Sheet conveying device and image forming apparatus including the same

A sheet conveying device includes a sheet feed tray. The sheet feed tray includes a first guide and a second guide. The first guide has a first end portion. The first end portion has a first area located in a central portion in a width direction, and a second area located closer to one end in the width direction than the first area. The first end portion is inclined such that the first area is downstream of the second area in the sheet conveying direction. The second guide has an upper end portion located downstream of the first end portion of the first guide in the sheet conveying direction and above the first end portion. The upper end portion has a third area located in a central portion in the width direction and a fourth area located closer to an end in the width direction than the third area.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2018-044584 filed on Mar. 12, 2018, the content of which is incorporated herein by reference in its entirety.

FIELD OF DISCLOSURE

Aspects disclosed herein relate to a sheet conveying device and an image forming apparatus including the sheet conveying device.

BACKGROUND

A known image forming apparatus includes a sheet conveying device with stacked upper and lower sheet feed trays.

The upper sheet feed tray includes a guide extending in a top-bottom direction or vertically and configured to guide a sheet fed from the lower tray.

SUMMARY

As the upper sheet feed tray partially defines a first path for conveying a sheet fed from the lower sheet feed tray and a second path for conveying a sheet fed from the upper sheet feed tray. As the first path and the second path join at the guide extending vertically, the second path has a gap at the guide. When a sheet fed from the upper sheet feed tray passes the gap or the guide, a trailing edge of the sheet may contact the guide with a tapping noise.

Such a gap may be left in an image forming apparatus for duplex printing, which defines a duplex path below a sheet feed tray.

Aspects disclosed herein relate to a sheet conveying device to reduce the tapping noise that may be produced by the trailing edge of a sheet and an image forming apparatus including the sheet conveying device.

According to one or more aspects disclosed herein, a sheet conveying device includes a sheet feed tray and a casing to which the sheet feed tray is detachably attached. The sheet feed tray is configured to accommodate a sheet. The sheet conveying device being configured to convey the sheet from the sheet feed tray toward the casing. The sheet feed tray includes a support portion configured to support the sheet, a first guide and a second guide. The first guide is disposed downstream of the support portion in a sheet conveying direction and configured to guide the sheet conveyed from the support portion. The first guide has a first end portion, which is a downstream end of the first guide. The first end portion has a first area and a second area. The first area is located in a central portion of the first end portion in a width direction orthogonal to the sheet conveying direction. The second area is located closer to one end, in the width direction, of the first end portion than the first area. The first end portion is inclined such that the first area is downstream of the second area in the sheet conveying direction. The second guide is configured to guide a sheet, which is conveyed from a lower level, upward. The second guide has an upper end portion. The upper end portion is located downstream of the first end portion of the first guide in the sheet conveying direction and above the first end portion. The upper end portion has a third area and a fourth area. The third area is located in a central portion of the upper end portion in the width direction. The fourth area is located closer to an end of the upper end portion in the width direction than the third area.

Thus, the sheet conveying device and the image forming apparatus including the sheet conveying device can reduce a tapping noise that may be produced by the trailing edge of a sheet.

DETAILED DESCRIPTION

An illustrative embodiment of the disclosure will be described with reference to the accompanying drawings.

In the following description, directions are defined based onFIG. 1. InFIG. 1, a right side is defined as a front or front side of the image forming apparatus1, a left side is defined as a rear or rear side of the image forming apparatus1, a side facing out of the page is defined as a left or left side of the image forming apparatus, a side facing into the page is defined as a right or right side of the image forming apparatus1, an upper side is defined as a top or upper side of the image forming apparatus1, and a lower side is defined as a bottom or lower side of the image forming apparatus1.

Overall Structure of Image Forming Apparatus

An overall structure of an image forming apparatus1will be described with reference toFIG. 1.

The image forming apparatus1includes an image forming unit2configured to form an image on a sheet S, and a sheet conveying device3configured to convey a sheet to the image forming unit2. The sheet conveying device3includes a casing4, a sheet feed tray5, a sheet feed unit6, and a discharge unit8.

The casing4is box-shaped and includes the sheet feed tray5in a lower portion of the casing4.

The casing4accommodates inside the image forming unit2, the sheet feed unit6, and a motor7configured to drive the image forming unit2.

The casing4has an upper surface defining a sheet discharge tray42. The sheet discharge tray42is recessed downward and inclined downward from the front toward the rear.

The sheet feed unit6includes a separation roller62, a separation pad44, conveying rollers63A,63B, and registration rollers65A,65B.

