# US 5,875,033 A · Sheet size detecting apparatus responsive to a conveying speed of the sheet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,875,033 A - Document ID: US5875033A - Status: Granted - Kind: A - Application number: 08/535,664 - Filed: 1995-09-28 - Granted: 1999-02-23 - Earliest claimed: 1994-09-30 - Assignees: Canon Kabushiki Kaisha - Inventors: Wataru Kawata; Akimaro Yoshida - Web page: https://patentgrep.com/patent/US5875033A ## CPC - G03G 15/607: {for detecting size, presence or position of original} - H04N 1/00681: {Detecting the presence, position or size of a sheet or correcting its position before scanning (H04N1/047 takes precedence; mode signalling H04N1/333; skew detection or correction in image signals H04N1/3878)} - H04N 1/00713: {Length} - H04N 1/00732: {Mechanical detectors} - H04N 1/00745: {Detecting the leading or trailing ends of a moving sheet} - G03G 2215/00333: detecting feeding of documents - H04N 1/12: using the sheet-feed movement {or the medium-advance or the drum-rotation movement} as the slow scanning component, {e.g. arrangements for the main-scanning}({sheet-feed movement by translatory movement of a flat picture-bearing surface H04N1/1008; main-scanning using oscillating or rotating mirrors H04N1/113; } using multi-element arrays H04N1/19) - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A sheet size detecting apparatus includes a rotary member for conveying a sheet rotation detector together with the rotary member for generating a pulse, a sheet size measurement control device including an arm provided in a vicinity of the rotary member to effect reciprocally rocking by the passing of the front end and the rear end of the sheet. The sheet size measurement control device measures the size of the sheet by counting pulses generated by the rotation detector means in response to the rocking of the arm and, adds a correction value to the measured sheet size according to the conveying speed of the sheet. ## Claims ### Claim 1 A sheet size detecting apparatus comprising: a rotary member for conveying a sheet; rotation detecting means rotating together with said rotary member for generating pulses; arm means provided proximate to said rotary member to effect reciprocal rocking by passing of the front end and the rear end of the sheet; and control means for measuring an apparent size of the sheet by counting the pulses generated by said rotation detecting means in response to the rocking of said arm means, and adding a correcting rectified value to a measured apparent size according to a conveying speed of the sheet to get an actual size of the sheet. ### Claim 2 (depends on 1) A sheet size detecting apparatus according to claim 1, wherein said rotation detecting means includes a rotary plate having slits thereon and an encoder for counting the number of slits, and said control means measures a size of the sheet from the peripheral length of said rotary member and the measured number of the slits. ### Claim 3 (depends on 1) A sheet size detecting apparatus according to claim 1, wherein said control means includes switch means to be turned on and off respectively by a forward motion and a reverse motion of said arm means, and a number of pulses is counted within a period from turning-on to turning-off of said switch means. ### Claim 4 (depends on 3) A sheet size detecting apparatus according to claim 3, wherein said control means corrects a measured number of pulses, based on a correction value determined in advance according to the conveying speed of the sheet. ### Claim 5 (depends on 3) A sheet size detecting apparatus according to claim 3 if the rear end of the sheet passes said rotary member simultaneously with the turning-off of the switch means caused by release of the arm means from the rear end of the sheet, no rectification is added. ### Claim 6 (depends on 5) A sheet size detecting apparatus according to claim 5, wherein, if said switch means is not turned off even after the rear end of the sheet passes said rotary member, the number of pulses counted thereafter until the turning-off of said switch means is an error, and the number of pulses is measured in advance in correspondence with the conveying speed of the sheet. ### Claim 7 (depends on 6) A sheet size detecting apparatus according to claim 6, wherein said control means measures the size of the sheet by adding a correcting rectification for subtraction of the number of pulses of the error from the actually measured number of pulses. ### Claim 8 (depends on 7) A sheet size detecting apparatus according to claim 7, wherein said rotary member conveys the sheet by plural predetermined speeds, among which one speed is selected according to a mode. ### Claim 9 (depends on 8) A sheet size detecting apparatus according to claim 8, wherein said rotary member stops, after conveying the sheet by a small amount, and then conveys the sheet again. ### Claim 10 (depends on 7) A sheet size detecting apparatus according to claim 7, wherein said control means measures the actual sheet size and determines a kind of the sheet by comparison with size data of various sheets stored in advance. ### Claim 11 (depends on 10) A sheet size detecting apparatus according to claim 10, wherein the kind of sheet is a rated size such as A4, B5, and the like. ### Claim 12 (depends on 7) A sheet size detecting apparatus according to claim 7, wherein said rotation detecting means includes a rotary plate having slits thereon and an encoder for counting the number of slits, and said control means measures a size of the sheet from the peripheral length of said rotary member and the measured number of the slits. ### Claim 13 (depends on 1) A sheet size detecting apparatus according to claim 1, wherein said control means measures the actual sheet size by judgment of size data, and determines a kind of the sheet by comparison with size data of various sheets stored in advance. ### Claim 14 (depends on 1) A sheet size detecting apparatus according to claim 1, wherein said rotary member conveys the sheet by plural predetermined speeds, among which one speed is selected according to a mode. ### Claim 15 (depends on 14) A sheet size detecting apparatus according to claim 14, wherein said rotary member stops, after conveying the sheet by a small amount, and then conveys the sheet again. ### Claim 16 A sheet size detecting apparatus comprising: a rotary member for conveying a sheet; a pulse generating means rotating together