Developer container and image forming apparatus including the same

A developer container (30) includes a container body (31), a movable wall (34), and a backward movement preventing mechanism (55). The container body (31) includes an inner surface (31K) defining a cylindrical internal space (31H) extending in a longitudinal direction, and a developer discharge port (319). The movable wall (34) includes an outer surface (34K) disposed slidably in close contact with the inner surface (31K) of the container body (31), and a conveying surface (340S). The conveying surface (340S) defines a storage space (31S) for developer. The movable wall (34) moves in the longitudinal direction from an initial position at one end side to the developer discharge port (319) while conveying the developer in the storage space (31S) to the developer discharge port (319). The backward movement preventing mechanism (55) prevents the movable wall (34) at the developer discharge port (319) from moving back toward the initial position.

TECHNICAL FIELD

The present invention relates to a developer container for containing developer and an image forming apparatus including the developer container.

BACKGROUND ART

Conventionally, toner containers such as one disclosed in Japanese Unexamined Patent Publication No. 2003-280344 are known as developer containers for containing developer. The toner container includes a toner discharge port and a rotary stirring member. Toner is discharged through the toner discharge port by rotation of the stirring member.

Japanese Unexamined Patent Publication No. 2009-265395 discloses a waste toner container for containing developer. The waste toner container includes a cylindrical container body having an outer circumferential portion formed with a helical groove. Collected toner is conveyed to one end of the container body along the helical groove by rotation of the container body.

In the toner container disclosed in Japanese Unexamined Patent Publication No. 2009-265395, toner is liable to remain in the region not affected by the rotational force of the conveying member, which makes it difficult to use up all the toner in the container. Further, even if the technique used for the waste container disclosed in Japanese Unexamined Patent Publication No. 2009-265395 is applied to the toner container, toner adhered to the groove will continue to rotate with the container body, so that the toner will remain in the container body. This has been a problem.

The present invention aims to provide a developer container capable of reducing the amount of developer remaining in a container body and reliably sealing a developer discharge port at the end of use of the developer container, and an image forming apparatus including the developer container.

SUMMARY

A developer container according to an aspect of the present invention comprises: a container body including an inner surface defining a cylindrical internal space extending in a longitudinal direction, and a storage space provided in the internal space for containing developer, the container body being formed with a developer discharge port in a lower part of the inner surface and communicating with the storage space for discharging developer therethrough; a movable wall disposed in the internal space of the container body, and including an outer surface disposed slidably in close contact with the inner surface, and a conveying surface defining the storage space in cooperation with the inner surface of the container body, the movable wall being movable in the longitudinal direction from an initial position set at one end side to the developer discharge port lying at the other end side of the internal space to seal the developer discharge port by the outer surface, while conveying the developer in the storage space to the developer discharge port; and a backward movement preventing mechanism configured to prevent the movable wall at the developer discharge port from moving back toward the initial position.

An image forming apparatus according to another aspect of the present invention comprises: the above-described developer container; an image carrier having a surface for allowing an electrostatic latent image to be formed thereon and operable to carry a developed image; a developing device configured to receive the developer supplied from the developer container and to supply the developer to the image carrier; and a transfer section configured to transfer the developed image from the image carrier onto a sheet.

The present invention provides a developer container capable of reducing the amount of developer remaining in a container body and reliably sealing a developer discharge port at the end of use of the developer container, and an image forming apparatus including the developer container.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.FIGS. 1 and 2are perspective views of a printer100(image forming apparatus) according to an embodiment of the present invention.FIG. 3is a schematic sectional view showing an internal structure of the printer100shown inFIGS. 1 and 2. The printer100shown inFIGS. 1 to 3, which exemplifies the image forming apparatus, is configured as a so-called monochrome printer. However, other apparatuses may alternatively be provided as an image forming apparatus in other embodiments, such as a color printer, a facsimile apparatus or a multifunctional apparatus equipped with these functions, or another type of apparatus for forming a toner image on a sheet. It should be noted that hereinafter, terms indicating directions such as “top” “bottom” “forward” “backward” “left” and “right” are intended merely for descriptive purposes, and not for limiting the principle of the image forming apparatus.

The printer100includes a housing101for housing various components that are used for forming an image on a sheet S. The housing101includes a top wall102defining the top surface of the housing101, a bottom wall103(FIG. 3) defining the bottom surface of the housing101, a main body rear wall105(FIG. 3) connecting the top wall102and the bottom wall103, and a main body front wall104located in front of the main body rear wall105. The housing101includes a main body internal space107where various components are placed. A sheet conveyance passage PP extends in the main body internal space107of the housing101, the sheet conveyance passage PP for allowing passage of a sheet S in a given conveying direction. Further, the printer100includes an opening/closing cover100C mounted on the housing101in an openable and closable manner.

The opening/closing cover100C includes a front wall upper portion104B constituting an upper portion of the main body front wall104, and a top wall front portion102B constituting a front portion of the top wall102. The opening/closing cover100C can be vertically opened and closed with unillustrated hinge shafts acting as a fulcrum, the hinge shafts being respectively disposed on a pair of arms108disposed at lateral opposite ends of the opening/closing cover100C (FIG. 2). When the opening/closing cover100C is open, the main body internal space107is exposed to the outside at the top thereof. On the other hand, when the opening/closing cover100C is closed, the main body internal space107is closed at the top thereof.

A sheet discharge section102A is disposed in a central part of the top wall102. The sheet discharge section102A includes an oblique surface sloping downward from a front end to a rear end of the top wall102. A sheet S that has been subjected to image formation in an image forming section120described later is discharged onto the sheet discharge section102A. Further, a manual feed tray104A is disposed in a vertically central part of the main body front wall104. The manual feed tray104A is vertically pivotable with a lower end thereof acting as a fulcrum (in the direction of an arrow DT shown inFIG. 3).

With reference toFIG. 3, the printer100includes a cassette110, a pickup roller112, a first sheet feeding roller113, a second sheet feeding roller114, a conveying roller115, a pair of registration rollers116, the image forming section120, and a fixing device130.

The cassette110stores sheets S therein. The cassette110includes a lift plate111. The lift plate111is tilted to lift the leading edges of the sheets S. The cassette110can be pulled out forwardly with respect to the housing101.

The pickup roller112is disposed above the leading edges of sheets S lifted by the lift plate111. The pickup roller112rotates to draw a sheet S from the cassette110.

