Belt cleaning device having cleaning blade for image forming apparatus

A pressure release cam and a boomerang cam are provided. The pressure release cam is interlocked with a belt cleaner when the latter is turned, whereas the boomerang cam is interlocked with the belt cleaner when the latter is mounted in position. As the belt cleaner is turned to move the cleaning blade away from an intermediate transfer belt, the pressure release cam is moved to a release position to release the cleaning member from the pressure applied to it by a pushing unit. The pressure applied by the pushing unit to the cleaning member is restored when the boomerang cam is turned as a motion interlocked with the operation of mounting the belt cleaner in position and the pressure release cam is taken out from the release position. The cleaner frame is provided with first and second guide rails for allowing the belt cleaner to slide and a toner anti-fall dish.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2006-42772 filed on Feb. 20, 2006, No. 2006-42773 filed on Feb. 20, 2006 and No. 2006-42774 filed on Feb. 20, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an image forming apparatus such as an electronic photography type copying machine or printer for obtaining an image by means of an endless transfer belt that has a cleaning member for cleaning the surface of a transfer belt after a transfer operation.

2. Description of the Related Art

Tandem type image forming apparatus comprising a plurality of image forming units having respective photosensitive members and arranged in parallel and an endless intermediate transfer belt are known. In a tandem type image forming apparatus, the toner images formed on the respective photosensitive members are firstly transferred onto the endless intermediate transfer belt one on the other to form a single color toner image as primary transfer, which color image is then transferred onto a recording medium to produce a final color image as secondary transfer. Some tandem type image forming apparatus are equipped with a cleaning apparatus adapted to be brought into contact with the intermediate transfer belt and moved away from the latter. For example, Jpn. Pat. Publication (Kokai) No. 2001-255750 discloses such an apparatus.

In known such apparatus, a blade member is provided so as to be brought into contact with the intermediate transfer belt and moved away from the latter as an operation lever is turned. In recent years, there has been a demand for apparatus equipped with a removable cleaning apparatus that can be replaced independently relative to the intermediate transfer belt because the cleaning apparatus is in need of frequent maintenance. Such removable cleaning apparatus are required to be replaceable with ease without damaging the intermediate transfer belt.

Additionally, among tandem type image forming apparatus of the type under consideration, there are some in which the intermediate transfer belt cleaning apparatus is removably mounted in the apparatus main body. For example, Jpn. Pat. Publication (Kokai) No.2005-181820 and Jpn. Pat. Publication (Kokai) No. 2003-316107 discloses such apparatus.

In those known apparatus, the intermediate transfer member and the intermediate transfer member cleaning apparatus are integrally unitized so as to be integrally and removably mounted in the apparatus main body. Then, an anchor member that anchors the intermediate transfer member and the cleaning apparatus to the main body has to be released to take out the cleaning apparatus when performing maintenance on the cleaning apparatus that requires relatively frequent maintenance. Thus, the replacing operation requires much labor. Such apparatus are far from easy maintenance. Otherwise, the intermediate transfer belt has to be taken out from the apparatus main body when only the cleaning apparatus requires maintenance. Because the intermediate transfer belt is rather heavy, then the apparatus is also far from easy maintenance.

Therefore, it is desirable to replace a cleaning member for cleaning the belt member that is independent from the belt member in a safe and easy manner for a tandem type image forming apparatus comprising a plurality of image forming units, so as to prevent the surrounding units from being tainted by toner and improve the maintenance capability.

SUMMARY OF THE INVENTION

An aspect of the present invention is to provide a cleaning member for cleaning the belt member of an image forming apparatus that can be removably mounted in the image forming apparatus as a single unit in a condition where its cleaning blade is separated from the belt member. Thus, the cleaning member does not damage the belt member when the former is mounted in or taken out from the image forming apparatus so that the cleaning member can be safely replaced. Additionally, the cleaning member can be removably mounted in the image forming apparatus with ease and can prevent the surrounding units from being tainted by toner. Then, the maintenance capability of the cleaning member is improved.

