Sheet transport device and image forming apparatus

Abstract

Even if the leading edge of a sheet transported by the conveying mechanism becomes wavy, this easily mitigates the problem of the sheet jamming at the guide member. [Solution] The guide member 31 that guides the sheet P conveyed by the feed roller 17 to the downstream side in the conveying direction is provided with a reference guide surface 31a that extends along the conveying direction and a recess 31b that is recessed in the retraction direction away from the sheet conveying path relative to the reference guide surface 31a. The recess 31b has a corner portion 31c that connects to the reference guide surface 31a in the downstream side in the conveying direction, extending from the most recessed top portion 31e in the retraction direction. Furthermore, the recess 31b is inclined toward the downstream side in the conveying direction and also inclined toward the outside in the width direction perpendicular to the conveying direction within the plane of the reference guide surface 31a, and a pair of inclined surfaces 31d that connect to the reference guide surface 31a are arranged so as to sandwich the corner portion 31c.

Description

Technical Field

[0001] The present invention relates to a sheet conveying device that conveys a sheet such as paper, and an image forming apparatus including the same, such as a copying machine, a printer, a facsimile machine, a multifunction peripheral or a printing machine combining the foregoing. Background Art

[0002] Conventionally, in sheet conveying devices installed in image forming apparatuses such as copying machines, printers, and printing machines, it has been widely known that a guide member (conveying guide plate) that guides a sheet conveyed by a conveying means such as a feeding roller to the downstream side in the sheet conveying direction is provided (see, for example, Patent Document 1).

[0003] On the other hand, Patent Document 1 discloses a technique for preventing a problem that a sheet conveyed by a sheet feeding roller (conveying means) is curled and jams (paper jam) at the position of the guide member, in which the sheet feeding roller is rotated in forward and reverse directions to bring the curled portion into contact with the guide member, or a curl correcting lever is brought into sliding contact with the curled portion at a speed higher than the sheet conveying speed. Summary of the Invention Problem to be Solved by the Invention

[0004] In a conventional sheet conveying device, when waving occurs at the leading end of a sheet conveyed by the conveying means, the waved portion (waving part) rides onto the guide member or buckles, which may cause the sheet to jam. In response to this, applying the technique of Patent Document 1, measures such as making the conveying direction of the sheet by the conveying means variable in forward and reverse directions, or providing a correction lever for correcting the waved portion of the sheet can be considered. However, in this case, problems such as complicated control and configuration, reduced productivity of sheet conveyance, increased size and higher cost of the apparatus will occur.

[0005] This invention was made to solve the above-mentioned problems, and aims to provide a sheet conveying device and an image forming apparatus that can easily reduce the problem of a sheet jamming at the position of a guide member, even if the leading edge of the sheet conveyed by the conveying means becomes wavy. [Means for solving the problem]

[0006] The sheet conveying device in this invention comprises a conveying means for conveying a sheet, and a guide member for guiding the sheet conveyed by the conveying means to the downstream side in the conveying direction, wherein the guide member comprises a reference guide surface extending along the conveying direction, and a recess recessed in a retraction direction away from the sheet conveying path relative to the reference guide surface, wherein the recess has a corner portion connected to the reference guide surface toward the downstream side in the conveying direction from the most recessed apex in the retraction direction, and a pair of inclined surfaces arranged to sandwich the corner portion, inclined toward the downstream side in the conveying direction, and inclined toward the outside in the width direction perpendicular to the conveying direction within the plane of the reference guide surface, and connected to the reference guide surface. [Effects of the Invention]

[0007] According to the present invention, even if the leading edge of a sheet conveyed by a conveying means becomes wavy, the problem of the sheet jamming at the position of the guide member can be easily reduced. This provides a sheet conveying device and an image forming apparatus. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing the configuration of a sheet conveying device. [Figure 3] This is a perspective view showing a part of a sheet conveying device. [Figure 4] This is a perspective view showing the main part of the upper guide member. [Figure 5]This is a perspective view showing the wavy sheet in contact with the upper guide member. [Figure 6] This diagram shows the trajectory of the wavy sheet as it is transported to the position of the upper guide member. [Figure 7] This is a perspective view showing the movement of a wavy sheet being transported downstream from the position of the upper guide member. [Figure 8] This is a side view showing the trajectory of the wavy sheet as it is transported downstream from the position of the upper guide member. [Figure 9] This diagram shows the positional relationship between the upper guide member and the feed roller in the width direction. [Figure 10] This is a perspective view from the side of the guide member showing that the sheet fed from the manual feed tray is wavy. [Figure 11] This is a perspective view showing the operation of a wavy sheet being transported to the position of the upper guide member, as a comparative example. [Figure 12] This figure shows the trajectory of the wavy sheet as it is transported to the position of the upper guide member in Figure 11. [Figure 13] This is a perspective view showing the upper guide member as an example of modification 1. [Figure 14] This is a perspective view showing the upper guide member as a modified example 2. [Figure 15] This is a perspective view showing the upper guide member as a modified example 3. [Figure 16] This figure shows the positional relationship in the width direction between the upper guide member and the feed roller, as a modified example (modification 4). [Figure 17] This diagram shows the positional relationship in the width direction between the upper guide member and the feed roller, as a modified example (5). [Figure 18] This figure shows a sheet conveying device as an example of modification 6. [Modes for carrying out the invention]

[0009] Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings. In each drawing, identical or corresponding parts are denoted by identical reference signs, and duplicate description thereof will be appropriately simplified or omitted.

