Sheet feeding device, image forming apparatus

Abstract

To implement a function that measures the time required to feed the sheet after ensuring that the initial position of the sheet is not misaligned. [Solution] The displacement mechanism 21 can switch between a contact state in which the loaded sheet and the feeding rotating body 22 are in contact, and a separation state in which the loaded sheet and the feeding rotating body 22 are separated, by displacing the loaded sheet or the feeding rotating body 22. The return mechanism 28 performs a sheet return process to return the misaligned sheet to the upstream side in the sheet feeding direction when the displacement mechanism 21 switches from the contact state to the separation state. The processing device 8f derives the amount of misalignment of the target sheet. The control device 8d causes the return mechanism 28 to perform the sheet return process if the amount of misalignment satisfies the misalignment condition.

Description

Technical Field

[0001] The present invention relates to a sheet feeding device and an image forming apparatus that determine the sheet feeding state based on the time required for sheet feeding.

Background Art

[0002] An image forming apparatus includes a sheet conveyance device and a printing device that forms an image on a conveyed sheet. The sheet conveyance device includes a sheet feeding device that feeds the uppermost sheet in the stacked sheets to a conveyance path, and a plurality of pairs of conveyance rollers that convey the sheet along the conveyance path.

[0003] The sheet feeding device includes a sheet detection device that detects the sheet being fed to the conveyance path. It is known that the image forming apparatus measures the sheet feeding speed based on the detection result of the sheet detection device (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the sheet feeding device, a measurement process for measuring the time from when sheet feeding is started until the sheet is detected by the sheet detection device is executed. The measurement time obtained by the measurement process represents the sheet feeding state.

[0006] For example, when a delay in sheet feeding occurs due to deterioration of components in contact with the sheet, etc., the delay time is reflected in the measurement time. The feeding delay affects the sheet interval.

[0007] On the other hand, when the target sheet is fed, other sheets overlapping the target sheet may move downstream from their initial reference position in the sheet feeding direction by following the target sheet. The deviation of the following sheet from the initial reference position affects the measurement time when the following sheet is fed as the target sheet.

[0008] Therefore, in order to correctly understand the sheet feeding state in the sheet feeding device, it is important to obtain the measurement time for the target sheet as the reference time when the target sheet is not deviating from the initial reference position.

[0009] Therefore, it is desirable that the sheet feeding device be equipped with a function to obtain the measurement time for the target sheet after ensuring that the target sheet is not deviated from its initial reference position.

[0010] The object of the present invention is to provide a sheet feeding device and an image forming apparatus that have a function to measure the time required to feed the sheet after creating a situation in which the initial position of the sheet is not misaligned. [Means for solving the problem]

[0011] A sheet feeding device according to one aspect of the present invention comprises a feeding mechanism, a displacement mechanism, a sheet detection device, a timing device, a return mechanism, a processing device, and a control device. The feeding mechanism has a feeding rotating body that contacts the upper surface of the topmost sheet in the stacked sheets, and performs a feeding process to feed each sheet from the stacked sheets to a transport path by rotating the feeding rotating body. The displacement mechanism is a mechanism that can switch between a contact state in which the stacked sheets and the feeding rotating body are in contact and a separation state in which the stacked sheets and the feeding rotating body are separated by displacing the stacked sheets or the feeding rotating body. The sheet detection device detects each sheet at a position downstream of the feeding rotating body in the sheet feeding direction. The timing device measures the elapsed time from the time when the feeding process for each sheet is started until the time when each sheet is detected by the sheet detection device. The return mechanism performs a sheet return process to return any misaligned sheets that have shifted downstream in the sheet feeding direction relative to their initial reference position to the upstream side in the sheet feeding direction when the displacement mechanism switches from the contact state to the separation state. The processing device derives a positional displacement amount representing the amount of misalignment of the target sheet relative to its initial reference position at the time the feeding process for the target sheet begins, based on a preset reference feeding time and a target measurement time measured by the timing device for the target sheet fed by the feeding process. The control device causes the return mechanism to perform the sheet return process if the positional displacement amount satisfies a predetermined positional displacement condition.

[0012] An image forming apparatus according to another aspect of the present invention comprises a sheet feeding device and a printing device that forms an image on each sheet fed by the sheet feeding device. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a sheet feeding device and an image forming apparatus that have a function to measure the time required to feed the sheet after creating a situation in which the initial position of the sheet is not misaligned. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a configuration diagram of an image forming apparatus according to an embodiment. [Figure 2] Figure 2 is a block diagram showing the configuration of the control device in the image forming apparatus according to the embodiment. [Figure 3] Figure 3 is a diagram showing the configuration of the sheet feeding device in the image forming apparatus according to the embodiment. [Figure 4] Figure 4 shows the sheet feeding apparatus in the image forming apparatus according to the embodiment before the feeding process is started. [Figure 5] Figure 5 shows a sheet feeding device in a sheet-cut state in an image forming apparatus according to an embodiment. [Figure 6] Figure 6 shows a sheet feeding device in an image forming apparatus according to an embodiment, during the return process. [Figure 7] Figure 7 shows the sheet feeding device in the image forming apparatus according to the embodiment after the return process has been completed. [Figure 8] Figure 8 is a flowchart showing an example of the sheet feeding control procedure in an image forming apparatus according to this embodiment. [Figure 9] Figure 9 is a flowchart showing an example of the procedure for the first return control in the image forming apparatus according to this embodiment. [Figure 10] Figure 10 is a flowchart showing an example of the procedure for determining component degradation in an image forming apparatus according to an embodiment. [Figure 11] Figure 11 is a flowchart showing an example of the procedure for the second return control in the image forming apparatus according to the embodiment. [Figure 12] Figure 12 shows a first example of the relationship between the target measurement time, target feeding time, and delay time in an image forming apparatus according to an embodiment. [Figure 13] Figure 13 shows a second example of the relationship between the target measurement time, target feeding time, and delay time in an image forming apparatus according to an embodiment. [Figure 14]FIG. 14 is a diagram showing a third example of the relationship among the target measurement time, the target feeding time, and the delay time in the image forming apparatus according to the embodiment. [Figure 15] FIG. 15 is a configuration diagram of a sheet feeding device in the image forming apparatus according to the first modification. [Figure 16] FIG. 16 is a block diagram showing the configuration of a control device in the image forming apparatus according to the second modification.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are merely examples of embodying the present invention and do not limit the technical scope of the present invention.

[0016] [Configuration of Image Forming Apparatus 10] The image forming apparatus 10 according to the embodiment includes a sheet feeding device 2, a sheet conveying device 3, and a printing device 4. Further, the image forming apparatus 10 also includes a control device 8, an operation device 801, a display device 802, and the like.

[0017] Furthermore, the image forming apparatus 10 includes a main housing 1 that houses the sheet feeding device 2, the sheet conveying device 3, and the printing device 4. The main housing 1 includes a lower housing 1a that forms the housing of the sheet feeding device 2.

[0018] The sheet feeding device 2 includes a sheet cassette 200, a feeding mechanism 20, a lift mechanism 21, and a fed sheet detection device 25 (see FIG. 1). The feeding mechanism 20 includes a pickup roller 22, a delivery roller 23, and a retard roller 24.

[0019] The sheet cassette 200 accommodates stacked sheets 90 and is detachably attached to the lower housing 1a. The sheet cassette 200 is an example of a sheet storage unit.

[0020] The pickup roller 22 and the delivery roller 23 are each rotatably supported and spaced apart. The pickup roller 22 contacts the upper surface of the top sheet on the loading sheet 90. The feeding mechanism 20 further includes a feeding motor 230 that rotates the pickup roller 22 and the delivery roller 23 (see Figure 3).

[0021] The feeding mechanism 20 performs the feeding process by rotating the pickup roller 22 and the delivery roller 23. The feeding process involves feeding each of the sheets 9 from the loading sheet 90 to the transport path 30. The transport path 30 is the passage for each of the sheets 9.

[0022] The feed roller 23 and retard roller 24 are located in the area between the sheet cassette 200 and the transport path 30. The retard roller 24 is located below the feed roller 23 and faces the feed roller 23. The retard roller 24 forms a nip between itself and the feed roller 23, sandwiching each sheet 9.

[0023] In the sheet feeding device 2, the sheet feeding direction D1 is the direction from the sheet cassette 200 to the transport path 30 (see Figure 1). The delivery roller 23 is positioned downstream of the pickup roller 22 in the sheet feeding direction D1 (see Figures 1 and 3).

[0024] The pickup roller 22 is an example of a feeding rotating body. The delivery roller 23 is an example of a delivery rotating body. The delivery roller 23 is positioned downstream of the pickup roller 22 in the sheet feeding direction D1 and rotates together with the pickup roller 22.

[0025] The retard roller 24 is rotatably supported. The feeding mechanism 20 further includes a torque limiter 24a connected to the rotation axis of the retard roller 24, and a spring 241 that biases the retard roller 24 toward the feed roller 23 (see Figure 3).

[0026] When the feeding process is performed, a torque DR1 in the forward rotation direction acts on the retard roller 24 from either the rotating feed roller 23 or the sheet 9 moving toward the conveying path 30.

[0027] The torque limiter 24a restricts the rotation of the retard roller 24 in the forward rotation direction DR1 when the torque acting on the retard roller 24 in the forward rotation direction DR1 is less than or equal to the rated torque (see Figure 3).

[0028] The retard roller 24 blocks the accompanying sheets by contacting the leading edge of one or more accompanying sheets that are fed out with each sheet 9 when the feeding process is performed. In this way, the retard roller 24 separates the accompanying sheets from each sheet 9. The accompanying sheets are fed out from the sheet cassette 200 so that they overlap the underside of the top sheet on the stacked sheet 90.

[0029] Furthermore, if the torque acting on the retard roller 24 from either the rotating discharge roller 23 or the sheet 9 moving toward the conveyor path 30 exceeds the rated torque of the torque limiter 24a, the retard roller 24 rotates in the forward rotation direction DR1. This prevents either the discharge roller 23 or the sheet 9 from receiving excessive frictional force from the retard roller 24.

[0030] The retard roller 24 is an example of a separating member that separates the auxiliary sheet from the uppermost sheet of the loading sheet 90. A non-rotating separating pad may be used as the separating member instead of the retard roller 24.

