JP5514761B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding device that feeds a sheet toward a predetermined processing position, and an image forming apparatus that includes the sheet feeding device as an automatic document feeding device.

  The sheet feeding device has a function of picking up a plurality of sheets stacked and placed on a tray one by one and sending them out to a conveyance path. For example, an automatic document feeding device (ADF: Auto) of an image forming apparatus. Used as Document Feeder). If the automatic document feeder is used, the image forming apparatus can automatically and continuously scan a plurality of document sheets.

  The automatic document feeder includes a pickup roller, a separation mechanism (feed belt, separation roller), a registration roller, a conveyance roller, and the like arranged in order from the upstream side of the conveyance path (see, for example, Patent Document 1). The pickup roller picks up the uppermost document sheet from the plurality of document sheets placed on the tray. The separation mechanism separates the extracted uppermost original sheet from the lower original sheet, and sends out only the uppermost original sheet to the conveyance path. The registration roller corrects the inclination of the document sheet so that the document sheet sent to the conveyance path is not conveyed obliquely. The original sheet whose inclination is corrected by the registration roller is conveyed on the conveyance path by the conveyance roller and is sent to the image reading position.

JP 2007-197196 A

  If the sheet interval between the original sheet transported on the transport path and the next original sheet to be sent to the transport path is reduced and the original sheets are continuously sent to the transport path, feeding of the first original sheet is started and the last is started. It is possible to shorten the time until the document sheet is completely fed.

  A feed switch is used to determine the timing for sending out the next document sheet. On the condition that the feed switch detects the trailing edge of the document sheet conveyed on the conveyance path (the feed switch switches from on to off), the timing for sending the next document sheet to the conveyance path is determined. Therefore, in order to reduce the sheet interval between the original sheet conveyed on the conveyance path and the original sheet sent next to the conveyance path, it is necessary to dispose the feed switch on the upstream side of the conveyance path.

  However, since the separation mechanism described above is disposed upstream of the conveyance path, the feed switch is disposed side by side with the separation mechanism. Since the separation mechanism is arranged on the center line of the conveyance path, if the feed switch is arranged side by side with the separation mechanism, a small original sheet (for example, a postcard) may not be detected by the feed switch.

  For a small original sheet, if the long side of the original sheet is perpendicular to the conveying direction, even a small original sheet can be detected by the feed switch. However, since the short side of the document sheet is in the transport direction, it is necessary to increase the number of transport rollers.

  In the above prior art, since the feed switch is arranged downstream of the conveyance path from the separation mechanism, even a small-size original sheet can be detected, but the distance between the original sheets can be reduced and continuously sent to the conveyance path. Can not.

  In the present invention, a plurality of sheets having a predetermined size or more can be continuously sent out to the conveying path with a small sheet interval, and a plurality of sheets smaller than a predetermined size can be continuously sent. It is an object of the present invention to provide a sheet feeding device that can be sent out to a conveyance path and an image forming apparatus including the sheet feeding device.

  An image forming apparatus according to one aspect of the present invention that achieves the above object includes a tray on which a sheet to be fed is placed, a conveyance path, and a plurality of sheets stacked on the tray. A separating mechanism that separates the uppermost sheet from a lower sheet; a feeding unit that feeds the sheet placed on the tray to the conveyance path; and a conveyance direction of the sheet conveyed through the conveyance path The first detection means that is arranged side by side with the separation mechanism in a direction crossing the line and can detect a sheet having a predetermined size or more out of the sheets conveyed on the conveyance path, and cannot be detected by the first detection means A position where a sheet smaller than the predetermined size can be detected, and a second detection means provided downstream of the conveying path from the separation mechanism, and a plurality of sheets having a predetermined size or more. A first mode in which a sheet is continuously sent from the tray to the transport path, and a second mode in which a plurality of sheets smaller than the predetermined size are continuously sent from the tray to the transport path. A paper control unit, and in the first mode, the paper feed control unit is configured on the condition that a rear end of a sheet conveyed on the conveyance path is detected by the first detection unit. In the second mode, the next sheet is sent out from the tray to the conveyance path, and in the second mode, on the condition that the sheet conveyed through the conveyance path is detected by the second detection means. The sending means feeds the next sheet from the tray to the conveyance path.

  In the sheet feeding device according to one aspect of the present invention, when a plurality of sheets having a predetermined size or more that can be detected by the first detection unit are continuously sent out from the tray to the conveyance path (in the first mode). In the case where the trailing edge of the sheet conveyed on the conveyance path is detected by the first detection unit, the next sheet is sent from the tray to the conveyance path and cannot be detected by the first detection unit. When a plurality of sheets smaller than the predetermined size are continuously sent from the tray to the conveyance path (in the second mode), on condition that the sheet conveyed through the conveyance path is detected by the second detection unit, The next sheet is sent out from the tray to the conveyance path. As described above, according to one aspect of the present invention, when the first detection unit is arranged side by side with the separation mechanism to reduce the sheet interval, the first detection unit cannot detect the size of the sheet. The next sheet is fed out on condition that it is detected using the second detecting means. Therefore, for a plurality of sheets having a predetermined size or more, the sheet interval can be continuously reduced and sent to the conveyance path, and for a plurality of sheets having a size smaller than the predetermined size, It can be sent out to the conveyance path.

  In the above configuration, in the case of the second mode, the long side direction of the sheet conveyed through the conveyance path is set to the conveyance direction.

  According to this configuration, since the sheet having a smaller size than the predetermined size has the long side direction of the sheet as the transport direction, the sheet can be transported without increasing the number of transport rollers.

  In the above configuration, the conveyance path is a conveyance path that passes through an image reading position where an image on one surface of the conveyed sheet is optically read, and is upstream of the image reading position and the second path. A contact-type image sensor that is disposed in the transport path downstream from the detection unit and reads an image on the other surface of the sheet transported through the transport path is further provided, and the second detection unit is configured to transport the transport by the image sensor. This is used for timing detection when an image on the other surface of the sheet conveyed on the path is read.

  According to this configuration, the detection means used for detecting the timing when the image on the other surface of the sheet conveyed on the conveyance path by the contact-type imaging device is read is the second detection means. For this reason, it is not necessary to newly provide a second detection means in order to detect an original sheet smaller than a predetermined size. The contact-type image sensor refers to, for example, a CIS (Contact Image Sensor).

