JP4926103B2 - Toner cartridge and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a toner cartridge that is detachably attached to an electrophotographic image forming apparatus and an image forming apparatus using the same.

  In an electrophotographic image forming apparatus such as a laser printer, a copying machine, or a multifunction machine, a toner cartridge that contains toner is detachably mounted, and the toner in the toner cartridge is gradually consumed in a printing process. When the toner in the toner cartridge is exhausted, the toner cartridge is replaced with a new toner cartridge, and the supply of toner from the new toner cartridge is continued.

  7A and 7B are a rear view showing a conventional toner cartridge and a cross-sectional view showing the vicinity of the back of the toner cartridge. The toner cartridge 101 includes a cartridge main body housing 102 containing toner, and a toner stirring member 103 provided in the cartridge main body housing 102 and rotatably supported. When the toner cartridge is detachably attached to the image forming apparatus, a rotation output shaft (not shown) of the image forming apparatus is engaged with and connected to the connection end 104a of the rotation shaft portion 104 of the toner stirring member 103, A rotational driving force is transmitted from the rotation output shaft of the image forming apparatus to the rotation shaft portion 104 of the toner stirring member 103, the toner stirring member 103 is rotated, and the toner in the cartridge body housing 102 is stirred.

  A driving gear 105 is fixed to one end of the rotating shaft portion 104, and the driving gear 105 rotates together with the rotating shaft portion 104. The driving gear 105 meshes with a gear fixed to a rotating shaft portion of a toner conveying member (not shown) rotatably supported like the toner agitating member 103 so that the rotational driving force is supplied to the toner conveying member. To communicate.

  Here, the rotation shaft portion 104 of the toner agitating member 103 is inserted through the bearing hole 102b of the side wall 102a of the cartridge main body housing 102 and through the bearing hole 106a of the sleeve 106 fixed to the side wall 102a. It is rotatably supported by 102b and 106a.

  Since one end side of the rotating shaft portion 104 of the toner agitating member 103 is supported by the two bearing holes 102b and 106a in this way, the rotating shaft portion 104 is supported with high accuracy, and the rotation shaft portion 104 is blurred. Can be suppressed.

As is well known, various high-precision bearings have been proposed. For example, in Patent Document 1, a bearing is used to support a rotor of an electric roots compressor, and the bearing and its peripheral members are made of the same material so that the thermal expansion coefficients of these members are matched. In addition, the change in the clearance between the members due to the temperature change is suppressed, and the axial support accuracy of the rotor is increased.
JP 2006-183541 A

  By the way, the toner in the cartridge body housing 102 is easily solidified by moisture absorption or the like. When the toner is solidified, the toner stirring member 103 becomes difficult to rotate, and a large rotational load acts on the transmission path of the rotational driving force including the rotation shaft portion 104 of the toner stirring member 103.

  In particular, in the bearing hole 106a that supports one end side of the rotating shaft portion 104 of the toner stirring member 103, when a large rotational load acts on the rotating shaft portion 104, the outer peripheral surface of the rotating shaft portion 104 contacts the inner peripheral surface of the bearing hole 106a. Was pressed and brought into close contact with each other, the contact area between the inner and outer peripheral surfaces increased, and a large resistance was generated between them. As a result, the rotational torque of the rotating shaft portion 104 becomes very large, causing various problems. For example, a large rotational torque acts on the connecting end 104a of the rotating shaft 104, and the connecting end 104a is deformed to cause tooth skipping, or tooth skipping occurs in the gear unit on the image forming apparatus side. As a result, rotation blur, rotation loss, and rotation unevenness occurred.

  If the inner diameter of the bearing hole 106a is increased to increase the clearance between the rotating shaft portion 104 and the bearing hole 106a, the resistance between the inner peripheral surface of the bearing hole 106a and the outer peripheral surface of the rotating shaft portion 104 can be reduced. However, in this case, the rotation of the rotating shaft 104 is increased.

  Further, if a bearing such as Patent Document 1 is applied as a bearing, an increase in rotational torque of the rotating shaft portion 104 can be suppressed, but the number of parts and cost of the toner cartridge increase, and the maintenance cost of the image forming apparatus can be reduced. Get higher.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and is a toner capable of suppressing an increase in rotational load acting on the rotation shaft portion of the toner cartridge without causing an increase in the number of parts or cost. It is an object of the present invention to provide a cartridge and an image forming apparatus using the cartridge.

