WO2024019750A1

WO2024019750A1 - Shutter structure for sheet feeding apparatus

Info

Publication number: WO2024019750A1
Application number: PCT/US2022/053475
Authority: WO
Inventors: Yeontaek Jeong; Jaewuk LEE; Sangcheol Kim; Jungkyu PARK; Taewon Eom
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2022-07-18
Filing date: 2022-12-20
Publication date: 2024-01-25
Also published as: KR20240011000A

Abstract

A sheet feeding apparatus includes a forward roller (10) to feed a sheet, a separating member (20) engaged with the forward roller to form a separating nip (30), a shutter (80) movable between an aligning position on an upstream side of the separating nip to align a front end of the sheet before the front end of the sheet enters the separating nip and a feeding position to allow feeding of the sheet, and an elastic member (90) to apply an elastic force to the shutter in a direction to return the shutter to the aligning position.

Description

SHUTTER STRUCTURE FOR SHEET FEEDING APPARATUS BACKGROUND [0001] An apparatus using sheet media includes a sheet feeding apparatus that separates and feeds a sheet medium one by one from a plurality of sheet media loaded on a loading tray. The sheet feeding apparatus may include a separating portion that separates one sheet from among a plurality of sheets by using a frictional force scheme. The sheet feeding apparatus may be applied to various apparatuses such as a scanner, an image forming apparatus, etc. The scanner includes a tray on which a plurality of documents are loaded, and a document feeding apparatus that draws out documents one by one from the tray and feeds the same to a reading member. The image forming apparatus includes a loading tray on which a plurality of print media are loaded, e.g., a sheet feeding cassette, and a print medium feeding apparatus that draws out the print media one by one from the sheeting feeding cassette and feeds the same to a printing unit. BRIEF DESCRIPTION OF THE DRAWINGS [0002] FIG.1 is a schematic structural diagram of an example of a sheet feeding apparatus. [0003] FIG. 2 is a partial exploded perspective view of an example of a sheet feeding apparatus. [0004] FIG.3 is a detailed diagram of an example of an aligning portion. [0005] FIG.4 shows an example of a form where a plurality of sheets are multi- stage loaded on a loading table. [0006] FIG.5 shows an example of an effect of a shutter. [0007] FIG.6 shows an example where some of a plurality of sheets are loaded in a reverse wedge form on a loading table. [0008] FIG.7 shows an effect of a shutter. [0009] FIG.8 shows an example of a separation operation in a case where one sheet enters a separating nip. [0010] FIG.9 shows an example of a separation operation in a case where two sheets enter a separating nip. [0011] FIG.10 is a schematic structural diagram of an example of a sheet feeding apparatus. [0012] FIG.11 is a schematic structural diagram of an example of a scanner. [0013] FIG. 12 is a schematic structural diagram of an example of an image forming apparatus. DETAILED DESCRIPTION [0014] A sheet may refer to a medium in a form of a cut-sheet having a specific size. Depending on an apparatus employing a sheet feeding apparatus, a sheet may be referred to as various names. For example, in a scanner, a sheet may be referred to as a document. For instance, in an image forming apparatus, the sheet may be referred to as a print medium. A plurality of sheets may be loaded on a loading means (or loading table), e.g., a tray, a sheet feeding cassette, etc., and the sheet feeding apparatus may separate one sheet from among the plurality of sheets loaded on the loading means (loading table) and feed the same. [0015] The sheet feeding apparatus may include a separating portion that separates the sheets one by one from the plurality of sheets. The separating portion may separate one sheet from the plurality of sheets and feed the same by using differences in frictional force between sheets, between a sheet and a feed roller, and between a sheet and a separating member. The separation performance of the separating portion may be affected by the frictional force between sheets, a state of a sheet fed to the separating portion for separating the sheets, etc. For example, when sheets are loaded on the loading means (loading table) several times in a divided manner, the sheets on the loading means (loading table) may be divided into a plurality of sheet stacks. This type of loading is referred to as multi-stage loading. In case of multi-stage loading, frictional forces between the plurality of sheet stacks are reduced, such that a sheet stack located on top may be fed to the separating portion at a time. In this case, the probability of double feeding occurring in the separating portion may increase. In a case where a plurality of sheets to be fed to the separating portion are fed in the reverse wedge form, the probability of double feeding occurring in the separating portion may increase. The reverse wedge form refers to a form in which a sheet located lower than a sheet on top is fed to the separating portion earlier than the sheet on top in a case where the plurality of sheets are fed to the separating portion. [0016] The sheet feeding apparatus according to the disclosure employs a structure capable of reducing the probability of double feeding. The probability of double feeding may be reduced by aligning front ends of the plurality of sheets in a wedge form before the plurality of sheets enter a separating nip. The sheet feeding apparatus according to an example of the disclosure may include a shutter capable of moving between an aligning position located on an upstream side of the separating nip to align the front ends of the sheets before the front ends of the sheets enter the separating nip and a feeding position to allow feeding of the sheets. By aligning front ends of a plurality of sheets in the wedge form before the front ends of the plurality of sheets enter the separating nip by using the shutter, the probability of double feeding