  Further, according to this configuration, since the contact-type image sensor is arranged upstream from the image reading position, the second detection unit is compared with the case where the contact-type image sensor is arranged downstream from the image reading position. Can be arranged upstream of the transport path. Therefore, a plurality of sheets smaller than a predetermined size can be continuously sent out to the conveyance path with a reduced sheet interval as compared with the case where the contact-type imaging device is arranged downstream from the image reading position. It becomes possible.

  In the above configuration, a registration roller disposed in the conveyance path downstream from the separation mechanism and upstream from the second detection unit, and a registration drive that rotates the registration roller under the control of the paper feed control unit. And, in the first mode, the sheet feeding control unit controls the feeding unit to send the sheet placed on the tray to the conveyance path, and the sheet is transferred by the registration roller. After correcting the inclination, the registration driving unit is controlled to rotate the registration roller to convey the sheet downstream of the conveyance path. In the second mode, the feeding unit is controlled to control the feeding unit. The registration roller is rotated by controlling the registration driving means at the same time as or earlier than the start of feeding the sheet placed on the tray to the conveyance path. So it allows conveying the sheet to the downstream of the conveying path.

  By detecting the leading edge of the sheet with the first detection means and stopping the feeding means at a predetermined timing, the sheet is bent with the leading edge of the sheet applied to the registration roller. Thereby, the inclination of the leading edge of the sheet is corrected by the registration roller. In the second mode, since the sheet cannot be detected by the first detection unit, the sheet is sent downstream of the conveyance path without correcting the inclination of the leading edge of the sheet by the registration roller. If the registration roller is rotated after the operation of the feeding means, the sheet may be stopped by the registration roller, and the sheet may be jammed in the conveyance path. According to this configuration, since the registration roller is rotated simultaneously with or faster than the operation of the feeding unit, it is possible to prevent the registration roller from jamming the sheet.

  In the above-described configuration, in the second mode, the sheet feeding control unit controls the sending unit on the condition that the leading edge of the sheet conveyed on the conveyance path is detected by the second detecting unit. Then, the next sheet is sent out from the tray to the conveyance path.

  According to this configuration, when the trailing edge of the sheet conveyed on the conveyance path is detected by the second detection unit, the feeding unit is controlled to send the next sheet from the tray to the conveyance path. In comparison, the sheet interval can be shortened.

  An image forming apparatus according to another aspect of the present invention includes the sheet feeding device, an image reading unit that reads an image of a sheet fed from the sheet feeding device, and an image read by the image reading unit. An apparatus main body that forms and outputs on a sheet.

  The image forming apparatus according to another aspect of the present invention has the same operation as that of the sheet feeding apparatus according to one aspect of the present invention described above.

  According to the present invention, for a plurality of sheets having a predetermined size or more, the sheet interval can be reduced and continuously sent to the conveyance path, and also for a plurality of sheets having a size smaller than the predetermined size. , Can be continuously sent out to the conveyance path.

1 is a perspective view illustrating an appearance of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing an appearance of an automatic document feeder provided in the image forming apparatus shown in FIG. 1. FIG. 2 is a cross-sectional view illustrating an internal structure of the image forming apparatus illustrated in FIG. 1. FIG. 3 is a perspective view showing a state in which an upper cover is removed in the document conveying portion of the automatic document feeder shown in FIG. 2. FIG. 3 is a schematic cross-sectional view of a document conveying portion of the automatic document feeder shown in FIG. 2. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus illustrated in FIG. 1. 5 is a flowchart (part 1) of an example of a first mode executed by a paper feed control unit. 10 is a flowchart (part 2) of an example of a first mode executed by the paper feed control unit. 10 is a flowchart of an example of a second mode executed by the paper feed control unit. It is a schematic diagram which shows operation | movement of an example of the mechanical switch which can be used as a 1st and 2nd detection means.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an appearance of an image forming apparatus 1 according to an embodiment of the present invention, FIG. 2 is a perspective view showing an appearance of an automatic document feeder 3, and FIG. 3 is an internal view of the image forming apparatus 1. It is sectional drawing which shows a structure. Here, the in-body discharge type copier is illustrated as the image forming apparatus 1, but the image forming apparatus may be a printer, a facsimile machine, or a multifunction machine having these functions.

  The image forming apparatus 1 includes an apparatus main body 2 having a substantially rectangular parallelepiped housing structure and having an in-cylinder space (in-cylinder discharge unit 24), an automatic document feeder 3 disposed on the upper surface of the apparatus main body 2, And an additional sheet feeding unit 4 assembled on the lower side of the apparatus main body 2.

  The apparatus main body 2 performs an image forming process on the sheet. The apparatus main body 2 includes a substantially rectangular parallelepiped lower casing 21, a substantially rectangular parallelepiped upper casing 22 disposed above the lower casing 21, and a connection that connects the lower casing 21 and the upper casing 22. And a housing 23. The lower housing 21 accommodates various devices for image formation, and the upper housing 22 accommodates an image reading unit 5 for optically reading a document image. An in-cylinder space surrounded by the lower casing 21, the upper casing 22, and the connecting casing 23 serves as an in-cylinder discharge unit 24 that can store a sheet after image formation. The connection housing 23 is disposed on the right side surface of the apparatus main body 2 and is provided with a discharge port 961 for discharging the sheet to the in-body discharge unit 24.

  The in-cylinder space used as the in-cylinder sheet discharge unit 24 is open to the outside on the front surface and the left side surface of the apparatus main body 2. The user can insert a hand from these open portions and take out the sheet after image formation from the in-body sheet discharge unit 24. A bottom surface 241 of the in-cylinder space is partitioned by the upper surface of the lower housing 21 and a sheet discharged from the discharge port 961 is stacked thereon.

  An operation panel unit 25 protrudes from the front surface of the upper housing 22. The operation panel unit 25 includes an operation key 251 including a numeric keypad and a start key, an LCD touch panel 252 and the like, and accepts input of various operation instructions from the user. The user can input the number of sheets to be printed and the like and input the print density and the like through the operation panel unit 25.

  A paper feed cassette 211 that houses a recording sheet on which image forming processing is performed is mounted on the lower housing 21. The additional sheet feeding unit 4 also includes sheet feeding cassettes 41 and 42 that store recording sheets on which image forming processing is performed. These sheet feeding cassettes 211, 41, and 42 are cassettes provided for automatic sheet feeding, and can accommodate a large number of recording sheets according to size. Further, the paper feed cassettes 211, 41, and 42 can be pulled out from the front of the lower housing 21 or the additional paper feed unit 4. In FIG. 3, only the paper feed cassette 211 of the lower housing 21 is illustrated.

