Developing device and image forming apparatus

A developing device is provided that includes a developer containing case that contains a developer. The developer containing case includes a case main body and a supply roller that is rotatably supported on the case main body. The supply roller has a rotary shaft, a cylindrical roller main body that covers the rotary shaft, and a fixed member that is fixed to at least one of the rotary shaft and the roller main body. A gap is provided between an end surface of the roller main body and an inner surface of the case main body, and the fixed member partially occupies the gap.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Applications No. 2005-287545, filed on Sep. 30, 2005, and No. 2006-016495, filed on Jan. 25, 2006, the entire subject matters of which are incorporated herein by reference.

TECHNICAL FIELD

Aspects of the present invention relate to a developing device having a developer containing case that contains a developer, such as a toner or the like.

Further aspects of the present invention relate to a developing device used in a laser printer or the like, a process cartridge having such a developing device, and an image forming apparatus, such as a laser printer or the like, on which such a process cartridge is mounted.

BACKGROUND

For example, a laser printer performs printing on a recording medium (for example, a printing sheet) using a developer (for example, a toner). The laser printer has a case that contains the developer. The developer containing case has a case main body and a pair of rollers that are rotatably supported on the case main body. One roller is called a supply roller, and the other roller is called a developing roller. The supply roller carries the developer that is contained in the case main body. The supply roller has a rotary shaft and a cylindrical roller main body that covers the rotary shaft. The developing roller comes into contact with the supply roller outside the case main body than the supply roller does. The developing roller and the supply roller rotate while coming into contact with each other, and then the developer is supplied from the supply roller to the developing roller. At this time, the developer is positively or negatively charged by friction between the developing roller and the supply roller. The developing roller carries the positively or negatively charged developer.

The laser printer has a photosensitive member that comes into contact with the developing roller. An electrostatic latent image is formed on the surface of the photosensitive member. The developing roller and the photosensitive member rotate while coming into contact with each other, and then the developer carried on the developing roller is attached to parts of the electrostatic latent image of the photosensitive member. Accordingly, the electrostatic latent image of the photosensitive member becomes a visual image. The developer having the visual image is transferred from the photosensitive member to the recording medium, such that a letter or a drawing is printed on the recording medium.

JP-A-2002-287487 discloses a laser printer having the above-described configuration.

A developing device has a seal member that prevents developer leakage from both longitudinal ends of the developer carrier. For example, JP-A-11-190941 discloses a technique related to a developing device, a process cartridge, and an image forming apparatus that repeats a removal operation of a toner on and in an elastic roller by a scrape roller, a scrape operation of a toner stuck to a wall of a developing container by the elastic roller, and a scrape operation of the toner by the scrape member. According to this technique, an end seal member is provided at an opening of the developing container so as to seal between both ends of a developing sleeve and the developing container. The end seal member comes into contact with peripheral surfaces of both ends of the developing sleeve. Further, a side surface of the end seal member comes into contact with side surfaces of both longitudinal ends of an elastic blade, such that toner leakage from sides of the elastic blade is prevented. In addition, the scrape member is provided at a portion where the elastic blade does not come into contact with the developing sleeve and on the peripheral surfaces of both ends of the elastic roller, that is, portions where the elastic roller comes into contact with the developing sleeve.

With this configuration, the scrape member does not supply the toner from the elastic roller onto the peripheral surfaces of both ends of the developing sleeve, but scrapes the toner. Accordingly, the toner stuck onto the peripheral surfaces in the vicinity of the end seal member of the developing sleeve is made small. Therefore, it is possible to provide a developing device, a process cartridge, and an image forming apparatus that can prevent the toner from entering between the seal member and the developing sleeve.

SUMMARY

A particle diameter of the developer is very small. For this reason, even though the case main body is sealed airtight, the developer may leak outside the case main body. If the developer leaks, various devices disposed at the outside are stained. It is necessary to construct the developer containing case such that the developer can be prevented from leaking.

The inventors have found that the developer carried by the roller main body of the supply roller moves in a rotary shaft direction. That is, it has been found that the developer moves from the roller main body toward an inner surface of the case main body. In this case, the developer that moves toward the inner surface of the case main body may enter a narrow space existing near the inner surface of the case main body (for example, a space between the developing roller and a member sealing the developing roller). When this space is connected to the outside of the case main body, the developer that enters the space may leak to the outside of the case main body.

One aspect of the invention provides a technique that can suppress a developer from leaking from an inner surface of a case main body.

In JP-A-11-190941, if the scrape member is provided, when the scraped toner is stuck to the scrape member itself, an aggregate of the toner is formed. Then, the aggregate may enter the end seal member and cause toner leakage. Accordingly, instead of using the scrape member, if both longitudinal ends of the elastic blade that come into contact with the developing sleeve at a curved surface are processed in cutout shapes, and both longitudinal ends of the elastic blade comes into linear contact with the developing sleeve, the toner is not placed onto the peripheral surfaces in the vicinity of the end seal member of the developing sleeve, and thus toner leakage can be prevented. In this case, however, toner fluidity at both longitudinal ends of the developing sleeve is not undesirable. Further, when the developing device is used for many hours, the scraped toner is stuck little at a time onto a rear side as viewed from the openings of the cutouts of both longitudinal ends of the elastic blade, and thus an aggregate of the toner is formed. Then, the aggregate enters the end seal member, which causes toner leakage.

Accordingly, another aspect of the invention provides a developing device that prevents an aggregate of a developer from occurring and prevents developer leakage from a seal member, a process cartridge, and an image forming apparatus.

The inventors have created a technique that provides a gap between an end surface of the roller main body and the inner surface of the case main body. According to this technique, a developer that moves from a roller main body in a rotary shaft direction enters the gap. Then, the developer rarely reaches the inner surface of the case main body. With this configuration, the developer can be suppressed from leaking from the inner surface of the case main body.

However, the developer that enters the gap remains in the gap. If the developer remains near the inner surface of the case main body, the developer whose place to go is lost may leak from the inner surface of the case main body to the outside of the case main body. If the gap is provided between the end surface of the roller main body and the inner surface of the case main body, the gap can suppress the developer from leaking until the gap is filled with the developer, but developer leakage may occur after the gap is filled with the developer. One aspect of the invention can effectively suppress developer leakage by allowing the developer so as not to remain in the gap between the end surface of the roller main body and the inner surface of the case main body.

DETAILED DESCRIPTION

The technique according to one aspect of the invention will be described with reference toFIGS. 1 and 2.FIGS. 1 and 2are diagrams illustrating the technical concept of the one aspect. A shape or a position of each member is not limited to that shown in the drawing.

FIG. 1is a perspective view showing a portion of a developer containing case500. The developer containing case500has a case main body502and a first roller504that is rotatably supported on the case main body502. The first roller504has a rotary shaft506, a cylindrical roller main body508that covers the rotary shaft506, and a fixed member510that is fixed to the rotary shaft506and/or the roller main body508. InFIG. 1, the fixed member510is fixed to the rotary shaft506. A gap512is provided between an end surface508aof the roller main body508and an inner surface502aof the case main body502. The fixed member510partially occupies the gap512.

In the developer containing case500, the gap512is provided. The developer that moves from the roller main body508in a direction of the rotary shaft508enters the gap512. For this reason, the developer rarely reaches the inner surface502aof the case main body502. In this technique, when the first roller504rotates, the fixed member510also rotates. Accordingly, the fixed member510can scrape off the developer that enters the gap512. The developer rarely remains near the inner surface502aof the case main body502. With the developer containing case500, developer leakage can be effectively suppressed.

The first roller504may be a so-called supply roller or may be a so-called developing roller. Further, other kinds of roller may be used.

The fixed member510is not limited to one fixed to the rotary shaft506. Another example will be described with reference toFIG. 2.FIG. 2is a front view of a portion of the developer containing case500. InFIG. 2, a fixed member510ais fixed to the roller main body508. Further, a fixed member510bis fixed to the rotary shaft506and the roller main body508. With the fixed member510aor510b, the developer that enters the gap512can also be scraped off.

The fixed member may be formed separately from the roller main body. The fixed member may be formed integrally with the roller main body.

