Sheet feeding device and image forming apparatus

Abstract

To prevent non-feeding at the time of re-feeding by a feeding roller when non-feeding of a sheet occurs.SOLUTION: The sheet feeding device according to the present invention is provided with: a pickup roller 54 (feed roller) that feeds the sheet P placed on the bottom plate 42 (loading portion) in the feeding direction; a non-feeding detection sensor 70 (detection means) that can detect non-feeding of the sheet P by the pickup roller 54; and a motor 90 (adjustment means) that can adjust the orientation of the pickup roller 54 in the rotational direction. Furthermore, when the non-feeding of the sheet P by the pickup roller 54 is detected by the non-feeding detection sensor 70, and the refeeding of the sheet P by the pickup roller 54 is repeatedly performed, the rotation direction of the pickup roller 54 is configured to execute a retry mode that controls the motor 90 so that the position at the start of the subsequent refeeding is displaced from that at the start of the previous refeeding.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device that feeds sheets such as paper, and to an image forming apparatus including the same, such as a copying machine, a printer, a facsimile machine, or a combination machine thereof, or a printing machine. [Background technology]

[0002] Conventionally, in sheet feeding devices installed in image forming devices such as copiers, printers, and printing machines, a technology has been widely known in which, when a sheet is not fed, a feeding roller performs re-feeding (retry feeding) (see, for example, Patent Document 1).

[0003] On the other hand, Patent Document 1 discloses a technique for feeding sheets by repeatedly rotating and stopping the rotation of a feeding roller in order to reduce non-feeding of sheets. Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional sheet feeding device, once a sheet has not been fed, the sheet is likely to not be fed again even if the feeding roller attempts to feed the sheet again.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a sheet feeding device and an image forming apparatus that, when a sheet is not fed, is less likely to fail to feed when the feeding roller re-feeds the sheet. [Means for solving the problem]

[0006] The sheet feeding device of this invention comprises a feed roller that feeds a sheet placed on a loading section in a feeding direction, a detection means that can detect non-feeding of a sheet by the feed roller, and an adjustment means that can adjust the orientation of the feed roller in the rotational direction, and is configured to be able to execute a retry mode that controls the adjustment means so that when non-feeding of a sheet by the feed roller is detected by the detection means and the feed roller repeatedly re-feeds a single sheet, the orientation of the feed roller in the rotational direction at the start of a subsequent re-feed is displaced from that at the start of a previous re-feed. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a sheet feeding device and an image forming apparatus in which, when a sheet has not been fed, the sheet is less likely to not be fed again by the feeding roller. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of a sheet feeding device. [Figure 3] 10 is a timing chart showing the relationship between the rotation speed of the pickup roller and the signal of the non-feed detection sensor when feeding is performed normally by the pickup roller. [Figure 4] 10 is a timing chart showing the relationship between the rotation speed of the pickup roller and the signal of the non-feed detection sensor when a non-feed by the pickup roller occurs and the first re-feed is performed normally. [Figure 5] This is a timing chart showing the relationship between the rotation speed of the pickup roller and the signal of the non-feed detection sensor when there is a non-feed by the pickup roller, there is also a non-feed during the first re-feed, and the second re-feed is performed normally. [Figure 6](A) A diagram showing the orientation of the pickup roller in the direction of rotation at the start of the first feeding, (B) A diagram showing the orientation of the pickup roller in the direction of rotation at the start of the first re-feeding, and (C) A diagram showing the orientation of the pickup roller in the direction of rotation at the start of the second re-feeding. [Figure 7] 10 is a flowchart showing control when non-feeding by the pickup roller is detected. [Figure 8] As a comparative example, this is a timing chart showing the relationship between the rotation speed of the pickup roller and the signal of the non-feed detection sensor when there is a non-feed by the pickup roller, there is also a non-feed during the first re-feed, and the second re-feed is performed normally. [Figure 9] 10A and 10B are diagrams showing the orientation positions of the pickup roller and the feed roller in the rotation direction at the start of feeding and at the start of re-feeding, according to Modification 1. FIG. [Figure 10] 10 is a flowchart showing control when non-feeding by the pickup roller is detected according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0010] First, the overall configuration and operation of an image forming apparatus 1 will be described with reference to FIG. In Figure 1, 1 indicates a copier as an image forming device, 2 indicates a document reading unit that optically reads image information from a document D, 3 indicates an exposure unit that irradiates a photosensitive drum 5 with exposure light L based on the image information read by the document reading unit 2, 4 indicates an image creating unit that forms a toner image (image) on the photosensitive drum 5, and 7 indicates a transfer unit (image forming unit) that transfers the toner image formed on the photosensitive drum 5 to a sheet P. Also, 10 indicates a document transport section (automatic document transport device) that transports the set document D to the document reading section 2, 12 and 13 indicate sheet feeding devices that feed sheets P stored in the feeding cassette 40, and 16 indicates a manual sheet feeding device (manual sheet feeding device) that feeds sheets P that the user has manually set. Also, 17 denotes a pair of registration rollers (pair of conveying rollers) that convey the sheet P toward the transfer section 7, 20 denotes a fixing device that fixes the toner image (unfixed image) carried on the sheet P, 21 denotes a fixing roller installed in the fixing device 20, 22 denotes a pressure roller installed in the fixing device 20, and 31 denotes a paper output tray on which the sheet P discharged from the device main body 1 is stacked. Further, 40 and 40' denote feeding cassettes installed in the sheet feeding devices 12 and 13, respectively, and 52 denotes a feeding mechanism installed in the sheet feeding devices 12, 13, and 16, respectively. An operation display panel 80 (operation display unit) is provided on the exterior of the image forming apparatus 1 for displaying various information about the image forming apparatus 1 and inputting various commands.

[0011] With reference to FIG. 1, the operation of the image forming apparatus main body 1 during normal image formation (printing) will be described. First, the document D is transported (fed) from the document table in the direction of the arrow in the figure by the transport rollers of the document transport unit 10, and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above it. The optical image information read by the document reading unit 2 is converted into an electrical signal and then transmitted to the exposure unit 3 (writing unit). The exposure unit 3 then emits exposure light L, such as a laser beam, based on the image information in the electrical signal onto the photosensitive drum 5 of the imaging unit 4.

