US20070075483A1 - Sheet conveying apparatus and image forming apparatus - Google Patents

Sheet conveying apparatus and image forming apparatus Download PDF

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Publication number
US20070075483A1
US20070075483A1 US11/459,045 US45904506A US2007075483A1 US 20070075483 A1 US20070075483 A1 US 20070075483A1 US 45904506 A US45904506 A US 45904506A US 2007075483 A1 US2007075483 A1 US 2007075483A1
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United States
Prior art keywords
skew feed
sheet
pair
amount
skew
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Abandoned
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US11/459,045
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English (en)
Inventor
Hiromasa Katayama
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Canon Inc
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Canon Inc
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Publication date
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Assigned to CANON KABUSHIKI KAISHA reassignment CANON KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KATAYAMA, HIROMASA
Publication of US20070075483A1 publication Critical patent/US20070075483A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H5/00—Feeding articles separated from piles; Feeding articles to machines
    • B65H5/02—Feeding articles separated from piles; Feeding articles to machines by belts or chains, e.g. between belts or chains
    • B65H5/021—Feeding articles separated from piles; Feeding articles to machines by belts or chains, e.g. between belts or chains by belts
    • B65H5/025—Feeding articles separated from piles; Feeding articles to machines by belts or chains, e.g. between belts or chains by belts between belts and rotary means, e.g. rollers, drums, cylinders or balls, forming a transport nip
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H9/00—Registering, e.g. orientating, articles; Devices therefor
    • B65H9/002—Registering, e.g. orientating, articles; Devices therefor changing orientation of sheet by only controlling movement of the forwarding means, i.e. without the use of stop or register wall
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2301/00—Handling processes for sheets or webs
    • B65H2301/30—Orientation, displacement, position of the handled material
    • B65H2301/33—Modifying, selecting, changing orientation
    • B65H2301/331—Skewing, correcting skew, i.e. changing slightly orientation of material

Definitions

  • the present invention relates to a sheet conveying apparatus, and more particularly, to a sheet conveying apparatus for correcting skew feed of a sheet such as a recording sheet or an original conveyed to an image forming portion or an image reading portion.
  • an image forming apparatus or an image reading apparatus such as a copying machine, a printer, or a facsimile apparatus
  • a sheet conveying apparatus for conveying a sheet such as a recording sheet or an original to an image forming portion or an image reading portion.
  • Some of such sheet conveying apparatuses are equipped with a skew feed correcting unit for effecting sheet skew feed correction to correctly adjust the attitude and position of the sheet until the sheet is conveyed to the image forming portion or the image reading portion.
  • a leading edge of a sheet is caused to abut a nip of a roller pair at rest to generate bending in the sheet, and the leading edge of the sheet is caused to extend along the roller nip by utilizing an elasticity of the sheet, thereby correcting skew feed.
  • a shutter member is retractably provided in a sheet conveying path, and the leading edge of a sheet conveyed is caused to abut the shutter member -to thereby effect skew feed correction. In the system using the shutter member, there is no need to stop the sheet being conveyed, so it is possible to reduce an interval between the sheets, making it possible to enhance throughput in image formation, etc.
  • FIG. 8 shows an example of a conventional skew feed correcting unit for correcting skew feed of a sheet by such the active skew feed correction system.
  • Two sheet leading edge detecting sensors 201 a and 201 b are provided in a sheet conveying path.
  • the two sheet leading edge detecting sensors 201 a and 201 b are arranged in a direction (i.e., width direction of the sheet being conveyed) which is perpendicular to the sheet conveying direction indicated by an arrow A.
  • skew feed correcting rollers 222 a and 222 b are provided.
  • the skew feed correcting rollers 222 a and 222 b are arranged in the direction perpendicular to the sheet conveying direction and coaxially at a predetermined interval.
  • the skew feed correcting rollers 222 a and 222 b are driven independently by separate drive sources 221 a and 221 b, respectively.
  • this skew feed correcting unit constructed as described above, when a leading edge of a sheet S conveyed from a downstream side traverses the sheet leading edge sensors 201 a and 201 b , signals are output from the sheet leading edge detecting sensors 201 a and 201 b , respectively. Based on those leading edge detecting signals, the skew feed amount (i.e., skew angle) of the sheet leading edge is calculated, and, based on the calculated value, rotating speeds of the skew feed correcting rollers 222 a and 222 b are respectively controlled to thereby correct the skew feed of the sheet S.