According to an embodiment of the present invention, there is provided an image forming apparatus including: a plurality of image forming units having respectively toner image forming means for forming toner images on corresponding image carriers; an endless belt member arranged opposite to the image carriers to bear and move the toner images transferred from the image carriers as primary transfer and transfer them on a transfer medium; and a cleaning member arranged opposite to the belt member after transferring the toner image on the transfer medium and holding a cleaning blade so as to be able to bring the latter into contact and move it away from the belt member, the cleaning member being removably mounted in the image forming apparatus independently relative to the belt member; the cleaning member being adapted to be turned to move the cleaning blade away from the belt member and subsequently moved in a direction perpendicular to the running direction of the belt member so as to be removably mounted in the image forming apparatus independently relative to the belt member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, a preferred embodiment of the present invention will be described in greater detail by referring to the accompanying drawings.FIG. 1is a schematic perspective view of a 4-unit tandem type color copying machine1that is an image forming apparatus according to the embodiment of the present invention with its front cover1aopen, showing the appearance thereof.FIG. 2is a schematic illustration of an image forming section7of the color copying machine1, showing the configuration thereof. Referring toFIGS. 1 and 2, the color copying machine1comprises a scanner section2and an inter-body sheet ejecting section3. The color copying machine1also comprises four image forming units11Y,11M,11C and11K for four colors of yellow (Y), magenta (M), cyan (C) and black (K). The four image forming units11Y,11M,11C and11K are arranged in parallel relative to each other along and under an intermediate transfer belt10which is an endless belt member driven to turn in the direction of arrow s inFIG. 2.

The image forming units11Y,11M,11C and11K respectively include photosensitive drums12Y,12M,12C and12K that are image carriers. Electric chargers13Y,13M,13C and13K, development units14Y,14M,14C and14K, and photosensitive member cleaning apparatus16Y,16M,16C and16K are arranged respectively around the photosensitive drums12Y,12M,12C and12K in the direction of rotation thereof indicated by arrows m. The photosensitive drums12Y,12M,12C and12K are exposed respectively to laser beams emitted from a laser exposure apparatus17in zones from the electric chargers13Y,13M,13C and13K to the development units14Y,14M,14C and14K.

For example the electric chargers13Y,13M,13C,13K uniformly charge the entire surfaces of the respective photosensitive drums12Y,12M,12C,12K to about −700V. The development units14Y,14M,14C,14K supply the photoconductor drums12Y,12M,12C,12K with respective two component developers each comprising a toner (of yellow (Y), magenta (M), cyan (C), or black (K)) and a carrier.

The laser exposure apparatus17emits laser beams from its semiconductor laser element to scan the respective photosensitive drums12Y,12M,12C and12K in the axial directions of the photosensitive drums, focusing the laser beams on the photosensitive drums12Y,12M,12C and12K by way of respective focusing lens systems.

The intermediate transfer belt10is made of e.g., electrically semi-conductive polyimide that is a stable material from the viewpoint of thermal resistance and abrasion resistance. The intermediate transfer belt10is wound around a drive roller21, a follower roller20and first through fourth tension rollers22through25that are supported at the opposite ends thereof by a belt frame100as shown inFIG. 3. Primary transfer voltages are applied to the primary transfer position of the intermediate transfer belt10respectively at the positions located vis-à-vis the photosensitive drums12Y,12M,12C and12K by means of primary transfer rollers18Y,18M,18C and18K so that the toner images on the photosensitive drums12Y,12M,12C and12K are sequentially transferred onto the intermediate transfer belt10. The photosensitive member cleaning apparatus16Y,16M,16C and16K recover the residual toners on the photosensitive drums12Y,12M,12C and12K as waste toner after the primary transfer.