[0010] First, the overall configuration and operation of the image forming apparatus 1 will be described with reference to FIG. 1. In FIG. 1, 1 denotes a copying machine serving as an image forming apparatus, 2 denotes an original reading section that optically reads image information of an original, 3 denotes an exposure section that irradiates exposure light L based on the image information read by the original reading section 2 onto a photosensitive drum 5, 4 denotes an image forming section that forms a toner image (image) on the photosensitive drum 5, and 7 denotes a transfer section (image forming section) that transfers the toner image formed on the photosensitive drum 5 onto a sheet P (sheet). Further, 10 denotes an original conveying section (automatic original conveying device) that conveys an original set on an original platen to the original reading section 2, 13 denotes a feeding cassette (feeding device) that stores sheets P, and 15 denotes a manual feeding device serving as a sheet conveying device that feeds a sheet P set by a user on a manual tray 16. Further, 20 denotes a fixing device that fixes a toner image (unfixed image) carried on the sheet P, 21 denotes a fixing roller provided in the fixing device 20, 22 denotes a pressure roller provided in the fixing device 20, 30 and 35 denote pairs of conveying rollers that convey the sheet P along a sheet conveying path, 52 denotes a feeding mechanism that feeds the sheet P provided in the feeding cassette 13, and 90 denotes a paper discharge tray on which sheets P discharged from the apparatus main body 1 are stacked. The manual feeding device 15 is configured of the manual tray 16, a feeding roller 17, a separation pad 18, the pair of conveying rollers 30, and the like. Further, the feeding mechanism 52 is configured of a pickup roller 54, a feeding roller 53, a separation roller 55, and the like.

[0011] With reference to FIG. 1, the operation during normal image formation in the image forming apparatus main body 1 will be described. First, an original set on the original platen is conveyed (fed) by the original conveying section 10, and passes over the original reading section 2. At this time, in the original reading section 2, image information of the original passing above is optically read. Then, after the optical image information read by the document reading unit 2 is converted into an electrical signal, it is transmitted to an exposure unit 3 (writing unit). Then, from the exposure unit 3, exposure light L such as a laser beam based on the image information of the electrical signal is emitted toward the photosensitive drum 5 of the image forming unit 4.

[0012] On the other hand, in the image forming unit 4, the photosensitive drum 5 rotates clockwise in the figure, and after going through predetermined image forming processes (charging step, exposure step, developing step), an image (toner image) corresponding to the image information is formed on the photosensitive drum 5. Thereafter, the image formed on the photosensitive drum 5 is transferred onto the sheet P conveyed by the registration roller 6 at a transfer unit 7 serving as an image forming unit.

[0013] On the other hand, the sheet P conveyed to the transfer unit 7 (image forming unit) operates as follows. First, the topmost sheet P stored in the paper feed cassette 13 is fed by the feeding mechanism 52 and conveyed toward the sheet conveying path. Thereafter, the sheet P passes through the sheet conveying path provided with a plurality of pairs of conveying rollers and reaches the position of the registration rollers 6. When the manual feeding device 15 installed on the side of the image forming apparatus main body 1 is selected, the sheet P placed on the manual feed tray 16 of the manual feeding device 15 by the user (when a plurality of sheets P are stacked, it refers to the topmost sheet P) is fed toward the sheet conveying path by the feeding roller 17 (conveying means) and reaches the position of the registration rollers 6.

[0014] The sheet P that has reached the position of the registration rollers 6 is conveyed toward the transfer unit 7 (image forming unit) at a timing adjusted for alignment with the image formed on the photosensitive drum 5. After the transfer process, the sheet P passes through the transfer section 7 and then travels along the sheet transport path to reach the fixing device 20. Upon reaching the fixing device 20, the sheet P is fed between the fixing roller 21 and the pressure roller 22, where the toner image is fixed by the heat received from the fixing roller 21 and the pressure received from both components 21 and 22 (this is the fixing process). After the fixing process, the sheet P with the fixed toner image is fed out from between the fixing roller 21 and the pressure roller 22 (this is the fixing nip), then discharged from the image forming apparatus body 1, and loaded onto the output tray 31 as the output image. Thus, the series of image formation processes is completed.

[0015] Next, using Figures 2 to 10, the manual feeding device 15, which is a characteristic sheet conveying device in this embodiment, will be described in detail. Referring to Figures 2 and 3, the manual feed device 15, which serves as a sheet conveying device in this embodiment, consists of a manual feed tray 16, conveying means 17 to 19, an upper guide member 31 and a lower guide member 32 as guide members, and a pair of conveying rollers 30.

[0016] The conveying means conveys the sheet P that has been manually fed into the manual feed tray 16, and consists of a feed roller 17 (feed roller) that is driven to rotate counterclockwise in Figure 2 by a drive mechanism (not shown), a separation pad 18 as a separation member that contacts the feed roller 17, and a compression spring (biasing member) that biases the separation pad 18 in the direction that it contacts the feed roller 17. In this embodiment, the feed roller 17 (and the separation pad 18) is positioned in the center in the width direction (the direction perpendicular to the plane of the paper in Figure 2), and is configured to transport the sheet P set in the manual feed tray 16 without skew, using the center as a reference. By bringing the separation pad 18 into contact with the feed roller 17 to form a nip, the problem of two or more sheets P being fed (double-feeded) from the position of the nip is suppressed. In this embodiment, the sheet P is set in the manual feed tray 16 such that its leading edge bites into the nip between the feed roller 17 and the separation pad 18. Furthermore, the orientation (position) of the sheet P set in the manual feed tray 16 in the width direction (the direction perpendicular to the paper plane in Figure 2) is determined by a pair of side fences 16a (see Figures 2 and 3).

