SHEET FEEDING DEVICE AND IMAGE FORMING APPARATUS INCORPORATING THE SAME

Abstract

A sheet feeding device includes a body, a sheet tray including a contacted portion, a conveyance roller pair, and a contact-separation mechanism. The conveyance roller pair in the body includes one roller and another roller. The contact-separation mechanism includes a spring and a movable part. The movable part pushed by the spring in a first direction has a contact portion and an elongated guide. The contact portion contacts the contacted portion in response to an insertion of the sheet tray into the body to move the movable part in a second direction opposite to the first direction. The elongated guide changes a position of said another roller in a third direction orthogonal to the first and second directions with respect to the one roller according to a movement of the movable part in the first direction and second direction.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119 (a) to Japanese Patent Application No. 2023-034344, filed on Mar. 7, 2023, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND

Technical Field

Embodiments of the present disclosure generally relate to a sheet feeding device to feed a sheet and an image forming apparatus incorporating the feeding device. Such an image forming apparatus is, for example, a copier, a printer, a facsimile machine, or a multifunction peripheral having at least two of copying, printing, scanning, facsimile, and plotter functions.

Related Art

Known image forming apparatuses such as printers include a sheet tray to store sheets. The sheet tray is detachably attached to the body of the image forming apparatus. In other words, the sheet tray is drawable form the body of the image forming apparatus. A conveyance roller pair is located downstream from the sheet tray in a sheet conveyance direction in which the sheet is conveyed. The conveyance roller pair conveys the sheet to a portion downstream from the conveyance roller pair.

SUMMARY

This specification describes an improved sheet feeding device that includes a body, a sheet tray, a conveyance roller pair, and a contact-separation mechanism. The sheet tray is insertable to and removable from the body to store a sheet and includes a contacted portion. The conveyance roller pair is in the body to convey the sheet stored in the sheet tray to a conveyance passage in the body and includes one roller and another roller. The contact-separation mechanism contacts or separates said another roller to and from the one roller. The contact-separation mechanism includes a spring and a movable part pushed in a first direction by the spring. The movable part has a contact portion and an elongated guide. The contact portion is contactable with the contacted portion of the sheet tray in response to an insertion of the sheet tray into the body to move the movable part in a second direction opposite to the first direction against the spring. The elongated guide changes a position of said another roller in a third direction orthogonal to the first direction and the second direction with respect to the one roller according to a movement of the movable part in the first direction or the second direction.

This specification also describes an image forming apparatus including the sheet feeding device.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein:

FIG. 1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present disclosure;

FIG. 2 is a diagram illustrating a configuration of a part of a sheet feeding device according to an embodiment of the present disclosure;

FIGS. 3A to 3C are diagrams illustrating a procedure in which a first tray is pulled out from a body of a sheet feeding device to remove a jammed sheet, according to an embodiment of the present disclosure;

FIGS. 4A and 4B are diagrams illustrating a contact-separation mechanism and a sheet tray;

FIG. 5 is an enlarged view of openings in an elongated guide;

FIG. 6 is a diagram illustrating parts of a conveyance roller pair, a driver, and a contact-separation mechanism viewed in a direction orthogonal to an axial direction;

FIG. 7 is a top view of a sheet tray;

FIG. 8 is a diagram illustrating a contact-separation mechanism and a sheet tray according to a first modification; and

FIG. 9 is a diagram illustrating a contact-separation mechanism and a sheet tray according to a second modification.

The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.

DETAILED DESCRIPTION

In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.

Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

With reference to drawings, descriptions are given below of embodiments of the present disclosure. In the drawings illustrating embodiments of the present disclosure, elements or components having identical or similar functions or shapes are given similar reference numerals as far as distinguishable, and redundant descriptions are omitted.

Initially, with reference to FIG. 1, a configuration and operation of an image forming apparatus 1 according to an embodiment of the present disclosure is described below.

In FIG. 1, the image forming apparatus 1 that is a printer includes a photoconductor drum 2, a charger 3, an exposure device 6, a developing device 4, a transfer device 7, and a cleaner 5. The charger 3 charges the surface of the photoconductor drum 2. The exposure device 6 irradiates the charged surface of the photoconductor drum 2 with laser light L to form an electrostatic latent image on the surface of the photoconductor drum 2. The developing device 4 develops the electrostatic latent image formed on the surface of the photoconductor drum 2 to form a toner image. The transfer device 7 transfers the toner image formed on the surface of the photoconductor drum 2 to a sheet P. The cleaner 5 cleans untransferred toner that is not transferred to the sheet and remains on the surface of the photoconductor drum 2.

The image forming apparatus 1 further includes a sheet feeding device 11, sheet feeding mechanisms 51, a first conveyance roller pair 61, a second conveyance roller pair 62, a third conveyance roller pair 63, a registration roller pair 17 that is a timing roller pair, a fixing device 20, and a stack tray 31. The sheet feeding device 11 includes a first sheet tray 12, a second sheet tray 13, and a third sheet tray 14. The sheet feeding mechanisms 51 feed sheets stored in the first to third sheet trays 12 to 14. The first to third conveyance roller pairs 61 to 63 are disposed in a first to third conveyance passages K1 to K3. The registration roller pair 17 conveys the sheet P to the position of the transfer device 7. The fixing device 20 fixes the toner image (that is an unfixed image) borne on the sheet P onto the sheet P. The sheet P is ejected from the body of the image forming apparatus 1 to the stack tray 31 and stacked on the stack tray 31.

