Transfer unit and image-forming apparatus to increase a ratio of filled toner volume to toner container volume

A container to store residual transfer toner remaining on an intermediate transfer belt is disposed in a region of a transfer unit, where the region is defined by an inner circumferential surface of the intermediate transfer belt. A single conveyance member, which rotates to convey toner conveyed from an inlet toward the container, is disposed in the inside of the container. An end portion of the conveyance member that is opposite to an end portion on a side of the inlet is located in a central region of the container.

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates to a transfer unit and an electrophotographic image-forming apparatus such as a copying machine or a printer.

Description of the Related Art

A tandem image-forming apparatus known as an electrophotographic image-forming apparatus includes image-forming units that are arranged in a movement direction of a belt such as a conveyance belt or an intermediate transfer belt. Each of the image-forming units for respective colors includes a drum-shaped photosensitive member (referred to below as a photosensitive drum) that serves as an image-hearing member. A toner image of each color that is borne by the photosensitive drum for the color is transferred to a transfer material such as paper or an OHP sheet that is conveyed by a transfer-material-conveying belt, or fixed to the transfer material by a fixing unit after being transferred to the intermediate transfer belt once and subsequently transferred to the transfer material.

In some cases, a part of toner is not transferred and remains on the belt, such as a conveyance belt or an intermediate transfer belt, after the other part is transferred to the transfer material. Such residual toner is collected in a container that stores the residual toner by using a collection unit that is disposed in the image-forming apparatus. This inhibits a defective image from being produced by transferring the residual toner to a transfer material in a next image formation process.

Japanese Patent Application Laid-Open No. 2007-286371 discloses that a first conveyance member that conveys toner in a first direction and second and third conveyance members that convey the toner in a second direction perpendicular to the first direction are disposed in a container that stores collected residual toner. With this structure, the first conveyance member first conveys the residual toner in the first direction along a side of the container. Subsequently, the second and third conveyance members that are arranged at different positions in the first direction convey the residual toner in the second direction. This enables the toner to be efficiently filled in the container.

With the structure in Japanese Patent Application Laid-Open No. 2007-286371, the residual toner can be efficiently filled with respect to the volume of the container. However, since the conveyance members are disposed in the container, the volume of the toner that can be filled in the container decreases by the volume of a region that the conveyance members occupy. In recent years, there has been a need to decrease the size of an image-forming apparatus, and there has been a need to increase the ratio of the volume of filled toner to the volume of a container.

SUMMARY OF THE DISCLOSURE

According to the present disclosure, in a container to store residual toner, a conveyance member that conveys the toner is disposed, and the ratio of the volume of the filled toner to the volume of the container is increased.

According to an aspect of the present disclosure, a transfer unit disposed in an image-forming apparatus, wherein the image-forming apparatus includes an image-bearing member configured to bear a toner image, includes a belt that is movable, endless, and in contact with the image-bearing member, a collection member which is in contact with the belt and configured to collect toner remaining on the belt, a container, which is disposed in a region defined by an inner circumferential surface of the belt, which has an inlet through which the toner collected by the collection member enters the container, and which has a bottom surface on which the toner entering through the inlet is to be supported and an upper surface that is opposite to the bottom surface, and a single conveyance member which includes a conveyance portion spirally extending in a rotation axis direction and which is configured to rotate to convey the toner from the inlet in the container, wherein, in a projected view of the container on a horizontal plane in a direction orthogonal to a movement direction and a width direction, a central region of the container is located in a region in which a middle region of trisected regions of the container in the movement direction overlaps a middle region of trisected regions of the container in the width direction, and wherein the single conveyance member conveys the toner from the inlet toward the central region of the container.

Further features and aspects of the present disclosure will become apparent from the following description of example embodiments with reference to the attached drawings.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will hereinafter be described in detail by way of example with reference to the drawings. The dimensions, materials, shapes, and relative positions of components described according to the embodiments may be appropriately changed depending on the structure of an apparatus for which the present disclosure is used or various conditions. Accordingly, the scope of the present disclosure is not limited to these unless there is a specific description.

First Example Embodiment

Structure of Example Image-Forming Apparatus

FIG. 1is a schematic perspective view of the structure of an image-forming apparatus1according to the present embodiment.FIG. 2is a schematic sectional view of an internal structure of the image-forming apparatus1. The image-forming apparatus1according to the present embodiment is a so-called tandem image-forming apparatus that includes image-forming units PY, PM, PC, and PK. The first image-forming unit PY uses yellow (Y) toner, the second image-forming unit PM uses magenta (M) toner, the third image-forming unit PC uses cyan C toner, and the fourth image-forming unit PK uses black (Bk) toner to form an image.

