Document feeder and image forming device provided therewith

Abstract

To provide a document feeder that is less likely to cause transport errors and can transport documents stably.SOLUTION: The document feeder 160 has a document transport path L that transports a document G to a first document reading position A1 and a second document reading position A2 for image reading. Furthermore, the document transport path L includes a curved transport path La, and is provided with a document feeding roller 21 that feeds the document G to the curved transport path La, and a large-diameter transport roller 24 that is located inside the curved transport path La and has a larger diameter than the document feeding roller 21. The document transport speed by the large-diameter transport roller 24 is greater than the document transport speed by the document feeding roller 21.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a document feeder that conveys a document along a curved conveyance path and an image forming apparatus including the same.

Background Art

[0002] Generally, image forming apparatuses such as copiers, facsimile machines, printers, and multifunction peripherals include a document feeder that conveys a document and reads the front or back surface of the document. The document feeder conveys one or more documents placed on a document placement tray one by one, and reads the document in a reading unit while it is being conveyed. By reading the document, image data such as an image formed on the read document is generated.

[0003] In this way, in the image forming apparatus, copying, fax transmission, scanning, etc. are performed in order for one or more documents. However, in the document feeder, when conveying a document, there is a problem that the conveyance becomes unstable, and the document is conveyed in an inclined state or a conveyance jam occurs. In particular, in a document feeder having a curved conveyance path, there is a problem that such a problem easily occurs.

[0004] Therefore, various techniques for preventing such problems have been proposed. For example, in the paper conveyance device disclosed in Patent Document 1, a guide member is provided in the paper conveyance path, and when both ends of the guide member are screwed to the frame of the device, due to the stress during screwing, the middle portion of the guide member is forcibly deformed in the direction opposite to the paper path surface, and the paper is guided to a curved paper conveyance path disposed between the supply tray and the discharge tray. According to the paper conveyance device disclosed in Patent Document 1, when both ends of the guide member are screwed to the frame of the device, due to the stress during screwing, the middle portion of the guide member is forcibly deformed in the direction opposite to the paper path surface, so that it is possible to prevent the upstream end portion of the guide from protruding and to prevent the occurrence of paper jams in the paper conveyance path.

Prior Art Documents

[0005] [Patent Document 1] JP 2001-122471 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, various document feeders (paper transport devices) have been proposed in image forming apparatuses to prevent problems such as the document being transported at an angle or a transport jam occurring when transporting the document (paper); however, there is a demand for a document feeder that can transport documents (paper) more stably.

[0007] The present disclosure has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a document feeding device that is less likely to cause transport abnormalities and can transport documents stably, and an image forming apparatus equipped with the same. [Means for solving the problem]

[0008] A document feeding device according to one aspect of the present disclosure is a document feeding device having a document transport path that transports a document to a document reading position for reading an image, the document transport path including a curved transport path, and is characterized in that it is equipped with a paper feed roller that feeds the document to the curved transport path, and a large diameter transport roller arranged inside the curved transport path and having a diameter larger than that of the paper feed roller, and the document transport speed by the large diameter transport roller is greater than the document transport speed by the paper feed roller.

[0009] This allows a sufficient distance between the sheets when the original is transported, and also allows for stable original transport. This prevents problems such as the original being transported at an angle or a transport jam, and makes it difficult for transport abnormalities to occur, allowing the original to be transported stably.

[0010] In addition, in the above-described document feeder, it may be provided with a single driven roller that is in pressure contact with the large-diameter conveyance roller and rotates passively, the document reading position is arranged on the downstream side of the large-diameter conveyance roller, and the driven roller is disposed between the paper feed roller arranged on the upstream side of the large-diameter conveyance roller in the document conveyance path and the document reading position, and is arranged closer to the document reading position than the paper feed roller.

[0011] In this way, since the driven roller is arranged closer to the document reading position between the paper feed roller and the document reading position in the document conveyance path, abnormal conveyance of the document is less likely to occur, and the document can be stably conveyed.

[0012] In addition, in the above-described document feeder, it may be provided with a paper discharge roller that is arranged on the downstream side of the large-diameter conveyance roller and discharges the document read at the document reading position to the outside, and the paper feed roller, the large-diameter conveyance roller, and the paper discharge roller may be rotationally driven by the same motor.

[0013] Thereby, the document can be stably conveyed with a simple configuration without increasing the number of parts. Therefore, the manufacturing cost can be suppressed.

[0014] In addition, in the above-described document feeder, each of the paper feed roller, the large-diameter conveyance roller, and the paper discharge roller may be connected to the motor by a transmission mechanism including gears.

[0015] Thereby, the document can be stably conveyed with a simple configuration without increasing the number of parts. Therefore, the manufacturing cost can be suppressed.

[0016] In addition, in the above-described document feeder, in the document conveyance path, it may be such that no conveyance roller other than the large-diameter conveyance roller is arranged between the paper feed roller and the driven roller.

