Sheet feeding device and image forming apparatus

Abstract

To automatically detect that a feeding roller is replaced with a new one.SOLUTION: A sheet feeding device includes: a stacking plate 52 on which sheets S are stacked and capable of moving up and down; a pickup roller 21 that feeds the sheets S; a roller holder 23 that supports the pickup roller 21; a feeding roller unit 20 having a detection flag 24 provided on the roller holder 23; a feeding roller holding unit 30 having a sheet surface sensor 32 for detecting the detection flag 24, arranged above the stacking plate 52, and detachably holding the feeding roller unit 20; and a control unit 80 that controls a lift-up drive unit 70 to raise the stacking plate 52 and sets a state in which the sheet S can be fed based on a detection result of the sheet surface sensor 32, in which when the feeding roller unit 20 is attached, the control unit 80 controls the lift-up drive unit 70 to move the stacking plate 52 up and down, and based on the detection result of the paper surface sensor 32, determines whether or not the feeding roller unit 20 is new.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device and an image forming apparatus equipped with the sheet feeding device. [Background technology]

[0002] Conventionally, image forming devices such as copiers and printers have been equipped with a feed mechanism that separates and feeds sheets of recording material loaded in a paper feed section one by one, and a transport mechanism that transports the sheets to the image forming section. For example, feed mechanisms typically use rubber rollers to feed the sheets one by one. The feed rollers are made of soft, easily worn rubber to transport various types of media. Therefore, repeated paper transport can cause significant wear on the surface of the feed roller. Furthermore, various factors, such as the adhesion of paper dust to the feed roller and deterioration of the rubber, can degrade the feed roller's paper transport performance. In recent years, image forming device bodies have been designed to have longer lifespans. Feed rollers, which are prone to wear and deterioration, are designed to be easily replaceable, thereby addressing the need for replacement and extending the lifespan of image forming device bodies.

[0003] Replaceable feed rollers are considered consumables and are replaced with new ones by users or service personnel. Various detection methods have been proposed for an image forming apparatus to detect when to replace the feed roller. For example, in Patent Document 1, the time from when the feed roller starts to rotate until a sheet is transported to a sensor located downstream of the transport path is measured, and a delay in the transport of the sheet is detected based on the measured time. When the detected rate of sheet transport delay exceeds a threshold, the image forming apparatus notifies the user or service personnel that the feed roller needs to be replaced. Furthermore, when the image forming apparatus determines that the feed roller needs to be replaced, it prompts the user or service personnel to replace the feed roller to prevent transport problems.

[0004] When a user or a service technician replaces the feed roller, the image forming device must detect that the feed roller has been replaced with a new one and stop the notification operation that prompts the user to replace the feed roller. Therefore, the user or service technician must perform a reset operation or the like via an operation panel or the like of the image forming device to indicate that the replacement of the feed roller has been completed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-007758 Summary of the Invention [Problem to be solved by the invention]

[0006] The reset operation described above is an operation performed by an operator (worker) such as a user or a service technician. Therefore, it is conceivable that the operator may forget to perform the reset operation to indicate completion of the feed roller replacement or to check the operation after replacing the feed roller with a new one. In such a case, because the reset operation has not been performed, the image forming apparatus will determine that the feed roller needs to be replaced and will continue to notify the user or service technician that the feed roller needs to be replaced.

[0007] In addition, in an image forming apparatus with multiple paper feed inlets, it is possible that an operator may mistakenly perform a reset operation to set the completion of replacement of a feed roller of a paper feed inlet that has not been replaced. As a result, the image forming apparatus may not be able to correctly detect the actual usage status of the feed roller. Therefore, it is desirable for the image forming apparatus to be able to automatically and correctly detect that a feed roller has been replaced with a new one without human intervention, without relying on a reset operation by a user or service technician.

[0008] The present invention has been made under such circumstances, and an object of the present invention is to automatically detect when the feeding roller has been replaced with a new one. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0010] (1) A feeding unit including a loading section having a loading plate on which sheets are loaded and which can be raised and lowered, a feeding roller for feeding the sheets, a rotatable support section for supporting the feeding roller, and a detectable member provided on the support section, a holding unit having a detection means for detecting the detectable member and disposed above the loading section, and for detachably holding the feeding unit, a drive section for raising and lowering the loading plate, and control means for controlling the drive section to rotate the loading plate to raise it and for setting the sheets loaded on the loading plate to a state where they can be fed based on the detection result of the detectable member by the detection means, The detectable member is located at a first position where it cannot be detected by the detection means when the feeding unit is new, and when a new feeding unit is attached to the holding unit and the feeding roller is driven, it moves from the first position to a second position where the detectable member protrudes so that it can be detected by the detection means, and when the feeding unit is attached, the control means controls the drive unit to raise and lower the loading plate so that the sheet on the loading plate is set in a state where it can be fed, and determines whether the feeding unit is new based on the detection result of the detection means.

[0011] (2) A feeding unit having a loading section having a loading plate on which sheets are loaded, a feeding roller for feeding the sheets, a rotatable support section supporting the feeding roller, and a detectable member provided on the support section; a detection means for detecting a contact / separation state between the sheets loaded on the loading plate and the feeding roller based on the detection state of the detectable member; a switching means for switching the state of the feeding unit by raising and lowering the feeding unit so that the sheets loaded on the loading plate and the feeding roller are in contact or separated, and a holding unit disposed above the loading section and detachably holding the feeding unit; and a control means for controlling the switching means to a control means for lowering the feeding unit and setting the sheet on the stacking plate to a state where it can be fed based on the detection result of the detection means, wherein when the feeding unit is new, the detectable member is located at a first position where it cannot be detected by the detection means, and when the new feeding unit is attached to the holding unit and the feeding roller is driven, it moves from the first position to a second position where the detectable member protrudes so that it can be detected by the detection means, and when the feeding unit is attached, the control means determines whether the feeding unit is new or not based on the detection result of the detection means when the feeding unit is attached.

[0012] (3) An image forming apparatus comprising: an image forming unit for forming an image on a sheet; and the sheet feeding device according to (1) or (2).

[0013] (4) An image forming apparatus comprising an image forming means for forming an image on a sheet, a sheet feeding device as described in (1) or (2), a door that is opened and closed when replacing the feeding unit, and an opening / closing detection means for detecting the opening / closing state of the door, wherein the control means determines that the feeding unit has been installed when the opening / closing detection means detects a change in the door from an open state to a closed state. [Effects of the Invention]

[0014] According to the present invention, it is possible to automatically detect that the feeding roller has been replaced with a new one. [Brief explanation of the drawings]

[0015] [Figure 1] Schematic cross-sectional view showing the configuration of an image forming apparatus according to first and second embodiments. [Figure 2] FIG. 1 is a cross-sectional view illustrating a configuration of a sheet feeding device according to a first embodiment. [Figure 3] Control block diagram of a sheet feeding device according to a first embodiment [Figure 4] FIG. 1 is a schematic perspective view showing the configuration of a feed roller holding unit and a feed roller unit according to a first embodiment; [Figure 5] 4 is a cross-sectional view showing the state of a detection flag of the feed roller unit according to the first embodiment; FIG. [Figure 6] FIG. 10 is a diagram illustrating the positional relationship between the detection flag of the feed roller unit and the paper surface sensor in the first embodiment. [Figure 7] Flowchart showing a process for detecting a new feed roller unit according to the first embodiment [Figure 8] FIG. 10 is a cross-sectional view illustrating a configuration of a sheet feeding device according to a second embodiment. [Figure 9] Control block diagram of a sheet feeding device according to a second embodiment [Figure 10] Flowchart showing a process for detecting a new feed roller unit according to the second embodiment DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0017] [Image forming device] FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus equipped with a sheet feeding device according to a first embodiment of the present invention. Here, an electrophotographic color laser printer (hereinafter referred to as printer 100) will be used as an example of the image forming apparatus. While printer 100 employs an electrophotographic system, the present invention is not limited to electrophotographic printers and is also applicable to, for example, inkjet printers. In this embodiment, a portion of printer 100 constitutes sheet feeding device 10, which feeds sheets serving as recording materials. However, the sheet feeding device may also be, for example, a feed deck that is attached to printer 100 as an optional device and is capable of storing a large number of sheets.

