JP2007101716A - Belt unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a belt member to stably run to improve image quality. <P>SOLUTION: A belt unit includes a first roller, a second roller, the belt member, and a holding member holding the first and second rollers. The holding member has an extending part which is formed integrally with the holding member and is extended from the holding member to the vicinity of an inner peripheral surface of the belt member. Since the extending part is extended to the vicinity of the inner peripheral surface of the belt member, foreign matter cannot be caught between the first and second rollers and the belt member. Consequently, not only the reduction of a frictional force between the first and second rollers and the belt member can be prevented but also foreign matter is not melt-fixed to the first and second rollers. As a result, the belt member can be stably run. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a belt unit and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a printer, a copying machine, a facsimile machine, or a multifunction machine, for example, a printer, the surface of a photosensitive drum is charged by a charging roller and exposed by an LED head to be electrostatic latent images. After forming a toner image by electrostatically attaching toner as a developer thinned on the developing roller to the electrostatic latent image, and transferring the toner image onto a sheet by a transfer roller The image is fixed by a fixing device. Further, the toner remaining on the photosensitive drum after the transfer is scraped off by the cleaning blade.

  The photosensitive drum, charging roller, developing roller, cleaning blade, and the like are unitized to form an image forming unit (ID unit, developing device, etc.), and the image forming unit is divided into black, yellow, magenta, and cyan colors. In the color printer provided in the image forming apparatus, a transfer unit as a belt unit is disposed so as to face the photosensitive drum of each image forming unit.

  The transfer unit includes a drive roller, a tension roller, a transfer belt as a belt member stretched between the drive roller and the tension roller, and a transfer faced to each photosensitive drum via the transfer belt. A belt frame for supporting a roller, the driving roller, a tension roller, a transfer roller, and the like;

  A sheet is conveyed between the image forming unit and the transfer unit, and the color toner images formed by the image forming unit are sequentially transferred onto the sheet to form a color toner image.

  By the way, in the image forming unit, a toner accumulation portion for depositing the toner scraped off by the cleaning device is disposed. The toner accumulation portion is disposed at a gap between the toner accumulation portion and the photosensitive drum or at both ends of the cleaning device. The toner leaked from the sealed portion or the like may fall to the transfer unit, and in this case, the dropped toner enters the transfer unit from between the transfer belt and the belt frame, and enters the inner peripheral surface of the transfer belt. The toner adheres to the transfer roller or is charged to a potential having a polarity opposite to that of the toner.

  In addition, foreign matter such as toner and paper dust floating in the vicinity of the transfer unit in the printer device, that is, in the apparatus main body, enters the transfer unit from between the transfer belt and the belt frame and adheres to the transfer roller. It indirectly adheres to the inner peripheral surface of the transfer belt. When foreign matter enters between the drive roller and the transfer belt, the frictional force between the drive roller and the transfer belt is reduced.

Therefore, a cleaning blade is attached to the belt frame to scrape off toner adhering to the inner peripheral surface of the transfer belt (see, for example, Patent Document 1).
JP-A-9-258568

  However, in the conventional printer, the toner that cannot be scraped off by the cleaning blade and enters between the drive roller or the tension roller and the transfer belt is caused by friction between the transfer belt and the drive roller or the tension roller. Or it fuse | melts to a tension roller. In particular, the toner adhering to the downstream side of the cleaning blade in the running direction of the transfer belt directly enters between the transfer belt and the drive roller or the tension roller and is fused to the drive roller or the tension roller.

  As a result, the transfer belt cannot be moved stably, and a difference occurs between the peripheral speed of the photosensitive drum and the transfer speed of the transfer belt, and a transfer position shift occurs when the toner image is transferred. The image quality is degraded.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a belt unit and an image forming apparatus that can solve the problems of the conventional belt unit, can stably run a belt member, and improve image quality. To do.

  For this purpose, the belt unit of the present invention is arranged to face an image forming unit including an image carrier.

  The first roller, the second roller, a belt member stretched between the first and second rollers, and a holding member for holding the first and second rollers.

  The holding member includes an extending portion that is formed integrally with the holding member and that extends from the holding member toward the vicinity of the inner peripheral surface of the belt member.