In the latter case, the roller main body and the fixed member can be formed by cutting a material. With this configuration, since the roller main body and the fixed member can be manufactured from one material, the number of kinds of material required for manufacturing the developer containing case can be reduced.

If the fixed member mostly occupies the gap, the gap is no more meaningful. For this reason, the fixed member preferably has a volume half or less of a volume of the gap.

With this configuration, a gap having a sufficient size can be provided between the end surface of the roller main body and the inner surface of the case main body.

The volume of the gap can be obtained by subtracting, from a volume of a region indicated by a two-dot-chain line ofFIG. 2, a volume of the rotary shaft506in that region.

The fixed member may have various shapes. Examples of the shape of the fixed member are as follows.

(1) In front view of the end surface of the roller main body, the fixed member may have a rectangular shape that extends from a vicinity of a center of the end surface of the roller main body radially outward.

(2) In front view of the end surface of the roller main body, the fixed member may extend from a vicinity of a center of the end surface of the roller main body radially outward and bend in a reverse rotation direction of the first roller.

(3) In front view of the end surface of the roller main body, the fixed member may have a sectoral shape that is widened from a vicinity of a center of the end surface of the roller main body radially outward.

(4) In front view of the end surface of the roller main body, the fixed member may have a vane shape that extends from a vicinity of a center of the end surface of the roller main body radially outward.

(5) In front view of the end surface of the roller main body, the fixed member may extend beyond the end surface of the roller main body outward. The fixed member510bofFIG. 2corresponds to this configuration.

(6) The fixed member may extend from the end surface of the roller main body to the inner surface of the case main body.

With any configuration of (1) to (6), the developer that enters the gap can be effectively scraped off.

The developer containing case may further include a second roller that is rotatably supported on the case main body, and a side seal member that is fixed to the case main body. The second roller comes into contact with the first roller outside the case main body than the first roller does. The case main body has a region that opposes a rotary surface of the second roller at an end in a rotary shaft direction of the second roller. The side seal member is disposed in the opposing region and comes into contact with the second roller. The end surface of the roller main body of the first roller may oppose the case main body and the side seal member.

With this configuration, an end of the second roller can be sealed by the side seal member.

The end surface of the roller main body opposes the case main body and the side seal member. If the fixed member is not provided, the developer may remain in the gap between the end surface of the roller main body and the inner surface of the case main body, and the developer may enter a narrow space between the side seal member and the rotary surface (peripheral surface) of the second roller. For this reason, developer leakage may occur. Since the fixed member is provided, the developer rarely remains in the gap between the side seal member and the second roller. As a result, the developer can be effectively suppressed from entering the gap between the side seal member and the second roller.

The side seal member may have a first layer that is fixed to the case main body, and a second layer that is laminated on the first layer and comes into contact with the second roller. The first layer may be formed of an elastic material, and the second layer may be formed of a fiber material.

The first layer is formed of an elastic material, and thus the side seal member can be tightly pressed against the second roller. Further, a general fiber material has a small coefficient of friction. For this reason, the second roller can smoothly rotate while coming into contact with the second layer.

The fixed member may be formed of the same fiber material as the second layer of the side seal member.

With this configuration, the number of kinds of material required for forming the developer containing case can be reduced. Further, since the developer is caught by fiber of the fixed member, the fixed member can effectively scrape off the developer.

The developer containing case may further include a layer-thickness regulating member that is fixed to the main body case. The layer-thickness regulating member comes into contact with the second roller, and regulates a thickness of the developer carried on the second roller. A cutout may be provided at a predetermined position of the layer-thickness regulating member. With this configuration, a contact area of the layer-thickness regulating member with the second roller is larger in a portion other than the cutout, and is smaller at the cutout. If the contact area is large, a low pressure is applied from the layer-thickness regulating member to the second roller. If the contact area is small, a high pressure is applied from the layer-thickness regulating member to the second roller. Then, a developer layer of the second roller is thicker at a portion where the contact area is large, and is thinner at a portion where the contact area is small.

The cutout is provided at a position corresponding to the end in the rotary shaft direction of the second roller. For this reason, at the end in the rotary shaft direction of the second roller, the developer layer is thinned. The end in the rotary shaft direction of the second roller is near the inner surface of the case main body. With this configuration, near the inner surface of the case main body, the developer layer of the second roller can be thinned. Accordingly, it can be seen that the developer rarely leaks from the case inner surface.

In the above-described configuration, the developer enters the cutout of the layer-thickness regulating member. If the developer remains in the cutout, the developer layer of the second roller cannot be thinned by the cutout. In order to avoid this problem, the fixed member preferably has such a length that enters the cutout during rotation of the first roller.

With this configuration, the developer that enters the cutout is removed by the fixed member, and the gap is ready again. With this technique, developer leakage can be effectively suppressed.

[Aspects of the Invention]

Here, features of a technique described in the following aspects are outlined.

(First Feature) A developer containing case is a developer cartridge that is detachably mounted on a main body of an image forming apparatus (for example, a copy machine, a laser printer, a facsimile machine, a compound machine, or the like) that forms images using a developer.

(Second Feature)If the developer cartridge is mounted on a photosensitive member cartridge, a process cartridge can be constructed. A user can replace only the photosensitive member cartridge or only the developer cartridge. The entire process cartridge can be replaced. The photosensitive member cartridge has a photosensitive member. The developing roller of the developer cartridge comes into contact with the photosensitive member.

(Third Feature) An image forming apparatus having a developer containing case is very useful. The image forming apparatus has a photosensitive member and the developer containing case described above. The developer that is carried on a developing roller of the developer containing case is supplied to the surface of the photosensitive member. Then, the developer supplied to the surface of the photosensitive member is transferred to a recording medium.

(Fourth Feature) A fixed member has a first portion that covers a supply roller shaft, and a second portion that extends from the first portion radially outward an end surface of a supply roller main body. A cutout is provided between the first portion and the second portion. With this cutout, the second portion can be easily bent.

(Fifth Feature) The fixed member comes into contact with a second layer of a side seal member during rotation of the supply roller. With this configuration, the fixed member can scrape off the developer stuck to a side surface of the second layer of the side seal member.

(Sixth Feature) The fixed member comes into contact with the developing roller during rotation of the supply roller. With this configuration, the fixed member can scrape off the developer that tends to enter a gap between the side seal member and the developing roller.

(Seventh Feature) The fixed member is bent while coming into contact with the developing roller. Accordingly, the developer stuck to an edge between a contact surface of the side seal member with the developing roller and a side surface of the side seal member can be scraped off.

An aspect of the invention will be described with reference to the drawing.FIG. 3is a cross-sectional view of a laser printer10according to this aspect. Hereinafter, the laser printer10is simply referred to as a printer10. In this aspect, a right direction ofFIG. 3is referred to as a front side of the printer10.

(Overall Configuration of Laser Printer)

First, the overall configuration of the laser printer10will be simply described.

The printer10has a casing12. The casing12has a plurality of plate members. InFIG. 3, as members forming a portion of the casing12, a rear cover member14, a front cover member16, and the like are shown. The front cover member16is pivotable in a direction of an arrow R1or R2about a shaft18. If the front cover member16pivots in the direction of the arrow R1, the casing12is opened. In this state, a process cartridge40described below can be replaced. If the front cover member16pivots in the direction of the arrow R2, the casing12is closed.

The printer10has a sheet feed device20, a process cartridge40, an exposure device70, a toner fixing device90, and the like. These devices20,40,70, and90are disposed in the casing12. Hereinafter, the devices20,40,70, and90will be described in that order.

(Configuration of Paper Feed Device)

The sheet feed device20has a sheet feed tray22, four rollers28,30,32, and34, and the like. On the sheet feed tray22, printing sheets (not shown) are stacked. The sheet feed tray22has a bottom plate24on which the staked printing sheets are placed.

The sheet feed roller28rotates in a counterclockwise direction. If the sheet feed roller28rotates, an uppermost printing sheet accommodated in the sheet feed tray22is fed in a right direction (an arrow D1). The printing sheet fed in the right direction comes into contact with the roller30. In addition, the printing sheet passes between the rollers32and34. The printing sheet passing between the rollers32and34is fed between two register rollers38along a rail36.

