JP3932194B2 - Sheet feeding device - Google Patents

Description

  The present invention relates to a sheet feeding device that is used in an image forming apparatus such as a copying machine, a printer, or a facsimile machine and conveys a sheet such as a document or a recording sheet.

  In general, an image forming apparatus is provided with a sheet feeding device for transporting a sheet such as a document or a recording sheet. For example, in an automatic document feeding device that transports a document as a sheet, a large number of documents ( Document bundles) are separated one by one and fed (conveyed) to an image reading position such as a scanner device. Such an automatic document feeder is provided with a document feeding tray (sheet stacking tray) on which documents are stacked (set), and the document set on the document feeding tray is image-reading position by a document conveying mechanism. After the original is read here, it is discharged to the original discharge tray.

  Furthermore, even in a paper feeding device that feeds recording paper as a sheet to an image forming unit that forms a toner image via a paper conveyance path, the recording paper is fed from a paper tray (sheet stacking tray) on which recording paper is loaded. The sheets are separated one by one and fed to the image forming unit via a sheet conveyance path.

  In the sheet feeding apparatus, it is necessary to separate and transport the sheets one by one, regardless of the amount of sheets on the sheet stacking tray. For this reason, the sheet feeding device feeds the side of the bottom plate on which a large number of sheets are stacked. Guide pins are planted outward in a direction orthogonal to the direction, a guide groove in the vertical direction is provided in the bottom plate guide of the paper feed cassette corresponding to the guide pin, and the guide pin is inserted into the guide groove.

  A compression spring is engaged between the bottom plate and the paper feed cassette to urge the bottom plate upward, and the bottom plate is raised while maintaining a horizontal state. As a result, the angle of contact with the inclined surface of the inclined member of the sheet fed by the sheet feeding roller loaded on the bottom plate is always kept constant regardless of the amount of the sheet, and the separation performance is stabilized. (See Patent Document 1).

  Further, in the paper feeding device, the transfer paper stacking section is arranged from the upstream side in the feeding direction of the transfer paper in order to improve the separation performance while keeping the height of the uppermost paper of the loaded transfer paper to be substantially constant. A fixed portion that is inclined so as to descend toward the downstream side, a feeding position that is inclined more horizontally than the inclination of the fixed portion according to the rotation, and a separation position that is inclined more vertically than the inclination of the fixed portion. A movable portion that swings between them, and the movable portion is rotated between a paper feeding position and a separation position by an elevating mechanism, and in the paper feeding operation, the leading end portion of the transfer paper is bent by raising and lowering, There is one in which the adhesion between transfer sheets is weakened (see Patent Document 2).

  Further, in the automatic document feeder, the document feeding table of the document setting unit is divided into a first document feeding table having a driving unit and a second document feeding table having no driving unit. There is an arrangement in which the first and second document feed tables can be rotated independently, and only a necessary range of the upper space of the stack portion is opened to take out the discharged document. Then, the document feed table itself (first and second document feed tables) is raised, the document bundle set in the document feed table is brought into contact with the calling roller, and the uppermost document in the document bundle Are separated and fed (see Patent Document 3).

JP 2002-274663 A (paragraphs (0017) to (0022), FIGS. 1 to 4) JP 2001-328730 A (paragraph (0032) to paragraph (0051), FIGS. 1 to 3) JP 2001-139162 (paragraph (0020) to paragraph (0058), FIGS. 1 to 4)

  However, in the conventional sheet feeding device described in Patent Document 1, the angle of contact with the inclined surface of the inclined member of the sheet fed by the sheet feeding roller is always kept constant regardless of the amount of the sheet. It is necessary to raise itself while maintaining a horizontal state, and when the whole bottom plate is raised, when a large amount of sheets are stacked, the bottom plate receives the full load of the sheet, resulting in a driving mechanism such as a biasing means. There is a problem that becomes a large scale.