[0031] In the following description, the position of each sheet 9 when its leading edge is aligned with the cassette front wall surface 200a is referred to as the initial reference position P1 (see Figures 1 and 3). The cassette front wall surface 200a is the inner wall surface of the downstream end of the sheet cassette 200 in the sheet feeding direction D1. The position between the delivery roller 23 and the retard roller 24 is referred to as the separation position P2 (see Figures 1 and 3).

[0032] The lift mechanism 21 is located within the sheet cassette 200 and is supported by the sheet cassette 200. The lift mechanism 21 supports the loading sheet 90 so that it can be raised and lowered.

[0033] The lift mechanism 21 is a mechanism for lifting the loading sheet 90 from a separation position to a contact position. The separation position is the position where the upper surface of the top sheet of the loading sheet 90 is separated from the pickup roller 22. The contact position is the position where the upper surface of the top sheet of the loading sheet 90 is in contact with the pickup roller 22.

[0034] The lift mechanism 21 comprises a lift plate 211 and a push-up plate 212. The lift plate 211 is rotatably supported around a pivot axis 211a, which is positioned along the bottom plate of the sheet cassette 200. That is, the lift plate 211 is rotatable up and down around the pivot axis 211a.

[0035] The loading sheet 90 is placed on the lift plate 211. When the lift plate 211 rotates upward, the loading sheet 90 rotates upward, and when the lift plate 211 rotates downward, the loading sheet 90 rotates downward.

[0036] The push-up plate 212 is positioned below the lift plate 211 and is supported so as to be rotatable around a pivot shaft 212a that is positioned along the bottom plate of the sheet cassette 200. In other words, the push-up plate 212 is rotatable up and down around the pivot shaft 212a.

[0037] The push-up plate 212 rotates in a first rotational direction by the driving force of a motor (not shown), thereby pushing the lift plate 211 and the loaded sheet 90 on the lift plate 211 upward. That is, the lift mechanism 21 lifts the loaded sheet 90 on the lift plate 211 from the separated position to the contact position by rotating the push-up plate 212 in the first rotational direction.

[0038] Meanwhile, the push-up plate 212 rotates in the second rotational direction by the driving force of the motor, thereby lowering the lift plate 211 and the loading sheet 90 on the lift plate 211. In other words, the lift mechanism 21 lowers the loading sheet 90 on the lift plate 211 from the contact position to the separation position by rotating the push-up plate 212 in the second rotational direction.

[0039] The lift mechanism 21 is an example of a displacement mechanism for displacing the loading sheet 90. The lift mechanism 21 can switch between a contact state in which the loading sheet 90 and the pickup roller 22 are in contact, and a separation state in which the loading sheet 90 and the pickup roller 22 are separated, by raising and lowering the loading sheet 90.

[0040] In the lift mechanism 21, the state in which the loading sheet 90 is lifted to the contact position is the contact state, and the state in which the loading sheet 90 is lowered to the separation position is the separation state. In the lift mechanism 21, the operation of lowering the lift plate 211 by rotating the push-up plate 212 in the second rotational direction is a switching operation from the contact state to the separation state.

[0041] In the following description, the operation of the lift mechanism 21 that raises the loading sheet 90 to the contact position by raising the lift plate 211 will be referred to as the lift plate raising operation. The lift plate raising operation is the operation in which the lift mechanism 21 switches from the separation state to the contact state.

[0042] Similarly, the operation of the lift mechanism 21 in which the lift plate 211 is lowered to move the loading sheet 90 from the contact position to the separation position is referred to as the lift plate lowering operation. The lift plate lowering operation is the operation in which the lift mechanism 21 switches from the contact state to the separation state.

[0043] The feed sheet detection device 25 detects each sheet 9 being fed by the feeding process at a detection position P3 downstream of the feed roller 23 in the sheet feeding direction D1. For example, the feed sheet detection device 25 includes a pivotably supported actuator and a photosensor that detects when the actuator swings. The actuator swings by coming into contact with each sheet 9 passing through the detection position P3.

[0044] The sheet feeding detection device 25 may also be a transmissive or reflective photosensor that detects each sheet 9 passing through the detection position P3.

[0045] The sheet feeding device 2 further includes a mounting detection device 26 located on the lower housing 1a (see Figure 1). The mounting detection device 26 detects whether the sheet cassette 200 is in a mounted state, mounted in the lower housing 1a, or in an unmounted state, pulled out from the lower housing 1a.

[0046] For example, the mounting detection device 26 is a reflective photosensor or microswitch that detects a portion of the sheet cassette 200 in the mounted state.

[0047] When the seat cassette 200 is in the aforementioned mounting state, the lift mechanism 21 can lift the loading sheet 90 to the aforementioned contact position.

[0048] The sheet cassette 200 further comprises an end cursor 213 and a pair of side cursors 214. The end cursor 213 is provided to be movable along the sheet feeding direction D1. The end cursor 213 is positioned along the rear end of the loaded sheet 90 placed on the lift plate 211. This prevents the loaded sheet 90 from shifting upstream of the initial reference position P1 in the sheet feeding direction D1.

[0049] A pair of side cursors 214 are arranged to be interlocked so as to move toward or away from each other along the width direction D2, which is perpendicular to the sheet feeding direction D1.

[0050] The pair of side cursors 214 are positioned along both ends of the loading sheet 90 placed on the lift plate 211 in the width direction D2. This prevents the loading sheet 90 from shifting from a specific position in the width direction D2.

[0051] The sheet conveying device 3 conveys each of the sheets 9 supplied by the sheet feeding device 2 along the conveying path 30. In this embodiment, the sheet conveying device 3 includes a plurality of pairs of conveying rollers 31 and a conveying sheet detection device 32 arranged along the conveying path 30.

[0052] Multiple sets of conveying rollers 31 convey each sheet 9 by rotating individually. Each set of conveying rollers 31 includes a resist roller set 31a and a discharge roller set 31b.

[0053] The resist roller pair 31a is positioned at resist position P4 in the transport path 30. The discharge roller pair 31b is positioned at the end of the transport path 30.

[0054] The resist roller pair 31a pauses each sheet 9 fed by the sheet feeder 2 at the resist position P4, and then sends it to the print position P5 in the transport path 30.

[0055] The transport sheet detection device 32 detects each sheet 9 as it moves towards the resist position P4 after being fed into the transport path 30 by the sheet feeding device 2. The transport sheet detection device 32 has the same configuration as the feeding sheet detection device 25.

[0056] The discharge roller pair 31b discharges each sheet 9 that has passed through print position P5 from the transport path 30 to the discharge tray 101. As will be described later, an image is formed on each sheet 9 at print position P5.

[0057] The printing device 4 forms an image on each of the sheets 9 transported by the sheet transport device 3. That is, the printing device 4 forms an image on each of the sheets 9 supplied by the sheet feeding device 2. The printing device 4 forms an image on each of the sheets 9 at the printing position P5 in the transport path 30.

[0058] In the example shown in Figure 1, the printing device 4 forms an image on each of the sheets 9 using an electrophotographic method. In this case, the printing device 4 includes a light scanning unit 40, one or more image forming units 4x, a transfer device 44, and a fixing device 46.

[0059] In the example shown in Figure 1, the printing apparatus 4 includes multiple image forming units 4x corresponding to multiple development colors. Each image forming unit 4x includes a drum-shaped photoreceptor 41, a charging device 42, a developing device 43, and a drum cleaning device 45. For example, the multiple development colors are cyan, yellow, magenta, and black.

[0060] Furthermore, the transfer apparatus 44 includes an intermediate transfer belt 440, a plurality of primary transfer devices 441 corresponding to a plurality of image forming units 4x, a secondary transfer device 442, and a belt cleaning device 443.

[0061] In each of the image forming units 4x, the charging device 42 charges the surface of the photoreceptor 41. The optical scanning unit 40 forms an electrostatic latent image on the surface of the photoreceptor 41 in each of the image forming units 4x by scanning with laser light.

[0062] In each of the image forming units 4x, the developing device 43 develops the electrostatic latent image into a toner image by supplying toner to the surface of the photoreceptor 41.

[0063] The primary transfer device 441 transfers the toner images on the surface of the photoreceptor 41 of each image forming unit 4x to the surface of the intermediate transfer belt 440. As a result, the toner images of the multiple developing colors are transferred to the surface of the intermediate transfer belt 440. At the print position P5, the primary transfer device 441 transfers the toner images on the surface of the intermediate transfer belt 440 to each of the sheets 9. The fixing device 46 fixes the toner images transferred to each of the sheets 9 by heating and pressurizing them.

[0064] In each of the image forming units 4x, the drum cleaning device 45 removes waste toner remaining on the surface of the photoreceptor 41. The belt cleaning device 443 removes waste toner remaining on the surface of the intermediate transfer belt 440.

[0065] The printing device 4 may be a device that forms images on each of the sheets 9 using a method other than electrophotography. For example, the printing device 4 may be a device that forms images on each of the sheets 9 using an inkjet method.

[0066] If an inkjet printing device 4 is used, the sheet transport device 3 may include a belt transport device that transports each sheet 9 by a rotating endless belt.

[0067] The operating device 801 is a device that accepts human input. The operating device 801 includes, for example, operating buttons and a touch panel. The display device 802 is a device that displays information. The display device 802 includes, for example, a panel display device such as a liquid crystal display unit.

[0068] The control device 8 performs various data processing operations. Furthermore, the control device 8 controls equipment such as the sheet feeding device 2, the sheet transport device 3, the printing device 4, and the display device 802.

[0069] As shown in Figure 3, the control device 8 includes a CPU (Central Processing Unit) 81, a RAM (Random Access Memory) 82, a secondary storage device 83, and peripheral devices such as a signal interface 84. Furthermore, the control device 8 also includes a communication device 85.

[0070] The CPU 81 is a processor that performs various data processing and control by executing computer programs. The RAM 82 is a computer-readable volatile memory. The RAM 82 temporarily stores the computer programs executed by the CPU 81 and the data that the CPU 81 outputs and references during the process of performing various processes.

[0071] The secondary storage device 83 is a computer-readable, non-volatile storage device. The secondary storage device 83 is capable of storing and updating the computer program and various types of data. For example, flash memory, a hard disk drive, or both may be used as the secondary storage device 83.