The image-forming apparatus1operates in a process cartridge method. The image-forming units PY, PM, PC, and PK are provided as process cartridges and can be attached to and detached from an apparatus body2. The process cartridges are detached or attached with a door3of the image-forming apparatus1opened. Below door3is a sheet feed cassette10. As illustrated inFIG. 2, the four image-forming units PY, PM, PC, and PK are lined up at regular intervals. Many parts of the structure of each image-forming unit PY, PM, PC, and PK are substantially common to each other except for the color of the toner that is stored therein. Accordingly, provided that it is not necessary to distinguish these components, the final reference characters Y, M, C, and K that represent the colors for which the components are used are omitted in the following description, and the components will be collectively described.

In the following description, a surface of the image-forming apparatus1along which the door3is disposed is referred to as a front surface, and a surface opposite the front surface is referred to as a back surface. When the image-forming apparatus1is viewed in front of the front surface, the right-hand side is referred to as a drive side, and the left-hand side is referred to as a non-drive side. In the drawings, a direction from the back surface of the apparatus body2toward the front surface thereof is referred to as an X-axis direction, a direction from the non-drive side of the apparatus body2toward the drive side thereof is referred to as a Y-axis direction, and a direction from the bottom surface of the apparatus body2toward the upper surface thereof is referred to as a Z-axis direction.

As illustrated inFIG. 2, the image-forming units P are arranged parallel to the bottom surface of the apparatus body2. Each image-forming unit P includes an electrophotographic process mechanism. A rotation driving force is transmitted from a cartridge driving force transmitter, not illustrated, which is disposed in the apparatus body2. The image-forming units P include respective photosensitive drums40that serve as image-bearing members that bear toner images, respective charge units (not illustrated), and respective development units (not illustrated).

An exposure unit LS is disposed above the image-forming units P in the Z-axis direction. The exposure unit LS emits a laser beam based on image information that a controller, not illustrated, receives. The laser beam that is emitted from the exposure unit LS passes through an exposure window of each image-forming unit P and reaches the surface of each photosensitive drum40for scan exposure.

A transfer unit11is disposed below the image-forming units P in the Z-axis direction. The transfer unit11includes a movable, endless, intermediate transfer belt12, primary transfer rollers16, a drive roller13, a stretch roller17, a stretch roller15, a collection unit19, and a container18. The drive roller13rotates when a driving force is applied thereto, moves the intermediate transfer belt12in the direction of an arrow B inFIG. 2, and stretches the intermediate transfer belt12together with the stretch roller17and the stretch roller15. The collection unit19collects toner that remains on the intermediate transfer belt12. The toner that is collected by the collection unit19is stored in the container18that is disposed in a region that is defined by the inner circumferential surface of the intermediate transfer belt12.

The primary transfer rollers16serve as transfer units that transfer the toner images that are borne by the photosensitive drums40from the photosensitive drums40to the intermediate transfer belt12and are in contact with the inner circumferential surface of the intermediate transfer belt12. The primary transfer rollers16Y,16M,16C, and16K respectively face the photosensitive drums40Y,40M,40C, and40K with the intermediate transfer belt12interposed therebetween. The primary transfer rollers16extend in a direction perpendicular to the direction of the arrow B inFIG. 2, that is, in the Y-axis direction, urge the intermediate transfer belt12against the photosensitive drums40, and define primary transfer portions at which the photosensitive drums40and the intermediate transfer belt12are in contact with each other.

According to the present embodiment, each primary transfer roller16is a metal roller that has no elastic layer. The primary transfer roller16, which is a metal roller, is low in cost but carries a risk that the primary transfer roller16causes a facing component to wear because of the hardness thereof. In view of this, according to the present embodiment, as illustrated inFIG. 2, the primary transfer rollers16are shifted from the positions of the primary transfer portions at which the photosensitive drums40and the intermediate transfer belt12are in contact with each other. More specifically, the primary transfer rollers16are shifted to positions downstream of the primary transfer portions in the movement direction of the intermediate transfer belt12. The primary transfer rollers16may be shifted to positions upstream of the primary transfer portions.

The collection unit19includes a frame body19aand a cleaning blade19b(collection member) that is disposed in the frame body19aand that extends in the Y-axis direction. The cleaning blade19bextends in the direction opposite the movement direction of the intermediate transfer belt12and is in contact with the outer circumferential surface of the intermediate transfer belt12to collect the toner that remains on the intermediate transfer belt12in the frame body19a.

A secondary transfer roller14faces the drive roller13(driving rotary member) with the intermediate transfer belt12interposed therebetween. A secondary transfer portion is defined at a position at which the secondary transfer roller14and the intermediate transfer belt12are in contact with each other. A feed unit50includes a sheet feed cassette51(sheet feed cassette10inFIG. 1) that stores a transfer material S and a sheet-feeding roller52that feeds the transfer material S from the sheet feed cassette51toward the secondary transfer portion, and is disposed upstream of the secondary transfer portion in a direction in which the transfer material S is conveyed.

