JP2011046504A - Paper carrying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper carrying device capable of further stably carrying paper. <P>SOLUTION: A digital complex machine 10 carries first paper 51 from a paper feeding cassette 25 in response to a requested size (S12) when accepting an image forming request (S11), and next, calculates to which position a stopping position of the tip 53 of second paper 52 becomes (S15) after calculating an inter-paper distance (S14), and here, determines whether or not the stopping position of the tip 53 of the calculated second paper 52 coincides with a position of a paper detecting sensor 42 (S16), and delays the carrying starting timing of the second paper 52 (S17) when determining that the stopping position of the tip 53 of the calculated second paper 52 coincides with the position of the paper detecting sensor 42 (YES in S16). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus, and more particularly to a sheet conveying apparatus capable of sequentially conveying a plurality of sheets and an image forming apparatus including such a sheet conveying apparatus.

  In the image forming apparatus, when an image is formed, the paper stored in the paper feed cassette is conveyed to an image forming unit that forms an image. The image formed in the image forming unit is transferred to a sheet, and after fixing, the sheet is discharged out of the apparatus.

  The image forming apparatus is provided with a sheet conveying device that conveys the above-described sheet in the apparatus. In general, the sheet conveying apparatus includes a sheet conveying path, a plurality of conveying rollers, and the like.

  Note that a technique related to sheet conveyance in the image forming apparatus is disclosed in Japanese Patent Laid-Open No. 8-2735 (Patent Document 1) and Japanese Patent Laid-Open No. 3-6574 (Patent Document 2). According to Patent Document 1, driving of a plurality of sheet material conveying means can be controlled by one clutch means. According to Patent Document 2, the next paper is fed out after a time corresponding to the minimum necessary paper interval.

JP-A-8-2735 Japanese Patent Laid-Open No. 3-6574

  In the paper transport path, paper detection sensors for detecting whether or not the paper has passed through the positions at a predetermined timing are provided at a plurality of locations. Whether or not the sheet has passed a predetermined location in the sheet conveyance path can be detected based on whether or not the detection timing by the sheet detection sensor is appropriate.

  In response to a request for image formation, a sheet to be printed is conveyed from the paper feed cassette to the image forming unit. The conveyed paper is temporarily put on standby in front of the image forming unit in order to match the timing of image formation and the timing of transfer onto the paper. Then, the sheet is conveyed to the image forming unit in accordance with the image formation timing.

  When continuous printing is requested, a plurality of sheets are sequentially conveyed to the image forming unit. In this case, the preceding sheet, that is, the sheet on the downstream side in the sheet conveying direction is spaced from the preceding sheet by a predetermined interval, and the next sheet is also conveyed into the sheet conveying path. Note that the sheet interval is not constant and varies depending on required image forming conditions.

  Here, as shown in Patent Document 1, when the image forming apparatus is configured such that a plurality of drive mechanisms are interlocked, the next sheet is also stopped together with the preceding sheet. Then, the position where the next sheet stops, specifically, for example, the position where the leading edge of the next sheet stops may be the position where the sheet detection sensor is provided. As a result, if the timing of starting the conveyance of the next sheet is slightly shifted, the sheet detection sensor may be irregularly operated. Specifically, the irregular operation means that the detection by the paper detection sensor is repeatedly turned on and off while the paper is stopped, is turned on before the paper is stopped, and is turned off when the paper is stopped. Say. Under such circumstances, the paper cannot be stably conveyed.

  An object of the present invention is to provide a paper transport device that can transport paper more stably.

  Another object of the present invention is to provide an image forming apparatus capable of forming an image more stably.

  The paper transport device according to the present invention is a paper transport device capable of sequentially transporting the first and second papers, and is provided at a predetermined position in the paper transport path and a paper transport path serving as a paper transport path. A sheet detection sensor for detecting whether or not there is a sheet at a predetermined position, a first sheet transport unit for transporting the first sheet, and a first sheet transport unit after the first sheet transport unit is activated. Calculated by a second sheet conveying unit that conveys the second sheet, a calculation unit that calculates in advance a stop position of the second sheet when the first sheet is stopped in the sheet conveyance path, and a calculation unit A determination unit that determines whether the stop position of the second sheet coincides with a predetermined position where the sheet detection sensor is provided, and the stop position of the second sheet coincides with the predetermined position by the determination unit. If it is determined, the timing of the start of transport of the second sheet And control means for controlling the second sheet conveying means so as to vary the predetermined timing.