occurring due to multistage loading of the plurality of sheets or the plurality of sheets in the reverse wedge form may be reduced. [0017] The shutter may be elastically biased in a direction to return to the aligning position from the feeding position by an elastic member. The sheet loaded on a loading means (loading table) may be fed to the separating nip by the pickup roller. The shutter may be moved to the feeding position from the aligning position by being pushed by the front end of the sheet fed to the separating nip. A forward roller feeding the sheet and the separating member may form the separating nip by being engaged with each other. The shutter may be supported to rotate around a rotation shaft of the forward roller to the aligning position and the feeding position. The shutter may include an aligning portion with which the front ends of the sheets are aligned in contact. The aligning portion may have a shape capable of aligning the front ends of the plurality of sheets in the wedge form. For example, the aligning portion may be inclined in a direction opposite to a sheet feeding direction with respect to a reference line that passes through the center of the forward roller and passes through the center of the separating nip. The shutter may include a pair of aligning portions located on opposite sides of the forward roller in a longitudinal direction to align the front ends of the sheets. A stopper may block the shutter from moving, e.g., rotating beyond the aligning position in spite of an elastic force of the elastic member. The separating member may include a frictional pad that elastically contacts the forward roller to form the separating nip. The separating member may include a separating roller engaged with the forward roller to form the separating nip. A torque limiter may selectively allow driven rotation of the separating roller by the forward roller, based on a magnitude of torque applied to the separating roller. [0018] The above-described sheet feeding apparatus may be applied to the document feeding apparatus of the scanner. The above-described sheet feeding apparatus may be applied to a print medium feeding apparatus of the image forming apparatus. Hereinbelow, examples of a sheet feeding apparatus, a scanner, an image forming apparatus will be described with reference to the drawings. Components having substantially the same functional configurations in the present specification and drawings will be referred to as the same reference numerals to omit redundant description. [0019] FIG.1 is a schematic structural diagram of an example of a sheet feeding apparatus. Referring to FIG.1, a sheet feeding apparatus may include a forward roller 10 that feeds sheets S, a separating member 20 that is engaged with the forward roller 10 to form a separating nip 30, and a shutter 80. The shutter 80 may be moved between an aligning position (a solid line of FIG.1) located on an upstream side of the separating nip 30 to align front ends of the sheets S before the front ends of the sheets S enter the separating nip 30 and a feeding position (a dotted line of FIG.1) to allow feeding of the sheets S. The shutter 80 may align the front ends of the plurality of sheets S in the wedge form in the aligning position. The 'upstream side' has a relative meaning with respect to a feeding direction of the sheets S to the separating nip 30, e.g., a forward direction FD. Thus, the 'upstream side of the separating nip 30' means a side in a reverse direction RD of the separating nip 30. For example, in FIG. 1, the 'upstream side of the separating nip 30' may be a left side of the separating nip 30 and an inlet side of the separating nip 30. The 'wedge form' means that the front ends of the plurality of sheets S before entering the separating nip 30 have a form pointed toward the forward roller 10. Thus, the 'reverse wedge form' means that the front ends of the plurality of sheets S before entering the separating nip 30 have a form pointed toward the separating roller 20. [0020] The plurality of sheets S may be loaded on a loading table 50. The pickup roller 40 may feed the plurality of sheets S loaded on the loading table 50 to the separating nip 30. The pickup roller 40 may contact a sheet S1 located on top among the plurality of sheets S on the loading table 50. Although not shown, the pickup roller 40 may be moved to a pickup position contacting the sheet S1 located on top and to a standby position separated from the sheet S1 located on top. For example, the pickup roller 40 may rotate around a rotation shaft 11 of the forward roller 10 to be moved to the pickup position and the standby position. Although not shown, as the number of sheets S loaded on the loading table 50 decreases, the loading table 50 may be moved toward the pickup roller 40. [0021] The forward roller 10 may feed the sheets S. The forward roller 10 may feed the sheets S in the forward direction FD. The forward roller 10 may be installed on the rotation shaft 11 and may rotate together with the rotation shaft 11 to feed the sheets S entering the separating nip 30 in the forward direction FD. The separating member 20 may be engaged with the forward roller 10 to form the separating nip 30. In the current example, a separating member of a roller type may be employed. Hereinbelow, the separating member 20 will referred to as the separating roller 20. The separating roller 20 may be elastically biased by an elastic member (not shown) in a direction contacting the forward roller 10. The separating roller 20 may be supported to rotate on a support shaft 21. The separating roller 20 may be a driven roller to which a driving force is not delivered. A torque limiter 22 may be arranged between the separating roller 20 and the support shaft 21. The torque limiter 22 may selectively allow driven rotation of the separating roller 20 by the forward roller 10, based on a magnitude of torque applied to the separating roller 20. [0022] The pickup roller 40, the forward roller 10, and the separating roller 20 may be supported by a