Sheet feeder, and image forming device

Abstract

To provide a sheet feeder capable of adjusting a feeding pressure with a simple configuration at a low cost, and an image forming device comprising the same.SOLUTION: A sheet feeder comprises: a feed roller unit comprising a loading part capable of loading a sheet, a feed roller, and a holding member for holding the feed roller in a swingable manner; a first energization member for energizing the holding member in such a manner that the feed roller presses the sheet; and an attachable / detachable unit provided with a second energization member for energizing the holding member, the attachable / detachable unit supported in an attachable / detachable manner by at least one of the feed roller unit and a device body. A feeding pressure made to act on the sheet when the feed roller feeds the sheet loaded on the loading part becomes a first feeding pressure with the first energization member and the second energization member in a state where a feeding pressure adjustment mechanism is attached thereto, and becomes a second feeding pressure different from the first feeding pressure with the first energization member in a state where the feeding pressure adjustment mechanism is detached therefrom.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a sheet feeding device for feeding a sheet and an image forming apparatus including the same.

Background Art

[0002] Conventionally, a printing machine has been proposed that includes a feed pressure adjustment mechanism capable of changing the feed pressure when feeding a sheet by a feed roller (see Patent Document 1). The feed roller is held by a feed arm so as to be movable up and down. The feed pressure adjustment mechanism includes a pressure arm that presses the feed arm, a pressure spring that biases the pressure arm, a rack that changes the biasing force of the pressure spring, and a feed pressure variable motor that drives the rack.

[0003] Also, a feeding device has been proposed that includes a pickup roll, a roll support that supports the pickup roll so as to be movable up and down, a sliding member that is movable in a horizontal direction with respect to the roll support, and a weight provided at an end of the sliding member (see Patent Document 2). The sliding member is moved by a gear driven by a motor, and the distance between the weight and the pickup roll changes as the sliding member moves, and as a result, the feed pressure changes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in both Patent Documents 1 and 2, the configuration is such that the feed pressure is variable by a motor. For example, for a user who only uses a specific type of sheet and does not need to adjust the feed pressure, the device is complicated and a factor in cost increase.

[0006] Therefore, an object of the present invention is to provide a sheet feeding device capable of adjusting a feeding pressure with a simple configuration and at low cost, and an image forming apparatus including the same.

Means for Solving the Problems

[0007] The present invention relates to a sheet feeding device, comprising: a device main body; a stacking unit supported by the device main body and capable of stacking sheets; a feeding roller for feeding the sheets stacked on the stacking unit; a holding member for swingably holding the feeding roller; a feeding roller unit having the holding member; a first biasing member for biasing the holding member so that the feeding roller presses the sheets stacked on the stacking unit; and a detachable unit detachably supported by at least one of the feeding roller unit and the device main body, the detachable unit having a second biasing member for biasing the holding member. When the feeding roller feeds the sheets stacked on the stacking unit, the feeding pressure applied to the sheets is a first feeding pressure by the first biasing member and the second biasing member when the detachable unit is mounted, and is a second feeding pressure different from the first feeding pressure by the first biasing member when the detachable unit is removed.

[0008] Further, the present invention relates to a sheet feeding device, comprising: a device main body; a stacking unit supported by the device main body and capable of stacking sheets; a feeding roller unit including a feeding roller for feeding the sheets stacked on the stacking unit; and a detachable unit capable of adjusting the feeding pressure applied to the sheets when the feeding roller feeds the sheets stacked on the stacking unit. The detachable unit is detachably supported by at least one of the feeding roller unit and the device main body, and the feeding pressure is a first feeding pressure when the detachable unit is mounted, and is a second feeding pressure different from the first feeding pressure when the detachable unit is removed.

[0009] Further, the present invention provides a sheet feeding device, comprising: a device main body; a stacking part supported by the device main body and capable of stacking sheets; a feeding roller for feeding the sheets stacked on the stacking part; a holding member for swingably holding the feeding roller; a feeding roller unit having the above components; and a first biasing member for biasing the holding member so that the feeding roller presses the sheets stacked on the stacking part. At least one of the feeding roller unit and the device main body is provided with a support part for detachably supporting a detachable unit having a second biasing member for biasing the holding member. The support part abuts against the second biasing member when the detachable unit is mounted. When the feeding roller feeds the sheets stacked on the stacking part, the feeding pressure acting on the sheets is a first feeding pressure by the first biasing member and the second biasing member when the detachable unit is mounted, and is a second feeding pressure different from the first feeding pressure by the first biasing member when the detachable unit is removed.

Advantages of the Invention

[0010] According to the present invention, the feeding pressure can be adjusted with a simple structure and low cost.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0012] <First Embodiment> 〔Overall Configuration〕 First, a first embodiment of the present invention will be described. As shown in FIG. 1, the image forming apparatus 1 of the present embodiment is a laser beam printer using an electrophotographic method for forming a monochrome toner image. As shown in FIG. 1, the image forming apparatus 1 includes a sheet feeding device 100 that feeds the loaded sheets, and an image forming unit 50 that forms an image on the fed sheets. Further, the image forming apparatus 1 includes a fixing device 6 that fixes the image transferred to the sheet, and a pair of discharge rollers 8 that can discharge the sheet to a discharge tray 9.

[0013] Note that the image forming apparatus includes a printer, a copier, a facsimile machine, and a multifunction machine, and refers to a device that forms an image on a sheet used as a recording medium based on image information input from an external PC or image information read from a document. In addition, in addition to the main body having an image forming function, the image forming apparatus may be connected with accessory devices such as an optional feeder, an image reading device, and a sheet processing device. However, the entire system to which such accessory devices are connected is also a kind of image forming apparatus. Further, the sheet includes paper such as paper and envelopes, plastic films such as overhead projector sheets (OHP), and cloth. The sheet feeding device 100 described later includes an optional feeder independent of the image forming apparatus 1.

[0014] When a command for image formation is output to the image forming apparatus 1, an image forming process by the image forming unit 50 is started based on the image information input from an external computer or the like connected to the image forming apparatus 1. The image forming unit 50 includes a process cartridge 55, a laser scanner 53, and a transfer roller 52. The process cartridge 55 includes a photosensitive drum 51 that can rotate while carrying a toner image, and a charging roller, a developing roller, and a cleaning blade (not shown) arranged along the photosensitive drum 51. The process cartridge 55 is detachable from the apparatus main body 1A of the image forming apparatus 1.

[0015] The laser scanner 53 irradiates the photosensitive drum 51 with laser light based on the input image information. At this time, the photosensitive drum 51 is pre-charged by a charging roller, and an electrostatic latent image is formed on the photosensitive drum 51 when irradiated with the laser light. Then, this electrostatic latent image is developed by a developing roller, and a monochrome toner image is formed on the photosensitive drum 51.

[0016] In parallel with the above-described image forming process, the sheet S is fed from the sheet feeding device 100. The sheet feeding device 100 has a cassette 30 that is supported so as to be pullable in the pulling direction DD with respect to the apparatus main body 1A, and the cassette 30 as a loading unit is configured to be able to load the sheet S. The sheet S accommodated in the cassette 30 is fed by a pickup roller 12, and the sheet S fed by the pickup roller 12 is separated one by one by a feed roller 13 and a separation roller 36 that presses against the feed roller 13. The separation roller 36 is biased toward the feed roller 13 by a separation spring 37 (see FIG. 6(c)).