[0012] Meanwhile, in the image creating unit 4, the photosensitive drum 5 rotates clockwise in Figure 1, and after going through a predetermined image creating process (charging process, exposure process, development process), 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 a sheet P conveyed by a pair of registration rollers 17 in 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, one of the plurality of sheet feeding devices 12, 13 of the image forming apparatus main body 1 is automatically or manually selected (for example, it is assumed that the lower sheet feeding device 13 is selected). Then, the uppermost sheet P of paper or other sheets stored in the feeding cassette 40 of the sheet feeding device 13 is fed by the feeding mechanism 52 and conveyed toward the conveying path K. Thereafter, the sheet P passes through the conveying path K on which a plurality of conveying rollers are arranged, and reaches the position of the registration roller pair 17. When the sheet feeding device 16 (manual sheet feeding device) installed on the side of the device main body 1 is selected, the sheet P placed by the user on the manual feed tray of the sheet feeding device 16 (the uppermost sheet P when multiple sheets P are stacked) is fed by the feeding mechanism 52 toward the conveying path and reaches the position of the registration roller pair 17.

[0014] Then, the pair of registration rollers 17 starts to rotate, and the sheet P, after having had its skew corrected by the pair of registration rollers 17, is transported toward the transfer section 7 (image forming section) in time to align it with the image formed on the photosensitive drum 5.

[0015] After the transfer process, the sheet P passes through the transfer unit 7, then travels through a conveying path and reaches the fixing device 20. The sheet P that has reached the fixing device 20 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 members 21 and 22 (the fixing process). The sheet P after the fixing process with the toner image fixed is sent out from between the fixing roller 21 and the pressure roller 22 (the fixing nip), and then discharged from the image forming apparatus main body 1 and stacked on the paper output tray 31 as an output image. In this way, a series of image forming processes (printing) is completed.

[0016] Next, the sheet feeding device according to the present embodiment will be described with reference to FIG. Of the multiple sheet feeding devices 12, 13 installed inside the device main body 1, the following will explain the lower sheet feeding device 13. However, the upper sheet feeding device 12 has almost the same configuration as the lower sheet feeding device 13 except for its installation position, so its explanation will be omitted.

[0017] Referring to Figure 2, the sheet feeding device 13 is mainly composed of a feeding cassette 40 configured to be able to load multiple sheets (or one sheet) P, and a sheet feeding device main body (in this embodiment, formed integrally with the image forming device main body 1) in which a feeding mechanism 52 for feeding the sheets P loaded in the feeding cassette 40 is installed. The feeding cassette 40 is composed of a bottom plate 42 as a loading section that can be raised and lowered, a side fence (not shown) that can move in the width direction, an end fence (not shown) that can move in the feeding direction, and a non-feeding detection sensor 70 as a detection means.

[0018] As shown in FIG. 2, the feeding mechanism 52 is made up of a feed roller 53, a pickup roller 54 as a feeding roller, a separation roller 55, and the like. The feed roller 53 is installed at the leading end of the feeding direction (the direction of the white arrow in Figure 2, which is the conveying direction) of the sheet P stacked on the bottom plate 42 (loading portion) of the feed cassette 40, and contacts the top surface of the sheet P and rotates along the feeding direction of the sheet P (counterclockwise rotation in Figure 2) to feed the sheet P in the feeding direction indicated by the dotted arrow. In this embodiment, the outer diameter of the feed roller 53 and the outer diameter of the pickup roller 54 are set to be equal to each other.

[0019] The pickup roller 54, which serves as a feeding roller, rotates counterclockwise in FIG. 2 along the running direction while in contact with the surface (top surface) of the sheet P loaded in the feeding cassette 40, thereby transporting the sheet P toward the position of the feed roller 53. A timing belt 59 is stretched and supported between a pulley mounted on pickup roller 54 and a pulley mounted on feed roller 53. Driving force is transmitted from motor 90 (feed motor) to pickup roller 54 via a gear train, feed roller 53, and timing belt 59, causing pickup roller 54 to rotate counterclockwise in FIG.

[0020] The pickup roller 54 is configured to be able to come into contact with and separate from the sheets P (the uppermost sheet P) stacked in the feed cassette 40. That is, the pickup roller 54 is configured to be able to move between a retracted position where it does not come into contact with the sheets P stacked in the feed cassette 40 and a contact position where it comes into contact with the sheets P. More specifically, the pickup roller 54 is rotatably held by an arm 58. The arm 58 is rotatably held by the shaft portion of the feed roller 53. A spring that biases the pickup roller 54 to move to the retracted position and a solenoid that moves the pickup roller 54 to the abutment position against the biasing force of the spring are connected to the arm 58. When the solenoid is turned on (or off) under the control of the control unit, the pickup roller 54 moves to the abutment position as shown in FIG. 2, and when the solenoid is turned off (or on), the pickup roller 54 moves to the retracted position. The timing belt 59 is stretched and supported by the pulley of the pickup roller 54 and the pulley of the feed roller 53 even when the pickup roller 54 is moving toward or away from the feed roller 53 .

[0021] A separation roller 55 as a separation member is disposed so as to form a nip between itself and the feed roller 53 . When one sheet P is sandwiched in the nip portion and when no sheet P is sandwiched in the nip portion, the separation roller 55 rotates in the forward direction (the direction of the dashed arrow in Figure 2, which is clockwise) along the feeding direction. On the other hand, when multiple sheets are sandwiched in the nip portion, separation roller 55 rotates in the direction opposite to the forward direction described above (the direction of the solid arrow in FIG. 2, which is the counterclockwise direction.) As a result, the uppermost sheet P of the multiple sheets P sandwiched in the nip portion is fed in the feeding direction in accordance with the rotation of feed roller 53, and the lower sheets P are transported in the direction opposite to the feeding direction (forward direction), thereby preventing double feeding of sheets P. In this embodiment, the roller pair consisting of the feed roller 53 and the separation roller 55 is configured so that when multiple sheets P are fed, a load such as a torque limiter is applied, causing the separation roller 55 to rotate in the reverse direction and separate only one sheet P and feed it in the feeding direction. On the other hand, it is also possible to configure the roller pair so that when multiple sheets P are fed, a load such as a torque limiter is applied, causing the separation roller 55 to not rotate (or to rotate slightly in the forward direction), and separate only one sheet P and feed it in the feeding direction. The non-feed detection sensor 70 functions as a detection means capable of detecting non-feeding of the sheet P by the pickup roller 54 (or the feed roller 53) as a feed roller, which will be described in detail later.

