Image forming apparatus having movable shutter member

An image forming apparatus includes an apparatus body, a photosensitive member unit including a photosensitive member on which an electrostatic latent image is formed, and a developing unit including a developer carrying member configured to carry a developer toward a position for developing the electrostatic latent image formed on the photosensitive member with the developer. A moving mechanism moves a shutter member from a shielding position to an open position in conjunction with pressurization of the developing unit mounted to the apparatus body in a pressurizing direction so that a transition is made from a state in which a developer receiving portion is shielded to a state in which the developer receiving portion is opened after the developing unit is guided in a mounting direction and then mounted to the apparatus body.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an image forming apparatus such as a copying machine, printer, and facsimile apparatus that employ an electrophotographic process or electrostatic recording process.

Description of the Related Art

An image forming apparatus employing an electrophotographic process includes a developing device that is configured to develop an electrostatic image formed on an image bearing member using a developer. The developing device may be made detachable so as to be inserted or extracted with respect to an apparatus body of the image forming apparatus for replacement or the like (Japanese Patent Application Laid-Open No. 2009-210966).

This developing device is provided with a replenishment port that is adapted to receive a developer supplied from a replenishing device. When the developing device is removed from the apparatus body, this replenishment port is closed by a shutter member.

There is a configuration in which the developing device is moved to a position for image forming after being mounted in the image forming apparatus. When a shutter is employed for the configuration, there is the following problem. When the developing device is mounted in the image forming apparatus, the shutter is released while a distance between the replenishment port of the developing device and a replenishment port of the image forming apparatus is large. As a result, the shutter cannot function sufficiently.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an image forming apparatus for which a timing of opening/closing a shutter for opening/closing a replenishment port is optimized with a simple configuration, the image forming apparatus employing a configuration in which a developing device is moved in the image forming apparatus.

Another objective of the present invention is to provide an image forming apparatus including: an image bearing member; a developing device configured to develop an electrostatic image formed on the image bearing member with a developer; a replenishing portion configured to replenish the developer to the developing device; a replenishment port disposed in the developing device and configured to receive the developer replenished from the replenishing portion; a shutter member disposed in the developing device and configured to open and close the replenishment port; a separate/approach mechanism configured to move the developing device to a first position for forming an image and to a second position farther than the first position from the image bearing member; and a moving mechanism configured to move the shutter member from a closed position to an opened position in conjunction with a movement of the developing device from the second position to the first position by the separate/approach mechanism, the shutter member blocking the replenishment port at the closed position, and the shutter member releasing the replenishment port at the opened position.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an image forming apparatus according to the present invention will be described more in detail with reference to the accompanying drawings.

1. Schematic Configuration of Image Forming Apparatus

FIG. 1is a perspective view illustrating a front side, a right side, and an upper side of an image forming apparatus100. InFIG. 1, the image forming apparatus100is illustrated in a situation in which a front cover1provided on a front side of an apparatus body100A is opened. The image forming apparatus100further includes an inner cover2and four small covers3, andFIG. 2is a perspective view of the image forming apparatus100illustrating a disposition of units laying inside the apparatus body100A by drawing the inner cover2, the four small covers3, and a frame body illustrated inFIG. 1partially in perspective.

In the image forming apparatus100, the term “front” refers to one end side in a rotation axis direction of a photosensitive drum210. An operator normally performs attaching/detaching operation of a developing unit220from the front side. The term “back” refers to the other end side of the photosensitive drum210in the rotation axis direction. The terms “left” and “right” respectively refer to the right and the left when the image forming apparatus100is viewed from the front side. The terms “up” and “down” respectively refer to the up and the down in a gravity direction but do not respectively mean being directly above and being directly below only, but also respectively imply an upper side and a bottom side of a level surface passing through a target position or a target element. In addition, in the image forming apparatus100, a front-back direction (substantially parallel to the rotation axis direction of the photosensitive drum210) may be referred to as a “longitudinal direction”.