  Further, in the conventional sheet feeding device described in Patent Document 2, the movable portion is rotated between the paper feeding position and the separation position by the lifting mechanism, and the leading end portion of the transfer paper is moved up and down during the paper feeding operation. Although it is bent to weaken the adhesion between each transfer paper, since the movable part is rotated, in a state where a large amount of sheets are stacked, a large load is applied to the movable part, In addition, there is a problem that it is difficult to accurately position the sheet at the sheet feeding position.

  Further, in the conventional sheet feeding device described in Patent Document 3, the document feeding table of the document setting unit is divided into first and second document feeding tables, and the first and second document feeding tables are respectively provided. In this sheet feeding apparatus, the document feeding table itself (first and second document feeding tables) is raised and the bundle of documents set in the document feeding table, although it can be rotated independently. The mechanism for raising and lowering the document table is enlarged due to the fact that the topmost document of the document bundle is separated and fed by bringing it into contact with the roller, and that a large number of sheets are stacked. Considering this, there is a problem that the driving mechanism must be made larger.

  An object of the present invention is to supply a sheet stably even if a large amount of sheets are stacked on the sheet stacking unit regardless of the number of sheets stacked on the sheet stacking unit with a simple configuration and at low cost. It is an object of the present invention to provide a sheet feeding apparatus that can handle the above.

According to the present invention, the sheet stacking unit on which the sheet bundle is mounted, the sheet feeding mechanism that feeds sheets one by one from the sheet stacking unit in a predetermined transport direction, and the sheet stacking unit are supported. In the sheet feeding apparatus including the apparatus housing, the sheet stacking unit is separated into a first stacking unit located on the downstream side in the transport direction and a second stacking unit positioned on the upstream side in the transport direction. The first stacking unit is supported by the apparatus housing so as to be movable in the vertical direction, and the first stacking unit is moved in the vertical direction according to the number of the sheet bundles and is positioned at the uppermost position. A first gist includes a driving mechanism that positions a sheet at a predetermined position with respect to the sheet feeding mechanism .

Furthermore, in the present invention, a bridging portion that communicates the first and second stacking portions is provided, and the bridging portion is at the downstream end in the transport direction at the upstream end in the transport direction of the first stacking portion. The second stacking unit is supported so as to be rotatable about an axis extending in the width direction of the first stacking unit, and the upstream end in the transport direction of the bridge unit is in contact with the upper surface of the second stacking unit. Is provided with an inclined surface that is inclined obliquely downward toward the downstream side in the conveying direction, and the second aspect is to bring the upstream end of the bridge portion in the conveying direction into contact with the inclined surface .

  In the present invention, the position of the sheet stacking surface of the first stacking unit is defined as a reference plane when the first stacking unit is located at a predetermined reference position, and the first stacking unit is When the first stacking unit is moved upward from the reference plane and the first stacking unit moves in the vertical direction, the first stacking unit is guided in parallel with the reference plane.

  For example, the guide means includes a rack that is provided in the apparatus housing and extends in the vertical direction, and a pinion that meshes with the rack and moves along the rack, and the pinion rotates to the first stacking unit. It is installed as possible.

  Further, according to the present invention, the drive mechanism extends in the width direction of the first stacking portion intersecting the transport direction, and is rotatably supported by the apparatus housing, and rotates the drive shaft body. Driving means for driving, and a driving member having one end attached to the driving shaft body and rotating about the driving shaft body as a fulcrum, and the other end portion of the driving member on the lower surface of the first stacking portion The drive means has a drive motor and a connection mechanism for connecting the drive motor and the drive shaft body, and the drive motor and the connection mechanism are arranged on the outer surface side of the apparatus housing. It is desirable to do.

  In the sheet feeding device according to the present invention, the sheet stacking unit is separated into a first stacking unit located on the downstream side in the transport direction and a second stacking unit located on the upstream side in the transport direction. The stacking unit is supported by the apparatus housing so as to be movable in the vertical direction, and the first stacking unit is moved in the vertical direction according to the number of sheet bundles so that the uppermost sheet is moved with respect to the sheet feeding mechanism. Since the uppermost sheet is positioned at a predetermined position with respect to the sheet feeding mechanism, it is not necessary to drive the sheet stacking unit on which a load of the entire sheet bundle is applied. There is an effect that the sheet bundle can be moved up and down by the driving source. As a result, the sheet can be stably fed with a simple configuration and at a low cost regardless of the number of sheets stacked on the sheet stacking unit.