[0022] In the sheet feeding device 13 of the present embodiment, the bottom plate 42 (loading portion) is raised and lowered in the vertical direction depending on the number of sheets P loaded on the bottom plate 42 so that the pickup roller 54 can contact the uppermost sheet P loaded in the feed cassette 40. Then, the sheet P is fed after the pickup roller 54 has descended to a position where it contacts the upper surface of the sheet P loaded on the bottom plate 42 whose vertical position has been adjusted. An entrance guide plate is provided between the feeding cassette 40 and the nip between the feed roller 53 and the separation roller 55.

[0023] In the sheet feeding device 13 configured as above, when no sheet P is set in the feeding cassette 40, this state is detected by an end detection sensor installed at the bottom. At this time, the bottom plate 42 is in a state where it is lowered to the lowest set position far away from the pickup roller 54 (a position where a sheet P can be set). When a sheet P is set in the feeding cassette 40, the state is detected by an end detection sensor, and the control unit 100 controls the motor to raise the bottom plate 42 to a position where the uppermost sheet P of the set sheet P contacts the pickup roller 54 (the position shown in Figure 2). 2, with pickup roller 54 in contact with the upper surface of the uppermost sheet P placed on bottom plate 42, control unit 100 controls motor 90 to start rotating pickup roller 54 counterclockwise, and at the same time, feed roller 53 and separation roller 55 start rotating. As a result, pickup roller 54 transports the uppermost sheet P of the sheet stack placed in feed cassette 40 toward the nip between feed roller 53 and separation roller 55, and one sheet P is separated from the nip and transported toward the image forming unit. Furthermore, when all the sheets P placed on the feeding cassette 40 have been fed and no sheets P are set in the feeding cassette 40, this state is detected by the end detection sensor, and the control unit controls the motor to lower the bottom plate 42 to the set position again.

[0024] Hereinafter, the characteristic configuration and operation of the sheet feeding device 13 (image forming apparatus 1) in this embodiment will be described with reference to FIGS. As previously explained using Figure 2 etc., the sheet feeding device 13 in this embodiment is provided with a pickup roller 54 as a feeding roller that feeds the sheet P placed on the bottom plate 42 as a loading section in the feeding direction, and a non-feeding detection sensor 70 as a detection means that can detect non-feeding of the sheet P by the pickup roller 54 (feeding roller).

[0025] The non-feed detection sensor 70 as the detection means is installed downstream in the feeding direction relative to the pickup roller 54 (feed roller), and is a photosensor that can optically detect the presence or absence of the sheet P at that position. Specifically, the non-feed detection sensor 70 in this embodiment is disposed in a position near the downstream side of the feeding mechanism 52 so as to be able to face the upper surface of the sheet P. Then, when it is determined that the sheet P has been transported beyond the transport distance W (an integral value when the horizontal axis is time and the vertical axis is the number of rotations of the pickup roller 54) of the sheet P that would be assumed if there had been no non-feeding after the pickup roller 54 (feed roller) started to feed, it is determined that the sheet P has not been fed (a state in which the sheet P has not been fed normally and has jammed (conveyance has stopped)). Such a determination is made by the control unit 100 based on the integral value calculated from the driving time and number of rotations of the pickup roller 54.

[0026] In this embodiment, in the feeding operation for one sheet P, the pickup roller 54 does not rotate intermittently and does not stop rotating, so when the non-feed detection sensor 70 cannot detect the sheet P even after a predetermined time T0 has elapsed since the pickup roller 54 started feeding, it determines that the sheet P has not been fed. 3, when the motor 90 (see FIG. 2) starts to rotate the pickup roller 54 and the sheet P is fed normally, the sheet P will reach the position of the non-feed detection sensor 70 after approximately time T', and the signal of the non-feed detection sensor 70 will change from OFF to ON. Then, the feeding operation for the sheet P will continue as is (the motor 90 will continue to be driven). On the other hand, when the signal of the non-feed detection sensor 70 does not change from OFF to ON even after a predetermined time T0 (>T') has elapsed since the motor 90 started rotating the pickup roller 54, it is determined that the sheet P has not been fed. Specifically, when the control unit 100 (comprised of a CPU 101, a ROM 102, a RAM 103, etc.) does not recognize a change in the signal of the non-feed detection sensor 70, it is determined that the non-feed of the sheet P has occurred. Then, under the control of the control unit 100, the driving of the motor 90 (feed mechanism 52) is stopped. At this time, the motor 90 is controlled so that the attitude (rotation angle) of the pickup roller 54 in the rotation direction is different from that at the start of rotation, and thereafter, the sheet P is re-fed (retried), which will be described in detail later with reference to Figures 4 to 7, etc. In this embodiment, the pickup roller 54 is controlled to stop rotating after it is detected that the sheet P has not yet reached the sensor position, but it is also possible to control the pickup roller 54 to stop rotating before the sheet P is expected to reach the sensor position.

[0027] Here, in this embodiment, a reflective photosensor is used as the non-feed detection sensor 70, which detects the presence or absence of sheet P based on whether light emitted from a light-emitting element is reflected on sheet P and received by a light-receiving element. Alternatively, the non-feed detection sensor 70 may be a transmission type photosensor that detects the presence or absence of the sheet P based on whether the light emitted from the light-emitting element is not blocked by the sheet P and is received by the light-receiving element. Furthermore, as the non-feed detection sensor 70, a photosensor that optically detects the operation of a filler that oscillates in conjunction with the passage (presence or absence) of the sheet P can also be used.

[0028] Here, in the sheet feeding device 13 of this embodiment, the motor 90 (and the control unit 100) that rotates the pickup roller 54 is configured to function as an adjustment means that can adjust the attitude (rotation angle) of the pickup roller 54 in the rotational direction.

[0029] The device is configured to be able to execute a "retry mode" in which, when the non-feeding detection sensor 70 (detection means) detects that the pickup roller 54 (feed roller) has not fed the sheet P and the pickup roller 54 starts to feed the sheet P again (retry), the motor 90 (adjustment means) is controlled so that the orientation of the pickup roller 54 in the rotational direction is displaced from that at the start of the initial feeding. 4 and 5, the above-mentioned "retry mode" can be executed each time the pickup roller 54 (feed roller) repeatedly re-feeds one sheet P. That is, each time a predetermined condition is satisfied and re-feeding is repeatedly performed, the attitude (rotation angle) of the pickup roller 54 at the start of re-feeding is changed.