The front side of the image forming apparatus 1 described above is the left side of the image forming apparatus 1 in FIG. 1 and FIGS. 3A to 3C. An operator is in front of the front side to operate the image forming apparatus 1. The first to third sheet trays 12 to 14 are pulled out from the front side. In contrast, the back side of the image forming apparatus 1 is the right side of the image forming apparatus 1 in FIG. 1 and FIGS. 3A to 3C. The back side is highly likely to face the wall of the office room. The first to third conveyance passages K1 to K3 and the first to third conveyance roller pairs 61 to 63 are closer to the back side than the front side.

With reference to FIG. 1, typical image forming processes of the image forming apparatus 1 are described below.

An input device such as a personal computer is coupled to the image forming apparatus 1 to send image data to the image forming apparatus 1. The image data is input to the exposure device 6, and the exposure device 6 emits the laser light L based on the image data toward the photoconductor drum 2.

The photoconductor drum 2 rotates counterclockwise in FIG. 1, and a charging process, an exposure process, and a developing process that are the typical image forming processes form an image (that is a toner image) corresponding to the image data on the photoconductor drum 2.

The image formed on the photoconductor drum 2 is transferred onto the sheet P conveyed by the registration roller pair 17 at the position of the transfer device 7.

The sheet P is conveyed to the position of the transfer device 7 as follows.

First, one of the first to third sheet trays 12 to 14 arranged vertically in a lower portion of the image forming apparatus 1 is automatically or manually selected. For example, it is assumed that the third sheet tray 14 at the lowermost stage is selected. The sheet feeding mechanism 51 feeds the uppermost one of the sheets P stored in the third sheet tray 14 toward the third conveyance roller pair 63. The sheet is conveyed along the third conveyance passage K3 in which the third conveyance roller pair 63 is disposed, the second conveyance passage K2 in which the second conveyance roller pair 62 is disposed, and the first conveyance passage K1 in which the first conveyance roller pair 61 is disposed in this order.

Subsequently the sheet P reaches the position of the registration roller pair 17. When the sheet P reaches the registration roller pair 17, the registration roller pair 17 does not rotate. The leading edge of the sheet P strikes a nip formed by the rollers of the registration roller pair 17, which corrects the skew of the sheet P.

Then, the registration roller pair 17 starts rotating again, and the sheet P is then conveyed toward the transfer device 7 in synchrony with movement of the toner image formed on the surface of the photoconductor drum 2 for forming the toner image on the sheet P at the correct position. The image formed on the surface of the photoconductor drum 2 is transferred onto the sheet P by the transfer device 7. This process is referred to as a transfer process.

After passing through the position of the transfer device 7, the sheet P having been subjected to the transfer process passes through the conveyance path and reaches the fixing device 20. In the fixing device 20, the sheet P is conveyed between a fixing roller and a pressure roller, so that the toner image is fixed to the sheet P by application of heat applied by the fixing roller and pressure applied at a fixing nip by the fixing roller and the pressure roller, which is referred to as a fixing process. After the toner image is fixed onto the sheet P in the fixing process, the sheet P is sent out from the fixing device 20, ejected from the image forming apparatus 1, and is placed on the stack tray 31 as an output image.

Thus, a series of the image forming processes (print job) is completed.

The following describes the sheet feeding mechanism 51 in the sheet feeding device according to the present embodiment in detail with reference to FIG. 2.

The following describes the sheet feeding mechanism 51 that feeds the sheet P stored in the second sheet tray 13 in the middle stage among the first to third sheet trays 12 to 14. The sheet feeding mechanism to feed the sheet stored in the first sheet tray 12 or the third sheet tray 14 has the substantially same structure as the sheet feeding mechanism 51 to feed the sheet P stored in the second sheet tray 13. For this reason, the description of the sheet feeding mechanism to feed the sheet stored in the first sheet tray 12 or the third sheet tray 14 is omitted.

With reference to FIG. 2, the sheet tray 13 includes a sheet stacker 43 and the sheet feeding mechanism 51. The multiple sheets P that is a sheet bundle Pt are stacked on the sheet stacker 43. The sheet feeding mechanism 51 feeds the sheet of the sheets P stacked on the sheet stacker 43.

The sheet stacker 43 is partly movable vertically (i.e., in the vertical direction) such that a downstream side (i.e., the right side in FIG. 2) in the sheet conveyance direction of the uppermost sheet P of the sheet bundle PT placed on the sheet stacker 43 reaches a given height position, which is a position where the uppermost sheet P contacts a pickup roller 52. Specifically, the sheet stacker 43 includes an elevation plate and a fixed plate. The elevation plate is rotatable around a rotary center shaft 43a. The fixed plate is a plate that does not move vertically. The elevation plate is disposed downstream from the fixed plate in the sheet conveyance direction and rotates around the rotary center shaft 43a in the forward and reverse directions. By so doing, the elevation plate moves in the vertical direction.

Referring to FIG. 2, the sheet feeding mechanism 51 includes a feed roller 53, the pickup roller 52, and a separation roller 54.

The feed roller 53 is disposed on the leading end (i.e., downstream end) of the sheets P stacked on the sheet stacker 43 in the sheet conveyance direction that is the direction indicated by white arrow in FIG. 2. The feed roller 53 rotates counterclockwise in FIG. 2 along the sheet conveyance direction while contacting the upper face of the uppermost sheet P of the sheets P on a sheet stacker 42, so that the sheet P is conveyed in the sheet conveyance direction indicated by the arrow drawn by an alternate long and short dash line in FIG. 2. The pickup roller 52 rotates counterclockwise in FIG. 2 along the sheet conveyance direction while contacting the upper face of the uppermost sheet P stacked on the sheet stacker 43, so that the uppermost sheet P is conveyed toward the feed roller 53. The pickup roller 52 can contact and separate from the sheet P (i.e., the uppermost sheet P) stacked on the sheet stacker 43 (i.e., the elevation plate). In other words, the pickup roller 52 is movable between a retracted position at which the pickup roller 52 does not contact the sheet P stacked on the sheet stacker 43 and a contact position at which the pickup roller 52 contacts the sheet P as illustrated in FIG. 2.

