, comprising: a plurality of pressure chambers arranged in a first direction and respectively communicating with nozzles, each pressure chamber capable of storing liquid; a plurality of pairs of upstream and downstream flow paths, each pair communicating with a corresponding one of the pressure chambers, the upstream flow path of each pair being connected to a first end of the corresponding pressure chamber, and the downstream flow path of said each pair being connected to a second end of the corresponding pressure chamber; an upstream common chamber communicating with the upstream flow paths; an upstream port communicating with the upstream common chamber at a first end of the upstream common chamber in the first direction; a downstream common chamber communicating with the downstream flow paths; a downstream port communicating with the downstream common chamber; a bypass flow path communicating with the upstream common chamber at a second end of the upstream common chamber in the first direction and with the downstream common chamber; and a pressure damper provided in the bypass flow path. ### Claim 17 (depends on 16) The liquid ejection head according to claim 16, wherein the pressure damper is a membrane damper formed of a flexible resin. ### Claim 18 (depends on 17) The liquid ejection head according to claim 17, wherein the pressure damper forms a surface of the bypass flow path. ### Claim 19 (depends on 16) The liquid ejection head according to claim 16, wherein each of the nozzles is disposed at a location between the first and second ends of the corresponding pressure chamber. ### Claim 20 (depends on 16) The liquid ejection head according to claim 16, wherein the upstream and downstream flow paths extend in a second direction different from the first direction, each of the upstream flow paths has an inlet that is connected to the upstream common chamber and an outlet that is connected to the corresponding pressure chamber, and the inlet of one of the upstream flow paths has a surface that is inclined with respect to the second direction when viewed from a third direction perpendicular to the first and second directions.