As illustrated inFIG. 2, the apparatus body100A includes, at a substantially center, four process units U for image forming (seeFIG. 3) arranged in a horizontal direction. The four process units U form images of respective different colors (yellow, magenta, cyan, and black). The process units U each include a drum unit270(image bearing member unit) and a developing unit220. The four process units U have substantially the same configuration except that colors of toners contained in the respective developing units220are different from one another (inFIG. 2, only the rightmost process unit U is indicated by reference numeral). Above the four process units U, an intermediate transfer belt280is disposed. The intermediate transfer belt280is made up of an endless belt and put across a plurality of support rollers (not illustrated) and looped around the support rollers at a predetermined tension. Above the intermediate transfer belt280, four toner cartridges221are arranged in the horizontal direction. The toner cartridges221contains toners with which the developing units220of the four process units U are to be replenished. The four toner cartridges221have substantially the same configuration except that colors of toners contained in the toner cartridges221are different from one another (inFIG. 2, only the right end toner cartridge221is indicated by reference numeral). On the rear side of the inside of the apparatus body100A, toner replenishing units222(seeFIG. 4) as replenishing portions are disposed in such a manner as to correspond to the respective four developing units220. The replenishing portions are configured to replenish the respective developing units220with toners from the respective toner cartridges221.

The image forming apparatus100includes laser units223(seeFIG. 4) that are disposed below the respective process units U, and a sheet cassette (not illustrated) that is disposed in a lower portion of the apparatus body100A and adapted to accommodate a sheet (a transfer material). The image forming apparatus100also includes a sheet conveying path (not illustrated) and a second transfer roller (not illustrated). The sheet conveying path is disposed in a lateral portion on the right side of the inside of the apparatus body100A. The second transfer roller forms a second transferring part by being contacted with an outer circumferential surface of the intermediate transfer belt280on a conveying path for a sheet formed by the sheet conveying path. The image forming apparatus100also includes a fixing device that is disposed on the conveying path for a sheet formed by the sheet conveying path. The image forming apparatus100also includes a tray312, on which sheets passing through the fixing device are to be stacked, in an upper portion of the apparatus body100A.

FIG. 3is a perspective view illustrating a front side, a right side, and an upper side of a process unit U.FIG. 4is a cross-sectional view of the process unit U (schematically illustrating the toner replenishing unit222and the laser unit223). The process unit U includes a drum unit270and a developing unit220. The drum unit270includes a photosensitive drum210, a charging roller224, a cleaning blade225, and a drum unit container226that is adapted to support these components. The photosensitive drum210is a photosensitive member (electrophotographic photosensitive member) of a drum type (having a cylindrical shape) and serves as an image bearing member. The developing unit220will be described later in detail. In each of the process units U, the developing unit220and the drum unit270are independent of each other and capable of being inserted into or extracted from the apparatus body100A to be detachable.

Below the process unit U, the laser unit223(exposing portion) is disposed. Thereby a relative position relationship is limited between the drum unit270and the developing unit220in a cross section that is substantially perpendicular to a rotation axis of the photosensitive drum210. That is, a laser beam from the laser unit223is applied to a bottom surface of the photosensitive drum210from below. For that reason, the developing unit220needs to be brought close to a lateral side so as not to block the laser beam. The developing unit220includes a developing roller211that is disposed facing the photosensitive drum210. For the above reason, the developing unit220is disposed in such a manner that an arrangement angle of the developing roller211with respect to a horizontal line passing through a rotation center of the photosensitive drum210(an angle formed between the rotation center of the photosensitive drum210and a straight line passing through the rotation center of the developing roller211) falls within a range of about 60 degrees.

As illustrated inFIG. 1, the image forming apparatus100includes the front cover1as a door that allows access to the inside of the apparatus body100A. The image forming apparatus100also includes the four small covers3such that each of the small covers3covers, inside the front cover1, at least a portion of an end portion on a front side of the developing unit220and the drum unit270in a corresponding process unit U. In a manner described below, the developing unit220or the drum unit270is attached to or detached from the apparatus body100A, or replaced. First, the front cover1is opened from the front side of the apparatus body100A, and then a small cover3, provided in each process unit U, is opened. Thereby, an end portion on a front side of a target unit is exposed to an outside of the apparatus body100A. Then a developing unit220or a drum unit270is inserted or extracted in an arrow G direction (front-back direction) illustrated inFIG. 2.