  In the sheet feeding device of the present invention, the bridging portion that connects the first and second stacking units is connected to the downstream end of the first stacking unit at the downstream end of the first stacking unit. Since the upstream end of the bridging portion in the conveyance direction is in contact with the upper surface of the second stacking portion, the first stacking portion is moved when the sheet is conveyed. Even if it moves in the vertical direction, the bridging portion rotates around the fulcrum axis in accordance with the movement of the first stacking unit, so that the sheet conveyance from the sheet stacking unit is not hindered.

  In the present invention, when the first stacking unit moves in the vertical direction, the first stacking unit is guided in parallel to the reference plane, so that the document feeding position is always fixed regardless of the number of documents. The position can be set, and there is an effect that stable paper feeding can always be performed.

  In the present invention, the drive mechanism extends in the width direction of the first stacking portion intersecting the sheet conveying direction and is rotatably supported by the apparatus housing, and one end of the drive mechanism is attached to the drive shaft body. And a drive member that rotates about the drive shaft, with the other end of the drive member abutting against the lower surface of the first stacking portion, Since the first loading unit is raised and lowered as described above, the first loading unit can be raised and lowered with a simple configuration, and as described above, the load applied to the first loading unit is Since there are few compared with the whole sheet | seat stacking part, a drive source can be made small. At this time, if the drive motor and the connection mechanism for connecting the drive motor to the drive shaft body are arranged on the outer surface side of the apparatus housing, the drive motor and the connection mechanism do not exist in the sheet stacking portion. Not only can the first stacker be driven smoothly, but the weight of the sheet stacker itself can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

  First, referring to FIG. 1, an automatic document feeder will be described as an example of a sheet feeder, but the present invention can be similarly applied to a recording paper transport device. FIG. 1 is a perspective view showing an appearance of an automatic document feeder 10. The illustrated automatic document feeder 10 is used together with an image forming apparatus (for example, a copying machine), and an image forming apparatus (not shown) main body. It is arrange | positioned at the upper surface side. The automatic document feeder 10 includes a document feeding tray (sheet stacking unit) 11 and a document feeding mechanism (sheet feeding mechanism) 12. The document feeding tray 11 and the document feeding mechanism 12 are configured to automatically feed documents. It is attached to a feeding device housing (hereinafter simply referred to as a device housing) 21. In FIG. 1, the document feeding mechanism 12 is covered with a cover body 21a. The cover body 21a is rotatable about one end portion (left end portion in FIG. 1) as a fulcrum shaft. When the other end is gripped and the cover body 21a is opened and closed, the document feeding mechanism 12 is exposed.

  The bottom surface of the apparatus housing 21 defines a document discharge tray 15, and the document discharge tray 15 is positioned below the document feed tray 11. Then, as will be described later, the documents set on the document feed tray 11 are sent one by one to the document reading position by the document feeding mechanism 12 and then discharged to the document discharge tray 15.

  Referring also to FIG. 2, as described above, when a document bundle is stacked (set) on the document feed tray 11 and the copy button is pressed, the document feed mechanism 12 moves the document feed tray 11 onto the document feed tray 11. The originals are separated one by one from the stacked original bundle, and the originals are conveyed to the first image reading position GP1.

  Then, after an image on one side of the original is read by the first scanner unit (not shown) at the first image reading position GP1, the original is sent to the second original reading position GP2, and then the second image reading position GP1. The document on the other side of the document is read by the scanner unit 13. Then, the original is discharged to the original discharge tray 15 by the discharge roller pair 16.