[0018] 1, the printer 100 includes an image forming unit 100A that forms a toner image to be transferred to a sheet, and a sheet feeding device 10 that feeds a sheet to the image forming unit 100A, both of which are enclosed by dotted lines. The image forming unit 100A includes four photosensitive drums 101Y, 101M, 101C, and 101K on which toner images of four colors, yellow (Y), magenta (M), cyan (C), and black (K), are formed. Note that in FIG. 1, the image forming units that form toner images of each color have the same configuration, and the suffixes Y, M, C, and K at the end of the reference numerals indicate components that form images of yellow, magenta, cyan, and black toner colors, respectively. The image forming unit 100A also includes an endless intermediate transfer belt 102 that comes into contact with the four photosensitive drums 101Y, 101M, 101C, and 101K and onto which the toner images formed on the four photosensitive drums 101Y, 101M, 101C, and 101K are transferred. The image forming unit 100A also includes primary transfer rollers 106Y, 106M, 106C, and 106K that are disposed opposite the photosensitive drums 101Y, 101M, 101C, and 101K and press the intermediate transfer belt 102 against the corresponding photosensitive drums 101. A transfer voltage is applied from a transfer power supply (not shown) to the primary transfer rollers 106Y, 106M, 106C, and 106K, so that the toner images on the photosensitive drums 101Y, 101M, 101C, and 101K are transferred onto the intermediate transfer belt 102. Furthermore, the image forming unit 100A is provided with a secondary transfer roller 105 that transfers the toner images transferred from the photosensitive drums 101Y, 101M, 101C, and 101K onto the intermediate transfer belt 102 onto the sheet S fed from the sheet feeding device 10.

[0019] When the image forming operation is started in the image forming unit 100A, a light beam corresponding to an image signal is irradiated from the laser scanner 103 onto the photosensitive drums 101Y, 101M, 101C, and 101K, the surfaces of which are charged to a constant potential. As a result, electrostatic latent images are formed on the photosensitive drums 101Y, 101M, 101C, and 101K. The electrostatic latent images are then developed with toner stored in the developing cartridges 104Y, 104M, 104C, and 104K, thereby forming visible toner images on the photosensitive drums 101Y, 101M, 101C, and 101K. The toner images formed on the photosensitive drums 101Y, 101M, 101C, and 101K are transferred to the intermediate transfer belt 102 by primary transfer rollers 106Y, 106M, 106C, and 106K. The toner image on the intermediate transfer belt 102 is then conveyed to a secondary transfer portion, which is a nip portion formed by the intermediate transfer belt 102 and a secondary transfer roller 105 coming into contact with each other.

[0020] Meanwhile, in parallel with the image forming operation in the image forming section 100A described above, in the sheet feeding device 10, the sheets S stacked in the sheet storage unit 50 are fed one by one by the feed roller unit 20 and the separation roller unit 40. The fed sheets S are transported to the secondary transfer section by the registration rollers 110, which perform skew correction. Note that since it is necessary to align the position of the toner image transferred onto the intermediate transfer belt 102 with the position of the sheet S to which the toner image is transferred in the transport direction, the registration rollers 110 control the transport speed to adjust the transport timing of the sheet S. Then, in the secondary transfer section, a transfer voltage is applied to the secondary transfer roller 105, so that the toner image on the intermediate transfer belt 102 is transferred to the sheet S.

[0021] The sheet S onto which the toner image has been transferred is then conveyed to a fixing unit 111, where the toner image is heated and pressurized to be fixed to the sheet S. Then, the sheet S onto which the toner image has been fixed is discharged by discharge rollers 112 to a discharge unit 113 at the top of the printer 100.

[0022] An operation unit 114 equipped with an operation panel for inputting data, image formation instructions, etc., and a display unit for displaying information, is provided on the top of the printer 100. Also, a right door 115 that is opened and closed when performing maintenance work such as replacing the feed roller unit 20 is provided on the right side of the printer 100 shown in FIG.

[0023] [Sheet feeding device] Next, a sheet feeding device 10 to which the present invention is applied will be described. FIG. 2 is a cross-sectional view showing the configuration of the sheet feeding device 10. FIG. 2(a) is a diagram showing a state before the sheets S stacked in the sheet storage unit 50 are lifted up toward the feed roller unit 20. On the other hand, FIG. 2(b) shows a state in which the sheets S stacked in the sheet storage unit 50 have been lifted up toward the feed roller unit 20, and the topmost sheet S is positioned at a feeding start position where it abuts against the pickup roller 21. The sheet feeding device 10 is made up of a feed roller unit 20, a feed roller holding unit 30, a separation roller unit 40, a sheet storage unit 50, a feed drive unit 60 (see FIG. 3), and a lift-up drive unit 70 (see FIG. 3).

[0024] (Feed roller unit) The feed roller unit 20 (feed unit) is a feeding means that feeds the sheet S. The feed roller unit 20 has a pickup roller 21 and a feed roller 22 that are feeding members (feed rollers) made of rubber, and a roller holder 23 that is a support means that supports the rotation of the pickup roller 21 and the feed roller 22. In addition, a detection flag 24 (detectable member) that enables a paper surface sensor 32 (described later) to detect the state of the feed roller unit 20 is provided on the left side of the pickup roller 21 in FIG. 2. Furthermore, a feed drive unit 60 (see FIG. 3) that drives the feed roller unit 20 drives the feed roller 22 and the pickup roller 21 to rotate. The idler gear 27 will be described later.

[0025] (Feed roller holding unit) The feed roller holding unit 30 has a feed roller support portion (not shown) that supports the feed roller unit 20, a pick spring 31, and a paper surface sensor 32. The feed roller unit 20 is attached to the feed roller holding unit 30 so as to be rotatable around the feed roller support portion (not shown). The rotation center of the feed roller 22 is located coaxially with the feed roller support portion (not shown), so the feed roller unit 20 is rotatable around the rotation center of the feed roller 22 as the rotation axis. When the feed roller unit 20 is attached to the feed roller holding unit 30, the pick spring 31 presses the roller holder 23 in the direction of the sheet S. The paper surface sensor 32, which is a detection means, is a photointerrupter having a light-emitting portion that emits light and a light-receiving portion that receives the light emitted from the light-emitting portion. The paper surface sensor 32 detects whether the detection flag 24 of the feed roller unit 20 is in a light-blocking state where it blocks light from the light-emitting unit, or a light-transmitting state where it does not block light from the light-emitting unit, and outputs the result to a state determination unit 81 (see FIG. 3) of the control unit 80, which will be described later. For example, when the feed roller unit 20 is in the state shown in FIG. 2(a), the detection flag 24 is in a state where it does not block light from the light-emitting unit of the paper surface sensor 32, and the paper surface sensor 32 outputs a light-transmitting state (a state where it does not detect the detection flag 24). On the other hand, when the feed roller unit 20 is in the state shown in FIG. 2(b), the detection flag 24 is in a state where it blocks light from the light-emitting unit of the paper surface sensor 32, and the paper surface sensor 32 outputs a light-blocking state (a state where it detects the detection flag 24).