[0017] The separation roller 36 incorporates a torque limiter. When one sheet is conveyed to the separation nip formed by the feed roller 13 and the separation roller 36, the limit value of the torque limiter is set so that the separation roller 36 rotates in a driven manner with respect to the feed roller 13. When a plurality of sheets are conveyed to the separation nip, the separation roller 36 stops without rotating in a driven manner with respect to the feed roller 13. Note that a drive may be input to the separation roller 36 so as to convey the sheet in a direction opposite to the sheet conveyance direction by the feed roller 13. In the present embodiment, only one-stage cassette 30 is provided, but a plurality of cassettes capable of supporting sheets of different sizes may be provided, and the sheets may be fed in accordance with the sheet size selected from these plurality of cassettes.

[0018] The sheets S separated one by one by the feed roller 13 and the separation roller 36 are conveyed to the registration roller pair 42 by the conveying roller pair 41, and the skew is corrected by the registration roller pair 42. The leading edge of the sheet S conveyed at a predetermined conveying timing by the registration roller pair 42 is detected by the registration sensor 45. Based on the fact that the registration sensor 45 has detected the leading edge of the sheet S, the image forming unit 50 starts forming a toner image on the photosensitive drum 51. Then, the toner image on the photosensitive drum 51 is transferred onto the sheet S by the electrostatic negative bias applied to the transfer roller 52. The residual toner remaining on the photosensitive drum 51 is collected by the cleaning blade.

[0019] The sheet S onto which the toner image has been transferred is given a predetermined heat and pressure by the heating roller and the pressure roller of the fixing device 6, and the toner is melted and fixed (fixed). The sheet S that has passed through the fixing device 6 is conveyed to the discharge roller pair 8 by the conveying roller pair 46, and is discharged to the discharge tray 9 by the discharge roller pair 8.

[0020] [Overview of the Sheet Feeding Device] Next, the overview of the sheet feeding device 100 will be described. FIG. 2 is a perspective view showing the cassette 30 and the feed roller unit 10. FIG. 3(a) is a perspective view showing the feed unit 20, and FIG. 3(b) is a perspective view showing a state in which the feed roller unit 10 is removed from the roller support unit 40 of the feed unit 20. In FIG. 2, the roller support unit 40 is omitted.

[0021] As shown in FIGS. 2 to 3(b), the sheet feeding device 100 includes a part of the device main body 1A, a feed unit 20, a motor M for supplying a driving force to the feed unit 20, and a cassette 30. The feed unit 20 includes a roller support unit 40, a feed roller unit 10, a swing mechanism 80 for swinging the feed roller unit 10, and a feed pressure adjustment mechanism 70 as a detachable unit detachably supported by the feed roller unit 10.

[0022] [Cassette] Next, the configuration of the cassette 30 will be described with reference to FIG. 2. As shown in FIG. 2, the cassette 30 includes a cassette body 31, a middle plate 32 that is rotatably supported by the cassette body 31 and serves as a loading member on which the sheet S is loaded, a lifter plate 34, and a lifter drive train 33 that drives the lifter plate 34. The cassette 30 also has a rear end regulating member 76 that regulates the position of the upstream end of the sheet S loaded on the middle plate 32 in the sheet feeding direction FD. The rear end regulating member 76 is supported by the cassette body 31 so as to be movable in the direction along the sheet feeding direction FD.

[0023] The lifter drive train 33 includes a first gear 33a driven by a motor (not shown), a lifter gear 33c provided integrally with the lifter plate 34, and a second gear 33b that meshes with the first gear 33a and the lifter gear 33c and is rotatably supported by the cassette body 31. The first gear 33a is driven by the motor, for example, when a print job is input to the image forming apparatus 1 or when the cassette 30 is mounted on the apparatus main body 1A. The rotation of the first gear 33a is transmitted to the lifter gear 33c via the second gear 33b, and the lifter plate 34 integrated with the lifter gear 33c rotates. As a result, the middle plate 32 is pressed from below by the lifter plate 34, and the middle plate 32 rises (rotates).

[0024] In this embodiment, an envelope placement table 75 as an attachment member is detachably supported on the upper surface 32a of the middle plate 32. The envelope placement table 75 is disposed at the center in the sheet width direction W orthogonal to the sheet feeding direction FD of the middle plate 32 and is arranged to overlap the pickup roller 12 in the sheet width direction W. For example, an envelope can be placed on the envelope placement table 75, and in the sheet width direction W, the width of the envelope placement table 75 is smaller than the width of the envelope to be placed. Therefore, the envelope placement table 75 can support the envelope as a sheet so as to be swingable in the sheet width direction W.

[0025] As a result, even if the envelopes stacked on the envelope placement table 75 are stored in the cassette 30 in a state where the height of the bundle is unbalanced in the width direction (left - right direction) due to curling or overlapping of the flaps, they swing in the sheet width direction W by the envelope placement table 75. Thereby, the top - most envelope in the bundle assumes a posture along the substantially horizontal direction. For this reason, the pickup roller 12 can apply a feeding pressure evenly to the envelopes stored in the cassette 30, and feeding defects such as skewing of the envelopes can be reduced.

[0026] [Feeding Unit] Next, the configuration of the feeding unit 20 will be described with reference to FIGS. 3(a) to 5(b). FIG. 4(a) is a perspective view showing the feeding roller unit 10 and the feeding pressure adjustment mechanism 70, and FIG. 4(b) is another perspective view showing the feeding roller unit 10 and the feeding pressure adjustment mechanism 70. FIG. 4(c) is an exploded perspective view showing the feeding roller unit 10 and the feeding pressure adjustment mechanism 70.

[0027] As shown in FIGS. 3(a) and 3(b), the feeding unit 20 includes a roller support unit 40 supported by the apparatus main body 1A, a feeding roller unit 10 detachably supported by the roller support unit 40, and a swing mechanism 80. The roller support unit 40 includes a feed shaft 21, a slide shaft 22, a feed bearing 23, and a slide spring 24.

[0028] The feed shaft 21 and the slide shaft 22 are supported by the apparatus main body 1A and extend in the sheet width direction W. A coupling portion 21b is provided at one end of the feed shaft 21 in the sheet width direction W, and the coupling portion 21b transmits rotation to the feed roller 13 of the feeding roller unit 10. The slide shaft 22 is slidable in the sheet width direction W and is biased in the direction of arrow P within the sheet width direction W by the slide spring 24.

[0029] As shown in FIGS. 4(a) to 4(c), the feed roller unit 10 has a roller holder 11, a pickup roller 12, a feed roller 13, and an idler gear 14. The roller holder 11 as a holding member rotatably supports the pickup roller 12, the feed roller 13, and the idler gear 14, respectively. Gear portions 12a and 13a are provided at one ends of the pickup roller 12 and the feed roller 13, respectively, and the idler gear 14 meshes with these gear portions 12a and 13a. Further, a coupling hole 13b is provided at the axial center portion of the feed roller 13.

[0030] The roller holder 11 has a boss 11a extending upstream in the sheet feed direction FD in a state where the feed roller unit 10 is mounted on the roller support unit 40, and a bearing portion 11b engageable with the slide shaft 22. The bearing portion 11b is provided on one end side of the feed roller 13 in the sheet width direction W.