frame 60. For example, the rotation shaft 41 of the pickup roller 40, the rotation shaft 11 of the forward roller 10, and the support shaft 21 of the separating roller 20 may be supported by the frame 60. [0023] The shutter 80 may be moved to the aligning position and the feeding position. The shutter 80 may be rotated to the aligning position and the feeding position. FIG.2 is a partial exploded perspective view of an example of a sheet feeding apparatus. Referring to FIGS.1 and 2, the shutter 80 may be supported on the rotation shaft 11 of the forward roller 10 so as to be rotated to the aligning position and the feeding position. An elastic member 90 may apply an elastic force to the shutter 80 in a direction returned from the feeding position to the aligning position. For example, the elastic member 90 may be implemented as a torsion coil spring having an end portion supported by the shutter 80 and the other end portion supported by the frame 60. The form of the elastic member 90 is not limited thereto, and the elastic member 90 may be implemented as a spring in various forms capable of applying an elastic force to the shutter 80 in a direction to return to the aligning position. A stopper 63 may block the shutter 80 from moving, e.g., rotating, beyond the aligning position. For example, the shutter 80 may include an interfering portion 82. In the frame 60, a groove 62 into which the interfering portion 82 is inserted may be provided. The stopper 63 may be implemented by an end portion of the groove 62. As the interfering portion 82 of the shutter 80 is locked by the stopper 63 at the aligning position, the shutter 80 may be maintained at the aligning position. [0024] The shutter 80 may include an aligning portion 81 with which front ends of the sheets S are aligned in contact. For example, the shutter 80 may include a pair of aligning portions 81 located on opposite sides of the forward roller 10 in a longitudinal direction. The pair of aligning portions 81 may be connected to each other by, for example, the interfering portion 82 extending in the longitudinal direction. By using the pair of aligning portions 81 separated in the longitudinal direction, i.e., a width direction of the sheets S, the front ends of the sheets S may be stably aligned. Once the shutter 80 is located at the aligning position, the aligning portion 81 may be located on the upstream side of the separating nip 30. In a case where the front ends of the sheets S fed in the forward direction FD by the pickup roller 40 pushes the aligning portion 81, the shutter 80 may be rotated to the feeding position from the aligning position. As the shutter 80 is rotated to the feeding position, the interfering portion 82 may be separated from the stopper 63. After the sheets S pass through the separating nip 30, interference between the sheets S and the shutter 80 may be terminated. The shutter 80 may be returned to the aligning position by the elastic force of the elastic member 90, and the interfering portion 82 contacts the stopper 63, thus maintaining the shutter 80 at the aligning position. [0025] FIG. 3 is a detailed diagram of an example of the aligning portion 81. Referring to FIG. 3, the shutter 80 may be located at the aligning position. The aligning portion 81 may be located on the upstream side of the separating nip 30. The aligning portion 81 may be inclined with respect to a reference line RL passing through the center of the forward roller 10 and the center of the separating nip 30 in a direction opposite to the feeding direction of the sheets S (the forward direction FD), i.e., in a reverse direction RD. The reference line RL may be a line connecting, for example, the center of the forward roller 10 to the center of the separating roller 20. For example, the aligning portion 81 may have an angle AG with respect to the reference line RL in the reverse direction RD. The angle AG may be appropriately determined to align the front ends of the plurality of sheets S contacting the aligning portion 81 in the wedge form. With this structure, the front ends of the plurality of sheets S may be aligned in the wedge form before entering the separating nip 30. [0026] A form in which the sheets S are loaded on the loading table 50 may be various. For example, new sheets S may be additionally loaded before the previously loaded sheets S are used up. Such additional loading may be performed twice or more. FIG.4 shows an example of a form where the plurality of sheets S are multi-stage loaded on the loading table 50. FIG. 5 shows an example of an effect of the shutter 80. Referring to FIG.4, the plurality of sheets S may be loaded as a first stage ST1, a second stage ST2, and a third stage ST3. Such a loading form may appear such that the second stage ST2 is loaded in a state where the first stage ST1 is loaded, and then the third stage ST3 is loaded on the second stage ST2. In this case, sheets forming the first stage ST1, sheets forming the second stage ST2, and sheets forming the third stage ST3 may have different physical properties. In this case, a frictional force between the first stage ST1 and the second stage ST2 and a frictional force between the second stage ST2 and the third stage ST3 may be different from each other. The frictional force between the first stage ST1 and the second stage ST2 and the frictional force between the second stage ST2 and the third stage ST3 may be less than a frictional force between sheets of the first stage ST1, the second stage ST2 and the third stage ST3. This is because, during multi-stage loading, air layers are arranged between the first stage ST1 and the second stage ST2 and between the second stage ST2 and the third stage ST3, reducing a frictional coefficient between stages. [0027] In such a loading form, upon rotation of the pickup roller 40, the third stage ST3 may be fed at a time or the plurality of sheets S of the third stage ST3 may be fed, in the forward direction FD. Then, the plurality of sheets S forming the third stage ST3 may enter the separating nip 30, such