[0072] The signal interface 84 converts signals output by various sensors into digital data and transmits the converted digital data to the CPU 81. Furthermore, the signal interface 84 converts control commands output by the CPU 81 into control signals and transmits the control signals to the controlled device.

[0073] The communication device 85 performs communication with other devices such as a host device via a communication network such as a LAN. The CPU 81 sends and receives data with the other devices via the communication device 85.

[0074] The CPU 81 includes a plurality of processing modules that are realized by executing the computer program. The plurality of processing modules include a feed control unit 8a, a transport control unit 8b, and a print control unit 8c, among others.

[0075] The feed control unit 8a performs data processing and control related to the sheet feeding device 2. The feed control unit 8a of the CPU 81 constitutes a part of the sheet feeding device 2.

[0076] The transport control unit 8b performs data processing and control related to the sheet transport device 3. The transport control unit 8b of the CPU 81 constitutes a part of the sheet transport device 3.

[0077] The print control unit 8c performs data processing and control related to the printing device 4. The print control unit 8c of the CPU 81 constitutes a part of the printing device 4.

[0078] The supply control unit 8a includes a main processing unit 8d, a timing processing unit 8e, and a state determination unit 8f, among others.

[0079] The main processing unit 8d controls the start and end of the feeding process by controlling the operation and stopping of the feeding motor 230.

[0080] For example, when a print request is input through the operating device 801 or the communication device 85, the main processing unit 8d activates the feed motor 230 to start the feed mechanism 20.

[0081] The print request is either a request to execute a single print process or a request to execute a series of print processes. The single print process is the process of forming an image on one sheet 9. The series of print processes is the process of forming images sequentially on multiple sheets 9.

[0082] The timing processing unit 8e performs a first timing process that measures the elapsed time from the time when the feeding process for each sheet 9 is started until the time when each sheet 9 is detected by the feeding sheet detection device 25. In this embodiment, the time when the feeding motor 230 starts operating is the time when the feeding process is started.

[0083] The timing processing unit 8e is an example of a timing device that performs the first timing process. The timing device may be implemented by other processors such as a DSP (Digital Signal Processor) or by circuits such as an ASIC (Application Specific Integrated Circuit).

[0084] Furthermore, the timing processing unit 8e also performs a second timing process, which measures the elapsed time from the moment each sheet 9 is detected by the sheet feeding detection device 25.

[0085] If the print request is a request to execute the continuous print process, the main processing unit 8d controls the timing of the start of the second and subsequent feeding processes based on the measurement time of the second timing process. As a result, each sheet 9 is fed to the transport path 30 at appropriate intervals.

[0086] The state determination unit 8f executes a process to determine the feeding status of each sheet 9 by the sheet feeding device 2. In this embodiment, the state determination unit 8f determines the feeding status of each sheet 9 by the sheet feeding device 2 based on the measurement time of the first timing process.

[0087] The print control unit 8c controls the process of forming the electrostatic latent image on the surface of the photoreceptor 41 of each of the multiple image forming units 4x by controlling the optical scanning unit 40. In this way, the print control unit 8c controls the timing at which the toner image is formed on the surface of the photoreceptor 41 of each of the multiple image forming units 4x.

[0088] The transport control unit 8b stops the rotation of the resist roller pair 31a in response to the detection of each sheet 9 by the transport sheet detection device 32, and then rotates the resist roller pair 31a in accordance with the timing at which the toner image is formed in each of the multiple image forming units 4x. As a result, the transport control unit 8b executes control to feed each of the sheets 9 from the resist position P4 to the print position P5 in synchronization with the timing at which the toner image is formed in each of the multiple image forming units 4x.

[0089] The sheet feeding device 2 further includes a sheet break detection device 27 (see Figures 3 and 5). The sheet break detection device 27 detects when there are no sheets 9 remaining on the lift plate 211 that can be fed by the feeding mechanism 20.

[0090] In this embodiment, the sheet break detection device 27 comprises a swinging member 271 that is swingably supported above the lift plate 211 and an object detection sensor 272 (see Figure 3). The swinging member 271 has a rotatably supported shaft portion 271a and an arm portion 271b and a detection portion 271c extending from the shaft portion 271a, respectively.

[0091] The oscillating member 271 is pivotable around the shaft portion 271a. The arm portion 271b extends from the shaft portion 271a toward the lift plate 211.

[0092] When one or more sheets 9 are present on the lift plate 211, the arm portion 271b contacts the upper surface of one or more sheets 9 on the lift plate 211 (see Figure 3).

[0093] In the following description, the position of the rocking member 271 when the arm portion 271b is in contact with the upper surface of one or more sheets 9 will be referred to as the first position. The first position is the position of the rocking member 271 when no sheet tearing occurs.

[0094] An opening 211b is formed in the lift plate 211 (see Figure 3). If the sheet is torn, the arm portion 271b penetrates the lift plate 211 through the opening 211b (see Figure 5).

[0095] In the following description, the position of the oscillating member 271 when the arm portion 271b penetrates the lift plate 211 through the opening 211b will be referred to as the second position. The second position is the position of the oscillating member 271 when the sheet tear occurs.

[0096] The detected part 271c is displaced in accordance with the oscillation of the oscillating member 271. The object detection sensor 272 detects the detected part 271c when the oscillating member 271 is in either the first or second position.

[0097] In the example shown in Figure 3, the object detection sensor 272 detects the detected portion 271c when the oscillating member 271 is in the first position. When the oscillating member 271 is in the second position, the detected portion 271c moves out of the area detected by the object detection sensor 272 (see Figure 5).

[0098] When the lift mechanism 21 is lifting the loading sheet 90, the detection signal from the object detection sensor 272 indicates whether or not the sheet has been torn. In the example shown in Figures 3 and 5, the object detection sensor 272 detects the detected part 271c when the sheet has not been torn, and does not detect the detected part 271c when the sheet has been torn.

[0099] In the following description, one sheet of the stacking sheet 90 that is subject to the paper feeding process will be referred to as the target sheet 9a (see Figures 3 and 4). The target sheet 9a is the topmost sheet of the stacking sheet 90. The target sheet 9a is also the sheet subject to the first timing process and the second timing process.

[0100] Furthermore, the sheet that is subjected to the feeding process after the target sheet 9a in the loading sheet 90 is referred to as the next sheet 9b (see Figure 3). The next sheet 9b is the second sheet from the top in the loading sheet 90.

[0101] By the way, in the sheet feeding device 2, the measurement time obtained by the first timing process of the timing processing unit 8e represents the feeding status of each sheet 9.

[0102] For example, if the feeding of each sheet 9 is delayed due to deterioration of the components in contact with each sheet 9, the delay time will be reflected in the measurement time. This feeding delay will affect the spacing between each sheet 9.

[0103] On the other hand, when the target sheet 9a is fed, other sheets that overlap the target sheet 9a may move downstream from the initial reference position P1 in the sheet feeding direction D1 by following the target sheet 9a. The deviation of the following sheet from the initial reference position P1 affects the measurement time when the following sheet is fed as the target sheet 9a.

[0104] Therefore, in order to correctly understand the feeding status of each sheet 9 in the sheet feeding device 2, it is important to obtain the measurement time for the target sheet 9a when the target sheet 9a is not deviating from the initial reference position P1 as the reference time.

[0105] Therefore, it is desirable that the sheet feeding device 2 implements a function that ensures the target sheet 9a is not deviated from the initial reference position P1.

[0106] Furthermore, it is desirable that the sheet feeding device 2 be equipped with a function to obtain the measurement time for the target sheet 9a after ensuring that the target sheet 9a is not deviated from its initial reference position P1.

[0107] The sheet feeding device 2 includes a return mechanism 28, which is a mechanism for ensuring that the target sheet 9a is not deviated from the initial reference position P1 (see Figures 3, 6, and 7).

[0108] The return mechanism 28 performs a sheet return process when the lift mechanism 21 performs the lift plate lowering operation. The sheet return process is the process of returning misaligned sheets 90 that have shifted downstream in the sheet feeding direction D1 relative to the initial reference position P1 to the upstream side in the sheet feeding direction D1 (see Figures 6 and 7). Figure 6 shows the state in which the sheet return process is being performed, and Figure 7 shows the state after the sheet return process has been performed.

[0109] [Configuration of the return mechanism 28] The return mechanism 28 includes a retractor 281 that is rotatably supported around a shaft 28a, and a drive mechanism 282 that rotates the retractor 281 (see Figure 3).

[0110] The shaft portion 28a is positioned above the pre-separation path, which is the path for each sheet 9 from the initial reference position P1 to the separation position P2. The shaft portion 28a may also be positioned below the pre-separation path. The pre-separation path is an example of the path from the initial reference position P1 to the transport path 30.

[0111] The repelling member 281 is formed extending from the shaft portion 28a in one or more directions. In this embodiment, the repelling member 281 is a plate-shaped member formed extending from the shaft portion 28a in two directions.

[0112] For example, the repulsive member 281 is an elastic member whose main material is rubber or elastomer resin.

[0113] As the drive mechanism 282 rotates the repelling member 281, a portion of the repelling member 281 passes through the pre-separation path from the downstream side to the upstream side in the sheet feeding direction D1. The rotating repelling member 281 repels the misaligned sheet toward the upstream side in the sheet feeding direction D1, thereby returning the misaligned sheet to the upstream side in the sheet feeding direction D1 (see Figures 6 and 7).

[0114] The return mechanism 28 further comprises a biasing adjustment mechanism 280. The biasing adjustment mechanism 280 reduces the bias of the retard roller 24 toward the feed roller 23 or releases the bias of the retard roller 24 toward the feed roller 23 when the sheet return process is performed.

[0115] The retard roller 24 is biased toward the feed roller 23 by a spring 241. In this embodiment, the bias adjustment mechanism 280 releases the bias of the retard roller 24 toward the feed roller 23 (see Figures 6 and 7).

[0116] In the following description, the action of the biasing adjustment mechanism 280 to reduce or release the biasing of the retard roller 24 toward the feed roller 23 will be referred to as the counter-biasing action. Conversely, the action of the biasing adjustment mechanism 280 to bias the retard roller 24 toward the feed roller 23 will be referred to as the biasing action.