The casing4defines inside a conveying path P extending from the sheet feed tray5via the image forming unit2to the sheet discharge tray42. The sheet feed unit6feeds a sheet S supported on the sheet feed tray5along the conveying path P.

The sheet feed tray5is slidable in a direction parallel to an arrowed direction X from rear to front in the embodiment. The sheet feed tray5is detachably attached to the casing4.

The sheet feed tray5includes, on its bottom surface, a sheet support plate51as an example of a support portion configured to support a sheet S. The sheet support plate51is pivotable about a rotation shaft51B, which is disposed in an upstream end portion of the sheet support plate51in a sheet conveying direction in which a sheet is conveyed.

The sheet support plate51is configured to support a stack of sheets S thereon and pivot upward about the rotation shaft51B to lift downstream ends of the sheets S in the sheet conveying direction.

The sheet feed tray5includes a separation pad52for separating sheets S one by one to convey a single sheet S along the conveying path P. The separation pad52is an example of a sheet separator configured to separate one or more sheets S one by one to convey a single sheet S.

The sheet feed tray5includes a chute53configured to guide a sheet S to be conveyed to the conveying path P.

The sheet feed unit6includes a feed roller61, a separation roller62, the conveying rollers63A,63B, and the registration rollers65A,65B. The feed roller61is configured to pick up a sheet S supported on the sheet feed tray5. The separation roller62disposed downstream of the feed roller61. The separation roller62and the separation pad52are configured to contact each other to form a nip N therebetween. The conveying rollers63A,63B are disposed downstream of the chute53and configured to convey a sheet S having passed through the nip N. The registration rollers65A,65B are disposed downstream of the conveying rollers63A,63B.

The chute53includes a first guide100and a second guide200disposed downstream of the first guide100.

The first guide100and the second guide200are spaced apart from each other by a gap, which partially defines an auxiliary conveying path P1. The auxiliary conveying path P1extends upward through the gap from a bottom surface of the casing4and joins into the conveying path P upstream of the conveying rollers63A,65B in the sheet conveying direction.

In the sheet feed unit6, the feed roller61feeds a sheet S from the sheet feed tray5, the separation roller61and the separation pad62separate the sheet S from subsequent sheets S, and thus the sheet S is singly conveyed toward the conveying path P.

The sheet S conveyed by the separation roller62and the separation pad52is guided upward by the chute53having a curved shape, and passes between the conveying rollers63A,63B. The sheet S is conveyed toward the image forming unit2by the registration rollers65A,65B disposed downstream of the conveying rollers63A,63B.

The registration rollers65A,65B temporarily stop the leading end of the sheet S, and then convey the sheet S toward the transfer position in the image forming unit2at a predetermined time.

The casing4includes a casing guide66. The casing guide66is disposed downstream of the second guide200and configured to guide a sheet from the second guide200toward the registration rollers65A,65B.

The casing guide66has a second end66A, which is an upstream end in the sheet conveying direction. The second end66A is located above an upper end portion200A of the second guide200.

This structure prevents the casing guide66fixed in position to the casing4and the second guide200fixed in position to the sheet feed tray5from colliding with each other when the sheet feed tray5is slid in a horizontal direction.

The image forming unit2is disposed above the sheet feed tray5, and includes a process cartridge20configured to transfer an image on a sheet S conveyed from the sheet feed unit6, an exposure unit22configured to expose a surface of a photosensitive drum21in the process cartridge20, and a fixing unit70configured to fix the image transferred on the sheet S by the process cartridge20.

The process cartridge20includes a developing roller23, the photosensitive drum21, and a transfer roller24.

The exposure unit22includes a laser diode, a polygon mirror, a lens, and a reflecting mirror, and is configured to emit a laser beam onto a surface of the photosensitive drum21based on image data inputted in the image forming apparatus1to expose the surface.

The photosensitive drum21is disposed adjacent to the developing roller23.

The surface of the photosensitive drum21is positively and uniformly charged by a charger (not illustrated), and then exposed by the exposure unit22.

Exposed areas on the surface of the photosensitive drum21are lower in electric potential than the other areas thereon, so that an electrostatic latent image is formed on the surface of the photosensitive drum21based on the image data.

The electrostatic latent image on the surface of the photosensitive drum21is developed into a visible developer image with positively charged toner supplied from the developing roller23.

The transfer roller24is disposed facing the photosensitive drum21and receives a negative transfer bias from a bias applying member (not illustrated).

While a sheet S is nipped at a transfer position between the transfer roller24receiving the transfer bias and the photosensitive drum21carrying the developer image thereon, the developer image on the photosensitive drum21is transferred to the sheet S.