  The illustrated automatic document feeder 10 is compatible with double-sided printing. When single-sided printing is performed, for example, the image on the original is read only at the first image reading position GP1. Although not shown, in the image forming apparatus, an image carrier such as a photosensitive drum is exposed based on image data obtained by reading a document, and an electrostatic latent image is formed on the image carrier. . Then, after developing the electrostatic latent image by the developing device, the toner image on the image carrier is transferred to a recording sheet, the toner image on the recording sheet is fixed, and the sheet is discharged onto a sheet discharge tray.

  As shown in FIG. 2, the document feeding mechanism 12 is disposed on the rear side of the document feeding tray 11 (downstream in the document transport direction). The document feeding mechanism 12 includes a document feeding roller section (hereinafter simply referred to as “sheet feeding roller unit”). The document feed roller unit 14 includes a roller housing 14a, a pickup roller (pickup roller) 14b, a feed mechanism 14c, and a separation roller 14d.

  The feed mechanism 14 c includes a pair of feed rollers (feed rollers) 141, a feed belt 142 is stretched around the feed rollers 141, and a separation roller 14 d is in contact with the feed belt 142. The pickup roller 14b and the feed mechanism 14c are housed in a roller housing 14a, and the separation roller 14d is provided on the base side of the document feeding mechanism 12. Instead of the above-described feed mechanism 14c, a single feed roller 141 may be provided, and the feed roller 141 may be disposed to face the separation roller 14d.

  As shown in FIGS. 1 and 2, the document feed tray 11 includes a first tray unit (first stacking unit) 11a located on the document feeding mechanism 12 side (that is, downstream in the document transport direction), And a second tray portion (second stacking portion) 11b located upstream in the document transport direction, and the second tray portion 11b has the downstream end in the document transport direction as a fulcrum shaft. When the document bundle ejected to the document delivery tray 15 is taken out, the second tray portion 11b is pivoted upward about the fulcrum shaft to eject the delivery document bundle. Is taken out from the document discharge tray 15.

  The first tray section 11a is mounted on the apparatus casing 21 so as to be movable in the vertical direction in the figure (the direction indicated by the solid line arrow in the figure) with respect to the apparatus casing 21. A bridging portion 11c is attached to the upstream end in the direction so as to be rotatable about a fulcrum shaft 22 extending in the width direction of the apparatus housing 21, and a portion of the bridging portion 11c on the upstream side in the document conveying direction is It is in contact with the upper surface of the second tray portion 11b.

  As shown in FIG. 2, the second tray portion 11b has an inclined surface 11d whose upper surface is inclined obliquely downward at a portion downstream of the document conveying direction, and the bridging portion 11c is formed on the inclined surface 11d. The portion on the upstream side in the document transport direction is in contact. A document guide 23 for defining the document width is provided on the upper surface of the first tray unit 11a. The first tray unit 11a is fixedly attached to the document feeding mechanism 12, and the first tray unit 11a The downstream end in the document transport direction is located downstream of the pickup roller 14b.

  The first tray portion 11a is driven upward from the reference position (initial position) shown in FIG. When the first tray unit 11a is positioned at the reference position, the position of the upper surface (document stacking surface) of the first tray unit 11a is used as the reference surface. When the first tray portion 11a is at the reference position, as shown in FIG. 2, the lower surface of the bridging portion 11c is in contact with the inclined surface 11d, and the first tray portion 11a is in the second position. It is located below the tray part 11b.

  Now, when a bundle of documents is placed on the document feed tray 11, a document is detected by a document detection sensor (not shown), whereby the first tray portion 11a is driven by the tray drive mechanism 24, and the document is detected at the maximum. The first tray portion 11a is raised until the document at the upper position contacts the pickup roller 14b. Then, the original is picked up by the pickup roller 14b, and only one of the originals picked up by the pickup roller 14b is separated by the separation roller 14d and sent out downstream by the feed mechanism 14c.