  • the skew feed amount i.e., skew angle
  • the sheet is turned by an amount corresponding to the skew feed amount to thereby correct the skew feed.
  • FIG. 9 is a control block diagram showing the skew feed correcting unit.
  • a skew feed amount detecting portion 215 is formed by the two sheet leading edge detecting sensors 201 a and 201 b and a skew feed detecting portion 200 .
  • the sheet leading edge detection signals from the sheet leading edge detecting sensors 201 a and 201 b are input to the skew feed detecting portion 200 , which outputs a skew feed detection signal to a control portion 210 .
  • control portion 210 calculates the skew feed amount by a skew feed amount calculating portion 210 a based on the skew feed detection signal. Further, after that, based on the calculated skew feed amount, the respective rotating speeds of two skew feed correcting portions 220 formed by the skew feed correcting rollers 222 a and 222 b and the drive sources 221 a and 221 b are determined by a control amount calculating portion 210 b . By driving the skew feed correcting rollers 222 a and 222 b at the respective determined rotating speeds, skew feed correction is effected on the sheet.
  • this control involves the following problem: the respective rotating speeds of the skew feed correcting rollers 222 a and 222 b are determined based on the detection signals from the skew feed amount detecting portion 215 formed by the sheet leading edge detecting sensors 201 a and 201 b and the skew feed detecting portion 200 , and the skew feed is corrected according to a difference in the speed at which the sheet is conveyed by the skew feed correcting rollers 222 a and 222 b .
  • the sheet conveying speeds may differ from those when the rollers were in initial states, resulting in a deterioration in accuracy in skew feed correction.
  • FIG. 12 is a side view of a skew feed correcting portion.
  • FIG. 11 is a block diagram showing such the skew feed correcting unit.
  • a skew feed amount detecting portion 315 is formed by two line sensors 301 a and 301 b and a skew feed detecting portion 300 .
  • Sheet leading edge detection signals from the line sensors 301 a and 301 b are input to the skew feed detecting portion 300 , and the skew feed detecting portion 300 outputs a skew feed detection signal to a control portion 310 .
  • control portion 310 calculates the skew feed amount based on the skew feed detection signal by a skew feed amount calculating portion 310 a . Further, after that, based on the skew feed amount calculated, the respective rotating speeds of two skew feed correcting portions 320 , formed by skew feed correcting rollers 322 a and 322 b and drive sources 321 a and 321 b , are determined by a control amount calculating portion 310 b .
  • the skew feed correcting rollers 322 a and 322 b are driven at the determined rotating speeds, and the sheet is turned according to a difference in sheet conveying speed between the skew feed correcting rollers 322 a and 322 b to thereby effect skew feed correction.
  • the conventional sheet conveying apparatus equipped with a skew feed correcting unit using the line sensors 301 a and 301 b has the following problems.
  • the line sensors 301 a and 301 b -to extend to an image transfer position, which locates between a photosensitive drum 21 and a transfer charger 22 shown in FIG. 12 , with the result that there is generated a conveying section Y where the skew feed correction is impossible.
  • the skew feed correcting rollers 321 a and 321 b may involve a difference in conveying amount as a result of long-term use. When such the difference in conveying amount is generated, there is a possibility of skew feed being newly generated in the conveying section Y.
  • the method using the line sensors 301 a and 301 b involves limitations in terms of arrangement, and cannot be easily applied to an image forming apparatus, such as a copying machine or a printer, or an image reading apparatus, such as a scanner, which is nowadays being increasingly reduced in size.
  • the present invention has been made in view of the above-mentioned problems in the conventional art. It is therefore an object of the present invention to provide a sheet conveying apparatus, an image forming apparatus, and an image reading apparatus capable of realizing a reduction in size and performing sheet skew feed correction with high accuracy.