A secondary transfer roller27is arranged to face the intermediate transfer belt10at the position where the intermediate transfer belt10is supported by the drive roller21. A secondary transfer voltage is applied to the intermediate transfer belt10from the secondary transfer roller27at the secondary transfer position e.g., by way of a sheet of paper P that is a transfer medium supplied from a sheet feeding section4. Then, as a result, the toner image on the intermediate transfer belt10is transferred onto the sheet of paper P for secondary transfer. A belt cleaner10a, which is a cleaning member, is arranged opposite to the intermediate transfer belt10at a position downstream relative to the secondary transfer roller27so as to be brought into contact with and moved away from the intermediate transfer belt10. The belt cleaner10arecovers the toner remaining on the intermediate transfer belt10after the secondary transfer as waster toner.

The waste toner recovered by the photosensitive member cleaning apparatus16Y,16M,16C and16K and the belt cleaner10ais contained in a waste toner box30. The waste toner box30extends in an elongated manner on the front side of the image forming section7of the color copying machine1. When the waste toner box30is full, it is replaced with the new one.

As shown inFIG. 4, the belt cleaner10aincludes a cleaning blade50and a recovery blade50a. The cleaning blade50is held in sliding contact with the intermediate transfer belt10to recover the residual toner on the intermediate transfer belt10. The recovery blade50aprevents flying toner from leaking out from the belt cleaner10awhen recovering the residual toner. The waste toner recovered by the cleaning blade50is then conveyed to the front side by means of an auger51. The waste toner conveyed to the front side is made to fall and flow into the waste toner box30by way of a duct32.

The belt cleaner10acan be arranged selectively at the toner recovery position shown inFIG. 5and at the mounting/dismounting position shown inFIG. 6by operating lever70and turning it around bosses71. At the toner recovery position, the cleaning blade50is held in contact with the intermediate transfer belt10so that it can recover residual toner. At the mounting/dismounting position, the cleaning blade50is moved away from the intermediate transfer belt10. The bosses71are supported by respective boss carriers101that are fitted to the opposite sides of the belt frame100as shown inFIG. 8and position the belt cleaner10arelative to the intermediate transfer belt10.

Additionally, a first projection70aand a second projection70bare formed at the front side of the belt cleaner10a. The first projection70atriggers releasing the lock mechanism103, which will be described later. The second projection70bprevents the belt cleaner10afrom being drawn out when placed at the toner recovery position.

A cleaner frame72is arranged below the belt cleaner10a. The cleaner frame72is a support member for slidably supporting the belt cleaner10aarranged at the mounting/dismounting position as shown inFIGS. 5 and 6. The cleaner frame72is supported by the main body frame1cof the color copying machine1. The cleaner frame72has a first guide rail72aand a second guide rail72bas guide members.

The first guide rail72ais adapted to receive and engage with guide projections73that are receiving members formed respectively at the front side and the rear side of the belt cleaner10aas viewed in the longitudinal direction thereof. The guide projections73are held by the first guide rail72aso as to be able to slide as they are received by and engaged with the first guide rail72a. The first guide rail72ais provided with guide rail grooves75as a passage section formed by partly cutting out the guide rail72a. The guide rail grooves75are formed so as to allow the guide projections73to pass through them when the belt cleaner10ais turned so as to be brought into contact and moved away from the intermediate transfer belt10. The second guide rail72bholds the bottom surface74of the belt cleaner10a, allowing the bottom surface74to slide thereon.

The cleaner frame72additionally has a toner anti-fall dish72cas a toner receiving section. The toner anti-fall dish72cextends toward the contact region where the intermediate transfer belt10and the cleaning blade50contact with each other. The toner anti-fall dish72is adapted to receive the toner that falls near the cleaning blade50when the cleaning blade50is brought into contact and moved away from the intermediate transfer belt10, when the belt cleaner10ais slid, when the intermediate transfer belt10is taken out and etc.

The belt cleaner10ais held to the toner recovery position in the main body frame1cby the elastic force of the pushing units102as a pushing member fitted to the opposite lateral sides of the belt frame100. As shown inFIG. 11, the pushing units102respectively include hook members102athat are held in contact with the case rear surface10bof the belt cleaner10aand hook springs102bthat are elastic members fitted to the hook members102aso as to pull the latter in the direction indicated by arrow f.