that a separation operation may not be properly performed and double feeding may occur. This is because in a case where a sheet located at the bottom among the plurality of sheets S first enters the separating nip 30, the separating roller 20 is not driven by the forward roller 10 and thus is stopped without being rotated, such that the other sheets than the sheet located at the bottom among the plurality of sheets S pass through the separating nip 30 at a time. [0028] According to the sheet feeding apparatus in the current example, the shutter 80 is located at the aligning position. The aligning portion 81 may be located on the upstream side of the separating nip 30. The front ends of the plurality of sheets S forming the third stage ST3 contact the aligning portion 81 before entering the separating nip 30. The shutter 80 may be maintained at the aligning position by the elastic force of the elastic member 90. The aligning portion 81 may be inclined with respect to the reference line RL in the reverse direction RD. Thus, in a case where the front ends of the plurality of sheets S forming the third stage ST3 contact the aligning portion 81, they are aligned in the wedge form as shown in FIG.5. In this state, as the pickup roller 40 continues being rotated, the shutter 80 may be rotated to the feeding position by being pushed by the front ends of the plurality of sheets S. The plurality of sheets S may be fed to the separating nip 30 in a state of the front ends thereof being aligned in the wedge form. In this case, the sheet S1 located on top may enter the separating nip 30 first. In a case where a sheet S2 located immediately under the sheet S1 located on top enters the separating nip 30, the separating roller 20 may not be driven by the forward roller 10 and thus may be stopped without being rotated. Thus, the sheet S1 located on top may be separated and pass through the separating nip 30. [0029] FIG. 6 shows an example where some of the plurality of sheets S are loaded in the reverse wedge form on the loading table 50. FIG.7 shows an effect of the shutter 80. Referring to FIG. 6, a plurality of sheets S1, S2, S3, and S4 close to the pickup roller 40 among the plurality of sheets S may be loaded in the reverse wedge form as indicated by reference numeral 70. Such a loading form may occur in a process of loading the plurality of sheets S on the loading table 50 and in a process of drawing out the sheets S from the loading table 50. Upon rotation of the pickup roller 40 in such a loading form, for example, the plurality of sheets S1, S2, S3, and S4 may be fed toward the separating nip 30 at a time. In a case where the plurality of sheets S1, S2, S3, and S4 enter the separating nip 30 while maintaining the reverse wedge form, the sheet S4 may enter the separating nip 30 first. Then, the separating roller 20 is not driven by the forward roller 10 and thus is stopped without being rotated, such that the sheets S1, S2, and S3 except for the sheet S4 pass through the separating nip 30 at a time, causing double feeding. [0030] According to the sheet feeding apparatus in the current example, the shutter 80 is located at the aligning position. The aligning portion 81 may be located on the upstream side of the separating nip 30. The front end of the sheet S4 among the plurality of sheets S1, S2, S3, and S4 contacts the aligning portion 81 first. The shutter 80 may be maintained at the aligning position by the elastic force of the elastic member 90. Next, the sheets S3, S2, and S1 sequentially contact the aligning portion 81. The aligning portion 81 may be inclined with respect to the reference line RL in the reverse direction RD. Thus, the front ends of the plurality of sheets S1, S2, S3, and S4 may be aligned in the wedge form as shown in FIG.7. While it is shown in FIG.7 that the front ends of the sheets S1 and S2 are in contact with the aligning portion 81, the front ends of the sheets S1, S2, S3, and S4 may be aligned in contact with the aligning portion 81 in the wedge form. In this state, as the pickup roller 40 continues being rotating, the shutter 80 may be rotated to the feeding position by being pushed by the front ends of the plurality of sheets S1, S2, S3, and S4. The plurality of sheets S1, S2, S3, and S4 may be fed to the separating nip 30 in a state of the front ends thereof being aligned in the wedge form. In this case, the sheet S1 located on top may enter the separating nip 30 first. In a case where the sheet S2 located immediately under the sheet S1 located on top enters the separating nip 30, the separating roller 20 may not be driven by the forward roller 10 and thus may be stopped without being rotated. Thus, the sheet S1 located on top may be separated and pass through the separating nip 30. [0031] The separation operation performed in the separating nip 30 will be briefly described below. For example, in a case where the magnitude of the torque applied to the separating roller 20 is greater than a threshold torque of the torque limiter 22, the separating roller 20 may be rotated with respect to the support shaft 21. This condition may be implemented in a case where there is no sheet S in the separating nip 30 or one sheet S enters the separating nip 30. FIG.8 shows an example of a separation operation in a case where one sheet S1 enters the separating nip 30. For example, the front end of the sheet S1 picked up from the loading table 50 by the pickup roller 40 and fed to the separating nip 30 may contact the aligning portion 81. The aligning portion 81 may be maintained at the aligning position by the elastic force of the elastic member 90. In a case where a feeding force of the sheet S1 in the forward direction FD is greater than the elastic force of the elastic member 90, the shutter 80 may be rotated toward the feeding position by being pushed by the front end of the sheet S1. The sheet S1 may enter the separating nip 30. The torque applied to the separating roller 20 by the sheet S1 fed in the forward direction FD by the forward roller 10 may be greater than