[0017] Both the upper guide member 31 and the lower guide member 32 function as guide members that guide the sheet P, which has been conveyed by the feed roller 17 (conveying means), to the downstream side in the conveying direction (the direction indicated by arrow K in Figure 6). The upper guide member 31 is positioned to face the front surface of the sheet P, and the lower guide member 32 is positioned to face the back surface of the sheet P, with a sheet transport path formed in the space between the two guide members 31 facing each other. Further downstream in the transport direction from the guide members 31 and 32, a pair of transport rollers 30 is provided to transport the sheet P further downstream in the transport direction.

[0018] In particular, in this embodiment, as shown in Figure 6, the tangential direction of the feeding roller 17 (indicated by the arrow in thick line in Figure 6) passing through the nip between the feeding roller 17 and the separation pad 18 is approximately horizontal, whereas the conveying direction of the sheet conveying path by the guide members 31 and 32 (arrow K) is inclined downward from the upstream side to the downstream side. Therefore, the sheet P delivered from the nip between the feeding roller 17 and the separation pad 18 comes into contact with the upper guide member 31 and is then guided along the inclined surface of the upper guide member 31 (which will be described later as the reference guide surface 31a).

[0019] Referring to Figures 4 and 6, the upper guide member 31, which serves as a guide member in this embodiment, is provided with a reference guide surface 31a and a recess 31b. The reference guide surface 31a is a plane that extends along the transport direction (arrow K) described above. The sheet P, transported by the feed roller 17 (conveying means), is transported (guided) along the reference guide surface 31a of the upper guide member 31. However, in this embodiment, in order to reduce the transport load (frictional resistance) caused by the sheet P sliding against the reference guide surface 31a, a plurality of ribs 31x are arranged in parallel on the reference guide surface 31a at intervals in the width direction (arrow W) so as to extend in the transport direction. In this embodiment, the reference guide surface 31a is a flat surface, but it can also be a curved surface. Furthermore, if the surface friction coefficient of the reference guide surface 31a is set to a small value, the installation of multiple ribs 31x can be omitted.

[0020] Referring to Figures 4 and 6, the recess 31b is a portion that is recessed in a roughly triangular pyramidal shape relative to the reference guide surface 31a in the retraction direction away from the sheet transport path (the sheet transport path formed by guide members 31 and 32). In other words, the upper guide member 31 has the recess 31b recessed in a direction (retraction direction) relative to the reference guide surface 31a so as not to protrude into the sheet transport path. In the present embodiment, the recess 31b is formed in the center of the upper guide member 31 in the width direction.

[0021] As shown in Figure 4, the recess 31b has a corner portion 31c that connects to the reference guide surface 31a, extending downstream in the transport direction (arrow K) from the most recessed top portion 31e in the retraction direction. Furthermore, the recess 31b is inclined toward the downstream in the transport direction, and within the plane of the reference guide surface 31a, it is inclined toward the outside in the width direction (arrow W) perpendicular to the transport direction, and a pair of inclined surfaces 31d that connect to the reference guide surface 31a are arranged so as to sandwich the corner portion 31c. In particular, the upper guide member 31 (guide member) in this embodiment has a corner portion 31c that is angular. That is, the corner portion 31c is formed as a ridge. Therefore, in this embodiment, the recess 31b is inclined toward the downstream side in the transport direction K, with the ridge (corner portion 31c) connecting to the reference guide surface 31a as one side, from the most recessed top portion 31e in the retraction direction toward the downstream side in the transport direction K, and also inclined toward the outside in the width direction within the plane of the reference guide surface 31a, so that a pair of inclined surfaces 31d connecting to the reference guide surface 31a are formed so as to sandwich the ridge (corner portion 31c).

[0022] In other words, the corner 31c of the recess 31b is positioned such that its downstream end in the transport direction is in the same plane as the reference guide surface 31a, and its upstream end, the top 31e, is positioned as far back from the reference guide surface 31a as possible. Of the pair of inclined surfaces, the inclined surface 31d located on one end in the width direction relative to the corner 31c (right side in Figure 4) is formed such that, with the corner 31c as one side, it approaches the same plane as the reference guide surface 31a as it moves toward the other end in the width direction and toward the downstream side in the transport direction. Similarly, of the pair of inclined surfaces, the inclined surface 31d located on the other end in the width direction relative to the corner 31c (left side in Figure 4) is also formed such that, with the corner 31c as one side, it approaches the same plane as the reference guide surface 31a as it moves toward the other end in the width direction and toward the downstream side in the transport direction. The portion where the reference guide surface 31a and the inclined surface 31d connect is formed as a curved surface 31d1, which will be explained in detail later.

[0023] To put it another way, the recess 31b is inclined toward the downstream side in the transport direction, with the most recessed top portion 31e in the retraction direction in between, and is also inclined toward the outward side in the width direction within the plane of the reference guide surface 31a, forming a pair of inclined surfaces 31d that connect to the reference guide surface 31a.