The separation roller 54 is disposed to form a nip region with the feed roller 53.

The separation roller 54 rotates in the forward direction, which is the clockwise direction indicated by broken arrow in FIG. 2, along the sheet conveyance direction when a single sheet P is sandwiched in the nip region or when no sheet P is sandwiched in the nip region. By contrast, when multiple sheets P are sandwiched in the nip region, the separation roller 54 rotates in a reverse direction opposite to the above-described forward direction. In other words, the separation roller 54 rotates counterclockwise as indicated by solid arrow in FIG. 2. As a result, the uppermost sheet P of the multiple sheets P sandwiched in the nip region is fed in the sheet conveyance direction along the rotation of the feed roller 53 while the subsequent sheet or sheets P of the multiple sheets P are conveyed in the direction opposite to the sheet conveyance direction (i.e., the forward direction). Thus, the multiple feeding of the sheets P or continuous feeding is reduced or prevented.

In the present embodiment, a plate-shaped separation pad may be used instead of the separation roller 54.

In the sheet tray 13, the sheet stacker 43 (i.e., the elevation plate) moves in the vertical direction depending on the number of sheets P stacked on the sheet stacker 43 so that the pickup roller 52 can contact the uppermost sheet P placed on the top of the sheet bundle PT stacked on the sheet stacker 43. Then, the sheet feeding operation of the sheets P starts after the pickup roller 52 is lowered to a position where the pickup roller 52 contacts the upper face of the uppermost sheet P on the sheets P stacked on the sheet stacker 43 (i.e., the elevation plate) whose position in the vertical direction has been adjusted.

The sheet tray 13 according to the present embodiment includes a pair of side fences that restricts the position in the width direction of the sheet P stacked on the sheet stacker 43. The width direction is a direction orthogonal to the face of the paper on which FIG. 2 is drawn. The side fences are disposed at both lateral ends of the sheet P. In other words, at both ends in the width direction of the sheet P, the side fences sandwich the sheet P. A manual movement assembly can move side fences simultaneously with each other in the width direction (in other words, the space between the side fences in the width direction can be increased and decreased) in accordance with the size of the sheet P in the width direction.

The sheet tray 13 according to the present embodiment further includes a reference fence 107 and an end fence 103 each regulating the position of the sheet P on the sheet stacker 43 in the sheet conveyance direction. The sheet conveyance direction is the horizontal direction, or the lateral direction, in FIG. 2. The reference fence 107 is disposed such that a downstream side face of the sheet P in the sheet conveyance direction (i.e., the leading end of the sheet P in the sheet conveyance direction) contacts the reference fence 107. The end fence 103 is disposed to contact an upstream side face of the sheet P in the sheet conveyance direction (i.e., the trailing end of the sheet P in the sheet conveyance direction). The end fence 103 can be moved by the manual moving assembly in the sheet conveyance direction so as to conform to the size of the sheet P in the sheet conveyance direction.

Referring now to FIGS. 3 to 7, a detailed description is given of a configuration and operation of the sheet feeding device 11 of the image forming apparatus 1 according to the present embodiment.

Referring to FIGS. 1 and 3, the sheet feeding device 11 according to the present embodiment includes three sheet trays 12 to 14 to store sheets P. The sheet trays 12 to 14 are arranged in the vertical direction to overlap each other, forming three stages. The sheet trays 12 to 14 are insertable to and removable from a body of the sheet feeding device 11. In other words, the sheet trays 12 to 14 can be pulled out from the body of the sheet feeding device 11. For example, a guide rail including one side plate fixed to the body of the sheet feeding device 11, the other side plate fixed to the sheet tray, and a slide assist member such as ball bearings between the one side plate and the other side plate enables the sheet tray to be insertable to and removable from the body of the sheet feeding device 11.

The sheet feeding mechanism 51 is disposed downstream from each of the sheet trays 12 to 14 in the sheet conveyance direction, and each of conveyance roller pairs 61 to 63 and conveyance passages K1 to K3 are disposed downstream from the sheet feeding mechanism 51 in the sheet conveyance direction as illustrated in FIG. 1.

In the specification of the present application, the definition of “each of the sheet trays 12 to 14 insertable to and removable from the body of the sheet feeding device 11 is removed from the body of the sheet feeding device 11” includes not only a state in which each of the sheet trays 12 to 14 is completely removed from the body of the sheet feeding device 11 as illustrated in FIG. 3C in which the sheet tray 12 is completely removed from the body of the sheet feeding device 11 but also a state in which a part of the sheet trays 12 to 14 is pulled out from the body of the sheet feeding device 11 and held by the body of the sheet feeding device 11 as illustrated in FIG. 3B.

Specifically, referring to FIG. 3A, the first conveyance roller pair 61 is disposed in a conveyance path through which the sheet P fed from the first sheet tray 12 passes. In detail, the sheet P fed from the first sheet tray 12 passes through the first conveyance roller pair 61 and the first conveyance passage K1.

The sheet P fed from the second sheet tray 13 passes through the second conveyance roller pair 62, the second conveyance passage K2, the first conveyance roller pair 61, and the first conveyance passage K1.

The sheet P fed from the third sheet tray 14 passes through the third conveyance roller pair 63, the third conveyance passage K3, the second conveyance roller pair 62, the second conveyance passage K2, the first conveyance roller pair 61, and the first conveyance passage K1.

The following describes the first sheet tray 12 that is an upper stage, the first conveyance roller pair 61, and the first conveyance passage K1 among the three sheet trays 12 to 14 and the three conveyance roller pairs 61 to 63. The other sheet trays 13 and 14 and the conveyance roller pairs 62 and 63 have substantially the same configurations, and thus the description thereof will be omitted.