The first sheet feeding roller113is disposed downstream of the pickup roller112and conveys a sheet S further downstream. The second sheet feeding roller114is disposed at the inner side (rear side) of the fulcrum of the manual feed tray104A and draws a sheet placed on the manual feed tray104A into the housing101.

The conveying roller115is disposed downstream of the first sheet feeding roller113and the second sheet feeding roller114in their sheet conveying direction (hereinafter, the sheet conveying direction also being simply referred to as “conveying direction”, and the downstream in the sheet conveying direction also being simply referred to as “downstream”). The conveying roller115conveys a sheet S fed by the first sheet feeding roller113or the second sheet feeding roller114further downstream.

The pair of registration rollers116functions to correct the angle of a sheet S that has been obliquely conveyed. This makes it possible to adjust the position of an image to be formed on the sheet S. The pair of registration rollers116supplies the sheet S to the image forming section120in accordance with timing of image formation to be performed by the image forming section120.

The image forming section120includes a photoconductive drum121(image carrier), a charger122, an exposure device123, a developing device20, a toner container30(developer container), a transferring roller126(transfer section), and a cleaning device127.

The photoconductive drum121is in the form of a cylinder. The photoconductive drum121has a surface to be formed with an electrostatic latent image, and carries a toner image (developed image) corresponding to the electrostatic latent image on the surface. The charger122is applied with a predetermined voltage, and charges the circumferential surface of the photoconductive drum121substantially uniformly.

The exposure device123irradiates the circumferential surface of the photoconductive drum121charged by the charger122with beams of laser light. The beams of laser light are emitted in accordance with image data output from an external device (not shown) such as a personal computer which is communicably connected to the printer100. Consequently, the circumferential surface of the photoconductive drum121is formed with an electrostatic latent image corresponding to the image data.

The developing device20supplies toner to the circumferential surface of the photoconductive drum121, the circumferential surface being formed with an electrostatic latent image. The toner container30supplies toner to the developing device20. The toner container30is detachably attached to the developing device20. The developing device20supplies the toner to the photoconductive drum121to develop (visualize) the electrostatic latent image formed on the circumferential surface of the photoconductive drum121. Consequently, the circumferential surface of the photoconductive drum121is formed with a toner image (developed image).

The transferring roller126is disposed below and opposite the photoconductive drum121across the sheet conveyance passage PP. The transferring roller126defines a transfer nip N in cooperation with the photoconductive drum121for transferring a toner image onto a sheet S.

The cleaning device127removes, after a toner image is transferred onto a sheet S from the circumferential surface of the photoconductive drum121, toner remaining on the circumferential surface.

The fixing device130is disposed downstream of the image forming section120in the conveying direction, and fixes a toner image on a sheet S. The fixing device130includes a heating roller131for melting toner on the sheet S, and a pressure roller132for bringing the sheet S into close contact with the heating roller131.

The printer100further includes a pair of conveying rollers133disposed downstream of the fixing device130, and a pair of discharge rollers134disposed downstream of the pair of conveying rollers133. A sheet S is conveyed upward by the pair of conveying rollers133to be finally discharged from the housing101by the pair of discharge rollers134. The sheet S discharged from the housing101is placed on the sheet discharge section102A, thereby resulting in a stack of sheets.

FIG. 4is a plan view showing an internal structure of the developing device20. The developing device20includes a development housing210in the form of a box having a longer dimension in a specific direction (an axial direction of a developing roller21or a left-right direction). The development housing210includes a storage space220. In the storage space220, there are disposed the developing roller21, a first stirring screw23, a second stirring screw24, and a toner supply port25. The present embodiment employs a one-component developing method and, therefore, the storage space220is filled with toner that is to be used as developer. On the other hand, in the case of a two-component developing method, a mixture of toner and carrier including a magnetic material is filled as developer. The toner is circulatively conveyed in the storage space220and successively supplied from the developing roller21to the photoconductive drum121in order to develop an electrostatic latent image.

The developing roller21is in the form of a cylinder extending in a longitudinal direction of the development housing210, and includes a sleeve constituting a circumferential portion of the developing roller21which is operable to be rotationally driven.

The storage space220of the development housing210is covered by an unillustrated top portion and divided, by a partition plate22extending in the left-right direction, into a first conveyance passage221and a second conveyance passage222having a longer dimension in the left-right direction. The partition plate22is shorter than the lateral width of the development housing210to define a first communication passage223and a second communication passage224respectively at the left and right sides of the partition plate22, the first and second communication passages223and224allowing communication between the first conveyance passage221and the second conveyance passage222. Consequently, there is a circulation passage constituted by the first conveyance passage221, the second communication passage224, the second conveyance passage222, and the first communication passage223in the storage space220. Toner is conveyed through the circulation passage counterclockwise inFIG. 4.

The toner supply port25(developer receiving port) is an opening formed in the top portion, and is disposed above and near a left end of the first conveyance passage221. The toner supply port25faces the above-mentioned circulation passage, and functions to allow replenishment toner (replenishment developer) supplied from the toner container30to flow into the storage space220.

The first stirring screw23is disposed in the first conveyance passage221. The first stirring screw23includes a first rotary shaft23a,and a first spiral blade23b(screw blade) in the form of a spiral protrusion formed on the circumferential surface of the first rotary shaft23a.The first stirring screw23is driven to rotate around the axis of the first rotary shaft23a(in the direction of an arrow R2) to convey toner in the direction of an arrow D1shown inFIG. 4. The first stirring screw23conveys toner so that the toner passes through a portion of the first conveyance passage221that faces the toner supply port25. Thus, the first stirring screw23functions to convey and mix toner having been conveyed from the second conveyance passage222with new toner flowing in from the toner supply port25in the first conveyance passage221. A first paddle23cis disposed in a downstream part of the first stirring screw23in the toner conveying direction (in the arrow D1direction). The first paddle23cis configured by a plate-like member disposed on the first rotary shaft23a.The first paddle23cis rotated with the first rotary shaft23ato deliver toner from the first conveyance passage221to the second conveyance passage222in the direction of an arrow D4shown inFIG. 4.

The second stirring screw24is disposed in the second conveyance passage222. The second stirring screw24includes a second rotary shaft24a,and a second spiral blade24bin the form of a spiral protrusion formed on the circumferential surface of the second rotary shaft24a.The second stirring screw24is driven to rotate around the axis of the second rotary shaft24a(in the direction of an arrow R1) to supply toner to the developing roller21while conveying toner in the direction of an arrow D2shown inFIG. 4. A second paddle24cis disposed in a downstream part of the second stirring screw24in the toner conveying direction (in the arrow D2direction). The second paddle24cis rotated with the second rotary shaft24ato deliver toner from the second conveyance passage222to the first conveyance passage221in the direction of an arrow D3shown inFIG. 4.

