Conveyance mechanism and image forming apparatus

A conveyance mechanism includes a lower conveyance guide below an inclined conveyance path having upward or downward inclinations with which a sheet material is to be conveyed, that guides a lower surface of the sheet material; an upper conveyance guide above the inclined conveyance path, that guides an upper surface of the sheet-shaped material, the upper conveyance guide being openable and closable about a rotation shaft, which is on a side of the inclined conveyance path in a direction of a width of the inclined conveyance path to extend along the inclined conveyance path; and a first urging member to urge a portion of the upper conveyance guide away from the rotation shaft in the direction of the width of the inclined conveyance path toward the rotation shaft, the portion of the upper conveyance guide being at an upper end of the upper conveyance guide in an inclined direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

BACKGROUND

Technical Field

The present disclosure relates to a conveyance mechanism for conveying a sheet-shaped material, and an image forming apparatus including the conveyance mechanism.

Related Art

An image forming apparatus includes any one of a copying machine, a facsimile machine, a printer, and an inkjet recording apparatus, or a multifunction peripheral equipped with a combination of at least two of a copying machine, a facsimile machine, a printer, and an inkjet recording apparatus. Such an image forming apparatus is provided with conveyance mechanisms at a plurality of positions in the main body thereof to convey a sheet material, such as a recording medium, in a horizontal direction, a vertical direction, and an upward or downward inclined direction. Of the conveyance mechanisms, a conveyance mechanism in a location where a sheet material is likely to be jammed is configured to be openable and closable to facilitate jam clearing.

SUMMARY

Embodiments of the present disclosure provide an inclined conveyance mechanism including a lower conveyance guide and an upper conveyance guide. The lower conveyance guide is located below an inclined conveyance path having an upward inclination or a downward inclination with which a sheet material is to be conveyed. The lower conveyance guide guides a lower surface of the sheet-shaped material. The upper conveyance guide is located above the inclined conveyance path. The upper conveyance guide guides an upper surface of the sheet-shaped material. The upper conveyance guide is openable and closable about a rotation shaft. The rotation shaft is disposed on a side of the inclined conveyance path in a direction of a width of the inclined conveyance path so as to extend along the inclined conveyance path. The upper conveyance guide is configured such that a portion of the upper conveyance guide away from the rotation shaft in the direction of the width of the inclined conveyance path is urged toward the rotation shaft by a first urging member. The portion of the upper conveyance guide away from the rotation shaft is at an upper end of the upper conveyance guide in an inclined direction.

Other embodiments of the present disclosure provide an image forming apparatus including the inclined conveyance mechanism described above.

Other embodiments of the present disclosure provide a conveyance mechanism including a first-side conveyance guide and a second-side conveyance guide. The first-side conveyance guide is located on a first side of a conveyance path along which a sheet material is to be conveyed in a vertical direction. The first-side conveyance guide guides a first surface of the sheet-shaped material. The second-side conveyance guide is located on a second side of the conveyance path facing the first side. The second-side conveyance guide guides a second surface of the sheet material opposing the first surface. The first-side conveyance guide is openable and closable about a rotation shaft. The rotation shaft is disposed on a side of the conveyance path in a direction of a width of the conveyance path so as to extend along the conveyance path. The first-side conveyance guide is configured such that a portion of the first-side conveyance guide away from the rotation shaft in the direction of the width of the conveyance path is urged toward the rotation shaft by a first urging member. The portion of the first-side conveyance guide away from the rotation shaft is at an upper end of the first-side conveyance guide.

Other embodiments of the present disclosure provide an image forming apparatus including the conveyance mechanism described above.

DETAILED DESCRIPTION

In an image forming apparatus of the related art, in an example, a paper jam in a conveyance mechanism for conveying a sheet material in a vertical direction is cleared by opening an opening/closing door. In the example, a paper jam in a conveyance mechanism for conveying a sheet material in a horizontal direction or an inclined direction is cleared by opening an upper conveyance guide.