[0017] Thus, with a simple configuration, the document can be stably conveyed without increasing the number of components. Therefore, the manufacturing cost can be reduced.

[0018] Further, in the above-described document feeder, the driven roller may be disposed below a horizontal plane including the rotation axis of the large-diameter conveyance roller.

[0019] In this way, since the driven roller is disposed below the horizontal plane including the rotation axis of the large-diameter conveyance roller, conveyance abnormalities of the document are less likely to occur, and the document can be stably conveyed.

[0020] Further, in the above-described document feeder, a paper discharge roller is provided downstream of the large-diameter conveyance roller for discharging the document read at the document reading position to the outside. The document reading position includes a first document reading position for reading one side of the document and a second document reading position for reading the other side of the document, and the second document reading position is located downstream of the first document reading position in the document conveyance path and may be closer to the paper discharge roller than the first document reading position.

[0021] Thereby, the document can be stably conveyed, and further, the reading of the document can be smoothly performed.

[0022] Further, in the above-described document feeder, during the document feeding operation, the motor may not stop except when an error occurs.

[0023] Thereby, the control of the motor becomes easy, and the burden on the overall control can be reduced.

[0024] Further, in the above-described document feeder, a paper discharge roller is provided downstream of the large-diameter conveyance roller for discharging the document read at the document reading position to the outside, and no roller for conveying the document may be provided between the driven roller and the paper discharge roller.

[0025] As a result, the configuration can be further simplified, the number of components can be reduced, and the manufacturing cost can be suppressed.

[0026] The image forming apparatus according to one aspect of the present disclosure is characterized by including the above-described document feeder.

[0027] As a result, in the document feeder, it is possible to ensure a sufficient distance between sheets during document conveyance and perform stable document conveyance. Therefore, it is possible to suppress problems such as the document being conveyed in an inclined state or a conveyance jam occurring, make it difficult for conveyance abnormalities to occur, and stably convey the document. Thereby, stable image formation can be performed.

Advantages of the Invention

[0028] According to the present disclosure, it is possible to provide a document feeder that can stably convey a document without causing a conveyance abnormality, and an image forming apparatus including the same.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0030] Embodiments according to the present disclosure will be described with reference to the drawings.

[0031] (First Embodiment) An image forming apparatus according to a first embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a front view perspectively showing the schematic configuration of the image forming apparatus according to the first embodiment of the present disclosure.

[0032] Here, in the coordinates shown in the figures below, the X-axis direction indicates the left-right direction (horizontal direction) when viewing the image forming apparatus 100 from the front, and the positive X-axis direction and the negative X-axis direction represent the left side and the right side, respectively. The Y-axis direction indicates the depth direction (front-rear direction) perpendicular to the X-axis, which is the left-right direction, and the positive Y-axis direction and the negative Y-axis direction represent the operation side (front side) and the back side, which is the opposite side of the operation side, respectively. The Z-axis direction represents the up-down direction, that is, the vertical direction, and the positive Z-axis direction and the negative Z-axis direction represent the upper side and the lower side, respectively. When only the constituent members of the image forming apparatus 100 are shown without showing the image forming apparatus 100, the coordinates in the state where the constituent members are incorporated in the image forming apparatus 100 are shown.

[0033] The image forming apparatus 100 is a multifunction device having a copy function, a scanner function, a facsimile function, and a printer function, and includes an image reading device 102 and an image forming apparatus main body 101.

[0034] The image reading device 102 includes a reading unit 130 and a document feeder 160 [automatic document feeder (ADF)]. The document feeder 160 is provided above the reading unit 130 and is supported so as to be openable and closable with respect to the reading unit 130.

[0035] The document feeder 160 sequentially conveys one or more documents G one by one. The image reading device 102 reads the document G conveyed one by one by the document feeder 160 from among one or more documents G.

[0036] The reading unit 130 includes a document placement table 130a on which the document G is placed, and a scanning optical system 131 including a first document reading unit 132a. The scanning optical system 131 reads the document G.

[0037] The image reading device 102 has a function of reading a document G placed on the document placement table 130a. When the document feeder 160 is opened, the document placement table 130a above the reading unit 130 is exposed, and the document G can be manually placed on the document placement table 130a. The reading unit 130 scans the scanning optical system 131 to read the document placed on the document placement table 130a.

[0038] In addition, the document feeder 160 includes a document discharge tray 162 for stacking the documents G discharged to the outside, a document pickup roller 22 for pulling out the documents G stacked on the document discharge tray 162 one by one, a document feeding roller 21 for conveying the document G pulled out by the document pickup roller 22, a large-diameter conveying roller 24 for conveying the document G conveyed from the document feeding roller 21, a driven roller 25 arranged to be in pressure contact with the large-diameter conveying roller 24, a second document reading unit 132b for reading the back surface (the other surface) side of the conveyed document G, and a pair of document discharging rollers 26 for discharging the document G to the document discharge tray 162.