The toner container30(FIG. 3) is disposed above the toner supply port25of the development housing210. The toner container30includes a toner discharge port319(FIG. 4). The toner discharge port319is disposed at a bottom portion311(FIG. 6) of the toner container30and corresponds to the toner supply port25of the development housing20. Toner falling through the toner discharge port319passes through the toner supply port25to be supplied to the development device20.

Now, there will be described a flow of toner that is newly supplied through the toner supply port25.FIG. 5is a sectional view showing the vicinity of the toner supply port25disposed in the developing device20and the toner discharge port319disposed in the toner container30.

Replenishment toner T2being supplied through the toner discharge port319of the toner container30falls into the first conveyance passage221to be mixed with existing toner T1, and the mixture of toners T1and T2are conveyed in the arrow D1direction by the first stirring screw23. At this time, the toners T1and T2are stirred and charged.

The first stirring screw23includes a reducing paddle28(conveying ability reducing portion) disposed downstream of the toner supply port25in the toner conveying direction, the reducing paddle for partially reducing the ability of conveying toner. In the present embodiment, the reducing paddle28is configured by a plate-like member extending between a particular advancing point and a particular receding point of a turn of the first spiral blade23bof the first stirring screw23. The reducing paddle28rotates with the first rotary shaft23ato cause toner being conveyed from the upstream side of the reducing paddle28to begin to accumulate. The accumulation of toner grows up to immediately upstream of the reducing paddle28, that is, a portion where the toner supply port25faces the first conveyance passage221. As a result, a tonner accumulation portion29(developer accumulation portion) appears near the inlet of the toner supply port25.

When the amount of toner in the storage space220increases as a result of the supply of replenishment toner T2though the toner supply port25, the toner of the accumulation portion29covers (seals) the toner supply port25, which prevents further toner supply. Thereafter, as the toner of the accumulation portion29decreases due to consumption of toner in the storage space220by the developing roller21, the amount of toner covering the toner supply port25decreases such that a gap appears between the accumulation portion29and the toner supply port25. This allows new inflow of replenishment toner T2into the storage space220through the toner supply port25. As described, the present embodiment employs the volume replenishment type toner supply method in which the amount of replenishment toner to be received is adjusted according to the decrease in the amount of toner of the accumulation portion29.

Now there will be described a toner container30(developer container) according to a first embodiment of the present invention with reference toFIGS. 6 to 11.FIGS. 6 and 7are perspective views of the toner container30according to the present embodiment.FIG. 8Ais a plan view of the toner container30,FIG. 8Bis a front view of the toner container30, andFIG. 8Cis a side view of the toner container30.FIG. 9is an exploded perspective view of the toner container30.FIGS. 10A and 10Bare perspective views of a movable wall34of the toner container30.FIG. 11is a sectional view of the toner container30.

The toner container30is substantially in the form of a cylinder. The toner container30contains replenishment toner (developer). With reference toFIGS. 9 and 11, the toner container30includes a container body31(container body), a stirring disc32, a shaft33(shaft), the movable wall34, a washer35(FIG. 9), a sponge seal36, a lid37, a rotary gear38(drive transmitter), a cover39, and screws40(FIG. 9).

The container body31constitutes the body of the toner container30and is substantially in the form of a cylinder. The container body31includes an inner circumferential portion31K (inner surface) and an internal space31H (FIGS. 9 and 11). The inner circumferential portion31K is defined by the inner surface of the container body31. The internal space31H is in the form of a cylinder extending in a longitudinal direction (in a first direction, the direction of an arrow DA shown inFIGS. 6, 7, and 11) and is defined by the inner circumferential portion31K.

The container body31includes a bottom portion311, a top portion312, a front wall313(side wall), a rear wall314(side wall), a left wall315(wall portion), and a flange316. The bottom portion311constitutes the bottom of the container body31and is in the form of a half cylinder projecting downward. In other words, the bottom portion311has an arc shape in sectional view perpendicularly intersecting the first direction. The front wall313and the rear wall314are a pair of side walls standing upward on the opposite lateral ends of the bottom portion311. The top portion312is disposed above the bottom portion311to cover the internal space31H from above. The left wall315joins one end (left end) of each of the bottom portion311, the front wall313, the rear wall314, and the top portion312in the first direction, thereby covering the container body31. The internal space31H is defined by the bottom portion311, the top portion312, the front wall313, the rear wall314, and the left wall315, and also by the lid37described later. The internal space31H includes a storage space31S defined between the left wall315and the movable wall34described later. The storage space31S is a space where toner is contained in the toner container30.

As shown inFIG. 9, the container body31is open at an end thereof that is opposite to the left wall315in the first direction. The flange316defines this opening and has an outer diameter greater than that of the opposite end of the container body31in the first direction. The flange316is attached with the lid37described later.

The container body31includes a shutter317, a first guiding portion318, and a toner discharge port319(developer discharge port). The shutter317is disposed at one end of the container body31in the first direction. The shutter317can be slid in the first direction. The shutter317closes (seals) the toner discharge port319from the outside of the container body31, and exposes the toner discharge port319to the outside.

The first guiding portion318is in the form of a protrusion vertically extending on the outer surface of the left wall315. The first guiding portion318guides mounting of the toner container30into the housing101in cooperation with a second guiding portion392described later.

The toner discharge port319is an opening formed in a lower part of the inner circumferential portion31K of the container body31and communicates with the internal space31H (storage space31S). As shown inFIGS. 8B and 9, the toner discharge port319is formed at the one end of the container body31in the first direction. Further, the toner discharge port319is formed along the arc shape of the bottom portion311and having a predetermined width in the first direction. Toner contained in the storage space31S is discharged through the toner discharge port319toward the developing device20. In the present embodiment, as described above, the internal space31H of the container body31is defined by the bottom portion311, the front wall313, the rear wall314, and the top portion312. Therefore, the toner in the storage space31S concentrates at a mid-portion of the arc-shaped bottom portion311by its own weight. This allows the toner, which is conveyed by the movable wall34described later, to be efficiently discharged through the toner discharge port319.

The stirring disc32(FIGS. 9 and 11) is configured by a plate member in the form of a disc. The stirring disc32is secured to a second shaft end portion332of the shaft33described later, and rotates integrally with the shaft33. The stirring disc32is disposed along the left wall315in the storage space31S of the container body31. The stirring disc32functions to stir toner existing over the toner discharge port319.