  In order to solve the above-described problems, a toner cartridge of the present invention includes a cartridge body housing that contains toner, and a toner stirring member that is provided in the cartridge body housing and is rotatably supported. In the toner cartridge that receives the rotational driving force from the image forming apparatus on the rotating shaft portion of the toner stirring member in a detachably mounted state, rotates the toner stirring member, and stirs the toner in the cartridge body housing. The cartridge body housing has a plurality of bearings that support the rotating shaft portion of the toner agitating member, and at least one inner peripheral surface of each bearing is in contact with the outer peripheral surface of the rotating shaft portion so that the rotating shaft portion can freely rotate. A plurality of supporting protrusions are provided.

  Further, the tips of the protrusions that are in contact with the rotating shaft portion of the toner stirring member are rounded to have a curved shape.

  Further, the clearance between each bearing of the cartridge body housing and the rotating shaft portion of the toner agitating member is narrowed for a bearing close to the center of the rotating shaft portion and widened for a bearing away from the center of the rotating shaft portion. ing.

  The rotating shaft portion of the toner stirring member is made of polyacetal resin.

  Further, a toner conveying member provided in the cartridge main body casing and driven to rotate together with the toner stirring member is provided.

  On the other hand, an image forming apparatus using the toner cartridge of the present invention is detachably mounted with the toner cartridge of the present invention.

  According to the toner cartridge having such a configuration, the rotating shaft portion of the toner agitating member has a plurality of bearings, and at least one inner peripheral surface of each bearing is in contact with the outer peripheral surface of the rotating shaft portion. A plurality of protrusions for rotatably supporting the portion are provided. Each protrusion of the bearing contacts the outer peripheral surface of the rotating shaft portion in a state close to a point contact or a line contact, and supports the rotating shaft portion while floating from the inner peripheral surface of the bearing. For this reason, even if the toner is solidified and a large rotational load acts on the rotating shaft portion of the toner stirring member, the outer peripheral surface of the rotating shaft portion is not pressed against and closely contacted with the inner peripheral surface of the bearing. The rotational torque of the part does not increase. Therefore, the connecting end of the rotating shaft portion of the toner agitating member that receives the rotational driving force from the image forming apparatus is not deformed, and the gear unit on the image forming apparatus side does not cause tooth skipping. Thus, there is no rotation blur, rotation loss, or rotation unevenness.

  In addition, since the tip of each protrusion that contacts the rotating shaft portion of the toner agitating member is rounded and has a curved surface, the contact area between the rotating shaft portion and each protrusion is reduced, and this contact is caused by point contact or line contact. It is possible to reliably prevent an increase in the rotational torque of the rotating shaft portion.

  Further, the clearance between the bearing and the rotating shaft portion is narrowed for a bearing close to the center of the rotating shaft portion, and is widened for a bearing away from the center of the rotating shaft portion. For this reason, the rotation blur of the rotation shaft portion can be suppressed near the center of the rotation shaft portion, and at the same time, the rotation blur of the rotation shaft portion can be absorbed at a portion away from the center of the rotation shaft portion.

  The rotating shaft portion is made of polyacetal resin. This resin is highly resistant to toner and has excellent mechanical strength, so the life of the rotating shaft is prolonged and the mechanical accuracy is high, so the toner stirring member can be rotated with high precision. It becomes.

  Furthermore, since the toner conveying member is rotated together with the toner agitating member, the toner can be stably supplied by the toner conveying member.

  On the other hand, in the image forming apparatus using the toner cartridge of the present invention, since the toner cartridge of the present invention is detachably mounted, the same effects as the toner cartridge of the present invention are exhibited.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a sectional view showing an image forming apparatus according to an embodiment of the present invention. The image forming apparatus according to the present embodiment is a color laser printer that records a color image on a recording sheet, and includes an exposure unit 1, each image forming station Pa, Pb, Pc, Pd, an intermediate transfer belt unit 2, a fixing unit 3, and a sheet. A transport device 4, a paper feed tray 5, a paper discharge tray 6, and the like are provided.