  A multi-tray unit M is mounted on the right side surface of the apparatus main body 2 for allowing the user to manually feed paper. The multi-tray unit M includes a paper feed tray 43 on which a manually fed recording sheet is placed, and a paper feeding unit 44 that carries the recording sheet into an image forming unit in the lower housing 21. The paper feed tray 43 is attached to the lower housing 21 at its lower end so as to be openable and closable, and is closed when not in use. When the user manually feeds paper, the user opens the paper feed tray 43 and places a recording sheet thereon.

  The automatic document feeder 3 is attached to the upper surface of the apparatus body 2 so as to be rotatable at the rear side. In FIG. 3, the description of the automatic document feeder 3 is omitted. The automatic document feeder 3 automatically feeds a document sheet to be copied toward a predetermined image reading position (a position where the first contact glass 222 is assembled) in the apparatus body 2. On the other hand, when the user manually places the document sheet on a predetermined image reading position (position of the second contact glass 223), the automatic document feeder 3 is opened upward.

  Referring to FIG. 2, the automatic document feeder 3 includes a main body housing 30 (housing), a document feeding tray 31 (tray), a document conveying section 32, a document discharge tray 33, and a document reversing tray 31B. The main body housing 30 is a housing that houses various mechanisms provided in the automatic document feeder 3, and has a front wall portion 301 and a rear wall that protrude upward from the left side portion that houses the document conveying portion 32. A portion 302 is provided, and a substantially flat low layer portion is provided on the right side portion.

  The document feed tray 31 is a tray on which a document sheet fed to the image reading position is placed, and is attached to the main body housing 30 so as to extend from the feeding port 30H of the main body housing 30. . The document feed tray 31 is provided with a pair of cursors 311 for adjusting the width of the placed document sheet.

  The document transport unit 32 includes a transport path and a transport mechanism for transporting the document sheet on the document feed tray 31 to the document discharge tray 33 via the image reading position. The document conveying section 32 includes an upper cover 32 </ b> U that is fitted into an opening between the front wall section 301 and the rear wall section 302 of the main body housing 30. These details will be described later with reference to FIG.

  The document discharge tray 33 is a tray from which a document sheet after a document image is optically read is discharged. An upper surface of the lower layer portion on the right side of the main body housing 30 is a document discharge tray 33. The document reversing tray 31B is a tray from which a document sheet is temporarily ejected when a document sheet having document images on both sides is read.

  Next, the internal structure of the apparatus main body 2 will be described with reference to FIG. In the lower casing 21, toner containers 99Y, 99M, 99C, and 99K, an intermediate transfer unit 92, an image forming unit 93, an exposure unit 94, and the above-described paper feed cassette 211 are accommodated in this order from the top.

  The image forming unit 93 forms four image forming units 10Y, 10M that form yellow (Y), magenta (M), cyan (C), and black (K) toner images in order to form a full-color toner image. 10C, 10K. Each of the image forming units 10Y, 10M, 10C, and 10K includes a photosensitive drum 11, and a charger 12, a developing device 13, a primary transfer roller 14, and a cleaning device 15 that are disposed around the photosensitive drum 11. .

  The photosensitive drum 11 rotates about its axis, and an electrostatic latent image and a toner image are formed on its peripheral surface. As the photosensitive drum 11, a photosensitive drum using an amorphous silicon (a-Si) material can be used. The charger 12 uniformly charges the surface of the photosensitive drum 11. The peripheral surface of the photosensitive drum 11 after charging is exposed by the exposure unit 94 to form an electrostatic latent image.

  The developing device 13 supplies toner to the peripheral surface of the photosensitive drum 11 in order to develop the electrostatic latent image formed on the photosensitive drum 11. The developing device 13 is for a two-component developer and includes stirring rollers 16 and 17, a magnetic roller 18, and a developing roller 19. The stirring rollers 16 and 17 charge the toner by circulating and conveying the two-component developer while stirring. A two-component developer layer is carried on the peripheral surface of the magnetic roller 18, and toner formed by transferring toner to the peripheral surface of the developing roller 19 due to a potential difference between the magnetic roller 18 and the developing roller 19. The layer is supported. The toner on the developing roller 19 is supplied to the peripheral surface of the photosensitive drum 11 and the electrostatic latent image is developed.

  The primary transfer roller 14 forms a nip portion with the photosensitive drum 11 across the intermediate transfer belt 921 provided in the intermediate transfer unit 92, and the toner image on the photosensitive drum 11 is primary transferred onto the intermediate transfer belt 921. To do. The cleaning device 15 cleans the peripheral surface of the photosensitive drum 11 after the toner image is transferred.

  The yellow toner container 99Y, the magenta toner container 99M, the cyan toner container 99C, and the black toner container 99K store toner of each color, and image forming units 10Y, 10M, and 10C corresponding to the respective colors of YMCK. Each color toner is supplied to the 10K developing device 13 through a supply path (not shown).

  The exposure unit 94 includes various optical system devices such as a light source, a polygon mirror, a reflection mirror, and a deflection mirror, and is provided on the peripheral surface of the photosensitive drum 11 provided in each of the image forming units 10Y, 10M, 10C, and 10K. The electrostatic latent image is formed by irradiating light based on the image data of the document image.

  The intermediate transfer unit 92 includes an intermediate transfer belt 921, a driving roller 922, and a driven roller 923. On the intermediate transfer belt 921, toner images are overcoated from the plurality of photosensitive drums 11 (primary transfer). The overcoated toner image is secondarily transferred to the recording sheet supplied from the paper feed cassette 211 by the secondary transfer unit 98. A driving roller 922 and a driven roller 923 that rotate the intermediate transfer belt 921 are rotatably supported by the lower casing 21.

  The paper feed cassette 211 (41, 42) stores a sheet bundle in which a plurality of recording sheets are stacked. A pickup roller 212 is disposed on the upper right side of the paper feed cassette 211. By driving the pickup roller 212, the uppermost recording sheet of the sheet bundle in the sheet feeding cassette 211 is fed out one by one and carried into the carry-in conveyance path 26. On the other hand, the manually fed recording sheet placed on the paper feed tray 43 is carried into the carry-in conveyance path 26 by driving the paper feed roller 45 of the paper feed unit 44.