the threshold torque of the torque limiter 22. The separating roller 20 may be rotated with respect to the support shaft 21. As the separating roller 20 is rotated by being driven by the forward roller 10, the separating roller 20 may feed the sheet S1 in the forward direction FD. In a case where the rear end of the sheet S1 passes through the separating nip 30, contact between the aligning portion 81 and the sheet S1 may be terminated, and the shutter 80 may be returned to the aligning position by the elastic force of the elastic member 90, and may be maintained at the aligning position as the interfering portion 82 contacts the stopper 63. [0032] For example, in a case where the magnitude of the torque applied to the separating roller 20 is less than the threshold torque of the torque limiter 22, the separating roller 20 may not be rotated. This condition may be implemented in a case where two or more sheets S enter the separating nip 30. FIG.9 shows an example of a separation operation in a case where the two or more sheets S1 and S2 enter the separating nip 30. For example, in a case where the two sheets S1 and S2 enter the separating nip 30, the sheet S1 located upper than the other between the two sheets S1 and S2 may contact the forward roller 10 and the sheet S2 located lower than the other may contact the separating roller 20. A frictional force between the two sheets S1 and S2 may be much less than a frictional force between the sheet S1 located upper and the forward roller 10 and a frictional force between the sheet S2 located lower and the separating roller 20. The torque applied to the separating roller 20 by the frictional force between the two sheets S1 and S2 may be less than the threshold torque of the torque limiter 22. The separating roller 20 may not be rotated. The sheet S1 located upper may be fed by the forward roller 10 in the forward direction FD, and the sheet S2 located lower may not be fed by being blocked by the separating roller 20. In a case where the rear end of the sheet S1 passes through the separating nip 30, contact between the aligning portion 81 and the sheet S1 may be terminated, and the shutter 80 may be returned to the aligning position by the elastic force of the elastic member 90, and may be maintained at the aligning position as the interfering portion 82 contacts the stopper 63. [0033] Although not shown, a driving force in a direction to feed a sheet in the reverse direction RD may be applied to the separating roller 20. The driving force may be delivered through the torque limiter 22. In a case where one sheet S1 enters the separating nip 30, the torque applied to the separating roller 20 by the sheet S fed in the forward direction FD by the forward roller 10 may be greater than the threshold torque of the torque limiter 22. Thus, the separating roller 20 may be driven by the forward roller 10 and thus rotated in a direction to feed the sheet S1 in the forward direction FD. In a case where the two sheets S1 and S2 enter the separating nip 30, the torque applied to the separating roller 20 by the frictional force between the two sheets S1 and S2 may be less than the threshold torque of the torque limiter 22. The separating roller 20 may be rotated by the driving force to feed the sheet S2 in the reverse direction RD and may feed the sheet S2 located lower in the reverse direction RD. In a case where the front end of the sheet S2 located lower leaves the separating nip 30, the separating roller 20 may be driven by the forward roller 10 so as to be rotated in a direction to feed the sheet S1 in the forward direction FD. [0034] FIG.10 is a schematic structural diagram of an example of a sheet feeding apparatus. The sheet feeding apparatus of the current example may be different from the sheet feeding apparatus shown in FIGS.1 to 9 in a sense that a frictional pad 20a is applied as the separating member, in place of the separating roller 20. A difference will be mainly described below. Referring to FIG.10, the separating member may include the frictional pad 20a. The frictional pad 20a may elastically contact the forward roller 10a to form a separating nip 30a. The elastic member 29 may apply an elastic force to the frictional pad 20a in a direction to contact the forward roller 10a. For example, the frictional pad 20a may be supported by an elevating member 28, and the elastic member 29 may apply the above-described elastic force to the elevating member 28. The sheet S may be supported by the loading table 50. The forward roller 10a may contact the sheet S loaded on the loading table 50. In the sheet feeding apparatus shown in FIG. 10, the forward roller 10a may simultaneously have a function of feeding the sheet S loaded on the loading table 50 and a function of forming the separating nip 30a together with the frictional pad 20a. That is, the forward roller 10a may perform functions of the pickup roller 40 and the forward roller 10 in the example of the sheet feeding apparatus shown in FIGS.1 to 9. Although not shown, a pickup roller feeding the sheet S loaded on the loading table 50 to the separating nip 30a may be provided. In FIG.10, the elastic member 90 and the frame 60 are omitted. [0035] The shutter 80 may be the same as described above with reference to FIGS. 1 to 9. In this case, the reference line RL may be a line connecting the center of the forward roller 10a to the center of the separating nip 30a. The aligning portion 81 may have a shape inclined with respect to the reference line RL in a direction opposite to the feeding direction of the sheets S when the shutter 80 is located at the aligning position. For example, the aligning portion 81 may have the angle AG with respect to the reference line RL. The angle AG may be appropriately determined to align the front ends of the plurality of sheets S contacting the aligning portion 81 in the wedge form. [0036] A separation operation performed in the separating nip 30a in the example of the sheet feeding apparatus shown in FIG.10 will be briefly described below. For example, the