  According to the present invention, the belt unit is arranged to face the image forming unit including the image carrier.

  The first roller, the second roller, a belt member stretched between the first and second rollers, and a holding member for holding the first and second rollers.

  The holding member includes an extending portion that is formed integrally with the holding member and that extends from the holding member toward the vicinity of the inner peripheral surface of the belt member.

  In this case, since the extending portion extends toward the vicinity of the inner peripheral surface of the belt member, foreign matter does not enter between the first and second rollers and the belt member. Therefore, it is possible not only to prevent the frictional force between the first and second rollers and the belt member from being reduced, but also to prevent foreign matters from being fused to the first and second rollers.

  As a result, the belt member can be moved stably, and the image quality can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

  FIG. 1 is a perspective view of a transfer unit according to the first embodiment of the present invention, FIG. 2 is a schematic view of a printer according to the first embodiment of the present invention, and FIG. 3 is a sectional view taken along line XX in FIG. .

  In the figure, black, yellow, magenta, and cyan image forming units 11Bk, 11Y, 11M, and 11C are arranged along the conveyance direction of a sheet as a recording medium, and the image forming units 11Bk, 11Y, 11M, and 11C are arranged. 1, toner images as developer images of the respective colors are formed on the photosensitive drum 13 as an image carrier. For this purpose, LED heads 15Bk, 15Y, 15M, and 15C as exposure devices are disposed above the image forming units 11Bk, 11Y, 11M, and 11C so as to face the respective photosensitive drums 13. The LED heads 15Bk, 15Y, 15M, and 15C form an electrostatic latent image by irradiating each photosensitive drum 13 with light corresponding to image information.

  Also, a transfer unit 28 as a belt unit is disposed below each of the image forming units 11Bk, 11Y, 11M, and 11C. The transfer unit 28 includes a belt frame 24 as a holding member, a drive roller 25 as a first roller and a tension roller 26 as a second roller, which are rotatably disposed on the belt frame 24, and the drive roller 25. 2 and the tension roller 26, the transfer belt 12 as a belt member stretched in the direction of the arrow shown in FIG. 2 and the photosensitive drums 13 via the transfer belt 12 so as to face each other. The transfer rollers 22Bk, 22Y, 22M, and 22C are provided as transfer members. The transfer rollers 22Bk, 22Y, 22M, and 22C are attached to the photosensitive drums 13 via the transfer belt 12 by a biasing member (not shown). It is urged toward and supported rotatably. The tension roller 26 is biased by a biasing member (not shown) so as to apply tension to the transfer belt 12, and the drive roller 25 is rotated by driving a driving unit (not shown) so that the transfer belt 12 runs. . The belt frame 24 holds rollers such as the transfer rollers 22Bk, 22Y, 22M, and 22C, the drive roller 25, and the tension roller 26. A drive roller 25 is disposed on the downstream side in the traveling direction of the transfer belt 12 and a tension roller 26 is disposed on the upstream side.

  Next, the image forming units 11Bk, 11Y, 11M, and 11C will be described. Since the image forming units 11Bk, 11Y, 11M, and 11C have the same structure, only the image forming unit 11C will be described.

  The image forming unit 11C includes a cylindrical photosensitive drum 13, a charging roller 14 as a charging device that uniformly and uniformly charges the surface of the photosensitive drum 13, and the electrostatic latent image as a developer. The developing roller 16 as a developer carrying member, the cleaning blade 17 as a cleaning device for scraping and removing the toner remaining on the surface of the photosensitive drum 13 after transfer, and the cleaning blade 17 A toner depositing portion 18 as a developer depositing portion that is disposed below and deposits the removed toner, a toner conveying member 19 as a developer conveying member that conveys the deposited toner, and the like are provided.

  As shown in FIG. 3, the cleaning blade 17 is sealed by sealing means 31 and 32 on the left and right. The toner accumulated in the toner accumulation unit 18 is conveyed by the toner conveyance member 19 and collected in a toner collection unit (not shown). The toner collection unit is provided with a sensor as a collection amount detection unit (not shown), and the sensor detects the amount of toner collected by the toner collection unit, that is, the toner collection amount. When the set value is exceeded, a message prompting the user to replace the toner collecting unit is displayed on a display unit (not shown).

