# US 2017/0255155 A1 · Sheet stacker, image forming apparatus, and sheet conveyance control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0255155 A1 - Document ID: US20170255155A1 - Status: Published application - Kind: A1 - Application number: 15/428,697 - Filed: 2017-02-09 - Published: 2017-09-07 - Earliest claimed: 2016-03-04 - Assignees: Ricoh Company, Ltd. - Inventors: Tadayasu ENOMOTO; Ryo TAKENAKA; Daikai ZAITSU - Web page: https://patentgrep.com/patent/US20170255155A1 ## CPC - G03G 15/6552: {Means for discharging uncollated sheet copy material, e.g. discharging rollers, exit trays} - B65H 85/00: Recirculating articles, i.e. feeding each article to, and delivering it from, the same machine work-station more than once - G03G 15/234: {by inverting and refeeding the image receiving material with an image on one face to the recording member to transfer a second image on its second face, e.g. by using a duplex tray; Details of duplex trays or inverters} - G03G 15/6573: {Feeding path after the fixing point and up to the discharge tray or the finisher, e.g. special treatment of copy material to compensate for effects from the fixing} - B65H 2402/60: Coupling, adapter or locking means - B65H 2404/61: Longitudinally-extending strips, tubes, plates, or wires - B65H 2404/691: Guiding means extensible in material transport direction - B65H 2405/31: Supports for sheets fully removable from the handling machine, e.g. cassette - B65H 2801/06: Office-type machines, e.g. photocopiers - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - B65H: HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES ## Abstract A sheet stacker includes a sheet stack table on which a sheet is stacked and a sheet reversing section disposed above the sheet stack table. The sheet reversing section defines a sheet reverse passage to reverse a direction of conveyance of a sheet fed to the sheet reversing section. The sheet reversing section includes a first sheet guide to guide a bottom face of the sheet and a second sheet guide disposed downstream from the first sheet guide in a sheet conveyance direction in which the sheet is fed to the sheet reversing section. The second sheet guide to guide the bottom face of the sheet is attachable to and removable from an apparatus body. ## Claims ### Claim 1 A sheet stacker comprising: a sheet stack table on which a sheet is stacked; and a sheet reversing section disposed above the sheet stack table, the sheet reversing section defining a sheet reverse passage to reverse a direction of conveyance of a sheet fed to the sheet reversing section, the sheet reversing section including: a first sheet guide to guide a bottom face of the sheet; and a second sheet guide disposed downstream from the first sheet guide in a sheet conveyance direction in which the sheet is fed to the sheet reversing section, the second sheet guide attachable to and removable from an apparatus body, the second sheet guide to guide the bottom face of the sheet. ### Claim 2 (depends on 1) The sheet stacker according to claim 1, wherein the sheet reversing section further includes: a first guide cover to cover the first sheet guide; and a second guide cover attachable to and removable from the apparatus body, the second guide cover to cover the second sheet guide. ### Claim 3 (depends on 1) The sheet stacker according to claim 1, wherein a sheet-opposing face of at least one of the first sheet guide and the second sheet guide to oppose the sheet has a ragged shape. ### Claim 4 (depends on 3) The sheet stacker according to claim 3, wherein the at least one of the first sheet guide and the second sheet guide includes a plurality of ribs each extending in the sheet conveyance direction and projecting from the sheet-opposing face, the plurality of ribs arranged in a sheet width direction perpendicular to the sheet conveyance direction to form the ragged shape. ### Claim 5 (depends on 1) The sheet stacker according to claim 1, wherein the second sheet guide includes a coupling portion to be coupled with a coupled portion of the apparatus body, wherein one of the coupling portion and the coupled portion has an insertion hole, and wherein the other of the coupling portion and the coupled portion has a hooked shape. ### Claim 6 (depends on 5) The sheet stacker according to claim 5, wherein the second sheet guide further includes an opposite-side coupling portion disposed opposite the coupling portion in a sheet width direction perpendicular to the sheet conveyance direction, the opposite-side coupling portion to engage an opposite-side coupled portion of the apparatus body. ### Claim 7 (depends on 6) The sheet stacker according to claim 6, wherein the opposite-side coupled portion of the apparatus body has an insertion hole, and wherein the opposite-side coupling portion is to move into and away from the opposite-side coupled portion. ### Claim 8 (depends on 7) The sheet stacker according to claim 7, wherein the opposite-side coupling portion is to fit in the opposite-side coupled portion to determine a position of the opposite-side coupling portion relative to the apparatus body. ### Claim 9 (depends on 1) The sheet stacker according to claim 1,further comprising an ancillary guide to move between a first position contained inside the first sheet guide and a second position downstream in the sheet conveyance direction from a downstream end of the first sheet guide, wherein the ancillary guide guides the bottom face of the sheet at the second position. ### Claim 10 (depends on 9) The sheet stacker according to claim 9, the second sheet guide is attachable to and removable from the apparatus body when the ancillary guide is at the first position. ### Claim 11 (depends on 9) The sheet stacker according to claim 9, wherein a sheet-opposing face of the ancillary guide to oppose the sheet has a ragged shape. ### Claim 12 (depends on 1) The sheet stacker according to claim 1, wherein the sheet reversing section further includes: a guide cover hinged to open and close relative to the first sheet guide, the guide cover to cover the first sheet guide; and a guide cover sensor to detect whether the guide cover is open relative to the first sheet guide. ### Claim 13 (depends on 12) The sheet stacker according to claim 12, wherein, in an operation involving sheet feeding to the sheet reversing section, the guide cover sensor detects whether the guide cover is open, and wherein a sheet conveying operation is inhibited when the guide cover sensor detects the guide cover being open. ### Claim 14 (depends on 12) The sheet stacker according to claim 12, wherein, in an operation in which the sheet is not fed to the sheet reversing section, a sheet conveying operation is executed regardless of whether the guide cover is open. ### Claim 15 An image forming apparatus comprising: an image forming device to form an image on a sheet; a sheet stack table on which the sheet is stacked after an image is formed on the sheet; a sheet reversing section disposed above the sheet stack table, the sheet reversing section defining a sheet reverse passage to reverse a direction of conveyance of a sheet fed to the sheet reversing section, the sheet reversing section including: a first sheet guide to guide a bottom face of the sheet, and a second sheet guide disposed downstream from the first sheet guide in a sheet conveyance direction in which the sheet is fed to the sheet reversing section, the second sheet guide attachable to and removable from an apparatus body, the second sheet guide to guide the bottom face of the sheet. ### Claim 16 A sheet conveyance control method comprising: determining whether a job involves sheet feeding to a sheet reverse passage; detecting whether a guide cover to cover a sheet reverse passage is open when the job involves the sheet feeding to the sheet reverse passage; and inhibiting a sheet conveying operation when the guide cover being open is detected. ### Claim 17 (depends on 16) The method according to claim 16, wherein, when the job is free of the sheet feeding to the sheet reverse passage, a sheet conveying operation is executed regardless of whether the guide cover is open.