Referring to FIGS. 3A to 7, the sheet feeding device 11 according to the present embodiment includes the first sheet tray 12 as the sheet tray and the first conveyance roller pair 61 as the conveyance roller pair.

The first sheet tray 12 is insertable to and removable from the body of the sheet feeding device 11 and functions as the sheet tray to store the sheet P (or multiple sheets P).

The first conveyance roller pair 61 is disposed in the body of the sheet feeding device 11 so as not to be attached to and detached from the body of the sheet feeding device 11 in conjunction with the attachment and detachment operation of the first sheet tray 12 as the sheet tray. The first conveyance roller pair 61 functions as the conveyance roller pair that conveys the sheet P fed from the first sheet tray 12 as the sheet tray installed to the body of the sheet feeding device 11 to the conveyance passage K1. The first conveyance roller pair 61 as the conveyance roller pair includes a driving roller 61a as one roller and a driven roller 61b as another roller. A nip is formed between the two rollers that are the driving roller 61a and the driven roller 61b, and the two rollers rotate along the sheet conveyance direction to nip and convey the sheet P. A driver 90 (see FIGS. 4A, 4B, and 6) drives and rotates the driving roller 61a as the one roller. The driven roller 61b as said another roller is in contact with the driving roller 61a and is rotated in conjunction with the rotation of the driving roller 61a.

The first conveyance roller pair 61, the second conveyance roller pair 62, and the third conveyance roller pair 63 as the conveyance roller pairs are downstream (the right side in FIGS. 1, 3, and 5) from the first sheet tray 12, the second sheet tray 13, and the third sheet tray 14 as sheet trays in the attachment direction in which the first sheet tray 12, the second sheet tray 13, and the third sheet tray 14 are attached, respectively.

The body of the image forming apparatus 1 is placed such that the front side of the image forming apparatus 1 is the upstream side in the attachment direction (the left side in FIGS. 1, 3, and 5), and the back side of the image forming apparatus 1 is the downstream side in the attachment direction (the right side in FIGS. 1, 3, and 5). For this reason, it is assumed that the image forming apparatus 1 is placed such that the back side of the image forming apparatus 1 faces the wall of a room. It is preferable that the sheet P jammed at each of the positions of the first to third conveyance roller pairs 61 to 63 is not removed by opening the exterior cover on the back side, but can be removed from the other side (particularly, the front side in which the operator operates the image forming apparatus 1). In other words, an insertion and removement direction of the sheet tray is preferably in the conveyance direction, and the conveyance roller pair is downstream from the sheet tray in the conveyance direction.

Referring to FIG. 4 (and FIG. 3), the sheet feeding device 11 according to the present embodiment includes a contact-separation mechanism 79 that brings the driving roller 61a as the one roller and the driven roller 61b as said another roller of the first conveyance roller pair 61 as the conveyance roller pair into contact with each other and separates the driving roller 61a and the driven roller 61b from each other.

The contact-separation mechanism 79 is configured to separate the driven roller 61b from the driving roller 61a in conjunction with an operation of separating (drawing) the first sheet tray 12 as the sheet tray from the body of the sheet feeding device 11.

As illustrated in FIGS. 3A and 4A, when the first sheet tray 12 is installed to the body of the sheet feeding device 11 to perform printing, the driving roller 61a and the driven roller 61b are in contact with each other such that the first conveyance roller pair 61 can convey the sheet P.

As illustrated in FIGS. 3B and 4B, pulling out the first sheet tray 12 from the body of the sheet feeding device 11 causes the contact-separation mechanism 79 to separate the driven roller 61a from the driving roller 61b after the image forming apparatus 1 including the driving roller 61a stops driving to stop printing. When the sheet P is jammed at the position of the first conveyance roller pair 61 as illustrated in FIG. 3B, separating the driving roller 61a and the driven roller 61b from each other in this way enables inserting a hand into a space formed by pulling out the first sheet tray 12 and easily taking out (in other words, removing) the jammed sheet P in the direction of the black arrow in FIG. 3C.

As illustrated in FIG. 3C, when the operator pulls the sheet P in the direction of the black arrow to remove the jammed sheet, the driven roller 61b of the first conveyance roller pair 61 is separated from the driving roller 61a, but the feed roller 53 of the sheet feeding mechanism 51 (see FIGS. 1 and 2) contacts the separation roller 54 of the sheet feeding mechanism 51. However, since the separation roller 54 is configured to be rotatable in the reverse direction to convey the sheet in a direction opposite to the sheet conveyance direction as described above, the separation roller 54 does not generate a large load that prevents the sheet P from being pulled out in the direction of the black arrow to remove the jammed sheet by the operator.

As described above, pulling out the first sheet tray 12 in the sheet feeding device 11 according to the present embodiment switches the first conveyance roller pair 61 from a contact state to a separation state, which enables pulling out the first sheet tray 12 from the body of the sheet feeding device 11 and easily removing the sheet jammed at the nip of the first conveyance roller pair 61. In other words, the above-described structure enables an easy jam process.

After the first sheet tray 12 is removed from the body of the sheet feeding device 11, the first sheet tray 12 is installed into the body of the sheet feeding device 11. In conjunction with the movement to push the first sheet tray 12 into the body of the sheet feeding device 11, the contact-separation mechanism 79 moves the driven roller 61b to be in contact with the driving roller 61a.