  Preferably, the determination unit determines whether or not the stop position of the end region in the conveyance direction of the second sheet coincides with a predetermined position, and the control unit determines the end region in the conveyance direction of the second sheet. If the stop position coincides with the predetermined position, it is activated.

  Further, the end region is preferably a region having a length of ± 10% of the length in the paper transport direction from the end of the paper.

  As a further preferred embodiment, the paper transport means includes a transport roller that is provided in the paper transport path and nips the paper and transports the paper by rotation.

  In another aspect of the present invention, an image forming apparatus is an image forming apparatus including an image forming unit that forms an image, and a sheet transporting device that can sequentially transport a plurality of sheets to the image forming unit. The apparatus is a sheet conveying apparatus capable of sequentially conveying the first and second sheets, and is provided at a predetermined position in the sheet conveying path and a sheet conveying path serving as a path for conveying the sheet. A sheet detection sensor that detects whether or not there is a sheet, a first sheet conveying unit that conveys the first sheet, and a second sheet is conveyed at a predetermined timing after the first sheet conveying unit is activated. A second paper conveying means for calculating, a calculating means for calculating in advance a stop position of the second paper when the first paper is stopped in the paper conveying path, and a stop of the second paper calculated by the calculating means The position is the same as the predetermined position where the paper detection sensor is provided. If the determination means for determining whether or not the stop position of the second sheet coincides with the predetermined position by the determination means, the timing for starting the conveyance of the second sheet is made different from the predetermined timing. Control means for controlling the second paper conveying means.

  With this configuration, when the first sheet stops, the second sheet surely stops at a position where the sheet detection sensor is not provided. Then, the paper detection sensor does not operate irregularly in relation to the stop position of the second paper. Accordingly, it is possible to transport the paper more stably.

  In addition, the image forming apparatus having such a configuration includes a sheet conveying apparatus that can convey the sheet more stably, and thus can form an image more stably.

1 is a block diagram illustrating an overall configuration of a digital multi-function peripheral including a paper transport device according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a part of a sheet conveying device provided in a digital multifunction peripheral according to an embodiment of the present invention. FIG. 3 is an enlarged view of a portion indicated by III in FIG. 2 in the paper transport device shown in FIG. 2. 4 is a flowchart illustrating an operation of a control unit when image formation is performed in the digital multifunction peripheral according to the embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a digital multifunction peripheral 10 when an image forming apparatus including a sheet conveying device according to an embodiment of the present invention is applied to the digital multifunction peripheral 10.

  Referring to FIG. 1, a digital multifunction device 10 includes a CPU, a control unit 11 that controls the entire digital multifunction device 10, a DRAM 12 for writing and reading image data and the like, and a digital multifunction device 10. An operation unit 13 that serves as an interface with the user in the digital multifunction peripheral 10, a document feeder 14 that automatically transports a document to a predetermined document reading position, and a document feeder 14. An image reading unit 15 that reads an image of a conveyed document at a predetermined reading position, a photosensitive member 23 that forms an electrostatic latent image thereon, and an electrostatic latent image formed on the photosensitive member 23 such as toner. An image forming unit 16 that includes a developing unit 24 that supplies a developer to form a visible image and forms the image from a document read by the image reading unit 15; A hard disk 17 to be stored, a FAX communication unit 18 connected to a public line 20, a network IF (interface) unit 19 for connection to a network 21, a paper feed cassette 25 for storing a plurality of sheets, and a digital multi-function peripheral 10 includes a discharge tray 26 for discharging the sheet to the outside, and a sheet conveying device 27 for conveying the sheet from the sheet feeding cassette 25 to the discharge tray 26 via the image forming unit 16. The description and specific configuration of the sheet transport device 27 will be described later.

  The control unit 11 compresses and writes the original data output from the image reading unit 15 in the DRAM 12, reads the data written in the DRAM 12, decompresses and encodes the data, and outputs it by the image forming unit 16.

  The digital multi-function peripheral 10 operates as a copier by forming an image in the image forming section 16 via the DRAM 12 using the document read by the image reading section 15. Further, the digital multifunction peripheral 10 forms an image in the image forming unit 16 via the DRAM 12 using the image data transmitted from the personal computer 22 connected to the network 21 through the network IF unit 19, thereby serving as a printer. Operate. Further, the digital multifunction peripheral 10 forms an image in the image forming unit 16 through the DRAM 12 using the image data transmitted from the public line 20 through the FAX communication unit 18, and also by the image reading unit 15. The image data of the read original is transmitted to the public line 20 through the FAX communication unit 18 to operate as a facsimile machine.

