Developer transportation device and image forming apparatus

A developer transportation device includes a storage portion for storing developer; a transportation member formed of an elastic material and disposed in the storage portion to be freely rotatable for transporting the developer upon rotating; and a rotation transmission member for transmitting a rotation to the transportation member. The transportation member may be provided with an abutting portion abutting against a wall portion of the storage portion when the transportation member rotates.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a developer transportation device for supplying a sheet and an image forming apparatus having the developer transportation device.

In a conventional image forming apparatus such as a printer, a copier, a facsimile, and the likes, a charge roller charges a surface of a photosensitive drum, and an LED (Light Emitting Diode) head exposes the surface of the photosensitive drum to form a static latent image thereon. Then, a developing roller attaches a thin layer of toner to the static latent image through static electricity, thereby forming a toner image. A transfer roller transfers the toner image to a sheet, and a fixing device fixes the toner image to the sheet, thereby forming an image on the sheet. After the transfer roller transfers the toner image to the sheet, a cleaning blade scrapes off toner remaining on the photosensitive drum, so that toner is collected as waste toner.

When the cleaning blade collects waste toner, a toner transportation device as a developer transportation device transports waste toner to a waste toner box, so that waste toner can be discarded externally. The toner transportation device includes a transportation spiral as a transportation member having a coil shape. When the transportation spiral rotates, the transportation spiral transports waste toner (refer to Patent Reference).Patent Reference: Japan Patent Publication No. 2006-58729

SUMMARY OF THE INVENTION

According to the present invention, a developer transportation device includes a storage portion for storing developer; a transportation member formed of an elastic material and disposed in the storage portion to be freely rotatable for transporting the developer upon rotating; and a rotation transmission member for transmitting a rotation to the transportation member.

According to the present invention, the transportation member may be provided with an abutting portion abutting against a wall portion of the storage portion when the transportation member rotates.

In the present invention, the developer transportation device includes the storage portion for storing the developer; the transportation member formed of the elastic material and disposed in the storage portion to be freely rotatable for transporting the developer upon rotating; and the rotation transmission member for transmitting the rotation to the transportation member. The transportation member may be provided with the abutting portion abutting against the wall portion of the storage portion when the transportation member rotates.

In the present invention, when the transportation member rotates, the abutting portion abuts against the wall portion of the storage portion, thereby generating a vibration. Accordingly, when the developer becomes an agglomerate on the wall portion of the storage portion, it is possible to brake up and scrape off the agglomerate. As a result, it is possible to prevent the transportation member from being damaged due to the agglomerate, thereby extending lifetime of the developer transportation device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereunder, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a printer will be explained as an image forming apparatus.

First Embodiment

A first embodiment of the present invention will be explained.FIG. 2is a schematic side view showing a printer according to the first embodiment of the present invention.

As shown inFIG. 2, the printer includes image forming units (ID units)10Bk,10Y,10M, and10C for forming toner images as developer images in black, yellow, magenta, and cyan, respectively, according to image data. The printer also includes a transfer unit u1of a belt type disposed to face the image forming units10Bk,10Y,10M, and10C, so that transfer areas in each color are formed between the transfer unit u1and the image forming units10Bk,10Y,10M, and10C for transferring the toner images in each color to a sheet P as a medium.

In the embodiment, the printer further includes a sheet supply cassette (not shown) as a medium storage portion for supplying the sheet P to each of the transfer areas and a fixing unit21as a fixing device for fixing the color toner images to the sheet P after the toner images are transferred to the sheet P in the transfer areas.

In the embodiment, the transfer unit u1includes a drive roller (not shown) as a first roller connected to a motor (not shown) as a transfer drive portion for rotating upon receiving a rotation of the motor; an idle roller (not shown) as a second roller for rotating while following the rotation of the drive roller; an endless belt81as a transfer belt or a belt placed between the drive roller and the idle roller; transfer rollers19disposed inside the endless belt81to face photosensitive drums11as static latent image supporting members of the image forming units10Bk,10Y,10M, and10C, and to be freely movable; and a first cleaning device82disposed near the idle roller for abutting against an outer circumferential surface of the endless belt81. The idle roller is arranged to apply tension to the endless belt81, and alternatively a tension roller may be disposed.