  As shown in FIG. 2, the document feeding mechanism 12 has a document feeding section 20 disposed on the downstream side of the feed mechanism 14c. The document feeding section 20 includes a large-diameter driving roller 25 and a small-diameter driving roller 25. The driven rollers 26 and 27 are provided, and the peripheral surfaces of the driven rollers 26 and 27 are in contact with the peripheral surface of the drive roller 25. Then, the document is sent to the first document reading position GP1 by the document feeding section 20, and then passes through the second document reading position GP2 and is discharged to the document discharge tray 15.

  As the document is fed, the number of documents on the document feed tray 11 decreases. As described above, the uppermost document on the document feed tray is detected by the document detection sensor. Accordingly, the tray driving mechanism 24 is driven and controlled so that the uppermost document is always positioned at the same position with respect to the pickup roller 14b (that is, the uppermost document is positioned at a predetermined position). At this time, the bridging portion 11c rotates around the fulcrum shaft 22 in the direction indicated by the dashed arrow (clockwise) as the first tray portion 11a rises, as if the bridging portion 11c is upstream in the document conveyance direction. It will turn as if it is a fulcrum.

  FIG. 3 shows a state in which the first tray portion 11a is raised most (state where the first tray portion 11a is raised to the maximum raised position). In this state, the upper surface of the first tray portion 11a is in contact with the pickup roller 14b. Then, when it rises to the maximum ascending position, the first tray portion 11a is moved downward by the tray driving mechanism 24 and returned to the reference position (initial position). Even before the first tray portion 11a reaches the maximum ascending position, the first tray portion 11a descends when there are no more documents on the document feed tray 11.

  4 and 5, FIG. 4 is a perspective view of the first tray portion 11a as viewed from above, and FIG. 5 is a perspective view of the first tray portion 11a as viewed from below. The aforementioned tray drive mechanism 24 has a guide portion 241, and as shown in the figure, this guide portion 241 is attached to the lower outer surface of the first tray portion 11 a, and the guide portion 241 is attached to the apparatus housing 21. A support member 31 extending in the width direction is provided, and plate-like flange portions 31a and 31b projecting downward are formed at both ends in the width direction of the support member 31, respectively.

  A rotary shaft 32 is rotatably disposed between the flange portions 31a and 31b, and a pair of pinions 24d are rotatably disposed at a predetermined interval on the flange portion 31a. Are engaged with each other. Similarly, a pair of pinions 24e are rotatably disposed at a predetermined interval on the flange portion 31b, and these pinions 24e are engaged with each other (only one of the pinions 24e is visible in FIG. 5). The pinions 24 d and 24 e are opposed to each other, and one of the pinion 24 d and the pinion 24 e that are opposed to each other is connected by the rotary shaft body 32. The pinion 24d meshes with a rack 24c, which will be described later, and the pinion 24e meshes with a rack 24f (not visible in FIG. 5), and a guide portion 241 is constituted by these rack and pinions.

  Furthermore, the tray drive mechanism 24 has a rotation drive shaft body 24a extending in the width direction of the apparatus housing 21, and a drive stay portion (drive member) 24b having one end attached to the rotation shaft body 24a. The portion 24b extends in the document transport direction along the lower surface of the first tray portion 11a (the lower surface of the support member 31). As will be described later, the rotary drive shaft 24a is connected to a drive motor 34 (see FIG. 6, omitted in FIGS. 4 and 5) via a gear train (transmission mechanism) 33 (omitted in FIG. 4). When the drive motor 34 is rotationally driven, the rotational drive shaft body 24a rotates via the gear train 33, and the drive stay portion 24b rotates about the rotational drive shaft body 24a.

  Here, referring to FIGS. 6 and 7, FIG. 6 shows a state in which the cover member (the portion indicated by reference numeral 21b in FIG. 1) and the first tray portion 11a provided on the side portion of the apparatus housing 21 are removed. FIG. 7 is a perspective view shown from one side, while FIG. 7 is a perspective view shown from the opposite side. As shown in FIG. 6, the above-described pair of racks 24f are attached to the inner surface of the side plate portion 21c of the apparatus housing 21, and these racks 24f extend upward. As shown in FIG. 7, the pair of racks 24c described above are attached to the inner surface of the side plate portion 21d of the apparatus housing 21, and these racks 24c extend upward.