[0024] In particular, as shown in Figure 5, etc., in the upper guide member 31 of this embodiment, the top portion 31e of the recess 31b (see Figure 4) is set so that its position in the width direction (left-right direction in Figure 5) substantially coincides with the center position in the width direction of the wavy portion Px that occurs in the sheet P conveyed by the feed roller 17 (conveying means). As shown in Figure 10, since the feed roller 17 is installed in the center in the width direction, the sheet P fed by the feed roller 17 experiences a difference in frictional resistance between the part that directly contacts the feed roller 17 and the part that does not directly contact the feed roller 17. As a result, the former part (especially the leading edge of the sheet) tends to become wavy (curved in a wavy shape) (wavy portion Px is easily formed). In this embodiment, the reference guide surface 31a of the upper guide member 31 has a recess 31b formed at a position corresponding to such wavy portion Px of the sheet P.

[0025] As described above, in this embodiment, the manual feeding device 15 (sheet conveying device) has a recess 31b that is recessed in a roughly triangular pyramidal shape relative to the reference guide surface 31a, and is formed such that it approaches the same plane as the reference guide surface 31a as it moves toward both ends in the width direction and toward the downstream side in the conveying direction. Therefore, even if the leading edge (leading edge in the conveying direction) of the sheet P conveyed by the feeding roller 17 (conveying means) becomes wavy (a wavy portion Px is formed), the problem of the sheet P getting jammed at the position of the upper guide member 31 can be reduced. In other words, as shown in the comparative example Figures 11 and 12, if no recess is formed on the reference guide surface 131a, the wavy portion Px of the sheet P is prone to riding up onto or getting caught on the upper guide member 131 and buckling, as shown in Figure 11(B) and Figure 12 (dashed arrows showing the trajectory of the wavy portion Px), which can cause the sheet P to jam (paper jam). Hereafter, such a problem will be referred to as "guide out". To prevent such "guide-out" occurrences, one possible measure is to extend the upper end (upstream end in the conveying direction) of the reference guide surface 131a upward. However, in that case, the upper guide member 131 would become larger and more expensive, or there would be limitations to this measure if there are constraints on the installation space of the upper guide member 131 (it would interfere with the feed roller 17). Another possible measure to prevent "guide-out" is to move the reference guide surface 131a away from the nip of the feed roller 17. However, in that case, if the angle between the leading edge of the sheet P and the upper guide member 131 becomes large, the transport load will increase, making the sheet P more prone to buckling, or the transport force from the feed roller 17 will be insufficient. On the other hand, if the angle between the leading edge of the sheet P and the upper guide member 131 becomes small, the installation space for the upper guide member 131 will be more restricted. Furthermore, measures such as varying the direction of sheet P transport by the feed roller 17 in forward and reverse directions, or installing a straightening lever to correct the wavy portion Px of sheet P, can also be considered. However, in that case, problems such as increased complexity of control and configuration, decreased productivity of sheet transport, and increased size and cost of the equipment would arise.

[0026] In contrast, in this embodiment, without incorporating the various measures described above, the occurrence of "guide-out" can be easily reduced simply by forming a recess 31b in the upper guide member 31. Furthermore, by having the wavy portion Px of the sheet P slide against the inclined surface 31d of the recess 31b, or slide against the portion where the inclined surface 31d and the reference guide surface 31a meet, the transport load of the sheet P can be reduced compared to when the wavy portion Px slides against a guide surface where the recess 31b is not provided (a guide surface that extends to a position including the corner portion 31c in this embodiment and has a flat surface across its entire surface). Therefore, even if a wavy portion Px is formed at the leading edge of the sheet P conveyed by the feed roller 17 (conveying means), the problem of the sheet P jamming at the position of the upper guide member 31 (guide member) is easily reduced, enabling smooth conveying with a low conveying load.

[0027] As shown in Figure 5, when the leading edge of the sheet P conveyed by the feed roller 17 reaches the position of the upper guide member 31, the portion other than the wavy portion Px contacts the reference guide surface 31a, but the wavy portion Px (especially the top portion) is in a position where it lightly contacts (or faces with a gap) the recess 31b and does not contact the reference guide surface 31a. Therefore, problems such as the wavy portion Px of the sheet P riding up onto or getting caught on the upper guide member 131 and buckling are less likely to occur. Furthermore, the inclined surface 31d of the recess 31b is formed such that it approaches the reference guide surface 31a as it moves toward the downstream side in the transport direction and toward both ends in the width direction, and finally merges with the reference guide surface 31a. As a result, the sheet P's undulations are scooped up by the inclined surface 31d, and it eventually becomes almost flat, following the reference guide surface 31a (the undulations disappear). This ensures that the sheet P, having passed through the guide members 31 and 32, is transported smoothly further downstream in the transport direction.

[0028] Here, as shown in Figure 9 and other figures, in this embodiment, the position of the top portion 31e (see Figure 4) of the recess 31b of the upper guide member 31 in the width direction (left-right direction in Figure 9) is set to substantially coincide with the center position in the width direction of the feed roller 17 (conveying means) (the position shown by the dashed line in Figure 9). With this configuration, even if a wavy portion Px is formed on the sheet P due to feeding by the feeding roller 17, the recess 31b effectively prevents the wavy portion Px from being guided out when the sheet P comes into contact with the upper guide member 31.