  In FIG. 1, thick arrows indicate the flow of image data, and thin arrows indicate the flow of control signals or control data.

  Next, a specific configuration of the paper transport device 27 will be described. FIG. 2 is a schematic cross-sectional view schematically showing a part of the paper transport device 27. In FIG. 2, the digital multifunction peripheral 10, the image forming unit 16, the paper feed cassette 25, and the discharge tray 26 are indicated by a one-dot chain line.

With reference to FIGS. 1 to 3, the paper transport device 27 includes a paper transport path 28 provided from the paper feed cassette 25 through the image forming unit 16 to the discharge tray 26. The paper transport path 28 is a paper path provided with a gap between the first guide member 29 and the second guide member 30 configured by a plurality of flat plate members and the like. The sheet is conveyed from a sheet feeding cassette 25 provided on the lower side in FIG. 2 toward an image forming unit 16 provided on the upper side in FIG. Thereafter, the sheet is conveyed from the image forming unit 16 to a discharge tray 26 provided outside the digital multifunction peripheral 10. In the region between the paper feed cassette 25 and the image forming unit 16, the paper feed cassette 25 side is the upstream side in the transport direction, and the image forming unit 16 side is the downstream side in the transport direction. Incidentally, an arrow A ₁ in FIG. 2, showing a conveyance direction of the sheet. In the actual configuration of the digital multi-function peripheral 10 with respect to the paper conveyance path 28, it is bent halfway in the left-right direction in FIG. 2, but from the viewpoint of easy understanding, it extends straight in the vertical direction in FIG. It is shown in the figure.

  A plurality of pairs of transport rollers 31, 32, and 33 are provided in the middle of the paper transport path 28 from the paper feed cassette 25 to the image forming unit 16. Specifically, a total of three pairs of first transport rollers 31, a pair of second transport rollers 32, and a pair of third transport rollers from the upstream side are provided at predetermined intervals in the transport direction. It has been.

The configuration of the first conveying roller 31 will be described. The left and right rollers 34 and 35 constituting the pair of first conveying rollers 31 are each made of an elastic member, and the left and right rollers 34 and 35 are respectively formed on the sheet conveying path. 28 so as to nip at 28. The left and right rollers 34 and 35 rotate in the directions of arrows B ₁ and B ₂ in FIG. By the rotation of the left and right rollers 34 and 35, the sheet conveyed between the rollers 34 and 35 is nipped, and the sheet is conveyed from the lower side to the upper side in FIG. Note that the configuration of the pair of second conveyance rollers 32 and the pair of third conveyance rollers 33 is the same as the configuration of the pair of second conveyance rollers 31, and thus description thereof is omitted.

  Further, the paper transport device 27 includes a plurality of paper detection sensors 41, 42, and 43 that are provided at predetermined positions in the paper transport path 28 and detect whether or not there is a paper at the predetermined positions. Specifically, in this embodiment, the first paper detection sensor 41 is provided at a position in front of the first conveyance roller 31 on the upstream side in the conveyance direction, and the second paper detection sensor 42 is provided in the second conveyance direction. A third paper detection sensor 43 is provided at a position before the upstream side of the third transport roller 33 in the transport direction.

  Here, paper detection by the paper detection sensor will be described with reference to FIG. FIG. 3 is an enlarged view of a part of the paper transport device 27 shown in FIG. 2, and is an enlarged view of the vicinity of the second paper detection sensor 42 indicated by III in FIG.

  Referring to FIG. 3, paper detection sensor 42 is rotatable about a rotation shaft 45 having a shape extending in the front and back direction of the paper surface in FIG. 3 toward the paper conveyance direction indicated by the direction of arrow C in FIG. A claw portion 44 is included. Specifically, the claw portion 44 is rotatable from the position indicated by the dotted line in FIG. 3 to the position indicated by the solid line. The second guide member 30 is provided with a recess 46 for receiving the rotated claw portion 44 indicated by a solid line in FIG.