  • a sheet conveying apparatus including:
  • a skew feed amount detecting portion configured to detect a skew feed amount of a sheet
  • a pair of skew feed correcting portions arranged in a direction perpendicular to a sheet conveying direction, configured to correct skew feed of the sheet by conveying the sheet through independent rotations;
  • a conveying amount detecting portion configured to detect the respective sheet conveying amounts of the skew feed correcting portions
  • control portion configured to control rotations of the skew feed correcting portions according to detection results obtained by the skew feed amount detecting portion and the conveying amount detecting portion
  • the control portion calculates a sheet correction amount by which the skew feed of the sheet is to be corrected by the pair of skew feed correcting portions based on a detection result obtained by the conveying amount detecting portion, and controls the rotations of the skew feed correcting portions such that the sheet correction amount becomes equal to the skew feed amount of the sheet detected by the skew feed amount detecting portion.
  • FIG. 1 is a sectional view of a printer constituting an example of an image forming apparatus equipped with a sheet conveying apparatus according to a first embodiment of the present invention
  • FIG. 2 is a perspective view showing the construction of a skew feed correcting unit provided in the sheet conveying apparatus
  • FIG. 3 is a block diagram showing the skew feed correcting unit
  • FIG. 4 is a side view of the skew feed correcting unit
  • FIG. 5 is a perspective view of a skew feed correcting unit provided in a sheet conveying apparatus according to a second embodiment of the present invention.
  • FIG. 6 is a block diagram of the skew feed correcting unit
  • FIG. 7 is a side view of the skew feed correcting unit
  • FIG. 8 is a perspective view showing the construction of a conventional skew feed correcting unit
  • FIG. 9 is a block diagram showing the conventional skew feed correcting unit
  • FIG. 10 is a perspective view showing the construction of another conventional skew feed correcting unit
  • FIG. 11 is a block diagram of still another conventional skew feed correcting -unit.
  • FIG. 12 is a side view of still another conventional skew feed correcting unit.
  • FIG. 1 is a sectional view of a printer, which constitutes an example of an image forming apparatus equipped with a sheet conveying apparatus according to the first embodiment of the present invention.
  • a printer 1 which is an image forming apparatus, is equipped with a printer main body 2 provided with an image forming portion 3 , a scanner 11 arranged on the upper surface of the printer main body 2 , and a feeding deck 12 which is arranged on one side of the printer main body 2 and which accommodates a large amount of sheets S in a stacked state.
  • the printer main body 2 is equipped with the image forming portion 3 provided with a photosensitive drum 21 serving as the image bearing member, and retard separation type sheet feeding apparatuses 1 . 6 and 17 for feeding the sheets S. Further, the printer main body 2 is equipped with a sheet conveying apparatus 4 for conveying the sheets S.,which are fed by the sheet feeding apparatuses 16 and 17 , to the image forming portion 3 .
  • the sheet feeding apparatuses 16 and 17 are equipped with cassettes 13 and 14 containing a plurality of sheets S, feeding rollers 16 a and 17 a for sending out the sheets S from the cassettes 13 and 14 , and the like.
  • the sheet conveying apparatus 4 is equipped with a conveying roller 41 and a skew feed correcting unit 18 , and the sheets S sent out from the sheet feeding apparatuses 16 and 17 are sent to the skew feed correcting unit 18 by the conveying roller 41 .
  • the sheets contained in the feeding deck 12 are sent out by a feeding roller 10 , and sent to the skew feed correcting unit 18 by a retard separation type sheet feeding apparatus 15 and a conveying roller 12 a.
  • the sheet S is transmitted to a transfer portion of the image forming portion 3 , which is formed by the photosensitive drum 21 and the transfer charger 22 . Then, at the transfer portion, a toner image previously formed on the photosensitive drum 21 is transferred. After that, the sheet S to which the toner image has been transferred is sent to a fixing device 24 by a conveyor belt 23 , and the transferred toner image is fixed to the sheet S by the fixing device 24 .
  • the printer 1 is provided with a two-sided copying mode in which copying is performed on both sides of the sheet S.
  • the normal copying mode i.e., one-side copying mode
  • the sheet S that has undergone the fixing process is delivered onto a delivery tray 27 outside the printer 1 by a delivery roller pair 26 .
  • the sheet S is temporarily stacked on an intermediate tray 31 by an in-delivery roller pair 25 or a switchback roller pair 29 through a re-feed path 28 and a duplex transport path 30 .