In the present embodiment, lifetimes of the developing unit220and the drum unit270are set to be shorter than a lifetime of the apparatus body100A. The developing unit220and the drum unit270need to be replaced when reaching the respective lifetimes. In many cases, the lifetimes are represented as the number of sheets that are output with images formed thereon. For example, assuming that the lifetime of the apparatus body100A is equivalent to 500 K of sheets, the lifetime of the drum unit270is commonly set at one equivalent to 50 K sheets. In such a case, the drum unit270needs about ten replacements within a time period represented by the lifetime of the apparatus body100A.

2. Image Forming Operation Next, an image forming operation of the image forming apparatus100will be described. When the image forming operation is started, a sheet is fed one by one from the sheet cassette provided in the lower portion of the apparatus body100A and conveyed to the second transferring part along the sheet conveying path.

In the process unit U, a surface of the photosensitive drum210is uniformly subjected to a charging process by the charging roller224. The surface subjected to the charging process is scanned with and exposed to light by the laser unit223according to image information, and an electrostatic image (electrostatic latent image) is thereby formed on the photosensitive drum210. The electrostatic image formed on the photosensitive drum210is developed (made visible) by the developing unit220using a developer, so that a toner image is formed on the photosensitive drum210. In a primary transferring part, the intermediate transfer belt280is brought into contact with the photosensitive drum210. In the primary transferring part, the toner image formed on the photosensitive drum210is primary transferred on the intermediate transfer belt280by an action of a primary transfer roller (not illustrated) disposed on an inner circumferential surface side of the intermediate transfer belt280. For example, in the formation of a full-color image, toner images of a plurality of colors are formed on the photosensitive drums210of the respective four process units U. The formed toner images of the plurality of colors are primary transferred on the intermediate transfer belt280one by one so as to be superposed on one another.

Thereafter, in a second transferring part, the toner images on the intermediate transfer belt280are secondarily transferred on the sheet by an action of the second transfer roller. The toner images subjected to the second transfer on the sheet are fixed (fused and adhered) in the fixing device, before the sheet is ejected (output) on the tray312.

3. Developing Unit

Next, referring toFIG. 3toFIGS. 6A and 6B, the developing unit220will be described more in detail.FIG. 5is a perspective view illustrating a rear side, left side, and upper side of the developing unit220.FIGS. 6A and 6Bare perspective views illustrating a vicinity of an end portion of the rear side of the developing unit220.

In the present embodiment, the developing unit220is a developing device of a two-component development system in which a two-component developer containing a toner (a non-magnetic toner particle) and a carrier (a magnetic carrier particle) is used as a developer.

As illustrated inFIG. 3andFIG. 4, the developing unit220includes a developing unit container300that is adapted to contain the developer. In the developing unit container300, the developing unit220includes the developing roller211as a developer bearing member. The developing roller211includes a hollow-cylindrical developing sleeve that is rotatable and formed of a non-magnetic material and a magnet that is disposed on the hollow of the developing sleeve so as not to rotate. The developing roller211is supported in the developing unit container300in such a manner that a portion of the developing roller211is exposed to an outside through an opening that is provided in the developing unit container300at a portion opposed to the photosensitive drum210. The rotation axis of the developing roller211and the rotation axis of the photosensitive drum210are substantially in parallel with each other. When mounted in the apparatus body100A, the developing unit220becomes able to perform developing action. In a situation of being able to perform the developing action, the developing unit220is disposed close to the drum unit270so that a distance between the developing roller211and the photosensitive drum210is a predetermined distance.

As illustrated inFIG. 4, the developing unit220includes, in the developing unit container300, a first conveying screw212and a second conveying screw213as conveying members. The first conveying screw212and the second conveying screw213convey a toner that is replenished from the toner replenishing unit222to the developing roller211.