[0117] In this embodiment, the feeding mechanism 20 further comprises a movable support 242 that is supported so as to be able to move toward and away from the discharge roller 23 (see Figure 3). The movable support 242 supports the retard roller 24 and the spring 241.

[0118] The retard roller 24, spring 241, and movable support 242 constitute a retard unit 240 that can move toward and away from the discharge roller 23 (see Figure 3).

[0119] The biasing adjustment mechanism 280 moves the retard unit 240 toward the discharge roller 23 or toward the discharge roller 23. For example, the biasing adjustment mechanism 280 is an actuator such as a solenoid.

[0120] The biasing adjustment mechanism 280 releases the biasing of the retard roller 24 when the lift mechanism 21 performs the lift plate lowering operation. The drive mechanism 282 rotates the recoil member 281 when the lift mechanism 21 performs the lift plate lowering operation.

[0121] In the return mechanism 28, the process by which the drive mechanism 282 rotates the repulsion member 281 is the sheet return process. That is, the biasing adjustment mechanism 280 releases the biasing of the retard roller 24 directed toward the feed roller 23 when the sheet return process is executed.

[0122] By releasing the biasing force of the retard roller 24, the biasing force adjustment mechanism 280 ensures that even if the leading edge of the accompanying sheet has reached downstream of the separation position P2 in the sheet feeding direction D1, the accompanying sheet moves smoothly toward the initial reference position P1 through the sheet return process.

[0123] In the sheet feeding device 2, the feeding control unit 8a performs sheet feeding control, which will be described later (see Figure 8).

[0124] [Sheet feeding control] The following describes an example of the sheet feeding control procedure with reference to the flowchart shown in Figure 8. The sheet feeding control is performed by the feeding control unit 8a.

[0125] The sheet feeding control procedure described above is an example of a procedure for implementing a sheet feeding control method for controlling the sheet feeding device 2. The sheet feeding control procedure includes a procedure for implementing a sheet feeding state determination method.

[0126] The CPU 81, including the feed control unit 8a, is an example of a control device that implements the sheet feed control method and a processing device that implements the sheet feed state determination method. The main processing unit 8d starts the sheet feed control when the print request is input through the operating device 801 or the communication device 85.

[0127] In the following description, S101, S102, ... represent identification codes for multiple processes in the sheet feeding control. In the sheet feeding control, the process of process S101 is executed first.

[0128] <Process S101> In step S101, the main processing unit 8d obtains pre-registered sheet size information from the secondary storage device 83. The sheet size information represents the size of the loading sheets 90 stored in the sheet cassette 200.

[0129] For example, the sheet size information includes standard size information selected from a plurality of standard size candidates and sheet orientation information representing the orientation of the loading sheet 90. The standard size information is information that specifies the vertical and horizontal dimensions of the loading sheet 90, and the sheet orientation information represents whether the length of the loading sheet 90 in the sheet feeding direction D1 is the vertical or horizontal dimension.

[0130] That is, the sheet size information includes sheet length information representing the length in the sheet feeding direction D1 of the loaded sheet 90 housed in the sheet cassette 200. The length represented by the sheet length information is the vertical dimension or the horizontal dimension in the standard size information.

[0131] The main processing unit 8d inputs the sheet size information in advance via the operating device 801 or the communication device 85 and registers it in the secondary storage device 83.

[0132] After executing the process in step S101, the main processing unit 8d moves the process to step S102.

[0133] <Process S102> In step S102, the main processing unit 8d determines whether the feeding timing has arrived or not.

[0134] For example, the feeding timing is either the initial feeding timing or the subsequent feeding timing. The initial feeding timing is the timing after the print request has been input and the printer 4 has finished preparing to operate.

[0135] The subsequent feeding timing is the timing at which the feeding of the second and subsequent sheets 9 begins when the print request is a request for the continuous printing process.

[0136] Specifically, the subsequent feeding timing is the timing when the second measurement time corresponding to the previous feeding process reaches the feeding waiting time. The feeding waiting time is the time required from the moment the leading edge of each sheet 9 reaches the detection position P3 until the rear end of each sheet 9 exceeds a predetermined distance from the cassette front wall surface 200a.

[0137] In process S101, the main processing unit 8d sets a reference waiting time, which is one of a plurality of pre-set candidate waiting times corresponding to the sheet length information, as the feed waiting time.

[0138] The main processing unit 8d waits until it is determined that the feeding timing has arrived. When it is determined that the feeding timing has arrived, the main processing unit 8d moves the process to step S103.

[0139] <Process S103> In step S103, the main processing unit 8d causes the feeding mechanism 20 to start the feeding process. As a result, the pickup roller 22 and the delivery roller 23 rotate, and the target sheet 9a on the loading sheet 90 is fed from the lift plate 211 toward the transport path 30 (see Figure 3).

[0140] Furthermore, when the feeding process is started in step S103, the timing processing unit 8e starts the first timing process.

[0141] After executing the process in step S103, the main processing unit 8d moves the process to step S104.

[0142] <Process S104> In step S104, the timing processing unit 8e moves the process to step S107 when the sheet feeding detection device 25 transitions from a non-detection state to a sheet detection state.

[0143] The timing processing unit 8e terminates the first timing process when the feed sheet detection device 25 transitions to the sheet detection state. As a result, the timing processing unit 8e determines the target measurement time T1a, which is the result of the first timing process for the target sheet 9a (see Figures 12-14).

[0144] Figures 12-14 show an example of the change in the target measurement time T1a according to the number of feeding cycles when the feeding process is repeated.

[0145] In step S104, if the feeding sheet detection device 25 does not transition from the sheet non-detection state to the sheet detection state, the timing processing unit 8e proceeds to step S105. In this case, the timing processing unit 8e continues the first timing process.

[0146] <Process S105> In step S105, the timing processing unit 8e selects the next process depending on whether the timing time from the first timing process exceeds a preset upper limit. The upper limit is the time used to detect an empty feed state in which the feeding mechanism 20 cannot feed the target sheet 9a.

[0147] The timing processing unit 8e moves the process to step S104 if the timing time from the first timing process does not exceed the upper limit time. As a result, the timing processing unit 8e continues the first timing process until the feed sheet detection device 25 transitions from the sheet non-detection state to the sheet detection state, provided that the timing time from the first timing process does not exceed the upper limit time.

[0148] On the other hand, if the timing time from the first timing process exceeds the upper limit time while the feeding sheet detection device 25 does not transition to the sheet detection state, the timing processing unit 8e moves the process to step S106.

[0149] <Process S106> In step S106, the main processing unit 8d outputs an error notification indicating that the empty feed condition has occurred, through either or both of the display device 802 and the communication device 85.

[0150] The display device 802 and the communication device 85 are examples of information output devices.

[0151] After executing the process in step S106, the main processing unit 8d terminates the feeding control. As a result, the feeding control is stopped.

[0152] <Process S107> In step S107, the timing processing unit 8e starts the second timing process.

[0153] After executing the process in step S107, the main processing unit 8d moves the process to step S108.

[0154] Furthermore, while the processes from step S107 onward are being executed, the transport control unit 8b instructs the sheet transport device 3 to transport the target sheet 9a along the transport path 30, and the print control unit 8c instructs the print device 4 to form an image on the target sheet 9a.

[0155] <Process S108> In step S108, the state determination unit 8f selects the following process depending on whether the feeding process performed in step S103 corresponds to one or more standard feeding processes that satisfy predetermined standard feeding conditions.

[0156] The aforementioned standard feeding conditions are conditions that indicate a situation in which there is no positional deviation of the target sheet 9a relative to the initial reference position P1 at the time the feeding process is started, or where the positional deviation is assumed to be negligibly small.

[0157] The next sheet 9b may be sent out as the accompanying sheet from the initial reference position P1 in the sheet feeding direction D1 when the feeding process is executed (see Figure 3). In this case, the position of the next sheet 9b is shifted in the sheet feeding direction D1 relative to the initial reference position P1. The next sheet 9b, which has experienced a positional shift, is fed as a new target sheet 9a in the next feeding process.

[0158] When the target sheet 9a with the aforementioned misalignment is fed, the target measurement time T1a is smaller compared to when the target sheet 9a without the misalignment is fed. Figures 12 and 13 show an example in which the target measurement time T1a in the 6th feeding process is smaller than the measurement time T1 in the 5th feeding process because the misalignment of the next sheet 9b occurred in the 5th feeding process.

[0159] Furthermore, Figures 12 to 14 show examples where the positional displacement of the target sheet 9a increases as the number of feeding processes increases. As shown in Figures 12 to 14, when the number of feeding processes after the lift mechanism 21 lifts the loaded sheet 90 to the contact position is small, the positional displacement of the target sheet 9a is often not present or is small.

[0160] Furthermore, even if the lift mechanism 21 raises or lowers the loading sheet 90 under the circumstances in which the positional misalignment occurs, the positional misalignment will not be resolved.

[0161] In this embodiment, the standard feeding condition is a predetermined single feeding process or a predetermined number of feeding processes that occur after the sheet return process by the return mechanism 28 is executed and the lift mechanism 21 first lifts the loaded sheet 90 from the separation position to the contact position.

[0162] For example, the standard feeding condition is the feeding process that is performed for the first or second time after the lift mechanism 21 first lifts the loaded sheet 90 to the contact position after the sheet return process is executed. Alternatively, the standard feeding condition is the feeding process that is performed from the ith to the jth time after the lift mechanism 21 first lifts the loaded sheet 90 to the contact position after the sheet return process is executed. i and j are, for example, positive integers less than 10.

[0163] In addition, during the first feeding process when the lift mechanism 21 has lifted the loading sheet 90 to the contact position, a relatively long target measurement time T1a may be measured. Therefore, it is possible to exclude the first feeding process from the standard feeding conditions.

[0164] Therefore, under conditions where the above-mentioned standard feeding conditions are met, the likelihood of the positional misalignment of the target sheet 9a not occurring increases.

[0165] The state determination unit 8f moves the process to process S109 if the feeding process performed in process S103 is the standard feeding process. On the other hand, the state determination unit 8f moves the process to process S112 if the feeding process performed in process S103 does not correspond to one or more standard feeding processes.

[0166] The conditions under which the aforementioned sheet return process is executed will be described later.