[0030] Furthermore, in the sheet feeding device 13 of this embodiment, when the non-feeding detection sensor 70 (detection means) detects that the pickup roller 54 (feed roller) has not fed the sheet P, and the pickup roller 54 repeatedly tries to feed one sheet P again (retries), a "retry mode" is executable in which the motor 90 (adjustment means) is controlled so that the orientation of the pickup roller 54 in the rotation direction is displaced from that at the start of the previous re-feeding to that at the start of the subsequent re-feeding. In this way, the "retry mode" is a control mode that controls the motor 90 (adjustment means) so that when the feeding operation is repeated to normally feed a single sheet P that has failed to be fed, the orientation of the pickup roller 54 in the rotational direction at the start of the next feeding operation is displaced from the orientation of the pickup roller 54 (feed roller) in the rotational direction at the start of the previous feeding operation.

[0031] In this embodiment, when the non-feeding detection sensor 70 (detection means) detects the non-feeding of the sheet P by the pickup roller 54 (feed roller) during the first feeding and the rotation of the pickup roller 54 is stopped, the motor 90 (adjustment means) is controlled so that the attitude (rotation angle) of the pickup roller 54 in the rotation direction is displaced from that at the start of rotation. Even when such control is performed, when the first retry of feeding (re-feeding) of the sheet P by the pickup roller 54 is started, the rotational orientation (rotation angle) of the pickup roller 54 is displaced from that at the start of the first feeding (when rotation stopped during the first feeding), so the above-mentioned "retry mode" is being executed.

[0032] More specifically, referring to FIG. 6, although the pickup roller 54 does not appear to be divided, its rotational orientation (rotation angle) is set so that its surface is roughly divided into four sections (A to D). That is, by controlling the motor 90 by the control unit 100, feeding can be started with the surface of area A in contact with the sheet P as shown in Figure 6(A), feeding can be started with the surface of area B in contact with the sheet P as shown in Figure 6(B), feeding can be started with the surface of area C in contact with the sheet P as shown in Figure 6(C), or feeding can be started with the surface of area D in contact with the sheet P, although not shown. When the sheet P is fed for the first time, the surface of area A is brought into contact with the sheet P as shown in FIG. 6(A), when the first re-feeding (retry) is performed, the surface of area B is brought into contact with the sheet P as shown in FIG. 6(B), and when the second re-feeding (retry) is performed, the surface of area C is brought into contact with the sheet P as shown in FIG. 6(C). In addition, the adjustment control of the rotational orientation of the pickup roller 54 can be achieved by installing an encoder on the shaft of the pickup roller 54 to detect and control the rotation speed of the pickup roller 54, or by controlling the rotation speed (angle) of the motor 90. Furthermore, the motor 90 may be a stepping motor or a position-controllable inner brushless motor. In the present embodiment, the rotation direction that displaces the contact portions A to D of the pickup roller 54 is set to a direction that allows the sheet P to be conveyed (counterclockwise in FIGS. 2 and 6).

[0033] In this manner, in this embodiment, when non-feeding of the sheet P occurs, the retry mode is performed so that the portion of the pickup roller 54 that comes into contact with the sheet P changes each time re-feeding is repeated. This reduces the occurrence of problems such as failure to feed again when retrying feeding. In particular, in this embodiment, even when re-feeding is repeated, including at the start of the initial feeding, the part of the pickup roller 54 that comes into contact with the sheet P is controlled to be different each time, thereby further enhancing the effect of reducing the occurrence of problems such as non-feeding occurring again.

[0034] Specifically, the moment the pickup roller 54 starts rotating, static friction acts between the pickup roller 54 and the sheet P, providing a strong conveying force. However, this friction changes depending on the state of the contact area between the pickup roller 54 and the sheet P. Specifically, the friction tends to decrease due to wear on the surface of the pickup roller 54 and the adhesion of foreign matter such as paper dust and toner. When the friction decreases, the force exerted by the pickup roller 54 on the sheet P is outweighed by the adhesion between the sheets P and the load from the side fences, causing the pickup roller 54 to slip and fail to convey the sheet P (leading to a non-feed). Furthermore, if the pickup roller 54 slips at the start of feeding (when rotation begins), a kinetic friction force smaller than the static friction acts between the pickup roller 54 and the sheet P, causing the slip (non-feed) to continue. In other words, because the friction changes depending on the state of the contact area between the pickup roller 54 and the sheet P, attempting to re-feed the sheet at the contact surface of the pickup roller 54 that has slipped increases the likelihood of the sheet slipping again. In contrast to this, in this embodiment, the contact surface of the pickup roller 54 that comes into contact with the sheet P during re-feeding (retry) changes, so it is possible to reduce the recurrence of slippage (non-feeding) as described above. That is, in this embodiment, the areas A to D that use the static friction of the pickup roller 54 are changed every time feeding is performed, so the success rate of re-feeding improves. If re-feeding is performed many times, the sheet P may jam due to a cause other than slippage (for example, getting caught), causing the sheet P to fold like an accordion, and there is a possibility that the damage to the sheet P may become significant. For this reason, the present invention becomes even more useful. Furthermore, in this embodiment, when a non-feed occurs and the pickup roller 54 stops rotating, the pickup roller 54 is controlled to stop rotating in the desired orientation in the rotation direction. This reduces the time required for re-feeding compared to when the orientation in the rotation direction of the pickup roller 54 is changed after the pickup roller 54 has stopped rotating, thereby improving overall productivity.