[0026] (Separation roller unit) The separation roller unit 40 has a separation roller 41 that separates the sheets S one by one, a cover member 42 that holds the separation roller 41, and a separation spring 43. The separation roller 41 is pressed toward the feed roller 22 by the separation spring 43. When the pickup roller 21 of the feed roller unit 20 feeds multiple sheets S to a nip portion where the feed roller 22 and the separation roller 41 abut against each other, the separation roller 41 separates the sheets S one by one and transports them downstream in the transport path.

[0027] In the sheet feeding device 10 of this embodiment, the feed roller unit 20 and the separation roller unit 40 are configured to be easily replaceable by a user or a service technician. More specifically, when replacing the feed roller unit 20 or the separation roller unit 40, the right door 115 (FIG. 1) is opened, and the separation roller unit 40 and the feed roller unit 20 that are currently installed can be removed by pulling them out in the right direction indicated by X in the figure. When installing them, the feed roller unit 20 and the separation roller unit 40 can be attached (mounted) by inserting them in the left direction indicated by X in the figure. The open / closed state of the right door 115, which is a door, can be detected by a right door sensor 116 (see FIG. 3), which is an open / close detection means.

[0028] (Seat storage unit) The sheet storage unit 50 is detachably attached to the sheet feeding device 10 and has a storage cassette 51 that can store a plurality of sheets S. The storage cassette 51 is a stacking section on which the sheets S are stacked, and has a stacking plate 52 that is a lift-up means that raises and lowers the stacked sheets S. A lift-up drive unit 70 (see FIG. 3), which will be described later, transmits drive to a lift-up gear (not shown) attached to the stacking plate 52, and raises and lowers the stacking plate 52 as shown in FIG. 2(b).

[0029] [Sheet feeding device control unit] 3 is a control block diagram showing the configuration of a control unit of the sheet feeding device 10. The control unit 80, which is a control means for controlling the sheet feeding device 10, has a state determination unit 81 that determines the state based on signals output from each sensor, and a drive control unit 82 that controls the drive unit based on the determination of the state determination unit 81 and the timing of conveying the sheets S. The state determination unit 81 determines the state of the feed roller unit 20 based on the light-transmitting state or light-blocking state output by the above-mentioned paper surface sensor 32 in accordance with the state of the detection flag 24 of the feed roller unit 20. The state determination unit 81 also determines the open / closed state of the right door 115 based on the detection result of the above-mentioned right door sensor 116. The drive control unit 82 controls the feed drive unit 60 that drives the feed roller unit 20 to feed the sheets S, and the lift-up drive unit 70 (drive unit) that raises and lowers the stacking plate 52 on which the sheets S are stacked.

[0030] [Sheet feeding operation] Next, an operation of the sheet feeding device 10 to feed the sheet S stored in the sheet storage unit 50 to a conveyance path to a secondary transfer unit of the image forming unit 100A of the printer 100 will be described. The control unit 80 instructs the drive control unit 82 to drive the lift-up drive unit 70. The drive control unit 82 drives the lift-up drive unit 70 to lift up the stacking plate 52 of the sheet storage unit 50. As a result, the sheets S stacked on the stacking plate 52 (on the stacking plate) rise toward the pickup roller 21, and the pickup roller 21 comes into contact with the uppermost sheet S. At this time, the pickup roller 21 is pressed downward in FIG. 2 by the pick spring 31 via the roller holder 23. The roller holder 23 is held rotatably about the rotation axis of the feed roller 22. Therefore, the sheets S stacked on the stacking plate 52 are lifted up against the pressing force of the pick spring 31, and the roller holder 23 supporting the pickup roller 21 is also lifted up by the pressure from the sheets S. Then, the detection flag 24 attached to the roller holder 23 also rises upward in FIG. 2 and is lifted up to a position where it blocks the light emitted from the light-emitting unit of the paper surface sensor 32 (FIG. 2(b)). As a result, the detection state output by the paper surface sensor 32 to the state determination unit 81 of the control unit 80 changes from the light-transmitting state to the light-blocking state.

[0031] When the state determination unit 81 detects a change in the detection state output by the paper surface sensor 32, i.e., a change in the state of the detection flag 24, it notifies the control unit 80 of the change in the state of the detection flag 24. Based on the notification of the change in the state of the detection flag 24 from the state determination unit 81, the control unit 80 determines that the sheets S stacked on the stack plate 52 of the sheet storage unit 50 have been set to a position where they can be fed by the pickup roller 21. Then, the control unit 80 instructs the drive control unit 82 to stop driving the lift-up drive unit 70, and the drive control unit 82 stops driving the lift-up drive unit 70. By performing the above-mentioned operations, the printer 100 is ready to feed the top sheet S stacked on the stack plate 52 to the image forming unit 100A. Thereafter, the control unit 80 instructs the drive control unit 82 to drive the feed drive unit 60, and the drive control unit 82 starts driving the feed drive unit 60 to transport the sheets S stacked on the stack plate 52 to the image forming unit 100A.

[0032] When the pickup roller 21 feeds the sheets S to the image forming unit 100A, the pickup roller 21 is pressed by the pick spring 31 via the roller holder 23, and thus moves downward in FIG. 2 by the number of sheets S fed. As a result, the detection flag 24 also moves downward in FIG. 2, and the paper surface sensor 32 detects a change in state from the light-blocking state to the light-transmitting state. When the state determination unit 81 detects that the detection state output from the paper surface sensor 32 has changed from the light-blocking state to the light-transmitting state, it notifies the control unit 80 of the change in state of the detection flag 24. The control unit 80 instructs the drive control unit 82 to drive the lift-up drive unit 70, and the drive control unit 82 drives the lift-up drive unit 70. When the detection state output from the paper surface sensor 32 changes from the light-transmitting state to the light-blocking state, the control unit 80 stops the lift-up drive unit 70. By the sheet feeding control described above, the topmost sheet S stacked on the stacking plate 52 is controlled to come into contact with the pickup roller 21 at an appropriate position and be transported to the image forming section 100A.

[0033] [Feed roller unit configuration] Next, a detailed configuration of the feed roller unit 20 will be described. Fig. 4 is a diagram illustrating the configuration of the feed roller unit 20. Fig. 4(a) is a schematic perspective view of the feed roller unit 20 as viewed from the upper right direction in Fig. 2, and Fig. 4(b) is a schematic perspective view of the feed roller unit 20 as viewed from the lower left direction in Fig. 2.

[0034] As shown in FIGS. 4(a) and 4(b), the pickup roller 21 and the feed roller 22 are rotatably supported by a roller holder 23. A pickup roller gear 25 is integrally attached to one end of the pickup roller 21, and the other end is rotatably supported by the roller holder 23. A feed roller gear 26 is integrally attached to the end of the feed roller 22 on the same side as the one end of the pickup roller 21, and the other end is rotatably supported by the roller holder 23. An idler gear 27 for transmitting the drive of the feed roller gear 26 to the pickup roller gear 25 is rotatably supported by the roller holder 23 between the pickup roller gear 25 and the feed roller gear 26. The roller holder 23 is also provided with guide portions 28a and 28b as guides for regulating the attachment / detachment direction of the feed roller unit 20 and preventing incorrect attachment when a user or service technician attaches or detaches the feed roller unit 20. The guide portion 28a is also referred to as the guide portion F, and the guide portion 28b is also referred to as the guide portion R. In this embodiment, in order to prevent the feed roller unit 20 from being erroneously attached, an arrow (guide direction) indicating the insertion direction of the feed roller unit 20 is formed on the surface of the guide portion 28b shown in FIG.