In the embodiment, the image forming units10Bk,10Y,10M, and10C have an identical configuration. Each of the image forming units10Bk,10Y,10M, and10C includes the photosensitive drum11arranged to be freely rotatable. Further, each of the image forming units10Bk,10Y,10M, and10C includes a charge roller12as a charging device, a developing roller14as a first developer image supporting member, and a second cleaning device83arranged in this order along a rotational direction of the photosensitive drum11. An LED (Light Emitting Diode) head13as an exposure device is disposed between the charge roller12and the developing roller14to face the photosensitive drum11for exposing a surface of the photosensitive drum11, thereby forming a static latent image as a latent image thereon.

In the embodiment, the charge roller12is formed of a conductive shaft made of stainless steel and the likes, and the conductive shaft is covered with a conductive elastic member made of an epichlorohydrin rubber and the likes. The charge roller12is arranged to contact with the photosensitive drum11. The LED head13is formed of an LED element and a lens array. When the LED element emits light, the lens array collects light and forms an image on the surface of the photosensitive drum11.

In the embodiment, the developing roller14is formed of a conductive shaft made of stainless steel and the likes, and the conductive shaft is covered with a conductive elastic member made of a urethane rubber and the likes. A surface of the developing roller14is polished to have an appropriate roughness, and may be coated if necessary. The developing roller14is arranged to contact with the photosensitive drum11.

In the embodiment, a toner supply roller15as a developer supply member and a developing blade17as a developer regulating member are disposed around the developing roller14. The toner supply roller15is formed of a conductive shaft made of stainless steel and the likes, and the conductive shaft is covered with a foam elastic member made of a silicone rubber and the likes.

In the embodiment, the developing blade17is formed of a metal plate made of stainless steel. A distal end portion of the metal plate is bent at a specific curvature to form a curved portion. The curved portion is polished and pressed against the developing roller14for regulating a layer thickness of toner as developer supplied from the toner supply roller15to the developing roller14.

In the embodiment, the transfer roller19is formed of a conductive shaft made of stainless steel and the likes, and the conductive shaft is covered with a foam elastic member made of a silicone rubber and the likes. The transfer rollers19are arranged to press against the photosensitive drums11with the endless belt81in between.

In the embodiment, the first cleaning device82includes a cleaning blade84as a first cleaning member, so that the cleaning blade84scrapes off toner attached to the endless belt81. In this case, the endless belt81constitutes a second developer supporting member.

In the embodiment, the first cleaning device82is attached to each of the image forming units10Bk,10Y,10M, and10C. The second cleaning device83includes a waste toner storage portion29as a first storage portion or a first developer waste transportation path extending in an axial direction along the photosensitive drum11; a cleaning blade20as a second cleaning member attached to a wall portion87of the waste toner storage portion29at a specific position thereof; and a transportation spiral23as a first transportation member disposed in the waste toner storage portion29below the cleaning blade20to be freely rotatable. The cleaning blade20is provided for scraping off toner remaining on the photosensitive drum11. Note that the photosensitive drum11constitutes a third developer supporting member.

In the embodiment, the cleaning blade20is formed of a metal plate having a curved shape, and a urethane rubber with a rectangular shape is attached to the metal plate. Further, the cleaning blade20is arranged such that a distal end portion of the urethane rubber is pressed against the photosensitive drum11with a specific linear pressure.

In the embodiment, the waste toner storage portion29is integrally formed with a housing body cs, and may be formed separately from the housing body cs. The transportation spiral23is formed of a wire made of an elastic material such as stainless steel, and the wire is formed in a specific shape.

In the embodiment, a toner cartridge86as a developer cartridge is disposed above the developing roller14for storing toner. The toner cartridge86is detachably attached to a main body of each of the image forming units10Bk,10Y,10M, and10C or an image forming unit main body. A waste toner tank24as a developer waste storage container is disposed inside a main body of the toner cartridge86or a container main body for storing waste toner or developer waste scraped off with the cleaning blade20.

In the embodiment, a waste toner collection route25as a second storage portion or a second developer waste transportation path connects the second cleaning device83and the waste toner tank24. Note that the second cleaning device83and the waste toner collection route25constitute a waste toner transportation unit as a developer waste transportation unit.

An operation of the printer will be explained next. First, in each of the image forming units10Bk,10Y,10M, and10C, a charge voltage is applied to the charge roller12, so that the charge roller12uniformly charges the surface of the photosensitive drum11. Then, image data are sent to the LED head13, so that the LED head13exposes the surface of the photosensitive drum11, thereby forming the static latent image thereon.

When toner is supplied from the toner cartridge86to the image forming unit main body, the toner supply roller15supplies toner to the developing roller14. Then, the developing blade17forms a thin layer of toner on the developing roller14, so that toner is attached to the photosensitive drum11, thereby developing the static latent image to form the toner image in each color.