The pushing units102are adapted to release the belt cleaner10aby means of the lock mechanism103that operates as a release member from the pressure applied to the belt cleaner10a. The lock mechanism103includes a lock shaft103asupported by the belt frame100and pressure release cams103bfitted respectively to the opposite sides of the lock shaft103a. A boomerang cam103cthat is a restoration member, or a restoration cam, is fitted to the front end of the lock shaft103a.

Each of the pressure release cams103bis put in a slit102cformed at the top surface of the corresponding hook member102aand has a substantially flat front end section105. When the belt cleaner10ais held to the toner recovery position, each of the pressure release cams103bis held stationary with its front end section105located at a high position as shown inFIGS. 12 and 13. Therefore, the hook members102aare not restricted by the pressure release cams103band pulled in the direction of arrow f by the elastic force of the hook springs102b.

When the belt cleaner10ais held to the mounting/dismounting position, each of the pressure release cams103bis held stationary at the respective release position where the front end section105thereof contacts the planar region106at the front end of the slit102cformed at the top surface of the hook member102aas shown inFIGS. 14 and 15. Therefore, the hook member102ais pushed in the direction of arrow j with the corresponding pressure release cam103bto release the belt cleaner10afrom the pressure applied to it.

The boomerang cam103cis a cam for triggering a clockwise turn of the corresponding pressure release cam103b, which is in the state shown inFIG. 15, in the direction of arrow h inFIG. 11. As the second projection70bof the belt cleaner10acontacts the first end section104aof the boomerang cam103c, the boomerang cam103cis forced to turn in the direction of arrow h to turn the corresponding pressure release cam103bin the direction of arrow h via the lock shaft103a. Then, as a result, the pressure release cam103bis taken out from the release position.

Now, the operation of the above-arrangement will be described below. When an image forming process is started, the belt cleaner10ais at the toner recovery position as shown inFIG. 5and the cleaning blade50contacts the intermediate transfer belt10to recover the residual toner on the intermediate transfer belt10.

As the image forming process is started in this condition, image information is input from a scanner, a personal computer terminal or the like and the photosensitive drums12Y,12M,12C and12K are driven to rotate so that the image forming steps are sequentially brought into effect in the image forming units11Y,11M,11C and11K. In the yellow (Y) image forming unit11Y, the surface of the photosensitive drum12Y is uniformly charged with electricity by the electric charger13Y.

Subsequently, an electrostatic latent image is formed on the photosensitive drum12Y as the photosensitive drum12Y is irradiated with a laser beam that corresponds to the image information for yellow (Y) at the exposure position17Y. Thereafter, a toner image is formed on the photosensitive drum12Y by the development units14Y. Then, the photosensitive drum12Y contacts the intermediate transfer belt10that is being turned in the direction of arrow s to transfer the toner image onto the intermediate transfer belt10for primary transfer by means of the primary transfer roller18Y.

A toner image forming process is executed for each of the colors of magenta (M), cyan (C) and black (K) like the toner image forming process for yellow (Y). The toner images formed respectively on the photosensitive drums12M,12C and12K are sequentially transferred and laid on the yellow (Y) toner image one on the other on the intermediate transfer belt10. Thus, a full color toner image is formed on the intermediate transfer belt10as a result of multiply transferring the toner images of yellow (Y), magenta (M), cyan (C) and black (K).

The full color toner image formed by laying the monochromatic toner images one on the other gets to the position of the secondary transfer roller27. Then, the full color toner image on the intermediate transfer belt10is transferred onto a sheet of paper P in a batch due to the transfer bias voltage of the secondary transfer roller27. The toner image is finished when the sheet of paper P passes through the fixing step. After the fixing step, the sheet of paper P is discharged to the inter-body sheet ejecting section3when it is for single side printing. When, on the other hand, the sheet of paper P is for double side printing or multiplex printing, it is conveyed back to the position of the secondary transfer roller27by way of a re-conveyance unit (not shown).