The shaft33is disposed in the internal space31H and extends in the first direction, the shaft33being rotatably supported on the container body31and the lid37described later. The shaft33includes a first shaft end portion331, the second shaft end portion332, a male thread333(first engaging portion), and a movable wall stopper portion334.

The first shaft end portion331(FIG. 11) is defined by one end of the shaft33in the first direction. The first shaft end portion331is axially supported in a lid shaft hole37J of the lid37described later. The second shaft end portion332is defined by the other end of the shaft33in the first direction. The second shaft end portion332is axially supported in a main body bearing31J (FIG. 11) formed in the left wall315of the container body31. The male thread333is in the form of a helical ridge projecting from the outer surface of the shaft33in the internal space31H. In the present embodiment, the male thread333extends on the shaft33from a position facing the flange316to a position immediately preceding the toner discharge port319, as shown inFIG. 11. The movable wall stopper portion334is disposed downstream of the male thread333in the first direction. The movable wall stopper portion334is defined by a specific part of the shaft33, the specific part not bearing the male thread333. The movable wall stopper portion334is disposed above the toner discharge port319.

The movable wall34is disposed in the container body31and in the form of a wall extending in a direction perpendicularly intersecting the first direction. The movable wall34defines one end surface (right end surface) of the storage space31S in the first direction. The other end surface (left end surface) of the storage space31S in the first direction is defined by the left wall315and the stirring disc32. The movable wall34is moved to the toner discharge port319in the first direction from a right end side toward a left end side of the internal space31H while conveying toner contained in the storage space31S to the toner discharge port319, during a time period from the beginning of use to the end of use of the toner container30. The movable wall34can be moved only in the left direction by a motor M described later.

With reference toFIGS. 10A and 10B, the movable wall34includes a conveying wall portion340, an outer peripheral wall portion341, an inner wall seal342(sealing member), a shaft seal343(cleaning member), supply opening caps344(closing member), a movable wall shaft hole34J, and an outer circumferential portion34K (outer surface).

The conveying wall portion340defines the storage space31S in cooperation with the inner circumferential portion31K of the container body31. In particular, the conveying wall portion340includes a conveying surface340S extending in a direction perpendicular to the shaft33. The conveying surface340S conveys toner in the storage space31S by pressing it in the movement of the movable wall34. The conveying wall portion340further includes a bearing340A, toner supply openings340B (developer filling port), and a cylinder part340C. The bearing340A is formed in a substantially central part of the conveying wall portion340. The bearing340A moves in the first direction while holding the movable wall34. The above-described shaft33is inserted in the bearing340A. The toner supply openings340B are formed above the bearing340A and pass through the conveying wall portion340in the first direction. Upon attachment of the movable wall34to the container body31, the toner supply openings340B communicate with the storage space31S. Replenishment toner is filled into the storage space31S through the toner supply openings340B when the toner container30is manufactured.

The cylinder part340C projects from the surface of the conveying wall portion340that is opposite to the conveying surface340S in the first direction. The cylinder part340C constitutes a part of the bearing340A. The cylinder part340C includes a female thread340D (second engaging portion). The female thread340D is in the form of a helical ridge projecting from the inner surface of the cylinder part340C. The female thread340D functions to move the movable wall34in the first direction by engaging with the male thread333of the shaft33. At this time, an inner wall of the cylinder part340C comes into contact with an outer circumferential portion of the shaft33, whereby the position of the movable wall34is maintained. Therefore, the conveying wall portion340of the movable wall34is prevented from tilting with respect to the shaft33.

The outer peripheral wall portion341projects from an outer peripheral edge of the conveying wall portion340in a direction away from the storage space31S, namely, in the direction opposite to the moving direction of the movable wall34. The outer peripheral wall portion341faces the inner circumferential portion31K of the container body31. The outer peripheral wall portion341includes ribs341A and a discharge port sealing part341B. The ribs341A are disposed on the outer peripheral wall portion341and extend in the first direction. The ribs341A are spaced from one another in a circumferential direction of the outer peripheral wall portion341. The ribs341A are in slight contact with the inner circumferential portion31K, and function to prevent the movable wall34from tilting in the first direction in the container body31. The discharge port sealing part341B is defined by a lowest part of the outer peripheral wall portion341and has a sufficient size to cover the toner discharge port319.

The inner wall seal342is disposed on the outer peripheral wall portion341on a rear end joining the conveying wall portion340in such a way as to ride on a circumference of the rear end of the outer peripheral wall portion341. As shown inFIG. 10A, the inner wall seal342is first secured to the top of the conveying wall portion340at a first seal end342A thereof, and is then wound around the conveying wall portion340and finally secured at a second seal end342B thereof in such a manner that the first seal end342A and the second seal end342B overlap each other. The inner wall seal342is resiliently compressed between the inner circumferential portion31K of the container body31and the movable wall34. The inner wall seal342defines the outer circumferential portion34K of the movable wall34. The outer circumferential portion34K is slidably disposed in close contact with the inner circumferential portion31K of the container body31. The inner wall seal342prevents toner in the storage space31S from flowing out to the upstream side of the movable wall34in the moving direction through the gap between the inner circumferential portion31K of the container body31and the movable wall34.

The shaft seal343is disposed on the bearing340A at the downstream side of the female thread340D in the moving direction of the movable wall34(FIG. 11). The shaft seal343comes in contact with the male thread333of the shaft33in the movement of the movable wall34. At this time, the shaft seal343comes in contact with the male thread333before the female thread340D to clean toner adhered on the male thread333. This allows the male thread333to engage with the female thread340D after toner adhered thereon is removed almost completely. Therefore, it is possible to prevent aggregation of toner between the male thread333and the female thread340D and consequently allow a stabilized movement of the movable wall34. Further, the shaft seal343is in the form of a ring, and therefore is in close contact with the shaft33over the entire circumference of the shaft33for sealing the bearing340A. This prevents toner in the storage space31S from flowing out to the upstream side of the movable wall34in the moving direction through the bearing340A. The movable wall shaft hole34J allowing the shaft33to pass therethrough is defined radially inside the shaft seal343being in the form of a ring and the cylinder part340C.

The supply opening caps344are fitted in the toner supply openings340B through the inside of the outer peripheral wall portion341to seal the toner supply openings340B, as shown inFIG. 10B. After replenishment toner is filled in the container space31S through the toner supply openings340B, the supply opening caps344are respectively fitted into the toner supply openings340B. Consequently, the toner is prevented from leaking through the toner supply openings340B.