[0031] In a state where the feed roller unit 10 is mounted on the roller support unit 40 as shown in FIG. 3(a), the coupling portion 21b of the feed shaft 21 engages with the coupling hole 13b (see FIG. 4(b)) of the feed roller 13. Thus, when the feed shaft 21 rotates by the driving force of the motor M, the rotation of the feed shaft 21 is transmitted to the feed roller 13 via the coupling portion 21b and the coupling hole 13b. Further, the rotation of the feed roller 13 is transmitted to the pickup roller 12 as a feed roller via the gear portion 13a, the idler gear 14, and the gear portion 12a.

[0032] Further, the slide shaft 22 engages with the bearing portion 11b of the roller holder 11, and the feed roller unit 10 is supported by the feed shaft 21 and the slide shaft 22. At this time, the slide shaft 22 is provided with ribs (not shown) for controlling the posture of the feed roller unit 10. In a state where the feed roller unit 10 is supported by the roller support unit 40, the rotation axes of the feed shaft 21, the slide shaft 22, and the feed roller 13 are coaxial. The attachment and detachment operation of the feed roller unit 10 with respect to the roller support unit 40 will be described later.

[0033] Next, the swing mechanism 80 will be described with reference to FIGS. 3(a) to 5(b). FIG. 5(a) is a perspective view showing the arm unit 15 of the swing mechanism 80, and FIG. 5(b) is another perspective view showing the arm unit 15. As shown in FIGS. 3(a) and 3(b), the swing mechanism 80 includes an arm unit 15, a first feed pressure spring 16, a separation arm 25, and a separation spring 26. The arm unit 15 and the separation arm 25 are each independently provided so as to be rotatable about a rotation fulcrum Q.

[0034] The arm unit 15 as a swing portion includes an arm 17, a cap 18, and a cap spring 19 as shown in FIGS. 5(a) and 5(b). The arm 17 is supported so as to be rotatable with respect to the apparatus main body 1A about the rotation fulcrum Q. Further, the arm 17 has a spring mounting portion 17a to which the first feed pressure spring 16 (see FIG. 3(a)) is attached.

[0035] The cap 18 is supported so as to be movable in the direction of arrow U or in the direction opposite to the direction of arrow U with respect to the arm 17, and is disposed on the side opposite to the spring mounting portion 17a with the rotation fulcrum Q interposed therebetween. The cap spring 19 is disposed between the arm 17 and the cap 18, and biases the cap 18 in the direction of arrow U. The cap 18 as a contact portion is provided with a concave portion 18a, an engaging portion 18b, and a tapered portion 18c. In a state where the feed roller unit 10 is attached to the roller support unit 40 and the cassette 30 is removed from the apparatus main body 1A, the boss 11a (see FIG. 4(a)) of the roller holder 11 engages with the engaging portion 18b.

[0036] Also, as shown in FIGS. 3(a) and 3(b), the separation arm 25 is provided with a cassette contact portion 25a that can contact the cassette 30 and an arm engagement portion 25b that can engage with the arm unit 15. The separation spring 26 biases the separation arm 25 in the direction of arrow R (downward), and the movement of the separation spring 26 in the direction of arrow R is restricted by abutting against a stopper (not shown). On the other hand, the first feed pressure spring 16 biases the arm unit 15 in the direction of arrow V (upward). The direction of arrow R and the direction of arrow V are opposite to each other, and the biasing force of the separation spring 26 is set to be greater than the biasing force of the first feed pressure spring 16.

[0037] In this embodiment, the first feed pressure spring 16 and the separation spring 26 are each composed of a compression coil spring, but the present invention is not limited to this. For example, the first feed pressure spring 16 and the separation spring 26 may be biasing members such as a leaf spring, a torsion bar, a rubber member, or a sponge.

[0038] [Feed Pressure Adjusting Mechanism] Next, the feed pressure adjusting mechanism 70 will be described with reference to FIGS. 4(a) to 4(c). As shown in FIGS. 4(a) to 4(c), the feed pressure adjusting mechanism 70 includes a second feed pressure spring 71 and a spring holder 72. The spring holder 72 as the first contact member has bearing portions 72b, 72e, a boss 72c, and an abutting portion 72a. The bearing portions 72b, 72e are rotatably supported by the bearing portions 11b, 11e of the roller holder 11. These bearing portions 72b, 72e and the bearing portions 11b, 11e are arranged on opposite sides of each other with the feed roller 13 interposed therebetween. The abutting portion 72a can abut against the abutting portion 20a provided on the apparatus main body 1A.

[0039] Further, a top surface boss 11c as a support portion is provided on the top surface 11d of the roller holder 11. Then, with the spring holder 72 attached to the roller holder 11, a second feed pressure spring 71 is attached to each of the boss 72c of the spring holder 72 and the top surface boss 11c of the roller holder 11. That is, the top surface boss 11c abuts against the second feed pressure spring 71 in a state where the feed pressure adjusting mechanism 70 is mounted on the feed roller unit 10. Further, a groove 72f is provided in the bearing portion 72b of the spring holder 72, and the spring holder 72 is restricted in its rotation range with respect to the roller holder 11 by the engagement of a rib (not shown) provided on the roller holder 11 with the groove 72f. Thereby, the second feed pressure spring 71 provided between the roller holder 11 and the spring holder 72 is configured not to fall off from the roller holder 11 and the spring holder 72. The second feed pressure spring 71 is disposed at a position shifted in plan view from the feed shaft 21 and the slide shaft 22 which are the rotation centers of the roller holder 11, and biases the roller holder 11.

[0040] Note that, in the present embodiment, the second feed pressure spring 71 as the second biasing member is composed of a compression coil spring, but is not limited thereto. For example, the second feed pressure spring 71 may be an elastic member such as a leaf spring, a torsion bar, a rubber member, or a sponge.

[0041] [Actions of the swing mechanism and the feed pressure adjusting mechanism] Next, with reference to FIGS. 6(a) to 6(c), the actions of the swing mechanism 80 and the feed pressure adjusting mechanism 70 will be described. FIG. 6(a) is a side view showing the feed roller unit 10 and the feed pressure adjusting mechanism 70 in a state where the cassette 30 is removed from the apparatus main body 1A. FIG. 6(b) is a side view showing the feed roller unit 10 and the feed pressure adjusting mechanism 70 in a state where the cassette 30 is mounted on the apparatus main body 1A. FIG. 6(c) is a side view showing the feed roller unit 10 and the feed pressure adjusting mechanism 70 when the middle plate 32 is lifted from the state of FIG. 6(b).

[0042] The following description is based on the premise that the feeding roller unit 10 is attached to the roller support unit 40. As shown in Fig. 6(a), when the cassette 30 is removed from the apparatus main body 1A, the cassette contact portion 25a of the separation arm 25 shown in Fig. 3(a) separates from the cassette 30. For this reason, the separation arm 25 rotates about the rotation fulcrum Q by the biasing force of the separation spring 26 in the direction of arrow R. As a result, the arm engagement portion 25b provided on the separation arm 25 presses the arm unit 15 downward. At this time, since the biasing force of the first feeding pressure spring 16 is weaker than the biasing force of the separation spring 26, the arm unit 15 rotates about the rotation fulcrum Q in the direction of arrow R, that is, in the direction opposite to the direction of arrow V.