  • the sheet S placed on the intermediate tray 31 is conveyed to the skew feed correcting unit 18 again by the re-feeding apparatus 32 for image formation, and from this onward, the sheet S undergoes the same process as in the one-side copying mode before being delivered to the outside.
  • FIG. 2 is a perspective view of the skew feed correcting unit 18 .
  • two optical sheet leading edge detecting sensors 101 a and 101 b are arranged at a fixed interval in a direction (i.e., width direction of the sheet being conveyed) which is perpendicular to the sheet conveying direction indicated by an arrow A.
  • Driving rollers 122 a and 122 b are arranged coaxially in a direction perpendicular to the sheet conveying direction indicated by the arrow A and independently driven by pulse motors 121 a and 121 b serving as drive sources.
  • Conveyor belts 123 a and 123 b are respectively stretched between the driving rollers 122 a and 122 b , and driven rollers 124 a and 124 b arranged on the upstream side of the driving rollers 122 a and 122 b .
  • Driven rotary members 131 a and 13 !b are held in press contact with the conveyor belts 123 a and 123 b by a pressurizing device (not shown).
  • the driven rotary members 131 a and 131 b are associated with the rotation of the conveyor belts 123 a and 123 b to rotate respectively.
  • the driving rollers 122 a and 122 b , the driven rollers 124 a and 124 b , the conveyor belts 123 a and 123 b , and the driven rotary members 131 a and 131 b constitute a pair of right and left skew feed correcting portions 18 a and 18 b.
  • a curved path is formed by the conveyor belts 123 a and 123 b and the driven rotary members 131 a and 131 b arranged on the inner side, making it possible to correct skew feed while conveying the sheet in a curved state.
  • the sheet S sent out and conveyed by the sheet feeding apparatuses 15 , 16 , and 17 is conveyed while being nipped by the conveyor belts 123 a and 123 b , and the driven rotary members 131 a and 131 b.
  • Rotary encoders 132 a and 132 b are rotation amount detecting portions connected to the driven rotary members 131 a and 131 b .
  • the respective rotation amounts of the driven rotary members 131 a and 131 b are detected by the rotary encoders 132 a and 132 b.
  • FIG. 3 is a control block diagram showing the skew feed correcting unit 18 , constructed as described above.
  • a skew feed amount detecting portion 105 for detecting the skew feed amount (i.e., skew angle) of the sheet is formed by the two sheet leading edge detecting sensors 101 a and 101 b serving as sheet detecting devices and a skew feed detecting portion 100 to which signals from the sheet leading edge detecting sensors 101 a and 101 b are input.
  • a control portion 110 calculates the skew feed amount of the sheet based on a signal from the skew feed detecting portion 100 , and which determines the respective control amounts of the driving rollers 122 a and 122 b for the skew feed correcting portions 18 a and 18 b to correct the skew feed of the sheet based on the calculated skew feed amount.
  • the control amounts of the driving rollers 122 a and 122 b are the respective rotating speeds of the driving rollers 122 a and 122 b for correcting the skew feed of the sheet S in a predetermined period of time. That is, in the control portion, there is calculated the amount by which the sheet is to be conveyed by the conveyor belts 123 a and 123 b to correct the skew feed of the sheet in a predetermined period of time. Then, the respective rotating speeds of the driving rollers 122 a and 122 b are set such that the sheet conveying amount of the conveyor belts 123 a and 123 b is the calculated sheet conveying amount.
  • the control portion 110 is equipped with a comparing portion 110 c and a storage portion 110 d described below.
  • FIG. 4 is a side view of the skew feed correcting unit 18 .
  • the sheet S which is conveyed from the downstream side by the sheet feeding apparatuses 15 , 16 , and 17 , is conveyed along a curved path which is formed by arranging the conveyor belts 123 a and 123 b on the outer side and arranging the driven rotary members 131 a and 131 b on the inner side. Then, the leading edge of the sheet S traverses the sheet leading edge detecting sensors 101 a and 101 b . As a result, the sheet leading edge detecting sensors 101 a and 101 b output signals indicating the traversing of the sheet to the skew feed detecting portion 100 .
  • the detection signals are output from the sheet leading edge detecting sensors 101 a and 101 b to the skew feed detecting portion 100 with different timings.