  On the downstream side of the carry-in conveyance path 26, a sheet conveyance path 28 that extends to the discharge port 961 through the secondary transfer unit 98, a fixing unit 97 and a paper discharge unit 96 described later is provided. The upstream portion of the sheet conveyance path 28 is formed between an inner wall formed in the lower housing 21 and an inner wall that forms the inner surface of the reverse conveyance unit 29. The outer surface of the reverse conveyance unit 29 constitutes one side of a reverse conveyance path 291 that reversely conveys the sheet during duplex printing. A registration roller pair 27 is disposed on the upstream side of the sheet transfer path 28 from the secondary transfer unit 98. The sheet is temporarily stopped by the registration roller pair 27, and after skew correction is performed, the sheet is sent to the secondary transfer unit 98 at a predetermined timing for image transfer.

  A fixing unit 97 and a paper discharge unit 96 are accommodated in the connection housing 23. The fixing unit 97 includes a fixing roller and a pressure roller, and performs a fixing process by heating and pressing the recording sheet on which the toner image is secondarily transferred in the secondary transfer unit 98. The recording sheet with the color image that has been subjected to the fixing process is discharged from the discharge port 961 toward the in-body discharge unit 24 by a discharge unit 96 disposed downstream of the fixing unit 97.

  A first contact glass 222 and a second contact glass 223 are fitted on the upper surface of the upper housing 22. The first contact glass 222 is provided for reading a document sheet automatically fed from the automatic document feeder 3. Second contact glass 223 is provided for reading a manually placed document sheet.

  The image reading device 5 is accommodated in the upper housing 22. The image reading device 5 includes a scanning mechanism 224 and a CCD (Charge Coupled Device) 225 for optically reading document information on a document sheet. The scanning mechanism 224 includes a light source, a moving carriage, a reflection mirror, and the like, and guides reflected light from the document to the CCD 225. The CCD 225 photoelectrically converts the reflected light into an analog electric signal. The analog electric signal is converted into a digital electric signal by an A / D conversion circuit (not shown) and then input to the exposure unit 94.

  Next, the internal structure of the automatic document feeder 3 will be described in detail with reference to FIGS. FIG. 4 is a perspective view showing a state in which the upper cover 32U is removed from the document conveying section 32 of the automatic document feeder 3 shown in FIG. FIG. 5 is a schematic sectional view of the document conveying section 32 of the automatic document feeder 3 shown in FIG. The document sheet is a sheet having an image, and includes, for example, a paper sheet and an overhead projector (OHP) sheet.

  The document transport unit 32 includes a lift plate 320, a transport path 321, a pickup roller 324, a separation mechanism 325, a registration roller pair 326, transport roller pairs 327, 328, and 329 and a paper discharge roller pair 330.

  The conveyance path 321 includes a first conveyance path 321a, a second conveyance path 321b, and a third conveyance path 321c, which are arranged in order from the upstream in the direction in which the document sheet is conveyed. A document sheet placed on the document feed tray 31 passes through the first transport path 321a, the second transport path 321b, and the third transport path 321c, and is discharged onto the document discharge tray 33.

  The elevating plate 320 is located at the uppermost stream of the transport path 321 and is provided between the document feed tray 31 and the first transport path 321a so as to be lifted and lowered. The pickup roller 324 is disposed above the lift plate 320 at the boundary between the lift plate 320 and the first transport path 321a.

  The leading edge of the document sheet placed on the document feed tray 31 is positioned on the lift plate 320. The elevating plate 320 is raised to bring the leading end of the original sheet into contact with the pickup roller 324. When the pickup roller 324 rotates in this state, the document sheet placed on the document feed tray 31 (the uppermost document sheet in the case of a plurality of document sheets) is picked up, and the first transport path 321a. Sent out.

  A set switch PD1 is attached to the lower surface of the lifting plate 320 near the boundary between the lifting plate 320 and the first transport path 321a. The set switch PD1 is used to detect that the leading end portion of the document sheet placed on the document feed tray 31 is at a position facing the pickup roller 324. The set switch PD1 is, for example, an optical sensor, and its light receiving surface is positioned on the surface of the lifting plate 320.

  A plurality of size sensors used to determine the size of the document placed on the document feed tray 31 are attached to the lower surface of the elevation surface. In FIGS. 4 and 5, it is determined whether or not a document sheet (for example, a postcard) having a size smaller than A5 is placed on the document feed tray 31 with the long side direction set as the transport direction. The size sensor PD2 used is shown. The plurality of size sensors are, for example, optical sensors, and their light receiving surfaces are positioned on the surface of the lifting plate 320.

  The first transport path 321a has a linear shape. In the first conveyance path 321a, a separation mechanism 325 and a registration roller pair 326 are arranged in order from the upstream, and the first conveyance path 321a is separated in a direction intersecting with the conveyance direction of the original sheet conveyed. A feed switch PD3 is arranged side by side with the mechanism 325.

  The feed switch PD3 (an example of the first detection unit) is disposed above the first conveyance path 321a, and a document having a predetermined size or larger among document sheets conveyed through the first conveyance path 321a. This is used to detect the leading and trailing edges of a sheet (for example, an A5 size or larger original sheet). Hereinafter, a document sheet of A5 size or larger means a document sheet of a predetermined size or larger, and a document sheet smaller than the A5 size means a document sheet smaller than a predetermined size.

  Since the separation mechanism 325 is disposed on the center line of the first conveyance path 321a, an original sheet smaller than A5 size cannot pass below the feed switch PD3 when the long side direction is the conveyance direction. . Therefore, the feed switch PD3 cannot detect an original sheet smaller than A5 size in which the long side direction is the transport direction.

  The separation mechanism 325 is disposed on the center line of the first transport path 321a and in the vicinity of the pickup roller 324. The separation mechanism 325 includes a driving roller 325a, a driven roller 325b, an endless belt 325c, and a separation roller 325d. The driving roller 325a is located downstream of the driven roller 325b. An endless belt 325c is stretched between the driving roller 325a and the driven roller 325b, and these rollers function as a paper feeding roller. A separation roller 325d is disposed below the driving roller 325a and the driven roller 325b so as to press the endless belt 325c.