The fixing unit70includes a heat roller71and a pressure roller3.

The heat roller71is driven by a drive force from the motor7and is heated by electric power supplied from a power source (not illustrated).

The pressure roller72is disposed facing the heat roller71and rotated by the rotation of the heat roller71.

The sheet S having the developer image is conveyed to the fixing unit70, in which the sheet S is nipped and conveyed by the heat roller71and the pressure roller72, and thus the developer image is fixed onto the sheet S.

The discharge unit8includes discharge rollers81,81and is configured to discharge the sheet conveyed from the fixing unit70outside of the casing4.

More specifically, the discharge rollers81,81are configured to discharge the sheet S conveyed from the fixing unit70.

The image forming apparatus1of the embodiment may further include an additional sheet conveying device9below the casing4.

In this case, a sheet S supported on a sheet feed tray91attached to the sheet conveying device9is conveyed through the auxiliary conveying path P1and conveying path P and passes between the conveying rollers63A,63B. The sheet S is guided by the casing guide66and conveyed toward the registration rollers65A,65B.

Structure of Chute

A structure of the chute53will be described with reference toFIGS. 1 - 7.

As illustrated inFIG. 1, the chute53extends downstream from close to the separation roller62of the casing4in the sheet conveying direction. The chute53is disposed at the sheet feed tray5as a guide member for guiding a sheet S fed from the sheet feed tray5upward along a curved portion of the conveying path P.

The chute53is made up of the first guide100and the second guide200disposed downstream of the first guide100.

As illustrated inFIG. 2, the first guide100has an inclined surface101extending downstream in the sheet conveying direction (e.g., toward the front and upward in this embodiment) relative to a horizontal surface.

The first guide100includes a first end portion100A, which is a downstream (or upper) end of the inclined surface101. The first end portion100A has a first area102and a second area103. The first area102is located in a central portion of the first end portion100A in a width direction (e.g., the left-right direction in the embodiment) orthogonal to the sheet conveying direction. The second area103is located closer to one end of the first end portion100A in the width direction than the first area102is.

The first end portion100A is inclined such that the first area102is downstream of the second area103in the sheet conveying direction, and higher and closer to the front than the second area103is.

In this embodiment, the first end portion100A has another second area103located closer to the other end in the width direction, of the first end portion100A than the first area102is. The first end portion100A has a V shape such that the second areas103are inclined downstream toward the first area102in the sheet conveying direction.

The second guide200includes ribs201. The ribs201extend vertically and are spaced apart from each other in a width direction orthogonal to the sheet conveying direction.

The second guide200with the ribs201reduces contact area with a sheet S (seeFIG. 1) in comparison with that the second guide200would have no ribs or be a flat plate.

This reduces resistance to a sheet S to be conveyed and allows the second guide200to guide a sheet S passing through the first guide100toward the casing4smoothly.

As illustrated inFIG. 3, the ribs201of the second guide200have their upper ends located downstream of the first end portion100A of the first guide100in the sheet conveying direction and higher than the first end portion100A of the first guide100.

In other words, the second guide200made up of the ribs201extends vertically and is disposed such that the upper end portion200A made up of upper end portions of the ribs201is located above and downstream of the first end portion100A of the first guide100in the sheet conveying direction.

The second guide200is configured to guide, upward, a sheet S (seeFIG. 1) conveyed along the auxiliary conveying path P1from a lower level while being guided by the first guide100.

As illustrated inFIG. 6, the upper end portion200A of the second guide200is made up of the upper end portions of the ribs201. Each of the ribs201has a rounded corner near their upper end portions on the rear side.

In other words, the second guide200has a rounded corner near the upper end portion200A.

This allows the second guide200to guide a sheet S (seeFIG. 1) passing through the first guide100toward the casing4smoothly.

As illustrated inFIG. 3, the upper end portion200A of the second guide200has a third area202and fourth areas203. The third area202is located in a central portion of the upper end portion200A in the width direction. Each of the fourth areas203is located closer to an end of the upper end200in the width direction than the third area202is.

As illustrated inFIGS. 4 and 7A, the ribs201in the fourth areas203(hereinafter referred to as “end ribs201A,” which are closer to an end of the second guide200in the width direction) are located upstream of the ribs201in the third area202(hereinafter referred to as “central ribs201B” in the width direction) in the sheet conveying direction and closer to the rear than the central ribs201B are.

In this embodiment, the upper end portion200A of the second guide200is located downstream of the first end portion100A of the first guide100in the sheet conveying direction and above the first end portion100A of the first guide100. The fourth areas203in both end portions of the upper end portion200A in the width direction are located upstream of and closer to the rear than the third area202in the central portion of the upper end portion200A is.