[0167] <Process S109> In step S109, the state determination unit 8f derives a standard feeding time TFS1 based on one or more target measurement times T1a measured when the standard feeding process is executed once or more times.

[0168] For example, the state determination unit 8f derives one target measurement time T1a measured when the standard feeding process is executed once as the standard feeding time TFS1.

[0169] Alternatively, the state determination unit 8f sets a representative value of the multiple target measurement times T1a measured when the standard feeding process is executed multiple times as the standard feeding time TFS1. For example, the representative value of the multiple target measurement times T1a is the average, minimum, or median of the multiple target measurement times T1a.

[0170] Furthermore, the status determination unit 8f records the information of the set reference feeding time TFS1 in the secondary storage device 83.

[0171] The reference feeding time TFS1 is the reference value of the target measurement time T1a in the feeding process under conditions where the positional misalignment of the target sheet 9a does not occur, or the positional misalignment is assumed to be negligibly small.

[0172] The standard feeding time TFS1 is used to determine whether or not the aforementioned positional misalignment occurs in each of the sheets 9, and to derive the amount of positional misalignment.

[0173] The aforementioned positional displacement is the amount of displacement of each sheet 9 relative to the initial reference position P1 at the time the feeding process for each sheet 9 is started.

[0174] The initial value of the standard feeding time TFS1 is the default standard time. The default standard time is determined by the design feeding speed of the feeding mechanism 20 and the path length from the initial reference position P1 to the detection position P3.

[0175] One or more target measurement times T1a measured by the timing processing unit 8e when the standard feeding process is executed once or more times are examples of one or more standard measurement times. In this embodiment, one or more of the standard measurement times are used to derive the standard feeding time TFS1.

[0176] In addition, the target measurement time T1a that is the subject of processing in steps S110 and S111 described later is the time measured by the timing processing unit 8e for the target sheet 9a that is fed after one or more of the reference feeding sheets have been fed. From the time the processing of step S109 is executed until the processing of steps S110 and S111 is executed, the lift mechanism 21 holds the loaded sheet 90 in the contact position.

[0177] The state determination unit 8f executes the process in step S109 and then moves the process to step S112.

[0178] <Process S110> On the other hand, in process S110, the state determination unit 8f derives the positional deviation amount by comparing the target measurement time T1a with a preset reference feeding time TFS1.

[0179] Specifically, the state determination unit 8f derives 0 as the positional displacement amount if the target measurement time T1a is equal to or greater than the reference feeding time TFS1.

[0180] On the other hand, the state determination unit 8f derives the positional displacement amount according to the difference between the target measurement time T1a and the standard feeding time TFS1 when the target measurement time T1a is less than the standard feeding time TFS1.

[0181] More specifically, the state determination unit 8f derives the difference between the target measurement time T1a and the reference feeding time TFS1 as the positional misalignment time TG1 (see Figures 13 and 14). The positional misalignment time TG1 is the time required to feed the target sheet 9a by a distance corresponding to the amount of positional misalignment.

[0182] Furthermore, the state determination unit 8f derives the amount of positional misalignment by multiplying the positional misalignment time TG1 by the reference feeding speed. Alternatively, the positional misalignment time TG1 may be derived as the amount of positional misalignment.

[0183] The aforementioned standard feeding speed is derived by dividing the path length from the initial reference position P1 to the detection position P3 by the standard feeding time TFS1. The state determination unit 8f may also derive the standard feeding speed in advance in step S109.

[0184] A state in which the positional displacement amount is greater than 0 indicates that the positional displacement has occurred. When the positional displacement amount is 0, the positional displacement time TG1 is 0.

[0185] The state determination unit 8f executes the process in step S110 and then moves the process to step S111.

[0186] <Process S111> In step S111, the state determination unit 8f derives the target feeding time TF1 by adding the positional deviation time TG1 to the target measurement time T1a (see Figures 13-14).

[0187] The target feeding time TF1 is the time after the target measurement time T1a has been corrected by the positional deviation time TG1. The target feeding time TF1 is the time required to feed the target sheet 9a from the initial reference position P1 to the detection position P3.

[0188] The positional displacement amount and the target feeding time TF1 are examples of feeding parameters that represent the feeding state of the target sheet 9a, respectively.

[0189] The delay time TD1 is the difference between the target feeding time TF1 and the delay determination time TDS1, which will be described later (see Figures 12-14). The delay time TD1 represents the degree of feeding delay caused by the pickup roller 22 or the delivery roller 23 sliding on the upper surface of each sheet 9.

[0190] The state determination unit 8f executes the process in step S111 and then moves the process to step S112.

[0191] <Process S112> In step S112, the main processing unit 8d executes the first return control described later (see Figure 9). In the first return control, the main processing unit 8d causes the return mechanism 28 to execute the sheet return process depending on the situation.

[0192] After executing the process in step S112, the main processing unit 8d moves the process to step S113.

[0193] <Process S113> In step S113, the main processing unit 8d selects the following process depending on whether all the feeding processes corresponding to the print request have been completed.

[0194] The main processing unit 8d moves the process to step S102 if all the feeding processes corresponding to the print request have not yet been completed. In this case, in step S102, the main processing unit 8d executes a process to determine the subsequent feeding timing based on the result of the second timing process started in step S107.

[0195] On the other hand, when all the feeding processes corresponding to the print request have been completed, the main processing unit 8d moves the process to step S114.

[0196] <Process S114> In step S114, the state determination unit 8f executes a component deterioration determination process, which will be described later (see Figure 10). The component deterioration determination process determines the deterioration state of the components constituting the feeding mechanism 20 based on the results of the derivation of the feeding parameters.

[0197] After the state determination unit 8f has executed the process of step S114, the main processing unit 8d terminates the sheet feeding control.

[0198] [First return control] Next, an example of the procedure for the first return control will be described with reference to the flowchart shown in Figure 9. The first return control is performed by the main processing unit 8d.

[0199] In the following description, S201 to S203 represent identification codes for the three processes in the first return control. In the first return control, the processing of process S201 is executed first.

[0200] <Process S201> In step S201, the main processing unit 8d determines whether the first return condition is met and selects the next process according to the determination result. The first return condition includes a separation failure condition in which the positional misalignment amount derived in step S110 exceeds the separation failure determination value.

[0201] The separation failure determination value is set in accordance with the path length from the initial reference position P1 to the separation position P2. For example, the separation failure determination value is the path length from the initial reference position P1 to the separation position P2 plus a predetermined correction value. Alternatively, the path length from the initial reference position P1 to the separation position P2 may be set as the separation failure determination value.

[0202] In this embodiment, the first return condition is the logical AND of the separation failure condition and the remaining sheet condition, which is that the sheet break has not been detected by the sheet break detection device 27. The separation failure condition is an example of a positional misalignment condition related to the amount of positional misalignment.

[0203] The main processing unit 8d proceeds to process S202 if the first return condition is met. On the other hand, the main processing unit 8d terminates the first return control if the first return condition is not met.

[0204] <Process S202> In step S202, the main processing unit 8d causes the biasing adjustment mechanism 280 to perform the counter-biasing operation, the lift mechanism 21 to perform the lift plate lowering operation, and the return mechanism 28 to perform the sheet return process.

[0205] In this embodiment, the process of causing the return mechanism 28 to perform the seat return process is the process of rotating the retractor member 281 by operating the drive mechanism 282.

[0206] As a result of the execution of process S202, the accompanying sheet that has reached the separation position P2 is returned to the initial reference position P1 or a position close to the initial reference position P1.

[0207] When the sheet return process is executed, the main processing unit 8d may rotate the pickup roller 22 and the feed roller 23 in the opposite direction to the rotation direction when the feeding process is executed.

[0208] The main processing unit 8d executes the process of step S202, and then executes the process of step S203.

[0209] <Process S203> In step S203, the main processing unit 8d causes the return mechanism 28 to stop the sheet return process, the biasing adjustment mechanism 280 to perform the biasing operation, and the lift mechanism 21 to perform the lift plate raising operation.

[0210] After executing the process of step S203, the main processing unit 8d terminates the first return control.

[0211] [Component degradation detection process] Next, an example of the procedure for the component degradation determination process will be described with reference to the flowchart shown in Figure 10. The component degradation determination process is performed by the state determination unit 8f.

[0212] The procedure for determining component deterioration is an example of a procedure for implementing the sheet feeding state determination method. The CPU 81, which includes the state determination unit 8f, is an example of the processing unit that implements the sheet feeding state determination method.

[0213] In the following description, S301, S302, ... represent identification codes for multiple steps in the component degradation determination process. In the component degradation determination process, the process of step S301 is executed first.

[0214] <Process S301> In step S301, the state determination unit 8f determines the delay state of feeding the target sheet 9a by comparing the target feeding time TF1 obtained in step S206 or step S207 with a preset delay determination time TDS1 (see Figures 12 and 13).

[0215] The delay determination time TDS1 is shorter than the aforementioned upper limit time.

[0216] The state determination unit 8f counts the number of delays, which is the number of times a delay state occurs, when the target feeding time TF1 exceeds the delay determination time TDS1. The delay count is the number of times when the target feeding time TF1 exceeds the delay determination time TDS1.

[0217] In step S301, the state determination unit 8f may count a plurality of individual delay counts, each of which is the number of delays.

[0218] The aforementioned number of individual delays is the number of times the target feed time TF1 exceeds each of the individual delay determination times. Each of the aforementioned individual determination times is an example of a delay determination time TDS1, and is a time that is equal to or greater than the reference feed time TFS1. As a result, the delay state of each feed in Sheet 9 is divided into multiple delay levels according to the aforementioned individual delay determination times, and the number of individual delays corresponding to each of the aforementioned delay levels is counted.

[0219] Furthermore, the multiple individual delay determination times are shorter than the upper limit time.

[0220] In step S301, the state determination unit 8f may count the first delay count and the second delay count.

[0221] The first delay count is the number of times when the amount of positional deviation does not exceed the positional deviation judgment value, and the target measurement time T1a exceeds the delay judgment time TDS1. The second delay count is the number of times when the amount of positional deviation exceeds the positional deviation judgment value, and the target measurement time T1a exceeds the delay judgment time TDS1.

[0222] The state determination unit 8f executes the process in step S301 and then moves the process to step S302.