  The pickup roller 324 and the driving roller 325 a rotate in a direction in which the document sheet placed on the document feed tray 31 is sent out from the document feed tray 31. In contrast, the separation roller 325 d rotates in a direction to return the document sheet placed on the document feed tray 31 to the document feed tray 31. Accordingly, a plurality of document sheets taken one by one by the pickup roller 324 are prevented from being stacked and conveyed. That is, the separation mechanism 325 has a function of separating the uppermost document sheet from the document sheet below it when a plurality of document sheets are stacked and placed on the document feed tray 31.

  A registration roller pair 326 (an example of a registration roller) is disposed in the vicinity of the separation mechanism 325. The registration roller pair 326 includes a driving roller 326a and a driven roller 326b arranged so as to sandwich the document sheet. The document sheet conveyed from the separation mechanism 325 is corrected downstream by the registration roller pair 326 and conveyed downstream. More specifically, when the rotation of the registration roller pair 326 is stopped, the document sheet conveyed by the separation mechanism 325 has its leading end abutted against the registration roller pair 326 so that the leading end is parallel to the registration roller pair 326. By doing so, the inclination of the original sheet is corrected. The registration roller pair 326 is disposed in the conveyance path 321 downstream of the separation mechanism 325 and upstream of the CIS timing switch PD4 described later.

  A pair of transport rollers 327 is disposed at the boundary between the first transport path 321a and the second transport path 321b. The conveyance roller pair 327 includes a driving roller 327a and a driven roller 327b arranged so as to sandwich the document sheet. The document sheet conveyed from the registration roller pair 326 is conveyed to the second conveyance path 321b by the conveyance roller pair 327.

  The second conveyance path 321b has a curved shape that changes the conveyance direction of the document sheet by 180 degrees. In the second transport path 321b, a CIS timing switch PD4, a CIS 350, a CCD timing switch PD5, and a transport roller pair 328 are disposed in order from the upstream.

  A CIS (Contact Image Sensor) 350 reads an image on one side (back side) of a document sheet in close contact with the document sheet.

  The CIS timing switch PD4 (an example of the second detection unit) is disposed in the second transport path 321b. The CIS timing switch PD4 is used for detecting the leading edge of the document sheet conveyed through the second conveyance path 321b and determining the timing for reading one side (back surface) of the document sheet by the CIS.

  The CIS timing switch PD4 is an A5 size or larger document sheet (sheet of a predetermined size or more) that can be detected by the feed switch PD3, and a document sheet that is not detected by the feed switch PD3 and is smaller than the A5 size having the long side direction as the transport direction It is arranged at a position where any detection of (a sheet smaller than a predetermined size) is possible.

  The CCD timing switch PD5 detects the leading edge of the document sheet conveyed through the second conveyance path 321b, and is used to determine the timing for reading one side (front surface) of the document sheet by the CCD 225 (FIG. 3). The CIS timing switch PD4 and the CCD timing switch PD5 are, for example, optical sensors, and their light receiving surfaces are positioned on the surface of the second transport path 321b.

  The image reading position 351 is a position where an image is read when an image on one side (front surface) of the document sheet conveyed through the second conveyance path 321 b is read using the CCD 225. When the automatic document feeder 3 is closed with respect to the apparatus main body 2, the image reading position 351 faces the first contact glass 222.

  A conveyance roller pair 328 is disposed between the CCD timing switch PD5 and the image reading position 351. The conveyance roller pair 328 includes a driving roller 328a and a driven roller 328b arranged so as to sandwich the original sheet. The document sheet is conveyed on the second conveyance path 321b by the conveyance roller pair 328.

  A pair of conveyance rollers 329 is arranged at the boundary between the second conveyance path 321b and the third conveyance path 321c. The conveyance roller pair 329 includes a driving roller 329a and a driven roller 329b arranged so as to sandwich the document sheet. The document sheet that has been conveyed through the second conveyance path 321b is conveyed through the third conveyance path 321c by the conveyance roller pair 329.

  The third conveyance path 321c has a shape extending linearly and extending obliquely upward from the middle. A pair of paper discharge rollers 330 is disposed at the end of the third transport path 321c. The paper discharge roller pair 330 includes a driving roller 330a and a driven roller 330b arranged so as to sandwich the document sheet. The document sheet conveyed through the third conveyance path 321 c is sent to the document discharge tray 33 by the discharge roller pair 330.

  FIG. 6 is a block diagram illustrating a configuration of the image forming apparatus 1. The image forming apparatus 1 has a configuration in which an apparatus main body 2, an automatic document feeder 3, an image reading unit 5, an operation panel unit 25, and a control unit 500 are connected to each other by a bus. Since the apparatus main body 2, the image reading unit 5, and the operation panel unit 25 have already been described, description thereof will be omitted.

  As described above, the automatic document feeder 3 includes the set switch PD1, the size sensor PD2, the feed switch PD3, the CIS timing switch PD4, the CCD timing switch PD5, the pickup roller 324, the separation mechanism 325, the registration roller pair 326, and the conveyance. A roller pair 327, 328, 329, a paper discharge roller pair 330, and a CIS 350 are provided.

  The automatic document feeder 3 further includes a paper feed motor 340, a registration motor 341, a transport motor 342, and a paper discharge motor 343. The pickup roller 324 and the separation mechanism 325 are driven by the paper feed motor 340. The paper feed motor 340, the pickup roller 324, and the separation mechanism 325 constitute a sending unit 331. The sending unit 331 has a function of sending a document sheet placed on the document feed tray 31 to the conveyance path 321.

  The registration roller pair 326 is rotated by a registration motor 341 as an example of a registration driving unit, the conveyance roller pairs 327, 328, and 329 are rotated by the conveyance motor 342, and the discharge roller pair 330 is rotated by the discharge motor 343. It is done.

  The control unit 500 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an image memory, and the like. The CPU executes control necessary for operating the image forming apparatus 1 on the above-described components of the image forming apparatus 1 such as the apparatus main body 2. The ROM stores software necessary for controlling the operation of the image forming apparatus 1. The RAM is used for temporary storage of data generated during execution of software, storage of application software, and the like. The image memory temporarily stores image data (such as image data output from the image reading unit 5).

  The control unit 500 includes a paper feed control unit 501. The paper feed control unit 501 executes the first mode and the second mode. The first mode is a mode in which a plurality of document sheets of A5 size or larger (predetermined size or larger) are continuously sent from the document feed tray 31 to the conveyance path 321. The second mode is a mode in which a plurality of document sheets smaller than A5 size (smaller than a predetermined size) having the long side direction as the transport direction are continuously sent from the document feed tray 31 to the transport path 321. Say.