[0035] The control by the control unit 80 to set the sheets S stacked on the stacking plate 52 of the sheet storage unit 50 to a position where they can be fed by the pickup roller 21 has been described above. Next, the control up to the feeding of the sheets S by the feed roller unit 20 will be described. The control unit 80 instructs the drive control unit 82 to drive the feed drive unit 60 in order to feed the sheets S stacked on the stacking plate 52. When the drive control unit 82 controls the feed drive unit 60 to start driving, the drive of the feed drive unit 60 is transmitted to the feed roller gear 26 via a gear train (not shown) provided in the feed roller holding unit 30. When the feed roller gear 26 is driven, the feed roller 22 is driven to rotate and the idler gear 27 is driven. Then, when the idler gear 27 is driven, the pickup roller gear 25 is driven to rotate the pickup roller 21, and the feeding operation of the sheets S is started.

[0036] [Detection flag control] 5A and 5B are cross-sectional views illustrating the state of the detection flag 24 of the feed roller unit 20, with Fig. 5A showing the state when the detection flag 24 is in the retracted position and Fig. 5B showing the state when the detection flag 24 is in the protruding position. As described above, the detection flag 24 transmits or blocks light from the light-emitting unit of the paper surface sensor 32, thereby allowing the paper surface sensor 32 to detect the state of the detection flag 24. The control unit 80 controls the height to which the stacking plate 52 of the sheet storage unit 50 is lifted, based on the state of the detection flag 24 detected by the paper surface sensor 32.

[0037] The feed roller unit 20 has a configuration in which the detection flag 24 can move from a retracted position shown in Fig. 5(a) to a protruding position shown in Fig. 5(b). Next, a method for holding the retracted position and protruding position of the detection flag 24 of the feed roller unit 20, which is a characteristic configuration of the present invention, and a method for moving the detection flag 24 from the retracted position to the protruding position will be described with reference to Fig. 5.

[0038] In the detection flag 24 shown in FIG. 5(a), the protrusion 24a protrudes toward the pickup roller 21, and when the detection flag 24 is located in the retracted position, the protrusion 24a is held in a state in which the rubber material of the pickup roller 21 is depressed. Furthermore, as shown in FIG. 5(a), the contact portion 24b is an inclined surface against which the state-retaining spring 29 abuts when the detection flag 24 is located in the retracted position (first position). The state-retaining spring 29 (pressure portion) is provided to maintain the state of the detection flag 24, and is made of a torsion coil spring. Meanwhile, as shown in FIG. 5(b), the contact portion 24c is an inclined surface against which the state-retaining spring 29 abuts when the detection flag 24 is located in the protruding position (second position). Furthermore, the abutment portion 24d is an abutment portion provided on the detection flag 24 side, and the abutment portion 23a is an abutment portion provided on the roller holder 23 side. As will be described later, when the detection flag 24 moves to the left in the figure, the abutment portion 24a of the detection flag 24 abuts against the abutment portion 23a of the roller holder 23 (Figure 5(b)), thereby preventing the detection flag 24 from moving further to the left in the figure.

[0039] As shown in Figures 5(a) and 5(b), both arms of the state-retention spring 29 are fixed to the roller holder 23. When the detection flag 24 moves from a state in which it abuts against the abutment portion 24b shown in Figure 5(a) to a state in which it abuts against the abutment portion 24c shown in Figure 5(b), the coil portion of the state-retention spring 29 moves in the up-down direction in the figure, following the shape of the abutting detection flag 24. Note that although the detection flag 24 can move in the left-right direction in Figure 5, its movement in the up-down direction and depth direction in Figure 5 is restricted by the roller holder 23.

[0040] First, a configuration will be described in which the detection flag 24 maintains the retracted position when it is located at the retracted position shown in Fig. 5(a). As described above, when the detection flag 24 is located at the retracted position, the coil portion of the state-maintaining spring 29 abuts against the abutting portion 24b of the detection flag 24. As shown in Fig. 5(a), the coil portion of the state-maintaining spring 29 presses against the abutting portion 24b in the upward direction in the figure. However, because the abutting portion 24b has an inclined surface, the direction of the pressing force applied by the coil portion of the state-maintaining spring 29 is converted into a direction along the inclined surface (the retracted direction), thereby maintaining the state of the detection flag 24 at the retracted position.

[0041] Next, the operation of the detection flag 24 when it moves from the retracted position to the protruding position will be described. When the detection flag 24 is located in the retracted position where the coil portion of the state-maintaining spring 29 is in contact with the contact portion 24b, the protrusion 24a of the detection flag 24 is maintained in a state in which it depresses the rubber material of the pickup roller 21. Under the control of the control unit 80, the drive of the feed drive unit 60 is transmitted to the pickup roller 21 via the feed roller gear 26, the idler gear 27, and the pickup roller gear 25, and the pickup roller 21 begins to rotate in the direction of the arrow (counterclockwise direction) in FIG. 5(a). Then, the protrusion 24a of the detection flag 24 is pushed in the rotation direction (protruding direction) of the pickup roller 21 against the holding force of the state-maintaining spring 29 (the pressing force against the detection flag 24). As a result, the contact point of the detection flag 24 with the coil portion of the state-maintaining spring 29 moves from the contact portion 24b to the contact portion 24c. Even at the neutral point where the direction of the pressing force of state-maintaining spring 29 against detection flag 24 changes, i.e., at the peak of the inclined surface between contact portions 24b and 24c of detection flag 24, convex portion 24a maintains the state in which it has depressed the rubber of pickup roller 21. Therefore, the coil portion of state-maintaining spring 29 that contacts detection flag 24 moves beyond the neutral point toward the inclined surface of contact portion 24c, and detection flag 24 is reliably pushed toward the protruding position (leftward in FIG. 5(b)).

[0042] Furthermore, because the contact portion 24c of the detection flag 24 has an inclined surface, the direction of the pressing force applied from the coil portion of the state-maintaining spring 29 is converted into a direction along the inclined surface (the protruding direction), thereby moving the detection flag 24 toward the protruding position. When the detection flag 24 moves in the protruding direction (leftward in the figure), the abutting portion 24d of the detection flag 24 abuts against the abutting portion 23a of the roller holder 23, completing the movement of the detection flag 24. Note that at the protruding position where the abutting portion 24d of the detection flag 24 abuts against the abutting portion 23a of the roller holder 23, the coil portion of the state-maintaining spring 29 continues to abut against the abutting portion 24c of the detection flag 24. As a result, the detection flag 24 is pressed toward the protruding position by the coil portion of the state-maintaining spring 29, and the detection flag 24 maintains its state in the protruding position. When the coil portion of state-maintaining spring 29 is in the protruding position in which it abuts against abutting portion 24c of detection flag 24, convex portion 24a of detection flag 24 is separated from the rubber material of pickup roller 21 and does not interfere with pickup roller 21. Therefore, once detection flag 24 moves to the protruding position, it does not return to the retracted position in which the coil portion of state-maintaining spring 29 abuts against abutting portion 24b of detection flag 24.

[0043] As described above, by configuring the detection flag 24 to be movable, it is possible to move the detection flag 24 from the retracted position to the protruding position. Furthermore, by interfering with the rubber material of the pickup roller 21 and providing the state-maintaining spring 29, it is possible to reliably move the detection flag 24 from the retracted position to the protruding position using a small space.