  Next, the operation of the printer having the above configuration will be described.

  In the image forming units 11Bk, 11Y, 11M, and 11C, the surface of each photosensitive drum 13 is uniformly and uniformly charged by the charging roller 14, and then the LED heads 15Bk, 15Y, 15M, and 15C are The photosensitive drum 13 is exposed to form an electrostatic latent image of each color. The developing roller 16 develops the electrostatic latent image to form a toner image.

  On the other hand, as shown in FIG. 2, the paper supplied by the paper supply roller 20 as the medium supply member is aligned and conveyed in the conveyance direction by the registration roller 21, and conveyed in the arrow direction by the transfer belt 12. The toner images formed on the photoconductive drums 13 of the image forming units 11Bk, 11Y, 11M, and 11C are sequentially superimposed and transferred by the transfer rollers 22Bk, 22Y, 22M, and 22C to form a color toner image. Subsequently, the paper on which the color toner image is formed is sent to the fixing unit 23, and is fixed to the paper by applying pressure and heat. Thereafter, the paper is discharged out of the printer.

  Incidentally, the drive roller 25 is formed, for example, by covering the surface of a metal roller with a surface layer made of rubber or a coating layer containing ceramic powder so that a large frictional force is generated between the drive roller 25 and the transfer belt 12. When the drive roller 25 is rotated, the transfer belt 12 is caused to travel.

  Then, foreign matter such as toner, paper dust, etc. along the running direction of the transfer belt 12 between the shafts of the drive roller 25 and the tension roller 26 and in the vicinity of both ends in the width direction of the transfer belt 12. However, in order to prevent entry into the region formed by the transfer belt 12, that is, the transfer unit 28, the rib 27, which is an extended portion as a foreign matter entry preventing member, protrudes upward and is integrated. It is formed. The rib 27 is extended in the vicinity of the inner peripheral surface of the transfer belt 12 at a position corresponding to the end of the transfer belt 12 in the width direction. That is, the rib 27 allows a clearance of about 1 mm between the rib 27 and the transfer belt 12 so as to come into contact with the transfer belt 12. If the gap is larger than 1 [mm], foreign matter will enter, so the gap between the rib 27 and the transfer belt 12 is preferably 0 to 1 [mm]. Further, the belt frame 24 is disposed so as to slightly protrude from the horizontal plate-like portion 24a of the belt frame 24 between the transfer rollers 22Bk, 22Y, 22M, and 22C.

  The transfer belt 12 (FIG. 2) is moved in the direction of the arrow by the rotation of the drive roller 25, but the rib 27 always closes the gap between the belt frame 24 and the transfer belt 12. That is, even if foreign matter falls from between the photoconductive drum 13 and the sealing means 31 and 32 of the cleaning blade 17 in the image forming units 11Bk, 11Y, 11M, and 11C, and the photosensitive drum 13, Since entry can be prevented, foreign matter does not enter between the drive roller 25 or the tension roller 26 and the transfer belt 12. Therefore, not only the frictional force between the drive roller 25 or the tension roller 26 and the transfer belt 12 can be prevented, but also the toner is not fused to the drive roller 25 or the tension roller 26.

  As a result, the transfer belt 12 can be moved stably, a difference between the circumferential speed of the photosensitive drum 13 and the running speed of the transfer belt 12 can be prevented, and the toner image is transferred. In this case, the transfer position is not shifted. Therefore, the image quality can be improved.

  Further, since the rib 27 is formed integrally with the belt frame 24, the rib 27 can be easily formed, and the cost of the transfer unit 28 can be reduced. Since the ribs 27 are integrally formed on the belt frame 24, the ribs 27 are not detached from the belt frame 24 as time elapses. Further, since the rib 27 is formed integrally with the belt frame 24, the rib 27 can be opposed to the transfer belt 12 with high accuracy at the end portion in the width direction of the transfer belt 12.