  In the first mode, the paper feed control unit 501 is configured to send out the feed unit 331 on the condition that the trailing edge of the document sheet conveyed on the conveyance path 321 is detected by the feed switch PD3 (first detection unit). Next, the next original sheet is sent out from the original feed tray 31 to the conveyance path 321. In the second mode, the original sheet conveyed on the conveyance path 321 is detected by the CIS timing switch PD4 (second detection means). If so, the sending means 331 sends the next document sheet from the document feed tray 31 to the transport path 321.

  The paper feed control unit 501 includes a counter 503. A paper feed motor 340, a registration motor 341, a transport motor 342, and a paper discharge motor 343 are stepping motors, and a counter 503 is used to count pulses for operating these motors.

  Next, the operation of the automatic document feeder 3 according to this embodiment will be described. 7 and 8 are flowcharts of an example of the first mode executed by the paper feed control unit 501. FIG. FIG. 9 is a flowchart of an example of the second mode executed by the paper feed control unit 501.

  First, the case of the first mode (when a document sheet of A5 size or larger is fed) will be described. The user places a plurality of document sheets on the document feed tray 31 in a stacked manner. Here, an example will be described in which an A4 size document D1 shown in FIG. 5 is placed on the document feed tray 31 with its long side in the transport direction. The paper feed control unit 501 determines whether or not the size sensor PD2 has detected a document sheet placed on the document feed tray 31 (step S1). As shown in FIG. 4, the size sensor PD2 does not detect a document sheet when a document sheet D2 smaller than A5 size is placed on the document feed tray 31 with its long side in the transport direction. Detects a document sheet placed on the document feed tray 31. In the present embodiment, the size sensor PD2 is used to determine the first mode or the second mode, but the user operates the operation panel unit 25 to change the first mode or the second mode. It may be selected.

  Since the A4 size document D1 placed on the document feed tray 31 is detected by the size sensor PD2 (Yes in step S1), the sheet feed control unit 501 determines to execute the first mode. . The user operates the operation panel unit 25 to select scan or copy, and presses the start button. Accordingly, the paper feed control unit 501 turns on the paper feed motor 340 (step S2). When the paper feed motor 340 is turned on, the sending means 331 sends the uppermost document sheet on the document feed tray 31 to the first transport path 321a.

  The paper feed controller 501 determines whether or not the feed switch PD3 is turned on (step S3). When the leading edge of the original sheet sent to the first conveyance path 321a passes under the feed switch PD3, the feed switch PD3 is turned on. When it is determined that the feed switch PD3 is not turned on (No in step S3), the paper feed control unit 501 repeats the process of step S3.

  When the paper feed control unit 501 determines that the feed switch PD3 is turned on (Yes in step S3), the counter 503 controls the pulse of the operation to operate the paper feed motor 340 in order to control the operation time of the paper feed motor 340. Counting is started (step S4).

  Since the paper feed motor 340 is rotating, the document sheet is conveyed by the sending means 331 through the first conveyance path 321 a and the leading edge of the document sheet hits the registration roller pair 326. Since the registration roller pair 326 is not rotated, the document sheet bends with the leading edge of the document sheet being in contact with the registration roller pair 326. As a result, the inclination of the leading edge of the document sheet is corrected. When the counter 503 described in step S4 counts up, the paper feed controller 501 turns off the paper feed motor 340 (step S5). As a result, the operation of the sending means 331 is stopped, so that the formation of the deflection of the original sheet is stopped. The time from the count start in step S4 to the count up in step S5 is the time required for the leading edge of the document sheet to hit the registration roller pair 326 to form a deflection on the document sheet (in other words, the inclination of the leading edge of the document sheet is corrected). The time it takes to do).

  In step S5, after the inclination of the leading edge of the original sheet is corrected by the registration roller pair 326, the paper feed control unit 501 turns on the paper feed motor 340, the resist motor 341, the transport motor 342, and the paper discharge motor 343 (see FIG. 5). Step S6).

  In order to control the operation time of the paper feed motor 340, the counter 503 starts counting pulses for operating the paper feed motor 340 (step S7). When the counter 503 described in step S7 counts up, the paper feed control unit 501 turns off the paper feed motor 340 (step S8). Thereby, after the trailing edge of the original sheet passes through the separation mechanism 325, the paper feed motor 340 is stopped, so that the next original sheet is prevented from being sent out to the first conveyance path 321a.

  The paper feed controller 501 determines whether or not the feed switch PD3 is turned off (step S9). When the trailing edge of the original sheet sent to the first transport path 321a passes under the feed switch PD3, the feed switch PD3 is turned off. If the paper feed control unit 501 determines that the feed switch PD3 is not turned off (No in step S9), the process in step S9 is repeated.

  If the paper feed control unit 501 determines that the feed switch PD3 has been turned off (Yes in step S9), the counter 503 counts the pulses for operating the registration motor 341 in order to control the operation time of the registration motor 341. Start (step S10). When the counter 503 described in step S10 counts up, the paper feed control unit 501 turns off the registration motor 341 (step S11). As a result, the registration motor 341 is stopped after the trailing edge of the document sheet has passed the registration roller pair 326.

  The paper feed control unit 501 determines whether the set switch PD1 is on (step S12). If the next document sheet is placed on the document feed tray 31, the set switch PD1 is turned on. If the next document sheet is not placed, the set switch PD1 is turned off.

  If the paper feed control unit 501 determines that the set switch PD1 is on (Yes in step S12), the process returns to step S1. As a result, the next document sheet placed on the document feed tray 31 is sent out to the first transport path 321 a by the sending means 331. On the other hand, the previous document sheet is transported along the transport path 321 by the transport roller pairs 327, 328, and 329 and the discharge roller pair 330 and is discharged to the document discharge tray 33 (step S13).

  When the paper feed controller 501 determines that the set switch PD1 is not turned on (No in step S12), the original sheet on the transport path 321 is transported by the transport roller pairs 327, 328, 329 and the discharge roller pair 330. Then, it is discharged to the document discharge tray 33 (step S14). Then, the paper feed control unit 501. The paper discharge motor 343 and the transport motor 342 are turned off (step S15). As a result, the rotation of the transport roller pair 327, 328, 329 and the discharge roller pair 330 is stopped.