In the next step, a transfer voltage is applied to the transfer roller19, so that the toner image on the photosensitive drum11is sequentially overlapped and transferred to the sheet P, thereby forming a color toner image. The, the sheet P is transported to the fixing unit21, so that the color toner image is fixed to the sheet P in the fixing unit21, thereby forming a color image. Through the operation described above, a printing operation is performed.

After the toner image in each color is transferred to the sheet P, the cleaning blade20scrapes off toner remaining on the photosensitive drum11. After the cleaning blade20scrapes off toner, toner is collected in the waste toner storage portion29as waste toner. Then, the transportation spiral23disposed in the waste toner storage portion29transports waste toner to the waste toner collection route25, so that waste toner is stored therein. After waste toner is stored in the waste toner collection route25, waste toner is transported from the waste toner collection route25to the waste toner tank24.

When the printing operation is repeated, and waste toner is gradually agglomerated and forms an agglomerate in the waste toner storage portion29, the agglomerate may stick to an inner wall portion of the wall portion87. Accordingly, it is difficult to collect waste toner scraped off with the cleaning blade20any more, thereby causing cleaning malfunction.

Further, waste toner tends to agglomerate on a downstream side of the waste toner storage portion29, i.e., a portion near the waste toner collection route25. When waste toner is accumulated on the agglomerate, a large load is applied to the transportation spiral23. In an extreme case, the transportation spiral23may be damaged.

To this end, in the embodiment, it is configured such that it is possible to prevent waste toner from agglomerating in the waste toner collection route25.

The waste toner transportation unit will be explained in more detail next.FIG. 1is a schematic view showing the waste toner transportation unit according to the first embodiment of the present invention.FIG. 3is a schematic view showing a waste toner receiving portion according to the first embodiment of the present invention.

As shown inFIG. 1, the waste toner transportation unit includes the second cleaning device83, the cleaning blade20, and the transportation spiral23. The transportation spiral23includes a main body portion23aand a discharge portion23b. The main body portion23ais formed of a stainless steel wire with a circular cross section formed in a coil shape. The discharge portion23bis formed at a specific position, i.e., one end portion, of the main body portion23aas a free end portion, and is formed of a wire having a U character shape.

In the embodiment, a drive gear26as a rotation transmission member is attached to the other end portion of the main body portion23afor transmitting a rotation to the transportation spiral23. The drive gear26is connected to a discharge motor (not shown) as a discharge drive unit for discharging waste toner30to the waste toner collection route25. Note that the waste toner collection route25, the transportation spiral23, and the cleaning blade20constitute a developer transportation device.

In the embodiment, the main body portion23ahas a rotational shaft sh1, and the discharge portion23bhas a rotational shaft sh2. As shown inFIG. 3, the rotational shaft sh2is shifted relative to the rotational shaft sh1, so that a rotational path28of the discharge portion23bpartially interferes with the wall portion87. In this case, the discharge portion23bconstitutes an abutting portion, and the wall portion87constitutes an abutted portion.

In the embodiment, a transportation belt27as a second transportation member is disposed in the waste toner collection route25. A transportation motor (not shown) as a transportation drive unit drives the transportation belt27to move.

In the embodiment, the waste toner receiving portion is formed at a connecting portion between the waste toner collection route25and one end portion of the waste toner storage portion29. The discharge portion23bis situated adjacent to the transportation belt27at the waste toner receiving portion. The transportation belt27is formed of a flexible plastic, and includes a belt main body27aformed in a band shape and a plurality of teeth portion27bas a transportation section protruding outwardly from the belt main body27awith an equal interval in between. Note that the discharge portion23bis arranged to face the waste toner collection route25and the transportation belt27.

An operation of the waste toner transportation unit will be explained.FIG. 4is a schematic view No.1showing the operation of the waste toner transportation unit according to the first embodiment of the present invention.FIG. 5is a schematic view No.2showing the operation of the waste toner transportation unit according to the first embodiment of the present invention.

FIG. 6is a schematic view No.3showing the operation of the waste toner transportation unit according to the first embodiment of the present invention.FIG. 7is a schematic view No.4showing the operation of the waste toner transportation unit according to the first embodiment of the present invention. When the transportation spiral23rotates, the operation shown inFIGS. 4 to 7is repeated in this order.