  In the present embodiment, as shown in FIG. 3, the rib 27 is formed upward on the belt frame 24, but the rib can also be formed downward. In the present embodiment, the ribs 27 are formed at both ends of the transfer belt 12 in the width direction. However, the ribs 27 can be formed only on one side where foreign matter easily enters.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol, and the effect of the same embodiment is used about the effect of the invention by having the same structure. .

  FIG. 4 is a perspective view showing a main part of a transfer unit according to the second embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line AA of FIG.

  In this case, as in the first embodiment, the transfer belt 12 runs on the belt frame 24 between the shafts of the drive roller 25 and the tension roller 26 and in the vicinity of both ends in the width direction of the transfer belt 12. In order to prevent foreign matters such as toner and paper dust from entering the transfer unit 28 along the direction, the ribs 27 are integrally formed by projecting upward, and the distance between the transfer belt 12 and the ribs 27. δ is set to 0 to 1 [mm].

  The tension roller in the belt frame 24 prevents the toner from adhering to the transfer rollers 22Bk, 22Y, 22M, and 22C, the drive roller 25, or the tension roller 26 even if foreign matter enters the transfer unit 28. Five box-shaped foreign matter collecting portions 35 are formed between the transfer roller 26B and the transfer roller 22Bk, between the transfer rollers 22Bk, 22Y, 22M, and 22C, and between the transfer roller 22C and the drive roller 25.

  In the present embodiment, since the foreign matter collecting part 35 is formed, the foreign matter that has entered the transfer unit 28 is collected and accumulated on the bottom 35a of the foreign matter collecting part 35, but the inner peripheral surface of the transfer belt 12 Since a predetermined distance is placed between the bottom portion 35a and the bottom portion 35a, the foreign matter deposited on the bottom portion 35a does not contact and adhere to the inner peripheral surface. Therefore, the toner does not adhere to the inner peripheral surface of the transfer belt 12 and does not adhere to the drive roller 25 or the tension roller 26.

  In addition, since the rib 27 and the foreign matter collecting portion 35 are integrally formed on the belt frame 24, the rib 27 and the foreign matter collecting portion 35 can be easily formed, and the cost of the transfer unit 28 can be reduced. it can.

  Next, a third embodiment of the present invention will be described. In addition, about the thing which has the same structure as the said 1st, 2nd embodiment, the description is abbreviate | omitted by providing the same code | symbol, About the effect of the invention by having the same structure Incorporate effects.

  FIG. 6 is a perspective view of a transfer unit according to the third embodiment of the present invention.

  In this case, toner, paper dust, or the like is transferred along the running direction of the transfer belt 12 to the belt frame 24 between the shafts of the drive roller 25 and the tension roller 26 and in the vicinity of both ends in the width direction of the transfer belt 12. In order to prevent foreign matter from entering the transfer unit 28, the ribs 40 are formed integrally so as to protrude upward.

  The tension roller in the belt frame 24 prevents the toner from adhering to the transfer rollers 22Bk, 22Y, 22M, and 22C, the drive roller 25, or the tension roller 26 even if foreign matter enters the transfer unit 28. Five box-shaped foreign matter collecting portions 35 are formed between the transfer roller 26B and the transfer roller 22Bk, between the transfer rollers 22Bk, 22Y, 22M, and 22C, and between the transfer roller 22C and the drive roller 25.

  Further, slits 40a are formed at both ends of each foreign matter collecting portion 35 in the rib 40 at an angle of 45 ° inward of the belt frame 24 with respect to the running direction of the transfer belt 12 every 2 mm. Is done. However, the slit 40 a is not formed in the vicinity of the transfer roller 22, the drive roller 25, and the tension roller 26.

  Further, in the portion where the slit 40 a is formed in the rib 40, the rib 40 is generated from the outside of the transfer unit 28 by being generated by the air flow generated by the running of the transfer belt 12 and the cooling fan disposed in the apparatus main body. Due to the synergistic action of the air flow impinging on the toner, foreign matter such as toner falling from the image forming units 11Bk, 11Y, 11M, and 11C and paper dust adhering to the outside of the rib 40 is introduced into the foreign matter collecting section 35 through the slit 40a. The

  Accordingly, foreign matter such as toner and paper dust can be collected by the foreign matter collecting unit 35, so that the foreign matter does not contact and adhere to the inner peripheral surface of the transfer belt 12. As a result, the toner does not adhere to the inner peripheral surface of the transfer belt 12 and does not adhere to the drive roller 25 or the tension roller 26.

