# US 7,611,143 B2 · Sheet separating apparatus and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,611,143 B2 - Document ID: US7611143B2 - Status: Granted - Kind: B2 - Application number: 11/894,385 - Filed: 2007-08-21 - Published: 2009-02-26 - Granted: 2009-11-03 - Earliest claimed: 2007-08-21 - Assignees: Xerox Corporation - Inventors: Martin R. Walsh; Adrian Purnell - Web page: https://patentgrep.com/patent/US7611143B2 ## CPC - G03G 15/6511: {Feeding devices for picking up or separation of copy sheets} - B65H 5/062: {between rollers or balls} - B65H 7/02: by feelers or detectors - B65H 2511/514: Particular portion of element - B65H 2513/51: Sequence of process - B65H 2513/512: Starting; Stopping - B65H 2701/1311: leading edge - B65H 2701/1313: trailing edge - G03G 2215/00721: of sheet position - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - B65H: HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES ## Abstract A sheet separating mechanism and a method of separating sheets is provided to prevent the multifeeding of sheets into printers or copiers. The sheet separating mechanism provides a first nip and a second nip for feeding a series of sheets therebetween. The first nip can include a first motor and the second nip can include a second motor for feeding a leading sheet from the first nip to the second nip. The mechanism further provides a first sensor for sensing a trailing edge of the leading sheet and a second sensor for sensing a leading edge of the leading sheet. The first sensor is upstream of the first motor and the second sensor is downstream of the second motor. A trailing sheet can be prevented from feeding with the leading sheet by stopping the first motor when the leading edge of the leading sheet is sensed by the second sensor while simultaneously the first sensor remains occluded. ## Claims ### Claim 1 A sheet separating apparatus for a sheet feeder comprising: a first nip and a second nip for feeding a series of sheets therebetween; said first nip includes a first motor and said second nip includes a second motor for feeding a top sheet from said first nip to said second nip; a first sensor for sensing a trailing edge of said top sheet and a second sensor for sensing a leading edge of said top sheet wherein said first sensor is upstream of said first motor and said second sensor is downstream of said second motor; an underlying sheet is prevented from feeding with said top sheet by stopping said first motor when said leading edge of said top sheet is sensed by said second sensor while simultaneously said first sensor remains occluded by said underlying sheet; and, said first sensor and said second sensor have a fixed spacing therebetween wherein said spacing is greater than a sheet length. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein said top sheet has a predetermined length. ### Claim 3 A sheet separating apparatus for a sheet feeder comprising: a first nip and a second nip for feeding a series of sheets therebetween; said first nip includes a first motor and said second nip includes a second motor for feeding a top sheet from said first nip to said second nip; a first sensor for sensing a trailing edge of said top sheet and a second sensor for sensing a leading edge of said top sheet wherein said first sensor is upstream of said first motor and said second sensor is downstream of said second motor; an underlying sheet is prevented from feeding with said top sheet by stopping said first motor when said leading edge of said top sheet is sensed by said second sensor while simultaneously said first sensor remains occluded by said underlying sheet; said first sensor and said second sensor have a fixed spacing therebetween wherein said spacing is greater than a sheet length; wherein said top sheet has a predetermined length; and, a timer for timing the duration of time between entry of said leading edge and exit of said trailing edge of said top sheet with said second sensor. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein said duration is compared with a predetermined time based upon said predetermined sheet length; and, said underlying sheet becomes a next top sheet and said first motor feeds said underlying sheet from said first nip to said second nip when said duration is substantially equal to said predetermined time. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein said first nip and said second nip have a fixed spacing therebetween. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein a leading edge of said underlying sheet is stopped at a wait point when said first motor is stopped; and, said wait point is positioned between said first nip and said second nip. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein said wait point is upstream from said second motor. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein said underlying sheet has a leading edge; and, said leading edge of said top sheet is offset and downstream from said leading edge of said underlying sheet. ### Claim 9 A xerographic system, comprising: a sheet feeding apparatus having a first nip and an associated first sensor upstream from a second nip and an associated second sensor; said first sensor is upstream from said first nip and said second sensor is downstream from said second nip; said first nip includes a first motor and said second nip includes a second motor for selectively and independently feeding sheets therebetween; said first nip having a feed motion adapted to feed at least a pair of sheets in a feed direction from said first nip toward said second nip during said feed motion; said second nip having a feed motion adapted to feed a top sheet from said at least a pair of sheets in said feed direction; said first nip adapted to halt said feed motion responsive to said first and second sensors wherein an underlying sheet is stopped at a wait point positioned between said first nip and