  The claw portion 44 is provided by a biasing force of a spring (not shown) or the like so as to be in a position indicated by a dotted line in FIG. 3 normally, that is, in a state where the paper 47 is not conveyed. Specifically, the tip 48 of the claw 44 is a position aligned with the rotating shaft 45 in a substantially horizontal direction. The state of the claw portion 44 is detected as a state where the paper 47 is not conveyed, that is, a state where the paper 47 is not at a position where the paper detection sensor 42 is provided. Then, when the sheet 47 is conveyed to the position where the second sheet detection sensor 42 is provided by the first conveying roller 31 or the like, the claw portion 44 is pushed by the sheet 47 and is indicated by a solid line in FIG. As described above, the rotation shaft 45 is rotated. The state of the claw portion 44 is detected as a state where the paper 47 is being conveyed, that is, a state where the paper 47 is in a position where the second paper detection sensor 42 is provided. Specifically, the tip 48 of the claw portion 44 is a position that is obliquely above the rotation shaft 45 with respect to the substantially horizontal direction.

  The paper transport device 27 determines whether the paper 47 has reached the position where the paper detection sensor 42 is provided after a predetermined time has elapsed from the start of the transport of the paper 47, and the paper detection sensor 42 is turned on. By detecting whether or not the paper 47 has passed and the paper detection sensor 42 is turned off, it is detected whether or not the paper 47 has properly passed the position where the paper detection sensor 42 is provided.

  A pair of registration rollers 36 is provided on the downstream side of the paper conveyance path 28 and on the front side in the conveyance direction upstream of the image forming unit 16. The pair of registration rollers 36 is also made of an elastic member, like the pair of first transport rollers 31 described above, and transports the paper into the image forming unit 16 by its rotation. A pair of pickup rollers 37 are provided on the upstream side of the paper transport path 28 and on the downstream side of the paper feed cassette 25 in the transport direction to pick up paper from the paper feed cassette 25 and supply it to the paper transport path 28. Yes. The pair of pickup rollers 37 is also made of an elastic member, like the pair of first transport rollers 31 described above, and transports the paper into the paper transport path 28 by its rotation.

  That is, the paper transport device 27 includes a paper transport path 28, transport rollers 31 to 33 as paper transport means, a registration roller 36 and a pickup roller 37, and whether or not there is a paper at a predetermined position in the paper transport path 28. Paper detection sensors 41 to 43 for detecting the above.

  Here, with respect to the image forming unit 16, an electrostatic latent image is formed by the photosensitive member 23, and a developer such as toner is supplied by the developing device 24 to form a visible image from the electrostatic latent image formed on the photosensitive member 23. Form. Then, a visible image made of toner is transferred onto a sheet and fixed. It is necessary to transport the sheet to the image forming unit 16 at a timing when a visible image is formed in the image forming unit 16. Accordingly, the sheet is conveyed to the position of the registration roller 36 by the conveyance roller 31 and the like, the sheet is waited by the registration roller 36, and the sheet is transferred from the position of the registration roller 36 to the image forming unit 16 at the timing when the visible image is formed with toner. Conveys and transfers visible image with toner onto paper. Then, after fixing, the image is discharged out of the digital multifunction peripheral 10.

  In the digital multi-function peripheral 10, a belt (not shown) that transmits driving to each of the first conveying roller 31, the second conveying roller 32, and the third conveying roller 33 by one motor (not shown). Etc.) and the like are simultaneously driven to rotate. That is, the operations of the transport rollers 31 to 33 in the region surrounded by the two-dot chain line in FIG. 2 are the same. Specifically, the transport rollers 31 to 33 start rotating at the same time and stop rotating at the same time. The sheet conveying device 27 having such a configuration is simplified in comparison with a configuration in which each of the first to third conveying rollers 31 to 33 is provided with a rotation driving motor and is controlled separately. Can be planned.

  Next, a case where image formation is performed in the digital multifunction peripheral 10 according to an embodiment of the present invention will be described. Here, a request for forming a plurality of images is accepted. FIG. 4 is a flowchart showing the operation of the control unit 11 in this case.

  1 to 4, the digital multifunction peripheral 10 first receives a request for forming a plurality of images from the user via the display screen of the operation unit 13 (step S11 in FIG. , Omit the steps). Regarding the request for image formation, the user inputs various conditions such as a desired number of sheets, a paper size, a desired image density, and the like. The control unit 11 accepts various conditions for image formation as well as requests for image formation.

  Then, the paper transport device 27 transports the first sheet from the paper feed cassette 25 according to the requested size (S12). Here, the first sheet is referred to as the first sheet 51. In this case, since it is necessary to transport the first paper 51 into the image forming unit 16 in synchronism with the visible image formed in the image forming unit 16, the registration roller provided in front of the image forming unit 16 described above. In 36, the conveyance of the first paper 51 is once stopped. That is, the first paper 51 is put on standby at the position of the registration roller 36 until the formation of the visible image by the image forming unit 16 is completed.