A fixing unit21that fixes a toner image to the transfer material S and a pair of discharge rollers22that discharges the transfer material S to which the toner image is fixed from the apparatus body2are disposed downstream of the secondary transfer portion in the movement direction of the transfer material S. The transfer material S that is discharged from the apparatus body2by using the pair of discharge rollers22is loaded on a discharge tray23.

Example Image Formation Operation

The image formation operation of the image-forming apparatus1according to the embodiment of the present disclosure will now be described. When a control unit (not illustrated) such as the controller receives an image signal, the image formation operation starts, and the photosensitive drums40and the drive roller13, for example, start rotating at a predetermined circumferential speed (process speed) due to a driving force from a drive source, not illustrated.

The surfaces of the photosensitive drums40are uniformly charged by the charge units, not illustrated, to have the same polarity as the regular charge polarity (negative polarity according to the present embodiment) of the toner. Subsequently, a laser beam is emitted from the exposure unit LS to form electrostatic latent images based on the image information. The electrostatic latent images that are formed on the photosensitive drums40are developed by using the toner that the development units, not illustrated, store. Toner images based on the image information are borne on the surfaces of the photosensitive drums40. At this time, the toner images depending on image components of yellow, magenta, cyan, and black colors are borne by the photosensitive drums40Y,40M,40C, and40K.

Subsequently, the color toner images that are borne by the photosensitive drums40reach the respective primary transfer portions with rotation of the photosensitive drums40. A voltage is applied from a power supply, not illustrated, to the primary transfer rollers16, and the color toner images that are borne by the photosensitive drums40are primarily transferred to the intermediate transfer belt12in order at the primary transfer portions. Consequently, four toner images corresponding to the target color images are formed on the intermediate transfer belt12.

Subsequently, the four toner images that are borne by the intermediate transfer belt12reach the secondary transfer portion with rotation of the intermediate transfer belt12and are secondarily transferred collectively to a surface of the transfer material S such as paper or an OHP sheet when passing through the secondary transfer portion. At this time, a voltage of the polarity opposite the regular charge polarity of the toner is applied from a secondary transfer power supply, not illustrated, to the secondary transfer roller14.

The transfer material S that is stored in the sheet feed cassette51is fed from the sheet feed cassette51by using the sheet-feeding roller52with a predetermined timing and conveyed toward the secondary transfer portion. The transfer material S to which the four toner images are transferred at the secondary transfer portion is heated and pressed by the fixing unit21and consequently fixed to the transfer material S with the toner of the four colors melted and mixed. Subsequently, the transfer material S is discharged from the apparatus body2by using the pair of discharge rollers22and loaded on the discharge tray23that serves as a loader.

After the secondary transfer, the toner (referred to below as residual transfer toner) that remains on the intermediate transfer belt12is removed from the surface of the intermediate transfer belt12by using the collection unit19that faces the drive roller13with the intermediate transfer belt12interposed therebetween. The image-forming apparatus1according to the present embodiment forms a full-color printed image by the above operation.

The image-forming apparatus1according to the present embodiment includes the controller, not illustrated, which controls the operation of each component of the image-forming apparatus1, and a memory (not illustrated) that serves as a storage unit that stores various kinds of control information. The controller controls conveyance of the transfer material S, controls drive of the intermediate transfer belt12and the image-forming units P as the process cartridges, controls image formation, and controls malfunction detection.

Example Collection of Residual Transfer Toner with Collection Unit

After the secondary transfer, the residual transfer toner on the intermediate transfer belt12is physically scraped from the intermediate transfer belt12by using the cleaning blade19band temporally stored in the frame body19aof the collection unit19. A process of collecting the residual transfer toner by using the collection unit19will now be described.

FIG. 3Ais a schematic perspective view of the structure of the transfer unit11with the intermediate transfer belt12removed. Arrows inFIG. 3Arepresent a conveyance route for the residual transfer toner that is collected by the cleaning blade19h. InFIG. 3AandFIG. 3B, an illustration of the frame body19ais omitted to illustrate an internal structure of the collection unit19. In the frame body19a, the collection unit19includes the cleaning blade19band a conveyance member19cthat conveys the residual transfer toner scraped from the intermediate transfer belt12by using the cleaning blade19b. The conveyance member19cincludes a conveyance portion cl spirally extending in a rotation axis direction thereof and rotates when a driving force from a drive source, not illustrated, is applied thereto to convey the residual transfer toner in the direction of an arrow Sa (Y-axis direction) inFIG. 3A.