The lower register roller38rotates in a counterclockwise direction. Then, the printing sheet can be fed in a direction of an arrow D2. The upper register roller38is driven through the contact with the printing sheet fed by the lower register roller38and rotates in a clockwise direction.

If the printing sheet is fed in the direction of the arrow D2by the register rollers38, a letter or a drawing is printed on the printing sheet. Specifically, printing is performed by the process cartridge40, the exposure device70, and the fixing device90.

(Configuration of Process Cartridge)

The process cartridge40can be attached to and detached from the casing12. If the front cover member16is opened (the arrow R1), the process cartridge40can be removed from the casing12. An old process cartridge40can be replaced with a new process cartridge40.

The detailed configuration of the process cartridge40will now be described. Here, the configuration will be simply described. The process cartridge40has a casing42. A through hole42ais formed at an upper surface of the casing42. A toner chamber45is formed on a right side in the casing42. A toner is contained in the toner chamber45. Three rollers48,50, and52and a photosensitive drum54are disposed on a left side in the casing42. Each of the rollers48,50, and52and the drum54is connected to a driving source (not shown). The roller48on the right most side is called a supply roller. A developing roller50is disposed on the left side of the supply roller48. The photosensitive drum54is disposed on the left side of the developing roller50. A transfer roller52is disposed below the photosensitive drum54. The printing sheet fed in the direction of the arrow D2by the register rollers38enters between the photosensitive drum54and the transfer roller52. The photosensitive drum54rotates in the clockwise direction, and the transfer roller52rotates in the counterclockwise direction. With the rotation of the photosensitive drum54and the transfer roller52, the printing sheet is further fed in the left direction (the arrow D2). While the printing sheet is fed in the left direction, the toner stuck to the photosensitive drum54is transferred to the printing sheet.

(Configuration of Exposure Device)

The exposure device70is disposed above the process cartridge40. The exposure device70is fixed to the casing12. The exposure device70has a casing72. A through hole72ais formed at a lower surface of the casing72. In the casing72, a polygon mirror74, a reflecting mirror74, a lens78, a reflecting mirror80, and the like are disposed. The exposure device70has a light source (not shown). A laser beam is emitted from the light source. The laser beam supplied from the light source is deflected by the polygon mirror74and goes toward the reflecting mirror78. The laser beam is reflected by the reflecting mirror76and passes through the lens78. The laser beam passing through the lens78is further reflected by the reflecting mirror80. The laser beam reflected by the reflecting mirror80goes downward from the through hole72aoutside the casing72. The laser beam flying out the casing72reaches the photosensitive drum54through the through hole42aof the process cartridge40. Accordingly, the photosensitive drum54is exposed in a predetermined pattern. An arrow L ofFIG. 3represents the above-described trace of the laser beam.

(Configuration of Toner Fixing Device)

Next, the configuration of the toner fixing device90will be described. The toner fixing device90is disposed on a rear side of the process cartridge40(a left side ofFIG. 3). The toner fixing device90has a frame92, a heating roller94, and a pressing roller96.

The frame92rotatably supports the heating roller94and the pressing roller96. The heating roller94has a metal tube94aand a halogen lamp94bthat is disposed in the metal tube94a. The halogen lamp94bheats the metal tube94a. The heating roller94rotates in the clockwise direction. The pressing roller96is urged toward the heating roller94by a mechanism (not shown). If the heating roller94rotates in the clockwise direction, the pressing roller96is driven by the heating roller94and rotates in the counterclockwise direction.

The printing sheet passing through the process cartridge40enters between the heating roller94and the pressing roller96. If the heating roller94rotates in the clockwise direction, the printing sheet between the heating roller94and the pressing roller96is fed in the left direction. The printing sheet is heated by the heating roller94that is heated at high temperature. Then, the toner transferred to the printing sheet is fixed by heat. The printing sheet passing through the toner fixing device90is fed left upward (an arrow D3).

(Configuration of Paper Discharge Mechanism)

A feed roller97is disposed immediately below a left end of the frame92. The feed roller97rotates in the counterclockwise direction. The feed roller97further feeds the printing sheet fed through the toner fixing device90left upward. The printing sheet fed left upward by the feed roller97is fed in a right direction along a rail98(an arrow D4).

A pair of sheet discharge rollers100is disposed on a right side of the rail98. The lower sheet discharge roller100rotates in the clockwise direction. If the lower sheet discharge roller100rotates in the clockwise direction, the upper sheet discharge roller100is driven by the lower sheet discharge roller100and rotates in the counterclockwise direction.

The printing sheet fed by the feed roller96enters between the pair of sheet discharge rollers100. If the lower sheet discharge roller100rotates in the clockwise direction, the printing sheet between the two sheet discharge rollers100is fed in the right direction. The printing sheet is fed outside the casing12. A sheet discharge tray110is formed at an upper surface of the casing12. The printing sheet fed outside the casing12is discharged on the sheet discharge tray110.

The overall configuration of the printer10has been simply described. Subsequently, the configuration of the process cartridge40will be described in detail.

(Detailed Configuration of Process Cartridge)

FIG. 4is an enlarged cross-sectional view of the process cartridge40. The process cartridge40has two cartridges43and44. The cartridge43disposed on the right side is called a developer cartridge, and the cartridge44disposed on the left side is called a photosensitive member cartridge. The developer cartridge43and the photosensitive member cartridge44are separatably connected to each other.FIG. 5is a cross-sectional view of the photosensitive member cartridge44after the developer cartridge43is separated. According to the process cartridge40, only the developer cartridge43can be replaced and only the photosensitive member cartridge44can be replaced. Further, the entire process cartridge40can be replaced.

(Configuration of Photosensitive Member Cartridge)

The configuration of the photosensitive member cartridge44will be described. The photosensitive member cartridge44has a casing44a. A through hole44a, through which the laser beam passes, is formed at an upper surface of the casing44a. An introduction hole44b, which the printing sheet enters, is formed at a lower surface of the casing44a. Further, a delivery hole44c, through which the printing sheet is delivered, is formed at a left side surface of the casing44a. The printing sheet enters the photosensitive member cartridge44, passes between the photosensitive member cartridge44and the transfer roller52, and is delivered from the delivery hole44c.

The photosensitive drum54, the transfer roller52, and a charger66are disposed in the casing44aof the photosensitive member cartridge44.

The photosensitive drum54comes into contact with the developing roller50on the left side of the developing roller50. The photosensitive drum54has a drum main body54aand a drum shaft54b. The drum main body54ahas a cylindrical shape. The drum main body54ais a positively chargeable photosensitive member. The drum main body54ais rotatably attached to the drum shaft54b. The drum shaft54bis fixed to the casing44aof the photosensitive member cartridge44. The drum main body54ais connected to a driving source (not shown). The drum main body54arotates in the clockwise direction.

The transfer roller52comes into contact with the photosensitive drum54on the lower side of the photosensitive drum54. The transfer roller52has a transfer roller main body52aand a transfer roller shaft52b. The transfer roller main body52ahas a cylindrical shape that covers the transfer roller shaft52b. The transfer roller shaft52bis rotatably supported on the casing44aof the photosensitive member cartridge44. The transfer roller52rotates in the counterclockwise direction. The transfer roller shaft52bis connected to a voltage supply circuit (not shown). Upon transfer (when the toner attached to the photosensitive drum54is transferred to the printing sheet), a bias is applied from the voltage supply circuit to the transfer roller52.

The charger66is disposed above the photosensitive drum54. A gap is provided between the charger66and the photosensitive drum54. The charger66is a Scorotron type. The charger66has a discharge wire66aand a grid66b. The discharge wire66aextends in a direction perpendicular to the sheet ofFIG. 4. A high voltage is applied to the discharge wire66a. The grid66bis disposed between the discharge wire66aand the photosensitive drum54. A bias voltage is applied to the grid66b. Accordingly, a discharge amount of the discharge wire66ais adjusted. The high voltage is applied to the discharge wire66aso as to cause a corona discharge, and the bias voltage is applied to the grid66b. Then, the surface of the photosensitive drum54(the drum main body54a) is positively charged.