When the transportation motor drives, a rotation of the transportation motor is transmitted to the drive gear26, so that the transportation spiral23rotates around the rotation shaft sh1in the waste toner storage portion29. As described above, the cleaning blade20scrapes off the waste toner30from the photosensitive drum11, and the waste toner30is collected in the cleaning blade20. Accordingly, the coil portion of the main body portion23apushes the waste toner30toward the waste toner collection route25to the connecting portion, so that the discharge portion23btransports the waste toner30from the transportation spiral23to the transportation belt27at the connecting portion. Then, the transportation belt27moves to transport the waste toner30further to the waste toner tank24.

In the embodiment, as described above, the discharge portion23bis shifted relative to the main body portion23a. When the transportation spiral23rotates, the rotational path28of the discharge portion23bpartially interferes with the wall portion87, so that the discharge portion23brepeatedly abuts against the wall portion87.

As a result, as shown inFIG. 6, the main body portion23ais deformed periodically, and the rotational shaft sh1is deformed locally. When the discharge portion23bdoes not abut against the wall portion87, the main body portion23areturns to an original shape thereof. Accordingly, as shown inFIG. 7, the rotational shaft sh1returns to an original shape thereof.

As described above, the transportation spiral23is formed of the wire formed in the coil shape, and has elasticity. Accordingly, when the main body portion23ais deformed periodically, the transportation spiral23vibrates as a whole. With the vibration, it is possible to crash and scrape off the agglomerate33of the waste toner30formed on the inner wall portion of the wall portion87.

As described above, in the embodiment, every time the transportation spiral23rotates, the vibration is generated. Accordingly, it is possible to prevent the waste toner30from agglomerating and the agglomerate33from being formed. The main body portion23ais formed in the coil shape. Accordingly, the transportation spiral23vibrates along an irregular path, so that is it possible to crash the agglomerate33of the waste toner30over a large area. It is possible to prevent the waste toner30from accumulating in the waste toner storage portion29, thereby preventing the transportation spiral23from being damaged, and increasing a lifetime of the toner transportation device as the developer transportation device.

In the embodiment, the discharge portion23bis formed at the one end portion of the transportation spiral23, and the discharge portion23bconstitutes the abutting portion. Alternatively, other portion of the transportation spiral23may constitute the abutting portion.

Second Embodiment

A second embodiment of the present invention will be explained next. Components in the second embodiment similar to those in the first embodiment are designated with the same reference numerals, and explanations thereof are omitted. The components in the second embodiment similar to those in the first embodiment provide similar effects.

FIG. 8is a schematic sectional view showing a cleaning device according to the second embodiment of the present invention.

In the embodiment, a transportation spiral31includes a main body portion31aand a discharge portion31bhaving a U character shape. The main body portion31ais formed in a coil shape having an oval cross section. A wire made of stainless steel is wound around a metal shaft having an oval cross section to form the main body portion31a.

An operation of the transportation spiral31will be explained next. As described above, the main body portion31ahas the coil shape having the oval cross section. Accordingly, when the transportation spiral31rotates, the transportation spiral31itself moves and vibrates in a vertical direction and a lateral direction. As a result, it is possible to prevent the waste toner30from agglomerating and the agglomerate33from being formed. Even when the agglomerate33of the waste toner30is formed on the inner wall portion of the wall portion87, the transportation spiral31vibrates to crash and scrape off the agglomerate33.

As described above, the main body portion31ahas the coil shape having the oval cross section. Accordingly, a portion of the transportation spiral31having a larger diameter contacts with the wall portion87. That is, the transportation spiral31contacts with the wall portion87all the time. Accordingly, it is possible to increase an amount of toner to be transported and prevent noise due to an impact.

Third Embodiment

A third embodiment of the present invention will be explained next. Components in the third embodiment similar to those in the first and second embodiments are designated with the same reference numerals, and explanations thereof are omitted. The components in the third embodiment similar to those in the first and second embodiments provide similar effects.

In the first embodiment, the transportation spiral23is formed of the wire having the circular cross section. Accordingly, when the waste toner30agglomerates, the agglomerate33tends to be formed through a mechanism described below.

FIG. 9is an enlarged schematic sectional view No1showing a mechanism of forming the agglomerate33.FIG. 10is an enlarged schematic sectional view No2showing the mechanism of forming the agglomerate33.

As shown inFIGS. 9 and 10, the transportation spiral23is formed of a wire34. When the transportation spiral23rotates, the waste toner30is transported in an arrow direction A. As the wire34has a circular cross section, the waste toner30situated near the transportation spiral23receives a force in an arrow direction B and is pushed outwardly in a radial direction. Accordingly, the waste toner30tends to agglomerate on the inner wall portion of the wall portion87, thereby forming the agglomerate33. When the transportation spiral23rotates at a higher rotational speed, the transportation spiral23pushes the waste toner30outwardly in the radial direction with a larger force, thereby further forming the agglomerate33.