[0039] Although the details of the document feeder 160 will be described later, the document feeder 160 has a document conveyance path L (see FIG. 2) along which a document G is conveyed. A part of the document conveyance path L is a curved conveyance path La (see FIG. 2) that is curved in a U shape, and the curved conveyance path La is included in the document conveyance path L. Also, in the document conveyance path L, there are a first document reading position A1, which is a position for reading the front (one side) surface of the document G, and a second document reading position A2, which is a position for reading the back surface of the document G.

[0040] The image reading device 102 has a function of reading a conveyed document G that has been conveyed by the document feeder 160. The document feeder 160 conveys the document G placed on the document placement tray 161 to the first document reading position A1 where the first document reading unit 132a is disposed and the second document reading position A2 where the second document reading unit 132b is disposed. Thereby, when the document G is being conveyed along the document conveyance path L by the document feeder 160, the front surface side of the document G is read by the first document reading unit 132a at the first document reading position A1, and the back surface side of the document G is read by the second document reading unit 132b at the second document reading position A2. After the document G has been conveyed along the document conveyance path L, it is discharged to an external document discharge tray 162.

[0041] The image forming apparatus main body 101 includes an image transfer unit 50, an optical scanning device 1, an intermediate transfer belt device 70, a secondary transfer device 11, a fixing device 12, a sheet conveyance path S, a paper feed cassette 18, and a sheet discharge tray 141.

[0042] In the image forming apparatus 100, image data corresponding to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y), or a monochrome image using a single color (for example, black) is handled.

[0043] The image transfer unit 50 of the image forming apparatus 100 has four image stations Pa, Pb, Pc, and Pd corresponding to the colors black, cyan, magenta, and yellow. These image stations Pa, Pb, Pc, and Pd each include a developing device 2, a photosensitive drum 3, a drum cleaning device 4, and a charger 5, and four types of toner images are formed by these image stations Pa, Pb, Pc, and Pd. That is, in the image forming apparatus 100, four developing devices 2, four photosensitive drums 3, four drum cleaning devices 4, and four chargers 5 are provided, and each is associated with black, cyan, magenta, and yellow.

[0044] The optical scanning device 1 exposes the surface of the photosensitive drum 3 to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image on the surface of the photosensitive drum 3. The drum cleaning device 4 removes and recovers the residual toner on the surface of the photosensitive drum 3. The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential. By the above-described series of operations, toner images of each color are formed on the surface of each photosensitive drum 3.

[0045] The intermediate transfer belt device 70 includes an intermediate transfer roller 6, an endless intermediate transfer belt 71, an intermediate transfer driving roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. The intermediate transfer belt 71 is an endless belt that can move in a circumferential direction and is wound around the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73. That is, the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73 stretch the intermediate transfer belt 71. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71, respectively, so as to form four types of toner images corresponding to each color. The intermediate transfer roller 6 transfers the toner images of each color formed on the surface of the photosensitive drum 3 to the intermediate transfer belt 71.

[0046] The image forming apparatus 100 sequentially transfers and superimposes the toner images of respective colors formed on the surfaces of the photoreceptor drums 3, and forms a color toner image on the surface of the intermediate transfer belt 71 stretched between the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73. The toner image formed on the intermediate transfer belt 71 is transferred onto the sheet P by the secondary transfer device 11. Also, a part of the toner image formed on the intermediate transfer belt 71 remains on the surface of the intermediate transfer belt 71 as waste toner without being transferred onto the sheet P, and this waste toner is removed and collected by the cleaning device 9.

[0047] The secondary transfer device 11 forms a transfer nip region TN between the secondary transfer roller 11a and the intermediate transfer belt 71, and sandwiches and conveys the sheet P conveyed through the sheet conveyance path S into the transfer nip region TN. When the sheet P passes through the transfer nip region TN, the toner image on the surface of the intermediate transfer belt 71 is transferred and the sheet P is conveyed to the fixing device 12.

[0048] The fixing device 12 includes a fixing roller 31 and a pressure roller 32 that rotate with the sheet P sandwiched therebetween. The fixing device 12 sandwiches and heats and presses the sheet P with the toner image transferred therebetween, and fixes the toner image onto the sheet P. Although not shown, a heater as a heat source is disposed inside the fixing roller 31, and the heat generated by this heater heats the surface of the fixing roller 31 that contacts the sheet P with the toner image transferred thereon.

[0049] The paper feed cassette 18 is a cassette for storing the sheet P used for image formation, and is provided below the optical scanning device 1. The sheet P is pulled out from the paper feed cassette 18 by the pickup roller 16 and conveyed to the sheet conveyance path S. The sheet P conveyed to the sheet conveyance path S passes through the secondary transfer device 11 and the fixing device 12, is conveyed to the discharge roller 17, and is discharged to the sheet discharge tray 141 in the discharge unit 140. In the sheet conveyance path S, a conveyance roller 13, a registration roller 14, and a discharge roller 17 are arranged. The conveyance roller 13 promotes the conveyance of the sheet P. The registration roller 14 temporarily stops the sheet P and aligns the leading edges of the sheet P. Further, the registration roller 14 conveys the temporarily stopped sheet P in accordance with the timing of the color toner image on the intermediate transfer belt 71. The color toner image on the intermediate transfer belt 71 is transferred to the sheet P in the transfer nip region TN between the intermediate transfer belt 71 and the secondary transfer roller 11a.