In the inclined conveyance mechanism for conveying a sheet material in the inclined direction, the upper conveyance guide is rotated upward about a rotation shaft disposed on one side of an inclined conveyance path to open the upper conveyance guide. Because the rotation shaft is inclined, gravity acting on the upper conveyance guide applies a force to deform a housing of the upper conveyance guide downward along the inclined conveyance path.

Such downward deformation does not occur if the housing of the upper conveyance guide has sufficient rigidity. As the rigidity of the housing increases, a mass of the housing increases, resulting in an increase in the gravity. In practice, the deformation of the housing of the upper conveyance guide is inevitable to varying degrees. Such deformation of the upper conveyance guide may cause inclination of the axis of a conveyance roller of the upper conveyance guide. As a result, a paper skew or jam may occur.

In the conveyance path for conveying a sheet material in the vertical direction, a paper skew or jam may also occur. Specifically, when a one-side conveyance guide for guiding one surface of a sheet material is opened in a horizontal direction in a way similar to that of the opening/closing door in the example described above, the one-side conveyance guide may be deformed by its own weight.

Accordingly, embodiments of the present disclosure provide a conveyance mechanism and an image forming apparatus that prevent deformation of a conveyance guide of the conveyance mechanism due to an opening or closing operation.

Inkjet Printer

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.FIG.1is a schematic view of an inkjet printer1serving as an image forming apparatus. The inkjet printer1is an example of line-head liquid discharging apparatus. The inkjet printer1includes a loading unit10for loading a sheet P to which liquid is to be applied, a pre-treatment unit20, an image forming unit (image forming device)30, a drying unit40, a sheet reversing mechanism60, and a discharge tray114. The sheet P is a recording medium, as an example of a sheet material. The image forming unit30is illustrated in an enlarged form inFIG.2. The sheet reversing mechanism60includes multiple conveyance rollers. An inclined conveyance mechanism according to this embodiment, which will be described below, is disposed between a last conveyance roller62among the multiple conveyance rollers of the sheet reversing mechanism60and the discharge tray114.

In the inkjet printer1, the pre-treatment unit20applies a pre-treatment liquid to the sheet P loaded (or supplied) from the loading unit10, as appropriate. Then, the image forming unit30applies liquid to the sheet P and performs desired printing. Then, the drying unit40dries the liquid adhering to the sheet P. After that, the sheet P is discharged to an unloading unit.

The loading unit10includes a loading tray11for receiving a plurality of sheets P, and a feeding device12for separately feeding the sheets P one by one from the loading tray11. The loading tray11includes a lower loading tray11A and an upper loading tray11B. The feeding device12includes feeding devices12A and12B. The sheet P fed from the loading unit10is supplied to the pre-treatment unit20. The pre-treatment unit20includes an application unit21. The application unit21is a treatment liquid applying unit for applying a treatment liquid to a printing surface of the sheet P. In an example, the treatment liquid has the operational effect of aggregating a coloring material of ink to prevent set-off.

As illustrated inFIG.2, the image forming unit30includes a conveyance drum31and a droplet discharger32. The conveyance drum31is a supporting member (rotary body) that rotates while supporting the sheet P on a peripheral surface thereof. The droplet discharger32discharges liquid onto the sheet P supported on the conveyance drum31. The image forming unit30further includes a transfer cylinder34and a delivery cylinder35. The transfer cylinder34receives the sheet P delivered from the pre-treatment unit20and transfers the sheet P to the conveyance drum31. The delivery cylinder35receives the sheet P conveyed by the conveyance drum31and delivers the sheet P to the drying unit40.

The conveyance drum31and the transfer cylinder34are coupled to each other by gears, and the conveyance drum31and the delivery cylinder35are coupled to each other by gears. The conveyance drum31, the transfer cylinder34, and the delivery cylinder35are each provided with a gripper. The sheet P is conveyed between the transfer cylinder34and the conveyance drum31and between the conveyance drum31and the delivery cylinder35while being sequentially held by the respective grippers.