  • the skew feed detecting portion 100 When the detection signals are thus output with different timings, the skew feed detecting portion 100 outputs an instantaneous skew feed detection signal to the control portion 110 , and the control portion 110 calculates the skew feed amount (i.e., skew angle) by a skew feed amount calculating portion 110 a based on the skew feed detection signal. Based on the skew feed amount thus calculated, the respective control amounts for the skew feed correcting portions 18 a and 18 b of the skew feed correcting unit 18 are determined by a control amount calculating portion 110 b .
  • the skew feed amount i.e., skew angle
  • the amount by which the sheet is to be conveyed by the conveyor belts 123 a and 123 b in the predetermined period of time to correct the skew feed amount of the sheet S is calculated, and the respective rotating speeds of the driving rollers 122 a and 122 b for achieving this are determined.
  • the respective rotating speeds of the pulse motors 121 a and 121 b are controlled, and the conveyor belt 123 a of the front-side skew feed correcting portion 18 a and the conveyor belt 123 b of the depth-side skew feed correcting portion 18 b , shown in FIG. 2 , are driven for a predetermined period of time with a difference in sheet conveying speed (i.e., peripheral speed).
  • a difference in sheet conveying speed i.e., peripheral speed
  • This difference in sheet conveying speed (i.e., peripheral speed) may be controlled so as to be always at a fixed value, or may be controlled such that the difference in sheet conveying speed is increased according to the skew feed amount.
  • skew feed correction can also be effected by performing control to delay the advancing end portion side of the sheet S, control to promote the delayed end portion side thereof, or both controls. Further, control is possible if the pulse motors 121 a and 121 b serving as the drive sources are DC motors or AC motors.
  • the difference in detection value between the rotary encoders 132 a and 132 b corresponds to a difference in the amount by which the sheet is conveyed by the conveyor belts 123 a and 123 b , so this difference constitutes the correction amount to be obtained through actual correction on the sheet S. Then, the detection value detected by the conveying amount detecting portion 130 including the driven rotary members 131 a and 131 b and the rotary encoders 132 a and 132 b is output to the control portion 110 , where the actual difference in sheet conveying amount is calculated as the correction amount result.
  • the comparing portion 110 c of the control portion 110 compares the actual correction amount result with the skew feed amount which is detected by the skew feed amount detecting portion 105 and then calculated by the skew feed amount calculating portion 110 a . Then, a judgment is made as to whether the skew feed correction has been effected to a sufficient degree or as to whether overshoot (i.e., getting beyond the proper position) in skew feed correction has been generated or not.
  • the difference in the amount by which the sheet is conveyed by the conveyor belts 123 a and 123 b is calculated from the skew feed amount of the sheet S.
  • the difference between this calculated sheet conveying amount and the actual sheet conveying amount input from the conveying amount detecting portion 130 are compared with each other to make a judgment as to whether the skew feed correction has been performed properly or not.
  • the difference in the sheet conveying speed i.e., peripheral speed
  • the pulse motors 121 a and 121 b are controlled such that the relationship of the difference in the sheet conveying speed is reversed. This operation is continued until the calculated sheet conveying amount and the actual sheet conveying amount become equal to each other; even after they are judged to be equal, correction control is conducted again when any skew feed of the sheet is detected.
  • control portion 110 can calculate the actual sheet skew feed correction amount (i.e., correction angle) from the detection value detected by the conveying amount detecting portion 130 , and to compare the correction amount with the skew feed amount (i.e., skew angle) calculated by the skew feed amount calculating portion 110 a based on the skew feed detection signal from the skew feed detecting portion 100 . Based on this comparison, a judgment is made as to whether the sheet skew feed correction is proper or not. In this case also, when the comparison result shows that the skew feed amount is insufficient, the difference in conveying speed (i.e., peripheral speed) at which the sheet is conveyed by the conveyor belts 123 a and 123 b is maintained.
  • conveying speed i.e., peripheral speed
  • the pulse motors 121 a and 121 b are controlled such that the relationship of the difference in sheet conveying speed is reversed. Then, this operation is continued until the skew angle based on the detection by the skew feed detecting portion 100 and the actually corrected correction angle become equal to each other. Even after those angles are judged to be equal, correction control is conducted again if any skew feed of the sheet is detected.
