# US 5,264,899 A · Sheet moisture replacement system using porous rolls > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,264,899 A - Document ID: US5264899A - Status: Granted - Kind: A - Application number: 07/963,963 - Filed: 1992-10-21 - Granted: 1993-11-23 - Earliest claimed: 1992-10-21 - Assignees: Xerox Corporation - Inventors: Barry P. Mandel - Web page: https://patentgrep.com/patent/US5264899A ## CPC - 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} - G03G 15/2064: {combined with pressure} - G03G 2215/00421: Discharging tray, e.g. devices stabilising the quality of the copy medium, postfixing-treatment, inverting, sorting - G03G 2215/0067: Damping device - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A system for adding moisture to a copy sheet is disclosed. The toner fixation step of electrostatographic reproduction desiccates paper, which may lead to the formation a wave along the sheet edge. The invention uses a pair of porous rolls defining a nip to transfer additional moisture to the copy sheet as it is passed through the nip. The added moisture prevents edge wave formation. ## Claims ### Claim 1 A device for adding moisture to a copy sheet, comprising: a reservoir for storing a quantity of liquid; a pair of generally cylindrical rolls, each having an outer cylindrical surface, said rolls being aligned with respect to one another along their axes so as to define a nip between said outer cylindrical surfaces, and at least one of said rolls i) having a hollow shaft for support thereon and rotation therewith, said shaft further having channels therein for accommodating the passage of liquid to the roll and further including bearing means for rotation thereabout; and ii) being constructed of a material having a microporous structure enabling liquid to flow from the center of the roll to its periphery; conduit means for conducting fluid from the reservoir to at least one of said rolls; flow control means intermediate the rolls and the reservoir for controlling the flow of fluid along said conduit means from the reservoir to at least one of said rolls; and means for rotating at least one of said rolls about its central cylindrical axis, wherein liquid is conducted along the conduit means from the reservoir to the hollow shaft of at least one roll, and from thence through the micropores of the roll to its outer cylindrical surface for transfer to a copy sheet as it passes through the nip. ### Claim 2 (depends on 1) The device of claim 1, wherein at least one of the rolls has a plurality of narrow grooves along its outer cylindrical surface. ### Claim 3 (depends on 2) The device of claim 2, further comprising exit baffles for transporting a copy sheet away from the nip defined by the rolls, and the exit baffles include stripper fingers configured to cooperate with the grooves in the roll so as to prevent the copy sheet from adhering to the rolls. ### Claim 4 (depends on 1) The device of claim 1, further comprising lead in baffles for transporting a copy sheet to the nip defined by the rolls. ### Claim 5 (depends on 4) The device of claim 4, wherein the rolls are rotated at a rate at which their outer cylindrical surfaces match the velocity of a sheet of paper being transported along said lead in baffles to said rolls. ### Claim 6 (depends on 1) The device of claim 1, wherein the reservoir contains water. ### Claim 7 (depends on 6) The device of claim 6 wherein the water contains a wetting agent. ### Claim 8 (depends on 1) The device of claim 1, wherein the flow control means include a pump and a valve. ### Claim 9 (depends on 8) The device of claim 8, wherein the flow control means further include a microprocessor for controlling the flow of liquid. ### Claim 10 (depends on 1) The device of claim 1, further comprising a catch basin for collecting excess liquid that drops from the rolls. ### Claim 11 A system for fixing a toner image to a copy sheet in an electrostatographic system so as to avoid the formation of a wave along the edge of the copy sheet, comprising: first and second fusing rollers defining a nip therebetween, at least one of said fusing rollers being heated, wherein the fusing rollers serve to fix a toner image on a copy sheet through the application of heat and pressure to the copy sheet; means for conveying the copy sheet from the fusing rollers to a moisture replenishing station, said moisture replenishing station including i) a reservoir for storing a quantity of liquid; ii) a pair of generally cylindrical porous rolls arranged so as to define a nip therebetween; and iii) means for conveying liquid from the reservoir to the porous rolls at a measured rate, wherein the copy sheet is supplied with liquid from the porous rolls as it passes through the nip defined by the porous rolls. ### Claim 12 (depends on 11) The device of claim 11, wherein at least one of the porous rolls has a plurality of narrow grooves along its outer cylindrical surface. ### Claim 13 (depends on 11) The device of claim 11, further comprising lead in baffles for transporting a copy sheet to the nip defined by the porous rolls. ### Claim 14 (depends on 13) The device of claim 13, wherein the porous rolls are rotated at a rate at which their outer cylindrical surfaces match the velocity of a sheet of paper being transported along said lead in baffles to said porous rolls. ### Claim 15 (depends on 11) The device of claim 11, wherein the reservoir contains water. ### Claim 16 (depends on 15) The device of claim 15 wherein the water contains a wetting agent. ### Claim 17 (depends on 11) The device of claim 11, further comprising exit baffles for transporting a copy sheet away from the nip defined by the porous rolls, and the exit baffles include stripper fingers configured to cooperate with grooves in at least one of the porous rolls so as to prevent the copy sheet from adhering to the porous rolls. ### Claim 18 (depends on 11) The device of claim 11, wherein the flow control means include a pump and a valve. ### Claim 19 (depends on 18) The device of claim 18, wherein the flow control means further include a microprocessor for controlling the flow of liquid. ### Claim 20 (depends on 11) The device of claim 11, further comprising a catch basin for collecting excess liquid that drops from the rolls. ### Claim 21 A method for replenishing the moisture that a copy sheet loses as it is heated in an electrostatographic machine of the type having a thermal fuser, comprising the steps of: transporting liquid from a reservoir to a pair of rolls made of a microporous material that are arranged so as to form a nip therebetween; transporting the copy sheet from the fuser through the nip of the rolls; and transferring liquid from the rolls to said copy sheet. ### Claim 22 (depends on 21) The method of claim 21, wherein the liquid contains a wetting agent for facilitating the even transfer of said liquid to the copy sheet. ### Claim 23 (depends on 21) The method of claim 21, wherein the rate at which the liquid is conveyed from the reservoir to the rolls is dependant upon the copy sheet feed rate and the ambient humidity. ### Claim 24 (depends on 23) The method of claim 23, wherein the conveyance of liquid to the rolls is governed by a microprocessor to which is supplied information from sensor means.