(Configuration of Developer Cartridge)

Next, the configuration of the developer cartridge43will be described. The developer cartridge43has a case main body43a. The toner chamber45is formed in the case main body43a. The toner chamber45contains the toner. In this aspect, a positively chargeable non-magnetic single-component toner is used. For example, there is used a polymerized toner obtained by suspended-polymerizing a polymerizing monomer, for example, a styrene-based monomer, acrylic-based monomer, or the like. A sacrylic-basemonomer, acrylicacid, alkyl (C1 to C4) acrylate, alkyl (C1 to C4) metaacrylate, or the like can be adopted. Such a polymerized toner is substantially globular and exhibits excellent fluidity. A coloring agent or a wax is mixed in the polymerized toner. In addition, an additive, such as silica, is added to the toner in order to improve fluidity. An agitator46is accommodated in the toner chamber45. The agitator46is rotatably supported on the case main body43aabout a shaft46a. If the agitator46rotates in the clockwise direction, the toner in the toner chamber45is stirred. Accordingly, the toner is supplied to the supply roller48.

An opening43bis formed at a left surface of the case main body43a. The opening43bextends in the direction perpendicular to the sheet inFIG. 4. The supply roller48is disposed on the right side of the opening43b. The developing roller50is disposed on the left side of the opening43b. The supply roller48and the developing roller50are positioned at positions facing the opening43b.

The supply roller48has a supply roller main body48a, a supply roller shaft48b, and a fixed member180(which is not shown inFIG. 4but shown inFIG. 6) and the like. The supply roller main body48ahas a cylindrical shape that covers the supply roller shaft48b. The supply roller main body48ais formed of a conductive foam material. The supply roller shaft48bis formed of a metal. The supply roller shaft48bis rotatably supported on the case main body43aof the developer cartridge43. The supply roller48rotates in the counterclockwise direction. The fixed member180will be described in detail below.

The developing roller50is positioned outside the case main body43athan the supply roller48does. The developing roller50strongly comes into contact with the supply roller48. The developing roller50has a developing roller main body50aand a developing roller shaft50b. The developing roller main body50ahas a cylindrical shape that covers the developing roller shaft50b. The developing roller main body50ais formed of a conductive rubber material. As the rubber material, conductive urethane rubber or silicon rubber containing carbon particles or the like can be adopted. The developing roller shaft50bis formed of a metal. The voltage supply circuit (not shown) is connected to the developing roller shaft50b. Upon development (when the toner is attached to the photosensitive drum54), a bias is applied from the voltage supply circuit to the developing roller50. The developing roller shaft50bis rotatably supported on the case main body43a. The developing roller50rotates in the counterclockwise direction.

A layer-thickness regulating member47is fixed to the case main body43a. The layer-thickness regulating member47is disposed on the left side of the opening43b. The layer-thickness regulating member47extends in the direction perpendicular to the sheet inFIG. 4and comes into contact with the developing roller50. The layer-thickness regulating member47regulates (adjusts) the thickness of a toner layer formed on the surface of the developing roller50.

FIG. 6is a front view simply showing the developer cartridge43as viewed from a VI direction ofFIG. 4.FIG. 6does not show the photosensitive member cartridge44. InFIG. 6, the developing roller50is indicated by a broken line. The developing roller50extends in a left and right direction at a position facing the opening43bof the case main body43a. The layer-thickness regulating member47is fixed to an upper portion of the case main body43a. The layer-thickness regulating member47extends in the left and right direction.

Regions140that oppose the rotary surface of the developing roller50(a circumferential surface of the developing roller main body50a) exist at left and right ends of the case main body43a. Side seal members150are adhered to the opposing regions140of the case main body43a, respectively.

FIG. 7is a perspective view showing a vicinity of a right end of the developer cartridge43(a right end ofFIG. 6). The configuration of the right end of the developer cartridge43will be described in detail. Since a left end of the developer cartridge43is made by inverting the right end of the developer cartridge43in the left and right direction, and thus the detailed description thereof will be omitted. InFIG. 7, for better understanding of the configuration of the layer-thickness regulating member47, a portion of a frame member160adescribed below is cut.

InFIG. 7, the developing roller50is not shown. A hole143afor rotatably supporting the developing roller50is provided at the right end of the case main body43a. The developing roller shaft50b(seeFIG. 4) extends outward (rightward inFIG. 7) beyond the hole143a.

A lower seal member152is adhered to a lower frame43cof the case main body43a. The lower seal member152extends over the substantially entire region of the case main body43ain a left and right direction (in a left and right direction ofFIG. 6). InFIG. 6, this example is well shown.

FIG. 8is a cross-sectional view taken along the line VIII-VIII ofFIG. 7. InFIG. 8, the developing roller50is indicated by a broken line. An arrow indicated by a broken line represents a rotation direction of the developing roller50.

The configuration of the side seal member150will be described. The side seal member150has a two-layered structure. A lower layer150aof the side seal member150is bonded to the opposing region140(seeFIG. 6) of the case main body43a. The lower layer150ais formed of sponge. An upper layer150bof the side seal member150is laminated on the lower layer150a. The upper layer150bis formed of felt. The upper layer150bcomes into contact with the rotary surface of the developing roller50.

The upper layer150bextends upward beyond the lower layer150a. A portion that extends upward beyond the lower layer150ais bonded to a sponge layer150c.

The lower layer150aand the sponge layer150care formed of elastically deformable sponge, and thus the upper layer150bstrongly comes into contact with the developing roller50. Accordingly, a high shield effect can be obtained.

Next, the configuration of the layer-thickness regulating member47will be described in detail. The layer-thickness regulating member47has a holding member160and a contact member162. The holding member160holds the contact member162. The contact member162is not shown in the cross-sectional view ofFIG. 8but is shown inFIG. 7. The contact member162extends in the rotary shaft direction of the developing roller50and comes into contact with the substantially entire region in the rotary shaft direction of the developing roller50. The contact member162is formed of rubber.

The holding member160has two frame members160aand160band a stainless plate160c. The front frame member160a(a left side inFIG. 8) has a substantially L shape. The stainless plate160cis interposed between the front frame member160aand the rear frame member160b. The two frame members160aand160band the stainless plate160cextend in the rotary shaft direction of the developing roller50(a direction perpendicular to the sheet inFIG. 8). As shown inFIG. 7, the contact member162is bonded to the stainless plate160c. The contact member162is not bonded to the left and right ends (the left and right ends ofFIG. 6) of the stainless plate160c. The side seal member150(portions of the sponge layer150cand the upper layer150b) is bonded to those ends.

A sponge member164is disposed between the case main body43aand the rear frame member160b. The sponge member164extends in the rotary shaft direction of the developing roller50. The sponge member164seals between the case main body43aand the frame member160b. A sponge member166is also disposed between the sponge member164and the stainless plate160c. The sponge member166also extends in the rotary shaft direction of the developing roller50and functions as a sealant.

An elastic member (for example, sponge)168that buries a vicinity of the supply roller shaft48bis disposed at a lower portion of the case main body43a. The side seal member150is also bonded to the sponge168.

Returning toFIG. 7, the configuration of a vicinity of the fixed member180of the supply roller48will be described. As shown inFIG. 7, the supply roller48has the fixed member180. A gap G1is formed between an end surface170of the supply roller main body48aand an inner surface190of the case main body43a. The fixed member180is disposed so as to partially occupy the gap G1. The end surface170of the supply roller main body48ais flat.

FIG. 9shows the inner surface190of the case main body43aand the side seal member150as viewed from an IX direction ofFIG. 7. InFIG. 9, the supply roller48is indicated by a broken line. As shown inFIG. 9, the end surface170of the supply roller main body48aopposes the inner surface190of the case main body43aand the side seal member150. Further, the fixed member180has such a length that reaches the developing roller50(a radial length of the end surface170of the supply roller main body48a). In a state shown inFIG. 9, since the fixed member180and the developing roller50come into contact with each other, the fixed member180is bent.

FIG. 10shows the end surface170of the supply roller main body48a. As shown inFIG. 10, an exposed portion of the supply roller shaft48b(a portion protruding from the supply roller main body48a) has a substantially D shape as viewed from a direction parallel to the sheet ofFIG. 10. This example is also shown inFIG. 8. An unexposed portion of the supply roller shaft48bhas a columnar shape.