[0050] In addition, in FIG. 1, one paper feed cassette 18 is shown, but the present invention is not limited to this, and a configuration in which a plurality of paper feed cassettes 18 are provided may be adopted, and different types of sheets P may be loaded in each of them.

[0051] Further, when the image forming apparatus 100 forms an image not only on the front surface of the sheet P but also on the back surface, the sheet P is conveyed in the reverse direction from the discharge roller 17 to the sheet inversion path Sr. The image forming apparatus 100 inverts the front and back of the sheet P conveyed in the reverse direction and guides it to the registration roller 14 again. Further, the image forming apparatus 100 forms an image on the back surface of the sheet P guided to the registration roller 14 in the same manner as the front surface and discharges it to the sheet discharge tray 141.

[0052] Next, the details of the configuration of the document feeder 160 will be described with reference to the drawings. FIG. 2 is a front view schematically showing a perspective view of the configuration of the document feeder according to the embodiment of the present disclosure. FIG. 3 is a perspective view showing a schematic internal configuration of the document feeder according to the embodiment of the present disclosure. FIG. 4 is an enlarged perspective view schematically showing the arrangement of gears for driving each roller of the document feeder according to the embodiment of the present disclosure.

[0053] Note that FIG. 3 is a view showing a state in which the upper cover of the document feeder 160 is removed and the conveyance path of the document G is exposed. Further, FIG. 4 is an enlarged view showing a state in which the upper cover of the document feeder 160 is removed and the first to fourth gears H1 to H4 are exposed. Furthermore, in FIG. 4, illustration of members such as the motor 27 is omitted so that the arrangement of the first to fourth gears H1 to H4 can be easily seen.

[0054] The document feeder 160 has been described above, and will be described in more detail. As shown in FIG. 2, the document feeder 160 includes a document pickup roller 22, a document feed roller 21, a second belt B2 stretched between these to connect and rotate the document feed roller 21 and the document pickup roller 22 together, a separation pad 23 disposed facing and adjacent to the document feed roller 21, a large-diameter conveyance roller 24, a driven roller 25 disposed facing and adjacent to the large-diameter conveyance roller 24, a second document reading unit 132b for reading the back side of the document G, and a pair of document discharge rollers 26 disposed facing and pressing against each other to discharge the document G to the outside. Further, the document feeder 160 has a document conveyance path L which is a path along which the document G is conveyed. Specifically, the document G is discharged from the document placement tray 161 to the document discharge tray 162 through the document pickup roller 22, the document feed roller 21, the large-diameter conveyance roller 24 (driven roller 25), and the document discharge roller 26 in this order. Note that, as shown in FIGS. 3 and 4, two large-diameter conveyance rollers 24 are provided, and a driven roller 25 is disposed for each of them.

[0055] Here, the diameter of the large-diameter conveyance roller 24 is, for example, 28 mm, the diameter of the document feed roller 21 is, for example, 14 mm, and the large-diameter conveyance roller 24 has a larger diameter than the document feed roller 21. Also, the diameter of the driven roller 25 is, for example, 8 mm, and the large-diameter conveyance roller 24 has a larger diameter than the driven roller 25. Further, the conveyance speed of the document G by the large-diameter conveyance roller 24 is, for example, 208 mm / second, and the conveyance speed of the document G by the document feed roller 21 is, for example, 125 mm / second.

[0056] In the original document conveyance path L, the original document G is sent from the original document paper feed roller 21 to the large-diameter conveyance roller 24. Here, the original document conveyance path L has a portion that curves along the outer periphery of the large-diameter conveyance roller 24, and this curved portion is the curved conveyance path La. That is, the large-diameter conveyance roller 24 is provided inside the curved conveyance path La and is arranged along the inner periphery of the curved conveyance path La. The curved conveyance path La is, in other words, a U-shaped U-turn path.

[0057] The curved conveyance path La is a part of the original document conveyance path L. The original document G conveyed through the original document conveyance path L passes through the first original document reading position A1 and the second original document reading position A2 located on the downstream side in sequence after passing through the curved conveyance path La, and is discharged to the original document discharge tray 162 by the original document discharge roller 26. Here, the first original document reading position A1 is the location where the first original document reading unit 132a (see FIG. 1) is arranged. When the original document G passes through the first original document reading position A1, the front side of the original document G is read by the first original document reading unit 132a. Also, the second original document reading position A2 is the location where the second original document reading unit 132b is arranged. When the original document G passes through the second original document reading position A2, the back side of the original document G is read by the second original document reading unit 132b. Note that the second original document reading position A2 is on the side of the original document discharge roller 26 (the nip of the original document discharge roller 26) from the first original document reading position A1.