[0029] Furthermore, as explained earlier using Figure 4, in this embodiment, the upper guide member 31 (guide member) has a curved shape at the point where the reference guide surface 31a and the inclined surface 31d are connected. In other words, the point where the reference guide surface 31a and the inclined surface 31d connect is not a corner, but a gently curved surface 31d1 with rounded corners (a curved surface that curves convexly toward the side that guides the sheet P). By making the junction of the reference guide surface 31a and the inclined surface 31d a curved surface 31d1, it is possible to reduce the likelihood of problems such as the sheet P bouncing or the transport load on the sheet P increasing when the leading edge of the sheet P reaches that position. Furthermore, in order to fully realize such effects, it is preferable that the curved surface 31d1 be set so that its radius of curvature is 1 mm or more.

[0030] Furthermore, in this embodiment, the upper guide member 31 (guide member) is formed such that a pair of inclined surfaces 31d are symmetrical with respect to the corner portion 31c (see Figure 4). With this configuration, when the sheet P conveyed by the feed roller 17 passes over the recess 31b, the variation in the conveying load on the left and right sides of the corner 31c is reduced, making it less likely for the sheet P to skew.

[0031] The behavior of the wavy sheet P when it is transported downstream from the position of the upper guide member 31 will be explained below using Figures 7 and 8. As shown in Figures 7 and 8, as the wavy sheet P is transported downstream in the transport direction along the reference guide surface 31a (and recess 31b), the wavy portion Px is lifted towards the sheet transport path by the inclined surface 31d, and approaches a flat surface (the wavy shape is corrected). In this case, the junction of the inclined surface 31d and the reference guide surface 31a is a curved surface 31d1, which makes it less likely for the leading edge of the sheet P to bounce, and the transport load on the sheet P does not increase. Furthermore, since the inclined surface 31d is formed to gradually approach the reference guide surface 31a toward the downstream side in the conveying direction and both ends in the width direction, the sheet P is guided smoothly by the upper guide member 31 without getting caught, compared to the case where a sharp step is formed between the inclined surface 31d and the reference guide surface 31a.

[0032] <Example 1> As shown in Figure 13, in the modified example 1, the upper guide member 31 (guide member) has a pair of second reference guide surfaces 31f that are formed in a direction closer to the sheet transport path than the reference guide surface 31a, and these surfaces are formed to sandwich the reference guide surface 31a. In other words, the reference guide surface 31a is recessed in the retraction direction relative to the second reference guide surface 31f, and further recess 31b is formed in the retraction direction relative to the reference guide surface 31a. Furthermore, the reference guide surface 31a is formed such that as it moves downstream in the conveying direction, it approaches the same plane as the second reference guide surface 31f, and eventually connects to the second reference guide surface 31f. With this configuration, the upper guide member 31 has a recess 31b and a reference guide surface 31a formed in two stages to avoid interference with the wavy portion Px of the sheet P, further reducing the occurrence of "guide-out". This configuration is particularly useful when the width of the wavy portion Px is wide.

[0033] <Modification 2> As shown in Figure 14, in the modified example 2, the upper guide member 31 (guide member) has a curved corner portion 31c. In other words, the corner 31c is not angular (it does not form a ridge), but rather a gently curved surface with rounded corners (a curved surface that curves concavely on the side that guides sheet P). The dashed line Z shown in Figure 14 indicates the center position (virtual ridge) of the curved corner 31c. By making the corner 31c a curved surface in this way, it is possible to mitigate the damage that would occur if the sheet P came into contact with the corner 31c when its leading edge reached that position. Furthermore, even when the upper guide member 31 is configured in this way, if the leading edge of the sheet P conveyed by the feed roller 17 becomes wavy, the problem of the sheet P getting jammed at the position of the upper guide member 31 (guide member) can be easily mitigated.

[0034] <Variation 3> As shown in Figure 15, in the modified example 3, the upper guide member 31 (guide member) is not formed such that the pair of inclined surfaces 31d are symmetrical with respect to the corner 31c (it is formed asymmetrically). Such a configuration is useful when, due to the layout, it is not possible to arrange the pair of inclined surfaces 31da and 31db symmetrically around the corner 31c in order to install other components near the upper guide member 31. For example, this is useful when a hole is provided in the upper guide member 31 to avoid the optical path of an optical sensor for sheet detection. However, even when the upper guide member 31 is configured in this way, if the leading edge of the sheet P conveyed by the feed roller 17 becomes wavy, the problem of the sheet P getting jammed at the position of the upper guide member 31 (guide member) can be easily mitigated.