The fixed member180is formed of resin (specifically, polypropylene resin). The fixed member180has a portion182that is formed in a shape corresponding to the D shape of the supply roller shaft48b, and a portion184that extends upward from the portion182. The fixed member180is fixed to the supply roller shaft48bby fitting the portion182on the supply roller shaft48b.

FIG. 11is an enlarged view of a region XI ofFIG. 10. A cutout186is formed between the portion182and the portion184. As viewed from a direction perpendicular to the sheet ofFIG. 11, the cutout186has a substantially circular shape. The cutout186is formed in the fixed member180over the entire region in the direction perpendicular to the sheet ofFIG. 11. Since the cutout186is provided, the portion184can be easily bent in a right direction ofFIG. 11(in the clockwise direction).

As will be apparent fromFIG. 10, the portion184of the fixed member180has a rectangular shape that extends from the supply roller shaft48bradially outward the end surface170of the supply roller main body48a. The portion184extends outward (upward in a state ofFIG. 10) beyond the end surface170of the supply roller main body48a. The fixed member180has a length (a radial length of the end surface170of the supply roller main body48a) so as not to come into contact with the layer-thickness regulating member47(seeFIG. 7) even though the supply roller48rotates. Meanwhile, the fixed member180has a length so as to come into contact with the developing roller50or the lower frame43cduring the rotation of the supply roller48. The cutout186(seeFIG. 11) is provided in the fixed member180such that the fixed member180comes into contact with the developing roller50or the like to be then easily bent. If the fixed member180comes into contact with the developing roller50or the lower frame43c, the portion184is bent.

The fixed member180has a width (a width in the left and right direction ofFIG. 6) equal to a distance between the end surface170of the supply roller main body48aand the inner surface190of the case main body43a(seeFIG. 7). That is, the fixed member180comes into contact with the end surface170of the supply roller main body48aand the inner surface190of the case main body43a. Further, the fixed member180comes into contact with the upper layer150band the lower layer150aof the side seal member150.

(Action of Process Cartridge)

The configuration of the process cartridge40will be described in detail. Subsequently, the action of the process cartridge40having the above-described configuration will be described with reference toFIG. 4again.

The toner in the toner chamber45is attached to the supply roller48. The toner attached to the supply roller48is positively charged by friction between the supply roller48and the developing roller50. The positively charged toner covers the surface of the developing roller50. The contact member162of the layer-thickness regulating member47(seeFIG. 7) comes into contact with the toner layer on the surface of the developing roller50. Accordingly, the toner layer is adjusted to have a constant thickness.

Meanwhile, the surface of the drum main body54ais positively charged by the charger66. The positively charged surface of the drum main body54areceives the laser beam emitted from the exposure device70(seeFIG. 3). Accordingly, a predetermined portion of the surface of the drum main body54ais exposed. A potential of the exposed portion of the drum main body54afalls. A portion to be exposed varies according to a printing content. An electrostatic latent image on the basis of the printing content is formed on the drum main body54a.

The toner covering the developing roller50is attached to the exposed portion of the drum main body54a. At this time, the toner is not attached to the unexposed portion of the drum main body54a. Accordingly, the electrostatic latent image formed on the drum main body54abecomes a visual image.

The visual image carried on the drum main body54ais transferred to the printing sheet between the photosensitive drum54and the transfer roller52. At this time, a bias is applied to the transfer roller52. The toner is transferred to the printing sheet by a potential difference between the photosensitive drum54and the transfer roller52.

Through the above-described processes, a desired image (a letter or a drawing) is printed on the printing sheet.

In this aspect, the gap G1is provided between the end surface170of the supply roller main body48aand the inner surface190of the case main body43a(seeFIG. 7). The toner that moves from the supply roller main body48ain the rotary shaft direction enters the gap G1. Since the gap G1is provided, the toner can be suppressed from directly moving from the supply roller main body48ato the inner surface190of the case main body43a.

The supply roller48has the fixed member180that partially occupies the gap G1. The fixed member180rotates integrally with the supply roller shaft48b. Accordingly, the fixed member180scrapes off the toner entering the gap G1.

As will be apparent fromFIG. 7or10, the fixed member180is configured to have a very small volume as compared with a volume of the gap G1. The volume of the fixed member180is at least half or less of the volume of the gap G1. Since the volume of the fixed member180is small, the volume of the gap G1is secured large.

The fixed member180extends from the end surface170of the supply roller main body48ato the inner surface190of the case main body43a. Further, the fixed member180extends outward beyond the end surface170of the supply roller main body48afrom the supply roller shaft48b. With this configuration, the fixed member180during the rotation can pass through the entire region of the gap G1. Therefore, the fixed member180can scrape off the toner over the entire region of the gap G1.

If the fixed member180is not provided, the toner remains in the gap G1. In this case, the toner remaining in the gap G1may enter a narrow gap G2(seeFIG. 9) between the side seal member150and the developing roller150. If the toner moves in the gap G2, the toner may leak from the case main body43a. In this aspect, since the fixed member180is provided, the toner does not remain in the gap G1. Therefore, the toner can be prevented from remaining near the inner surface190of the case main body43a. Further, the toner can be prevented from entering the gap G2.

As shown inFIG. 9, the fixed member180has such a length (the radial length of the end surface170of the supply roller main body48a) that reaches the upper layer150bof the side seal member150. For this reason, the fixed member180can scrape off the toner attached to the side surface of the upper layer150b. Further, the fixed member180has such a length that comes into contact with the developing roller50. The fixed member180comes into contact with the developing roller50to be then bent. Since the fixed member180rotates while being bent, it is possible to successfully scrape off the toner that is being attached to the edge between the contact surface of the side seal member150with the developing roller50and the side surface of the side seal member150. The fixed member180can scraped off the toner that tends to enter between the upper layer150bof the side seal member150and the developing roller50.

According to the technique of this aspect, the toner can be effectively suppressed from leaking from the developer cartridge43.

FIG. 12shows a supply roller48according to a second aspect of the invention. Here, only different parts from those of the first aspect will be described.

In this aspect, a fixed member210has a portion212that is fixed in the vicinity of the supply roller shaft48b, and a portion214that extends upward from the portion212. The portion212has the same configuration as the first aspect. An upper end of the portion214is bent in advance in a right direction ofFIG. 12(in a clockwise direction). This is different from the first aspect. The portion214is bent in a reverse rotation direction of the supply roller48.

Like this aspect, even though the fixed member210is bent in advance, it is possible to successfully scrape off the toner that is being attached to the edge between the contact surface of the side seal member150with the developing roller50and the side surface of the side seal member150.

FIG. 13is a front view showing a portion of a developer cartridge43according to a third aspect of the invention. Here, only different parts from those in the first aspect will be described.

In this aspect, the configuration of the layer-thickness regulating member47is different from the first aspect. A cutout250is formed in the stainless plate160cand the contact member162. The cutout250is provided at a position corresponding to an end (a right end ofFIG. 13) in the rotary shaft direction of the developing roller50(not shown). With this configuration, a contact area of the contact member162with the developing roller50is larger in a portion other than the cutout250and is smaller in the cutout250. If the contact area is large, a low pressure is applied from the contact member162to the developing roller50, and the toner layer of the developing roller50is thicker. If the contact area is small, a high pressure is applied from the contact member162to the developing roller50, and the toner layer of the developing roller50is thinner.

The cutout250is provided at a position corresponding to the end of the developing roller50in the rotary shaft direction. For this reason, at the end of the developing roller50in the rotary shaft direction, the toner layer is thinner. Then, the end of the developing roller50in the rotary shaft direction is close to the inner surface190of the case main body43a(seeFIG. 7). With this configuration, the toner layer of the developing roller50can be thinner near the inner surface190of the case main body43a.

If a large amount of the toner exists near the inner surface190of the case main body43a, there is a high possibility that the toner leaks from the inner surface190of the case main body43a. With the configuration of this aspect, the toner layer of the developing roller50near the inner surface190of the case main body43acan be thinner. Further, a state where a large amount of the toner exists near the inner surface190of the case main body43acan be avoided.