Meanwhile, the intermediate transfer belt10is cleaned off the residual toner by the belt cleaner10aafter the end of the secondary transfer. On the other hand, the photosensitive drums12Y,12M,12C and12K are cleaned off the respective residual toners by the photosensitive member cleaning apparatus16Y,16M,16C and16K after transferring the respective toner images onto the intermediate transfer belt10for primary transfer to make them ready for the next image forming process.

The belt cleaner10aconveys the waste toner recovered from the intermediate transfer belt10by means of the cleaning blade50that is held in contact with the intermediate transfer belt10to the front side by means of the auger51. The waste toner that is conveyed to the front side is then flowed into the waste toner box30by way of the duct32for accumulation.

If there arises an occasion where a maintenance operation of replacing the belt cleaner10aor some other operation has to intervene while the image forming process is in progress, the used belt cleaner10ais taken out from and a new belt cleaner10ais mounted on the main body frame1cin a manner as described below.

(Operation of Taking Out Used Belt Cleaner10a)

Firstly, the front cover1ais opened and the duct32is taken out. Then, the lever70is turned in the direction of arrow i and then the belt cleaner10ais turned around the bosses71that operate as fulcrums. As a result, the used belt cleaner10ais moved away from the intermediate transfer belt10and placed at the mounting/dismounting position.

As the belt cleaner10ais turned in the direction of arrow i, the case rear surface10bpushes the hook members102ato slide the hook members102ain the direction of arrow j against the elastic force of the hook springs102b. As the hook members102aslide in the direction of arrow j, the pressure release cams103bare pushed by the rear ends of the slits102cto turn in the direction of arrow g shown inFIG. 11. Thereafter, the front end sections105of the pressure release cams103bget to the respective positions shown inFIG. 15and held standing stationary at the respective release positions where they contact the corresponding planar regions106in the respective slits102c. As a result the pressure being applied to the belt cleaner10aby the pushing units102is removed.

As the belt cleaner10ais turned from the toner recovering position to the mounting/dismounting position, the guide projections73of the belt cleaner10apass the respective guide rail grooves75and become so positioned as to be able to be engaged with the first guide rail72aof the cleaner frame72. On the other hand, the bottom surface74of the belt cleaner10ais received in the second guide rail72b.

In this condition, the used belt cleaner10ais driven to slide in the direction toward the front side of the main body frame10athat is a direction perpendicular to the running direction of the intermediate transfer belt10as indicated by arrow s and taken out from the main body frame10c. If toner spills out from the cleaning blade50at this time, it is received by the toner anti-fall dish72c. Therefore, the spilled toner does not taint the surrounding. While the belt cleaner10ais being taken out from the main body frame10c, the hook members102amaintain the situation where the belt cleaner10ais released from the pressure they apply to it due to the pressure release cams103b.

(Operation of Fitting New Belt Cleaner10a)

Then, a new belt cleaner10ais brought into engagement with the first guide rail72aand the second guide rail72band driven to slide in the direction of being mounted in the cleaner frame72. As the first projection70of the cleaner frame72gets to the position of the boomerang cam103c, it contacts the first end section104aand starts turning the lock shaft103ain the direction of arrow h with the first end section104a.

As the lock shaft103ais turned in the direction of arrow h, the front end sections105of the pressure release cams103bare taken out from the respective release positions where they contact the planar regions106in the inside of the corresponding slits102cof the respective hook members102a. The hook members102aare subjected to force directed in the direction of arrow f due to the elastic force of the hook springs102b. Therefore, as the front end sections105of the pressure release cams103bleave the respective planar regions106, the pressure release cams103bare subjected to force directed in the direction of arrow f by the corresponding slits102cof the respective hook members102aand turned gradually in the direction of arrow h.

As a result, the hook members102apush the case rear surface10bof the belt cleaner10ato turn the latter around the bosses71, which operate as fulcrums, in the direction of arrow k. When the first projection70gets to the position of the boomerang cam103c, the guide projections73of the belt cleaner10aget to the positions of the respective guide rail grooves75of the first guide rail72a. Therefore, as the belt cleaner10ais turned in the direction of arrow k, the guide projections73leave the first guide rail72aby way of the respective guide rail grooves75.