As illustrated inFIG. 5, the developing unit220is provided with a replenishment port303as an opening, in the end portion on the rear side of the developing unit220. The replenishment port303allows a toner from the toner replenishing unit222to be brought into the developing unit container300. The replenishment port303is disposed directly above the first conveying screw212, which is one disposed the farthest from the developing roller211of the first conveying screw212and the second conveying screw213. The developing unit220is provided with a shutter member301that is adapted to open/close the replenishment port303, and a seal302that is disposed between the shutter member301and the developing unit container300, and adapted to seal a perimeter of the replenishment port303.

The inside of the developing unit container300is filled with a quantity of the developer to the extent that the first conveying screw212and the second conveying screw213are covered with the developer. Depending on how to handle the developing unit220after removing the developing unit220from the apparatus body100A, the inside of the developing unit container300may be filled with the developer in a state where the developer is deviated toward the rear side or the front side. When the developer is deviated toward the rear side, the developing unit container300is filled with the developer up to directly below the shutter member301.

The developing unit220is attached to and detached from the apparatus body100A, or replaced. Therefore, when the developing unit220is removed from the apparatus body100A, the shutter member301blocks the replenishment port303as illustrated inFIG. 6A. The developer is thus prevented from leaking out from the inner portion of the developing unit container300to the outside through the replenishment port303. Around the replenishment port303, the seal302is disposed between the shutter member301and the developing unit container300. This seal302seals a gap between the shutter member301and the developing unit container300so that the developer does not leak out from the gap. When the developing unit220is mounted in the apparatus body100A, the shutter member301moves as illustrated inFIG. 6B. The replenishment port303is then released to be exposed to the outside. To this replenishment port303, the toner replenishing unit222is coupled. The opening/closing of the shutter member301will be described later more in detail.

Next, description will be made about a separate/approach unit that is configured to cause the developing unit220to approach or separate from the photosensitive drum210.

FIG. 4illustrates a state where the developing unit220is mounted in the apparatus body100A and becomes able to perform developing action. In this state, the developing unit220is disposed close to the photosensitive drum210. Assume that a relative position relationship between the developing unit220and the photosensitive drum210is kept unchanged in a cross section that is substantially perpendicular to the rotation axis of the photosensitive drum210. Then, if the developing unit220is inserted or extracted in the front-back direction, damage such as a scratch will occur on the photosensitive drum210or the developing roller211. For that reason, attachment or detachment of the developing unit220or the drum unit270with respect to the apparatus body100A is desirably performed after the developing unit220is separated from the photosensitive drum210at a sufficient distance so that the photosensitive drum210and the developing roller211do not rub against each other.

A conceivable method is that the developing unit220and the drum unit270are integrally removed from the apparatus body100A together and then divided. However, this method significantly decreases a replacing workability of the units.

It can be said that the most reliable method for separating the developing unit220from the photosensitive drum210is to move the developing unit220in a direction of a straight line that connects a rotation center of the developing roller211and a rotation center of the photosensitive drum210inFIG. 4(toward the lower left ofFIG. 4). In the present embodiment, however, the plurality of process units U are arranged in the horizontal direction. Therefore, to move the developing unit220in a direction close to the horizontal direction, it is necessary to increase a distance between the adjacent process unit U and the developing unit220so that the developing unit220does not interfere with an adjacent process unit U. Thus, in the present embodiment, a space below the developing unit220is used to move the developing unit220in a substantially vertical direction, so as to separate the developing unit220from the photosensitive drum210. A vertical component in the moving direction of the developing unit220allows the downsizing of the image forming apparatus100.

FIGS. 7A and 7Bare front views of a process unit U when viewed from the front side.FIG. 7Billustrates a state where the developing unit220is disposed at a first position (hereafter, also referred to as an “approaching position” or “image forming position”) at which the developing unit220is close to the photosensitive drum210to be able to perform the developing action.FIG. 7Aillustrates a state where the developing unit220is disposed at a second position (hereafter, also referred to as a “separating position” or “attaching position”) at which the developing unit220is farther than at the approaching position illustrated inFIG. 7Bfrom the photosensitive drum210. In the present embodiment, in the state illustrated inFIG. 7B, the developing roller211overlaps the drum unit270when viewed from the front side. If this positional relationship is kept, the developing unit220cannot be inserted or extracted in the front-back direction. In the state illustrated inFIG. 7A, the overlap between the developing roller211and the drum unit270is released. At the same time, an adequate gap is secured between the developing unit220and the drum unit270. Therefore, in the state illustrated inFIG. 7A, the developing unit220and the drum unit270can be inserted or extracted in the front-back direction individually without damaging the photosensitive drum210or the developing roller211.