The transfer cylinder34includes a gripper (or sheet gripper) to grip a leading end of the sheet P conveyed from the pre-treatment unit20to the image forming unit30. The sheet P, the leading end of which is gripped by the gripper, is conveyed as the transfer cylinder34rotates. The sheet P conveyed by the transfer cylinder34is delivered to the conveyance drum31at a position facing the conveyance drum31.

The conveyance drum31includes a gripper (or sheet gripper) on a surface of the conveyance drum31to grip the leading end of the sheet P. The conveyance drum31has multiple suction holes dispersed on a surface of the conveyance drum31. A suction unit generates suction airflows that are directed from desired suction holes among the multiple suction holes in the conveyance drum31toward the inside of the conveyance drum31. The sheet gripper of the conveyance drum31grips the leading end of the sheet P forwarded from the transfer cylinder34to the conveyance drum31. The sheet P is attracted to and supported on the conveyance drum31by the suction airflows generated by the suction unit. As the conveyance drum31rotates, the sheet P is conveyed.

The droplet discharger32includes four droplet discharge units33(33A to33D) for discharging droplets. The droplet discharge units33(33A to33D) are disposed radially at equal intervals and symmetrically inFIG.1along an upper portion of the outer periphery of the conveyance drum31.

The droplet discharge units33are each a functional component having a nozzle from which liquid is to be discharged and ejected. The liquid to be discharged is not limited as long as the liquid has viscosity or surface tension enough to be discharged from a head of each of the droplet discharge units33. In one example, preferably, the viscosity of the liquid is not greater than 30 mPa·s under ordinary temperature and ordinary pressure or by heating or cooling.

The droplet discharge unit33A is configured to discharge a liquid of cyan (C). The droplet discharge unit33B is configured to discharge a liquid of magenta (M). The droplet discharge unit33C is configured to discharge a liquid of yellow (Y). The droplet discharge unit33D is configured to discharge a liquid of black (K). The droplet discharger32may also include a droplet discharge unit configured to discharge a liquid of a special color such as white, gold, or silver.

A discharge operation of each of the droplet discharge units33of the droplet discharger32is controlled by a drive signal corresponding to print information. When the sheet P supported on the conveyance drum31passes through a region facing the droplet discharger32, the liquids of the respective colors are discharged from the corresponding droplet discharge units33toward the sheet P, and an image corresponding to the print information is printed on the sheet P.

The sheet P to which the liquids are applied by the droplet discharger32is transferred from the conveyance drum31to the delivery cylinder35. The sheet P received by the delivery cylinder35is transferred to a conveyance mechanism41and transported to the drying unit (heating unit)40. The drying unit40dries the liquids applied to the sheet P by the image forming unit30. The drying of the liquids allows evaporation of the liquid components such as water in the liquids, and fixes colorants contained in the liquids on the sheet P. Further, curling of the sheet P is reduced.

The sheet reversing mechanism60reverses the sheet P, which has passed through the drying unit40, in a switchback manner to perform double-sided printing. The reversed sheet P is fed back to a point located upstream of the transfer cylinder34through a conveyance path61of the image forming unit30. The sheets P conveyed through the sheet reversing mechanism60are sequentially stacked on one another and held on the discharge tray114.

Inclined Conveyance Mechanism

The inclined conveyance mechanism is coupled downstream of the last conveyance roller62of the sheet reversing mechanism60, as illustrated inFIGS.3A and3B. The inclined conveyance mechanism forms an inclined conveyance path having an upward inclination θ.

The inclined conveyance mechanism includes a lower conveyance guide110and an upper conveyance guide120. The lower conveyance guide110is located below the inclined conveyance path and guides a lower surface of the sheet P. The upper conveyance guide120is located above the inclined conveyance path and guides an upper surface of the sheet P. A drive-side conveyance roller111is disposed on a lower surface of the upper conveyance guide120to convey the sheet P.