Subsequently, the residual transfer toner that is conveyed in the direction of the arrow Sa inFIG. 3Ain the frame body19ais conveyed in the direction of an arrow Sb inFIG. 3Aalong a conveyance path184near a downstream end portion in the direction in which the toner is conveyed by the conveyance member19c, in other words, adjacent to an end portion near the drive side of the transfer unit11. The conveyance path184is connected to an inlet18aof the container18. A conveyance member18ban end of which is located near the inlet18ais disposed in the container18. The conveyance member18bincludes a conveyance portion b1spirally extending in the rotation axis direction and rotates to convey the residual transfer toner that reaches the inlet18ain the direction of an arrow Sc inFIG. 3A.

FIG. 3Bschematically illustrates a mechanism for transmitting a drive force to the conveyance member18band the drive roller13disposed at the end portion near the drive side of the transfer unit11. According to the present embodiment, as illustrated inFIG. 3B, the drive of the conveyance member18band the drive of the drive roller13are connected to each other by using a drive connection member200that includes a gear201and a gear202. More specifically, the drive roller13includes a gear131at the end portion near the drive side. The conveyance member18bincludes a gear186at the end portion near the drive side. The gear131engages the gear201. The gear186engages the gear202. The drive roller13includes a shaft132. When a driving force from a drive source, not illustrated, is applied to the shaft132, and the shaft132rotates, the gear131rotates. The rotational force of the drive roller13is transmitted to the gear186via the drive connection member200as a result of the rotation of the gear131, and the conveyance member18brotates.

Example Structure of Transfer Unit and Container

FIG. 4Ais a schematic sectional view of the transfer unit11viewed from a side surface (XZ plane).FIG. 4Bis a schematic side (XZ plane) view of the structure of the transfer unit11viewed in front of the drive side. InFIG. 4B, an illustration of the intermediate transfer belt12is omitted. As illustrated inFIG. 4AandFIG. 4B, the container18according to the present embodiment is disposed in a region of the transfer unit11that is defined by the inner circumferential surface of the intermediate transfer belt12. The bottom surface of the transfer unit11and the bottom surface of the container18are substantially parallel to the bottom surface of the image-forming apparatus1.

According to the present embodiment, the container18includes an upper member18cthat forms the upper surface of the container18and a lower member18dthat forms the bottom surface of the container18in the gravity direction. The upper member18cand the lower member18dconstitute a container frame body. More specifically, the upper member18cis disposed near the primary transfer rollers16, and the lower member18dis disposed in the transfer unit11near the bottom surface of the image-forming apparatus1. The upper member18cthat has a substantially rectangular shape on the XY plane and four end portions of the lower member18dare joined to each other by ultrasonic welding, and the upper member18cand the lower member18dconsequently constitute the frame body of the container18. The upper member18cand the lower member18dmay not be secured to each other by ultrasonic welding but may be secured to each other by another welding method such as thermal welding, fastening, or a joining method with an adhesive, provided that the residual transfer toner does not leak from the container18.

As illustrated inFIG. 4A, portions of the upper member18cthat face the primary transfer rollers16Y,16M, and16C are recessed in the direction away from the positions of the primary transfer rollers16, that is, in the direction toward the lower member18d. More specifically, the upper member18chas grooved portions181Y,181M, and181C that are formed at positions below the primary transfer rollers16and that extend in the extension direction of the primary transfer rollers16. With this structure, the container18does not restrict rotation of the primary transfer rollers16, and a sufficient toner storage capacity of the container18can be ensured. The grooved portions181Y,181M, and181C of the upper member18cincrease the strength of the container18and inhibit the container frame body from deforming.

As illustrated inFIG. 4B, end portions of the primary transfer rollers16Y,16M,16C, and16K in the extension direction of the primary transfer rollers16are rotatably supported by respective primary transfer bearings162Y,162M,162C, and162K. The primary transfer bearings162Y,162M,162C, and162K are urged in the +Z direction by using springs163Y,163M,163C, and163K each of which is secured at an end thereof to the upper member18cand are supported by the upper member18cso as to be movable in the Z-axis direction.

According to the present embodiment, the primary transfer rollers16include no mechanisms for separation from the intermediate transfer belt12. That is, the primary transfer rollers16are urged by the springs163(urging members), and the intermediate transfer belt12and the photosensitive drums40are always in contact with each other. Since the transfer unit11includes no mechanisms for separating the primary transfer rollers16from the intermediate transfer belt12, the region in the transfer unit11that is used for the capacity of the container18can be enlarged as much as possible.

The stretch roller17is urged in the +X direction by a tension spring173with a bearing17ainterposed therebetween to stretch the intermediate transfer belt12. An end of the tension spring173urges the bearing17a, and the other end is supported by the upper member18c. According to the present embodiment, the intermediate transfer belt12that is stretched by the stretch roller17can be released by moving the bearing17aagainst the urging force of the tension spring173.