[0035] In the example of FIG. 6, the rotational orientation of the pickup roller 54 is configured to be displaceable among roughly four patterns A to D (divided by a rotation angle of 90°). However, the number of displacements of the rotational orientation of the pickup roller 54 is not limited to this, and it can be configured to be displaceable in two patterns (divided by a rotation angle of 180°), or it can be configured to be displaceable in three patterns or five or more patterns. However, like the feed roller 53 and separation roller 55, the surface of the pickup roller 54 is made of an elastic material such as rubber, and is deformed by contact with the sheet P. Therefore, if the number of displacements of the orientation in the rotation direction is set too large (the rotation angle is set too small), it becomes difficult to achieve the effect of displacing the contact surface with the sheet P. Therefore, in the retry mode, it is preferable to displace the contact portion to an extent that sufficiently exceeds the nip between the pickup roller 54 and the sheet P. However, by setting the rotation angle when changing the orientation of the pickup roller 54 in the rotation direction to a relatively small value (approximately 60°), the rotation of the pickup roller 54 is reduced to the minimum necessary, thereby shortening the time required for retry mode and preventing a decrease in operability. Furthermore, in this embodiment, the rotation angle (90° in the example of FIG. 6) when changing the orientation of the rotation direction of the pickup roller 54 does not have to be uniform; for example, it can be 90° for the first re-feed and 180° for the second re-feed.

[0036] In this embodiment, when the non-feeding detection sensor 70 detects that the pickup roller 54 has not fed the sheet P during the first feeding and the pickup roller 54 is stopped from rotating, feedback control is performed so that the attitude (rotation angle) of the pickup roller 54 in the rotation direction is displaced from that at the start of rotation. On the other hand, if the non-feed detection sensor 70 detects that the pickup roller 54 has not fed the sheet P during the initial feeding, the pickup roller 54 can be stopped from rotating when it is determined that the conveyance distance W of the sheet P, which would be assumed if there had been no non-feed, has reached a predetermined distance. In such a case, the "retry mode" executed during the first subsequent re-feed is open-loop control in which the pickup roller 54 is rotated at a predetermined rotation angle before the start of the re-feed. In such a case, the retry mode may be executed when the pickup roller 54 stops rotating during the initial feeding, or may be executed between the time the pickup roller 54 stops rotating and the time the pickup roller 54 starts re-feeding. However, as explained above, the "retry mode" sets the attitude (rotation angle) of the pickup roller 54 (feed roller) and does not involve the feeding operation of the sheet P. Even in such a case, when non-feeding of the sheet P occurs, the retry mode is performed differently for the part of the pickup roller 54 that contacts the sheet P each time re-feeding is repeated, so that it is possible to reduce the occurrence of a problem in which non-feeding occurs again.

[0037] Here, in this embodiment, when re-feeding (retries) of the sheet P are repeated two or more times, the orientation of the rotation direction of the pickup roller 54 at the start of the first feeding and the orientation of the rotation direction of the pickup roller 54 after the retry mode for at least the second re-feeding are all set to be different. That is, referring to Figure 6 etc., multiple contact areas A to D are defined so that the contact area between the pickup roller 54 and the sheet P at the start of the first feeding and the contact area between the pickup roller 54 and the sheet P at the start of at least the second re-feeding are all in different positions. The reason for this setting is that even if a failure occurs during the first feeding, there is an extremely high possibility that normal feeding will be achieved if the series of operations of retrying feeding in retry mode is performed twice.

[0038] 5, in this embodiment, the conveyance distance W1 of the sheet P assumed when it is assumed that there is no non-feeding (slip) during re-feeding is set to be shorter than the conveyance distance W0 of the sheet P assumed when it is assumed that there is no non-feeding (slip) during the initial feeding (W0>W1). Note that the above-mentioned "conveyance distance W" is an integral value when the horizontal axis represents time and the vertical axis represents the number of rotations of the pickup roller 54. The reason for this control is to reduce the time required for control related to re-feeding (retry) and to prevent a decrease in productivity and a delay in notifying a jam. Furthermore, if re-feeding is performed many times over a long period of time, the sheet P may jam due to reasons other than slippage (for example, getting caught), and may fold like an accordion, making it difficult to remove the jammed sheet P. That is, as shown as a comparative example in Figure 8, if the transport distance W' from the start of re-feeding to the time when the non-feed detection sensor 70 determines that the paper is not being fed is set too long during re-feeding, this will result in reduced productivity, delayed jam notification, and reduced jam handling ability. In particular, if the phase (attitude in the direction of rotation) of the pickup roller 54 is checked after the rotation of the pickup roller 54 has stopped, and the phase (attitude in the direction of rotation) of the pickup roller 54 is changed based on the results of that check, this will result in further reductions in productivity, delays in jam notification, and reduced jam handling capabilities. In contrast, in this embodiment, the time required for control related to re-feeding (retry) is shortened, thereby preventing a decrease in productivity, a delay in jam notification, and a decrease in jam handleability.

[0039] 7 (especially step S5), in this embodiment, when the non-feed detection sensor 70 detects non-feeding of the sheet by the pickup roller 54 (feed roller) during re-feeding, if it is determined that the conveyance distance W of the sheet P due to re-feeding exceeds the predetermined value A (W>A), control is performed so that no further re-feeding is performed and a message indicating that a jam has occurred is displayed on the operation display panel 80 (see FIG. 1). This is because, even if re-feeding is performed, if it is determined that the conveyance distance W of the sheet P exceeds the predetermined value A and further that a non-feed has occurred, it is considered that a jam has occurred in the sheet P. Note that the "conveyance distance W" in this control is the distance over which the sheet P is expected to be conveyed in the feeding direction by the pickup roller 54 without slipping by performing the retry mode, and is an integral value calculated by the control unit 100 as described above. On the other hand, when non-feeding of the sheet is detected, if it is determined that the conveying distance W of the sheet P due to re-feeding does not exceed a predetermined value A (W≦A), it is determined that no jam has occurred and the sheet is controlled to be re-fed again.