[0035] <Modification 4> As shown in Figure 16, in Modification 4, the manual feeding device 15 (sheet conveying device) has multiple feeding rollers (feeding rollers) as conveying means arranged in the width direction (left-right direction in Figure 16). Furthermore, the upper guide member 31 (guide member) has a recess 31b formed in it that corresponds to the position between adjacent feed rollers (conveying means) in the plurality of feed rollers (conveying means). More specifically, in Figure 16(A), two feed rollers 17A and 17B (conveying means) are arranged side by side with a gap between them on the rotating shaft, and are configured to rotate integrally by the drive of a drive mechanism (not shown). Furthermore, the upper guide member 31 has a recess 31b formed in a position corresponding to the space between the two feed rollers 17A and 17B. In particular, the position of the top 31e of the recess 31b of the upper guide member 31 in the width direction (the left-right direction in Figure 16(A)) is configured to substantially coincide with the central position between the two feed rollers 17A and 17B (conveying means) which are arranged side by side in the width direction (the position shown by the dashed line in Figure 16(A)). This configuration is useful when a conveying means uses two feed rollers 17A and 17B arranged side by side, and the wavy portion Px of the sheet P being fed is formed between the two feed rollers 17A and 17B. Furthermore, in such cases, even if the leading edge of the sheet P conveyed by the feed rollers 17A and 17B becomes wavy, a recess 31b is formed at the position of the upper guide member 31 corresponding to that position, thus easily mitigating the problem of the sheet P jamming at the position of the upper guide member 31 (guide member). Furthermore, the manual feeding device 15 (sheet conveying device) shown in Figure 16(B) has three feeding rollers 17A, 17B, and 17C (conveying means) arranged side by side at intervals on a rotating shaft, and is configured to rotate integrally by the drive of a drive mechanism (not shown). The upper guide member 31 has multiple recesses 31b1 and 31b2 formed in it, corresponding to the positions between adjacent feed rollers among the three feed rollers 17A, 17B, and 17C. Specifically, the first recess 31b1 is formed at a position corresponding to the space between the first feed roller 17A and the second feed roller 17B (the central position shown by the dashed line), and the second recess 31b2 is formed at a position corresponding to the space between the second feed roller 17B and the third feed roller 17C (the central position shown by the dashed line). This configuration also produces the same effect as that shown in Figure 16(A). The same configuration can also be used when four or more feed rollers are installed. In this specification, the term "multiple conveying means" is defined to include not only those in which multiple feed rollers are rotated independently, but also those in which multiple feed rollers are mounted on a rotating shaft and rotated integrally, as shown in Figures 16(A) and (B) (or Figure 17 described later).

[0036] <Modification 5> As shown in Figure 17, in Modification 5, the manual feeding device 15 (sheet conveying device) has multiple feeding rollers 17A and 17B (conveying means) arranged in the width direction (left-right direction in Figure 17), similar to that in Figure 16(A). As shown in Figure 17, in the modified example 5, the upper guide member 31 (guide member) has multiple recesses 31b1 and 31b2 formed therein, corresponding to the multiple feed rollers 17A and 17B (conveying means). Specifically, in Figure 17, two feed rollers 17A and 17B (conveying means) are arranged side by side with a gap between them on a rotating shaft, and are configured to rotate integrally by the drive of a drive mechanism (not shown). The upper guide member 31 is configured such that the widthwise position of the top 31e in the recess 31b substantially coincides with the central positions of the two feeding rollers 17A and 17B (the positions shown by the dashed lines in Figure 17). This configuration is useful when a conveying means uses two feed rollers 17A and 17B arranged side by side, and when the wavy portion Px of the sheet P being fed is formed at the respective positions of the two feed rollers 17A and 17B. In such cases, even if the leading edge of the sheet P conveyed by the feed rollers 17A and 17B becomes wavy, a recess 31b is formed at the position of the upper guide member 31 corresponding to that position. Therefore, the problem of the sheet P jamming at the upper guide member 31 (guide member) can be easily mitigated. The same configuration can be used when three or more feed rollers are installed.

[0037] <Variation 6> As shown in Figure 18, the sheet conveying device 150 in modified example 6 does not use a feed roller 17 or a separation pad 18 as a conveying means, as in the manual feed device 15 shown in Figure 2, but instead uses a pair of conveying rollers 35 consisting of two conveying rollers as a conveying means. As shown in Figure 18, the sheet conveying device 150 in Modification 6 is provided with a pair of conveying rollers 35 in which two conveying rollers come into contact to form a nip, and guide members 50 and 51 that guide the sheet P conveyed by the pair of conveying rollers 35 (conveying means). A sheet conveying path is formed between the upper guide member 50 and the lower guide member 51, and the sheet P is conveyed in the conveying direction (in the direction of the dashed arrow) by the pair of conveying rollers 35. The upper guide member 50 and the lower guide member 51 are provided with reference guide surfaces 50a and 51a, respectively, to which the leading edge of the sheet P delivered from the nip of the pair of conveying rollers 35 can come into contact. However, these reference guide surfaces 50a and 51a are also considered to "extend along the conveying direction." Such a sheet conveying path is provided, for example, at the position of the pair of conveying rollers 35 shown in Figure 1, but its position is not limited to this. Furthermore, the sheet conveying path is not limited to extending substantially horizontally from the nip of the pair of conveying rollers, as shown in Figure 18. Furthermore, the upper guide member 50 shown in Figure 18(A) is provided with a recess 50b that is recessed in the retraction direction away from the sheet transport path relative to the reference guide surface 50a. Similar to that in Figure 4, the recess 50b has a corner that connects to the reference guide surface 50a, extending downstream in the transport direction from the most recessed top in the retraction direction. The recess 50b is inclined downstream in the transport direction and also inclined outward in the width direction within the plane of the reference guide surface 50a, with a pair of inclined surfaces connecting to the reference guide surface 50a positioned to sandwich the corner. This configuration is useful when a wavy portion Px that protrudes upward is formed at the leading edge of the sheet P being conveyed by the conveyor roller pair 35. On the other hand, the lower guide member 51 shown in Figure 18(B) is provided with a recess 51b that is recessed in the retraction direction away from the sheet transport path relative to the reference guide surface 51a. The recess 51b, similar to that in Figure 4, has a corner formed that connects to the reference guide surface 51a, extending downstream in the transport direction from the most recessed top in the retraction direction. The recess 51b is inclined downstream in the transport direction and also inclined outward in the width direction within the plane of the reference guide surface 51a, with a pair of inclined surfaces connecting to the reference guide surface 51a arranged to sandwich the corner. This configuration is useful when a downwardly protruding wavy portion Px is formed at the leading edge of the sheet P being conveyed by the conveyor roller pair 35. Furthermore, in such cases, even if the leading edge of the sheet P conveyed by the conveyor roller pair 35 becomes wavy, a recess 50b (or recess 51b) is formed at the position of the upper guide member 50 (or lower guide member 51) corresponding to that position, thus easily mitigating the problem of the sheet P jamming at the position of the upper guide member 50 (or lower guide member 51). In modification 6, recesses 50b and 51b were formed in only one of the upper guide member 50 or the lower guide member 51. However, if the direction of the wavy portion Px formed on the sheet P is not determined, it is preferable to form recesses 50b and 51b in both the upper guide member 50 and the lower guide member 51.