[0223] <Process S302> In step S302, the state determination unit 8f determines the positional displacement state of the target sheet 9a by comparing the positional displacement amount derived in step S111 with the positional displacement determination value and the separation failure determination value.

[0224] The positional misalignment determination value is smaller than the separation failure determination value.

[0225] Specifically, the state determination unit 8f counts the number of separation failures when the amount of positional misalignment exceeds the separation failure determination value. The number of separation failures is the number of times when the amount of positional misalignment exceeds the separation failure determination value.

[0226] If the amount of misalignment exceeds the separation failure determination value, it is considered that a separation failure has occurred in the target sheet 9a. The separation failure is a state in which the leading edge of the target sheet 9a has reached the separation position P2 or a position downstream of the separation position P2 in the sheet feeding direction D1 at the start of the feeding process.

[0227] In step S302, the state determination unit 8f may count a plurality of individual separation failure counts, each of which is the number of separation failures.

[0228] The number of times each of the multiple individual separation failures occurs is the number of times the positional displacement exceeds each of the multiple individual separation failure judgment values. Each of the multiple individual separation failure judgment values ​​is an example of the separation failure judgment value. As a result, the separation failure state of each sheet 9 is divided into multiple separation failure degrees according to the multiple individual separation failure judgment values, and the number of times each of the multiple individual separation failures that corresponds to each of the multiple separation failure degrees is counted.

[0229] In step S302, the state determination unit 8f may derive a positional misalignment excess amount, which represents the amount by which the positional misalignment exceeds the separation failure determination value. Specifically, the positional misalignment excess amount is the difference between the positional misalignment amount and the separation failure determination value.

[0230] Furthermore, the state determination unit 8f counts the number of misalignments if the amount of misalignment does not exceed the separation failure determination value and exceeds the misalignment determination value. On the other hand, the state determination unit 8f counts the number of non-misalignments if the amount of misalignment does not exceed the misalignment determination value.

[0231] The number of misaligned positions is an example of the number of times the amount of misalignment exceeds the misalignment determination value. The number of non-misaligned positions is the number of times the amount of misalignment does not exceed the misalignment determination value.

[0232] The positional misalignment state for which the number of positional misalignments is counted is the state in which the leading edge of the target sheet 9a at the start of the feeding process has reached a predetermined range between the initial reference position P1 and the separation position P2.

[0233] The state determination unit 8f executes the process in step S302 and then moves the process to step S303.

[0234] <Process S303> In step S303, the state determination unit 8f counts the number of feeding operations, which is the number of feeding operations.

[0235] The state determination unit 8f executes the process in step S303 and then moves the process to step S304.

[0236] <Process S304> In step S304, the state determination unit 8f records feed performance data, which includes information on the actual feed conditions of various feed states obtained in steps S301 to S303, in the secondary storage device 83.

[0237] Specifically, the status determination unit 8f records the feeding performance data, including information on the number of feeding cycles, the number of delays, and the number of separation failures, in the secondary storage device 83.

[0238] The status determination unit 8f may further record the feed and transfer performance data, including information on the number of individual delays, in the secondary storage device 83.

[0239] The status determination unit 8f may further record the feeding performance data, including information on the first delay count and the second delay count, in the secondary storage device 83.

[0240] The state determination unit 8f may further record the feeding performance data, including information on the number of positional deviations and the number of non-positional deviations, in the secondary storage device 83.

[0241] The status determination unit 8f may further record the feeding performance data, including information on the number of times each individual separation failed, in the secondary storage device 83.

[0242] The state determination unit 8f may further record the feeding performance data, including information on the excess positional deviation, in the secondary storage device 83. In this case, the feeding performance data is an example of the actual data on the excess positional deviation.

[0243] The state determination unit 8f executes the process in step S304 and then moves the process to step S305.

[0244] <Process S305> In step S305, the state determination unit 8f performs a deterioration determination of the supplied parts based on the supply performance data.

[0245] In this embodiment, the feeding components are a pickup roller 22 and a delivery roller 23. In the following description, the state in which the degree of deterioration of the feeding components is determined to be outside the acceptable range is referred to as the feeding component deterioration state. The degree of deterioration of the feeding components is an example of the determination result of the deterioration state of the feeding mechanism 20.

[0246] For example, the state determination unit 8f determines that the supply component deterioration state has occurred when the number of delays exceeds a preset delay threshold.

[0247] Furthermore, a plurality of individual delay count thresholds corresponding to each of the plurality of individual delay counts may be set in advance. In this case, the state determination unit 8f determines that the supply component deterioration state has occurred when each of the plurality of individual delay counts exceeds each of the plurality of individual delay count thresholds.

[0248] Furthermore, the state determination unit 8f may determine that the feeding component deterioration state has occurred when the first delay count exceeds a preset first delay count threshold. Similarly, the state determination unit 8f may determine that the feeding component deterioration state has occurred when the second delay count exceeds a preset second delay count threshold.

[0249] Furthermore, the state determination unit 8f may determine that the feeding component deterioration state has occurred when the frequency of the first delay count relative to the number of non-positional misalignment counts exceeds a preset first delay frequency threshold. Similarly, the state determination unit 8f may determine that the feeding component deterioration state has occurred when the frequency of the second delay count relative to the number of positional misalignment counts exceeds a preset second delay frequency threshold.

[0250] By using the first and second delay counts in the degradation determination, it becomes possible to perform a detailed degradation determination that reflects the difference in the relationship between the frequency of feed delays and component degradation, depending on the magnitude of the positional deviation.

[0251] The state determination unit 8f determines that the degree of deterioration of the feeding component is outside the acceptable range, and proceeds to process S306. On the other hand, the state determination unit 8f determines that the degree of deterioration of the feeding component is not outside the acceptable range, and proceeds to process S307.

[0252] <Process S306> In step S306, the status determination unit 8f outputs a feed component deterioration alarm through either or both of the display device 802 and the communication device 85. The feed component deterioration alarm is an alarm that prompts maintenance or replacement of the feed component.

[0253] For example, the status determination unit 8f displays the information about the feed component deterioration alarm on the display device 802. Alternatively, the status determination unit 8f may transmit the information about the feed component deterioration alarm to the administrator's terminal via the communication device 85.

[0254] The state determination unit 8f executes the process in step S306 and then moves the process to step S307.

[0255] <Process S307> In step S307, the state determination unit 8f performs a deterioration determination of the separated parts based on the feeding performance data.

[0256] In this embodiment, the separation component is a retard roller 24. In the following description, the state in which the degree of deterioration of the separation component is determined to be outside the acceptable range is referred to as the deterioration state of the separation component. The degree of deterioration of the separation component is an example of the determination result of the deterioration state of the feeding mechanism 20.

[0257] For example, the state determination unit 8f determines that the separated component has deteriorated if the number of separation failures exceeds a preset threshold for the number of separation failures.

[0258] Furthermore, the state determination unit 8f may determine that the separated component is degraded if the frequency of the number of separation failures relative to the number of feeding cycles exceeds the first frequency threshold.

[0259] Furthermore, the state determination unit 8f may determine that the separated component has deteriorated if the frequency of the number of separation failures relative to the number of positional misalignments exceeds the second frequency threshold.

[0260] Furthermore, the state determination unit 8f may determine that the feeding component deterioration state has occurred when the representative value of the actual value of the excess positional deviation exceeds the excess threshold. For example, the representative value of the actual value of the excess positional deviation is the maximum or average value of the actual value of the excess positional deviation.

[0261] Furthermore, multiple threshold values ​​for the number of individual separation failures, each corresponding to one of the multiple individual separation failure counts, may be set in advance. In this case, the state determination unit 8f determines that the separated component deterioration state has occurred when each of the multiple individual separation failure counts exceeds each of the multiple individual separation failure count threshold values.

[0262] The state determination unit 8f proceeds to process S308 if it determines that the degree of deterioration of the separated part is outside the acceptable range. On the other hand, the state determination unit 8f terminates the part deterioration determination process if it determines that the degree of deterioration of the separated part is not outside the acceptable range.

[0263] <Process S308> In step S308, the status determination unit 8f outputs a separated component deterioration alarm through either or both of the display device 802 and the communication device 85. The separated component deterioration alarm is an alarm that prompts maintenance or replacement of the separated component.

[0264] For example, the status determination unit 8f displays the information about the separated component deterioration alarm on the display device 802. Alternatively, the status determination unit 8f may transmit the information about the separated component deterioration alarm to the administrator's terminal via the communication device 85.

[0265] By executing processes S108 to S111 and process S301, it is possible to determine the delay state of feeding each sheet 9 without requiring the addition of equipment. Furthermore, by executing the component deterioration determination process, it is possible to determine the deterioration state of the feeding components and the separation components in the sheet feeding device 2.

[0266] As described above, the return mechanism 28 realizes the function of ensuring that the initial position of each sheet 9 is not misaligned. Furthermore, the sheet feeding device 2 realizes the function of obtaining the target measurement time T1a for the next target sheet 9a after ensuring that the target sheet 9a is not misaligned from the initial reference position P1 by the first return control. As a result, it is possible to accurately determine the feeding status of each sheet 9.

[0267] The first return control is executed while the sheet feeding control is being performed (see Figure 8). On the other hand, the main processing unit 8d executes the second return control when the sheet feeding control is not being performed.

[0268] [Second return control] Below, an example of the procedure for the second return control will be described with reference to the flowchart shown in Figure 11.

[0269] In the following description, S401 to S403 represent identification codes for the three processes in the second return control. In the second return control, the process of process S401 is executed first.

[0270] <Step S401> In step S401, the main processing unit 8d determines whether the second return condition is satisfied, and selects the next process according to the determination result. The second return condition includes one or both of the feeding frequency condition and the instruction input condition.

[0271] The feeding frequency condition is a condition that the number of times the feeding process is executed reaches a preset target number of times. For example, the main processing unit 8d determines whether the feeding frequency condition is satisfied when the image forming apparatus 10 is started and when the sheet feeding control ends.

[0272] The instruction input condition is a condition that an instruction to execute the sheet return process is input. For example, the instruction to execute the sheet return process is input through the operation device 801 or the communication device 85.

[0273] In the present embodiment, the second return condition is a logical sum condition of the feeding frequency condition and the instruction input condition. Note that the second return condition may include a condition that the number of times the positional deviation amount exceeds the separation failure determination value exceeds the separation failure number threshold. This condition is also an example of the positional deviation condition regarding the positional deviation amount.