  As shown in FIGS. 6 and 7, a gear train support member 35 is attached to the outer surface side of the side plate portion 21c, and a gear train 33 is rotatably housed and supported in the gear train support member 35. A drive motor 34 is attached to the outer surface of the column support member 35, and the drive motor 34 is connected to the rotary drive shaft body 24 a via the gear row 33. The rotation drive shaft 24a is rotatably supported between the side plate portions 21c and 21d. Thus, if the drive motor 34 and the gear train 33 are arranged on the side of the side plate portion 21c, the drive motor 34 and the continuous gear train 33 do not exist in the document feed tray 11, so the first tray portion 11a can be driven smoothly, and the document feed tray itself can be reduced in weight.

  With reference to FIGS. 2 and 3 and FIGS. 8 and 9, when the drive motor 34 is rotationally driven in the forward direction, the rotational drive shaft 24a rotates in the forward direction. As a result, as shown in FIGS. 8 and 9, the drive stay 24b having one end attached to the rotary shaft 24a rotates upward with the rotary drive shaft 24a as a fulcrum, and the other end of the drive stay 24b. The portion rises and presses the lower surface of the first tray portion 11a (the lower surface of the support member 31) upward.

  The first tray portion 11a is lifted upward from the reference position shown in FIG. 5 by the upward rotation of the drive stay portion 24b. In this case, the first tray portion 11a is moved to the guide portion 241. Guided will rise. That is, the pinion 24d moves upward while meshing with the rack 24c. Similarly, the pinion 24e moves upward while meshing with the rack 24f, and the first tray portion 11a remains parallel to the reference plane. , The pinions 24d and 24e and the racks 24c and 24f are guided to rise. In other words, the first tray portion 11a is guided by the guide portion 241 (along the racks 24c and 24f) and moves upward while maintaining a state parallel to the reference plane.

  Then, as described above, the first tray portion 11a is raised until the document at the uppermost position contacts the pickup roller 14b, the document is picked up by the pickup roller 14b, and the pickup roller 14b is picked up by the separation roller 14d. Only one of the picked-up documents is separated and sent to the downstream side by the feed mechanism 14c.

  On the other hand, when the drive motor 34 is rotationally driven in the reverse direction, the rotational drive shaft body 24a rotates in the reverse direction, and the drive stay portion 24b rotates downward with the rotational drive shaft body 24a as a fulcrum, thereby the first tray. The portion 11a moves while maintaining a parallel state below the drive stay portion 24b. Also at this time, the first tray portion 11a moves downward while being guided by the guide portion 241 (that is, the racks 24c and 24f and the pinions 24d and 24e). If the drive motor 34 is turned off after all the originals have been sent, the first tray portion 11a falls while being guided by the guide portion 241 by its own weight, and returns to the reference position.

  FIG. 10 is a diagram schematically showing a state in which the first tray portion 11a is lifted upward from the reference position. The first tray portion 11a is guided to the guide portion 241 from the reference position shown in FIG. As shown in FIG. 10C, the upper surface of the first tray portion 11a comes into contact with the pickup roller 14b as shown in FIG. 10C. The first tray portion 11a is raised in a state where it is not). At this time, as shown in FIG. 10 (a), at the reference position, the lower surface of the bridging portion 11c is in contact with the inclined surface 11d of the second tray portion 11b. When the tray portion 11a rises, the bridging portion 11c rotates clockwise around the fulcrum shaft 22, and as shown in FIG. 10 (b), the lower surface of the bridging portion 11c is gradually separated from the inclined surface 11d, The bridging portion 11c comes into contact with the inclined surface 11d at the upstream end in the document transport direction, and finally enters the state shown in FIG.