[0038] As described above, the manual feeding device 15 (sheet conveying device) in this embodiment is provided with a feeding roller 17 (conveying means) for conveying the sheet P, and an upper guide member 31 (guide member) for guiding the sheet P conveyed by the feeding roller 17 to the downstream side in the conveying direction. The upper guide member 31 is provided with a reference guide surface 31a extending along the conveying direction, and a recess 31b recessed in the retraction direction away from the sheet conveying path relative to the reference guide surface 31a. The recess 31b has a corner portion 31c formed from the most recessed top portion 31e in the retraction direction, extending downstream in the conveying direction and connecting to the reference guide surface 31a. Furthermore, the recess 31b is inclined toward the downstream side in the conveying direction, and within the plane of the reference guide surface 31a, it is inclined toward the outside in the width direction perpendicular to the conveying direction, and a pair of inclined surfaces 31d connected to the reference guide surface 31a are arranged so as to sandwich the corner portion 31c. This makes it possible to easily reduce the problem of the sheet P jamming at the upper guide member 31 (guide member) even if the leading edge of the sheet P conveyed by the feed roller 17 (conveying means) becomes wavy.

[0039] In this embodiment, the present invention was applied to a manual feed device 15 installed so as to be exposed to the outside of the image forming apparatus 1. However, the present invention can also be applied to a feed device as a sheet transport device installed inside the image forming apparatus 1, to a document transport unit 10 (automatic document transport device) as a sheet transport device, and to a sheet transport device installed in the sheet transport path. Furthermore, although the present invention was applied to a manual feed device 15 (sheet transport device) installed in a monochrome image forming apparatus 1 in this embodiment, the present invention can naturally also be applied to a sheet transport device installed in a color image forming apparatus. Furthermore, although this embodiment applies the present invention to a manual feed device 15 (sheet transport device) installed in an electrophotographic image forming apparatus 1, the application of the present invention is not limited to this, and the present invention can also be applied to sheet transport devices installed in other types of image forming apparatuses (for example, inkjet image forming apparatuses or stencil printing machines). Furthermore, in this embodiment, a separation pad 18 was used as the separation member in the conveying means, but a separation roller can also be used as the separation member. Furthermore, even in such cases, the same effects as those of this embodiment can be obtained.

[0040] It is clear that the present invention is not limited to this embodiment, and that this embodiment can be modified as appropriate within the scope of the technical concept of the present invention, in addition to what is suggested here. Furthermore, the number, position, shape, etc. of the constituent members are not limited to this embodiment, and can be set to a number, position, shape, etc. that is suitable for carrying out the present invention.

[0041] In this specification, the term "sheet" is defined to include not only ordinary paper (sheets), but also all sheet-like materials such as coated paper, label paper, OHP sheets, and film, and further includes original documents fed by an automatic document transport device. [Explanation of symbols]

[0042] 1. Image forming apparatus (image forming apparatus main unit), 15. Manual feeding device (sheet conveying device), 16 manual feed trays, 17 Feeding roller (conveying means), 18 Separation pad (separation member, transport means), 19 Compression spring (biasing member, conveying means), 30 pairs of conveyor rollers, 31 Upper guide member (guide member), 31a Reference guide surface, 31b recess, 31c corner, 31d slope, 31d1 curved surface, 31e top, 31f Second reference guide surface, 31x Rib, P sheet, Px corrugated section.