[0044] [Detection of new feed roller unit 20] Next, detection of a new feed roller unit 20 will be described. FIG. 6(a) shows the following state. That is, the feed roller unit 20, with the detection flag 24 held in the retracted position, is inserted (attached) into the feed roller holding unit 30, and the lift-up drive unit 70 is driven to a position where the sheet S can be fed by the pickup roller 21. At this time, the detection flag 24 is located away from the paper surface sensor 32, so the paper surface sensor 32 is in a light-transmitting state and does not detect the detection flag 24. On the other hand, FIG. 6(b) shows the following state. That is, the feed roller unit 20, with the detection flag 24 held in the protruding position, is inserted (attached) into the feed roller holding unit 30, and the lift-up drive unit 70 is driven to a position where the sheet S can be fed by the pickup roller 21. At this time, the detection flag 24 is in a state where it blocks light from the light-emitting element of the paper surface sensor 32, so the paper surface sensor 32 detects the detection flag 24.

[0045] First, the positional relationship of the detection flag 24 when replacing the feed roller unit 20 will be described. As described above, in a new feed roller unit 20, the detection flag 24 is located in the retracted position. When replacing the feed roller unit 20 with a new one, the user or service person opens the right door 115 and removes the separation roller unit 40 and feed roller unit 20 that were in use. Then, the user or service person installs the new feed roller unit 20 and separation roller unit 40 and closes the right door 115. At this time, the detection flag 24 is in the state shown in FIG. 2(a). Then, the lift-up drive unit 70 is driven to lift up the stacking plate 52 of the sheet storage unit 50, causing the sheets S stacked on the stacking plate 52 to rise toward the pickup roller 21, bringing the pickup roller 21 into contact with the uppermost sheet S. By driving the lift-up drive unit 70 for a predetermined time, the feed roller unit 20 is set to the state shown in FIG. 6(a) in which the sheets S stacked on the stacking plate 52 of the sheet storage unit 50 can be fed by the pickup roller 21. When the feed roller unit 20 is then driven, as described above, the detection flag 24 moves from the retracted position to the protruding position, and sets the paper surface sensor 32 to a light-blocking state as shown in FIG. 6(b). Note that in the feed roller unit 20 in which the detection flag 24 has moved to the protruding position, the detection flag 24 continues to be in the protruding position.

[0046] [Control sequence for replacing the feed roller unit] Next, a control sequence for detecting the replacement operation of the feed roller unit 20 and detecting that the feed roller unit 20 is new will be described. Fig. 7 is a flowchart showing the control sequence for replacing the feed roller unit 20. The process shown in Fig. 7 is executed by the control unit 80 when the power of the printer 100 is turned on and the control unit 80 is started. Note that when the right door 115 is opened or closed, the stacking plate 52 is set to a state (hereinafter referred to as the initial state) in which it is located at the bottom of the storage cassette 51 shown in Fig. 2(a).

[0047] In step (hereinafter referred to as S) 201, the control unit 80 instructs the state determination unit 81 to monitor the open state of the right door 115, and determines whether the state determination unit 81 has detected the open state of the right door 115 based on the detection result of the right door sensor 116. If the control unit 80 determines that the state determination unit 81 has detected the open state of the right door 115, the process proceeds to S202, and if the control unit 80 determines that the state determination unit 81 has not detected the open state of the right door 115, the process returns to S201.

[0048] In S202, the control unit 80 instructs the state determination unit 81 to monitor whether the right door 115 is closed (closed state), and the state determination unit 81 determines whether it has detected that the right door 115 is closed (closed state) based on the detection result of the right door sensor 116. If the state determination unit 81 determines that it has detected that the right door 115 is closed, the control unit 80 determines that the right door 115 has been opened or closed and that the replacement process of the feed roller unit 20 has been completed, and proceeds with the process to S203. On the other hand, if the control unit 80 determines that the state determination unit 81 has not detected that the right door 115 is closed, the control unit 80 determines that the right door 115 is open and that the replacement process of the feed roller unit 20 has not been completed, and returns the process to S202.

[0049] In S203, the control unit 80 instructs the drive control unit 82 to drive the lift-up drive unit 70 in order to determine whether the feed roller unit 20 is installed, and the drive control unit 82 drives the lift-up drive unit 70 in the lift-up direction for a predetermined time. Note that the predetermined time refers to the time it takes for the lift-up drive unit 70 to be driven in the lift-up direction and for the feed roller unit 20 to move to the state shown in FIG. 6(a) where the sheets S loaded on the stacking plate 52 in the initial state can be fed by the pickup roller 21.

[0050] In S204, the control unit 80 acquires the detection state of the detection flag 24 of the paper surface sensor 32 from the state determination unit 81. Then, based on the detection result of the paper surface sensor 32 acquired from the state determination unit 81, the control unit 80 determines whether the paper surface sensor 32 detects the detection flag 24 (detects the light-blocking state). As described above, the paper surface sensor 32 does not detect the detection flag 24 when it is in the light-transmitting state where it detects light from the light-emitting unit, and detects the detection flag 24 when it is in the light-blocking state where it does not detect light from the light-emitting unit. If the control unit 80 determines that the paper surface sensor 32 detects the detection flag 24 (light-blocking state), the process proceeds to S205. If the control unit 80 determines that the paper surface sensor 32 does not detect the detection flag 24 (light-transmitting state), the process proceeds to S206. In S205, the control unit 80 determines that the feed roller unit 20 is installed but has not been replaced with a new feed roller unit 20, and returns the process to S201. A specific example of proceeding to processing S205 is when the right door 115 is opened and closed but the feed roller unit 20 is not replaced, such as after a jam has been cleared when a sheet S has become stuck on the conveying path.

[0051] In S206, the control unit 80 instructs the drive control unit 82 to drive the lift-up drive unit 70 in order to return the loading plate 52 to its initial state, and the drive control unit 82 drives the lift-up drive unit 70 in the lift-down direction for a predetermined time.

[0052] In S207, because the paper surface sensor 32 does not detect the detection flag 24, the control unit 80 determines that either the feed roller unit 20 is not installed or a new feed roller unit 20 has been installed. Therefore, the control unit 80 instructs the drive control unit 82 to drive the feed drive unit 60, and the drive control unit 82 drives the feed drive unit 60 for a certain period of time. For example, if a new feed roller unit 20 has been installed, when the feed drive unit 60 is driven, the feed roller gear 26 of the feed roller unit 20 is driven. Then, the pickup roller gear 25 and the pickup roller 21 are driven via the feed roller gear 26. Then, the detection flag 24 moves from the retracted position (FIG. 5(a)) to the protruding position (FIG. 5(b)).

[0053] In S208, the control unit 80 instructs the drive control unit 82 to drive the lift-up drive unit 70 to determine whether the feed roller unit 20 is installed, and the drive control unit 82 drives the lift-up drive unit 70 in the lift-up direction for a predetermined time.

[0054] In S209, the control unit 80 acquires the detection state of the detection flag 24 of the paper surface sensor 32 from the state determination unit 81, and determines whether the paper surface sensor 32 is detecting the detection flag 24 (detecting a light-blocking state) based on the acquired detection result of the paper surface sensor 32. If the control unit 80 determines that the paper surface sensor 32 is detecting the detection flag 24 (light-blocking state), the process proceeds to S210, and if it determines that the paper surface sensor 32 is not detecting the detection flag 24 (light-transmitting state), the process proceeds to S211. In S210, the control unit 80 determines that the feed roller unit 20 has been replaced with a new one, and returns the process to S201.