In the above-described configuration, the toner may enter the cutout250. If the toner enters the cutout250, the toner may remain near the inner surface190of the case main body43a. In this case, toner leakage tends to occur. In order to avoid this situation, the fixed member280of this aspect has such a length that enters the cutout250during the rotation of the supply roller48.FIG. 13shows a state where the fixed member280enters the cutout250.

According to this aspect, the fixed member280enters the cutout250, and thus the toner entering the cutout250can be scraped off. Therefore, toner leakage can be effectively suppressed.

FIG. 14is a perspective view showing a portion of a supply roller48according to a fourth aspect of the invention. Here, only different parts from those in the first aspect will be described.

In the first aspect, the fixed member180(seeFIG. 7) is formed separately from the supply roller main body48a. In contrast, in this aspect, fixed members380aand380bare formed integrally with the supply roller main body48a. The supply roller main body48aand the fixed members380aand380bare formed by cutting a material (a foam material).

A thickness G3of each of the fixed members380aand380bis consistent with a distance between the end surface170of the supply roller main body48aand the inner surface190of the case main body43a(seeFIG. 7). That is, the fixed members380aand380bcome into contact with the inner surface190of the case main body43aand the side seal member150.

In this aspect, a pair of fixed members380aand380bis provided symmetrically about the supply roller shaft48b.FIG. 15is a diagram as viewed from a XV direction ofFIG. 14. As shown inFIG. 15, each of the fixed members380aand380bhas a rectangular shape that extends from the supply roller shaft48bradially outward.

With this aspect, the supply roller main body48aand the fixed members380aand380bcan be formed of one material. Therefore, the number of kinds of material required for forming the developer cartridge43can be reduced.

As described above, illustrative aspects of the invention have been described in detail in the foregoing, but these are merely an illustration and do not limit the scope described in the appended claims. Various modifications and changes of the illustrative aspects in the foregoing are included in the techniques described in the appended claims.

(1) The shape of the fixed member can be changed. For example, a shape shown inFIG. 16can be adopted.FIG. 16is a diagram showing an end surface170of a supply roller main body48aaccording to this modification in front view. As shown inFIG. 16, each of fixed members390aand390bmay have a sectoral shape that is widened from a supply roller shaft48bradially outward.

(2) Further, for example, a shape shown inFIG. 17can be adopted.FIG. 17is a diagram showing an end surface170of a supply roller main body48aaccording to this modification in front view. In this modification, each of fixed members400ato400fhas a vane shape that extends from a supply roller shaft48bradially outward. With this shape, the toner can be effectively scraped off.

(3) A material of the fixed member can be changed to a material other than resin. For example, PET or the like can be adopted. Further, the fixed member may be formed of felt, like the upper layer150bof the side seal member150. In this case, the upper layer150bof the side seal member150and the fixed member can be formed of the same material. Therefore, the number of kinds of material required for forming the developer cartridge43can be reduced.

(4) A size of the fixed member can be changed. For example, the fixed member may not come into contact with the supply roller main body48a. Further, the fixed member may not come into contact with the inner surface190of the case main body43a. Furthermore, the fixed member may not be beyond the end surface170of the supply roller main body48a. For example, the fixed member may have a length shorter than a radius of the end surface170of the supply roller main body48a.

In addition, the technical elements described in this specification or the drawings exert their technical availability, alone or by various combinations, so that they are not limited to the combinations described in the claims. Also, the techniques exemplified in this specification or the drawings can attain two or more objects simultaneously, and attainment of one object among them has by itself has a technical availability.

(Configuration of Developing Cartridge)

As shown inFIG. 18, a developing cartridge1026includes a toner case1036serving as a developer containing case, and a toner containing chamber1037, a supply roller1038, a developing roller1039, and a blade unit4100serving as a layer-thickness regulating blade that are disposed in the toner case1036.

The toner case1036is formed in a box shape having a longitudinal opening1041at its rear end. Specifically, as shown inFIGS. 18 and 19, the toner case1036has an upper wall1042and a lower wall1043that face each other in the up and down direction, a pair of side walls1044that closes a gap between the upper wall102and the lower wall1043from both sides in the widthwise direction, and a front wall1079that is provided to close a gap between the upper wall1042and the lower wall1043from the front side.

As shown inFIG. 18, the upper wall1042has a partition plate1045that extends from a portion close to the rear side toward the lower wall1043in the front-to-rear direction. An internal space of the toner case1036is partitioned by the partition plate1045, and an internal space on the front side forms the toner containing chamber1037. Further, a blade attaching portion1046that attaches the blade unit1040thereto is provided at the rear end of the upper wall1042. The blade attaching portion1046, the lower wall1043, and the pair of side walls1044define the longitudinal opening1041that extends in the widthwise direction. Moreover, a direction in which the toner containing chamber1037and the opening1041are connected to each other is referred to as a connection direction. That is, in this embodiment, the connection direction and the front-to-rear direction are consistent with each other. In addition, a longitudinal direction of the opening1041is referred to as a widthwise direction.

As shown inFIG. 18, the blade attaching portion1046substantially has an L-shaped side section. Specifically, the blade attaching portion1046includes a plate-shaped top attaching portion1047that faces the lower wall1043, extends in the widthwise direction, and has a width in the front-to-rear direction, and a front attaching portion1048that is bent from a front end of the top attaching portion1047downward, extends in the widthwise direction, has a width in the up and down direction, and has concave portions formed in a lattice shape in bottom view.

As shown inFIG. 19, a plurality of concave portions1082are formed in the front attaching portion1048by cutting a longitudinal lower edge in a semicircle shape. Accordingly, collision against an assembling screw (not shown) that is inserted from the inside of the toner case1036toward the opening1041is avoided. Further, in the front attaching portion1048, screw holes1083are formed at an interval from the concave portions1082longitudinally outward. When the blade unit1040is attached to the blade attaching portion1046(the front attaching portion1048), attaching screws1094described below are screwed into the screw holes1083. Then, a blade support plate1049is provided so as to fix the blade unit1040from the back side of the front attaching portion1048in bottom view, together with the front attaching portion1048. A longitudinal direction of the blade support plate1049is formed to be slightly shorter than the length of the opening1041in the widthwise direction. Cutouts1049aare formed at both ends of the blade support plate1049so as to prevent the toner stirred by a toner stirring gear1106serving as a rotary member described below from retaining. Further, an up and down direction of the blade support plate1049extends below the front attaching portion1048in order to support the lower end of the blade unit1040.

As shown inFIG. 18, the front end of the lower wall1043extends obliquely above the front side and is connected to the front wall1079. Further, a film disposing portion1121is formed at a top surface on the rear side of the lower wall1043to extend in the axial direction of the developing roller1039. A lower film1122that is formed of polyethylene terephthalate and uniformly rubs the peripheral surface of a roller1056of the developing roller1039in the axial direction is disposed on the film disposing portion1121. The lower film1122uniformly rubs the peripheral surface of the roller1056of the developing roller1039in the axial direction below the lower wall1043, such that toner leakage between the lower wall1043and the developing roller1039can be prevented. In addition, as shown inFIG. 19, a plurality of ribs1103are formed at the bottom surface of the lower wall1043at intervals in the widthwise direction to extend in the front-to-rear direction. The ribs1103that are formed at both ends of the bottom surface of the lower wall1043serve as guide portions that extend in the front-to-rear direction along inner edges in the widthwise direction of bottom surfaces1102of seal disposing portions1096described below and fit and dispose a felt seal member1093described below.

As shown inFIG. 19, each of the side walls1044has, in the opening1041, a support plate1095that supports the developing roller1039and the seal disposing portions1096on which a side seal1091serving as a seal member described below is disposed.

The support plate1095has a plate shape extending in the up and down direction, and shaft receiving holes1097are formed therein so as to receive a roller shaft1055of the developing roller1039described below. Each of the shaft receiving hole1097has a U shape in side view and an end of the rear side is opened, such that the roller shaft1055of the developing roller1039can be received through the opening.

The seal disposing portions1096have roller opposing surfaces1098that are provided adjacent to both ends in the widthwise direction of the opening1041relative to the support plates1095, face axial ends of the roller1056of the developing roller1039described below and adhered portions84of a plate spring member1057of the blade unit1040, and extend in curved shapes along an outer peripheral surface of the roller1056. In addition, concave portions1099that receive a roller shaft1053of the supply roller1038described below are formed to be depressed obliquely forward in the up and down direction of the seal disposing portions1096.