[0043] As a result, the engagement portion 18b (see Fig. 5(a)) of the cap 18 provided at the end of the arm unit 15 pushes up the boss 11a of the roller holder 11. For this reason, the feeding roller unit 10 including the roller holder 11 rotates in the direction of arrow T about the feed shaft 21 and the slide shaft 22. That is, when the cassette 30 is pulled out from the apparatus main body 1A, the pickup roller 12 is lifted by the swing mechanism 80. For example, the pickup roller 12 moves from the second position shown by the broken line in Fig. 6(a) to the first position shown by the solid line in Fig. 6(a).

[0044] The ascent of the pickup roller 12 as described above starts at the initial stage when the cassette 30 starts to be pulled out from the apparatus main body 1A. This is realized by the cam shape of the cassette body 31 that contacts the cassette contact portion 25a. Thereby, the catching between the pickup roller 12 and the sheet S on the middle plate 32 can be suppressed, and the attachability / detachability of the cassette 30 can be improved.

[0045] Then, as shown in FIGS. 3(a) and 6(b), when the cassette 30 is mounted on the apparatus main body 1A, the cassette contact portion 25a is pushed up against the biasing force of the separation spring 26 by the cam shape of the cassette main body 31. As a result, the arm engagement portion 25b provided on the separation arm 25 also rises. Since the arm unit 15 was pressed against the arm engagement portion 25b by the biasing force of the first feed pressure spring 16, it rotates in the direction of arrow V about the rotation fulcrum Q together with the separation arm 25.

[0046] Then, the recess 18a (see FIG. 5(a)) of the cap 18 provided at the end of the arm unit 15 pushes down the boss 11a of the roller holder 11. For this reason, the feed roller unit 10 including the roller holder 11 rotates in the direction opposite to the direction of arrow T about the feed shaft 21 and the slide shaft 22. That is, when the cassette 30 is mounted on the apparatus main body 1A, the pickup roller 12 is lowered from the first position shown by the solid line in FIG. 6(a) to the second position shown by the broken line in FIG. 6(a) by the swing mechanism 80. This is because the first feed pressure spring 16 biases the pickup roller 12 toward the second position via the arm unit 15.

[0047] At this time, the abutting portion 72a provided on the top surface of the spring holder 72 of the feed pressure adjustment mechanism 70 provided on the feed roller unit 10 is in contact with the contact portion 20a provided on the apparatus main body 1A. Further, the pickup roller 12 located at the second position is not in contact with the sheet S stacked on the middle plate 32.

[0048] Thereafter, as shown in FIG. 6(c), when the intermediate plate 32 ascends, the uppermost sheet S loaded on the intermediate plate 32 comes into contact with the pickup roller 12. Then, as the intermediate plate 32 ascends by a predetermined amount, the pickup roller 12 ascends from the second position to the third position shown in FIG. 6(c) by the sheet S loaded on the intermediate plate 32. As the pickup roller 12 ascends, the feed roller unit 10 ascends in the direction of arrow T shown in FIG. 3(a) about the feed shaft 21 and the slide shaft 22. Thereby, the boss 11a of the roller holder 11 pushes up the arm unit 15. That is, the arm unit 15 rotates in the direction of arrow R about the rotation fulcrum Q. When the pickup roller 12 ascends from the second position to the third position, the concave portion 18a of the cap 18 of the arm unit 15 and the boss 11a maintain the engaged state. By providing the concave portion 18a in the cap 18, the holding force of the boss 11a by the arm unit 15 can be improved.

[0049] As the arm unit 15 rotates in the direction of arrow R about the rotation fulcrum Q, the arm unit 15 separates from the arm engagement portion 25b of the separation arm 25. Therefore, the biasing force of the first feed pressure spring 16 acts to increase the feed pressure of the pickup roller 12 via the arm unit 15 and the roller holder 11. In other words, the first feed pressure spring 16 as the first biasing member biases the roller holder 11 so that the pickup roller 12 presses the sheet S loaded in the cassette 30.

[0050] Also, as the pickup roller 12 ascends to the third position, as shown in FIG. 6(c), the second feed pressure spring 71 between the roller holder 11 and the spring holder 72 is compressed. Then, the roller holder 11 receives an elastic force from the second feed pressure spring 71, and the elastic force acts to increase the feed pressure of the pickup roller 12.

[0051] That is, when the pickup roller 12 feeds the sheet S, the feeding pressure applied to the sheet S is the first feeding pressure N1 by the first feeding pressure spring 16 and the second feeding pressure spring 71 in the state where the feeding pressure adjusting mechanism 70 is attached to the feeding roller unit 10. The first feeding pressure N1 is the sum of the biasing force received by the pickup roller 12 from the first feeding pressure spring 16 and the elastic force received by the pickup roller 12 from the second feeding pressure spring 71.

[0052] Thereafter, as shown in FIG. 3(a), when the motor M is driven, the feed roller 13 and the pickup roller 12 rotate, and the sheet S is fed by the pickup roller 12. Thereafter, as described above, the toner image is transferred to the sheet S and discharged to the discharge tray 9. [Detachment and attachment of the feeding roller unit with respect to the roller support unit]

[0053] Next, with reference to FIGS. 7(a) to 7(c), the detachment and attachment of the feeding roller unit 10 with respect to the roller support unit 40 will be described. FIG. 7(a) is a perspective view showing a state where the feeding roller unit 10 is attached to the roller support unit 40 and a cross-sectional view showing the boss 11a and the cap 18 at that time. FIG. 7(b) is a perspective view showing a state where the engagement between the feeding roller unit 10 and the roller support unit 40 is released and a cross-sectional view showing the boss 11a and the cap 18 at that time. FIG. 7(c) is a perspective view showing a state where the feeding roller unit 10 is removed downward from the roller support unit 40 and a cross-sectional view showing the boss 11a and the cap 18 at that time.

[0054] When an operator such as a user or a service technician removes the feeding roller unit 10 from the roller support unit 40, first, as shown in FIG. 1, the cassette 30 is pulled out in the pulling-out direction DD from the apparatus main body 1A. The apparatus main body 1A has an opening 90 through which the cassette 30 passes when the cassette 30 is attached to and detached from the apparatus main body 1A. Then, the cassette 30 is removed from the apparatus main body 1A through the opening 90.

[0055] Then, as shown in FIG. 7(a), the feed roller unit 10 is exposed through the opening 90. That is, the operator can access the feed roller unit 10 through the opening 90. Also, when the feed pressure adjusting mechanism 70 is attached to the feed roller unit 10, the operator can access the feed pressure adjusting mechanism 70 through the opening 90.

[0056] At this time, the boss 11a provided on the roller holder 11 is engaged with the engaging portion 18b provided on the cap 18 of the arm unit 15. This is because, as described above, when the cassette 30 is removed from the apparatus main body 1A, the arm unit 15 is pushed down in the direction of arrow R (see FIG. 3(a)) by the arm engaging portion 25b of the separation arm 25.

[0057] Next, as shown in FIG. 7(b), the operator grips an arbitrary position of the feed roller unit 10 and slides the slide shaft 22 in the direction of the arrow (left direction) against the biasing force of the slide spring 24. At this time, the boss 11a provided on the roller holder 11 separates from the engaging portion 18b of the cap 18.

[0058] Thereafter, as shown in FIG. 7(c), the operator moves the feed roller unit 10 in the direction of the arrow (downward) in the left side view of FIG. 7(c). As a result, the feed roller unit 10 is removed from the feed shaft 21 and the slide shaft 22, and the boss 11a of the roller holder 11 is detached from the arm unit 15. Thus, the operator can remove the feed roller unit 10 from the roller support unit 40.