[0058] The conveyance process of the original document G in the original document conveyance path L will be described. First, the original document pickup roller 22 pulls out the original documents G stacked on the original document placement tray 161 one by one and sends them to the original document paper feed roller 21. The original document paper feed roller 21 sends the original documents G one by one to the large-diameter conveyance roller 24. That is, the original document paper feed roller 21 sends the original documents G one by one to the curved conveyance path La. Even if there are multiple original documents G pulled out by the original document pickup roller 22 or if the original documents G are continuously sent to the original document paper feed roller 21, since the separation pad 23 is provided, it is possible to suppress the situation where a plurality of original documents G are sent to the large-diameter conveyance roller 24 at once from the original document paper feed roller 21, and the original documents G are sent to the large-diameter conveyance roller 24 one by one.

[0059] In the curved conveyance path La, the document G is conveyed along the outer circumference of the large-diameter conveyance roller 24. Further, at the position where the driven roller 25 is arranged, the large-diameter conveyance roller 24 and the driven roller 25 convey the document G in a state where they sandwich the document G.

[0060] After the document G passes through the curved conveyance path La, it passes through the first document reading position A1, and further passes through the second document reading position A2 and is sent to the document discharge roller 26. The document G is conveyed while being sandwiched between a pair of document discharge rollers 26, and is discharged onto the document discharge tray 162.

[0061] In this way, the reason why the document G is conveyed along the document conveyance path L including the curved conveyance path La is that the document pickup roller 22, the document feeding roller 21, the large-diameter conveyance roller 24, and the document discharge roller 26 are rotationally driven. Also, the power sources for rotating these document pickup roller 22, document feeding roller 21, large-diameter conveyance roller 24, and document discharge roller 26 are the same (a single drive motor). Specifically, as shown in FIG. 3, the document feeding device 160 includes a motor 27, and when the motor 27 operates, its power is transmitted to the document pickup roller 22, the document feeding roller 21, the large-diameter conveyance roller 24, and the document discharge roller 26 via a transmission mechanism including a plurality of gears, causing them to be rotationally driven.

[0062] Regarding the document discharge roller 26, the power from the motor 27 is transmitted to one roller arranged on the upper side, causing this roller to be rotationally driven, and the other roller arranged on the lower side rotates (is driven to rotate passively) when the one roller is rotationally driven. Also, regarding the driven roller 25, it rotates (is driven to rotate passively) when the large-diameter conveyance roller 24 is rotationally driven.

[0063] Specifically, as shown in FIG. 4, the document feeder 160 includes a first gear H1, a second gear H2, a third gear H3, a gear H3a provided on the same rotation axis as the third gear H3, and a fourth gear H4. Further, as shown in FIG. 3, the document feeder 160 includes a fifth gear H5 and a sixth gear H6. Furthermore, the document feeder 160 includes a first belt B1 stretched between the fifth gear H5 and the sixth gear H6, and the above-described second belt B2 stretched between the document feed roller 21 and the document pickup roller 22.

[0064] The first gear H1 meshes with a gear (not shown) provided on the rotation axis of the motor 27, and the first gear H1 is rotationally driven when the motor 27 is rotationally driven.

[0065] The second gear H2 is provided on the rotation axis of the large-diameter conveyance roller 24. The second gear H2 meshes with a gear (not shown) provided on the rotation axis of the first gear H1, and is rotationally driven when the first gear H1 is rotationally driven. When the second gear H2 is rotationally driven, the large-diameter conveyance roller 24 is also rotationally driven. As described above, when the large-diameter conveyance roller 24 is rotationally driven, the driven roller 25 is also rotationally driven.

[0066] The third gear H3 meshes with a gear (not shown) provided on the rotation axis of the first gear H1, and is rotationally driven when the first gear H1 is rotationally driven.

[0067] The fourth gear H4 is provided on the rotation axis of the document feed roller 21. The fourth gear H4 meshes with the gear H3a provided on the rotation axis of the third gear H3, and is rotationally driven when the third gear H3 is rotationally driven. When the fourth gear H4 is rotationally driven, the document feed roller 21 is also rotationally driven.

[0068] Also, since the second belt B2 is stretched between the document feed roller 21 and the document pickup roller 22, when the document feed roller 21 is rotationally driven, power is transmitted to the document pickup roller 22 by the second belt B2, and the document pickup roller 22 is rotationally driven.

[0069] The fifth gear H5 is provided on the rotating shaft of the large-diameter conveying roller 24. When the large-diameter conveying roller 24 is rotationally driven, the fifth gear H5 is rotationally driven.

[0070] The sixth gear H6 is provided on the rotating shaft of the upper roller of the original paper discharge roller 26. When the sixth gear H6 is rotationally driven, the original paper discharge roller 26 is rotationally driven.