[0040] Hereinafter, an example of control when non-feeding by the pickup roller 54 is detected in this embodiment will be described with reference to FIG. First, when printing starts, the pickup roller 54 of the sheet feeding device 13 starts feeding the sheet P (step S1). Then, depending on whether or not the non-feed detection sensor 70 detects a sheet, it is determined whether or not non-feeding of the fed sheet P has occurred (step S2). As a result, if it is determined that no non-feeding has occurred, printing continues as is (step S3). If the sheets P are continuously fed (during continuous paper feed), the flow from step S1 onwards is repeated, and if there is no further printing to be done, printing ends. On the other hand, if it is determined in step S2 that a non-feed has occurred, the rotation of the pickup roller 54 is temporarily stopped, and at this time the retry mode described above with reference to Fig. 6 etc. is executed (step S4). Then, in the first retry mode, step S5 is skipped and the non-feeded sheet P is re-fed (step S6). At this time, the conveying distance W in the re-feed is recorded in the RAM 103 of the control unit 100. Then, the flow from step S2 onwards is repeated, but if it is determined in step S2 that a non-feed has occurred, it is determined in step S6 whether the conveying distance W recorded in RAM 103 exceeds a predetermined value A (step S5). As a result, if it is determined that the conveying distance W does not exceed the predetermined value A, it is determined that a jam has not occurred, and the flow from step S6 onwards is performed (a second re-feed is performed). On the other hand, if it is determined in step S5 that the conveying distance W exceeds the predetermined value A, it is determined that a jam has occurred, and no further re-feeding is performed, but a message that a jam has occurred is displayed on the operation display panel 80, and operation of the image forming apparatus 1 is stopped.

[0041] As described above with reference to FIG. 2, the feeding mechanism 52 in this embodiment is configured so that the pickup roller 54 and the feed roller 53 are both rotated by a single motor 90. Therefore, when the retry mode as described above with reference to FIG. 6 and the like is executed, the orientation (rotation angle) of the feed roller 53 as well as the pickup roller 54 changes in the rotation direction. Therefore, in addition to the pickup roller 54, the feed roller 53 also functions as a feeding roller whose orientation in the rotation direction is changed from that at the start of rotation in the retry mode. A roller pair consisting of a feed roller 53 and a separation roller 55 is configured so that when sheets P are fed in multiple layers, a load such as a torque limiter is applied, and only one sheet P is separated and fed in the feeding direction. The feed roller 53 and the separation roller 55 rotate together when there is no double feeding under normal conditions, but when the friction coefficient between the rollers is reduced due to adhesion of paper dust or the like, the separation roller 55 stops rotating together, the sheet P cannot enter the nip, and a jam is likely to occur. In contrast to this, in the present embodiment, when non-feeding of sheet P is detected, a retry mode is executed so that the rotational orientation (rotation angle) when re-feeding by feed roller 53 (and separation roller 55) is different from that at the start of initial feeding, which makes it less likely that jams will occur as described above and increases the success rate when re-feeding by feed roller 53 (and separation roller 55). Furthermore, in this embodiment, since non-feed detection sensor 70 is installed downstream of feed roller 53 (and separation roller 55), even if non-feeding of sheet P is detected, it is not possible to determine whether the cause is pickup roller 54 or feed roller 53. In contrast, in this embodiment, when non-feeding of sheet P is detected, the retry mode is executed for both pickup roller 54 and feed roller 53, so such concerns do not arise.

[0042] <Variation 1> As shown in FIG. 9, the sheet feeding device 13 in the first modified example is also configured so that the retry mode is executed for both the pickup roller 54 and the feed roller 53 when non-feeding of the sheet P is detected. In the first modification, the roller diameter of the pickup roller 54 is different from the roller diameter of the feed roller 53. Therefore, even if the pickup roller 54 and the feed roller 53 are rotated for the same amount of time in the retry mode, they may not rotate by the same rotation angle. This phenomenon is particularly likely to occur when the pickup roller 54 and the feed roller 53 are gear-driven by the same drive source. 9, in this first modification, even if the retry mode is repeated at least twice, the orientation of the rotational direction of the pickup roller 54 at the initial start of feeding and the orientation of the pickup roller 54 in the rotational direction after each retry mode are all different, and the orientation of the rotational direction of the feed roller 53 at the initial start of feeding and the orientation of the rotational direction of the feed roller 53 after each retry mode are all different. Specifically, the orientations of the rotational directions of the pickup roller 54 and the feed roller 53 are reliably changed in this way so that the same contact portion does not come into contact with the sheet P, and the orientations of the rotational direction of the pickup roller 54 and the feed roller 53 are determined in consideration of the ratio of the roller diameters. This makes it possible to make it less likely that the sheet P will not be fed again when the pickup roller 54 or the feed roller 53 feeds the sheet P again, even if the sheet P has not been fed.

[0043] <Variation 2> As shown in FIG. 10, the control in the sheet feeding device 13 in the second variant is executed when the retry mode executed in step S4 of FIG. 7 is executed after step S5 when re-feeding is performed, rather than before step S5. More specifically, if it is determined in step S2 that a non-feed has occurred, the rotation of the pickup roller 54 is temporarily stopped, and if it is the first retry mode, step S5 is skipped and the first retry mode is executed, and then the non-feeded sheet P is re-fed (step S7). At this time, the conveying distance W in the re-feed is recorded in RAM 103 of the control unit 100. Furthermore, the first retry mode at this time is an open-loop control in which the pickup roller 54 is rotated at a predetermined rotation angle before the start of re-feeding. Then, the flow from step S2 onwards is repeated, but if it is determined in step S2 that a non-feed has occurred, it is determined in step S6 whether the conveying distance W recorded in RAM 103 exceeds a predetermined value A (step S5). As a result, if it is determined that the conveying distance W does not exceed the predetermined value A, it is determined that a jam has not occurred, and the flow from step S7 onwards is performed (a second re-feed is performed). On the other hand, if it is determined in step S5 that the conveying distance W exceeds the predetermined value A, it is determined that a jam has occurred, and no further re-feeding is performed, but a message that a jam has occurred is displayed on the operation display panel 80, and operation of the image forming apparatus 1 is stopped. Even when the control is performed in this manner, if a failure to feed the sheet P occurs, it is possible to make it difficult for the failure to occur when the pickup roller 54 (feed roller) re-feeds the sheet.

[0044] As described above, sheet feeding device 13 in the present embodiment is provided with pickup roller 54 (feed roller) that feeds sheet P placed on bottom plate 42 (placement section) in the feeding direction, non-feed detection sensor 70 (detection means) that can detect non-feeding of sheet P by pickup roller 54, and motor 90 (adjustment means) that can adjust the attitude of pickup roller 54 in the rotational direction. When non-feeding of sheet P by pickup roller 54 is detected by non-feed detection sensor 70 and re-feeding of sheet P by pickup roller 54 is repeatedly performed, a retry mode is executable that controls motor 90 so that the attitude of pickup roller 54 in the rotational direction at the start of a subsequent re-feed is changed from that at the start of a previous re-feed. This makes it possible to make it less likely that the sheet P will not be fed again when the pickup roller 54 (feed roller) feeds the sheet P again, even if the sheet P has not been fed.