Example Filling of Residual Transfer Toner in Container

FIG. 5schematically illustrates the transfer unit11and the container18in a projected view on the horizontal plane (XY plane) in the direction perpendicular to the movement direction of the intermediate transfer belt12and the extension direction of the primary transfer rollers16. InFIG. 5, an illustration of the intermediate transfer belt12of the transfer unit11is omitted to illustrate the structure of the container18. The residual transfer toner that passes through the conveyance path184and that enters the container18via the inlet18ais conveyed to a substantially central portion of the container18on the XY plane by using the conveyance member18b.

As illustrated inFIG. 5, a first end portion of the conveyance member18bin the rotation axis direction of the conveyance member18bis located near the inlet18a, and a second end portion thereof is supported by a bearing183a(support portion). The bearing183ais included in the lower member18dof the container18and rotatably supports the conveyance member18b. The conveyance member18bhas a region Sb in which the conveyance portion b1is disposed and a region Sr in which the conveyance portion b1is not disposed and there is only a shaft, with respect to the rotation axis direction. An end portion Eb (end) of the conveyance portion b1opposite the inlet18ain the rotation axis direction is located at the boundary between the region Sb and the region Sr. As illustrated inFIG. 5, the rotation axis direction of the conveyance member18bis not perpendicular to the X-axis direction that coincides with the movement direction of the intermediate transfer belt12or the Y-axis direction that coincides with the extension direction of the primary transfer rollers16but intersects the X-axis direction and the Y-axis direction.

In a projected view of the container18on the XY plane, the end portion Eb is located downstream of the primary transfer roller16Y and upstream of the primary transfer roller16K in the X-axis direction that coincides with the movement direction of the intermediate transfer belt12. In other words, the end portion Eb is located between the primary transfer roller16Y and the primary transfer roller16K in the X-axis direction, more specifically, in a central region Rc of the container18between the primary transfer roller16Y and the primary transfer roller16M according to the present embodiment. The central region Rc will be described in detail later. With this structure according to the present embodiment, the residual transfer toner that enters via the inlet18ais conveyed from the inlet18atoward the end portion Eb in the container18by using the conveyance portion b1and accumulated on the substantially central portion of the container18at an end of the region Sb.

If the hearing183ais disposed near the end portion Eb in the rotation axis direction of the conveyance member18bto support the second end portion of the conveyance member18b, then a rotational slide occurs between the bearing183aand the conveyance member18bnear a region to which a strong toner conveyance force of the conveyance member18bis applied. With this structure, that is, in the case where there is no region Sr, there is a possibility that the toner is fixed at a position at which the rotational slide occurs, and that conveyance of the residual transfer toner by using the conveyance member18bis consequently less stable.

According to the present embodiment, the residual transfer toner that is conveyed by the conveyance member18bis filled in the container18while concentrically diffusing about the end portion Eb although this will be described in detail later. However, if the bearing183ais disposed near the end portion Eb, there is a possibility that the residual transfer toner does not concentrically diffuse. Accordingly, as illustrated inFIG. 5, the region Sr in which there is no spiral conveyance portion b1is preferably located between the region Sb and the bearing183a. The length of the region Sr in the rotation axis direction is freely set. As illustrated inFIG. 5, the end of the conveyance member18bmay not be located near the primary transfer roller16M on the XY plane of the container18. For example, the length of the region Sr may be longer than that inFIG. 5, and the end of the conveyance member18bmay be located near a wall surface18eon which an imaginary line extending in the rotation axis direction of the conveyance member18bintersects the container18on the XY plane.

Filling of the residual transfer toner in the container18according to the present embodiment will now be described with reference toFIG. 6AtoFIG. 6D.FIG. 6Aschematically illustrates the container18in a projected view on the XY plane before the residual transfer toner reaches the inlet18aof the container18.FIG. 6B,FIG. 6C, andFIG. 6Dschematically illustrate the residual transfer toner that is conveyed from the inlet18atoward the end portion Eb by using the rotating conveyance member18band that is filled in the container18.

According to the present embodiment, the residual transfer toner starts to be filled in a state where no residual transfer toner is stored in the container18as illustrated inFIG. 6A. When the residual transfer toner reaches the inlet18a, the residual transfer toner is conveyed toward the end portion Eb by using the rotating conveyance member18bas with a state illustrated inFIG. 6B. As illustrated inFIG. 6B, the residual transfer toner that is conveyed toward the end portion Eb in the central region Rc of the container18by using the rotating conveyance member18bis accumulated with the end portion Eb centered and filled in the container18while concentrically spreading.

One-dot chain lines inFIG. 6AandFIG. 6Btrisect the container18in the X-axis direction that coincides with the movement direction of the intermediate transfer belt12and in the Y-axis direction that coincides with the width direction of the intermediate transfer belt12. In this way, as illustrated inFIG. 6AandFIG. 6B, the container18can be substantially equally divided into nine regions on the XY plane. According to the present embodiment, the end portion Eb of the conveyance member18bis located in the central region Rc of the nine divided regions. The central region Rc corresponds to a region in which a middle region of trisected regions of the container18in the X-axis direction overlaps a middle region of trisected regions of the container18in the Y-axis direction. The position of the end portion Eb will be described in detail later.