An idler-side conveyance roller paired with the drive-side conveyance roller111is disposed on an upper surface of the lower conveyance guide110. The inclined conveyance mechanism further includes a pair of inlet-side conveyance rollers113in a right portion (i.e., at an inlet) thereof, and a pair of discharge rollers112in a left portion (i.e., at an outlet) thereof.

As illustrated inFIGS.3C and4, the upper conveyance guide120is openable and closable about a rotation shaft S. The rotation shaft S is disposed on one side of the inclined conveyance path in the direction of the width of the inclined conveyance path so as to extend along the inclined conveyance path. As illustrated inFIG.4, the rotation shaft S has a pair of upper and lower hinges H1and H2secured to a side plate130of the inclined conveyance mechanism. Referring toFIG.3C, the upper conveyance guide120is rotated (opened) about the rotation shaft S from a position indicated by a phantom line to a position indicated by a solid line. As a result, the upper conveyance guide120can be opened at a height h inFIG.3Bto form a paper-jam clearing area J illustrated inFIG.3C.

As illustrated inFIGS.3C and4, the upper conveyance guide120is configured such that a portion thereof away from the rotation shaft S is urged by a gas spring140in a direction in which the upper conveyance guide120is to be opened. In an example, the gas spring140is a second urging member. The gas spring140can reduce the force with which the upper conveyance guide120is lifted and opened for paper-jam clearing, and can hold the upper conveyance guide120in an opened state (free stop).

As illustrated inFIG.4, the gas spring140may be attached to an upper end of the upper conveyance guide120in an inclined direction. In other words, the gas spring140may be attached to an end of the upper conveyance guide120on the side of the inclined conveyance path facing the side on which the rotation shaft S is disposed in the direction of the width of the inclined conveyance path. The attached gas spring140makes it possible to ensure that the paper-jam clearing area J illustrated inFIG.3Cis wide in the left-right direction. Further, the gas spring140, which is disposed away from the rotation shaft S as much as possible, can reduce the lifting force of the upper conveyance guide120. As a result, the diameter and cost of the gas spring140can be reduced, and the upper conveyance guide120can be prevented from being deformed due to lifting.

A proximal end of the main body of the gas spring140is pivotally mounted to an upper end bracket122of one of a pair of left and right reinforcing ribs121inFIG.4. The pair of left and right reinforcing ribs121is disposed on an upper surface of the upper conveyance guide120. A distal end of a rod of the gas spring140is pivotally mounted to a support150. The support150is fixedly disposed in a lower portion of a side plate opposing the side plate130.

Forces Acting on Upper Conveyance Guide

Forces acting on the upper conveyance guide120in an opened state will be described with reference toFIGS.5A and5B. InFIGS.5A and5B, a phantom line indicates the upper conveyance guide120in the closed position. When the upper conveyance guide120is in the closed position, the sheet P is conveyed along the inclined conveyance path.

Upon the occurrence of a paper jam, the upper conveyance guide120is lifted to a position indicated by a solid line inFIGS.5A and5Bto clear the paper jam. Specifically, the upper conveyance guide120is rotated upward about the rotation shaft S.

At the rotation position indicated by the solid line inFIGS.5A and5B, as illustrated inFIG.5B, the gravity mg and a moment M1act on the rotation shaft S, where m is the mass of the upper conveyance guide120and g is gravitational acceleration. The moment M1is a rotational moment about the rotation shaft S caused by a component force F1(seeFIG.6A) of the gravity mg.

As illustrated inFIG.6A, the gravity mg acting on the upper conveyance guide120can be divided into a force F1perpendicular to the inclined conveyance path (a component force normal to the drive-side conveyance roller111) and a force F2parallel to the inclined conveyance path (a component force tangent to the drive-side conveyance roller111). The force F2acts in a direction in which a housing of the upper conveyance guide120is deformed downward along the inclined conveyance path.