  In this way, the first tray portion 11a is raised while maintaining the parallel state by the guide portion 241. At this time, the bridging portion 11c rotates around the downstream end in the document conveying direction as a fulcrum. Since the communication between the section 11a and the second tray section 11b is maintained, the document can be accurately positioned at the feeding position when the document is fed regardless of the number of documents.

  On the other hand, as shown in FIG. 11, if the guide portion 241 and the bridging portion 11c are not provided, when the first tray portion 11a is lifted by the drive stay portion 24b from the position shown in FIG. With the upward rotation of 24b, as shown in FIG. 11B, the leading end side (document feeding mechanism side) of the first tray portion 11a is lifted from the trailing end side, and the document feeding tray 11 The uppermost position of the original (the position of the leading edge of the original) differs depending on the number of upper originals. In other words, when the number of documents on the document feed tray 11 decreases as a result of document reading, the first tray portion 11a moves upward by the rotation of the drive stay portion 24b. The top end of the tray portion 11a is lifted, the uppermost position of the original is changed as the first tray 11a is raised, and when the number of originals changes, the original can be accurately positioned at the feeding position. It will disappear.

  As described above, in the first exemplary embodiment, the document feed tray 11 is positioned on the document feed mechanism 12 side (downstream side in the document transport direction) and on the upstream side in the document transport direction. Separately from the second tray portion 11b, only the first tray portion 11a is moved in the vertical direction according to the number of documents, and the uppermost document end is brought into contact with the pickup roller 14b. Considering that the load of the entire document bundle is applied to the entire first and second tray portions 11a and 11b, the load applied to the first tray portion 11a is reduced, and the first tray portion 11a is reduced accordingly. The drive source for driving can be reduced in size.

  Further, a bridging portion that is rotatable around a fulcrum shaft provided at the upstream end in the document transport direction of the first tray portion 11a is disposed between the first tray portion 11a and the second tray portion 11b. Therefore, even if the first tray portion 11a is driven in the vertical direction, the communication with the first and second tray portions 11a and 11b is maintained well, and document feeding is not hindered. .

  Further, when the first tray portion 11a is raised, the first tray portion 11a is raised while maintaining a parallel relationship with the reference plane by the guide portion 241. Therefore, the first tray portion 11a is always raised regardless of the number of documents. The document can be accurately positioned at the document feeding position.

  As shown in FIG. 10, since the document discharge tray 15 is gradually lifted toward the downstream side in the discharge direction, the document discharged to the document discharge tray 15 is the rear end of the document discharge tray 15. The paper discharge speed is reduced on the side, so that the discharged original document does not fall from the document discharge tray 15.

  The sheet stacking unit is separated into a first stacking unit located on the downstream side in the sheet conveying direction and a second stacking unit located on the upstream side in the sheet conveying direction, and the first stacking unit is moved up and down. The first sheet stacking unit is moved up and down according to the number of sheet bundles, and the uppermost sheet is positioned at a predetermined position with respect to the sheet feeding mechanism. To do. At this time, the first stacking unit is moved upward from a predetermined reference position, and when the first stacking unit moves in the vertical direction, the first stacking unit is guided in parallel to the reference position. Therefore, the present invention can be applied not only to feeding a document on a document feeding tray but also to a sheet feeding device that feeds recording paper.