A positively chargeable non-magnetic mono-component toner is contained in the toner containing chamber1037. As a toner, there is used a polymerized toner obtained by polymerizing a polymerizing monomer, for example, a styrene-based monomer of styrene or the like, acrylic-based monomer of acrylic acid, alkyl (C1 to C4) acrylate, alkyl (C1 to C4) metaacrylate or the like by a known polymerization method, such as suspension polymerization or the like. Such a polymerized toner is substantially globular and exhibits excellent fluidity, such that it is possible to achieve image formation of high image quality. A coloring agent, such as carbon black or the like, or a wax is mixed in the toner. In addition, an additive, such as silica, is added to the toner in order to improve fluidity. The average particle diameter of the toner is in a range of about 6 to 10 μm.

An agitator1050is provided in the toner containing chamber1037so as to stir the toner in the toner containing chamber1037. The agitator1050is supported by a rotary shaft1051extending in the widthwise direction at a central portion of the toner containing chamber1037and rotates with the rotary shaft1051as a fulcrum. Then, the toner in the toner containing chamber1037is stirred and discharged from a connection port1052between the partition plate1045and the lower wall1043toward the rear side.

As shown inFIG. 18, the supply roller1038is disposed below the connection port1052obliquely rearward, and is rotatably supported between the pair of side walls1044of the toner case1036so as to extend toward the opening1041. A roller1054of the supply roller1038is provided at a gap from the seal disposing portions1096formed on both sides in the widthwise direction of the opening1041such that both longitudinal ends do not come into contact with the side seal1091serving as a seal member described below. The supply roller1038is formed by coating the metal roller shaft1053with the roller1054formed of a conductive foam material. As shown inFIG. 20, a connection gear1105serving as a connection member described below is provided in a gap between the roller1054and the seal disposing portion1096to be inserted into the roller shaft1053of the supply roller1038. The connection gear1105transfers a driving force of the supply roller1038to a toner stirring gear1106serving as a rotary member described below.

As shown inFIGS. 18 and 19, the developing roller1039is disposed in the opening1041in the widthwise direction on the rear side of the supply roller1038and is rotatably supported between the support plates1095of the pair of side walls1044of the toner case1036. Further, the developing roller1039faces and comes into contact with the photosensitive drum1028in the front-to-rear direction in a state where a portion of the surface of the developing roller1039is disposed to protrude rearward from the opening1041of the toner case1036to be then exposed, and the developing cartridge1026is mounted on the drum cartridge1025. The developing roller1039is formed by coating the metal roller shaft1055with the roller1056formed of a conductive rubber material. In the roller1056of the developing roller1039, the surface of a roller layer formed of conductive urethane rubber or silicon rubber containing carbon particles is coated with a coat layer formed of urethane rubber or silicon rubber containing fluorine. Further, the roller1056of the developing roller1039is disposed to come into contact with the roller1054of the supply roller1038such that both rollers are compressed.

As indicated by an arrow, a portion of the supply roller1038that comes into contact with the developing roller1039rotates in a counterclockwise direction from the above toward the below. Further, as indicated by an arrow, a portion of the developing roller1039that is exposed from the toner case1036rotates in a counterclockwise direction from the above toward the below.

Next, the configuration of the blade unit.1040will be described with reference toFIGS. 18 to 21.FIG. 21is a front view of the blade unit as viewed from the opening.

As shown inFIGS. 18 and 21, the blade unit1040includes a plate spring member1057, a warp preventing member1058and a reinforcing plate1059that support the plate spring member1057, and a plurality of assembling screws (not shown) that fix them to one another. The individual parts constituting the blade unit1040are formed of a rigid material, that is, a metal. As described below, the blade unit1040is attached such that the reinforcing plate1059faces the front attaching portion1048and the blade support plate1049in a state where the plate spring member1057is interposed between the warp preventing member1058and the reinforcing plate1059.

The plate spring member1057is formed of a thin metal plate spring material, and is formed in a rectangular shape having the substantially same width as the width in the widthwise direction of the roller1056of the developing roller1039. An upper end of the plate spring member1057is interposed between the warp preventing member58and the reinforcing member1059. Further, as shown inFIGS. 20 and 21, a pressing rubber member1060serving as a layer-thickness regulating unit is provided at a lower end of the plate spring member1057to extend in a longitudinal direction of the plate spring member1057. The pressing rubber member1060is formed of an insulating silicon rubber and has a lower edge1060ahaving a curvature R. The pressing rubber member1060has a rectangular sectional shape. The pressing rubber member1060is not formed at both longitudinal ends of the plate spring member1057. The adhered portions1084, to which the upper end of the felt seal member1093described below is adhered, are formed at both longitudinal ends. The lower edge1060aof the pressing rubber member1060does not extend over the adhered portions1084in the longitudinal direction, and both longitudinal ends form cutouts1060b. The cutouts1060bare formed by cutting the lower edge1060ahaving the curvature R at both ends of the plate spring member1057. Portions of the cutouts1060bpressed into contact with the developing roller1039do not have the curvature R, but have a predetermined angle.

At positions facing screw holes described below in the front-to-rear direction in the longitudinal direction of the plate spring member1057, a plurality of insertion holes1100, into which the individual assembling screws are inserted, are formed to pass through the plate spring member1057in a thicknesswise direction. The insertion holes1100are disposed inside both edges of the pressing rubber member1060in the longitudinal direction of the plate spring member1057. On both outer sides of the insertion holes in the longitudinal direction of the plate spring member1057, attaching holes (not shown), into which the attaching screws1094are inserted, are formed to pass through the plate spring member1057in the thicknesswise direction. The attaching holes are formed at positions corresponding to the screw holes1083formed in the front attaching portion1048of the blade attaching portion1046in the front-to-rear direction.

The warp preventing member1058extends in the longitudinal direction of the plate spring member1057and is disposed to face the upper end of the surface of the plate spring member1057.

The reinforcing plate1059is formed of a metal plate having a slender rectangular shape. The reinforcing plate1059is formed to extend in the longitudinal direction of the plate spring member1057and to be shorter than each of the attaching holes of the plate spring member1057. On the back surface of the plate spring member1057, the reinforcing plate1059faces the warp preventing member1058with the plate spring member1057interposed therebetween. Then, the reinforcing plate1059supports and reinforces the plate spring member1057in a state where the upper end of the plate spring member1057is interposed between the plate spring member1057and the warp preventing member1058. At both longitudinal ends of the reinforcing plate1059, screws holes (not shown), in which the assembling screws are respectively screwed, are formed. The plate spring member1057, the warp preventing member1058, and the reinforcing plate1059are fixed to one another by the plurality of assembling screws.

As shown inFIG. 18, the blade unit1040is attached to face the blade attaching portion1046, and the warp preventing member1058is attached to face the upper attaching portion1047. Further, the reinforcing plate1059is attached to face the front attaching portion1048and the blade support plate1049. A sponge member1061fixes the front attaching portion1048to the blade support plate1049, and a sponge member1062fixes the lower end of the plate spring member1057to the sponge member1061. As a result, the blade unit1040is reliably fixed to the front attaching portion1048and the blade support plate1049. The sponge members61and62bury gaps between the blade unit1040, and the front attaching portion1048and the blade support plate1049, thereby to prevent the toner from entering the gaps.

In a state where the blade unit1040is attached to the blade attaching portion1046, the lower end of the plate spring member1057faces the roller1056of the developing roller1039from the front side, and the pressing rubber member1060is pressed into contact with the roller1056by an elastic force of the plate spring member1057. The toner discharged from the connection port1052into the internal space on the rear side of the toner case1036by the rotation of the agitator1050is supplied onto the roller1056of the developing roller1039by the rotation of the supply roller1038. At this time, the toner is positively frictionized and charged between the roller1054of the supply roller1038and the roller1056of the developing roller1039. The toner supplied onto the roller1056of the developing roller1039enters between the pressing rubber member1060of the blade unit1040and the roller1056of the developing roller1039according to the rotation of the developing roller1039and then is frictionized and charged. Then, the toner of a thin layer having a predetermined thickness is formed and carried on the roller1056of the developing roller1039.