As illustrated in FIG. 6, a driving gear 61x is disposed at one end of the rotation shaft of the driving roller 61a. The driving gear 61x is engaged with a motor gear 92 disposed on a motor shaft of a driving motor 91, and the driving force of the driving motor 91 is transmitted to the driving gear 61x. A controller controls the driving motor 91 to drive and rotate the driving roller 61a in a predetermined direction (that is, counterclockwise in FIG. 4). As described above, the above-described parts such as the driving motor 91 and the motor gear 92 functions as the driver 90 to drive and rotate the driving roller 61a.

Referring to FIGS. 4A to 7, the following describes a configuration and operation of the contact-separation mechanism 79 in detail.

As described above with reference to FIGS. 3A to 4B, the contact-separation mechanism 79 separates the driven roller 61b as said another roller from the driving roller 61a as the one roller in the first conveyance roller pair 61 as the conveyance roller pair in conjunction with the operation to separate the first sheet tray 12 as the sheet tray from the body of the sheet feeding device 11. Specifically, the contact-separation mechanism 79 moves the driven roller 61b of the first conveyance roller pair 61 to contact and separate the driving roller 61a in conjunction with the attachment and detachment operation of the first sheet tray 12.

As illustrated in FIGS. 4A, 4B, and 6, the contact-separation mechanism 79 in the present embodiment includes movable parts 80 and compression springs 84 as biasing members.

As illustrated in FIG. 6, the contact-separation mechanism includes the movable parts 80 disposed at both end portions of the sheet feeding device 11 in the axial direction of the rotation shaft of the driven roller 61b that is the width direction. In other words, the sheet feeding device 11 includes one contact-separation mechanism including the movable part 80 in one end portion of the sheet feeding device 11 in the axial direction and another contact-separation mechanism including the movable part 80 in another end portion in the axial direction. The movable part 80 has an elongated guide 81. A housing of the sheet feeding device 11 holds the movable parts 80 so as to be movable in the vertical direction. In other words, the movable part 80 can move downward as a first direction and upward as a second direction.

On the other hand, a holder 70 rotatably holds both ends of the rotation shaft of the driven roller 61b. The holder 70 includes fitting portions 70a projecting from both sides in the axial direction toward the outside of the holder 70 in the axial direction. The movable parts 80 hold the holder 70 (and the driven roller 61b) so as to be movable in a horizontal direction as a third direction in the sheet feeding device 11.

The elongated guide 81 of the movable part 80 has an opening as illustrated in FIG. 5 in the movable part 80 and moves in a predetermined direction that is a moving direction of the movable part 80, a downward direction as the first direction, and the direction indicated by an arrow in FIG. 4B in conjunction with the operation to separate (pull out) the first sheet tray 12 as the sheet tray from the body of the sheet feeding device 11 to move the driven roller 61b in a separating direction indicated by a black thick arrow in FIG. 4B and a rightward direction in FIG. 4B as the third direction.

Specifically, the elongated guide 81 has a first opening 81a, a second opening 81b, and a third opening 81c as illustrated in FIG. 5.

The first opening 81a is a most downstream (lowermost) opening in the predetermined direction as the first direction and has a rectangular shape extending in the predetermined direction that is the vertical direction in FIG. 5.

The second opening 81b is a most upstream opening above the first opening 81a in the predetermined direction and has a rectangular shape extending in the predetermined direction as the first direction that is the vertical direction. The second opening 81b is at a position farther from the driving roller 61a as the one roller than the first opening 81a. In other words, the second opening 81b is shifted from the first opening 81a in the third direction farther from the driving roller 61a as the one roller than the first opening 81a.

The third opening 81c connects the first opening 81a and the second opening 81b. The third opening 81c extends obliquely upward from below and has a constant width that is the length of the fitting portion 70a in the longitudinal direction +α.

The fitting portion 70a of the holder 70 rotatably holding the driven roller 61b is fitted to the opening of the elongated guide 81.

In the above-described structure, falling the movable parts 80 from the position of FIG. 4A to the position of FIG. 4B moves the fitting portion 70a rightward along the shape of the opening of the elongated guide 81, and the driven roller 61b also moves rightward as the third direction. As a result, the driven roller 61a separates from the driving roller 61b.

In contrast, moving the movable parts 80 upward as the second direction from the position of FIG. 4B to the position of FIG. 4A moves the fitting portion 70a leftward along the shape of the opening of the elongated guide 81, and the driven roller 61b also moves leftward as the third direction. As a result, the driven roller 61a abuts against the driving roller 61b.

As illustrated in FIGS. 4A and 4B, the compression spring 84 as the biasing member of the contact-separation mechanism 79 pushes the movable part 80 so that the elongated guide 81 moves in the predetermined direction (downward in FIG. 4) as the first direction.

Specifically, the compression spring 84 has one end that is an upper end connected to a housing 11x of the sheet feeding device 11 and the other end that is a lower end connected to a lower side of the opening of the movable part 80.

When only the weight of the movable part 80 does not smoothly fall the movable part 80 due to the sliding friction between the elongated guide 81 and the fitting portion 70a, the biasing force of the compression spring 84 is useful to fall the movable part 80 and separate the driven roller 61b from the driving roller 61a.

As illustrated in FIG. 4A, the movable part 80 has a contact portion 83 contactable with a contacted portion 12a of the first sheet tray 12 as the sheet tray.

The contacted portion 12a of the first sheet tray 12 as the sheet tray installed in the body of the sheet feeding device 11 contacts the contact portion 83 of the movable part 80 and restricts the movement of the movable part 80 against the biasing force of the compression spring 84 as the biasing member so that the elongated guide 81 does not move in the predetermined direction (downward).