[0043] Furthermore, the embodiments of the present invention can also be, for example, combinations of appendices 1 to 13 as follows. (Note 1) A conveying means for transporting sheets, A guide member that guides the sheet conveyed by the conveying means to the downstream side in the conveying direction, Equipped with, The guide member is A reference guide surface extending along the aforementioned transport direction, A recess is provided that is recessed in the retraction direction away from the sheet transport path relative to the aforementioned reference guide surface, It is equipped with, The aforementioned recess is A corner portion that connects to the reference guide surface toward the downstream side in the transport direction, extending from the most recessed top portion in the retraction direction, Arranged to sandwich the aforementioned corner, inclined toward the downstream side in the conveying direction, and inclined toward the outward side in the width direction perpendicular to the conveying direction within the plane of the reference guide surface, a pair of inclined surfaces connected to the reference guide surface, A sheet conveying device characterized by the formation of a [specific feature]. (Note 2) The sheet conveying device according to Appendix 1, characterized in that the position of the top portion in the width direction substantially coincides with the central position in the width direction of the wavy portion generated in the sheet conveyed by the conveying means. (Note 3) The sheet conveying device according to Appendix 1 or Appendix 2, characterized in that the position of the top of the recess in the width direction substantially coincides with the central position of the conveying means in the width direction. (Note 4) Multiple conveying means are provided in the width direction, The sheet conveying device according to Appendix 3, characterized in that the guide member has a plurality of recesses formed in it corresponding to the plurality of conveying means. (Note 5) Multiple conveying means are provided in the width direction, The sheet conveying device according to Appendix 1 or Appendix 2, characterized in that the guide member has recesses formed corresponding to the positions between adjacent conveying means in the plurality of conveying means. (Note 6) The sheet conveying device according to any one of the appendices 1 to 5, characterized in that the guide member has a curved shape at the portion where the reference guide surface and the inclined surface are connected. (Note 7) The sheet conveying device according to any one of the appendices 1 to 6, characterized in that the guide member has a corner that is formed in an angular shape. (Note 8) The sheet conveying device according to any one of the appendices 1 to 6, characterized in that the guide member has a curved corner. (Note 9) The sheet conveying device according to any one of the appendices 1 to 8, characterized in that the guide member is formed such that the pair of inclined surfaces are symmetrical with respect to the corner. (Note 10) The sheet conveying device according to any one of the appendices 1 to 9, characterized in that the guide member has a pair of second reference guide surfaces formed in a direction closer to the sheet conveying path than the reference guide surface, and these surfaces are formed to sandwich the reference guide surface. (Note 11) The aforementioned conveying means is A feeding roller and a separating member that contacts the feeding roller, or A sheet conveying device according to any one of the appendices 1 to 10, characterized by being a conveying roller pair consisting of two conveying rollers. (Note 12) A conveying means for transporting sheets, A guide member that guides the sheet conveyed by the conveying means to the downstream side in the conveying direction, Equipped with, The guide member is A reference guide surface extending along the aforementioned transport direction, A recess is provided that is recessed in the retraction direction away from the sheet transport path relative to the aforementioned reference guide surface, It is equipped with, The sheet conveying device is characterized in that the recess is inclined toward the downstream side in the conveying direction, with the most recessed apex in the retraction direction in between, and is inclined toward the outward side in the width direction perpendicular to the conveying direction within the plane of the reference guide surface, thereby forming a pair of inclined surfaces connected to the reference guide surface. (Note 13) An image forming apparatus characterized by being equipped with a sheet transport device as described in any of Appendix 1 to Appendix 12. [Prior art documents] [Patent Documents]

[0044] [Patent Document 1] Patent No. 3062508

Claims

1. A conveying means for transporting sheets, A guide member that guides the sheet conveyed by the conveying means to the downstream side in the conveying direction, Equipped with, The guide member is A reference guide surface extending along the aforementioned transport direction, A recess is provided that is recessed in the retraction direction away from the sheet transport path relative to the aforementioned reference guide surface, It is equipped with, The aforementioned recess is A corner portion that connects to the reference guide surface toward the downstream side in the transport direction, extending from the most recessed top portion in the retraction direction, Arranged to sandwich the aforementioned corner, inclined toward the downstream side in the conveying direction, and inclined toward the outward side in the width direction perpendicular to the conveying direction within the plane of the reference guide surface, a pair of inclined surfaces connected to the reference guide surface, A sheet conveying device characterized by the formation of a [specific feature].

2. The sheet conveying device according to claim 1, characterized in that the position of the top portion in the width direction substantially coincides with the central position in the width direction of the wavy portion generated in the sheet conveyed by the conveying means.

3. The sheet conveying device according to claim 1 or 2, characterized in that the position of the top of the recess in the width direction substantially coincides with the central position of the conveying means in the width direction.

4. Multiple conveying means are provided in the width direction, The sheet conveying device according to claim 3, characterized in that the guide member has a plurality of recesses formed in it corresponding to the plurality of conveying means.

5. Multiple conveying means are provided in the width direction, The sheet conveying device according to claim 1 or 2, characterized in that the guide member has recesses formed corresponding to the positions between adjacent conveying means in the plurality of conveying means.

6. The sheet conveying device according to claim 1 or 2, characterized in that the portion of the guide member where the reference guide surface and the inclined surface are connected is formed in a curved shape.

7. The sheet conveying device according to claim 1 or 2, characterized in that the guide member has a corner that is formed in an angular shape.

8. The sheet conveying device according to claim 1 or 2, characterized in that the corner portion of the guide member is formed in a curved shape.

9. The sheet conveying device according to claim 1 or 2, characterized in that the guide member is formed such that the pair of inclined surfaces are symmetrical with respect to the corner.

10. The sheet conveying device according to claim 1 or 2, characterized in that the guide member has a pair of second reference guide surfaces formed in a direction closer to the sheet conveying path than the reference guide surface, and these second reference guide surfaces are formed to sandwich the reference guide surface.

11. The aforementioned conveying means is A feeding roller and a separating member that contacts the feeding roller, or The sheet conveying device according to claim 1 or 2, characterized in that it is a pair of conveying rollers consisting of two conveying rollers.

12. A conveying means for transporting sheets, A guide member that guides the sheet conveyed by the conveying means to the downstream side in the conveying direction, Equipped with, The guide member is A reference guide surface extending along the aforementioned transport direction, A recess is provided that is recessed in the retraction direction away from the sheet transport path relative to the aforementioned reference guide surface, It is equipped with, The sheet conveying device is characterized in that the recess is inclined toward the downstream side in the conveying direction, with the most recessed apex in the retraction direction in between, and is inclined toward the outward side in the width direction perpendicular to the conveying direction within the plane of the reference guide surface, thereby forming a pair of inclined surfaces connected to the reference guide surface.

13. An image forming apparatus characterized by comprising a sheet transport device according to claim 1 or claim 12.

Images