with and synchronous with said rotary member for generating pulses; an arm means provided proximate to said rotary member to effect a reciprocal rocking by passing of the front end and the rear end of the sheet; and control means for measuring an apparent size of the sheet by counting pulses generated by a pulse generating means in response to the rocking of said arm means, and adding a correcting rectification to a measured apparent size according to a conveying speed of the sheet to get an actual size of the sheet, wherein said control means includes a switching means to be turned on and off respectively by a forward motion and a reverse motion of said arm means, and a number of pulses is counted within a period from the turn-on to turn-off of said switch means. ### Claim 17 (depends on 16) A sheet size detecting apparatus according to claim 16, wherein said control means corrects a measured number of pulses, based on a correction value determined in advance according to the conveying speed of the sheet. ### Claim 18 (depends on 16) A sheet size detecting apparatus according to claim 16, wherein, if the rear end of the sheet passes said rotary member simultaneously with the turning-off of the switch means caused by release of the arm means from the rear end of the sheet, no rectification is added. ### Claim 19 (depends on 18) A sheet size detecting apparatus according to claim 18, wherein if said switch means is not turned off even after the rear end of the sheet passes said rotary member, the number of the pulses counted thereafter until the turning-off of said switch means is an error number, and the number of pulses is measured in advance in correspondence with the conveying speed of the sheet. ### Claim 20 (depends on 19) A sheet size detecting apparatus according to claim 19, wherein said control means measures the size of the sheet by subtraction of the number of pulses corresponding to the error from the actually measured number of pulses. ### Claim 21 An automatic original feeding apparatus having sheet size detecting apparatus comprising: a rotary member for conveying a sheet; rotation detecting means rotating together with said rotary member for generating pulses; arm means provided proximate to said rotary member to effect reciprocal rocking by passing of the front end and the rear end of the sheet; and control means for measuring an apparent size of the sheet by counting the pulses generated by said rotation detecting means in response to the rocking of said arm means, and adding a correcting rectification to a measured apparent size according to a conveying speed of the sheet to get an actual size of the sheet. ### Claim 22 (depends on 21) An automatic original feeding apparatus according to claim 21, wherein said rotation detecting means includes a rotary plate having slits thereon and an encoder for counting the number of slits, and said control means measures a size of the sheet from the peripheral length of said rotary member and the measured number of the slits. ### Claim 23 (depends on 21) An automatic original feeding apparatus according to claim 21, wherein said control means includes switch means to be turned on and off respectively by a forward motion and a reverse motion of said arm means, and a number of pulses is counted within a period from turning-on to turning-off said switch means. ### Claim 24 (depends on 23) An automatic original feeding apparatus according to claim 23, wherein said control means corrects a measured number of pulses, based on a correction value determined in advance according to the conveying speed of the sheet. ### Claim 25 (depends on 23) An automatic original feeding apparatus according to claim 23, wherein, if the rear end of the sheet passes said rotary member simultaneously with the turning-off of the switch means caused by release of the arm means from the rear end of the sheet, no correcting rectification is added. ### Claim 26 (depends on 25) An automatic original feeding apparatus according to claim 25, wherein if said switch means is not turned off even after the rear end of the sheet passes said rotary member, the number of pulses counted thereafter until the turning-off of said switch means is an error number, and the number of pulses is measured in advance in correspondence with the conveying speed of the sheet. ### Claim 27 (depends on 26) An automatic original feeding apparatus according to claim 26, wherein said control means measures the size of the sheet by subtraction of the number of pulses corresponding to the error number from the actually measured number of pulses. ### Claim 28 (depends on 27) An automatic original feeding apparatus according to claim 27, wherein said rotary member conveys the sheet by plural predetermined speeds, among which one speed is selected according to a mode. ### Claim 29 (depends on 38) An automatic original feeding apparatus according to claim 38, wherein said rotary member stops, after conveying the sheet by a small amount, and then conveys the sheet again. ### Claim 30 (depends on 27) An automatic original feeding apparatus according to claim 27, wherein said control means measures the actual sheet size and determines kind of the sheet by comparison with size data of various sheets stored in advance. ### Claim 31 (depends on 30) An automatic original feeding apparatus according to claim 30, wherein the kind of sheet is a rated size such as A4, B5, and the like. ### Claim 32 (depends on 27) An automatic original feeding apparatus according to claim 27, wherein said rotation detecting means includes a rotary plate having slits thereon and an encoder for counting the number of slits, and said control means measures a size of the sheet form the peripheral length of said rotary member and the measured number of the slits. ### Claim 33 (depends on 21) An automatic original feeding apparatus according to claim 21, wherein said control means measures the actual sheet size and determines a kind of the sheet by comparison with size data of various sheets stored in advance. ### Claim 34 (depends on 21) An automatic original feeding apparatus according to claim 21, wherein said rotary member conveys the sheet by plural predetermined speeds, among which one speed is selected according to a mode. ### Claim 35 (depends on 34) An automatic original feeding apparatus according to claim 34, wherein said rotary member stops, after conveying the sheet by a small amount, and then conveys the sheet again.