[0274] When the second return condition is satisfied, the main processing unit 8d transfers the process to step S402. On the other hand, when the second return condition is not satisfied, the main processing unit 8d repeats the process of step S401.

[0275] <Step S402> In step S402, the main processing unit 8d causes the biasing adjustment mechanism 280 to execute the anti-biasing operation, causes the lift mechanism 21 to execute the lift plate lowering operation, and further causes the return mechanism 28 to execute the sheet return process.

[0276] The process of step S402 is the same as the process of step S202 (see FIG. 9). 1]

[0277] As a result of the execution of process S402, the accompanying sheet that has reached the separation position P2 is returned to the initial reference position P1 or a position close to the initial reference position P1.

[0278] The main processing unit 8d executes the process of step S402, and then executes the process of step S403.

[0279] <Process S403> In step S403, the main processing unit 8d causes the return mechanism 28 to stop the sheet return process, the biasing adjustment mechanism 280 to perform the biasing operation, and the lift mechanism 21 to perform the lift plate raising operation.

[0280] The process in step S403 is the same as the process in step S203 (see Figure 9).

[0281] After executing the process in step S403, the main processing unit 8d moves the process to step S401.

[0282] By executing the second return control, the sheet feeding device 2 can measure the target measurement time T1a while ensuring that the initial position of the target sheet 9a is not shifted. As a result, it is possible to accurately determine the feeding status of each sheet 9.

[0283] [First variation] Next, with reference to Figure 15, an image forming apparatus 10A according to the first modified example will be described. The image forming apparatus 10A has a configuration in which the sheet feeding device 2A of the image forming apparatus 10 is replaced with a sheet feeding device 2A. The following describes the parts of the sheet feeding device 2A that differ from the sheet feeding device 2.

[0284] The sheet feeding device 2A has a configuration in which the repulsion member 281 and the drive mechanism 282 are removed from the sheet feeding device 2. In the sheet feeding device 2A, the feeding mechanism 20 also serves as the return mechanism 28.

[0285] The sheet return process by the feeding mechanism 20 is a process in which the pickup roller 22 and the delivery roller 23 are rotated by a predetermined amount in the opposite direction of rotation when the feeding process is performed, before the lift mechanism 21 switches from the contact state to the separation state.

[0286] The feeding mechanism 20 returns the misaligned sheet to the upstream side in the sheet feeding direction D1 by executing the sheet return process.

[0287] When the sheet return process is performed by the feeding mechanism 20, the main processing unit 8d causes the biasing adjustment mechanism 280 to perform the counter-biasing operation.

[0288] When the sheet feeding device 2A is used, in the first return control step S202 and the second return control step S402, the main processing unit 8d performs the following processing.

[0289] Specifically, the main processing unit 8d causes the biasing adjustment mechanism 280 to perform the counter-biasing operation, the feeding mechanism 20 to perform the sheet return operation, and the lift mechanism 21 to perform the lift plate lowering operation.

[0290] When the sheet feeding device 2A is used, in the first return control step S203 and the second return control step S403, the main processing unit 8d performs the following processing.

[0291] In other words, the main processing unit 8d causes the feeding mechanism 20 to stop the sheet return process, the biasing adjustment mechanism 280 to perform the biasing operation, and the lift mechanism 21 to perform the lift plate raising operation.

[0292] The same effects can be obtained when sheet feeding device 2A is used as when sheet feeding device 2 is used.

[0293] [Second variation] Next, while referring to FIG. 16, the image forming apparatus 10B according to the second modification example will be described. The image forming apparatus 10B has a configuration in which the control device 8 of the image forming apparatus 10 is replaced with a control device 8B. Hereinafter, differences between the control device 8B and the control device 8 will be described.

[0294] The control device 8B has a configuration in which a remaining amount detection unit 8g is added to the paper feed control unit 8a of the control device 8. That is, the paper feed control unit 8a, which is one of the plurality of processing modules, includes the remaining amount detection unit 8g.

[0295] The remaining amount detection unit 8g detects the remaining amount of sheets. The CPU 81 including the remaining amount detection unit 8g is an example of a remaining amount detection device.

[0296] For example, the remaining amount detection unit 8g measures the initial rising time from the time when the lift mechanism 21 starts the lift plate rising operation from the state where the lift plate 211 is at the lower end position until the contact state is switched.

[0297] Furthermore, the remaining amount detection unit 8g derives the initial sheet remaining amount by applying the initial rising time to a predetermined conversion formula. The initial sheet remaining amount is larger as the initial rising time is shorter.

[0298] Furthermore, the remaining amount detection unit 8g derives the sheet remaining amount by subtracting a unit amount from the initial sheet remaining amount each time the paper feed process is executed.

[0299] Note that the sheet feeding device 2 may include a rotary encoder that detects the rotation angle of the rotation shaft 211a of the lift plate 211 or the rotation shaft 212a of the push-up plate 212. In this case, the detection angle of the rotary encoder when the lift mechanism 21 maintains the contact state represents the remaining amount of sheets. The rotary encoder is an example of a remaining amount detection device.

[0300] In this modified example, one or both of the first return condition in the first return control and the second return condition in the second return control include the sheet remaining amount condition shown below.

[0301] The aforementioned sheet remaining amount condition is that the remaining amount of the sheet detected by the remaining amount detection unit 8g falls into one of a set number of remaining amount categories.

[0302] In the sheet feeding device 2, the sheet feeding characteristics may differ depending on the remaining sheet quantity. Differences in sheet feeding characteristics affect the standard feeding time TFS1.

[0303] As described above, in the first return control or the second return control, each time the first return condition or the second return condition is met, the main processing unit 8d causes the return mechanism 28 to execute the sheet return process (see steps S201 to S202, or steps S401 to S402).

[0304] That is, in the first return control or the second return control in this modified example, the main processing unit 8d causes the return mechanism 28 to execute the sheet return process each time the sheet remaining amount condition is met.

[0305] Furthermore, each time the sheet return process is executed, the standard feeding conditions are met in step S108 of the sheet feeding control, and the standard feeding time TFS1 is set in step S109.

[0306] Therefore, by adopting the sheet remaining amount condition, an appropriate standard feeding time TFS1 is set according to each of the multiple remaining amount categories.

[0307] [Third variation] Next, we will describe the sheet feeding device 2 in the image forming apparatus according to the third modified example.

[0308] In this modified example, the feeding mechanism 20 further includes a pickup roller displacement mechanism. The pickup roller displacement mechanism moves the pickup roller 22 between an operating position in contact with the upper surface of the topmost sheet on the loading sheet 90 and a retracted position spaced upward from the topmost sheet.

[0309] The pickup roller displacement mechanism is an example of a displacement mechanism for displacing the pickup roller 22. The pickup roller displacement mechanism can switch between a contact state in which the loading sheet 90 and the pickup roller 22 are in contact and a separation state in which the loading sheet 90 and the pickup roller 22 are separated by displacing the pickup roller 22.

[0310] In the following description, the operation by which the pickup roller displacement mechanism moves the pickup roller 22 from the operating position to the retracted position will be referred to as the retraction operation. Similarly, the operation by which the pickup roller displacement mechanism moves the pickup roller 22 from the retracted position to the operating position will be referred to as the feeding preparation operation.

[0311] In the modified example, in the first return control step S202 and the second return control step S402, the main processing unit 8d performs the following first alternative process instead of causing the lift mechanism 21 to perform the lift plate lowering operation.

[0312] The first alternative process is a process that causes the pickup roller displacement mechanism to perform the retraction operation.

[0313] In the modified example, in steps S203 and S403 of the second return control, the main processing unit 8d performs the following second alternative processing instead of causing the lift mechanism 21 to perform the lift plate raising operation.

[0314] The second alternative process is a process that causes the pickup roller displacement mechanism to perform the feeding preparation operation.

[0315] Even when this modified version is adopted, the same effects as when sheet feeding device 2 or sheet feeding device 2A is adopted can be obtained.

[0316] [Fourth variation] Next, we will describe the sheet feeding device 2 in the image forming apparatus according to the fourth modified example.

[0317] As described above, in the second return control, the sheet return process is executed each time the feeding count condition is met (see steps S401 and S402).

[0318] Furthermore, each time the sheet return process is executed, the standard feeding conditions are met in step S108 of the sheet feeding control, and the standard feeding time TFS1 is set in step S109.

[0319] In this modified example, the state determination unit 8f derives a reference delay time representing the degree of delay in the reference feeding process each time the reference feeding time TFS1 is set in process S109. The reference delay time represents the degree of delay in the reference feeding process.

[0320] The state determination unit 8f derives the reference delay time based on the reference feeding time TFS1 and the preset delay determination time TDS1.

[0321] Specifically, the state determination unit 8f derives the difference between the reference feeding time TFS1 and the delay determination time TDS1 as the reference delay time when the reference feeding time TFS1 exceeds the delay determination time TDS1.

[0322] On the other hand, the state determination unit 8f sets the reference delay time to 0 if the reference feeding time TFS1 does not exceed the delay determination time TDS1.

[0323] Furthermore, in step S109, the main processing unit 8d changes the target number of feeding cycles condition based on either the magnitude of the reference delay time or the change in the reference delay time, or both.

[0324] For example, the main processing unit 8d executes either or both of the first target count change process and the second target count change process.

[0325] The first target count change process is a process that changes the target count to a smaller number of times when the reference delay time exceeds the delay threshold, or when the number of times the reference delay time exceeds the delay threshold exceeds a specific number of times.

[0326] The second target count modification process is a process that changes the target count to a smaller number of times when the amount of change in the reference delay time exceeds the change threshold.

[0327] The delay threshold, the specific number of occurrences, and the change threshold are each set in advance.

[0328] When the reference delay time exceeds the delay threshold, and when the amount of change in the reference delay time exceeds the amount of change threshold, it is highly likely that the reference feeding time TFS1 will change at a rapid pace due to the progression of deterioration of the pickup roller 22 or the feed roller 23.

[0329] When this modified configuration is adopted, the sheet return process and the setting of the standard feed time TFS1 are performed relatively frequently in situations where the standard feed time TFS1 is likely to change at a rapid pace. This allows for the rapid setting of an appropriate standard feed time TFS1 according to the deterioration state of the pickup roller 22 and the delivery roller 23.