In the present embodiment, to mount the developing unit220in the apparatus body100A and bring the developing unit220into a state that allows the developing unit220to perform the developing action, the following procedure including two stages is executed. First, the developing unit220is inserted from the front side to the rear side of the apparatus body100A in the arrow G direction inFIG. 2. The developing unit220thereafter is moved upward in the substantially vertical direction indicated by an arrow H inFIG. 7B, so as to be caused to approach the photosensitive drum210.

Referring toFIG. 8, andFIGS. 9A and 9B, a separate/approach mechanism4as the separate/approach unit will be described. In the present embodiment, in each of the four process units U, a configuration and an operation of the separate/approach mechanism4are substantially the same. Therefore, description will be made about a process unit U as representative of the four process units U.FIG. 8is a perspective view illustrating a front side, left side, and upper side of the separate/approach mechanism4.FIGS. 9A and 9Bare side views of the separate/approach mechanism4when viewed from the left side (the developing unit220and a shutter member moving mechanism are also illustrated).FIG. 9Aillustrates a state where the developing unit220is disposed at the separating position illustrated inFIG. 7A.FIG. 9Billustrates a state where the developing unit220is disposed at the approaching position illustrated inFIG. 7B.

As illustrated inFIG. 8, andFIGS. 9A and 9B, the separate/approach mechanism4includes a developing rail250, a separating link260, and the small cover3. The developing rail250serving as a supporting unit is adapted to guide the insertion/extraction of the developing unit220. The developing rail250also serves as a supporting base for the developing unit220when mounting the developing unit220in the apparatus body100A. The developing rail250is provided in the apparatus body100A in such a manner as to be movable in a vertical direction and not movable in the front-back direction (a slight movement such as play is tolerated). The developing rail250is coupled with the small cover3with the separating link260serving as an acting member (developing device moving member) interposed therebetween. The separating link260is provided in the apparatus body100A in such a manner as to be movable in the front-back direction. The small cover3is held in the apparatus body100A in such a manner as to be freely pivotable about a pivot axis3A. An axis line direction of the pivot axis3A is substantially parallel to the horizontal direction and extends in a right and left direction. A cover portion3C is provided on one end side in a pivot radius direction of the small cover3and is formed so as to cover at least a portion of an end portion on the front side of the process unit U. The small cover3and the separating link260are pivotably coupled with each other by a link shaft3B that is provided at a leading edge on the other end side of the small cover3in the pivot radius direction. An axis line direction of the link shaft3B is substantially parallel to the horizontal direction and extends in the right and left directions. In this configuration, causing the small cover3to pivot can cause the separating link260to slide in the front-back direction. As seen from the above, in the present embodiment, the small cover3has a function as a cover member that is adapted to cover at least a portion of the developing unit220, as well as a function as a lever member that is adapted to cause the separate/approach mechanism4to work.

The procedure for mounting the developing unit220in the apparatus body100A and bringing the developing unit220into the state that allows the developing unit220to perform the developing action is as follows. First, as illustrated inFIG. 9A, the developing unit220is inserted from the front side to the rear side of the apparatus body100A, with the small cover3opened. At that point, the developing unit220is inserted while guided by the developing rail250, so as not to rub against the photosensitive drum210.FIG. 9Aillustrates a state where the insertion of the developing unit220into the apparatus body100A is finished. At that point, the shutter member301for blocking the replenishment port303is not closed yet.