The washer35(FIG. 9) is disposed between the cylinder part340C of the movable wall34and the sponge seal36and placed around the shaft33.

The sponge seal36is disposed between the washer35and the lid37. The sponge seal36prevents leakage of toner through the lid shaft hole37J of the lid37described later, the lid37being secured to the container body31.

The lid37(FIGS. 9 and 11) is secured to the flange316of the container body31and seals the opening of the container body31. The lid37includes the lid shaft hole37J. The shaft33is rotatably and axially supported in the lid shaft hole37J at the first shaft end portion331.

The rotary gear38is secured to the first shaft end portion331of the shaft33. A distal end of the first shaft end portion331has a D-shape in sectional view perpendicularly intersecting its axial direction. The rotary gear38is formed with an unillustrated D hole in a central part thereof, the D hole engaging with the distal end of the first shaft end portion331having the D-shape. The rotary gear38rotates integrally with the shaft33. The rotary gear38includes an outer peripheral gear portion381. The outer peripheral gear portion381is defined by an outer peripheral portion of the rotary gear38. The gear teeth of the outer peripheral gear portion381are not shown in the drawings. The rotary gear38is connected to the motor M (FIG. 8B) (driving source) disposed in the housing101of the printer100. Upon receipt of a torque from the motor M, the rotary gear38transmits the torque to the shaft33to move the movable wall34in the first direction.

The cover39is disposed at an end of the toner container30. With reference toFIG. 8C, the cover39has such a shape to cover a half of the circular side face of the rotary gear38. In other words, when the cover39is secured to the container body31via the lid37, a half of the circular side face of the rotary gear38is exposed to the outside of the toner container30. The cover39includes a shaft cover portion391and the second guiding portion392. The shaft cover portion391is formed in a central part of the cover39and is in the form of a cylinder. The shaft cover portion391covers the end of the first shaft end portion331projecting from the rotary gear38. The second guiding portion392is disposed behind the shaft cover portion391and is in the form of a protrusion vertically extending. The second guiding portion392functions to guide mounting of the toner container30into the printer100.

Each of the screws40is fastened to the flange316of the container body31after being inserted into unillustrated screw holes respectively formed in the lid37and the cover39. Consequently, the container body31, the lid37, the rotary gear38, and the cover39constitute an integral structure, with the stirring disc32, the shaft33, and the movable wall34being disposed in the internal space31H.

Further, the toner container30includes a toner sensor31T (FIGS. 8A and 8B). The toner sensor31T is disposed on the top portion312of the container body31above the toner discharge port319. The toner sensor31T includes a magnetic permeability sensor or a piezoelectric element. In the case where the toner sensor31T includes a piezoelectric element, a sensing portion of the toner sensor31T is exposed to the storage space31S. The toner sensor31T outputs a HIGH signal (+5V) in response to being pressed by toner in the storage space31S. Further, when no toner exists directly under the toner sensor31T, the toner sensor31T outputs a LOW signal (0V). A signal outputted by the toner sensor31T is referred to by a controller50described later. In the case where the toner sensor31T is configured as a magnetic permeability sensor, the sensor does not need to make direct contact with toner. Therefore, in other embodiments, the toner sensor31T may be disposed on the housing101of the printer100and opposite an outer wall of the container body31. Further, the toner sensor31T is not limited to be disposed on the top portion312. In other embodiments, the toner sensor may be disposed on any one of the bottom portion311, the front wall313, and the rear wall314of the container body31. In the case where the toner sensor is disposed on a lowest part of the bottom portion311, the toner discharge port319may be formed at a position circumferentially away from the lowest part.

As described above, the toner container30can be attached to and detached from the developing device20. With reference toFIG. 2, when the opening/closing cover100C of the housing101is opened upward, a container housing space109is exposed to the outside of the housing101, the container housing space109constituting a part of the main body internal space107. In the present embodiment, the toner container30is mounted in the container housing space109from above (see an arrow DC shown inFIGS. 6 and 7). At this time, the cover39of the toner container30comes to rest at the right end of the container housing space109, and the left wall315of the toner container30comes to rest at the left end of the container housing space109. The printer100includes guide grooves109A (FIG. 2). The guide grooves109A are formed in the container housing space109and vertically extend. AlthoughFIG. 2shows only a right guide groove109A, there is also a left guide groove109A similarly disposed at the left end of the container housing space109.

The toner container30is mounted in the container housing space109by a user, with the first guiding portion318and the second guiding portion392engaging with the pair of guide grooves109A. After the toner container30is mounted in the container housing space109, a user or an unillustrated opening/closing mechanism slides the shutter317to open the toner discharge port319. Consequently, the toner discharge port319lies above and opposite the toner supply port25(FIGS. 4 and 5).

FIGS. 12A, 12B, and 12Care sectional views each illustrating a movement state of the movable wall34in the toner container30.FIG. 12Ashows the movable wall34located at an initial position.FIG. 12Bshows the movable wall34having moved from the initial position in the first direction.FIG. 12Cshows the movable wall34located at a final position.

As shown inFIG. 12A, when the toner container30is newly mounted in the printer100by a user, the movable wall34lies at the initial position adjacent to the lid37and remote from the toner discharge port319at one end side of the internal space31H in the first direction. Even if the storage space31S is maximally filled with toner when the toner container30is manufactured, a slight space is left in the storage space31S. This space is necessary to impart a predetermined fluidity to the toner contained in the storage space31S before use of the toner container30. However, in this case, because a boundary surface (top surface) of the toner contained in the storage space31S is located under the top portion312with a specific gap therebetween, the toner sensor31T can be seen to be difficult to detect the toner contained in the storage space31S with high accuracy.

Accordingly, when the toner container30is newly mounted in the printer100, the controller50(FIG. 8B) causes the motor M to drive the rotary gear38and the shaft33for rotation. This brings the male thread333into engagement with the female thread340D to thereby impart a moving force to the movable wall34in the first direction toward the toner discharge port319. When the movable wall34has moved slightly leftward from the initial position shown inFIG. 12A, the storage space31S is filled up with toner. This allows the toner sensor31T to detect the toner in the storage space315. Upon receipt of the HIGH signal outputted from the toner sensor31T, the controller50causes the movement of the movable wall34to stop.