front end of one sheet S1 picked up from the loading table 50 by the forward roller 10a and fed to the separating nip 30a may contact the aligning portion 81. The aligning portion 81 may be maintained at the aligning position by the elastic force of the elastic member 90. In a case where a feeding force of the sheet S1 in the forward direction FD is greater than the elastic force of the elastic member 90, the shutter 80 may be rotated toward the feeding position by being pushed by the front end of the sheet S1. The sheet S1 may enter the separating nip 30a. A frictional force between the forward roller 10a and the sheet S1 may be greater than a frictional force between the sheet S1 and the frictional pad 20a. Thus, as the forward roller 10a is rotated, the sheet S1 may be fed in the forward direction FD. In a case where the rear end of the sheet S1 passes through the separating nip 30, contact between the aligning portion 81 and the sheet S1 may be terminated, and the shutter 80 may be returned to the aligning position by the elastic force of the elastic member 90, and may be maintained at the aligning position as the interfering portion 82 contacts the stopper 63. [0037] For example, the two sheets S1 and S2 may be picked up from the loading table 50 by the forward roller 10a and fed to the separating nip 30a. The front ends of the sheets S1 and S2 may contact the aligning portion 81 and may be aligned in the wedge form. In a case where the feeding forces of the sheets S1 and S2 in the forward direction FD is greater than the elastic force of the elastic member 90, the shutter 80 may be rotated toward the feeding position by being pushed by the front end of the sheet S1. In a case where the two sheets S1 and S2 enter the separating nip 30a, the sheet S1 located upper than the other between the two sheets S1 and S2 may contact the forward roller 10a in the separating nip 30a and the sheet S2 located lower than the other may contact the frictional pad 20a. A frictional force between the two sheets S1 and S2 may be much less than a frictional force between the sheet S1 located upper and the forward roller 10 and a frictional force between the sheet S2 located lower and the separating roller 20. A slip may occur between the two sheets S1 and S2, and as the forward roller 10a is rotated, the sheet S1 is fed in the forward direction FD and the sheet S2 is not fed. In a case where the rear end of the sheet S1 passes through the separating nip 30a, contact between the aligning portion 81 and the sheet S1 may be terminated, and the shutter 80 may be returned to the aligning position by the elastic force of the elastic member 90, and may be maintained at the aligning position as the interfering portion 82 contacts the stopper 63. [0038] The above-described sheet feeding apparatus may be applied to the scanner. FIG.11 is a schematic structural diagram of an example of a scanner 1. Referring to FIG.11, the scanner 1 may include a document feeding apparatus 100 that feeds a document D, and a reading member 205 that reads an image from the document D. As the document feeding apparatus 100, the sheet feeding apparatus described with reference to FIGS.1 to 10 may be applied. In this case, in the description of FIGS.1 to 10, the sheet S may be regarded as the document D. For example, the document feeding apparatus 100 may include the loading table 50 on which the document D is loaded, the forward roller 10 that feeds the document D, the separating member 20 that is engaged with the forward roller 10 to form the separating nip 30, the pickup roller 40 that feeds the document D on the loading table 50 to the separating nip 30, the shutter 80 capable of being rotated to the aligning position located on the upstream side of the separating nip 30 to align the front end of the document D before the front end of the document D enters the separating nip 30 and the feeding position that allows the document D to be fed by being pushed by the front end of the document D fed by the pickup roller 40, and the elastic member 90 that applies an elastic force to the shutter 80 in a direction to return to the aligning position. [0039] Various examples of the sheet feeding apparatus described with reference to FIGS. 1 to 10 may be applied to the document feeding apparatus 100. For example, the shutter 80 may include the aligning portion 81 with which the front end of the document D is aligned in contact. The aligning portion 81 may be inclined with respect to a reference line RL passing through the center of the forward roller 10 and the center of the separating nip 30 in a direction opposite to the feeding direction of the document D. The separating member may include the separating roller 20 engaged with the forward roller 10 to form the separating nip 30. The torque limiter 22 may be arranged between the separating roller 20 and the support shaft 21. The torque limiter 22 may selectively allow driven rotation of the separating roller 20 by the forward roller 10, based on a magnitude of torque applied to the separating roller 20. [0040] The document feeding apparatus 100 may draw one document D from a plurality of documents D located on the loading table 50 and feed the document D on a document feeding path DP. On the document feeding path DP, a plurality of feed rollers 201, 202, and 203 that feed the document D may be arranged. Each of the plurality of feed rollers 201, 202, and 203 may have a form in which a pair of rollers are engaged with each other. The reading member 25 may be installed on the document feeding path DP to read the image from the document D fed along the document feeding path D. The document D having been read may be discharged to a discharge tray 208 by discharge rollers 206 and 207. Each of the discharge rollers 206 and 207 may have a form in which a pair of rollers are engaged with each other. Although not shown, one or more sensors for sensing the document D may be arranged on the document feeding path DP. [0041] The scanner 1 of the current example is a composite scanner capable