In the state illustrated inFIG. 9A, the small cover3is caused to pivot in an arrow K direction (counterclockwise direction), the link shaft3B then pivots in the same direction, and the separating link260moves in an arrow F direction (direction from the front side toward the rear side). The separating link260includes, on an upper surface thereof, a link slope260A as a moving direction converting unit. The developing rail250includes, on a bottom surface thereof, a rail slope250A as a receiving portion. The link slope260A and the rail slope250A are disposed in such a manner as to be engaged with each other by the separating link260moving in the arrow F direction. Therefore, when the separating link260moves in the arrow F direction, the link slope260A pushes the rail slope250A upward in the substantially vertical direction, as illustrated by an arrow H inFIG. 9B. That is, the rail slope250A is moved from a concave portion that is relatively low in the separating link260to a convex portion that is relatively high in the separating link260. As a result, the developing unit220supported by the developing rail250is caused to move upward in the substantially vertical direction. This upward movement in the substantially vertical direction brings the developing unit220from the state where the developing unit220is at the separating position (FIG. 7A) into the state where the developing unit220is at the approaching position (FIG. 7B).

A procedure for removing the developing unit220from the apparatus body100A is one that is opposite to the above-described procedure. That is, in the state illustrated inFIG. 9B, the small cover3is caused to pivot in a direction reverse to the arrow K (clockwise direction), and the separating link260then moves in a direction reverse to the arrow F (direction from the rear side toward a frontward side). This movement causes, as illustrated inFIG. 9A, the rail slope250A to move downward in the substantially vertical direction while sliding on the link slope260A. That is, the rail slope250A is moved from the convex portion that is relatively high in the separating link260to the concave portion that is relatively low in the separating link260. As a result, the developing unit220is moved downward in the substantially vertical direction, so as to be caused to separate from the photosensitive drum210. The developing unit220is thereafter caused to move from the rear side to the front side along the arrow G direction inFIG. 2, so as to be extracted from the apparatus body100A.

As illustrated inFIG. 9B, when the small cover3is closed (seeFIG. 1), the developing unit220and the drum unit270are both inaccessible. The small cover3is also useful for preventing an operation error such as the insertion/extraction of the developing unit220close to the photosensitive drum210.

5. Shutter Member Moving Mechanism

Next, description will be made about a moving unit for moving the shutter member301.

The developing unit is provided with the shutter member that is adapted to open/close the replenishment port. The shutter member is often adapted to open in response to an inserting operation of the developing unit after the insertion of the developing unit into the apparatus body has been finished. Some states of the developing unit may however make the developing unit container filled with the developer to directly below the shutter member. Therefore, if the developing unit is inserted into the apparatus body with a great force, the force or a vibration occurring with the opening of the shutter member may make the developer spill out of the developing unit container in the inserting direction of the developing unit through the replenishment port to be scattered in the apparatus body. The scattered developer may be adhered to an unintended portion in an image forming region, and a poor image may occur when the scattered developer reaches a sheet. When the scattered developer is adhered to a drum unit to be replaced by a user, a hand of the user may be stained.

In contrast, in the present embodiment, as illustrated inFIG. 9A, the shutter member301is not opened yet when the insertion of the developing unit220into the apparatus body100A is finished. Therefore, a force occurring in the insertion does not cause the developer to be scattered in the apparatus body100A. In the present embodiment, as will be described below, the developing unit220is moved from the separating position to the approaching position by the separate/approach mechanism4, and the shutter member301opens in response thereto, so that the replenishment port303is released.

With reference toFIGS. 9A and 9B, the moving mechanism5serving as the moving unit will be described. In the present embodiment, in each of the four process units U, a configuration and an operation of the moving mechanism5are substantially the same. Therefore, description will be made about a process unit U as representative of the four process units U.FIGS. 6A and 6B,FIGS. 7A and 7B, andFIGS. 9A and 9Billustrate states where the developing unit220is at the respective positions.

In the present embodiment, the moving mechanism5includes a pivot link70as a shutter moving member. The pivot link70is held in the apparatus body100A on a rear side in the apparatus body100A in such a manner as to be freely pivotable about the moving member rotating shaft70A. An axis line direction of the moving member rotating shaft70A is substantially parallel to the horizontal direction and extends in a right and left direction. The pivot link70includes a link engaging portion70B that is provided on one end side in a pivot radius direction of the pivot link70and disposed in such a manner as to be engageable with an end portion260B on the rear side of the separating link260. The pivot link70includes a shutter engaging portion70C that is the other end portion of the pivot link70in the pivot radius direction and disposed in such a manner as to be engageable with the shutter member301of the developing unit220.