The first end portion100A is inclined such that the first area103is downstream of the second areas102in the sheet conveying direction, and higher and closer to the front than the second areas103are. When the upstream or trailing edge of a sheet S (seeFIG. 1) passes the first guide100, both end portions of the trailing edge shift to and are supported by the second guide200in advance of the central portion of the trailing edge.

More specifically, as illustrated inFIG. 8, when a sheet S just start to pass the first guide100, the trailing edge of the sheet S is located at a position corresponding to a trailing edge of a first sheet Si indicated by a double dotted line, and both end portions of the trailing edge of the sheet S in the width direction shift to and are supported at the fourth areas203of the second guide200in advance of a central portion of the trailing edge.

Subsequently, when the central portion of the trailing edge of the sheet S passes the first guide100, the trailing edge of the sheet S is located at a position corresponding to a trailing edge of a second sheet S2indicated by a dotted line. As both end portions of the trailing edge of the sheet S in the width direction are still supported at the fourth areas203of the second guide200, stress applied to the trailing edge of the sheet S can be dispersed to reduce the tapping noise that may be produced when the trailing edge of the sheet S shifts to the second guide200.

This embodiment shows the additional sheet feed tray91, which is added below the sheet feed tray5and includes a sheet feed tray91(FIG. 1). For example, a sheet S may be conveyed from the sheet feed tray91upward toward between the first guide100and the second guide200. When the sheet S is then guided by the second guide200, as illustrated inFIG. 9, the sheet S is supported by the fourth areas203of the second guide200and thus curves relative to the width direction such that it curves downstream in the sheet conveying direction (or curved toward the front).

This provides greater rigidity in the sheet S, thus stabilizing the position of the sheet S to be conveyed.

As illustrated inFIGS. 5A, 5B, and 7B, the end ribs201A (seeFIG. 5A) in the fourth area203of the second guide200have their upper ends201A1, which are located below upper ends201B1of the central ribs201B (seeFIG. 5B) in the third area202.

In other words, the second guide200have the upper end portion200A such that the fourth areas203are upstream of the third area202in the sheet conveying direction or below the third area202.

The upper end portion200A of the second guide200is located above the first end portion100A of the first guide100. When a sheet S shifts from the first guide100to the second guide200, the leading or front end of the sheet S may collide with the second guide200, and thus bend.

In this embodiment, however, the upper end portion200A of the second guide200is shaped such that the fourth areas203at both end portions of the upper end portion200A in the width direction are located upstream of the third area202at the central portion of the upper end portion200A. Before the central portion of the leading end of the sheet S reaches the third area202of the second guide200, both end portions of the leading end of the sheet S pass the fourth areas203of the second guide200.

More specifically, as illustrated inFIGS. 10A and 10B, when a sheet S just reaches the second guide200, the leading end of the sheet S is located at a position corresponding to a leading end of a third sheet S3indicated by a double dotted line, and both end portions of the leading end of the sheet S in the width direction are in contact with the fourth areas203of the second guide200.

Thereafter, the sheet S is further conveyed and contacts the third area202of the second guide200. In this state, the leading end of the sheet S is located at a position corresponding to a leading end of a fourth sheet S4indicated by a dashed line, and both end portions of the leading end of the sheet S in the width direction pass apart from the fourth areas203of the second guide200.

This prevents the entire leading end of the sheet S from contacting the second guide200, enables a part of the leading end of the sheet S to contact the second guide200, and thus reduces the leading end of the sheet S from bending.

The sheet feed tray5includes the separation pad52(seeFIG. 1) configured to separate sheets S one by one to convey a single sheet S. As illustrated inFIG. 2, the separation pad52is disposed within an area of the first guide100corresponding to the first area102of the first end portion100A in the width direction.

This structure enables the separation pad52to separate sheets conveyed from the sheet feed tray5one by one, thus preventing a few sheets S from being conveyed toward the conveyance path P at a time.

As illustrated inFIG. 3, the second guide200includes a conveying roller63A disposed within the third area202of the upper end portion200A in the width direction.

In other words, the sheet feed tray5includes the conveying roller63A, which is disposed downstream of the separation pad52and the first end portion100A of the first guide100in the sheet conveying direction and in front of and above the separation pad52and the first end portion100A of the first guide100.

This structure allows the conveying roller63A to function as a dust removing roller to remove foreign matter such as dust from a sheet S, thus preventing foreign matter from entering the casing4. This structure also allows the first guide100to guide a sheet S to the second guide200.