[0059] Incidentally, the procedure for attaching the feed roller unit 10 to the roller support unit 40 is the reverse of the procedure for detaching the feed roller unit 10 from the roller support unit 40. A taper portion 18c is provided on the cap 18 of the arm unit 15. When engaging the roller support unit 40 and the cap 18, the boss 11a presses the taper portion 18c. The taper portion 18c extends in a direction intersecting the biasing direction (the direction of arrow U shown in Fig. 5(a)) of the cap spring 19 of the cap 18. Therefore, when the boss 11a presses the taper portion 18c upward, the taper portion 18c slides in a direction opposite to the direction of arrow U against the biasing force of the cap spring 19. When the boss 11a gets over the taper portion 18c, the cap 18 slides in the direction of arrow U by the biasing force of the cap spring 19, and the boss 11a and the engaging portion 18b engage with each other as in the state of Fig. 7(a).

[0060] Also, in this embodiment, a feed pressure adjustment mechanism 70 is detachably supported by the feed roller unit 10. Therefore, when the feed pressure adjustment mechanism 70 is attached to the feed roller unit 10, the feed roller unit 10 and the feed pressure adjustment mechanism 70 can be removed from the roller support unit 40 simultaneously. Further, the feed pressure adjustment mechanism 70 does not hinder the attachment / detachment operation when the feed roller unit 10 is attached to or detached from the roller support unit 40.

[0061] [Adjustment of Feed Pressure] In this embodiment, it is possible to select whether to attach the feed pressure adjustment mechanism 70 to the feed roller unit 10 or remove it from the feed roller unit 10, whereby the feed pressure of the pickup roller 12 can be adjusted.

[0062] In particular, for a printing medium having a thickness or bulge like an envelope, by setting the feeding pressure of the pickup roller 12 higher compared to ordinary cut paper, feeding failures (non-feeding or skewing) can be suppressed. Specifically, when a large number of envelopes are loaded in the cassette 30 with the flaps of the envelopes aligned, the height of the stacked envelope bundle becomes non-uniform in the sheet width direction W depending on the thickness of the flap and the degree of folding of the flap. As a result, the topmost envelope of the envelope bundle may tilt with respect to the horizontal direction. Even in such a case, by setting the feeding pressure of the pickup roller 12 higher, the bulge of the envelope bundle can be flattened and the contact surface between the pickup roller 12 and the topmost envelope can be kept horizontal, suppressing feeding failures.

[0063] However, if ordinary cut paper is mainly used while maintaining a high feeding pressure setting as in the case of feeding envelopes, the wear of the pickup roller 12 becomes significant, reducing the lifespan of the pickup roller 12. Therefore, it is desirable that the feeding pressure of the pickup roller 12 can be easily changed according to the user's usage purpose.

[0064] As described with reference to FIG. 6(c), when the feeding pressure adjusting mechanism 70 is attached to the feeding roller unit 10, the feeding pressure of the pickup roller 12 becomes the first feeding pressure N1 by the first feeding pressure spring 16 and the second feeding pressure spring 71. For example, when using a sheet S such as an envelope instead of ordinary paper such as cut paper, by attaching the feeding pressure adjusting mechanism 70 to the feeding roller unit 10, feeding failures can be suppressed.

[0065] On the other hand, as shown in FIG. 8, when the feeding pressure adjusting mechanism 70 is removed from the feeding roller unit 10, it becomes the second feeding pressure N2 only by the first feeding pressure spring 16. The second feeding pressure N2 is different from the first feeding pressure N1, and more specifically, is lower than the first feeding pressure N1 (N2 < N1). For example, when using a sheet S such as cut paper instead of special paper such as an envelope, by removing the feeding pressure adjusting mechanism 70 from the feeding roller unit 10, the lifespan of the pickup roller 12 can be extended.

[0066] As described above, in this embodiment, by detaching the feed pressure adjusting mechanism 70 from the feed roller unit 10, the feed pressure can be adjusted with a simple configuration and at low cost. The feed pressure adjusting mechanism 70 does not have an actuator such as a motor or a solenoid, and has a simple and low-cost configuration.

[0067] The user can select either the first feed pressure N1 or the second feed pressure N2 according to the application, and can achieve both suppression of feeding failure and extension of the service life of the pickup roller 12. Further, for example, by selecting whether or not to attach the feed pressure adjusting mechanism 70 at the time of shipment according to the attributes of the user, the parts can be shared between the sheet feeding device with the feed pressure adjusting mechanism 70 attached and the sheet feeding device without the feed pressure adjusting mechanism 70 attached, and the cost can be reduced. Further, a user who mainly uses cut paper can reduce the cost and space of the sheet feeding device by using a sheet feeding device without the feed pressure adjusting mechanism 70 attached.

[0068] <Second Embodiment> Next, a second embodiment of the present invention will be described. The second embodiment is obtained by changing the feed pressure adjusting mechanism 70 of the first embodiment to a feed pressure adjusting mechanism 170. Therefore, for the same configuration as that of the first embodiment, illustration is omitted or the same reference numerals are given in the drawings and described.

[0069] FIG. 9(a) is a side view showing the feed roller unit 10 and the feed pressure adjusting mechanism 170 in a state where the cassette 30 is removed from the apparatus main body 1A according to the second embodiment. FIG. 9(b) is a side view showing the feed roller unit 10 and the feed pressure adjusting mechanism 170 in a state where the cassette 30 is mounted on the apparatus main body 1A. FIG. 9(c) is a side view showing the feed roller unit 10 and the feed pressure adjusting mechanism 170 when the middle plate 32 is raised from the state of FIG. 9(b).

[0070] As shown in FIGS. 9(a) to 9(c), the sheet feeding device 200 according to the second embodiment has a feeding pressure adjustment mechanism 170 as a detachable unit that is detachably supported by a spring engagement portion 120a provided on the device main body 1A.

[0071] The feeding pressure adjustment mechanism 170 has a second feeding pressure spring 171 detachably attached to the spring engagement portion 120a, and a contact member 172 as a second contact member attached to the second feeding pressure spring 171 and facing the top surface 11d of the roller holder 11. That is, the spring engagement portion 120a as a support portion contacts the second feeding pressure spring 171 in a state where the feeding pressure adjustment mechanism 170 is mounted on the device main body 1A.

[0072] In this embodiment, the second feeding pressure spring 171 is composed of a compression coil spring, but is not limited thereto. For example, the second feeding pressure spring 171 may be an elastic member such as a leaf spring, a torsion bar, a rubber member, or a sponge.

[0073] Also, in the swing mechanism 80 (see FIG. 3(a)) and the feeding roller unit 10 of this embodiment, they operate as shown in FIGS. 6(a) to 6(c) described in the first embodiment. Therefore, as shown in FIG. 9(a), when the cassette 30 is removed from the device main body 1A, the pickup roller 12 is located at the first position shown by the solid line. At this time, the contact member 172 of the feeding pressure adjustment mechanism 170 contacts the roller holder 11.

[0074] Also, as shown in FIG. 9(b), when the cassette 30 is mounted on the device main body 1A, the pickup roller 12 descends from the first position to the second position. At this time, the contact member 172 is separated from the roller holder 11.