said second nip until said top sheet clears said second sensor; said first sensor and said second sensor have a fixed first spacing therebetween wherein said first spacing is greater than a sheet length; and, said first nip and said second nip have a fixed second spacing therebetween, wherein said first spacing is greater than said second spacing. ### Claim 10 (depends on 9) The system of claim 9, wherein said pair of sheets each have a predetermined length. ### Claim 11 (depends on 10) The system of claim 10, further including a timer for timing the duration of time between entry of a leading edge and exit of a trailing edge of said top sheet with said second sensor. ### Claim 12 (depends on 11) The system of claim 11, wherein said duration is compared with a predetermined time based upon said predetermined sheet length; and, said underlying sheet becomes a next top sheet and a first motor feeds said underlying sheet from said first nip to said second nip when said duration is substantially equal to said predetermined time. ### Claim 13 (depends on 9) The system of claim 9, wherein a leading edge of said underlying sheet is stopped at said wait point when said first motor is stopped. ### Claim 14 (depends on 13) The system of claim 13, wherein said leading edge of said top sheet is offset and downstream from said leading edge of said underlying sheet. ### Claim 15 A method of feeding sheets to a printer or a copier, comprising: applying a feed force in a feed direction to a top sheet; feeding said top sheet from a first nip to a second nip wherein said first nip includes a first motor and said second nip includes a second motor; sensing a trailing edge of said top sheet with a first sensor and sensing a leading edge of said top sheet with a second sensor wherein said first sensor is upstream of said first motor and said second sensor is downstream of said second motor; preventing an underlying sheet from feeding with said top sheet by stopping said first motor while continuing said second motor, when said leading edge of said top sheet is sensed by said second sensor while simultaneously said first sensor remains occluded by said underlying sheet; and, said first sensor and said second sensor have a fixed spacing therebetween wherein said spacing is greater than a sheet length. ### Claim 16 (depends on 15) The method of claim 15, wherein said top sheet has a predetermined length. ### Claim 17 (depends on 16) The method of claim 16, wherein said first nip and said second nip have a fixed spacing therebetween. ### Claim 18 (depends on 17) The method of claim 17, wherein said underlying sheet has a leading edge; and, said leading edge of said top sheet is offset and downstream from said leading edge of said underlying sheet. ### Claim 19 A method of feeding sheets to a printer or a copier, comprising: applying a feed force in a feed direction to a top sheet; feeding said top sheet from a first nip to a second nip wherein said first nip includes a first motor and said second nip includes a second motor; sensing a trailing edge of said top sheet with a first sensor and sensing a leading edge of said top sheet with a second sensor wherein said first sensor is upstream of said first motor and said second sensor is downstream of said second motor; preventing an underlying sheet from feeding with said top sheet by stopping said first motor while continuing said second motor, when said leading edge of said top sheet is sensed by said second sensor while simultaneously said first sensor remains occluded by said underlying sheet; said first sensor and said second sensor have a fixed spacing therebetween wherein said spacing is greater than a sheet length; wherein said top sheet has a predetermined length; wherein said first nip and said second nip have a fixed spacing therebetween: wherein said underlying sheet has a leading edge; wherein said leading edge of said top sheet is offset and downstream from said leading edge of said underlying sheet; comparing a time between sensing said leading edge and said trailing edge of said top sheet by said second sensor with a predetermined time, if said time is substantially equal to said predetermined time, then said underlying sheet becomes the next top sheet; and, feeding said next top sheet from said first nip to said second nip. ### Claim 20 A xerographic system, comprising: a sheet feeding apparatus having a first nip and an associated first sensor upstream from a second nip and an associated second sensor; said first sensor is upstream from said first nip and said second sensor is downstream from said second nip; said first nip includes a first motor and said second nip includes a second motor for selectively and independently feeding sheets therebetween; said first nip having a feed motion adapted to feed at least a pair of sheets in a feed direction from said first nip toward said second nip during said feed motion; said second nip having a feed motion adapted to feed a top sheet from said at least a pair of sheets in said feed direction; said first nip adapted to halt said feed motion responsive to said first and second sensors wherein an underlying sheet is stopped at a wait point positioned between said first nip and said second nip until said top sheet clears said second sensor; said underlying sheet is prevented from feeding with said top sheet by stopping said first motor, while continuing said second motor, when said leading edge of said top sheet is sensed by said second sensor while simultaneously said first sensor remains occluded by said underlying sheet; and, said first sensor and said second sensor have a fixed first spacing therebetween wherein said first spacing is greater than a sheet length. ### Claim 21 (depends on 20) The system of claim 20, wherein said first nip and said second nip have a fixed second spacing therebetween; and, said first spacing is greater than said second spacing.