In the present embodiment, the inner circumferential portion31K of the container body31and the outer circumferential portion34K (outer peripheral wall portion341) of the movable wall34each have, in sectional view perpendicularly intersecting the first direction, a non-circular shape. This makes it possible to prevent the movable wall34from rotating with respect to the container body31even when the movable wall34receives a force for rotation around the shaft33, owing to the engagement of the male thread333and the female thread340D. Consequently, the movable wall34can be moved steadily in the first direction by a torque of the motor M. Further, the engagement of the male thread333and the female thread340D allows the movable wall34to move steadily in the first direction with the outer circumferential portion34K of the movable wall34being in close contact with the inner circumferential portion31K of the container body31as described above.

As described above, the present embodiment employs the volume replenishment type toner supply method as shown inFIG. 5. Therefore, when the toner supply port25is sealed by the accumulation portion29(FIG. 5) existing in the developing device20from below, no replenishment toner falls from the toner container30. On the other hand, when the toner of the accumulation portion29decreases as a result of supply of toner from the developing roller21of the developing device20to the photoconductive drum121, toner flows into the developing device20through the toner supply port25from the toner discharge port319. Consequently, toner that has existed under the toner sensor31T disappears in the storage space31S of the toner container30, which causes the toner sensor31T to output the LOW signal. Upon receipt of the signal, the controller50drives the motor M to move the movable wall34toward the toner discharge port319(FIG. 12B) until the toner sensor31T outputs the HIGH signal. At this time, the stirring disc32disposed at the extreme end of the storage space31S rotates with the shaft33to stir toner existing above the toner discharge port319. This increases the fluidity of the toner, so that toner falls through the toner discharge port319constantly.

The movable wall34reaches the final position near the toner discharge port319as a result of progressive consumption of toner from the storage space31S of the toner container30, as shown inFIG. 12C. In this manner, the movable wall34gradually moves in the first direction to thereby convey toner in the storage space31S to the toner discharge port319by pushing it. At this time, the storage space31S gradually decreases as the movable wall34approaches the toner discharge port319. Therefore, the space accommodating remaining toner gradually disappears in the toner container30. Finally, at the final position shown inFIG. 12C, the movable wall34comes into contact with the stirring disc32, so that the storage space31S almost disappears. This makes it possible to reduce the amount of toner remaining in the storage space31S of the container body31at the end of use of the toner container30, as compared to the conventional toner container whose storage space volume does not change.

When the movable wall34reaches the final position facing the toner discharge port319, the discharge port sealing part341B (FIG. 10B) of the movable wall34covers the toner discharge port319from the inside of the container body31(FIG. 12C). In other words, the movable wall34has a shutter function of covering the toner discharge port319when the toner in the container body31runs out. This makes it possible to, even when the toner container30is dismounted from the printer100with the shutter317left open, prevent a small amount of toner remaining in the gap between the stirring disc32and the movable wall34from leaking or scattering out of the toner discharge port319. In particular, in the present embodiment, the inner wall seal342being in close contact with the inner circumferential portion31K of the container body31lies at the downstream end of the movable wall34in the moving direction during the movement of the movable wall34. Consequently, the discharge port sealing part341B covering the toner discharge port319is hardly adhered with toner, the discharge port sealing part341B lying at the upstream side of the inner wall seal342in the moving direction of the movable wall34. In addition, the width of the outer peripheral wall portion341is set to be longer than the width of the toner discharge port319in the first direction, so that the discharge port sealing part341B has a size sufficient to cover the toner discharge port319. Therefore, it is possible to reliably cover the toner discharge port319by the discharge port sealing part341B.

Further, when the movable wall34seals the toner discharge port319at the final position as described above, a user can recognize that the toner has run out by seeing the sealing state. When the amount of toner remaining in the toner container30decreases, it is difficult to tell the amount of remaining toner by the weight of the toner container30. On the other hand, in the case where the shutter317is slid as described above, a user can reliably recognize, by seeing that the toner discharge port319is sealed by the movable wall34, that the toner in the toner container30has run out. Consequently, the user can be prompted to replace the toner container30.

Further, the above-described function of the movable wall34of sealing the toner discharge port319can be utilized also in the case where a toner container30that has been partially used is dismounted from the printer100for some reason and stored with other empty toner containers30. Specifically, a user is only required to choose a toner container30in which the toner discharge port319is not sealed by the movable wall34, from among the plurality of stored toner containers30.

In addition, in the case where the volume replenishment type toner supply method is employed as described above, when the toner in the toner container30runs out, no replenishment toner presses the accumulation portion29, so that no pressing force is exerted to the developing device20from the toner container30. In this case, there is a possibility that a part of the toner in the developing device20flows back toward the toner discharge port319through the toner supply port25because of various conditions in the developing device20. However, in the present embodiment, the movable wall34seals the toner discharge port319. This can prevent the toner from flowing back into the container body31from the developing device20(supply receiver).

In addition, in the present embodiment, the toner supply openings340B for filling toner into the storage space S are formed in the movable wall34when the toner container30is manufactured, as described above. Therefore, there is no need to form a filling port in the container body31in addition to the toner discharge port319. Therefore, the container body31can be formed in a simple shape. There may be provided toner containers30filled with different amounts of toner by varying the initial position of the movable wall34in the first direction. It is possible to change the volume of the storage space31S by changing the initial position of the movable wall34at the time of filling toner. Also in this case, the toner supply openings340B are formed in the movable wall34of each of the toner containers31and, therefore, it is not necessary to form a filling port in the container body31of each of the toner containers30at different positions from one another according to the amount of toner to be filled. This allows use of the container bodies31of the same type. Further, even in the case where toner containers30are filled with different amounts of toner, the initial position of the movable wall34of each of the toner containers30may be commonly set at a position shown inFIG. 12A. In this case, when a toner container30is mounted in the printer100, a driving time for allowing the motor M to run is adjusted according to the output signal of the toner sensor31T as an initial setting. Consequently, the storage space31S is filled up with toner.