In the state illustrated inFIG. 9A, the link engaging portion70B of the pivot link70is not engaged with the separating link260, and the shutter engaging portion70C of the pivot link70is not engaged with the shutter member301. As long as the shutter member301can be kept closed, the link engaging portion70B and the shutter engaging portion70C may be in contact respectively with the separating link260and the shutter member301at this point. In the state illustrated inFIG. 9A, when the separating link260moves in the arrow F direction (direction from the front side to the rear side) as the small cover3pivots in the arrow K direction (counterclockwise direction), the link engaging portion70B becomes to be engaged with the separating link260. Then, as illustrated inFIG. 9B, the pivot link70pivots in an arrow J direction (clockwise direction), and the shutter engaging portion70C becomes engaged with the shutter member301. This engagement gives the shutter member301a force that causes the shutter member301to move in an arrow M direction (direction from the rear side toward the front side), so that the shutter member301opens.

In the present embodiment, a moving direction of the shutter member301intersects (substantially at right angles in the present embodiment) with the moving direction of the developing unit220between the approaching position and the separating position and is substantially parallel to a moving direction of the separating link260. In the opening of the shutter member301, the moving direction of separating link260and the moving direction of the shutter member301are opposite to each other. The pivot link70converts a force in the moving direction of the separating link260into a force in a direction of opening the shutter member301. In the present embodiment, an inserting/extracting direction (mounting direction) of the developing unit220with respect to the apparatus body100A intersects (substantially at right angles in the present embodiment) with the moving direction of the developing unit220between the approaching position and the separating position and is substantially parallel to the moving direction of the separating link260.

In the present embodiment, an operation for closing the small cover3causes the developing unit220to move in a direction of approaching the photosensitive drum210and causes the shutter member301to open. In such a case, even in a state where the developing unit container is filled with the developer up to directly below the replenishment port303, the developer does not spill out of the developing unit container300through the replenishment port303, or an amount of spilled developer is significantly reduced. The reason for this effect is as follows. That is, the shutter member301opens in conjunction with the movement of the developing unit container300along the substantially vertical direction. Therefore, even if the developing unit container300is moved with a great force, the developer in the developing unit container300is shaken only vertically. The developer thus receives no force that causes the developer to spill out of the developing unit container300. For this reason, the developer can be prevented from being scattered into the apparatus body100A through the replenishment port303. The configuration in the present embodiment is simpler than a configuration in which the shutter member is opened by a motor after the developing unit is mounted. Therefore, this configuration allows for reduction in cost and size. The configuration in the present embodiment has a better mounting workability of the developing unit220than a configuration in which the developing unit is once stopped by a braking unit immediately before the shutter member is opened.

The direction (arrow H direction) of causing the developing unit220to approach the photosensitive drum210is desirably, substantially perpendicular to a direction of a force that causes the shutter member301to open (the arrow M direction). Here, a case is considered where the direction of the force that causes the shutter member301to open is in the substantially vertical direction. For example, as such, a conceivable case is that a link with a slope is engaged with the shutter member301from below, so as to open the shutter member301. In this case, a component force of the force that causes the shutter member301to open is added to a force that causes the developing unit220to approach the photosensitive drum210. This addition of forces may consequently cause a twist that occurs in the developing unit container300or a difference in a distance between the developing roller211and the photosensitive drum210that occurs between the front and the rear of the developing unit container300in a longitudinal direction of the developing unit container300. Here, the angle at which the direction of causing the developing unit220to approach the photosensitive drum210intersects substantially at right angles with the direction of the force that causes the shutter member301to open is not limited to a case of a perfect right angle. The angle may deviate from a right angle within a range at a level of an error (e.g., about 10 degrees).

A procedure for closing the shutter member301is one that is opposite to the above-described procedure. That is, in the state illustrated inFIG. 9B, the small cover3is caused to pivot in a direction reverse to the arrow K (clockwise direction), and the separating link260then moves in a direction reverse to the arrow F (direction from the rear side toward a frontward side). This movement causes the separating link260to retract from the link engaging portion70B of the pivot link70and causes the shutter engaging portion70C of the pivot link70to retract from the shutter member301. In the present embodiment, the shutter member301is biased in a direction in which the shutter member301is closed by a spring as a biasing unit. Therefore, as the shutter engaging portion70C retracts from the shutter member301, the shutter member301is closed and brought into the state illustrated inFIG. 9A.