As illustrated inFIG. 6C, the residual transfer toner is continuously conveyed toward the end portion Eb by using the rotating conveyance member18b, continues to spread concentrically, and is filled. After the state inFIG. 6C, the residual transfer toner is further filled, and, as illustrated inFIG. 6D, the residual transfer toner that concentrically spreads reaches four wall surfaces of the upper member18chaving a substantially rectangular shape, and the container18is filled with the residual transfer toner. According to the present embodiment, the bottom surface of the container18is substantially parallel to the bottom surface of the image-forming apparatus1. In other words, the lower member18dis substantially parallel to the installation surface of the image-forming apparatus1. With this structure, the residual transfer toner that concentrically diffuses in the container18almost simultaneously reaches the four wall surfaces of the container18, which is preferable for filling efficiency.

FIG. 7illustrates a structure in a comparative example against the present embodiment, in which an end portion Ebx of a region Sbx of a conveyance member18bxis nearer than the position of the end portion Eb according to the present embodiment to the inlet18ain the rotation axis direction. In other words, in the comparative example, the end portion Ebx is not located in the central region Rc. In the structure in the comparative example, the end portion Ebx is located upstream of the primary transfer roller16Y in the X-axis direction that coincides with the movement direction of the intermediate transfer belt12and nearer than the primary transfer roller16K to the drive roller13, although this is not illustrated. In the following description, components in the comparative example that are substantially the same as those according to the present embodiment are designated by reference characters like to those according to the present embodiment.

The conveyance member18bxincludes a conveyance portion blx spirally extending in the rotation axis direction and rotates to convey the residual transfer toner that reaches the inlet18ain the direction of an arrow Sc (FIG. 3A). In the structure in the comparative example, as illustrated inFIG. 7, the residual transfer toner concentrically diffuses in the container18with an end of the region Sbx centered, that is, with the end portion Ebx of the conveyance member18bxcentered as in the present embodiment. In the structure in the comparative example, however, the end portion Ebx is located upstream of the primary transfer roller16Y, that is, nearer than a substantially central portion of the container18to the inlet18a, and the diffusing residual transfer toner first reaches two wall surfaces of the upper member18cnear the inlet18a. In the case where the residual transfer toner is continuously conveyed after a state in FTG.7, it is difficult for the residual transfer toner to further spread concentrically because the residual transfer toner that is concentric has been partly reached the wall surfaces, and there is a possibility that the torque of the conveyance member18bxincreases, or the container18deforms.

With the structure in the comparative example, the residual transfer toner can thus concentrically diffuse by using the single conveyance member18bx. However, even when the residual transfer toner is continuously conveyed by using the rotating conveyance member18bxafter the state inFIG. 7, the residual transfer toner does not further diffuse concentrically. Accordingly, the filling efficiency of the residual transfer toner in the comparative example is lower than that according to the present embodiment. In the case where the end portion Eb is located outside the central region Rc in a region opposite the inlet18ain the rotation axis direction of the conveyance member18bx, the filling efficiency decreases for the same reason. For this reason, according to the present embodiment, the end portion Eb is located in the central region Rc of the container18to efficiently fill the residual transfer toner in the container18.

In the positional relationship between the transfer unit11and the container18according to the present embodiment, as illustrated inFIG. 5andFIG. 6A, the central region Rc of the container18is located downstream of the primary transfer roller16Y and upstream of the primary transfer roller16C in the movement direction of the intermediate transfer belt12. Locating the end portion Eb in the central region Rc enables the ratio of the filled residual transfer toner to be increased as described above. Locating the end portion Eb near the center of the central region Rc as much as possible enables the ratio of the filled residual transfer toner to be further increased. That is, regarding the arrangement of the primary transfer rollers16of the image-forming apparatus1according to the present embodiment, the end portion Eb is located in the central region Rc between the primary transfer roller16Y and the primary transfer roller16M in the movement direction of the intermediate transfer belt12, and this enables the filling efficiency to be further improved.

According to the present embodiment, the central region Rc of the container18that is disposed in the region that is defined by the inner circumferential surface of the intermediate transfer belt12of the transfer unit11is located between the primary transfer rollers16Y and16M. The arrangement of the primary transfer rollers16in the movement direction (X-axis direction) of the intermediate transfer belt12is appropriately determined depending on the positions of the photosensitive drums40. The arrangement of the photosensitive drums40in the X-axis direction is appropriately determined based on the arrangement of the components of the image-forming apparatus1. That is, in some cases, the positions of the primary transfer rollers16in the X-axis direction differ from positions illustrated in the figures according to the present embodiment.