Further, the toner container30includes a backward movement preventing mechanism55(FIG. 11). The backward movement preventing mechanism55prevents the movable wall34having reached the toner discharge port319from moving back toward the initial position. In the present embodiment, the movable wall stopper portion334of the shaft33functions as the backward movement preventing mechanism55as shown inFIGS. 11 and 12A. The movable wall stopper portion334is defined by a specific part of the shaft33, the specific part not bearing the male thread333and facing the toner discharge port319, as described above. Therefore, the female thread340D (FIG. 10B) of the movable wall34disengages from the male thread333and comes to lie in front of the movable wall stopper portion334, immediately before the movable wall34reaches the final position shown inFIG. 12C. Thus, once the movable wall34reaches the final position shown inFIG. 12C, the female thread340D is prevented from engaging with the male thread333again. Consequently, the movable wall34will never move back toward the lid37even if the rotary gear38is rotated accidentally inversely. Therefore, as described above, it is possible to reliably locate the movable wall34at the final position when the toner container30is empty of the toner. This can prevent leakage or scattering of toner out of the toner discharge port319. Further, even in the case where a used toner container30is stored in a vertical position such that the first direction agrees with a vertical direction, the movable wall34is prevented from moving back toward the lid37by its own weight.

Further, at the final position shown inFIG. 12C, the inner wall seal342of the movable wall34resiliently radially biases the inner circumferential portion31K of the toner container30from the inside. This allows the movable wall34to be stably locked at the final position and thereby further prevented from moving backward.

Now, a toner container30Q according to a second embodiment of the present invention will be described with reference toFIGS. 13A, 13B and 14.FIGS. 13A and 13Bare perspective views of a movable wall34Q of the toner container30Q.FIG. 14is a sectional perspective view of the toner container30Q with a shutter317Q closed. In these drawings, elements that have functions identical to those of the corresponding elements of the toner container30in the first embodiment are denoted by the same reference numerals as in the first embodiment, with “Q” added at the end. The second embodiment differs from the toner container30of the first embodiment in the structures of the shutter317Q and the movable wall34Q. Accordingly, description will be made mainly regarding the difference, and repeated description of other common features will be omitted.

The toner container30Q includes a container body31Q, the shutter317Q, and the movable wall34Q. With reference toFIG. 14, the shutter317Q is in the form of a cylinder and fitted on the outer surface of the container body31Q. The shutter317Q functions to close and open a toner discharge port319Q) of the container body31Q. The shutter317Q includes a shutter holder317Q1. The shutter holder317Q1projects upward from the shutter317Q. The shutter holder317Q1is held by a user after the toner container30Q is mounted in the container storage109(FIG. 2) of the printer100. The user slides the shutter holder317Q1in a left-right direction to thereby move the shutter317Q to a position at which the toner discharge port319Q is covered by the bottom end of the shutter317Q or to a position at which the toner discharge port319Q is open.

With reference toFIGS. 13A and 13B, the movable wall34Q has substantially the same structure and shape as those of the movable wall34of the first embodiment. However, as shown inFIG. 13A, an inner wall seal342Q of the movable wall34Q is formed to be wide in the left-right direction (first direction). The lateral width of the inner wall seal342Q is set to be longer than the lateral opening width of the toner discharge port319Q shown inFIG. 14.

Also in the second embodiment, when the movable wall34Q reaches a final position, the inner wall seal342Q covers the entirety of the toner discharge port319Q from the inside of the container body31Q, as shown inFIG. 14. Therefore, it is possible to reliably seal the toner discharge port319Q by the movable wall34Q. Further, the inner wall seal342Q is made of a resilient material such as urethane. Therefore, the inner wall seal342Q is partially released from a resiliently compressed state at the toner discharge port319Q. Consequently, a part of the surface of the inner wall seal342Q protrudes out of the toner discharge port319Q radially outward of a shaft33Q. This allows a part of the inner wall seal342Q to be closely adhered to the peripheral edge of the toner discharge port319Q and thereby improve its ability of sealing the toner discharge port319Q.

Further, also in the second embodiment, the movable wall34Q is prevented from moving back from the final position toward an initial position, owing to a movable wall stopper portion334Q defined by a specific part of the shaft33, the specific part not bearing a male thread333Q and facing the toner discharge port319Q. At this time, the protruding surface portion of the inner wall seal342Q is caught on an opening end319Q1(FIG. 14) of the toner discharge port319. Therefore, the movable wall34Q is further prevented from moving back toward the initial position. In other embodiments, the inner wall seal342Q may have such a shape as to allow a seal end342Q1(FIG. 13B) of the inner wall seal342Q to be located at the left side (i.e. the downstream side in the moving direction of the movable wall34Q) of the opening end319Q1when the movable wall34Q is at the final position shown inFIG. 14. In this case, the seal end342Q1slightly protruding out of the toner discharge port319is likely to be easily caught on the opening end319Q1, which will further prevent the movable wall34Q from moving back toward the initial position.

When the shutter317Q is slid by a user after the movable wall34Q reaches the final position shown inFIG. 14, the toner discharge port31Q is doubly sealed by the movable wall34Q and the shutter317Q. In particular, in the second embodiment, the toner discharge port319Q is sealed from the inside and the outside of the container body31Q. This makes it possible to stably prevent the vicinity of the container body31Q from getting stained with toner.

Now, a toner container30P according to a third embodiment of the present invention will be described with reference toFIG. 15.FIG. 15is a sectional view illustrating a state that a movable wall34P of the toner container30P is at a final position. InFIG. 15, elements that have functions identical to those of the corresponding elements of the toner container30in the first embodiment are denoted by the same reference numerals as in the first embodiment, with “P” added at the end. The third embodiment differs from the toner containers30and30Q of the first and the second embodiments in the aspect of including a one-way clutch385. Accordingly, description will be made mainly regarding the difference, and repeated description of other common features will be omitted.

In the third embodiment, the one-way clutch385, in addition to a movable wall stopper portion334P disposed at a leading end of a shaft33P, functions as the backward movement preventing mechanism55. The one-way clutch385is secured to an inner circumferential portion of a rotary gear38P and fitted on an outer circumferential portion of a first shaft end portion331P.

While the rotary gear38P coaxially connected to the shaft33P is rotated in a first rotational direction (in the direction of an arrow R1shown inFIG. 15) by the motor M (FIG. 8B), a male thread333P of the shaft33P rotates. This allows a bearing340AP having a female thread340DP to move integrally with the movable wall34P in a first direction (in the direction of an arrow DA shown inFIG. 15). At this time, the one-way clutch385connecting the shaft33P and the rotary gear38P transmits a torque of the first rotational direction transmitted from the motor M to the rotary gear38to the first shaft end portion331P.

After the movable wall34P reaches a toner discharge port319P, the toner container30P is dismounted from the printer100by a user. At this time, even if the user accidentally touches the rotary gear38P and rotates the rotary gear38P in a second rotational direction (in the direction of an arrow R2shown inFIG. 15) opposite to the first rotational direction, the shaft33P is prevented from rotating in the second rotational direction, owing to the one-way clutch385. Therefore, the movable wall34P is prevented from moving back toward an initial position closer to a lid37P. Consequently, it is possible to prevent scattering of toner out of the toner discharge port319P. Further, in the third embodiment, the movable wall34P is prevented from moving back toward the initial position also during the movement in the first direction. This prevents accidental expansion of the storage space in a container body31P.