[0071] Also, since the first belt B1 is stretched over the fifth gear H5 and the sixth gear H6, when the large-diameter conveying roller 24 is rotationally driven, the fifth gear H5 is rotationally driven, and power is transmitted to the sixth gear H6 by the first belt B1, causing the sixth gear H6 to be rotationally driven. As a result, the original paper discharge roller 26 is rotationally driven.

[0072] In this way, when the single motor 27 is rotationally driven, the original paper pickup roller 22, the original paper feed roller 21, the large-diameter conveying roller 24, and the original paper discharge roller 26 are rotationally driven. Note that the rotational speeds of the respective rollers do not necessarily have to be the same, and the rotational speeds of the respective rollers are adjusted according to the configuration of each gear (for example, the gear ratio, etc.). As a result, in the original paper feeding device 160, there is no need to provide a device for switching the on / off of the drive connection such as a clutch solenoid, and the conveying speeds of the respective rollers can be adjusted as described above. Also, except during error occurrence, etc., the rotation of the motor 27 does not stop during the conveying operation of the original paper G. As a result, the control is easy. Furthermore, the number of parts can be reduced, and the manufacturing cost can be suppressed.

[0073] Here, the rotation speeds of the document feed roller 21 and the large-diameter conveyance roller 24 are adjusted so that the conveyance speed of the document G by the document feed roller 21 is slower than the conveyance speed of the large-diameter conveyance roller 24. That is, the conveyance speed of the large-diameter conveyance roller 24 is greater than the conveyance speed of the document feed roller 21. Thereby, it is possible to sufficiently provide a distance between sheets of each document G when feeding a plurality of documents G. Further, in the curved conveyance path La, since the conveyance is assisted by the large-diameter conveyance roller 24, when the document G is conveyed in the document conveyance path L, conveyance defects such as the document being conveyed in an inclined state or a conveyance jam occurring can be suppressed.

[0074] Note that by sufficiently securing the distance between sheets, when it is necessary to stop the document conveyance operation midway, such as when the supplied document G is insufficient during the document conveyance operation in the document feeding device 160, the document conveyance operation can be stopped without waste.

[0075] Also, between the document feed roller 21 disposed upstream of the large-diameter conveyance roller 24 in the document conveyance path L and the first document reading position A1 disposed downstream of the large-diameter conveyance roller 24, a driven roller 25 is disposed closer to the first document reading position A1 than the document feed roller 21. Thereby, when continuously conveying the document G, it is possible to sufficiently secure the distance between sheets between the first document G and the second document G. Here, by disposing the driven roller 25 closer to the first document reading position A1 than the document feed roller 21, until the leading end of the document G enters the nip between the large-diameter conveyance roller 24 and the driven roller 25, the document G is conveyed by the document feed roller 21, resulting in unstable conveyance. However, since the large-diameter conveyance roller 24 having a relatively large diameter is disposed, the resistance when the document G passes through the curved conveyance path La can be reduced by the rotational action of the large-diameter conveyance roller 24 (by the conveyance guide forming the document conveyance path L and the large-diameter conveyance roller 24). Thereby, when the document G is conveyed in the document conveyance path L, conveyance defects such as the document being conveyed in an inclined state or a conveyance jam occurring can be suppressed.

[0076] Also, in the document conveyance path L of the document feeder 160, since no roller for conveying the document G other than the large-diameter conveyance roller 24 is arranged between the document feed roller 21 and the driven roller 25, the number of components can be reduced and the manufacturing cost can be suppressed. And, since it has the large-diameter conveyance roller 24, the document G can be stably conveyed even with such a configuration.

[0077] Also, in the document conveyance path L of the document feeder 160, it is preferable that no roller for conveying the document G is arranged between the driven roller 25 and the document discharge roller 26. Thereby, the number of components can be reduced and the manufacturing cost can be suppressed.

[0078] As described above, the configuration of the image forming apparatus 100 according to the present embodiment has been described. Next, the operation of conveying the document G in the document conveyance path L of the document feeder 160 of the image forming apparatus 100 will be described with reference to the drawings.

[0079] FIG. 5 is a first state diagram showing the document conveyance operation of the document feeder according to the embodiment of the present disclosure. FIG. 6 is a second state diagram showing the document conveyance operation of the document feeder according to the embodiment of the present disclosure. FIG. 7 is a third state diagram showing the document conveyance operation of the document feeder according to the embodiment of the present disclosure. FIG. 8 is a fourth state diagram showing the document conveyance operation of the document feeder according to the embodiment of the present disclosure. FIG. 9 is a fifth state diagram showing the document conveyance operation of the document feeder according to the embodiment of the present disclosure.

[0080] FIGS. 5 to 9 sequentially show the operation in which two documents G (document G1, document G2) stacked on the document placement tray 161 are conveyed along the document conveyance path L and discharged to the outside by the document discharge roller 26.