In other words, the contacted portion 12a of the first sheet tray 12 contacts the contact portion 83 of the movable part 80 and pushes the movable part 80 upward against a spring force of the compression spring 84. In response to an insertion of the first sheet tray into the body of the sheet feeding device 11, the contact portion 83 contacts the contacted portion 12a of the first sheet tray 12 to move the movable part 80 in an upward direction as the second direction against the spring. As illustrated in FIG. 4B, pulling out the first sheet tray 12 releases the contact between the contacted portion 12a and the contact portion 83, and the spring forces of the compression springs 84 and the weight of the movable part 80 move the movable part 80 downward. As a result, the driven roller 61b separates from the driving roller 61a. As illustrated in FIG. 4A, pushing the first sheet tray 12 pulled out as illustrated in FIG. 4B into the body of the sheet feeding device 11 causes the contacted portion 12a to contact and push the contact portion 83 upward and push the movable part 80 upward against the spring forces of the compression springs 84. In other words, the elongated guide 81 changes a movement of the movable part 80 in the moving direction caused by separating the contact portion 83 from the contacted portion 12a due to an operation to pull out the first sheet tray 12 from the body of the sheet feeding device 11, into a movement to separate the driven roller 61b from the driving roller 61a.

The contact portion 83 and the contacted portion 12a have inclined faces as a first inclined face and a second inclined face that face each other. The inclined face inclines with respect to an insertion and removement direction of the sheet tray in order to smoothly perform contact and contact release.

Specifically, the contacted portion 12a is disposed at an end on the downstream side of the first sheet tray 12 in the insertion and removement direction (the right side of the first sheet tray 12 in FIGS. 4A, 4B, and 7) and has the inclined face as the second inclined face projecting from an upper part to a lower part toward the movable part 80. The lower part of the inclined face of the contacted portion 12a is closer to the movable part 80 than the upper part of the inclined face of the contacted portion 12a.

The contact portion 83 is disposed on a lower portion of the movable part 80 and on a side facing the first sheet tray 12 (that is the left side of the movable part 80 in FIG. 4) and has the inclined face as the first inclined face projecting from a lower part to an upper part toward the first sheet tray 12. The upper part of the inclined face of the contact portion 83 is closer to the first sheet tray 12 than the lower part of the inclined face of the contact portion 83.

The lowered position of the movable part 80 after the movable part 80 falls as illustrated in FIG. 4B can be determined by a position of an upper side of the second opening 81b in the elongated guide 81 or by a stopper disposed on the housing of the sheet feeding device 11. The lowered position is determined such that the inclined face as the second inclined face of the contacted portion 12a contacts the inclined face as the first inclined face of the contact portion 83 in conjunction with the operation to move the first sheet tray 12 in the horizontal direction to install the first sheet tray 12 into the body of the sheet feeding device 11.

As described above with reference to FIG. 6, the contact-separation mechanisms 79 are disposed at both end portions of the sheet feeding device 11 in the axial direction. For this reason, the contact portions 83 are disposed at both end portions of the sheet feeding device 11 in the axial direction. In accordance with this, the contacted portions 12a are also disposed at both end portions of the first sheet tray 12 as the sheet tray in the axial direction as illustrated in FIG. 7.

Placing the contact portions 83 of the contact-separation mechanisms 79 and the contacted portions 12a of the first sheet tray 12 at both end portions in the axial direction as described above enables a smooth contact-separation operation of the first conveyance roller pair 61 in a well-balanced manner.

The following describes a first modification of the present embodiment.

As illustrated in FIG. 8, the elongated guide 81 of the movable part 80 in the contact-separation mechanism 79 according to the first modification includes stoppers 81x that restrict the movement of the fitting portion 70a of the holder 70 holding the driven roller 61b in the first opening 81a (see FIG. 5) in the predetermined direction that is the downward direction and the moving direction of the movable part 80 as the first direction.

Bringing the contacted portion 12a of the first sheet tray 12 into contact with the contact portion 83 of the movable part 80 pushes the movable part 80 upward to a contact position at which the driven roller 61b contacts the driving roller 61a. If the movable part 80 is further pushed upward from the contact position, the stoppers 81x contact the fitting portions 70a and prevent the fitting portions 70a from moving upward from the contact position.

The above-described structure prevents a disadvantage that the driven roller 61a does not contact the driving roller 61b, and the first conveyance roller pair 61 does not function.

The following describes a second modification of the present embodiment.

As illustrated in FIG. 9, the first sheet tray 12 as the sheet tray in the second modification includes rollers 12a1 rotatably supported on the contacted portion 12a, and the rollers 12a1 contact the contact portions 83 of the movable parts 80.

The rollers 12a1 can reduce the sliding friction generated by bringing the contacted portion 12a into contact with the contact portion 83 and separating the contacted portion 12a from the contact portion 83. The above-described structure enables a smooth attachment and detachment operation of the first sheet tray 12 and a smooth contact-separation operation in the contact-separation mechanism 79 in conjunction with the attachment and detachment operation.

In addition, the elongated guide 81 of the movable part 80 in the second modification has a fourth opening 81m downstream from the first opening 81a (see FIG. 5) in the predetermined direction (below the first opening 81a). The fourth opening 81m has a rectangular shape extending in the predetermined direction that is the vertical direction in FIG. 9 and arranged at a position closer to the driving roller 61a as the one roller than the first opening 81a. In addition, the elongated guide 81 has a fifth opening connecting the first opening 81a to the fourth opening 81m. The fifth opening extends obliquely upward from below and has the constant width that is the length of the fitting portion 70a in the longitudinal direction +α.

The fourth opening 81m is used when the surface layer of the driving roller 61a and the surface layer of the driven roller 61b (that are made of rubber or resin) are worn over time and the nip cannot be formed (when a clearance is formed between the rollers). Specifically, at an initial stage, the fitting portion 70a is fitted in the first opening 81a to bring the driven roller 61b of the first conveyance roller pair 61 into contact with the driving roller 61a of the first conveyance roller pair 61 and fitted in the second opening 81b to separate the driven roller 61b from the driving roller 61a. After the rollers are worn over time and deteriorate, the fitting portion 70a is fitted in the fourth opening 81m to bring the driven roller 61b of the first conveyance roller pair 61 into contact with the driving roller 61a of the first conveyance roller pair 61 and fitted in the first opening 81a to separate the driven roller 61b from the driving roller 61a.