[0055] In S211, the control unit 80 determines that the feed roller unit 20 is not installed, notifies the user by displaying a message on the display unit of the operation unit 114 indicating that the feed roller unit 20 is not installed, and returns the process to S201. A specific example of the process proceeding to S211 is when the user removes the feed roller unit 20 in order to replace it, and then closes the right door 115 without installing the feed roller unit 20.

[0056] As described above, in this embodiment, the paper surface sensor 32 detects the position of the pickup roller 21 and also detects whether the feed roller unit 20 is new when the right door 115 is opened or closed. By detecting the new feed roller unit 20, it is possible to automatically detect replacement of the feed roller unit 20 with a new one without increasing costs by using only one sensor. Furthermore, movement of the detection flag 24 of the feed roller unit 20 from the retracted position to the protruding position is achieved in the narrow space inside the feed roller unit 20 by using the protrusion 24a that interferes with the rubber material of the pickup roller 21 and the state-maintaining spring 29.

[0057] As described above, according to this embodiment, it is possible to automatically detect that the feeding roller has been replaced with a new one. [Example]

[0058] In the first embodiment, a control was described in which the top sheet S stacked on the stack plate is brought into contact with the pickup roller and set to a position where it can be fed by controlling the lift-up of the stack plate of the sheet storage unit. In the second embodiment, a control will be described in which the top sheet S is brought into contact with the pickup roller and set to a position where it can be fed, with a configuration different from that of the first embodiment. Note that the image forming apparatus of this embodiment has the same configuration as the image forming apparatus of the first embodiment, and the same devices and members are designated by the same reference numerals as in the first embodiment, and therefore the description here will be omitted.

[0059] [Configuration of the sheet feeding device] FIG. 8 is a cross-sectional view showing the configuration of the sheet feeding device 10 of this embodiment. FIG. 8(a) shows a state in which the top sheet S stacked on the stacking plate 52 of the sheet storage unit 50 is positioned at a feeding start position where it abuts against the pickup roller 21. On the other hand, FIG. 8(b) shows a state in which the top sheet S stacked on the stacking plate 52 of the sheet storage unit 50 is separated from the pickup roller 21. The configurations of the feed roller unit 20 and the separation roller unit 40 shown in FIGS. 8(a) and 8(b) are the same as those of the first embodiment. On the other hand, the feed roller holding unit 30 of this embodiment differs from the feed roller holding unit 30 of the first embodiment in that the paper surface sensor 32 and the pick spring 31 are eliminated and a contact / separation sensor 132 and a pickup roller contact / separation arm 133 are provided. Furthermore, the sheet storage unit 50 of this embodiment differs from the sheet storage unit 50 of the first embodiment in that it has a sheet pressing spring 151 that presses the stacking plate 52 on which the sheets S are stacked toward the pickup roller 21.

[0060] The contact / separation sensor 132 is a photointerrupter having a light-emitting element that emits light and a light-receiving element that receives the light emitted from the light-emitting element, similar to the paper surface sensor 32 of the first embodiment. The contact / separation sensor 132 detects whether the detection flag 24 of the feed roller unit 20 is in a light-blocking state where it blocks light from the light-emitting element, or in a light-transmitting state where it does not block light, and outputs the detection result to the state determination unit 81 of the control unit 80. In addition, the pickup roller contact / separation arm 133 (hereinafter referred to as the contact / separation arm 133) switches the pickup roller 21 between a contact state where it contacts the uppermost sheet S stacked on the stacking plate 52 of the sheet storage unit 50, and a separated state. The contact / separation arm 133 has a rotation center coaxial with a feed roller support unit (not shown) that supports the feed roller unit 20, and is rotatable. The feed roller unit 20 also has a rotation center coaxial with the feed roller support unit (not shown). That is, the feed roller unit 20 and the contact / separation arm 133 have a rotation center on the same axis and are rotatable.

[0061] [Sheet feeding device control unit] FIG. 9 is a control block diagram showing the configuration of a control unit of the sheet feeding device 10 of this embodiment. The control unit 80, which controls the sheet feeding device 10, includes a state determination unit 81 that determines the state based on signals output from each sensor, and a drive control unit 82 that controls each drive unit. The state determination unit 81 determines the contact / separation state of the pickup roller 21 in response to a signal output from the contact / separation sensor 132 based on the light-transmitting or light-blocking state of the detection flag 24 of the feed roller unit 20. The state determination unit 81 also determines the open / closed state of the right door 115 based on the detection result of the right door sensor 116. The drive control unit 82 controls the feed drive unit 60 that drives the feed roller unit 20 to feed the sheet S, and the switching drive unit 170 that rotates the contact / separation arm 133 to switch the contact / separation state between the pickup roller 21 and the sheet S. The switching drive unit 170 branches the drive of the feed drive unit 60 and is configured to operate only when the feed drive unit 60 is rotated in reverse. The switching drive unit 170 rotates a cam (not shown) connected to the contact / separation arm 133 to switch the state of the contact / separation arm 133 between a contact state in which the pickup roller 21 and the sheet S are in contact with each other, and a separated state in which they are separated from each other.

[0062] [Pickup roller status control] Next, the position control of the pickup roller 21 by switching the state of the contact / separation arm 133 and the contact / separation relationship between the pickup roller 21 and the uppermost sheet S stacked on the stacking plate 52 will be described.

[0063] First, the relationship between the light-blocking state and light-transmitting state of the contact / separation sensor 132 determined by the detection flag 24 and the contact state and separation state of the top sheet S of the pickup roller 21 will be described. FIG. 8A shows a state in which the top sheet S stacked on the stacking plate 52 is in contact with the pickup roller 21. At this time, the detection flag 24 is located below the contact / separation sensor 132 in the drawing, and the contact / separation sensor 132 is in a light-transmitting state in which the light-receiving portion receives light from the light-emitting portion. Therefore, the state determination unit 81 determines that the pickup roller 21 is in contact with the top sheet S stacked on the stacking plate 52 based on the detection result of the detection flag 24 from the contact / separation sensor 132. On the other hand, FIG. 8B shows a state in which the top sheet S stacked on the stacking plate 52 is separated from the pickup roller 21. At this time, the detection flag 24 is located in a state in which it blocks light from the light-emitting portion of the contact / separation sensor 132. Therefore, based on the detection result of the detection flag 24 from the contact / separation sensor 132, the state determination unit 81 determines that the pickup roller 21 is separated from the uppermost sheet S stacked on the stacking plate 52. When the feed roller unit 20 is replaced and inserted (attached) into the feed roller holding unit 30, the feed roller unit 20 will be in the state shown in FIG. 8B. In FIG. 8B, the contact / separation sensor 132 is shielded from light by the detection flag 24, so this shows a state in which a feed roller unit 20 that is not new is attached. When a new feed roller unit 20 is attached, the detection flag 24 is located at the retracted position, so the contact / separation sensor 132 is not shielded from light by the detection flag 24 and is therefore in a light-transmitting state.