  • This operation can be continued through the correction section X from the moment that skew feed of the leading edge of the sheet is detected at the detecting position P 1 shown in FIG. 4 to the moment that the leading edge of the sheet reaches the transfer portion formed by the photosensitive drum 21 and the transfer charger 22 .
  • the rotational accuracy of the driven rotary members 131 a and 131 b is strictly controlled, and variation in the rotation of the conveyor belts 123 a and 123 b is stored in the storage port-on 110 d provided in the control portion 110 , controlling the pulse motors 121 a and 121 b so as to cancel the variation in rotation.
  • the difference in the sheet conveying amount between the skew feed correcting portions 18 a and 18 b of the skew feed correcting unit 18 is detected based on a signal from the conveying amount detecting portion 130 . Then, the skew feed correcting portions 18 a and 18 b of the skew feed correcting unit 18 are controlled such that the difference in the detected sheet conveying amount becomes equal to the skew feed amount detected by the skew feed detecting portion 105 .
  • the rotation center of the driven rotary members 131 a and 131 b and of the rotary encoders 132 a and 132 b is provided at a center of a circle along which the curved sheet conveying path (i.e., curved path) L extends.
  • the curved sheet conveying path i.e., curved path
  • the contact area between the conveyor belts 123 a and 123 b and the sheet S and the driven rotary members 131 a and 131 b is increased.
  • the conveying amount detecting portion 130 is formed not by the rotary encoders 132 a and 132 b and the driven rotary members 131 a and 131 b but by the rotary encoders 132 a and 132 b and the conveyor belts 123 a and 123 b .
  • both may be provided as a belt structure.
  • FIG. 5 is a perspective view of a skew feed correcting unit provided in a sheet conveying apparatus according to an embodiment of the present invention
  • FIG. 6 is a block diagram thereof.
  • the reference symbols that are the same as those of FIGS. 2 and 3 indicate the same or equivalent components.
  • skew feed correcting rollers 125 a and 125 b constitute a pair of skew feed correcting portions 20 a and 20 b of a skew feed correcting unit 20 .
  • the skew feed correcting rollers 125 a and 125 b are arranged coaxially in a direction perpendicular to the sheet conveying direction indicated by the arrow A, and are driven independently by pulse motors 121 a and 121 b serving as the drive sources.
  • Conveying rotary members 126 a and 126 b are held in press contact with the skew feed correcting rollers 125 a and 125 b by a pressurizing device (not shown).
  • the sheet S conveyed by the sheet feeding apparatuses 15 , 16 , and 17 is conveyed while being sandwiched between the conveying rotary members 126 a and 126 b and the skew feed correcting rollers 125 a and 125 b.
  • the axial width of the skew feed correcting rollers 125 a and 125 b is larger than the axial width of the conveying rotary members 126 a and 126 b . Due to this difference in width, there are generated, in the skew feed correcting rollers 125 a and 125 b , portions that are not in contact with the conveying rotary members 126 a and 126 b , and laser Doppler type sensors 133 a and 133 b are arranged so as to face these portions.
  • the laser Doppler type sensors 133 a and 133 b are sensors capable of detecting fluctuation in the speed of an object in a non-contact fashion. By using the sensors 133 a and 133 b , it is possible to detect the conveying speed of the sheet S. Further, the sensors 133 a and 133 b are adapted to undergo a change in output when the sheet S is conveyed thereto. Due to this change in output, it is possible to detect any sheet S conveyed thereto.
  • the skew feed amount detecting portion also serves as the conveying amount detecting portion, and the skew feed amount detecting portion 115 of the present invention is formed by the sensors 133 a and 133 b and the skew feed detecting portion 100 .
  • the skew feed correcting unit 20 constructed as described above, when the sheet S conveyed by the sheet feeding apparatuses 15 , 16 , and 17 is conveyed to the detecting point P 2 of the sensors 133 a and 133 b as shown in FIG. 7 , the values detected by the sensors 133 a and 133 b change.
  • the leading edge of the sheet S traverses the two sensors 133 a and 133 b with different timings, whereby detection signals are output from the sensors 133 a and 133 b with different timings.