The housing of the upper conveyance guide120is not deformed by the force F2if the housing has sufficient rigidity. As the rigidity of the housing increases, the mass of the housing increases, resulting in an increase in the gravity mg. Thus, the deformation of the housing of the upper conveyance guide120is actually inevitable to varying degrees. Such deformation of the upper conveyance guide120may cause a downward shift (or inclination) of the position of the drive-side conveyance roller111(a position on the side of the upper conveyance guide120farther from the rotation shaft S) in a manner indicated by a broken line and a solid line inFIG.6B. As a result, a paper skew or jam may occur.

Accordingly, this embodiment provides a tension spring160, as illustrated inFIGS.7A and7B. In an example, the tension spring160is a first urging member. The tension spring160contracts with the opening of the upper conveyance guide120from a first opened state illustrated inFIG.7Ato a second opened state illustrated inFIG.7B.

The tension spring160can prevent deformation of the housing of the upper conveyance guide120or inclination of the drive-side conveyance roller111, which will be described below. The tension spring160is inexpensive. The inclined conveyance mechanism provided with the tension spring160can thus be implemented with low cost and low complexity.

The tension spring160is located between a bracket131disposed on an inner side surface of the side plate130and a bracket123disposed on the upper surface of the upper conveyance guide120. In paper-jam clearing with the upper conveyance guide120opened widely in the state illustrated inFIG.7Bfrom the state illustrated inFIG.7A, the tension spring160approaches the rotation shaft S in plan view (as viewed from an arrow B inFIG.7B), and a component force F3sin θ of a tensile force F3of the tension spring160acts upward along the rotation shaft S, where θ represents the angle of inclination of the tension spring160.

InFIG.7B, the component force F3sin θ is directed downward for convenience of illustration. Since the rotation shaft S is inclined away from the viewer ofFIG.7B, the component force F3sin θ of the tensile force F3acts upward along the rotation shaft S. The component force F3sin θ acting upward is balanced with the component force F2(FIG.6A) of the gravity mg acting on the upper conveyance guide120, thereby preventing deformation of the housing of the upper conveyance guide120or inclination of the drive-side conveyance roller111.

Further, a rotational moment M1or M1′ about the rotation shaft S acts on the upper conveyance guide120. The rotational moments M1and M1′ are generated by the gravity mg acting on the upper conveyance guide120. As the center of gravity of the upper conveyance guide120horizontally approaches the rotation shaft S, the rotational moment decreases from the rotational moment M1to the rotational moment M1′.

In terms of a reduction in the diameter and cost of the gas spring140, it is not preferable that the rotational moment M1or M1′ is supported by the gas spring140alone. In this embodiment, a component force F3cos θ acting on the upper conveyance guide120illustrated inFIG.7Bis used to generate a rotational moment M2(FIG.8) opposite in direction to the rotational moments M1and M1′.

The rotational moment M2can reduce the load on the gas spring140, resulting in a reduction in the diameter and cost of the gas spring140. The reduction in the load on the gas spring140can prevent deformation of the upper conveyance guide120.

While the present disclosure has been described in detail with reference to an embodiment, the present disclosure is not limited to the embodiment and may be modified in various ways without departing from the spirit and scope of the present disclosure. For example, while the embodiment described above relates to an inclined conveyance mechanism having an upward inclination, another embodiment of the present disclosure may provide an inclined conveyance mechanism having a downward inclination.

Still another embodiment of the present disclosure may provide a conveyance mechanism for conveying the sheets P in a vertical direction. In this embodiment, a one-side conveyance guide disposed on one side of a vertical conveyance path and typically disposed inside an opening/closing door is configured such that a portion thereof that is away from the rotation shaft S in the direction of the width of the vertical conveyance path and that is at an upper end of the one-side conveyance guide is urged toward the rotation shaft S by a tension spring serving as a first urging member.

The one-side conveyance guide is opened and closed in the horizontal direction about the rotation shaft S. Such a one-side conveyance guide is less likely to include the gas spring140for free stop. In an example, the one-side conveyance guide may include a second urging member, such as the gas spring140, to open the one-side conveyance guide in a pop-up manner.