To change the sheet feeding device as described above after the rollers are worn over time and deteriorate, the position of the contact portion 83 of the movable part 80 pushed up by the contacted portion 12a of the first sheet tray 12 is changed to be higher than that at the initial stage. To change the position higher, the roller 12a1′ having a larger outer diameter than the roller 12a1 is attached as illustrated in FIG. 9, or a plate having an appropriate thickness is attached to the inclined face of the contact portion 83 after the rollers are worn over time and deteriorate.

As described above, the sheet feeding device 11 according to the present embodiment includes the first sheet tray 12 as the sheet tray that is detachably attached to the body of the sheet feeding device 11 and can store the sheet P. In addition, the first conveyance roller pair 61 as the conveyance roller pair is disposed on the body of the sheet feeding device 11 to convey the sheet P fed from the first sheet tray 12 installed in the body of the sheet feeding device 11. The sheet feeding device 11 according to the present embodiment further includes the contact-separation mechanism 79 to separate the driven roller 61b as said another roller in the first conveyance roller pair 61 from the driving roller 61b as the one roller in the first conveyance roller pair 61 in conjunction with the operation to pull out the first sheet tray 12 from the body of the sheet feeding device 11. The contact-separation mechanism 79 includes the movable part 80 and the compression spring 84. The movable part 80 includes the elongated guide 81 and the contact portion 83. Moving the elongated guide 81 in the predetermined direction in conjunction with the operation to pull out the first sheet tray 12 moves the driven roller 61b in the separating direction. The contact portion 83 contacts the contacted portion 12a of the first sheet tray 12. The compression spring 84 as the biasing member pushes the movable part 80 to move the movable part 80 in the predetermined direction. The contacted portion 12a of the first sheet tray 12 installed in the body of the sheet feeding device 11 contacts the contact portion 83 of the movable part 80 to restrict the movement of the elongated guide 81 of the movable part 80 in the predetermined direction against the force of the compression spring 84.

The above-described structure enables pulling out the first sheet tray 12 from the body of the sheet feeding device 11 and easily removing the sheet P jammed at the position of the first conveyance roller pair 61 as the conveyance roller pair disposed downstream from the first sheet tray 12 as the sheet tray.

The above-described embodiments and modifications of the present disclosure are applied to the sheet feeding device 11 provided for the image forming apparatus 1 that is a monochrome image forming apparatus. However, the present disclosure is not limited to the above-described sheet feeding device (that is, the sheet feeding device 11). For example, the present disclosure is also applicable to a sheet feeding device provided for a color image forming apparatus.

Further, the above-described embodiments and modifications of the present disclosure are applied to the sheet feeding device 11 provided for the image forming apparatus 1 that employs electrophotography. However, the present disclosure is not limited to the above-described sheet feeding device (that is, the sheet feeding device 11). For example, the present disclosure is also applicable to a sheet feeding device provided for an image forming apparatus that employs an inkjet method or a stencil printing machine.

In the present embodiments and modifications, the sheet feeding device 11 includes the first to third sheet trays 12 to 14 forming three stages, but the number of sheet trays in the sheet feeding device according to the present disclosure may be one, two, or four or more. The sheet feeding device according to the present disclosure may include a manual sheet tray exposed to the outside of the sheet feeding device. As described in the embodiments and modifications, the present disclosure may be applied to a single sheet tray or multiple sheet trays.

In the present embodiments and modifications, the present disclosure is applied to the sheet feeding device 11 including the sheet feeding mechanism 51 that includes the pickup roller 52, the feed roller 53, and the separation roller 54, but the present disclosure is not limited to this. The present disclosure may be applied to the sheet feeding device including other types of feeding mechanisms. In addition, the elongated guide 81 may be formed as a link.

Any of the cases described above exhibits substantially the same advantages as the advantages of the present embodiments and modifications.

The above-described embodiments and modifications are illustrative and do not limit this disclosure. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements at least one of features of different illustrative and exemplary embodiments herein may be combined with each other at least one of substituted for each other within the scope of this disclosure and appended claims. Further, features of components of the embodiments, such as the number, the position, and the shape are not limited to the embodiments and thus may be preferably set to be applied to the present disclosure.

In the present description, the term “sheet” is defined as any sheet-like recording medium, such as general paper, coated paper, label paper, overhead projector (OHP) transparency, or a film sheet.

The present disclosure may be applicable to, for example, a combination of the following First Aspect to Tenth Aspect.

First Aspect

In a first aspect, a sheet feeding device includes a body, a sheet tray, a conveyance roller pair, and a contact-separation mechanism. The sheet tray is insertable to and removable from the body to store a sheet and includes a contacted portion. The conveyance roller pair is in the body to convey the sheet stored in the sheet tray to a conveyance passage in the body and includes one roller and another roller. The contact-separation mechanism contacts or separates said another roller to and from the one roller. The contact-separation mechanism includes a spring and a movable part pushed in a first direction by the spring. The movable part has a contact portion and an elongated guide. The contact portion is contactable with the contacted portion of the sheet tray in response to an insertion of the sheet tray into the body to move the movable part in a second direction opposite to the first direction against the spring. The elongated guide changes a position of said another roller in a third direction orthogonal to the first direction and the second direction with respect to the one roller according to a movement of the movable part in the first direction or the second direction.