  • the skew feed detection signals are input to the skew feed detecting portion 100 shown in FIG. 6 from the sensors 133 a and 133 b , and the skew feed detecting portion 100 outputs an instantaneous skew feed detection signal to the control portion 110 .
  • the control portion 110 calculates the skew feed amount based on this skew feed detection signal.
  • control amount means a rotating speed set for each of the skew feed correcting rollers 125 a and 125 b in order to correct the skew feed of the sheet S in a predetermined period of time.
  • the rotating speeds of the pulse motors 121 a and 121 b are controlled to produce a difference in a rotating speed between the front-side skew feed correcting roller 125 a and the depth-side skew feed correcting roller 125 b , thereby producing a difference in the sheet conveying amount between the front side and the depth side. In this way, the sheet S is turned, and the skew feed thereof is corrected.
  • the sheet conveying speeds (i.e., peripheral speeds) of the front-side skew feed correcting roller 125 a and the depth-side skew feed correcting roller 125 b are respectively detected by the sensors 133 a and 133 b .
  • the sheet conveying amount based on the detection result it is possible to detect the actual correction amount.
  • the comparing portion 110 c of the control portion 110 compares the actual correction result input from the sensors 133 a and 133 b , also serving as the conveying amount detecting portion, with the skew feed amount detected by the skew feed amount detecting portion 115 and calculated by the skew feed amount calculating portion 110 a . In this way, it is checked whether the skew feed correction has been effected to a sufficient degree, or whether any overshoot in a skew feed correction has been generated or not.
  • the pulse motors 121 a and 121 b are controlled so as to reverse the relationship of the difference in the sheet conveying speed. This operation is continued until the skew feed amount becomes equal to the correction amount. Even after the skew feed amount and the correction amount are judged to be equal, correction control is conducted again if any skew feed of the sheet is detected.
  • a difference in the sheet conveying amount of the skew feed correcting unit is detected based on the detection by the conveying amount detecting portion, and the skew feed correcting unit is controlled such that the difference in the sheet conveying amount detected becomes equal to the skew feed amount detected.
  • the width of the conveying rotary members 126 a and 126 b is made larger than that of the skew feed correcting rollers 125 a and 125 b .
  • the sheet conveying apparatus of the present invention is provided in a printer (i.e., image forming apparatus).
  • a printer i.e., image forming apparatus
  • the apparatus according to the present invention should not be construed restrictively.
  • the present invention is also applicable, for example, to an image reading apparatus, such as a scanner, which is equipped with an image reading portion for reading the image of an original.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Registering Or Overturning Sheets (AREA)
  • Controlling Sheets Or Webs (AREA)
US11/459,045 2005-07-28 2006-07-21 Sheet conveying apparatus and image forming apparatus Abandoned US20070075483A1 (en)

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JP2005-218847 2005-07-28
JP2005218847A JP4641460B2 (ja) 2005-07-28 2005-07-28 シート搬送装置及び画像形成装置並びに画像読取装置

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US20080309989A1 (en) * 2005-09-28 2008-12-18 Brother Kogyo Kabushiki Kaisha Image reading apparatus
EP3020667A1 (en) * 2014-11-13 2016-05-18 Seiko Epson Corporation Transportation apparatus and recording apparatus
US20190161299A1 (en) * 2017-11-30 2019-05-30 Ricoh Company, Ltd. Sheet conveying device, image forming apparatus incorporating the sheet conveying device, method of conveying conveyance target medium, and method of forming image on conveyance target medium using the method of forming image

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JP2008285297A (ja) * 2007-05-18 2008-11-27 Canon Inc シート搬送装置及び画像形成装置並びに画像読取装置
JP5460222B2 (ja) * 2009-10-05 2014-04-02 キヤノン株式会社 画像形成装置及びシート搬送方法
JP2011093622A (ja) * 2009-10-27 2011-05-12 Fuji Xerox Co Ltd 画像形成装置
JP6365510B2 (ja) * 2015-11-10 2018-08-01 Ｊｆｅスチール株式会社 搬送状態検出装置
JP7182061B2 (ja) * 2018-03-06 2022-12-02 株式会社リコー 搬送装置、画像形成装置、搬送方法、及び画像形成方法
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