[0045] In this embodiment, the present invention is applied to the sheet feeding device 13 installed on the lower level inside the image forming apparatus 1, but it goes without saying that the present invention can also be applied to the sheet feeding device 12 installed on the upper level inside the image forming apparatus 1, or the manual sheet feeding device 16 installed so as to be exposed to the outside of the image forming apparatus 1. Furthermore, in this embodiment, the present invention is applied to sheet feeding devices 12 and 13 installed in a monochrome image forming apparatus 1, but the present invention can naturally also be applied to sheet feeding devices installed in a color image forming apparatus. In addition, in this embodiment, the present invention is applied to sheet feeding devices 12, 13, and 16 built into image forming apparatus 1, but it goes without saying that the present invention can also be applied to sheet feeding devices (such as large-capacity paper feed banks) that are detachably installed in image forming apparatus 1. Furthermore, in this embodiment, the present invention is applied to sheet feeding devices 12, 13, and 16 installed in an electrophotographic image forming apparatus 1, but the application of the present invention is not limited to this, and the present invention can also be applied to sheet feeding devices installed in other types of image forming apparatuses (for example, inkjet image forming apparatuses, stencil printing machines, etc.). Furthermore, in this embodiment, the present invention is applied to an FRR type sheet feeding device 13 using a feed roller 53, a pickup roller 54, and a separation roller 55, but the present invention can also be applied to various types of sheet feeding devices, such as a pad type, as long as they are equipped with a feeding roller that contacts the sheet P to feed the sheet P. Furthermore, in this embodiment, in addition to the pickup roller 54, the feed roller 53 is also configured to be able to execute a retry mode in which, when a non-feed is detected and the rotation is stopped, the orientation of the rotation direction is changed from the orientation at the start of rotation (and the orientation at the start of the preceding re-feed). However, it is also possible to configure only the pickup roller 54 or only the feed roller 53 to be able to execute such a retry mode. In such a case, the pickup roller 54 and the feed roller 53 are configured to be driven separately. Even in such cases, the same effects as those of this embodiment can be obtained.

[0046] It is to be noted that the present invention is not limited to the present embodiment, and it is clear that the present embodiment can be appropriately modified within the scope of the technical concept of the present invention in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components can be any number, position, shape, etc. that is suitable for implementing the present invention.

[0047] In this specification, the term "sheet" is defined to include not only ordinary paper, but also all sheet-like recording media (including manuscripts), such as coated paper, label paper, OHP sheets, and film. [Explanation of symbols]

[0048] 1 Image forming apparatus (image forming apparatus main body, apparatus main body), 13 sheet feeding device, 42 bottom plate (placing part), 52 Feeding mechanism, 53 Feed roller, 54 pickup roller (feed roller), 55 Separation roller (separation member), 70 non-feed detection sensor (detection means, photosensor), 90 Motor (adjustment means), 100 control section, P seat.

[0049] The present invention can also be embodied in a combination of Supplementary Notes 1 to 14, for example, as follows. (Appendix 1) a feeding roller that feeds the sheet placed on the sheet placement section in a feeding direction; a detection means for detecting non-feeding of a sheet by the feeding roller; an adjustment means for adjusting the orientation of the feeding roller in the rotation direction; Equipped with A sheet feeding device characterized in that it is configured to be able to execute a retry mode that controls the adjustment means so that, when the detection means detects that the feeding roller has not fed a sheet and the feeding roller repeatedly re-feeds a single sheet, the orientation of the feeding roller in the rotational direction is displaced from that at the start of a previous re-feed to that at the start of a subsequent re-feed. (Appendix 2) a feeding roller that feeds the sheet placed on the sheet placement section in a feeding direction; a detection means for detecting non-feeding of a sheet by the feeding roller; an adjustment means for adjusting the orientation of the feeding roller in the rotation direction; Equipped with A sheet feeding device characterized in that it is configured to be able to execute a retry mode in which, when the detection means detects that the feeding roller has not fed a sheet and the feeding roller starts to feed the sheet again, the adjustment means is controlled so that the orientation of the feeding roller in the rotational direction is displaced from that at the time of the initial start of feeding. (Appendix 3) 3. The sheet feeding device according to claim 2, wherein the retry mode is executable every time the feeding roller repeatedly re-feeds one sheet. (Appendix 4) When the detection means detects non-feeding of the sheet by the feed roller during the re-feeding, When it is determined that the conveying distance of the sheet by the re-feeding exceeds a predetermined value, the re-feeding is not performed thereafter, A sheet feeding device as described in any one of Appendix 1 to Appendix 3, characterized in that when it is determined that the transport distance of the sheet due to the re-feeding does not exceed the predetermined value, the re-feeding is performed again. (Appendix 5) A sheet feeding device as described in any one of Appendix 1 to Appendix 4, characterized in that when the re-feeding of the sheet is repeated two or more times, the rotational direction posture at the start of the first feeding and the rotational direction posture after the retry mode for at least the second re-feeding are all different. (Appendix 6) A sheet feeding device according to any one of appendices 1 to 5, characterized in that the sheet transport distance assumed when re-feeding is assumed to be shorter than the sheet transport distance assumed when re-feeding is assumed to be shorter than the sheet transport distance assumed when re-feeding is assumed to be shorter than the sheet transport distance assumed when re-feeding is assumed to be shorter. (Appendix 7) A sheet feeding device according to any one of appendices 1 to 6, characterized in that when it is determined that a sheet has been transported beyond the sheet transport distance that would be expected if there had been no non-feeding since feeding by the feeding roller began, the device determines that the sheet has not been non-feeded. (Appendix 8) A sheet feeding device as described in any one of Appendix 1 to Appendix 7, characterized in that when the detection means detects that the feed roller does not feed a sheet during the first feeding and stops the rotation of the feed roller, the adjustment means is controlled so that the orientation of the feed roller in the rotational direction is displaced from that at the start of rotation. (Appendix 9) a pickup roller that contacts the uppermost sheet of the plurality of sheets stacked on the stacking section and feeds the uppermost sheet; 9. The sheet feeding device according to claim 1, wherein the feeding roller is the pickup roller. (Appendix 10) a pickup roller that contacts an uppermost sheet of the plurality of sheets stacked on the sheet stacking section and feeds the uppermost sheet; a feed roller disposed downstream of the pickup roller in a feeding direction and configured to feed the sheet fed by the pickup roller in the feeding direction; a separation roller in contact with the feed roller; Equipped with 10. The sheet feeding device according to any one of claims 1 to 9, wherein the feeding roller is the feed roller. (Appendix 11) a pickup roller that contacts an uppermost sheet of the plurality of sheets stacked on the sheet stacking section and feeds the uppermost sheet; a feed roller disposed downstream of the pickup roller in a feeding direction and configured to feed the sheet fed by the pickup roller in the feeding direction; a separation roller in contact with the feed roller; Equipped with 11. The sheet feeding device according to claim 1, wherein the feeding rollers are the pickup roller and the feed roller. (Appendix 12) The roller diameter of the pickup roller and the roller diameter of the feed roller are configured to be different, Even if the retry mode is repeated at least twice, The orientation of the pickup roller in the rotation direction at the time of the initial start of feeding and the orientation of the pickup roller in the rotation direction after each of the retry modes are different from each other, The sheet feeding device described in Appendix 11, characterized in that the orientation of the rotation direction of the feed roller when the feed roller first starts feeding and the orientation of the rotation direction of the feed roller after each of the retry modes are all different. (Appendix 13) The sheet feeding device according to any one of Supplementary Note 1 to Supplementary Note 12, wherein the detection means is a photosensor that is installed downstream in the feeding direction relative to the feeding roller and is capable of detecting the presence or absence of a sheet at that position. (Appendix 14) An image forming apparatus comprising the sheet feeding device according to any one of Supplementary Note 1 to Supplementary Note 13. [Prior art documents] [Patent documents]