  On the other hand, upon receiving an image formation request, the digital multifunction peripheral 10 starts image formation. Specifically, a plurality of documents set on the document feeder 14 by the user are sent to the image reading unit 15. Then, the image reading unit 15 reads the original image one by one. Thereafter, based on the read image, the image forming unit 16 forms a visible image with toner (S13).

  Here, since a request for forming a plurality of images is made, the sheet conveying device 27 prepares to sequentially convey the second sheet following the first sheet. Here, the second sheet is referred to as a second sheet 52.

  As preparation for transporting the second paper 52, the distance in the transport direction between the first paper 51 and the second paper 52, that is, between the first paper 51 and the second paper 52, The distance is calculated (S14). Regarding the distance between the first sheet 51 and the second sheet 52, the required image condition, for example, color, monochrome, enlarged image or reduced image is required. It is calculated based on the paper size and the like.

  Next, after calculating the distance between the sheets, the position at which the leading end 53 of the second sheet 52 is stopped is calculated (S15). That is, the first paper 51 is registered on the registration roller 36 based on the conveyance start timing of the second paper 52 calculated from the distance between the papers calculated as described above and the length of the first paper 51. It is calculated at which position in the transport direction the leading edge 53 of the second paper 52 stops when stopped.

  Here, it is determined whether or not the calculated stop position of the leading end 53 of the second sheet 52 matches the position of the sheet detection sensor 42 (S16).

  If it is determined that the calculated stop position of the leading end 53 of the second sheet 52 coincides with the position of the sheet detection sensor 42 (YES in S16), the conveyance start timing of the second sheet 52 is different. Make it. Specifically, the conveyance start timing of the second sheet 52 is delayed from the conveyance start timing calculated from the distance between the sheets and the length of the first sheet 51 in the conveyance direction (S17).

  Then, the conveyance of the second paper 52 is started. Then, image formation is performed by performing subsequent image formation and transfer of a visible image to a sheet (S18).

  On the other hand, when it is determined that the stop position of the leading end 53 of the second sheet 52 does not coincide with the position of the sheet detection sensor 42 (NO in S16), the timing for starting the conveyance of the second sheet 52 is not delayed. That is, the conveyance of the second sheet 52 is started so as to be the conveyance start timing calculated from the distance between the sheets and the length of the first sheet 51 in the conveyance direction (S19). Thereafter, image formation is performed (S18).

  According to the sheet transport device 27 having such a configuration, when the first sheet 51 is stopped, the second sheet 52 is surely stopped at a position where the sheet detection sensor 42 is not provided. Then, the paper detection sensor 42 does not operate irregularly in relation to the stop position of the second paper 52. Accordingly, it is possible to transport the paper more stably.

  In addition, since the digital multi-function peripheral 10 having such a configuration includes the paper transport device 27 that can transport paper more stably, it is possible to form an image more stably.

  In the above embodiment, it is calculated whether or not the sheet detection sensor is positioned at the leading edge of the second sheet. However, the present invention is not limited to this, and it is determined whether or not the sheet detection sensor is positioned at the trailing edge of the sheet. You may decide to calculate. Also, it may be calculated whether or not it is located at either the leading edge or the trailing edge of the sheet. By doing so, it is possible to prevent the irregular operation of the sheet detection sensor and to convey the sheet stably. Furthermore, it may be calculated whether or not the sheet exists at the position of the sheet detection sensor instead of either the leading edge or the trailing edge of the sheet. That is, the stop position of the second sheet is set to a position avoiding the sheet detection sensor. By doing so, the paper can be conveyed more stably.

  Here, in the above embodiment, it is determined whether or not the leading edge of the sheet coincides with the position where the sheet detection sensor is provided, and the timing for starting the conveyance of the second sheet is delayed. Whether or not the timing of starting the conveyance of the second sheet is made different by determining whether or not the end area of the leading end of the second sheet coincides with the position where the sheet detection sensor is provided. You may make it decide. By doing so, it is possible to more reliably prevent a conveyance failure or the like due to an irregular operation of the paper detection sensor. Note that the end region is preferably a region having a length of ± 5% of the length in the sheet conveyance direction from the end of the sheet, that is, the front end or the rear end. Further, the end area is preferably an area having a length of ± 10% of the length in the paper transport direction from the end of the paper. With this configuration, it is possible to transport the paper more stably according to the configuration of the digital multifunction peripheral 10 or the like.