  Further, since the transfer unit 28 is periodically replaced as a consumable item, the transfer unit 28 can be used as a simple waste toner collecting container, and the printer can be used continuously in a clean state.

  By the way, in each of the above embodiments, foreign matter may adhere to the surface of the drive roller 25 as printing is repeated, but the toner once attached to the drive roller 25 can be easily removed from the drive roller 25. I can't.

  Therefore, a fourth embodiment of the present invention in which the toner attached to the drive roller can be easily formed will be described. In addition, about the thing which has the same structure as 1st-3rd embodiment, the description is abbreviate | omitted by giving the same code | symbol, About the effect of invention by having the same structure, the effect of the embodiment Is used.

  FIG. 7 is a perspective view showing a main part of a transfer unit according to the fourth embodiment of the present invention.

  In this case, a spiral groove 45a is formed on the surface of the drive roller 45 as the first roller. Then, first and second screw portions sp1 and sp2 are formed from the center to both ends in the axial direction of the drive roller 45. In the first and second screw portions sp1 and sp2, the grooves 45a are opposite to each other. Formed in the winding direction. That is, when the tips of the first and second screw portions sp1 and sp2 are viewed from the center of the drive roller 45, a groove 45a is formed in the direction of the right screw.

  Accordingly, the foreign matter adhering to the drive roller 45 is guided to both ends of the drive roller 45 by the spiral groove 45 a as the drive roller 45 rotates, and is discharged.

  As a result, the toner once adhered to the drive roller 45 can be easily removed.

  In the present embodiment, since the surface of the groove 45a needs to be smoothed in order to discharge foreign matter, the drive roller 45 is formed, for example, by covering the surface of a metal roller with a surface layer made of rubber. In some cases, it is necessary to form the groove 45a so that the metal surface appears on the surface. Further, when the drive roller 45 is formed by, for example, coating the surface of a metal roller with a coating layer containing ceramic powder, the coating layer is not formed on the surface of the groove 45a, that is, a smooth metal surface. It is necessary to form the groove 45a so as to appear.

  The present embodiment can be combined with the first to third embodiments, and can prevent foreign matter from adhering to the surface of the drive roller 45. In this embodiment, the groove 45a is formed in the drive roller 45. However, a similar groove can be formed in the tension roller 26 as the second roller.

  Next, a fifth embodiment of the present invention will be described. In addition, about the thing which has the same structure as the said 1st-4th embodiment, the description is abbreviate | omitted by providing the same code | symbol, About the effect of the invention by having the same structure Incorporate effects.

  FIG. 8 is an enlarged view of a main part of a drive roller according to the fifth embodiment of the present invention, and FIG. 9 is a YY sectional view of FIG.

  In this case, toner reservoirs 50 as annular foreign matter reservoirs are formed at both left and right ends of the groove 45a of the drive roller 45 so as to communicate with the groove 45a. The toner reservoir 50 is formed of a circular groove having a predetermined width and depth, and a cleaning member 51 is provided to remove toner, paper powder, and the like stored in the toner reservoir 50, and the cleaning reservoir 51 is disposed. In order to accommodate the toner, paper powder, and the like removed and swept away by the member 51, a removed toner accommodating portion 52 as a removed foreign matter accommodating portion is provided.

  The cleaning member 51 is in contact with the bottom of the toner reservoir 50, and includes a brush portion 51a as a foreign matter removing member that removes foreign matter as the drive roller 45 rotates, and a holder portion 51b that holds the brush portion 51a. Prepare.

  The removed toner storage portion 52 stores the foreign matter removed from the toner reservoir 50 by the brush portion 51a. The removed toner container 52 is partitioned by a central portion of the drive roller 45 and a partition wall 53, and communicates with the foreign matter collecting unit 35 closest to the drive roller 45.