  Next, the case of the second mode (when a document sheet smaller than A5 size is fed with its long side in the transport direction) will be described. A user places a plurality of document sheets on the document feed tray 31 in a stacked manner. Here, a document sheet D2 smaller than A5 size is placed on the document feed tray 31 with its long side in the transport direction. The paper feed controller 501 does not determine that the size sensor PD2 has detected the original sheet placed on the original paper feed tray 31 (No in step S1 in FIG. 7), so the paper feed controller 501 It is determined to execute the second mode. The user operates the operation panel unit 25, selects scan or copy, and presses the start button. As a result, the paper feed controller 501 turns on the paper feed motor 340, the registration motor 341, the transport motor 342, and the paper discharge motor 343 (step S21). When the paper feed motor 340 is turned on, the sending means 331 sends the uppermost document sheet on the document feed tray 31 to the first transport path 321a. In step S21, the counter 503 starts counting pulses for operating the paper feed motor 340 in order to control the operation time of the paper feed motor 340.

  In the second mode, an original sheet smaller than A5 size with the long side direction set as the transport direction is transported, and therefore the document sheet cannot be detected by the feed switch PD3. Accordingly, the document sheet is conveyed without correcting the inclination of the leading edge of the document sheet by the registration roller pair 326.

  The paper feed controller 501 turns off the paper feed motor 340 when the counter 503 described in step S21 counts up (step S22). Thereby, after the trailing edge of the original sheet passes through the separation mechanism 325, the paper feed motor 340 is stopped, so that the next original sheet is prevented from being sent out to the first conveyance path 321a.

  The document sheet sent to the first conveyance path 321a in step S21 is conveyed by the conveyance roller pair 327 through the second conveyance path 321b, and when the leading end passes the location of the CIS timing switch PD4, the CIS timing switch PD4 is Turns on (step S23). When the trailing edge of the original sheet passes the location of the CIS timing switch PD4, the CIS timing switch PD4 is turned off (step S24).

  The paper feed controller 501 determines whether the set switch PD1 is on (step S25). If the next document sheet is placed on the document feed tray 31, the set switch PD1 is turned on. If the next document sheet is not placed, the set switch PD1 is turned off.

  When the paper feed controller 501 determines that the set switch PD1 is on (Yes in step S25), the counter 503 is turned on in order to turn on the paper feed motor 340 and control the operation time of the paper feed motor 340. Then, counting of pulses for operating the paper feed motor 340 is started (step S26). When the paper feed motor 340 operates, the next document sheet placed on the document feed tray 31 is sent out to the first transport path 321a by the sending means 331. Then, the process returns to step S22. On the other hand, the previous document sheet is transported along the transport path 321 by the transport roller pair 327, 328, 329 and the discharge roller pair 330, and is discharged to the document discharge tray 33 (step S27).

  When the paper feed controller 501 determines that the set switch PD1 is not turned on (No in step S25), the original sheet on the transport path 321 is transported by the transport roller pairs 327, 328, 329 and the discharge roller pair 330. Then, it is discharged to the document discharge tray 33 (step S28). Then, the paper feed control unit 501. The paper discharge motor 343, the transport motor 342, and the registration motor 341 are turned off (step S29). As a result, the rotations of the transport roller pairs 327, 328, and 329, the paper discharge roller pair 330, and the registration roller pair 326 are stopped.

  The main effects of this embodiment will be described.

  In the present embodiment, when a plurality of document sheets of A5 size or larger that can be detected by the feed switch PD3 are continuously sent from the document feed tray 31 to the transport path 321 (in the first mode), the transport path 321 is transported. The next document sheet is sent out from the document feed tray 31 to the conveyance path 321 on condition that the trailing edge of the document sheet to be detected is detected by the feed switch PD3. On the other hand, when a document sheet smaller than A5 size that cannot be detected by the feed switch PD3 is fed with its long side in the transport direction (in the second mode), the document sheet transported through the transport path 321 On the condition that the trailing edge is detected by the CIS timing switch PD4, the next document sheet is sent out from the document feed tray 31 to the conveyance path 321. As described above, according to the present embodiment, when the feed switch PD3 is arranged side by side with the separation mechanism 325 in order to reduce the document sheet interval, the CIS timing switch PD4 is used for a sheet whose size cannot be detected by the feed switch PD3. The next document sheet is sent out on the condition that it is detected. Accordingly, a plurality of original sheets of A5 size or larger can be continuously sent out to the conveyance path 321 with the original sheet interval shortened, and an original sheet smaller than A5 size is fed with its long side in the conveyance direction. Even when paper is used, it can be continuously sent out to the conveyance path 321. As a result, in the present embodiment, for an A5 size or larger document that is often read by the automatic document feeder 3, the first document sheet starts to be fed after the first document sheet is fed. The time until paper feeding is completed can be shortened. Further, even original sheets smaller than A5 size that are not often read by the automatic document feeder 3 can be read continuously.

  Further, according to the present embodiment, in the second mode, the long side direction of the original sheet of the sheet conveyed through the conveyance path 321 is the conveyance direction. Accordingly, since the original sheet smaller than the A5 size has the long side direction of the original sheet as the transport direction, the original sheet can be transported without increasing the number of transport roller pairs.

  Further, according to the present embodiment, the CIS timing switch PD4 is used as the second detection means when the original sheet smaller than the A5 size is set to have its long side in the transport direction. For this reason, when a document sheet smaller than A5 size has its long side in the transport direction, there is no need to newly provide a second detection means for detecting the document sheet.

  Further, according to the present embodiment, since the CIS is arranged upstream from the image reading position 351, the CIS timing switch PD4 is moved to the transport path 321 compared to the case where the CIS is arranged downstream from the image reading position 351. It can arrange | position in the upstream. Therefore, compared to the case where the CIS is arranged downstream of the image reading position 351, when the long side of the original sheet smaller than A5 size is set in the transport direction, the distance between the original sheets is reduced to the transport path 321. It can be sent out.

  According to the present embodiment, in the second mode, since the document sheet cannot be detected by the feed switch PD3, the document sheet is sent downstream of the conveyance path 321 without correcting the inclination of the document sheet by the registration roller pair 326. If the registration roller pair 326 is rotated after the operation of the sending means 331, the document sheet may be stopped by the registration roller pair 326 and the document sheet may be jammed in the conveyance path 321. In this embodiment, since the registration roller pair 326 is rotated simultaneously with the operation of the feeding unit 331, it is possible to prevent the document sheet from being jammed by the registration roller pair 326. Even if the registration roller pair 326 is rotated faster than the operation of the sending means 331, the document sheet can be prevented from being jammed by the registration roller pair 326.