Additionally, due to the pressure in the direction of allow f being applied by the hook members102a, the cleaning blade50of the belt cleaner10acontacts the intermediate transfer belt10so as to be able to recover the residual toner on the intermediate transfer belt10and make the intermediate transfer belt10ready for the next image forming process. At this time, the second projection70bis at a position where it interferes with the main body frame11cso as to prevent the belt cleaner10afrom being drawn out from the main body frame while the cleaning blade50is held in contact with the intermediate transfer belt10.

The above-described embodiment has pressure release cams103bthat are interlocked with the belt cleaner10awhen the latter is turned and a boomerang cam103cthat is interlocked with a belt cleaner10awhen the latter is mounted. When the belt cleaner10ais replaced, the pressure release cams103bare held standing stationary at the respective release positions while the belt cleaner10ais turned. As a result, the pressure of the pushing units102that urges the belt cleaner10atoward the intermediate transfer belt is released. Thus, the belt cleaner10acan be mounted/dismounted without contacting and damaging the intermediate transfer belt10and without any interference of the pushing units102.

The boomerang cam103cstarts turning as it is interlocked with the belt cleaner10awhen the latter is being mounted so that the pressure release cams103bare taken out from the respective release positions and subsequently the belt cleaner10ais urged toward the intermediate transfer belt by the pushing units102.

Thus, when only the belt cleaner10ais mounted and dismounted independently without taking out the intermediate transfer belt10, the belt cleaner10adoes not contact the intermediate transfer belt10to damage the latter. Then, it is possible to replace only the belt cleaner10asafely and easily to consequently improve the maintenance capability of the color copying machine.

The guide rail grooves75are formed on the first guide rail72aof this embodiment to facilitate the operation of moving the belt cleaner10awhen the belt cleaner10ais brought into contact and moved away from the intermediate transfer belt10. Additionally, when the belt cleaner10ais moved away from the intermediate transfer belt10, the guide projections73of the belt cleaner10acan easily be brought into engagement with the first guide rail72a. Then, the belt cleaner10acan be easily mounted and dismounted by sliding the guide projections73along the first guide rail72a.

Thus, when only the belt cleaner10ais mounted and dismounted independently without taking out the intermediate transfer belt10, the belt cleaner10adoes not contact the intermediate transfer belt10to damage the latter. In other words, it is possible to replace only the belt cleaner10asafely and easily to consequently improve the maintenance capability of the color copying machine.

Additionally, with the above-described embodiment, it is possible to mount and dismount only the belt cleaner10aindependently without taking out the intermediate transfer belt10once the belt cleaner10ais moved away from the intermediate transfer belt10. Thus, it is possible to replace only the belt cleaner10aalone with ease to improve the maintenance capability. Furthermore, the cleaner frame72that has the first and second guide rails72a,72bfor guiding the belt cleaner10awhen it is mounted and dismounted is equipped with a toner anti-fall dish72c. Therefore, if toner falls from the vicinity of the cleaning blade50when only the belt cleaner10ais being replaced, it is received by the toner anti-fall dish72cto prevent the surrounding units from being tainted by the falling toner. Still additionally, since the toner anti-fall dish72cis formed integrally with the first and second guide rails72a,72bfor guiding the belt cleaner10awhen it is mounted and dismounted, some of the their parts as well as the fitting positions thereof can be commonly used to reduce the cost and size of the overall machine.

The present invention is by no means limited to the above-described embodiment, which may be modified and altered in various different ways without departing from the spirit and scope of the present invention. For example, the release members are not limited to those described above in terms of structure and other factors so long as they are interlocked with the cleaning member to become able to release the pressure applied by the pushing members. The restoration members are also not limited those described above in terms of structure and other factors so long as they are interlocked with the cleaning member when the latter is mounted to become able to restore the release members and also the pushing members to the respective toner recovering positions.