of performing flatbed scanning where the document D is at a fixed position and the reading member 205 reads an image while moving in a sub-scanning direction and document feed scanning where an image is read from the document D fed in the sub-scanning direction by using the reading member 205 located at a fixed position. The scanner 1 may include a lower unit 1-2 including platen glass 209 on which a document D for flatbed scanning is placed and an upper unit 1-1 that feeds the document D along the document feeding path DP to perform document feed scanning. The platen glass 209 may be provided on a top surface of the lower unit 1-2, i.e., a face opposing the upper unit 1-1. The upper unit 1-1 may be rotated with respect to the lower unit 1-1 at an open position that opens the top of the platen glass 209 to allow the document D to be placed on the platen glass 209 and a closed position that closes the platen glass 209. The reading member 205 may be arranged, for example, on the lower unit 1-2. The reading member 205 may include a light source that irradiates light to the document D and a photoelectric conversion element that converts an optical signal into an electric signal by receiving and photoelectrically converting light reflected from the document D. A contact type image sensor (CIS), a charge coupled device (CCD), etc., may be used as the reading member 205. The reading member 205 may be a one-dimensional sensor having a length in a main scanning direction. To obtain two-dimensional (2D) image data, in document feed scanning, the document D is moved in a sub-scanning direction along the document feeding path DP and the reading member 205 is at a reading position opposing a reading window 204 to read an image from the document D, thus obtaining the 2D image data. In flatbed scanning, the document D is on the platen glass 209 and the reading member 205 reads the image from the document D while moving in the sub-scanning direction, thus obtaining the 2D image data. [0042] FIG. 12 is a schematic structural diagram of an example of an image forming apparatus. Referring to FIG.12, an image forming apparatus may include a printing unit 2. The printing unit 2 may print an image on the print medium P. The print medium P may be fed to the printing unit 2 from sheet feeders 3 and 4. The printing unit 2 may print the image on the print medium P using various printing methods such as an electrophotographic method, an inkjet method, a thermal transfer method, a thermal sublimation method, etc. For example, the image forming apparatus of the current example may print a color image on the print medium P by using the electrophotographic method. The image forming apparatus may further include the scanner 1. This type of the image forming apparatus may be referred to as a multi-function printer. [0043] The sheet feeder 3 may be a cassette-type sheet feeder. The sheet feeder 3 may include a plurality of sheet feeding cassettes. The sheet feeder 4 may be a multi-purpose sheet feeder capable of feeding the print medium P of various sizes. The sheet feeders 3 and 4 may include a print medium feeding apparatus 200. As the print medium feeding apparatus 200, the sheet feeding apparatus described with reference to FIGS. 1 to 10 may be applied. In this case, in the description of FIGS.1 to 10, the sheet S may be regarded as the print medium P. For example, the print medium feeding apparatus 200 may include the loading table 50 on which the print medium P is loaded, the forward roller 10 that feeds the print medium P, the separating member 20 that is engaged with the forward roller 10 to form the separating nip 30, the pickup roller 40 that feeds the print medium P on the loading table 50 to the separating nip 30, the shutter 80 capable of being rotated to the aligning position located on the upstream side of the separating nip 30 to align the front end of the print medium P before the front end of the print medium P enters the separating nip 30 and the feeding position that allows the print medium P to be fed by being pushed by the front end of the print medium P fed by the pickup roller 40, and the elastic member 90 that applies an elastic force to the shutter 80 in a direction to return to the aligning position. [0044] Various examples of the sheet feeding apparatus described with reference to FIGS.1 to 10 may be applied to the document feeding apparatus 100. Various examples of the sheet feeding apparatus described with reference to FIGS.1 to 10 may be applied to a print medium feeding apparatus 200. For example, the shutter 80 may include the aligning portion 81 with which a front end of the print medium P is aligned in contact. The aligning portion 81 may be inclined with respect to a reference line RL passing through the center of the forward roller 10 and the center of the separating nip 30 in a direction opposite to the feeding direction of the print medium P. The separating member may include the separating roller 20 engaged with the forward roller 10 to form the separating nip 30. The torque limiter 22 may be arranged between the separating roller 20 and the support shaft 21. The torque limiter 22 may selectively allow driven rotation of the separating roller 20 by the forward roller 10, based on a magnitude of torque applied to the separating roller 20. [0045] While examples of the disclosure have been described by the limited examples of the disclosure and drawings, various modifications and changes may be made from the disclosure by those of ordinary skill in the art. For example, even when described techniques are performed in a sequence different from the described method and/or components such as systems, structures, devices, circuits, etc. are combined or connected differently from the described method, or replaced with other components or equivalents, an appropriate result may be achieved. Therefore, the scope of the disclosure should not be determined by the described examples, and should be determined by the claims and equivalents thereto as well as the claims described below.