[0075] Furthermore, as shown in FIG. 9(c), when the intermediate plate 32 rises, the pickup roller 12 rises from the second position to the third position by being pressed by the uppermost sheet S loaded on the intermediate plate 32. Then, the contact member 172 is pushed up by the roller holder 11, and the second feed pressure spring 171 between the contact member 172 and the spring engagement portion 120a is compressed. The roller holder 11 receives an elastic force from the second feed pressure spring 171 as the second biasing member, and this elastic force acts to increase the feed pressure of the pickup roller 12. Also, similar to the first embodiment, the biasing force of the first feed pressure spring 16 (see FIG. 3(a)) also acts to increase the feed pressure of the pickup roller 12 via the arm unit 15 and the roller holder 11.

[0076] That is, the feed pressure applied to the sheet S when the pickup roller 12 feeds the sheet S is the first feed pressure N1 by the first feed pressure spring 16 and the second feed pressure spring 171 in a state where the feed pressure adjusting mechanism 170 is attached to the apparatus main body 1A. The first feed pressure N1 is the sum of the biasing force received by the pickup roller 12 from the first feed pressure spring 16 and the elastic force received by the pickup roller 12 from the second feed pressure spring 171.

[0077] As described above, in the present embodiment, by detaching the feed pressure adjusting mechanism 170 from the apparatus main body 1A, the same effects as those of the first embodiment can be achieved. Also, although the feed pressure adjusting mechanism 170 is configured to be detachable from the apparatus main body 1A, different from the first embodiment, it may be detachably supported by at least one of the feed roller unit 10 and the apparatus main body 1A.

[0078] <Third Embodiment> Next, a third embodiment of the present invention will be described. The third embodiment is obtained by changing the feed pressure adjusting mechanism 70 of the first embodiment to a second feed pressure spring 271. Therefore, for the same configurations as those in the first embodiment, illustration is omitted or the same reference numerals are given in the drawings for explanation.

[0079] FIG. 10(a) is a side view showing the feeding roller unit 10 and the second feeding pressure spring 271 in a state where the cassette 30 is removed from the apparatus main body 1A according to the third embodiment. FIG. 10(b) is a side view showing the feeding roller unit 10 and the second feeding pressure spring 271 in a state where the cassette 30 is attached to the apparatus main body 1A. FIG. 10(c) is a side view showing the feeding roller unit 10 and the second feeding pressure spring 271 when the middle plate 32 rises from the state of FIG. 10(b).

[0080] As shown in FIGS. 10(a) to (c), the sheet feeding device 300 according to the third embodiment has a detachable unit and a second feeding pressure spring 271 as a second biasing member. The second feeding pressure spring 271 is detachably supported on a spring applying portion 220a provided on the apparatus main body 1A and a hook portion 11h provided on the roller holder 11, respectively. That is, the spring applying portion 220a and the hook portion 11h as support portions are in contact with the second feeding pressure spring 271 in a state where the second feeding pressure spring 271 is attached to the apparatus main body 1A and the feeding roller unit 10. In the present embodiment, the second feeding pressure spring 271 is composed of a tension spring which is an elastic member, but is not limited thereto. For example, a compression spring may be used instead of the tension spring. In this case, by attaching the second feeding pressure spring 271 to the spring applying portion 220a and the hook portion 11h, the feeding pressure increases.

[0081] Also, in the swing mechanism 80 (see FIG. 3(a)) and the feeding roller unit 10 of the present embodiment, they operate as shown in FIGS. 6(a) to (c) described in the first embodiment. Therefore, as shown in FIG. 10(a), when the cassette 30 is removed from the apparatus main body 1A, the pickup roller 12 is located at the first position shown by the solid line. Further, as shown in FIG. 10(b), when the cassette 30 is attached to the apparatus main body 1A, the pickup roller 12 descends from the first position to the second position.

[0082] Further, as shown in FIG. 10(c), when the intermediate plate 32 rises, the pickup roller 12 rises from the second position to the third position by being pressed by the uppermost sheet S loaded on the intermediate plate 32. Then, the second feed pressure spring 271 is compressed more than in the state shown in FIG. 10(b).

[0083] In the present embodiment, since the second feed pressure spring 271 is composed of a tension spring, the second feed pressure spring 271 has the effect of reducing the feed pressure of the pickup roller 12. Also, similar to the first embodiment, the biasing force of the first feed pressure spring 16 (see FIG. 3(a)) acts to increase the feed pressure of the pickup roller 12 via the arm unit 15 and the roller holder 11.

[0084] That is, the feed pressure applied to the sheet S when the pickup roller 12 feeds the sheet S is the first feed pressure N3 by the first feed pressure spring 16 and the second feed pressure spring 271 when the second feed pressure spring 271 is mounted on the apparatus main body 1A and the feed roller unit 10. The first feed pressure N3 is the sum of the biasing force received by the pickup roller 12 from the first feed pressure spring 16 and the elastic force (negative value) received by the pickup roller 12 by the second feed pressure spring 271. Also, the biasing force of the first feed pressure spring 16 is greater than the elastic force of the second feed pressure spring 271.

[0085] As described above, since the first feed pressure N3 has the effect of reducing the feed pressure, when the second feed pressure spring 271 is removed from the apparatus main body 1A and the feed roller unit 10, that is, when the feed pressure in the state shown in FIG. 8 is the second feed pressure N2, the first feed pressure N3 is smaller than the second feed pressure N2.

[0086] As described above, in the present embodiment, by attaching and detaching the second feed pressure spring 271 to and from the apparatus main body 1A and the feed roller unit 10, the feed pressure of the pickup roller 12 can be adjusted with a simple configuration and low cost.

[0087] In general, the higher the feeding pressure of the pickup roller 12, the more likely the double feeding phenomenon due to poor sheet separation will occur. In particular, in a case where it is used in a harsh environment such as a high humidity environment, there are situations where the double feeding phenomenon is more likely to occur. When feeding sheets in such a harsh environment or sheets of a type that are prone to double feeding, it is possible to adjust the feeding pressure to be lowered simply by attaching the second feeding pressure spring 271 as in the present embodiment. As a result, it is possible to easily prevent the double feeding phenomenon even when feeding sheets in a harsh environment or sheets of a type that are prone to double feeding.

[0088] <Fourth Embodiment> Next, a fourth embodiment of the present invention will be described. The fourth embodiment is obtained by changing the feeding pressure adjusting mechanism 70 of the first embodiment to a weight member 371. Therefore, for the same configuration as that of the first embodiment, illustration is omitted or the same reference numerals are given in the drawings and described.

[0089] FIG. 11(a) is a perspective view showing a feeding roller unit 10 and a weight member 371 according to the fourth embodiment, and FIG. 11(b) is another perspective view showing the feeding roller unit 10. FIG. 11(c) is an exploded perspective view showing the feeding roller unit 10 and the weight member 371.

[0090] As shown in FIGS. 11(a) to 11(c), in the present embodiment, the weight member 371 is detachably supported by the feeding roller unit 10. The roller holder 11 of the feeding roller unit 10 has a top surface 11d and a holding portion 92 provided on the top surface 11d. The holding portion 92 holds the weight member 371 on the same side as the pickup roller 12 with respect to the swing axis 91 of the roller holder 11. More specifically, the holding portion 92 has a pair of snap fits 11f that sandwich the weight member 371 and a pair of ribs 11g. Claw portions are provided at the tips of the ribs 11g, and the claw portions function as a retaining means for the weight member 371. That is, the holding portion 92 as a support portion is in contact with the weight member 371 in a state where the weight member 371 is attached to the feeding roller unit 10. In this way, the holding portion 92 is configured such that the attachment work is not complicated like a spring and the weight member 371 can be easily attached and detached.