In the present embodiment, the image forming apparatus100includes the separate/approach unit4that is configured to move developing device220between the first position (approaching position) and the second position (separating position) farther than the first position from the image bearing member210. The image forming apparatus100also includes the moving unit5that is interlocked with the separate/approach unit4causing the developing device220to move from the separating position to the approaching position, so as to move the shutter member301from a closed position at which the shutter member301blocks the replenishment port303to an opened position at which the replenishment port303is released. This moving unit5is interlocked with the separate/approach unit4causing the developing device220to move from the approaching position to the separating position, so as to enable the shutter member301to move from the opened position to the closed position. After being moved from the approaching position to the separating position by the separate/approach unit4, the developing device220becomes able to be extracted from the apparatus body100A along a direction that intersects with a moving direction of the developing device220between the approaching position and the separating position. In addition, after being inserted into the apparatus body100A along a direction that intersects with the moving direction of the developing device220from the approaching position to the separating position, the developing device220is moved from the separating position to the approaching position by the separate/approach unit4.

In the present embodiment, the separate/approach unit4includes the acting member260that is adapted to move developing device220between the approaching position and the separating position, and the lever member3that is configured to move the acting member260. In the present embodiment, the moving unit5includes the moving member70that is adapted to be moved by the acting member260, so as to cause the shutter member301to move from the closed position to the opened position. In particular, in the present embodiment, the lever member3also serves as a cover member that is adapted to cover at least a portion of the developing device220and is movable between a shutting position and a releasing position. The cover member at the shutting position disables insertion and extraction of the developing device220with respect to the apparatus body100A. The cover member at the releasing position enables the insertion and the extraction. By moving the cover member3from the releasing position to the shutting position with the developing device220inserted into the apparatus body100A, the developing device220is caused to move from the separating position to the approaching position. In addition, by moving the cover member3from the shutting position to the releasing position with the developing device220inserted into the apparatus body100A, the developing device220is caused to move from the approaching position to the separating position. In the present embodiment, the shutter member301moves in a direction substantially perpendicular to the moving direction of the developing device220between the approaching position and the separating position, so as to open/close the replenishment port303.

As seen from the above, the present embodiment can prevent, with a simple configuration, the developer from being scattered in the apparatus body100A in the mounting of the developing unit220without decreasing the mounting workability of the developing unit220.

The present invention has been described above based on a specific embodiment. However, the present invention is not limited to the above-described embodiment.

For example, in the above-described embodiment, the developer bearing member of the developing device is disposed close to the image bearing member when the developing device is at the approaching position. The developer bearing member may however abut against the image bearing member. When the developing device is at the approaching position, a portion of the developing device may abut against the image bearing member or a unit including the image bearing member in order to maintain a distance between the developer bearing member and the image bearing member.

In the above-described embodiment, the moving direction of the developing device between the approaching position and the separating position is the substantially vertical direction. The present invention is however not limited to such an aspect. For example, the present invention is applicable even to a case where the developing device is moved in a direction of a straight line that passes through a rotation center of the image bearing member and a rotation center of the developer bearing member. In this case, for example, a change of the moving direction of the developing device can be dealt with by changing a shape of the slope formed on the separating link and the developing rail and a direction of opening/closing the small door that have been described in the above-described embodiment.

In the above-described embodiment, the image forming apparatus is a color image forming apparatus including a plurality of process units. However, the present invention is also applicable to a monochrome image forming apparatus, which includes a single process unit.

In the above-described embodiment, the image forming apparatus employs an electrophotographic process, and the image bearing member is a photosensitive member. However, when the image forming apparatus employs an electrostatic recording process, the image bearing member may be an electrostatic recording dielectric.

This application claims the benefit of Japanese Patent Application No. 2016-225549, filed Nov. 18, 2016, which is hereby incorporated by reference herein in its entirety.