  A modification of this embodiment will be described. In the present embodiment, in the second mode, on the condition that the trailing edge of the document sheet conveyed on the conveyance path 321 is detected by the CIS timing switch PD4, the sending unit 331 is controlled to control the next document sheet. The document is fed from the document feed tray 31 to the conveyance path 321. In the modification, in the second mode, the sheet feed control unit 501 controls the sending unit 331 to perform the next operation on condition that the leading edge of the document sheet conveyed on the conveyance path 321 is detected by the CIS timing switch PD4. The original document sheet is sent out from the document feed tray 31 to the conveyance path 321. According to the modification, the document sheet interval can be shortened as compared with the present embodiment.

  In the present embodiment, optical sensors are used as the first detection means (feed switch PD3) and the second detection means (CIS timing switch PD4). However, mechanical switches can also be used as the first and second detection means. FIG. 10 is a schematic diagram showing the operation of an example of a mechanical switch that can be used as the first and second detection means.

  The mechanical switch includes a rotating piece 370 disposed in the conveyance path 321. The rotating piece 370 has a fan-shaped surface 372 that faces the conveyance direction of the document sheet D. The rotating piece 370 is rotatable about a shaft 371 provided on the upstream side of the conveyance path 321. The rotating piece 370 is urged by a spring (not shown) in a direction that rotates in a direction protruding on the conveyance path 321.

  As shown in FIG. 10A, before the original sheet D conveyed on the conveyance path 321 hits the fan-shaped surface 372 of the rotation piece 370, the rotation piece 370 is attached to the conveyance path 321. As shown in FIG. 10B, when the document sheet D conveyed on the conveyance path 321 hits the fan-shaped surface 372 of the rotation piece 370, the rotation piece 370 is positioned below the conveyance path 321 about the shaft 371. The document sheet D passes through the rotating piece 370 by rotating (the rotating piece 370 does not protrude into the conveyance path 321). Then, as shown in FIG. 10C, when the original sheet D finishes passing over the rotating piece 370, the rotating piece 370 rotates around the shaft 371 and moves upward. Protrudes on the road 321.

  The mechanical switch is turned off when the rotating piece 370 protrudes on the conveying path 321 ((A) and (C) in FIG. 10), and turned on when the rotating piece 370 does not protrude on the conveying path 321. ((B) of FIG. 10). You may use the above mechanical switches as a 1st detection means and a 2nd detection means.

  In this embodiment, the example in which the sheet feeding device is applied to the automatic document feeding device 3 has been described. However, the sheet feeding apparatus according to the present invention can also be used as an apparatus that conveys a sheet for forming an image to the image forming unit 93 (FIG. 3).

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 3 Automatic document feeder 5 Image reading part 31 Document feed tray (an example of a tray)
321 Conveying path 325 Separation mechanism 326 Registration roller pair (an example of registration roller)
331 Delivery means 341 Registration motor (an example of registration driving means)
350 CIS (an example of a contact-type image sensor)
351 Image reading position 501 Paper feed controller PD3 Feed switch (an example of first detection means)
PD4 CIS timing switch (example of second detection means)

Claims (5)

A tray on which sheets to be fed are placed;
A transport path;
In the case where a plurality of sheets are stacked and placed on the tray, the tray includes a separation mechanism that separates the uppermost sheet from the lower sheet, and sends the sheet placed on the tray to the conveyance path. A delivery means;
A first detection unit that is arranged side by side with the separation mechanism in a direction intersecting with the conveyance direction of the sheet conveyed on the conveyance path, and is capable of detecting a sheet having a predetermined size or more among the sheets conveyed on the conveyance path. When,
A second detection means provided at a position where the sheet smaller than the predetermined size that cannot be detected by the first detection means can be detected, provided downstream of the separation path from the separation mechanism;
A first mode in which a plurality of sheets having a predetermined size or more are continuously sent from the tray to the conveyance path; and a plurality of sheets having a size smaller than the predetermined size are continuously sent from the tray. A paper feed control unit that executes a second mode of sending to the transport path,
In the first mode, the sheet feeding control unit supplies the next sheet to the feeding unit on condition that the trailing edge of the sheet conveyed on the conveyance path is detected by the first detection unit. In the case of the second mode, the next sheet is fed to the feeding means on the condition that the second conveying means detects the sheet conveyed in the conveying path in the second mode. Letting out from the tray to the transport path ,
further,
A registration roller disposed in the transport path downstream from the separation mechanism and upstream from the second detection means;
Controlled by the paper feed control unit, and a registration driving means for rotating the registration roller,
In the first mode, the sheet feeding control unit controls the feeding unit to feed the sheet placed on the tray to the conveyance path, and corrects the inclination of the sheet by the registration roller. The registration driving means is controlled to rotate the registration roller to convey the sheet downstream of the conveyance path. In the second mode, the sheet feeding means is controlled and placed on the tray. A sheet feeding device that controls the registration driving unit to rotate the registration roller at the same time as or earlier than the start of the operation of feeding the sheet to the conveyance path to rotate the registration roller to convey the sheet downstream of the conveyance path .   2. The sheet feeding device according to claim 1, wherein, in the second mode, a sheet conveyed along the conveyance path has a long side direction of the sheet set as a conveyance direction. The conveyance path is a conveyance path that passes through an image reading position where an image of one surface of a conveyed sheet is optically read,
A contact-type imaging device that is disposed in the conveyance path upstream from the image reading position and downstream from the second detection unit, and that reads an image of the other surface of the sheet conveyed through the conveyance path;
3. The sheet feeding device according to claim 1, wherein the second detection unit is used to detect timing when reading an image on the other surface of the sheet conveyed on the conveyance path by the imaging element. In the second mode, the sheet feeding control unit controls the feeding unit on the condition that the leading end of the sheet conveyed on the conveyance path is detected by the second detecting unit, and performs the following sheet feeding apparatus according to any one of claim 1 to 3 for fed sheets from the tray to the transporting path. A sheet feeding device according to any one of claims 1 to 4 ,
An image reading unit for reading an image of a sheet fed from the sheet feeding device;
An image forming apparatus comprising: an apparatus main body that forms and outputs an image read by the image reading unit on a sheet.

Images