Effects

The sheet conveying device3of the embodiment includes the casing4and the sheet feed tray5, which is slidable and detachably attached to the casing4. The sheet conveying device3is configured to convey a sheet S supported at the sheet feed tray5toward the casing4.

The sheet feed tray5includes the sheet support plate51, which is configured to support one or more sheets S, and the first guide100and the second guide200, which are configured to guide a sheet S conveyed from the sheet support plate51.

The first guide100has the first end portion100, which is inclined such that the first area102is downstream of the second areas103in the sheet conveying direction.

The second guide200extends vertically, has the upper end portion200A located downstream of the first guide100in the sheet conveying direction, and is configured to guide a sheet S (seeFIG. 1) conveyed from the first guide100upward.

The upper end portion200A of the second guide200is located above the first end portion100A of the first guide100. The upper end portion100A has the third area202located at the central portion, and the fourth areas203located adjacent to opposite ends of the third area202and upstream of the third area202in the sheet conveying direction.

The image forming apparatus1of the embodiment is configured as described above.

The image forming apparatus1includes the image forming unit2configured to form an image on a sheet S, and the sheet conveying device3configured to convey a sheet to the image forming unit2.

The first end portion100A of the first guide100is inclined such that the first area103is downstream of the second areas102in the sheet conveying direction, and higher and closer to the front than the second areas103are. When the upstream or trailing edge of a sheet S (seeFIG. 1) passes the first guide100, however, both end portions of the trailing edge shift to and are supported by the second guide200.

Subsequently, when a central portion of the trailing edge of the sheet S passes the first guide100, both end portions of the trailing edge of the sheet S in the width direction are supported at the second guide200, and thus stress applied to the trailing edge of the sheet S can be dispersed to reduce the tapping noise that may be produced when the trailing edge of the sheet S shifts to the second guide200.

This embodiment shows that, when a sheet S is conveyed from the sheet feed tray91of the additional sheet conveying device9upward toward between the first guide100and the second guide200, the sheet S is supported at the fourth areas203of the second guide200and thus curves relative to the width direction.

This provides greater rigidity in the sheet S, and thus stabilizes the position of the sheet S to be conveyed.

In the sheet conveying device3, the second guide200has the upper end portion200A where the fourth areas203are located below the third area202.

With this positional relationship, when a central portion of the leading end of a sheet S reaches the third area202of the second guide200, both end portions of the leading end of the sheet S pass the fourth areas203of the second guide200.

This prevents the entire leading end of the sheet S from contacting the second guide200or enables a part of the leading end of the sheet S to contact the second guide200, and thus reduces the leading end of the sheet S from bending.

In the sheet conveying device3of the embodiment, the casing4includes the casing guide66, which is disposed downstream of the second guide200and configured to guide a sheet S conveyed from the second guide200. The casing guide66has the second end66A, which is an upstream end in the sheet conveying direction. The second end66A is located above the upper end portion200A of the second guide200.

This structure prevents the casing guide66fixed in position to the casing4and the second guide200fixed in position to the sheet feed tray5from colliding with each other when the sheet feed tray5is slid in a horizontal direction.

In the sheet conveying device3of the illustrative embodiment, the second guide200has a rounded corner near the upper end portion200A.

This allows the second guide200to guide a sheet S passing through the first guide100toward the casing4smoothly.

In the sheet conveying device3, the second guide200includes the ribs201extending vertically and being spaced apart from each other in the width direction.

The second guide200with the ribs201reduces contact area with a sheet S in comparison with the second guide200without ribs.

This reduces resistance to a sheet S to be conveyed and allows the second guide200to guide a sheet S passing through the first guide100toward the casing4smoothly.

In the sheet conveying device3of the embodiment, the sheet feed tray5includes the separation pad52for separating sheets S one by one to convey a single sheet S. The separation pad52is disposed within an area of the first guide100corresponding to the first area102of the first end portion100A in the width direction.

This structure enables the separation pad52to separate sheets conveyed from the sheet feed tray5one by one, thus preventing a few sheets S from being conveyed toward the conveyance path P at a time.

In the sheet conveying device3of the embodiment, the sheet feed tray5includes the conveying roller63A, which is disposed downstream of the separation pad52and the first end portion100A of the first guide100in the sheet conveying direction and in front of and above the first end portion100A of the first guide100.

This structure allows the conveying roller63A to function as a dust removing roller to remove foreign matter such as dust from a sheet S, thus preventing foreign matter from entering the casing4. This structure also allows the first guide100to guide a sheet S to the second guide200.