[0064] First, the control for switching the state of the pickup roller 21 from a state separated from the uppermost sheet S to a state in contact with it will be described. The control unit 80 instructs the drive control unit 82 to switch the state of the pickup roller 21 from a state separated from the uppermost sheet S to a state in contact with it. In order to transition the pickup roller 21 to a state in contact with the uppermost sheet S, the drive control unit 82 reversely rotates the feeding drive unit 60 to drive the switching drive unit 170, and rotates the contact / separation arm 133 in direction B (counterclockwise) in FIG. 8(a). The contact / separation arm 133 and the roller holder 23 are connected with a certain amount of play, and when the contact / separation arm 133 and the roller holder 23 come into contact with each other, the roller holder 23 rotates in direction B. Meanwhile, the sheets S stacked on the stack plate 52 are lifted up toward the pickup roller 21 by the sheet pressure spring 151. As roller holder 23 rotates in direction B, pickup roller 21 also rotates in direction B and comes into contact with the uppermost sheet S stacked on stacking plate 52. As a result, the position of detection flag 24 drops toward stacking plate 52, and the state of contact / separation sensor 132 changes from a light-blocking state in which it is blocked by detection flag 24 to a light-transmitting state. When drive control unit 82 detects the state change of contact / separation sensor 132 from the light-blocking state to the light-transmitting state, it drives switching drive unit 170 a certain amount and then stops the reverse rotation of feed drive unit 60, thereby stopping the drive of switching drive unit 170. In this way, control unit 80 moves pickup roller 21 to a position where it comes into contact with sheet S, and also moves pickup roller 21 so that an appropriate pressing force is applied from sheet pressure spring 151 to pickup roller 21.

[0065] Next, the control for switching the state of the pickup roller 21 from a state in contact with the uppermost sheet S to a state separated from it will be described. The control unit 80 instructs the drive control unit 82 to switch the state of the pickup roller 21 from a state in contact with the uppermost sheet S to a state separated from it. In order to transition the pickup roller 21 to a state separated from the uppermost sheet S, the drive control unit 82 reversely rotates the feeding drive unit 60 to drive the switching drive unit 170 and rotates the contact / separation arm 133 in the C direction (clockwise direction) in FIG. 8( a). When the backlash between the contact / separation arm 133 and the roller holder 23 disappears and the contact / separation arm 133 and the roller holder 23 come into contact with each other, the roller holder 23 rotates in the C direction. As the roller holder 23 rotates in the C direction, the pickup roller 21 also rotates in the C direction and separates from the uppermost sheet S stacked on the stacking plate 52. As a result, the position of the detection flag 24 rises toward the feed roller holding unit 30, and the state of the contact / separation sensor 132 changes from a light-transmitting state in which it is not blocked by the detection flag 24 to a light-transmitting state. When the drive control unit 82 detects the change in state of the contact / separation sensor 132 from the light-transmitting state to the light-blocking state, it drives the switching drive unit 170 a certain amount, then stops the reverse rotation of the feeding drive unit 60, and stops driving the switching drive unit 170. While the switching drive unit 170 is being driven a certain amount, the stacking plate 52 pressed by the sheet pressure spring 151 comes into contact with a stopper (not shown) provided in the sheet storage unit 50 and cannot be lifted up any further. In this way, the control unit 80 ends the separation operation of the pickup roller 21 at a position where the switching drive unit 170 has been driven a certain amount from the state in which the pickup roller 21 was separated from the sheet S.

[0066] [Detection of new feed roller unit 20] Next, a method for detecting whether the feed roller unit 20 is new in this embodiment will be described. Here, FIG. 8B illustrates a state in which the feed roller unit 20 has been replaced and inserted (mounted) into the feed roller holding unit 30. In FIG. 8B, the detection flag 24 has moved to the protruding position (FIG. 6B), and the contact / separation sensor 132 is set to a light-blocking state, indicating that a new feed roller unit 20 has been mounted. On the other hand, if the feed roller unit 20 is new, the detection flag 24 is in the retracted position (FIG. 6A), and the contact / separation sensor 132 is set to a light-transmitting state. The control unit 80 instructs the drive control unit 82 to drive the feed drive unit 60. When the drive control unit 82 drives the feed drive unit 60 for a certain period of time, the detection flag 24 moves from the retracted position (FIG. 6A) to the protruding position (FIG. 6B). As a result, the detection flag 24 is in the state shown in Fig. 8(b), and the contact / separation sensor 132 is set to a light-blocking state. In this way, the contact / separation sensor 132 of this embodiment and the paper surface sensor 32 of the first embodiment have the same configuration as the detection flag 24, and it is possible to detect whether the feed roller unit 20 is new based on the flowchart of Fig. 10, which will be described below.

[0067] [Control sequence for replacing the feed roller unit] Next, a control sequence for detecting the replacement operation of the feed roller unit 20 and detecting a new feed roller unit 20 in this embodiment will be described. Fig. 10 is a flowchart showing the control sequence for replacing the feed roller unit 20. The process shown in Fig. 10 is executed by the control unit 80 when the power of the printer 100 is turned on and the control unit 80 is started up.

[0068] In S301, the control unit 80 instructs the state determination unit 81 to monitor the open state of the right door 115, and the state determination unit 81 determines whether or not the open state of the right door 115 has been detected based on the detection result of the right door sensor 116. If the control unit 80 determines that the state determination unit 81 has detected the open state of the right door 115, the process proceeds to S302, and if the control unit 80 determines that the state determination unit 81 has not detected the open state of the right door 115, the process returns to S301.

[0069] In S302, the control unit 80 instructs the state determination unit 81 to monitor whether the right door 115 is closed (blocked state), and the state determination unit 81 determines whether it has detected that the right door 115 is closed (blocked state) based on the detection result of the right door sensor 116. If the state determination unit 81 determines that it has detected that the right door 115 is closed, the control unit 80 determines that the right door 115 has been opened or closed and that the replacement process for the feed roller unit 20 has been completed, and proceeds with the process to S303. On the other hand, if the control unit 80 determines that the state determination unit 81 has not detected that the right door 115 is closed, the control unit 80 determines that the right door 115 is open and that the replacement process for the feed roller unit 20 has not been completed, and returns the process to S302.

[0070] In S303, the control unit 80 acquires the detection state of the detection flag 24 of the contact / separation sensor 132 from the state determination unit 81. As described above, the contact / separation sensor 132 does not detect the detection flag 24 when in the light-transmitting state where it detects light from the light-emitting unit, and detects the detection flag 24 when in the light-blocking state where it does not detect light from the light-emitting unit.

[0071] In S304, the control unit 80 determines whether the contact / separation sensor 132 has detected the detection flag 24 (detected a light-blocking state) based on the detection result of the contact / separation sensor 132 obtained from the state determination unit 81. If the control unit 80 determines that the contact / separation sensor 132 has detected the detection flag 24 (light-blocking state), the process proceeds to S305, and if the control unit 80 determines that the contact / separation sensor 132 has not detected the detection flag 24 (light-transmitting state), the process proceeds to S306. In S305, the control unit 80 determines that the feed roller unit 20 is installed but has not been replaced with a new feed roller unit 20, and returns the process to S301.

[0072] In S306, because the contact / separation sensor 132 does not detect the detection flag 24, the control unit 80 determines that either the feed roller unit 20 is not installed or a new feed roller unit 20 has been installed. Therefore, the control unit 80 instructs the drive control unit 82 to drive the feed drive unit 60, and the drive control unit 82 drives the feed drive unit 60 for a certain period of time. For example, when a new feed roller unit 20 is installed ( FIG. 6(a) ), when the feed drive unit 60 is driven, the feed roller gear 26 of the feed roller unit 20 is driven. Then, the pickup roller gear 25 and the pickup roller 21 are driven via the feed roller gear 26. Then, the detection flag 24 moves from the retracted position ( FIG. 6(a) ) to the protruding position ( FIG. 6(b) ), blocking light from the contact / separation sensor 132, and the contact / separation sensor 132 detects the detection flag 24.