[0091] The detachable unit and the weight member 371 as the second biasing member act to increase the feeding pressure of the pickup roller 12 when mounted on the holding portion 92 of the roller holder 11. Also, similar to the first embodiment, the biasing force of the first feeding pressure spring 16 (see Fig. 3(a)) also acts to increase the feeding pressure of the pickup roller 12 via the arm unit 15 and the roller holder 11.

[0092] That is, when the pickup roller 12 feeds the sheet S, the feeding pressure applied to the sheet S is the first feeding pressure N1 by the first feeding pressure spring 16 and the weight member 371 when the weight member 371 is mounted on the feeding roller unit 10. The first feeding pressure N1 is the sum of the biasing force received by the pickup roller 12 from the first feeding pressure spring 16 and the load received by the pickup roller 12 from the weight member 371. Note that the first feeding pressure N1 in the present embodiment does not necessarily have to be set the same as the first feeding pressure N1 in the first and second embodiments.

[0093] As described above, in the present embodiment, by attaching and detaching the weight member 371 to and from the feeding roller unit 10, the same effects as those of the first embodiment can be achieved. Also, the shape, material, size, and weight of the weight member 371 are not limited and may be arbitrarily set.

[0094] <Other Embodiments> Note that in the present embodiment, the cassette 30 is configured to be detachable from the apparatus main body 1A, but it is not limited to this. For example, instead of the cassette 30, a loading portion may be integrally provided on the apparatus main body 1A. And the user may insert and load the sheet S onto the loading portion provided on the apparatus main body 1A. In this case, the swing mechanism 80 becomes unnecessary, and separately, the first feeding pressure spring 16 may be configured to apply a feeding pressure to the pickup roller 12.

[0095] In addition, in this embodiment, the cassette 30 is provided with a liftable intermediate plate 32, but the present invention is not limited to this. For example, the intermediate plate 32 may be omitted, and the pickup roller 12 may be lowered to bring the sheet S into contact with the pickup roller 12, so that the sheet S can be fed.

[0096] In addition, in this embodiment, the roller holder 11 holds the pickup roller 12 and the feed roller 13, but the present invention is not limited to this. For example, the roller holder 11 may hold only the pickup roller 12 so as to be swingable or liftable.

[0097] In addition, the disclosure of this embodiment includes the following configuration examples and method examples. (Configuration 1) A device main body, A loading part supported by the device main body and capable of loading a sheet, A feed roller for feeding the sheet loaded on the loading part, and a holding member for swingably holding the feed roller, a feed roller unit having the same, A first biasing member for biasing the holding member so that the feed roller presses the sheet loaded on the loading part, A detachable unit detachably supported by at least one of the feed roller unit and the device main body, and having a second biasing member for biasing the holding member, When the feed roller feeds the sheet loaded on the loading part, the feed pressure applied to the sheet is a first feed pressure by the first biasing member and the second biasing member when the detachable unit is mounted, and a second feed pressure different from the first feed pressure by the first biasing member when the detachable unit is removed. A sheet feeding device characterized by the above. (Configuration 2) The feed roller unit is detachably supported by the device main body. The sheet feeding device according to Configuration 1, characterized by the above. (Configuration 3) The loading part is detachably supported with respect to the apparatus main body. The apparatus main body has an opening through which the loading part passes when attaching / detaching with respect to the apparatus main body. The attaching / detaching unit is accessible from the opening in a state where the loading part is removed from the apparatus main body. The sheet feeding device according to Configuration 1 or 2, characterized by the above. (Configuration 4) The sheet feeding device further includes a swinging mechanism including the first biasing member, which swings the feeding roller from a first position to a second position below the first position by attaching the loading part to the apparatus main body. The sheet feeding device according to Configuration 3, characterized by the above. (Configuration 5) The swinging mechanism has a contact part that contacts the holding member and a swinging part that swings the feeding roller between the first position and the second position via the holding member. The first biasing member biases the feeding roller toward the second position via the swinging part in a state where the loading part is attached to the apparatus main body. The sheet feeding device according to Configuration 4, characterized by the above. (Configuration 6) The attaching / detaching unit is detachably supported with respect to the feeding roller unit. The sheet feeding device according to any one of Configurations 1 to 5, characterized by the above. (Configuration 7) The attaching / detaching unit has a first contact member that can contact the apparatus main body. The second biasing member is provided between the holding member and the first contact member in a state where the attaching / detaching unit is attached to the feeding roller unit. The sheet feeding device according to Configuration 6, characterized by the above. (Configuration 8) The second biasing member is an elastic member. The sheet feeding device according to Configuration 7, characterized by the above. (Configuration 9) The contact member is rotatably supported within a predetermined range with respect to the holding member so that the second biasing member does not fall off in a state where the detachable unit is attached to the feed roller unit. The sheet feeding device according to Configuration 7 or 8, characterized in that. (Configuration 10) The detachable unit has a weight member that is detachably supported with respect to the feed roller unit. The sheet feeding device according to Configuration 6, characterized in that. (Configuration 11) The holding member has a top surface and a holding portion provided on the top surface for detachably holding the weight member on the same side as the feed roller with respect to the swing axis of the holding member. The sheet feeding device according to Configuration 10, characterized in that. (Configuration 12) The detachable unit is detachably supported with respect to the device body. The sheet feeding device according to any one of Configurations 1 to 5, characterized in that. (Configuration 13) The detachable unit has a second contact member that can contact the holding member. The second biasing member is provided between the device body and the second contact member in a state where the detachable unit is attached to the device body. The sheet feeding device according to Configuration 12, characterized in that. (Configuration 14) The second biasing member is detachably supported on each of the device body and the feed roller unit. The sheet feeding device according to any one of Configurations 1 to 5, characterized in that. (Configuration 15) The second biasing member is an elastic member. The sheet feeding device according to Configuration 13 or 14, characterized in that. (Configuration 16) The loading part includes a loading member on which the sheet is loaded, and an attachment member that is detachably attached to the upper surface of the loading member and supports the sheet so as to be swingable in the sheet width direction orthogonal to the sheet feeding direction. The sheet feeding device according to any one of Configurations 1 to 15, characterized by this. (Configuration 17) The attachment member is arranged so as to overlap with the feeding roller in the sheet width direction. The sheet feeding device according to Configuration 16, characterized by this. (Configuration 18) A device main body, A loading part supported by the device main body and capable of loading a sheet, A feeding roller unit including a feeding roller that feeds the sheet loaded on the loading part, A detachable unit capable of adjusting the feeding pressure applied to the sheet when the feeding roller feeds the sheet loaded on the loading part, The detachable unit is detachably supported by at least one of the feeding roller unit and the device main body, The feeding pressure becomes a first feeding pressure when the detachable unit is attached, and becomes a second feeding pressure different from the first feeding pressure when the detachable unit is removed. The sheet feeding device, characterized by this. (Configuration 19) A device main body, A loading part supported by the device main body and capable of loading a sheet, A feeding roller unit having a feeding roller that feeds the sheet loaded on the loading part and a holding member that holds the feeding roller swingably, A first biasing member that biases the holding member so that the feeding roller presses the sheet loaded on the loading part, At least one of the feeding roller unit and the device main body includes a support part for detachably supporting a detachable unit having a second biasing member that biases the holding member. The support portion abuts against the second biasing member in a state where the detachable unit is attached. When the feeding roller feeds the sheet loaded on the stacking portion, the feeding pressure applied to the sheet is a first feeding pressure by the first biasing member and the second biasing member in a state where the detachable unit is attached, and is a second feeding pressure different from the first feeding pressure by the first biasing member in a state where the detachable unit is removed. A sheet feeding device characterized by the above. (Configuration 20) A sheet feeding device according to any one of Configurations 1 to 19, An image forming unit that forms an image on the sheet fed by the sheet feeding device, An image forming apparatus characterized by the above.