Now, a toner container30R according to a fourth embodiment of the present invention will be described with reference toFIGS. 16 to 18.FIG. 16is a sectional view illustrating a state that a movable wall34R of the toner container30R is at an initial position.FIGS. 17 and 18are sectional views illustrating a state that the movable wall34R of the toner container30R is at a final position. InFIGS. 16 to 18, elements that have functions identical to those of the corresponding elements of the toner container30in the first embodiment are denoted by the same reference numerals as in the first embodiment, with “R” added at the end. The fourth embodiment differs from the toner containers30and30Q of the first and the second embodiments in that a shaft33R slides. Accordingly, description will be made mainly regarding the difference, and repeated description of other common features will be omitted. In the fourth embodiment, a motor M (FIG. 16) disposed in the printer100is rotatable in forward and backward directions

Similarly to the above-described embodiments, the toner container30R includes a container body31R, a stirring disc32R, the shaft33R (shaft), the movable wall34R, a lid37R, a rotary gear38R (drive transmitter), and a cover39R. The rotary gear38R includes a gear shaft hole38JR (shaft hole) and is coaxially disposed with respect to the shaft33R.

A first shaft end portion331R of the shaft33has a D-shape in sectional view. On the other hand, the gear shaft hole38JR of the rotary gear38R is in the shape of D. The first shaft end portion331R passes through the gear shaft hole38JR. The shaft33R is integrally rotatable with the rotary gear38R when the rotary gear38R is rotated in a first rotational direction (in the direction of an arrow R1shown inFIG. 16) by a controller50R. In the fourth embodiment, the first shaft end portion331R is slidable in a first direction with respect to the gear shaft hole38JR.

Further, as shown inFIG. 16, a left wall315R of the container body31R includes a cavity315R1. The cavity315R1is formed in the left wall315R and axially faces a second shaft end portion332R of the shaft33R when the movable wall34R is at the initial position. Similarly to the first shaft end portion331R, the second shaft end portion332R also has a D-shape in sectional view. The second shaft end portion332R passes through a D hole formed in the stirring disc32R to allow the stirring disc32R to integrally rotate with the second shaft end portion332R.

During the movement of the movable wall34R to a toner discharge port319R from the initial position shown inFIG. 16, the shaft33R is imparted with a moving force in the right direction, owing to engagement of a male thread333R with a female thread340DR. However, because a distal end of the first shaft end portion331R is in contact with a shaft cover portion391R of the cover39R, the shaft33R is prevented from sliding rightward.

Upon arrival of the movable wall34R at the toner discharge port319R (FIG. 17), the controller5OR controls the motor M to cause the rotary gear38R to rotate in a second rotational direction (in the direction of an arrow R2shown inFIG. 17) opposite to the first rotational direction. At this time, the shaft33R is imparted with a moving force in the left direction (in the first direction or the direction of an arrow DA shown inFIG. 17), owing to the engagement of the male thread333R with the female thread340DR. Consequently, the shaft33R slides leftward and the first shaft end portion331R disengages from the gear shaft hole38JR of the rotary gear38R (FIG. 18). At the same time, the second shaft end portion332R of the shaft33R enters the cavity315R1. Thus, the shaft33R is prevented from receiving a torque from the rotary gear38R. Therefore, the movable wall34R having reached the final position is reliably prevented from moving back. In addition, also in the fourth embodiment, an inner wall seal342R of the movable wall34R pushes an inner circumferential portion31KR of the container body31R from the inside when the movable wall34R is at the final position. Therefore, the movable wall34R is prevented from moving back toward the initial position during the rotation of the rotary gear38R in the second rotational direction. As described above, in the fourth embodiment, the shaft33R and the cavity315R1function as the backward movement preventing mechanism55.

The toner container30(30P,30Q,30R) and the printer100including the same according to the embodiments of the present invention have been described. According to the above-described configurations, it is possible to form an image on a sheet while efficiently using the toner in the toner container. Further, it is possible to reliably maintain the covered state of the toner discharge port after the end of use of the toner container. The present invention is not limited to the above-described embodiments and, for example, the following modified embodiments may be adopted.

(1) In the above-described embodiment, the printer100is illustrated as a monochrome printer. However, the present invention is not limited to this configuration. In particular, in the case where the printer100is provided as a tandem color printer, after the opening/closing cover100C (FIG. 2) of the printer100is opened, toner containers30respectively corresponding to a plurality of colors may be mounted in the housing101from above so as to be adjacent to one another.

(2) In the first embodiment, the toner container30is mounted in the printer100in the longitudinal direction of the developing device20. However, the present invention is not limited to this configuration. It may be configured such that the toner container30is mounted in a direction intersecting the longitudinal direction of the developing device20.

(3) In the second embodiment, the toner container30Q includes the shutter317Q. However, the present invention is not limited to this configuration. As described above, the movable wall34Q seals the toner discharge port319Q when it reaches the final position. Accordingly, a film seal may be disposed at the toner discharge port319Q, the film seal for sealing the toner discharge port319Q until the toner container30Q begins to be used. When the toner container30Q is newly mounted in the printer100, the film seal is peeled off by a user. Consequently, the toner discharge port319Q is opened to communicate with an unillustrated developing device. Eventually, when toner in the toner container30Q runs out, the inner wall seal342Q of the movable wall34Q covers the toner discharge port319Q, as described above.

(4) The first embodiment employs the volume replenishment type toner supply method. However, the present invention is not limited to this method. An unillustrated toner sensor may be disposed at the developing device20so that when the toner sensor detects a decrease of toner in the developing device20, the controller50drives the motor M to move the movable wall34in the first direction. This allows toner to fall through the toner discharge port319to flow into the developing device20.

(5) In the first embodiment, the bearing340A is disposed in the central part of the movable wall34. However, the present invention is not limited to this configuration. The bearing340A may be disposed in another area of the movable wall34. It may be configured such that the bearing340A is disposed in an upper part of the movable wall34, and the shaft33correspondingly extends in an upper part of the container body31. In this case, pressure of toner that is exerted on the shaft seal343(FIG. 10A) will be low, so that the shaft seal343can maintain a higher level of sealing ability.