[0081] First, as shown in FIG. 5, the original documents G1 and G2 are stacked on the original document placement tray 161. Note that the original document G1 is placed on top of the original document G2, and the original document feeder 160 operates from this state. The original document pickup roller 22 is normally above the position shown in FIG. 5 and descends downward to contact the original document G1 in order to perform the conveyance operation. That is, for example, when the original document feeder 160 operates due to the copy execution key being turned on or the like, the original document pickup roller 22 descends.

[0082] When the motor 27 rotates and drives, and the power is transmitted to the original document pickup roller 22, the original document pickup roller 22 rotates and drives. As shown in FIG. 6, the original document G1 is pulled out from the original document placement tray 161. When the motor 27 rotates and drives, in addition to the original document pickup roller 22, the original document paper feed roller 21, the large-diameter conveyance roller 24, and the original document discharge roller 26 also rotate and drive.

[0083] The original document G1 pulled out from the original document placement tray 161 by the original document pickup roller 22 is sent to the original document paper feed roller 21, and further sent to the large-diameter conveyance roller 24 by the original document paper feed roller 21. At this time, the original document G1 is conveyed through the curved conveyance path La. Until the leading edge of the original document G1 reaches the position of the driven roller 25, the original document G1 is conveyed by the original document paper feed roller 21, and the conveyance speed thereof is the conveyance speed of the original document paper feed roller 21. The original document G1 is conveyed at a conveyance speed of, for example, 125 mm / second. Also, at this time, due to the rotational action of the large-diameter conveyance roller 24, the conveyance of the original document G1 is stable.

[0084] As shown in FIG. 7, when the original document G1 conveyed through the curved conveyance path La approaches the position of the driven roller 25, it is sandwiched and conveyed by the large-diameter conveyance roller 24 and the driven roller 25. As a result, the original document G1 is conveyed at the conveyance speed of the large-diameter conveyance roller 24, and the original document G1 is conveyed at a conveyance speed of, for example, 208 mm / second. That is, the conveyance speed increases.

[0085] As shown in FIG. 8, the original document G1 is conveyed by the large-diameter conveyance roller 24 and the driven roller 25, and passes through the first original document reading position A1 and the second original document reading position A2 in the original document conveyance path L. At this time, the front side of the original document G1 is read by the first original document reading unit 132a (see FIG. 1). Also, the back side of the original document G1 is read by the second original document reading unit 132b.

[0086] Also, the original document G2 pulled out from the original document placement tray 161 by the original document pickup roller 22 is sent to the original document paper feed roller 21. As described above, since the conveyance speed of the large-diameter conveyance roller 24 is greater than the conveyance speed of the original document paper feed roller 21, in this state, the conveyance speed of the original document G1 is greater than the conveyance speed of the original document G2, and a sufficient paper distance between the original document G1 and the original document G2 is ensured, and stable conveyance is performed.

[0087] As shown in FIG. 9, the original document G1 is sent to the original document discharge roller 26 and conveyed by the original document discharge roller 26. After that, the original document G1 is discharged to the outside (original document discharge tray 162).

[0088] Also, the original document G2 pulled out from the original document placement tray 161 by the original document pickup roller 22 is sent to the original document paper feed roller 21 in the same manner as the original document G1, and further sent to the large-diameter conveyance roller 24 by the original document paper feed roller 21 and conveyed through the curved conveyance path La. At this time, the conveyance of the original document G2 is by the original document paper feed roller 21, and the conveyance speed is that of the original document paper feed roller 21. Also, when the original document G2 approaches the position of the driven roller 25, it is sandwiched and conveyed by the large-diameter conveyance roller 24 and the driven roller 25. At this time, the conveyance of the original document G2 is by the large-diameter conveyance roller 24, and the conveyance speed is that of the large-diameter conveyance roller 24. And although not shown in the figure, the original document G2 is also conveyed by the original document discharge roller 26 and discharged to the outside in the same manner as the original document G1. Although the state where two original documents G are stacked on the original document placement tray 161 has been described, the conveyance operation is performed in the same manner even if the number of stacked original documents G is other than two. In the state shown in FIG. 9, the paper distance between the original document G1 and the original document G2 is, for example, 80 mm.

[0089] The above describes the image forming apparatus 100 and the document feeder 160 according to the present embodiment. As described above, according to the document feeder 160, since the conveyance speed of the document G by the large-diameter conveyance roller 24 is greater than the conveyance speed of the document G by the document feed roller 21, a sufficient inter-sheet distance between the documents G can be ensured. Further, since the large-diameter conveyance roller 24 having an outer circumference along the inner circumference of the curved conveyance path La is disposed inside the curved conveyance path La, it is possible to suppress instability in the conveyance of the document G in the document conveyance path L and to suppress the occurrence of problems such as skewed paper feeding and conveyance jams. (Other Embodiments) In the above-described present embodiment, the document feeder 160 is configured to have two large-diameter conveyance rollers 24, but the large-diameter conveyance roller 24 may be one. For example, it may be configured to have a large-diameter conveyance roller 24 having a shape extending in the axial direction so that the document G can be stably conveyed.