In this case, as illustrated inFIG. 7, the central region Rc is located near an intermediate point AE of a straight line (the imaginary line extending in the rotation axis direction of the conveyance member18bx) that connects the inlet18aand the wall surface18eto each other, and such a case is seen more frequently than the case where the central region Rc is located near the inlet18a. Accordingly, locating the end portion Eb near the intermediate point AE enables the same effects as those according to the present embodiment to be achieved. Similarly, regarding the region opposite the inlet18ain the rotation axis direction of the conveyance member18bx, locating the end portion Eb nearer than the wall surface18eto the intermediate point AE enables the same effects as those according to the present embodiment to be achieved.

According to the present embodiment, the single conveyance member18bis disposed in the container18, and the residual transfer toner that is conveyed by the conveyance member18bis concentrically filled in the container18as describe above. With this structure, the residual transfer toner can be efficiently filled even when there is only the single conveyance member18b. Accordingly, it is not necessary to dispose multiple conveyance members in the container18, and the ratio of the filled toner to the volume of the container18can be increased. In addition, since it is not necessary to dispose multiple conveyance members, the costs of the image-forming apparatus1can be decreased.

An existing structure in which multiple conveyance members are disposed in a container needs a connection for rotation of the multiple conveyance members in an internal space of the container that stores the residual transfer toner. In this case, it is necessary to provide a measure for dealing with malfunction that occurs due to a strange noise or vibration when the residual transfer toner adheres to the connection for rotation, and damage to a component due to the toner molten by frictional heat at the connection for rotation. According to the present embodiment, however, it is not necessary to provide a drive connection between the components in the container, and it is not necessary to consider the above matter. Consequently, the residual transfer toner can be stably filled in the container18with a simpler structure than an existing one.

In the case where the container18is disposed in the transfer unit11as in the present embodiment, when the transfer unit11is replaced because of the life thereof, the container18can be replaced together by replacement operation of the transfer unit11. Consequently, time that a user or a service member needs for replacement decreases, and usability can be improved. According to the present embodiment, since the container18is disposed in the transfer unit11, a space in which an existing container is disposed is eliminated, and the size of the image-forming apparatus1can be decreased.

According to the present embodiment, each primary transfer roller16is a low-cost metal roller but is not limited thereto. A conductive brush member, a conductive sheet member, or a roller member having a conductive elastic layer can be used as a transfer member. In the case of using the transfer member such as a roller having a conductive elastic layer, the transfer member may be shifted with respect to the corresponding primary transfer portion as in the present embodiment or may be disposed right below the primary transfer member.

First Example Modification

FIG. 8schematically illustrates a first modification to the present embodiment in which the lower member18dincludes a conveyance guide183b(guide portion) that covers the conveyance member18bfrom both sides in the container18.FIG. 8schematically illustrates the container18in a projected view on the XY plane as inFIG. 6AandFIG. 6B. In the following description, components according to the first modification that are substantially common to those according to the first embodiment are designated by reference characters like to those according to the first embodiment, and a description thereof is omitted.

According to the first modification, as illustrated inFIG. 8, the conveyance guide183benables the residual transfer toner to be conveyed from the inlet18atoward the central region Rc of the container18while preventing the residual transfer toner from leaking from the outside of the conveyance guide183b. Consequently, a toner conveyance loss until the residual transfer toner reaches the substantially central portion of the container18decreases, and the residual transfer toner can be more efficiently filled. Here, the inside of the conveyance guide183bmeans surfaces of the conveyance guide183bthat face the conveyance member18b, and the outside of the conveyance guide183bmeans surfaces opposite the inside.

The shape of the conveyance guide183bis not limited to the shape illustrated inFIG. 8. For example, the shape may be a tunnel shape that covers the upper surface of the conveyance member18bin the Z-axis direction, provided that the residual transfer toner does not leak from the outside of the conveyance guide183b. According to the present modification, to minimize the amount of the residual transfer toner that leaks from the outside of the conveyance guide183b, the conveyance guide183bextends from the inlet18ato the end portion Eb over the entire region Sb in the rotation axis direction of the conveyance member18bbut is not limited thereto. The conveyance guide183hmay be disposed in a part of the region Sb near the inlet18a. The conveyance guide183bmay not continuously extend in the rotation axis direction but may be divided into pieces in separated regions.

Second Example Modification

FIG. 9schematically illustrates a second modification to the present embodiment in which the lower member18dof the container18includes radial ribs183c.FIG. 9schematically illustrates the container18in a projected view on the XY plane as inFIG. 6AandFIG. 6B. In the following description, components according to the second modification that are substantially common to those according to the first embodiment are designated by reference characters like to those according to the first embodiment, and a description thereof is omitted.