Explanation of Signs

[0098] 1: Image forming apparatus / 1A: Apparatus main body / 10: Feeding roller unit / 11: Holding member (roller holder) / 11c: Support portion (top surface boss) / 11d: Top surface / 11h: Support portion (hook portion) / 12: Feeding roller (pickup roller) / 15: Swing portion (arm unit) / 16: First biasing member (first feeding pressure spring) / 18: Contact portion (cap) / 30: Stacking portion (cassette) / 32: Stacking member (intermediate plate) / 50: Image forming unit / 70, 170: Detachable unit (feeding pressure adjustment mechanism) / 71: Second biasing member, elastic member (second feeding pressure spring) / 72: First contact member, elastic member (spring holder) / 75: Mounting member (envelope placement table) / 80: Swing mechanism / 90: Opening / 91: Swing shaft / 92: Holding portion, support portion / 120a: Support portion (spring engagement portion) / 171: Second biasing member, elastic member (second feeding pressure spring) / 172: Second contact member (contact member) / 220a: Support portion (spring applying portion) / 271: Detachable unit, second biasing member, weight member / FD: Sheet feeding direction / N1: First feeding pressure / N2: Second feeding pressure / W: Sheet width direction

Claims

1. A device main body, a loading part supported by the device main body and capable of loading sheets, a feeding roller for feeding the sheet loaded on the loading part, and a holding member for swingably holding the feeding roller, a feeding roller unit having the same, a first biasing member for biasing the holding member so that the feeding roller presses the sheet loaded on the loading part, a detachable unit detachably supported by at least one of the feeding roller unit and the device main body, the detachable unit having a second biasing member for biasing the holding member, the feeding pressure applied to the sheet when the feeding roller feeds the sheet loaded on the loading part is a first feeding pressure by the first biasing member and the second biasing member when the detachable unit is mounted, and a second feeding pressure different from the first feeding pressure by the first biasing member when the detachable unit is removed, A sheet feeding device characterized by the above.

2. The feeding roller unit is detachably supported with respect to the device main body. The sheet feeding device according to claim 1, characterized by the above.

3. The loading part is detachably supported with respect to the device main body, the device main body has an opening through which the loading part passes when the loading part is attached to and detached from the device main body, the detachable unit is accessible from the opening when the loading part is removed from the device main body, The sheet feeding device according to claim 1, characterized by the above.

4. Further comprising a swing mechanism that includes the first biasing member and swings the feeding roller from a first position to a second position below the first position by attaching the loading part to the device main body. The sheet feeding device according to claim 3, characterized by the above.

5. The swing mechanism has a contact part that contacts the holding member and a swing part that swings the feeding roller between the first position and the second position via the holding member, the first biasing member biases the feeding roller toward the second position via the swing part when the loading part is attached to the device main body, The sheet feeding device according to claim 4, characterized by the above.

6. The detachable unit is detachably supported with respect to the feeding roller unit. The sheet feeding device according to claim 1, characterized by the above.

7. The attachment / detachment unit has a first contact member that can contact the apparatus main body. The second biasing member is provided between the holding member and the first contact member in a state where the attachment / detachment unit is attached to the feeding roller unit. The sheet feeding apparatus according to claim 6, characterized in that.

8. The second biasing member is an elastic member. The sheet feeding apparatus according to claim 7, characterized in that.

9. The contact member is rotatably supported within a predetermined range with respect to the holding member so that the second biasing member does not fall off in a state where the attachment / detachment unit is attached to the feeding roller unit. The sheet feeding apparatus according to claim 7, characterized in that.

10. The attachment / detachment unit has a weight member that is detachably supported with respect to the feeding roller unit. The sheet feeding apparatus according to claim 6, characterized in that.

11. The holding member has a top surface and a holding portion provided on the top surface for detachably holding the weight member on the same side as the feeding roller with respect to the swing axis of the holding member. The sheet feeding apparatus according to claim 10, characterized in that.

12. The attachment / detachment unit is detachably supported with respect to the apparatus main body. The sheet feeding apparatus according to claim 1, characterized in that.

13. The attachment / detachment unit has a second contact member that can contact the holding member. The second biasing member is provided between the apparatus main body and the second contact member in a state where the attachment / detachment unit is attached to the apparatus main body. The sheet feeding apparatus according to claim 12, characterized in that.

14. The second biasing member is detachably supported on each of the apparatus main body and the feeding roller unit. The sheet feeding apparatus according to claim 1, characterized in that.

15. The second biasing member is an elastic member. The sheet feeding apparatus according to claim 13, characterized in that.

16. The stacking unit has a stacking member on which sheets are stacked, and an attachment member that is detachably attached to the upper surface of the stacking member and supports the sheet so as to be swingable in the sheet width direction orthogonal to the sheet feeding direction. The sheet feeding apparatus according to claim 1, characterized in that.

17. The attachment member is arranged so as to overlap the feeding roller in the sheet width direction. The sheet feeding apparatus according to claim 16, characterized in that.

18. Apparatus main body, A loading part supported by the apparatus main body and capable of loading a sheet, A feeding roller unit including a feeding roller for feeding the sheet loaded on the loading part, A detachable unit capable of adjusting a feeding pressure applied to the sheet when the feeding roller feeds the sheet loaded on the loading part, and The detachable unit is detachably supported by at least one of the feeding roller unit and the apparatus main body, The feeding pressure becomes a first feeding pressure when the detachable unit is attached, and becomes a second feeding pressure different from the first feeding pressure when the detachable unit is removed, A sheet feeding apparatus characterized by the above.

19. An apparatus main body, A loading part supported by the apparatus main body and capable of loading a sheet, A feeding roller unit having a feeding roller for feeding the sheet loaded on the loading part and a holding member for swingably holding the feeding roller, A first biasing member for biasing the holding member so that the feeding roller presses the sheet loaded on the loading part, At least one of the feeding roller unit and the apparatus main body includes a support part for detachably supporting a detachable unit having a second biasing member for biasing the holding member, The support part abuts against the second biasing member when the detachable unit is attached, The feeding pressure applied to the sheet when the feeding roller feeds the sheet loaded on the loading part becomes a first feeding pressure by the first biasing member and the second biasing member when the detachable unit is attached, and becomes a second feeding pressure different from the first feeding pressure by the first biasing member when the detachable unit is removed, A sheet feeding apparatus characterized by the above.

20. An image forming apparatus comprising: the sheet feeding apparatus according to any one of Claims 1 to 19; and An image forming part for forming an image on the sheet fed by the sheet feeding apparatus. Characterized by the above.

Images