[0330] Furthermore, the main processing unit 8d may set a smaller target number of times as the total cumulative number of feeding operations increases.

[0331] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0332] <Note 1> A feeding mechanism comprising a feeding rotating body that contacts the upper surface of the top sheet in a loading sheet, a discharge rotating body positioned at a distance from the feeding rotating body, and a separating member positioned below the discharge rotating body and biased toward the discharge rotating body, wherein a feeding process is performed to feed each sheet from the loading sheet to a transport path by rotating the feeding rotating body and the discharge rotating body, and the separating member separates the accompanying sheets that are discharged together with each sheet from each sheet, A displacement mechanism that can switch between a contact state in which the loading sheet and the feeding rotating body are in contact and a separation state in which the loading sheet and the feeding rotating body are separated by displacing the loading sheet or the feeding rotating body, A sheet detection device that detects each of the sheets at a position downstream of the sheet feeding direction relative to the feed rotating body and the separating member, A timing device that measures the elapsed time from the time when the feeding process for each of the sheets is started until the time when each of the sheets is detected by the sheet detection device, A return mechanism is provided that, when the displacement mechanism switches from the contact state to the separation state, performs a sheet return process to return the misaligned sheet, which has shifted downstream in the sheet feeding direction relative to the initial reference position, to the upstream side in the sheet feeding direction. A processing device that derives a positional deviation amount, which represents the amount of deviation of the target sheet's position from the initial reference position at the time the feeding process for the target sheet begins, based on a pre-set reference feeding time and a target measurement time measured by the timing device for the target sheet being fed by the feeding process, A sheet feeding device comprising a control device that causes the return mechanism to execute the sheet return process when the amount of positional misalignment satisfies predetermined positional misalignment conditions.

[0333] <Note 2> The feeding mechanism includes a sheet break detection device that detects when there are no sheets remaining that can be fed, The sheet feeding device according to Appendix 1, wherein the control device causes the return mechanism to perform the sheet return process when the amount of misalignment satisfies the misalignment condition and the sheet break has not been detected by the sheet break detection device.

[0334] <Note 3> The sheet feeding device according to Appendix 2, wherein the positional displacement condition includes the condition that the amount of positional displacement exceeds a separation failure determination value corresponding to the path length from the initial reference position to the position of the separation member.

[0335] <Note 4> The sheet feeding device according to any one of the appendices 1 to 3, wherein the processing device sets the standard feeding time based on one or more standard feeding processes that satisfy the standard feeding condition, which is one or more feeding processes that are performed a predetermined number of times after the displacement mechanism first switches from the separated state to the contact state after the sheet return process is performed, measured by the timing device.

[0336] <Note 5> Equipped with a remaining amount detection device that detects the remaining amount of sheets, The sheet feeding device according to Appendix 4, wherein the control device causes the return mechanism to perform the sheet return process each time the detected remaining sheet amount falls into one of a plurality of preset remaining amount categories.

[0337] <Note 6> The sheet feeding device according to Appendix 4 or Appendix 5, wherein the control device causes the return mechanism to perform the sheet return process each time the number of times the feeding process has been performed reaches a preset target number.

[0338] <Note 7> The processing device, each time the standard feeding time is set, derives a standard delay time representing the degree of delay in the standard feeding process based on the standard feeding time and a predetermined delay determination time. The sheet feeding device according to Appendix 6, wherein the control device changes the target number of times based on the magnitude of the reference delay time and / or the change in the reference delay time.

[0339] <Note 8> The sheet feeding device according to any one of the appendices 1 to 7, wherein the return mechanism includes a bias adjustment mechanism for easing the biasing of the separating member toward the feeding rotating body or releasing the biasing of the separating member toward the feeding rotating body when the sheet return process is performed.

[0340] <Note 9> The aforementioned return mechanism is A retraction member is supported so as to be rotatable around a shaft portion positioned above or below the pre-separation path, which is the path from the initial reference position to the position of the separation member, It has a drive mechanism for rotating the aforementioned repulsive member, A sheet feeding device according to any one of the appendices 1 to 8, wherein the rotating repelling member repels the misaligned sheet toward the upstream side in the sheet feeding direction, thereby returning the misaligned sheet to the upstream side in the sheet feeding direction.

[0341] <Note 10> The feeding mechanism also serves as the return mechanism. The sheet feeding device according to any one of the appendices 1 to 8, wherein the feeding mechanism returns the misaligned sheet to the upstream side in the sheet feeding direction by rotating the feeding rotating body by a predetermined amount in the opposite direction of rotation when the feeding process is performed, before the displacement mechanism switches from the contact state to the separation state.

[0342] <Note 11> The sheet feeding device according to any one of the appendices 1 to 10, wherein the displacement mechanism is a lift mechanism that switches between the contact state and the separation state by raising and lowering the loaded sheet.

[0343] <Note 12> A sheet feeding device described in any one of the above appendices 1 to 11, An image forming apparatus comprising: a printing device that forms an image on each sheet fed by the aforementioned sheet feeding device. [Explanation of symbols]

[0344] 2,2A: Sheet feeding device 4: Printing device 8: Control device 9a: Target sheet 10: Image forming apparatus 20: Feeding mechanism 21: Lift mechanism 22: Pickup Roller 23: Feed Roller 24: Retard Roller 25: Feeding sheet detection device 27: Sheet break detection device 28: Return mechanism 28a:Shaft part 30: Conveyor path 200: Sheet Cassette 200a: Cassette tip wall 211: Lift plate 211b :Aperture 212: Push-up board 230: Feed motor 240: Retard Unit 271: Oscillating member 271a:Shaft part 271b: Arm section 271c: Detected part 272: Object detection sensor 280: Force adjustment mechanism 281: Repelling component

Claims

1. A feeding mechanism comprising a feeding rotating body that contacts the upper surface of the top sheet in a loading sheet, a discharge rotating body positioned at a distance from the feeding rotating body, and a separating member positioned below the discharge rotating body and biased toward the discharge rotating body, wherein a feeding process is performed to feed each sheet from the loading sheet to a transport path by rotating the feeding rotating body and the discharge rotating body, and the separating member separates the accompanying sheets that are discharged together with each sheet from each sheet, A displacement mechanism that can switch between a contact state in which the loading sheet and the feeding rotating body are in contact and a separation state in which the loading sheet and the feeding rotating body are separated by displacing the loading sheet or the feeding rotating body, A sheet detection device that detects each of the sheets at a position downstream of the sheet feeding direction relative to the feed rotating body and the separating member, A timing device that measures the elapsed time from the time when the feeding process for each of the sheets is started until the time when each of the sheets is detected by the sheet detection device, A return mechanism is provided that, when the displacement mechanism switches from the contact state to the separation state, performs a sheet return process to return the misaligned sheet, which has shifted downstream in the sheet feeding direction relative to the initial reference position, to the upstream side in the sheet feeding direction. A processing device that derives a positional deviation amount, which represents the amount of deviation of the target sheet's position from the initial reference position at the time the feeding process for the target sheet begins, based on a pre-set reference feeding time and a target measurement time measured by the timing device for the target sheet being fed by the feeding process, A sheet feeding device comprising a control device that causes the return mechanism to execute the sheet return process when the amount of positional misalignment satisfies predetermined positional misalignment conditions.

2. The feeding mechanism includes a sheet break detection device that detects when there are no sheets remaining that can be fed, The sheet feeding device according to claim 1, wherein the control device causes the return mechanism to perform the sheet return process when the amount of misalignment satisfies the misalignment condition and the sheet break has not been detected by the sheet break detection device.

3. The sheet feeding device according to claim 2, wherein the positional displacement condition includes the condition that the amount of positional displacement exceeds a separation failure determination value corresponding to the path length from the initial reference position to the position of the separation member.

4. The sheet feeding device according to any one of claims 1 to 3, wherein the processing device sets the standard feeding time based on one or more standard feeding processes that satisfy the standard feeding condition, which is one or more feeding processes that are executed a predetermined number of times after the displacement mechanism first switches from the separated state to the contact state after the sheet return process is executed, measured by the timing device.

5. Equipped with a remaining amount detection device that detects the remaining amount of sheets, The sheet feeding device according to claim 4, wherein the control device causes the return mechanism to perform the sheet return process each time the detected remaining sheet amount falls into one of a plurality of preset remaining amount categories.

6. The sheet feeding device according to claim 4, wherein the control device causes the return mechanism to perform the sheet return process each time the number of times the feeding process has been performed reaches a preset target number.

7. The processing device, each time the standard feeding time is set, derives a standard delay time representing the degree of delay in the standard feeding process based on the standard feeding time and a predetermined delay determination time. The sheet feeding device according to claim 6, wherein the control device changes the target number of times based on the magnitude of the reference delay time and / or the change in the reference delay time.

8. The sheet feeding device according to any one of claims 1 to 3, wherein the return mechanism includes a bias adjustment mechanism for easing the biasing of the separating member toward the feeding rotating body or releasing the biasing of the separating member toward the feeding rotating body when the sheet return process is performed.

9. The aforementioned return mechanism is A retraction member is supported so as to be rotatable around a shaft portion positioned above or below the pre-separation path, which is the path from the initial reference position to the position of the separation member, It has a drive mechanism for rotating the aforementioned repulsive member, The sheet feeding device according to any one of claims 1 to 3, wherein the rotating repelling member repels the misaligned sheet toward the upstream side in the sheet feeding direction, thereby returning the misaligned sheet to the upstream side in the sheet feeding direction.

10. The feeding mechanism also serves as the return mechanism. The sheet feeding device according to any one of claims 1 to 3, wherein the feeding mechanism returns the misaligned sheet to the upstream side in the sheet feeding direction by rotating the feeding rotating body by a predetermined amount in the opposite direction of rotation when the feeding process is performed, before the displacement mechanism switches from the contact state to the separation state.

11. The sheet feeding device according to any one of claims 1 to 3, wherein the displacement mechanism is a lift mechanism that switches between the contact state and the separation state by raising and lowering the loaded sheet.

12. A sheet feeding device according to any one of claims 1 to 3, An image forming apparatus comprising: a printing device that forms an image on each sheet fed by the aforementioned sheet feeding device.

Images