  Reference numeral 54 denotes a seal film as a seal member disposed at the lower end of the removed toner storage portion 52 so that the removed foreign matter does not leak from the toner reservoir 50.

  The cleaning member 51 includes a brush portion 51a for removing foreign matter from the toner reservoir 50. However, it is sufficient that the foreign matter can be removed from the toner reservoir 50 having a smooth surface. A blade made of an elastic material such as rubber, a film such as a polyethylene film, and the like can be used.

  Further, as in the fourth embodiment, the toner reservoir 50 and the groove 45a have the metal surface of the metal roller exposed and the surface smoothed.

  In the present embodiment, the foreign matter adhering to the drive roller 45 is conveyed along the groove 45 a and sent to the toner reservoir 50 at both ends of the drive roller 45. In the toner reservoir 50, the foreign matter is scraped off by the cleaning member 51, peeled off from the surface of the drive roller 45, stored in the removed toner storage portion 52, and then recovered in the foreign matter recovery portion 35.

  As described above, in the present embodiment, the toner discharged to both ends of the drive roller 45 can be collected by the foreign matter collecting unit 35. Accordingly, since no foreign matter is discharged into the apparatus main body, the printer can be continuously used in a clean state.

  The present embodiment can be combined with the first to third embodiments, and can prevent foreign matter from adhering to the surface of the drive roller 45. In this embodiment, the groove 45a is formed in the drive roller 45. However, a similar groove may be formed in the tension roller 26 as the second roller to form a toner reservoir. it can.

  Next, a sixth embodiment of the present invention will be described. In addition, about the thing which has the same structure as the said 1st-5th embodiment, the description is abbreviate | omitted by giving the same code | symbol, About the effect of the invention by having the same structure Incorporate effects.

  FIG. 10 is a perspective view showing a main part of a transfer unit according to the sixth embodiment of the present invention, and FIG. 11 is a cross-sectional view taken along line BB in FIG.

  In this case, the cleaning member 60 is disposed along the axial direction of the drive roller 25 as the first roller. For this purpose, a cleaning member 60 is disposed across the entire area of the drive roller 25, and the cleaning member 60 cleans the surface of the drive roller 25 and scrapes off foreign matter. The foreign matter scraped off by the cleaning member 60 is accommodated in the removed toner accommodating portion 61.

  The drive roller 25 is formed by coating the surface of a metal roller with a coating layer containing ceramic powder or the like, and the surface roughness Rmax is about 100 [μm]. The cleaning member 60 is disposed in contact with the surface of the drive roller 25, and the brush portion 60a that scrapes off foreign matter, the holder portion 60b that holds the brush portion 60a, and the scraped foreign matter does not rise. Thus, a wall portion 60c is provided as a guide portion that guides the removed toner storage portion 61.

  The removed toner storage unit 61 communicates with a foreign material recovery unit 35 closest to the drive roller 25 among the foreign material recovery units 35 formed on the belt frame 24, and the stored foreign material is recovered by the foreign material recovery unit 35. The

  Reference numeral 54 denotes a seal film as a seal member disposed at the lower end of the removed toner accommodating portion 61 so that the removed foreign matter does not leak from the surface of the drive roller 25.

  In the present embodiment, the foreign matter adhering to the surface of the drive roller 25 is always scraped off by the brush portion 60a and stored in the removed toner storage portion 61 having a guide portion having a width wider than the width of the brush portion 60a. The

  Therefore, the transfer belt 12 can always be run in a normal state. Further, since the brush portion 60a is arranged over the entire axial direction of the drive roller 25, foreign matters attached to the surface of the drive roller 25 can be reliably removed.

  The cleaning member 60 includes a brush portion 60a that scrapes off foreign matter from the surface of the drive roller 25 having a surface roughness Rmax of about 100 [μm]. However, the cleaning member 60 only needs to be able to scrape off foreign matter from the rough surface. Instead of the portion 60a, a sponge-like material made of urethane, silicone or the like can be used. Further, in a drive roller formed by coating a metal roller with a rubber surface layer, a film-like material such as a polyethylene film can be used instead of the brush portion 60a.