  In the above-described embodiment, the first, second, and third transport rollers are interlocked. However, the present invention is not limited to this, and the first, second, and third transport rollers are separately provided. The present invention is also applied to the case where it is rotationally driven.

  In the above-described embodiment, the conveyance roller that nips the sheet and conveys the sheet by rotation is used as the sheet conveyance unit. However, the present invention is not limited to this. For example, a belt-shaped conveyance member is used. Alternatively, a conveyance member that conveys the sheet so as to move the sheet by suction or the like may be used.

  In the above embodiment, the paper detection sensor including the claw portion is used as the paper detection sensor. However, the paper detection sensor is not limited to the paper detection sensor having such a configuration. The second guide member is always irradiated with light from the first guide member, and is detected using a PI (Photo Interrupter) sensor or the like that detects a light shielding amount that changes according to the passage of the paper at the attachment position. Also good.

  In the above embodiment, the paper transport device is controlled by the control unit included in the digital multifunction peripheral. However, the present invention is not limited to this, and the paper transport device has its own control unit. The entire section may be controlled by the section.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  DESCRIPTION OF SYMBOLS 10 Digital multifunction device, 11 Control part, 12 DRAM, 13 Operation part, 14 Document feeder, 15 Image reading part, 16 Image formation part, 17 Hard disk, 18 FAX communication part, 19 Network IF part, 20 Public line, 21 Network , 22 PC, 23 photoconductor, 24 developing device, 25 paper feed cassette, 26 discharge tray, 27 paper transport device, 28 paper transport path, 29, 30 guide member, 31, 32, 33 transport roller, 34, 35 roller, 36 Registration roller, 37 Pickup roller, 41, 42, 43 Paper detection sensor, 44 Claw part, 45 Rotating shaft, 46 Recess, 47, 51, 52 Paper, 48, 53 Tip.

Claims (5)

A paper transport device capable of sequentially transporting first and second paper,
A paper transport path as a path for transporting paper;
A paper detection sensor that is provided at a predetermined position in the paper transport path and detects whether or not there is a paper at the predetermined position;
First paper transport means for transporting the first paper;
A second paper conveying means for conveying the second paper at a predetermined timing after the first paper conveying means is activated;
Calculating means for calculating in advance a stop position of the second sheet when the first sheet is stopped in the sheet conveyance path;
Determination means for determining whether the stop position of the second paper calculated by the calculation means coincides with the predetermined position where the paper detection sensor is provided;
If the determination unit determines that the stop position of the second sheet coincides with the predetermined position, the second sheet is made to have a timing for starting the conveyance of the second sheet different from the predetermined timing. A sheet conveying apparatus comprising: control means for controlling the conveying means. The determination unit determines whether or not a stop position of the end region in the conveyance direction of the second sheet coincides with the predetermined position;
2. The sheet conveying apparatus according to claim 1, wherein the control unit is activated when a stop position of an end region in the conveyance direction of the second sheet coincides with the predetermined position. The sheet conveying apparatus according to claim 2, wherein the end area is an area having a length of ± 10% of a length in a conveyance direction of the sheet from an end of the sheet. The paper transport device according to claim 1, wherein the paper transport unit includes a transport roller that is provided in the paper transport path and that nips the paper and transports the paper by rotation. An image forming apparatus comprising: an image forming unit that forms an image; and a sheet conveying device that can sequentially convey a plurality of sheets to the image forming unit,
The paper transport device is a paper transport device capable of sequentially transporting first and second paper,
A paper transport path as a path for transporting paper;
A paper detection sensor that is provided at a predetermined position in the paper transport path and detects whether or not there is a paper at the predetermined position;
First paper transport means for transporting the first paper;
A second paper conveying means for conveying the second paper at a predetermined timing after the first paper conveying means is activated;
Calculating means for calculating in advance a stop position of the second sheet when the first sheet is stopped in the sheet conveyance path;
Determination means for determining whether the stop position of the second paper calculated by the calculation means coincides with the predetermined position where the paper detection sensor is provided;
If the determination unit determines that the stop position of the second sheet coincides with the predetermined position, the second sheet is made to have a timing for starting the conveyance of the second sheet different from the predetermined timing. An image forming apparatus comprising: a control unit that controls the conveying unit.

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