According to the second modification, as illustrated inFIG. 9, the lower member18dincludes the ribs183cradially extending from the vicinity of the end portion Eb in the central region Re of the container18. The ribs183cincrease the strength of the container18and inhibit the lower member18dfrom deforming due to an increase in weight when the residual transfer toner is filled. For the container18that is disposed in the transfer unit11, this enables the container18to be inhibited from deforming in the Z-axis direction when the residual transfer toner is filled, and a part of the lower member18dcan be inhibited from coming into contact with the intermediate transfer belt12.

According to the present modification, the residual transfer toner that is concentrically filled spreads in directions including the longitudinal directions of the radial ribs183c, and the radial ribs183cdo not prevent the residual transfer toner from being filled. The radial ribs183cserve as guides when the residual transfer toner concentrically spreads, enable the residual transfer toner to uniformly spread in each direction, and improve efficiency with which the residual transfer toner is filled in the container18. The length, height, and number of the ribs183care not limited to those illustrated inFIG. 9according to the present modification but may be appropriately determined. From perspective of an increase in the strength of the lower member18d, the ribs183cpreferably extend up to the corresponding wall surfaces of the container18.

Third Example Modification

FIG. 10Aschematically illustrates a third modification to the present embodiment in which columnar members182aare disposed between the lower member18dand the upper member18cin the container18.FIG. 10Bschematically illustrates the container18in a projected view on the XY plane as inFIG. 6AtoFIG. 6D. In the following description, components according to the third modification that are substantially common to those according to the first embodiment are designated by reference characters like to those according to the first embodiment, and a description thereof is omitted.

According to the present modification, as illustrated inFIG. 10A, the columnar members182aare disposed near the central region Rc. More specifically, the columnar members182aare disposed near a substantially central portion of the upper member18cand connect the upper member18cand the lower member18dto each other. With this structure, the container18is inhibited from deforming in the Z-axis direction when the residual transfer toner is filled, and the upper member18cand the lower member18dcan be inhibited from coming into contact with the intermediate transfer belt12.

According to the present modification, as illustrated inFIG. 10B, the columnar members182aare located near the end portion Eb but are spaced from the end portion Eb. Consequently, the columnar members182ado not prevent the residual transfer toner from being filled, can support a region in the container18in which the residual transfer toner starts to be accumulated, and can efficiently inhibit the lower member18dfrom deforming. Each columnar member182apreferably has a shape that does not prevent the residual transfer toner that concentrically diffuses from spreading. As illustrated inFIG. 10B, an example of such a shape is such that a section of each columnar member182ahas a streamline shape extending in a direction that substantially coincides with a direction in which the residual transfer toner radially spreads.

According to the present modification, as illustrated inFIG. 10B, the four columnar members182aare disposed near the end portion Eb. However, the number of the columnar members182ais not limited thereto. According to the present modification, the columnar members182aand the lower member18dare secured to each other with screws but are not limited thereto. The columnar members182athat are included in the upper member18cmay be secured to the lower member18dby a welding method such as thermal welding or ultrasonic welding, or a joining method with an adhesive. According to the present modification, the upper member18cincludes the columnar members182abut is not limited thereto. The lower member18dmay include the columnar members182a, and the columnar members182amay be secured to the upper member18cby the above securing method.

Second Example Embodiment

In an example described according to the first embodiment, the container18that stores the residual transfer toner is disposed in the transfer unit11, more specifically, in the region that is defined by the inner circumferential surface of the intermediate transfer belt12. A second embodiment, however, differs from the first embodiment in that a container118that stores the residual transfer toner is not disposed inside the inner circumferential surface of the intermediate transfer belt12but is disposed outside the transfer unit11. According to the second embodiment, the other structure of the image-forming apparatus1except for the position of the container118is substantially the same as that according to the first embodiment. Accordingly, components common to those according to the first embodiment are designated by reference characters like to those according to the first embodiment, and a description there of is omitted.

FIG. 11schematically illustrates the position of the container118according to the present embodiment. As illustrated inFIG. 11, the container118is disposed below the bottom surface of a transfer unit111in the Z-axis direction. Disposing the container118outside the transfer unit111enables only the container118to be detached from the image-forming apparatus1while the ability to fill the residual transfer toner as described according to the first embodiment is maintained. That is, according to the present embodiment, the container118can be replaced regardless of the life of the transfer unit111.

According to the above embodiments, the image-forming apparatus1uses an intermediate transfer method with the intermediate transfer belt12but is not limited thereto. The use of the structure for collecting the residual transfer toner described according to the embodiments enables an image-forming apparatus1that includes a conveyance belt that conveys a transfer material P and that uses a direct transfer method to achieve the same effects as those according to the embodiments.

This application claims the benefit of Japanese Patent Application No. 2019-102858, filed May 31, 2019, and Japanese Patent Application No. 2020-076005, filed Apr. 22, 2020, which are hereby incorporated by reference herein in their entirety.