[0073] In S307, the control unit 80 acquires the detection state of the detection flag 24 of the contact / separation sensor 132 from the state determination unit 81, and determines whether the contact / separation sensor 132 is detecting the detection flag 24 (detecting a light-blocking state) based on the acquired detection result. If the control unit 80 determines that the contact / separation sensor 132 is detecting the detection flag 24 (light-blocking state), the process proceeds to S308, and if the control unit 80 determines that the contact / separation sensor 132 is not detecting the detection flag 24 (light-transmitting state), the process proceeds to S309. In S308, the control unit 80 determines that the feed roller unit 20 has been replaced with a new one, and returns the process to S301.

[0074] In S309, the control unit 80 determines that the feed roller unit 20 is not installed, notifies the user by displaying a message on the display unit of the operation unit 114 indicating that the feed roller unit 20 is not installed, and returns the process to S301. A specific example of the process proceeding to S309 is when the user removes the feed roller unit 20 in order to replace it, and then closes the right door 115 without installing the feed roller unit 20.

[0075] As described above, in this embodiment, the position of the pickup roller 21 is detected by the contact / separation sensor 132 detecting the detection flag 24, and a new feed roller unit 20 is detected when the right door 115 is opened or closed. By detecting the state of the detection flag 24 when detecting a new feed roller unit 20, it is possible to automatically detect replacement of the feed roller unit 20 with a new one without increasing costs by using only one sensor. Furthermore, movement of the detection flag 24 of the feed roller unit 20 from the retracted position to the protruding position is achieved in the narrow space inside the feed roller unit 20 by using the protrusion 24a that interferes with the rubber material of the pickup roller 21 and the state-maintaining spring 29.

[0076] In this embodiment, the switching drive unit 170 controls the contact / separation arm 133 using a cam (not shown), but it is also possible to control the position by controlling, for example, a rack gear connected to the lift-up drive unit 70 of the first embodiment. The sheet feeding device 10 of this embodiment may include both the lift-up drive unit 70 of the first embodiment and the switching drive unit 170 of this embodiment. Furthermore, in the first and second embodiments, the sheet feeding device 10 provided in a laser beam printer is exemplified, but the image forming apparatus to which the present invention is applied is not limited to this, and may be, for example, a printer or copier using another printing method, such as an inkjet printer.

[0077] As described above, according to this embodiment, it is possible to automatically detect that the feeding roller has been replaced with a new one. [Explanation of symbols]

[0078] 20 Feeding roller unit 21 Pickup roller 23 Roller holder 24 Detection Flag 30 Feeding roller holding unit 32 Paper surface sensor 52 Loading plate 70 Lift-up drive unit 80 Control Unit

Claims

1. a loading section having a loading plate on which sheets are loaded and which can be raised and lowered; a feeding unit including a feeding roller for feeding a sheet, a rotatable support portion for supporting the feeding roller, and a detection member provided on the support portion; a holding unit having a detection means for detecting the detected member, the holding unit being disposed above the stacking section, and detachably holding the feeding unit; a drive unit that moves the loading plate up and down; a control unit that controls the drive unit to rotate the stacking plate so as to lift the stacking plate, and sets the sheets stacked on the stacking plate to a state where they can be fed based on the detection result of the detection member by the detection unit; Equipped with When the feeding unit is new, the detected member is located at a first position where it cannot be detected by the detecting means, and when the new feeding unit is attached to the holding unit and the feeding roller is driven, the detected member moves from the first position to a second position where it protrudes so that it can be detected by the detecting means; The control means controls the drive unit to raise and lower the stacking plate so that the sheet on the stacking plate is set in a state where it can be fed when the feeding unit is installed, and determines whether the feeding unit is new based on the detection result of the detection means.

2. 2. The sheet feeding apparatus according to claim 1, wherein the control means determines that the feeding unit is not new when the detection means detects the detection target member.

3. The sheet feeding device according to claim 2, characterized in that, when the detection means does not detect the detectable member and the detection means detects the detectable member after driving the feed roller, the control means determines that the feed unit is new, and when the detection means does not detect the detectable member, the control means determines that the feed unit is not installed.

4. 4. The sheet feeding device according to claim 3, wherein the control unit controls the drive unit to lower the stacking plate from a position where the sheets stacked on the stacking plate can be fed, and then drives the feeding roller.

5. a loading section having a loading plate on which sheets are loaded; a feeding unit including a feeding roller for feeding a sheet, a rotatable support portion for supporting the feeding roller, and a detection member provided on the support portion; a holding unit that is disposed above the stacking section and detachably holds the feeding unit, the holding unit having: a detecting means that detects a contact / separation state between the sheets stacked on the stacking plate and the feeding roller based on the detection state of the detected member; and a switching means that changes the state of the feeding unit by raising and lowering the feeding unit so that the sheets stacked on the stacking plate and the feeding roller are in contact or separated; a control means for controlling the switching means to lower the feeding unit and setting the sheet on the stacking plate to a state where the sheet can be fed based on the detection result of the detection means; Equipped with When the feeding unit is new, the detected member is located at a first position where it cannot be detected by the detecting means, and when the new feeding unit is attached to the holding unit and the feeding roller is driven, the detected member moves from the first position to a second position where it protrudes so that it can be detected by the detecting means; A sheet feeding device characterized in that, when the feeding unit is installed, the control means determines whether the feeding unit is new based on the detection result of the detection means when the feeding unit is installed.

6. 6. The sheet feeding apparatus according to claim 5, wherein the control means determines that the feeding unit is not new when the detection means detects the detection target member.

7. The sheet feeding device according to claim 6, characterized in that when the detection means does not detect the detectable member and the detection means detects the detectable member after driving the feed roller, the control means determines that the feed unit is new, and when the detection means does not detect the detectable member, the control means determines that the feed unit is not installed.

8. 8. The sheet feeding device according to claim 7, wherein when the feeding unit is attached to the holding unit, the feeding roller is spaced apart from the sheets stacked on the stacking plate.

9. the detected member has a protrusion that interferes with the feed roller when the detected member is located at the first position, A sheet feeding device as described in any one of claims 1 to 8, characterized in that when the feed roller is driven, the convex portion interfering with the feed roller moves so as to protrude toward the detection means, thereby moving the detected member from the first position to the second position.

10. the feeding unit has a pressing portion that presses the detection member, the detected member has a first inclined surface that is pressed by the pressing portion when the detected member is located at the first position, via a peak portion that protrudes toward the pressing portion, and a second inclined surface that is pressed by the pressing portion when the detected member is located at the second position, The sheet feeding device according to claim 9, characterized in that, when the feeding roller is driven, the convex portion interferes with the feeding roller at the peak portion where the detected member pressed by the pressing portion switches from the first inclined surface to the second inclined surface.

11. The sheet feeding device according to claim 9 or claim 10, characterized in that the holding unit has a stop portion against which the detected member hits when the detected member moves to the second position, preventing the detected member from moving in the direction of the detection means.

12. an image forming means for forming an image on a sheet; a sheet feeding device according to any one of claims 1 to 11; An image forming apparatus comprising:

13. an image forming means for forming an image on a sheet; a sheet feeding device according to any one of claims 1 to 11; a door that is opened and closed when replacing the feeding unit; an open / close detection means for detecting the open / close state of the door; Equipped with The image forming apparatus is characterized in that the control means determines that the feeding unit has been installed when the open / close detection means detects a change in the state of the door from an open state to a closed state.

14. an image forming means for forming an image on a sheet; a sheet feeding device according to claim 3 or claim 7; a display unit that displays information; Equipped with The image forming apparatus is characterized in that, when the detecting means does not detect the detected member, the control means displays on the display unit that the feeding unit is not installed.

Images