[0090] According to the document feeder 160 and the image forming apparatus 100 including the same described above, it is possible to ensure the inter-sheet space of the document G being conveyed with an inexpensive configuration, and by the rotational action of the large-diameter conveyance roller 24, it is possible to reduce the resistance during conveyance in the curved conveyance path La and to stably convey the document G. Thereby, it is possible to suppress the occurrence of problems in the conveyance of the document G such as skewed paper feeding and conveyance jams. Further, since the number of components is small and it can be realized with a simple configuration, the manufacturing cost can be suppressed.

[0091] The present disclosure is not limited to the embodiments described above, and can be implemented in various other forms. Therefore, such embodiments are merely illustrative in all respects and should not be construed in a limiting sense. The scope of the present disclosure is indicated by the claims and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present disclosure.

Description of Reference Numerals

[0092] 1 Optical Scanning Device 2 Developing Device 3 Photoconductor drum 4 Drum cleaning device 5 Charger 6 Intermediate transfer roller 9 Cleaning device 11 Secondary transfer device 11a Secondary transfer roller 12 Fixing device 13 Conveyor roller 14 Resist roller 16 Pickup roller 17 Discharge roller 18 Paper feed cassette 21 Original paper feed roller 22 Original paper pickup roller 23 Separation pad 24 Large-diameter conveyor roller 24a Rotating shaft 25 Driven roller 26 Original paper discharge roller 27 Motor 31 Fixing roller 32 Pressure roller 70 Intermediate transfer belt device 71 Intermediate transfer belt 72 Intermediate transfer drive roller 73 Intermediate transfer driven roller 100 Image forming device 101 Image forming device main body 102 Image reading device 130 Reading section 130a Original paper placement table 132a First original paper reading section 132b Second original paper reading section 131 Scanning optical system 140 Discharge section 141 Sheet discharge tray 160 Original paper feeding device 161 Original paper placement tray 162 Original paper discharge tray A1 First original paper reading position A2 Second original paper reading position B1 First belt B2 Second belt Original manuscripts G, G1, G2 Gears H1 to H6, gears 1 to 6 Gear H3a Original manuscript conveyance path L Curved conveyance path La Sheet P Image stations Pa, Pb, Pc, Pd Sheet conveyance path S Sheet reversal path Sr Transfer nip region TN

Claims

1. A document feeder having a document conveyance path for conveying a document to a document reading position for reading an image, wherein the document conveyance path includes a curved conveyance path, a sheet feeding roller for feeding the document to the curved conveyance path, and a large-diameter conveyance roller disposed inside the curved conveyance path and having a diameter larger than that of the sheet feeding roller, wherein a document conveyance speed by the large-diameter conveyance roller is larger than a document conveyance speed by the sheet feeding roller, the document feeder being characterized by this.

2. The document feeder according to claim 1, comprising a single driven roller that is in pressure contact with the large-diameter conveyance roller and rotates therewith, wherein the document reading position is disposed downstream of the large-diameter conveyance roller, and the driven roller is disposed between the sheet feeding roller disposed upstream of the large-diameter conveyance roller in the document conveyance path and the document reading position, and is disposed closer to the document reading position than the sheet feeding roller, the document feeder being characterized by this.

3. The document feeder according to claim 1, comprising a paper discharge roller disposed downstream of the large-diameter conveyance roller and discharging the document read at the document reading position to the outside, wherein the sheet feeding roller, the large-diameter conveyance roller, and the paper discharge roller are rotationally driven by the same motor, the document feeder being characterized by this.

4. The document feeder according to claim 3, wherein each of the sheet feeding roller, the large-diameter conveyance roller, and the paper discharge roller is connected to the motor by a transmission mechanism including gears, the document feeder being characterized by this.

5. The document feeder according to claim 2, In the original document conveyance path, no conveyance roller other than the large-diameter conveyance roller is disposed between the paper feed roller and the driven roller. A document feeding device characterized by this.

6. The document feeding device according to claim 2, wherein the driven roller is disposed below a horizontal plane including a rotation axis of the large-diameter conveyance roller. A document feeding device characterized by this.

7. The document feeding device according to claim 2, comprising a paper discharge roller disposed downstream of the large-diameter conveyance roller and discharging the document read at the document reading position to the outside, wherein the document reading position includes a first document reading position for reading one side of the document and a second document reading position for reading the other side of the document, and is located downstream of the first document reading position in the document conveyance path, and the second document reading position is closer to the paper discharge roller than the first document reading position. A document feeding device characterized by this.

8. The document feeding device according to claim 3, wherein during the document feeding operation, the motor does not stop except when an error occurs. A document feeding device characterized by this.

9. The document feeding device according to claim 2, comprising a paper discharge roller disposed downstream of the large-diameter conveyance roller and discharging the document read at the document reading position to the outside, wherein no roller for conveying the document is provided between the driven roller and the paper discharge roller. A document feeding device characterized by this.

10. An image forming apparatus comprising the document feeding device according to any one of claims 1 to 9.

Images