Claims

WHAT IS CLAIMED IS: 1. A sheet feeding apparatus comprising: a forward roller to feed a sheet; a separating member engaged with the forward roller to form a separating nip; a shutter movable between an aligning position on an upstream side of the separating nip to align a front end of the sheet before the front end of the sheet enters the separating nip and a feeding position to allow feeding of the sheet; and an elastic member to apply an elastic force to the shutter in a direction to return the shutter to the aligning position.

2. The sheet feeding apparatus of claim 1, further comprising a pickup roller to feed the sheet to the separating nip.

3. The sheet feeding apparatus of claim 2, wherein the shutter is moved to the feeding position by being pushed by the front end of the sheet fed by the pickup roller.

4. The sheet feeding apparatus of claim 1, wherein the shutter is supported on a rotation shaft of the forward roller so as to be rotated to the aligning position and to the feeding position.

5. The sheet feeding apparatus of claim 1, wherein the shutter comprises an aligning portion with which the front end of the sheet is aligned in contact, and the aligning portion is inclined in a direction opposite to a feeding direction of the sheet with respect to a reference line that passes through a center of the forward roller and passes through a center of the separating nip.

6. The sheet feeding apparatus of claim 1, wherein the shutter comprises a pair of aligning portions located on both sides of the forward roller in a longitudinal direction and with which the front end of the sheet is aligned in contact with the aligning portions.

7. The sheet feeding apparatus of claim 1, further comprising a stopper to block the shutter from moving beyond the aligning position.

8. The sheet feeding apparatus of claim 1, wherein the separating member comprises a frictional pad to elastically contact the forward roller to form the separating nip.

9. The sheet feeding apparatus of claim 1, wherein the separating member comprises a separating roller engaged with the forward roller to form the separating nip, and the sheet feeding apparatus further comprises a torque limiter to selectively allow driven rotation of the separating roller by the forward roller based on a magnitude of torque applied to the separating roller.

10. A scanner comprising: a loading table on which a document is loaded; a forward roller to feed the document; a separating member engaged with the forward roller to form a separating nip; a pickup roller to feed the document on the loading table to the separating nip; a shutter to be rotatable between an aligning position located on an upstream side of the separating nip to align a front end of the document before the front end of the document enters the separating nip and a feeding position to allow the document to be fed by being pushed by the front end of the document fed by the pickup roller; an elastic member to apply an elastic force to the shutter in a direction to return to the aligning position; and a reading member to read an image from the document.

11. The scanner of claim 10, wherein the shutter comprises an aligning portion with which the front end of the document is aligned in contact with the aligning portion, and the aligning portion is inclined in a direction opposite to a feeding direction of the document with respect to a reference line that passes through a center of the forward roller and passes through a center of the separating nip.

12. The scanner of claim 10, wherein the separating member comprises a separating roller engaged with the forward roller to form the separating nip, and the scanner further comprises a torque limiter to selectively allow driven rotation of the separating roller by the forward roller based on a magnitude of torque applied to the separating roller.

13. An image forming apparatus comprising: a printing unit to print an image on a print medium; a loading table on which the print medium is loaded; a forward roller to feed the print medium; a separating member engaged with the forward roller to form a separating nip; a pickup roller to feed the print medium on the loading table to the separating nip; a shutter to be rotatable between an aligning position located on an upstream side of the separating nip to align a front end of the print medium before the front end of the print medium enters the separating nip and a feeding position to allow the print medium to be fed by being pushed by the front end of the print medium fed by the pickup roller; and an elastic member to apply an elastic force to the shutter in a direction to return to the aligning position.

14. The image forming apparatus of claim 13, wherein the shutter comprises an aligning portion with which the front end of the print medium is aligned in contact with the aligning portion, and the aligning portion is inclined in a direction opposite to a feeding direction of the print medium with respect to a reference line that passes through a center of the forward roller and passes through a center of the separating nip.

15. The image forming apparatus of claim 13, wherein the separating member comprises a separating roller engaged with the forward roller to form the separating nip, and the image forming apparatus further comprises a torque limiter to selectively allow driven rotation of the separating roller by the forward roller based on a magnitude of torque applied to the separating roller.