Second Aspect

In a second aspect, the sheet feeding device according to the first aspect further includes a holder to hold said another roller. The holder includes a fitting portion fitting to the elongated guide. The elongated guide includes a first opening, a second opening, and a third opening. The first opening has a rectangular shape extending in the first direction. The second opening is shifted from the first opening in the third direction farther from the one roller than the first opening and has a rectangular shape extending in the first direction. The third opening connects the first opening and the second opening and is inclined with respect to the first opening and the second opening.

Third Aspect

In a third aspect, the elongated guide according to the second aspect has the first opening downstream from the second opening in the first direction and further has a fourth opening having a rectangular shape extending in the first direction. The fourth opening is downstream from the first opening in the first direction and is closer to the one roller than the first opening in the third direction.

Fourth Aspect

In a fourth aspect, the elongated guide in the sheet feeding device according to the second aspect or the third aspect includes a stopper in the first opening to restrict movement of the fitting portion in the first direction.

Fifth Aspect

In a fifth aspect, the sheet feeding device according to any one of the first to fourth aspects further includes another contact-separation mechanism disposed at one end of the sheet feeding device in an axial direction of said another roller and another contacted portion of the sheet tray disposed at one end of the sheet tray in the axial direction, and the contact-separation mechanism is disposed at another end of the sheet feeding device in the axial direction, and the contacted portion of the sheet tray is disposed at another end of the sheet tray in the axial direction.

Sixth Aspect

In a sixth aspect, the contact portion in the sheet feeding device according to any one of the first to fifth aspects has a first inclined face inclined with respect to an insertion and removement direction of the sheet tray, the contacted portion has a second inclined face contactable with the first inclined face of the contact portion, and the second inclined face is inclined with respect to the insertion and removement direction of the sheet tray.

Seventh Aspect

In a seventh aspect, the contacted portion in the sheet feeding device according to any one of the first to sixth aspects includes a roller contacting the contact portion.

Eighth Aspect

In an eighth aspect, the sheet feeding device according to any one of the first to seventh aspects further includes a driver to rotate the one roller, and said another roller is rotated by rotation of the one roller.

Ninth Aspect

In a ninth aspect, an image forming apparatus includes the sheet feeding device according to any one of the first to eighth aspects.

Tenth Aspect

In a tenth aspect, the conveyance roller pair in the image forming apparatus according to ninth aspect conveys the sheet in the sheet tray to the conveyance passage in the body in a conveyance direction, an insertion and removement direction of the sheet tray is in the conveyance direction, and the conveyance roller pair is downstream from the sheet tray in the conveyance direction.

The above-described embodiments are illustrative and do not limit the present disclosure. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of the embodiment and variation may be combined with each other and/or substituted for each other within the scope of the present disclosure.

The advantages achieved by the embodiments described above are examples and therefore are not limited to those described above.

Claims

1. A sheet feeding device comprising:

a body;

a sheet tray insertable to and removable from the body to store a sheet, the sheet tray including a contacted portion;

a conveyance roller pair in the body to convey the sheet stored in the sheet tray to a conveyance passage in the body, the conveyance roller pair including one roller and another roller; and

a contact-separation mechanism to contact or separate said another roller to and from the one roller, the contact-separation mechanism including: a spring; and a movable part pushed in a first direction by the spring, the movable part having: a contact portion contactable with the contacted portion of the sheet tray in response to an insertion of the sheet tray into the body to move the movable part in a second direction opposite to the first direction against the spring; and an elongated guide to change a position of said another roller in a third direction orthogonal to the first direction and the second direction with respect to the one roller according to a movement of the movable part in the first direction or the second direction.

2. The sheet feeding device according to claim 1, further comprising

a holder holding said another roller and including a fitting portion fitting to the elongated guide,

wherein the elongated guide having: a first opening having a rectangular shape extending in the first direction; a second opening shifted from the first opening in the third direction farther from the one roller than the first opening, the second opening having a rectangular shape extending in the first direction; and a third opening connecting the first opening and the second opening and inclined with respect to the first opening and the second opening.

3. The sheet feeding device according to claim 2,

wherein the first opening is downstream from the second opening in the first direction,

the elongated guide further has a fourth opening having a rectangular shape extending in the first direction,

the fourth opening is downstream from the first opening in the first direction, and

the fourth opening is closer to the one roller than the first opening in the third direction.

4. The sheet feeding device according to claim 2,

wherein the elongated guide includes a stopper in the first opening to restrict movement of the fitting portion in the first direction.

5. The sheet feeding device according to claim 1, further comprising:

another contact-separation mechanism disposed at one end of the sheet feeding device in an axial direction of said another roller; and

another contacted portion of the sheet tray disposed at one end of the sheet tray in the axial direction,

wherein the contact-separation mechanism is disposed at another end of the sheet feeding device in the axial direction, and

the contacted portion of the sheet tray is disposed at another end of the sheet tray in the axial direction.

6. The sheet feeding device according to claim 1,

wherein the contact portion has a first inclined face inclined with respect to an insertion and removement direction of the sheet tray,

the contacted portion has a second inclined face contactable with the first inclined face of the contact portion, and

the second inclined face is inclined with respect to the insertion and removement direction of the sheet tray.

7. The sheet feeding device according to claim 1,

wherein the contacted portion includes a roller contacting the contact portion.

8. The sheet feeding device according to claim 1, further comprising

a driver to rotate the one roller,

wherein said another roller is rotated by a rotation of the one roller.

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

10. The image forming apparatus according to claim 9, further comprising:

wherein the conveyance roller pair conveys the sheet in the sheet tray to the conveyance passage in the body in a conveyance direction,

an insertion and removement direction of the sheet tray is in the conveyance direction, and

the conveyance roller pair is downstream from the sheet tray in the conveyance direction.