1 is a perspective view illustrating an appearance of an automatic document feeder that is an example of a sheet feeder according to the present invention. FIG. FIG. 2 is a cross-sectional view illustrating the automatic document feeder illustrated in FIG. 1 with a first tray portion in an initial position. FIG. 2 is a cross-sectional view illustrating the automatic document feeder illustrated in FIG. 1 in a state where a first tray portion is at a maximum raised position. It is a perspective view which shows the 1st tray part shown in FIG. 2 from upper direction. It is a perspective view which shows the 1st tray part 11a shown in FIG. 2 from the downward direction. It is a perspective view which shows the state which removed the cover member with which the side part of the apparatus housing | casing was equipped, and the 1st tray part from one side. It is a perspective view which shows the state which removed the cover member with which the side part of the apparatus housing | casing was equipped, and the 1st tray part from the side of the other side. It is a perspective view which shows the state which the 1st tray part shown in FIG. 2 raised along the guide part from the downward direction. FIG. 3 is a diagram illustrating a state in which a first tray portion illustrated in FIG. 2 is raised along a guide portion from a document conveyance direction. FIG. 4 is a cross-sectional view schematically showing the movement (upward movement) of the first tray portion in the automatic document feeder according to the present invention, and (a) is a view showing a state where the first tray portion is in an initial position; (A) is a figure which shows the state which the 1st tray part raised to the middle, (c) is a figure which shows the state which has the 1st tray part in the maximum raise position. It is sectional drawing which shows schematically a movement of the 1st tray part when a guide part and a bridge part do not exist, (a) is a figure which shows the state which has a 1st tray part in an initial position, (b) FIG. 4 is a view showing a state where the first tray portion is at a maximum ascending position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Document automatic feeder 11 Document feed tray 11a 1st tray part 11b 2nd tray part 11c Bridging part 11d Inclined surface 12 Document feed mechanism 13 2nd scanner unit 14 Document feed roller part 15 Document discharge Paper tray 16 Discharge roller pair 21 Device housing 22 Support shaft 24 Tray drive mechanism 24a Rotation drive shaft 24b Drive stay 24c, 24f Rack 24d, 24e Pinion 241 Guide 31 Support members 31a, 31b Flange 32 Rotation shaft 33 Gear train 34 Drive motor 35 Gear train support member

Claims (5)

A sheet loading unit on which a sheet bundle is loaded; a sheet feeding mechanism that feeds sheets one by one from the sheet stacking unit in a predetermined conveyance direction; and an apparatus housing that supports the sheet stacking unit. In the sheet feeding device,
The sheet stacking unit is separated into a first stacking unit located on the downstream side in the transport direction and a second stacking unit located on the upstream side in the transport direction,
The first stacking unit is supported by the apparatus housing so as to be movable in the vertical direction,
A drive mechanism for moving the first stacking unit in the vertical direction according to the number of the sheet bundles to position the uppermost sheet at a predetermined position with respect to the sheet feeding mechanism ;
A bridging portion connecting the first and second loading portions;
The bridging portion is supported at the downstream end in the transport direction so as to be rotatable around an axis extending in the width direction of the first stacking portion at the upstream end in the transport direction of the first stacking portion.
Conveyance direction upstream end of the bridging portion is brought into contact with the upper surface of the second stacking portion,
Furthermore, the second stacking unit has an inclined surface inclined obliquely downward toward the downstream side in the transport direction,
The sheet feeding apparatus according to claim 1, wherein an upstream end of the bridge portion in the conveyance direction is in contact with the inclined surface. When the first stacking unit is positioned at a predetermined reference position, the position of the sheet stacking surface of the first stacking unit is defined as a reference plane, and the first stacking unit moves upward from the reference plane. And
Wherein when the first stacking portion is moved in the vertical direction, the sheet feeding apparatus according to claim 1, characterized in that it comprises a guide means for guided parallel to the first stacking portion to the reference plane. The guide means includes a rack that is provided in the apparatus casing and extends in the vertical direction, and a pinion that meshes with the rack and moves along the rack.
3. The sheet feeding apparatus according to claim 2, wherein the pinion is rotatably mounted on the first stacking unit. The drive mechanism extends in the width direction of the first stacking unit intersecting the transport direction, and is rotatably supported by the apparatus housing, and drive means for rotationally driving the drive shaft body, A drive member having one end attached to the drive shaft body and rotating about the drive shaft body as a fulcrum;
Sheet feeding apparatus according to claim 1 to 3 or 1, wherein said the other end portion of the drive member is in contact with the lower surface of the first stacking section. The drive means includes a drive motor, and a connection mechanism that connects the drive motor and the drive shaft body,
The sheet feeding apparatus according to claim 4, wherein the drive motor and the coupling mechanism are disposed on an outer surface side of the apparatus housing.

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