In the third embodiment, it is possible to prevent the agglomerate33from being formed more efficiently.FIG. 11is a schematic view showing a waste toner transportation unit according to a third embodiment of the present invention.FIG. 12is a schematic view No.1showing an operation of a transportation spiral36according to the third embodiment of the present invention.FIG. 13is a schematic view No.2showing the operation of the transportation spiral36according to the third embodiment of the present invention.

In the embodiment, the transportation spiral36is formed of a wire37, and the wire37has a triangular shape section having three top portions, that is, the wire37is formed of an irregular section wire. The transportation spiral36includes a main body portion36aand a discharge portion36b. The wire37has one surface sa situated at an outer circumferential edge of the main body portion36a.

When the transportation spiral36rotates, the waste toner30is transported in an arrow direction A. Since the wire37has the triangular shape section, the waste toner30situated near the transportation spiral36receives a force in an arrow direction C, so that the waste toner30is pushed inwardly in a radial direction of the transportation spiral36. Accordingly, it is possible to prevent the waste toner30from agglomerating, and the agglomerate33from being formed on the inner wall portion of the wall portion87.

In the embodiment, even when the agglomerate33is formed, the agglomerate33is not pushed outwardly in the radial direction of the transportation spiral36. Accordingly, when the transportation spiral36rotates, it is possible to easily crash and scrape off the agglomerate33of the waste toner30formed on the inner wall portion of the wall portion87.

In the embodiment, the discharge portion36binterferes with the wall portion87, so that the transportation spiral36vibrates. Accordingly, it is possible to easily scrape off the agglomerate33of the waste toner30formed on the inner wall portion of the wall portion87with a corner of the wire37. Note that the features in the third embodiment may be applied to the features in the second embodiment.

Fourth Embodiment

A fourth embodiment of the present invention will be explained next. Components in the fourth embodiment similar to those in the first to third embodiments are designated with the same reference numerals, and explanations thereof are omitted. The components in the fourth embodiment similar to those in the first to third embodiments provide similar effects.

FIG. 14is a schematic view No.1showing an operation of a transportation spiral38according to the fourth embodiment of the present invention.FIG. 15is a schematic view No.2showing the operation of the transportation spiral38according to the fourth embodiment of the present invention.

In the embodiment, the transportation spiral38is formed of a wire39, and the wire39has a rectangular shape section having four corner portions, that is, the wire39is formed of an irregular section wire. The transportation spiral38includes a main body portion38aand a discharge portion (not shown). The wire39has one surface sa situated at an outer circumferential edge of the main body portion38a.

When the transportation spiral38rotates, the waste toner30is transported in an arrow direction A. Since the wire39has the rectangular shape section, the waste toner30situated near the transportation spiral38receives a force in an arrow direction D, so that the waste toner30is pushed in an axial direction of the transportation spiral36. Accordingly, it is possible to prevent the waste toner30from agglomerating, and the agglomerate33from being formed on the inner wall portion of the wall portion87.

In the embodiment, it is possible to transport a large amount of the waste toner30with a large transportation force with the transportation spiral38. Accordingly, even when the agglomerate33is formed, only a small amount of the waste toner30reaches an inner circumferential surface of the wall portion87, thereby making it easy to crash the agglomerate33. Further, since the wire39has the rectangular shape section with the corners, when the transportation spiral38rotates, it is possible to easily crash and scrape off the agglomerate33of the waste toner30formed on the inner wall portion of the wall portion87.

In the embodiment, the discharge portion interferes with the wall portion87, so that the transportation spiral38vibrates. Accordingly, it is possible to easily scrape off the agglomerate33of the waste toner30formed on the inner wall portion of the wall portion87with a corner of the wire39. Note that the features in the fourth embodiment may be applied to the features in the second embodiment.

In the embodiments described above, the present invention is applied to the printer as the image forming apparatus, and may be applicable to other device, for example, a copier, a facsimile, and a multifunction product.

In the embodiments described above, the present invention is applied to the second cleaning device83, and may be applicable to the first cleaning device82. Further, the present invention may be applicable to a portion through which toner is transported from one container to another container. Further, the features in the first embodiment may be combined with those in the third embodiment.

The disclosure of Japanese Patent Application No. 2007-251804, filed on Sep. 27, 2007, is incorporated in the application by reference.