  In the present embodiment, as shown in FIG. 10, the wall portion 60c extends downward from the holder portion 60b. However, the wall portion 60c is not connected to the bottom portion of the removed toner accommodating portion 61, and the removed toner accommodation portion. Although the portion 61 and the foreign matter collecting portion 35 are communicated with each other, the wall portion 60c extends to the bottom of the removed toner containing portion 61, so that the removed toner containing portion 61 and the foreign matter collecting portion 35 can be partitioned.

  Note that this embodiment can be combined with the first to third embodiments, and can prevent foreign matter from adhering to the surface of the drive roller 25. In this embodiment, the drive roller 25 is provided with the cleaning member 60, the removed toner accommodating portion 61, and the like, but the tension roller 26 is provided with the same cleaning member, removed toner accommodating portion, and the like. It can be arranged.

  In each of the above embodiments, the belt unit using the transfer belt 12 that conveys the paper as a belt member is described. However, the belt unit having an intermediate belt that carries a toner image on the belt member and transfers the toner image onto the paper. Can be used.

  In each of the above-described embodiments, examples of applying to a printer as an image forming apparatus have been described. However, the present invention can be applied to a copying machine, a facsimile machine, a multifunction machine, and the like.

  The present invention is not limited to the above embodiments, and various modifications can be made based on the gist of the present invention, and they are not excluded from the scope of the present invention.

It is a perspective view of the transfer unit in the 1st embodiment of the present invention. 1 is a schematic diagram of a printer according to a first embodiment of the present invention. It is XX sectional drawing of FIG. It is a perspective view which shows the principal part of the transfer unit in the 2nd Embodiment of this invention. It is AA sectional drawing of FIG. It is a perspective view of the transfer unit in the 3rd embodiment of the present invention. It is a perspective view which shows the principal part of the transfer unit in the 4th Embodiment of this invention. It is a principal part enlarged view of the drive roller in the 5th Embodiment of this invention. It is YY sectional drawing of FIG. It is a perspective view which shows the principal part of the transfer unit in the 6th Embodiment of this invention. It is BB sectional drawing of FIG.

Explanation of symbols

12 Transfer belt 24 Belt frame 25, 45 Drive roller 26 Tension roller 27, 40 Rib 28 Transfer unit 35 Foreign matter collection part 40a Slit 45a Groove 51, 60 Cleaning member 51a, 60a Brush part 52, 61 Removal toner storage part

Claims (10)

In the belt unit disposed to face the image forming unit including the image carrier,
(A) a first roller;
(B) a second roller;
(C) a belt member stretched between the first and second rollers;
(D) having a holding member for holding the first and second rollers;
(E) The holding member includes an extending portion that is formed integrally with the holding member and extends from the holding member toward the vicinity of the inner peripheral surface of the belt member. .   The belt unit according to claim 1, wherein the extending portion is disposed at a position corresponding to an end portion in the width direction of the belt member.   The belt unit according to claim 1, wherein the holding member includes a recovery unit that collects foreign matter in a region formed by an inner peripheral surface of the belt member.   The belt unit according to claim 3, wherein a slit is formed in a portion corresponding to both end portions of the recovery portion in the extending portion. In the belt unit disposed to face the image forming unit including the image carrier,
(A) a first roller;
(B) a second roller;
(C) having a belt member stretched between the first and second rollers,
(D) A belt unit in which a spiral groove is formed on the surface of at least one of the first and second rollers from the center toward both ends.   The belt unit according to claim 5, wherein the first roller is disposed on the downstream side in the traveling direction of the belt member.   The belt unit according to claim 5 or 6, wherein a cleaning member for removing foreign matter is disposed in the groove portion. In the belt unit disposed to face the image forming unit including the image carrier,
(A) a first roller;
(B) a second roller;
(C) having a belt member stretched between the first and second rollers,
(D) A belt unit in which a cleaning member for cleaning the surface is disposed opposite to at least one of the first and second rollers.   The belt unit according to claim 7 or 8, wherein the cleaning member has a brush shape.   An image forming apparatus on which the belt unit according to any one of claims 1 to 9 is mounted.

Images