As shown inFIG. 20, since the lower edge1060ahas the curvature R, the lower edge1060aof the pressing rubber member1060and the developing roller1039come into planar contact with each other, a pressing force against the developing roller1039at the lower edge1060ais dispersed. Accordingly, at a portion where the lower edge1060aand the developing roller1039come into contact with each other, the toner of a thin layer having a predetermined thickness is formed and carried on the roller1056of the developing roller1039. Meanwhile, since the cutout1060bclose to the developing roller1039has a predetermined angle, the cutout1060bof the pressing rubber member1060and the developing roller1039come into linear contact with each other, and thus a pressing force against the developing roller1039at the cutout1060bis concentrated. Accordingly, at a portion where the cutout1060band the developing roller1039come into contact with each other, the toner on the roller1056is almost scraped. Therefore, the toner is not almost carried on both longitudinal ends of the roller1056of the developing roller1039. As a result, it is possible to prevent leakage of the toner carried on both longitudinal ends of the roller1056from a gap between the roller1056and the side seal1091described below coming into contact with both longitudinal ends of the roller1056, a gap between the side seal1091and both longitudinal ends of the pressing rubber member1060, and the like.

(Configuration of Side Seal)

Next, the configuration of the side seal1091will be described with reference toFIGS. 22 and 23.FIG. 22is a side sectional view showing the configuration of the opening of the toner case.FIG. 23is a bottom view of the toner case1036showing a vicinity of a toner stirring mechanism1104.FIG. 23shows the toner caser1036in a state where the developing roller1039is removed.

As shown inFIGS. 22 and 23, in the developing cartridge1026, a side seal1091serving as a seal member for preventing leakage of the toner from both axial ends of the developing roller1039is disposed at a roller opposing surface1098of the seal disposing portion96of each side wall1044. The side seal1091is provided to rub the surface of the roller1056at both axial ends of the roller1056of the developing roller1039. The side seal1091has a sponge seal member1092and a felt seal member1093that is deposited on the sponge seal member1092.

The sponge seal member1092is formed of a sponge material, such as urethane foam or the like. More specifically, among sponge materials, a sponge material (trade name: PORON, manufactured by Rogers Inoac Corporation) of urethane foam having a relatively high hardness is used. The sponge seal member1092is disposed on the roller opposing surface1098of the seal disposing portion1096to extend in the up and down direction along the rotation direction of the developing roller1039. An upper end surface of the sponge seal member1092on a downstream side of the rotation direction is connected adjacent to a lower end surface of a blade back seal1087closing a gap of the blade attaching portion46to which the blade unit1040is attached. A lower end surface of the sponge seal member1092on an upstream side of the rotation direction is flush with a rear end surface1101of the seal disposing portion1096in the front-to-rear direction. The upper end of the sponge seal member1092is interposed between the plate spring member1057and the seal disposing portion1096. The sponge seal member1092is adhered to the roller opposing surface1098of the seal disposing portion1096by a double-faced adhesive tape.

As shown inFIGS. 22 and 23, the felt seal member1093is formed of felt containing a polyester-based fiber. The felt seal member1093is attached to extend along the sponge seal member1092over the adhered portions1084of the plate spring member1057and the sponge seal member1092, to pass through a rear end surface1101of the seal disposing portion1096, and to bend under a lower surface1102of the seal disposing portion106. A surface of the felt seal member1093facing the roller1056of the developing roller1039forms a rubbing surface that rubs against the roller1056. With this arrangement, the side seal1091is adjacent to the cutout1060b.

(<Configuration of Toner Stirring Mechanism)

Next, the toner stirring mechanism1104will be described with reference toFIGS. 20,23, and24.FIG. 24is an enlarged perspective view of a vicinity of the toner stirring mechanism in the toner case of the developing cartridge, on which the developing roller and the supply roller are not mounted, as viewed from the opening.FIG. 24shows the toner case1036in a state where the blade unit1040, the paper feed roller1038, and the developing roller1039are removed.

The toner stirring mechanism1104has a connection gear1105serving as a connection member, a toner stirring gear1106serving as a rotary member, and a shaft1107.

The connection gear1105is provided to be inserted into the roller shaft1053of the supply roller1038. The connection gear1105transfers a driving force when the supply roller1038is driven to be rotated by a driving motor (not shown), to the toner stirring gear1106. Since the connection gear1105is inserted into the roller shaft1053of the supply roller1038, as indicated by an arrow inFIG. 20, the connection gear1105rotates in a counterclockwise direction.

The toner stirring gear1106is connected to the connection gear1105and is positioned in front of the cutout1060band below a vicinity of the front side of the cutout1049aof the blade support plate1049. The toner stirring gear1106receives the driving force when the connection gear1105rotates together with the roller shaft1053of the supply roller1038and rotates in a clockwise direction, as indicated by an arrow inFIG. 20. With the rotation of the toner stirring gear1106, the toner scraped from the surface of the roller1056of the developing roller1039by the cutout1060bpasses between the cutout1049aof the blade support plate1049and the toner stirring gear1106and returns to the toner containing chamber1037.

Both longitudinal ends of the shaft1107are rotatably supported by shaft receiving holes (not shown) that are formed in the support plate1095. The toner stirring gear1106is inserted into and fixed to the shaft1107. Moreover, in the blade support plate1049, the toner stirring gear1106that is inserted into and fixed to the shaft1107is disposed below one cutout1049athat is not shown inFIGS. 20 and 24.

The shaft1107is parallel to the roller shaft1053of the supply roller1038or the roller shaft1055of the developing roller1039, is inserted into the two toner stirring gears1106that rotate by driving force transferred from the connection gear1105and supports them, thereby achieving stable rotation of the toner stirring gear1106. In addition, since the shaft1010is connected to and drags the two toner stirring gears1106, two connection gears1105that are connected to the two toner stirring gears1106, respectively, do not need to be provided and a driving force does not needs to be transferred, but only one connection gear1105is sufficient. Therefore, the number of parts can be reduced, and thus costs can be reduced.

When the toner stirring mechanism1104is provided in the toner case1036of the developing cartridge1026, by using the driving force of the supply roller1038, the toner retained in the toner case1036in the vicinity of the cutout1060bcan be stirred and return to the toner containing chamber1037again. Therefore, it is possible to prevent the toner scraped from the developing roller1039by the cutout1060bfrom being accumulated on the back side as viewed from the opening1041of the cutout1060band then to prevent occurrence of a toner aggregate. Therefore, it is possible to prevent the toner aggregate from pressing the side seal1091adjacent to the cutout1060band entering a gap between the side seal1091and the seal disposing portion1096and then to prevent toner leakage.

The process cartridge1018includes the developing cartridge1026that can prevent toner leakage from a gap in the vicinity of the side seal1091, and thus it is possible to prevent toner leakage from the developing cartridge1026. In addition, in the laser printer including the process cartridge1018, it is possible to prevent toner leakage from the developing cartridge1026or the process cartridge1018.

The fixing unit19is provided on the rear side of the process cartridge18. The fixing unit19has a fixing frame67, and a heating roller68and a pressing roller69in the fixing frame67. The heating roller68has a metal tube and a halogen lamp provided in the metal tube for heating. The heating roller68is driven to be rotated by an input of power from a motor (not shown). The pressing roller69is disposed below the heating roller68to face and press the heating roller68. The pressing roller69is formed by coating a metal roller shaft with a roller formed of a rubber material and is driven according to the rotation of the heating roller68.

MODIFICATION

Although the invention has been described by way of the embodiment, the invention is not limited to the embodiment. Various changes and modifications can be made within the scope without departing from the technical scope of the invention.

Although the driving force of the supply roller1038is transferred to the toner stirring gear1106by the connection gear1105in the embodiment, instead of the connection gear1105, a separate driving motor from the motor that rotates the supply roller1038may be provided, and the shaft1107may be directly rotated by the driving motor so as to drag the toner stirring gear1106.

As described above, when the separate driving motor is provided, the shape of the toner stirring gear1106may be not a gear. Any shape can be used as long as it can stir the toner in the toner case36in the vicinity of the cutout1060b.