[0050] [Patent Document 1] Patent Gazette No. 4944445

Claims

1. a feeding roller that feeds the sheet placed on the sheet placement section in a feeding direction; a detection means for detecting non-feeding of a sheet by the feeding roller; an adjustment means for adjusting the orientation of the feeding roller in the rotation direction; Equipped with A sheet feeding device characterized in that it is configured to be able to execute a retry mode that controls the adjustment means so that when the detection means detects that the feed roller has not fed a sheet and the feed roller repeatedly re-feeds a single sheet, the orientation of the feed roller in the rotational direction is displaced from that at the start of a previous re-feed to that at the start of a subsequent re-feed.

2. a feeding roller that feeds the sheet placed on the sheet placement section in a feeding direction; a detection means for detecting non-feeding of a sheet by the feeding roller; an adjustment means for adjusting the orientation of the feeding roller in the rotation direction; Equipped with A sheet feeding device characterized in that it is configured to be able to execute a retry mode in which, when the detection means detects that the feeding roller has not fed a sheet and the feeding roller starts to feed the sheet again, the adjustment means is controlled so that the orientation of the feeding roller in the rotational direction is displaced from that at the time of the initial start of feeding.

3. 3. The sheet feeding device according to claim 2, wherein the retry mode can be executed every time the feeding roller repeatedly re-feeds one sheet.

4. When the detection means detects non-feeding of the sheet by the feed roller during the re-feeding, When it is determined that the conveying distance of the sheet by the re-feeding exceeds a predetermined value, the re-feeding is not performed thereafter, 3. The sheet feeding apparatus according to claim 1, wherein when it is determined that the transport distance of the sheet by the re-feeding does not exceed the predetermined value, the re-feeding is performed again.

5. 3. The sheet feeding device according to claim 1, wherein when the re-feeding of the sheet is repeated two or more times, the orientation of the rotational direction at the start of the first feeding and the orientation of the rotational direction after the retry mode for at least the second re-feeding are all different.

6. 3. The sheet feeding device according to claim 1, wherein the sheet transport distance assumed when re-feeding is assumed to be shorter than the sheet transport distance assumed when non-feeding occurs during the first feeding.

7. 3. The sheet feeding device according to claim 1, wherein when it is determined that the sheet has been transported beyond the estimated transport distance that would be assumed if there had been no non-feeding since the start of feeding by the feeding roller, the device determines that the sheet has not been non-feeded.

8. 3. The sheet feeding device according to claim 1, wherein the detection means detects that the feed roller does not feed a sheet during the first feeding, and when the feed roller is stopped from rotating, the adjustment means is controlled so that the orientation of the feed roller in the rotational direction is displaced from that at the start of rotation.

9. a pickup roller that contacts an uppermost sheet of the plurality of sheets stacked on the stacking section and feeds the uppermost sheet; 3. The sheet feeding device according to claim 1, wherein the feeding roller is the pickup roller.

10. a pickup roller that contacts an uppermost sheet of the plurality of sheets stacked on the sheet stacking section and feeds the uppermost sheet; a feed roller disposed downstream of the pickup roller in a feeding direction and configured to feed the sheet fed by the pickup roller in the feeding direction; a separation roller in contact with the feed roller; Equipped with 3. The sheet feeding device according to claim 1, wherein the feeding roller is the feed roller.

11. a pickup roller that contacts an uppermost sheet of the plurality of sheets stacked on the sheet stacking section and feeds the uppermost sheet; a feed roller disposed downstream of the pickup roller in a feeding direction and configured to feed the sheet fed by the pickup roller in the feeding direction; a separation roller in contact with the feed roller; Equipped with 3. The sheet feeding device according to claim 1, wherein the feeding rollers are the pickup roller and the feed roller.

12. The roller diameter of the pickup roller and the roller diameter of the feed roller are configured to be different, Even if the retry mode is repeated at least twice, The orientation of the pickup roller in the rotation direction at the time of the initial start of feeding and the orientation of the pickup roller in the rotation direction after each of the retry modes are different from each other, 12. The sheet feeding device according to claim 11, wherein the orientation of the feed roller in the rotation direction at the time of initial start of feeding by the feed roller and the orientation of the feed roller in the rotation direction after each of the retry modes are different.

13. 3. The sheet feeding device according to claim 1, wherein the detecting means is a photosensor that is installed downstream of the feeding roller in the feeding direction and that can detect the presence or absence of a sheet at that position.

14. 3. An image forming apparatus comprising the sheet feeding device according to claim 1.

Images