  In this image forming apparatus, the recording paper is stacked and accommodated in the paper feed tray 5, pulled out from the paper feed tray 5 one by one by the pick-up roller 7-1, and transferred to the registration roller 8 by the transport roller 4-1. Be transported. Alternatively, the recording paper is placed on the manual feed tray 9, pulled out by the pickup roller 7-2, and conveyed to the registration roller 8 by the respective conveying rollers 4-4 to 4-6. The registration roller 8 temporarily stops the recording paper, aligns the leading edge of the recording paper, and records at the timing when the leading edge of the recording paper overlaps the leading edge of the toner image formed on the intermediate transfer belt 11 of the intermediate transfer belt unit 2. The sheet is conveyed to the secondary transfer roller 12.

  The image forming stations Pa, Pb, Pc, and Pd respectively form black (K), cyan (C), magenta (M), and yellow (Y) toner images, and transfer the toner images of the respective colors to the intermediate transfer belt unit. 2 is transferred to the intermediate transfer belt 11. These image forming stations Pa, Pb, Pc, and Pd include developing devices 21a to 21d, toner cartridges 22a to 22d, photosensitive drums 23a to 23d, chargers 24a to 24d, and cleaner units 25a to 25d. Etc.

  Each of the photosensitive drums 23a to 23d is pressed by the respective primary transfer rollers 26a to 26d via the intermediate transfer belt 11, and rotated at the same peripheral speed as the intermediate transfer belt 11 that moves around in the arrow direction B. The The primary transfer rollers 26 a to 26 d also rotate following the intermediate transfer belt 11 at the same peripheral speed as the intermediate transfer belt 11 that rotates in the arrow direction B.

  Each of the chargers 24a to 24d is of a roller type, a brush type, or a charger type that is in contact with the photosensitive drums 23a to 23d, and uniformly charges the surfaces of the photosensitive drums 23a to 23d.

  The exposure unit 1 includes a laser light source 1a that emits a laser beam to each of the photosensitive drums 23a to 23d, and a plurality of mirrors 1b that guide each laser beam to the respective photosensitive drums 23a to 23d. Each laser beam is irradiated on the surface of each of the photosensitive drums 23a to 23d while modulating each laser beam according to the image data, thereby forming each electrostatic latent image on the surface of each of the photosensitive drums 23a to 23d. . As the exposure unit 1, a write head in which light emitting elements such as EL and LED are arranged in an array may be used.

  Each of the toner cartridges 22a to 22d contains black (K), yellow (Y), magenta (M), and cyan (C) toners, and the toner cartridges 22a to 22d are connected to the developing devices 21a to 21d. Each color toner is supplied to the developer tank 21f.

  Each of the developing devices 21a to 21d mixes and stirs a two-component developer composed of toner and a magnetic carrier in each developer tank 21f to frictionally charge the toner and the magnetic carrier, and each photosensitive drum 23a. The charged toners of the respective colors are attached to the electrostatic latent images on the surfaces of ˜23d, and the toner images of the respective colors are formed on the surfaces of the respective photosensitive drums 23a-23d. These toner images are transferred from the photosensitive drums 23a to 23d to the intermediate transfer belt 11 and superimposed.

  The intermediate transfer belt unit 2 includes an intermediate transfer belt 11, primary transfer rollers 26 a to 26 d, a drive support roller 31, a driven support roller 32, a secondary transfer roller 12, and the like. The primary transfer rollers 26 a to 26 d and the secondary transfer roller 12 are pressed against the intermediate transfer belt 11 so as to be able to move around the roller 31 and the driven support roller 32.

  The intermediate transfer belt 11 is formed of, for example, a synthetic resin film. The secondary transfer roller 12 is supported so as to be movable to the left and right and is biased in the right direction. The intermediate transfer belt 11 is sandwiched between the secondary transfer roller 12 and the drive support roller 31 to form a nip region. The driving support roller 31 serves as a backup roller for the secondary transfer roller 12 and is driven to rotate with the nip areas between the primary transfer rollers 26a to 26d and the photosensitive drums 23a to 23d downstream. Then, the intermediate transfer belt 11 is pulled and moved around in the arrow direction B. Thereby, each nip area is stably maintained.

  Of the primary transfer rollers 26a to 26d and the photosensitive drums 23a to 23d, in order to more stably form the nip areas between the primary transfer rollers 26a to 26d and the photosensitive drums 23a to 23d, respectively. It is preferable that one of these is formed of a hard material and the other is formed of an elastic material.

  Each of the primary transfer rollers 26a to 26d has, for example, a metal shaft whose outer periphery is covered with a conductive elastic material (EPDM, urethane foam, or the like). The primary transfer rollers 26a to 26d are opposite in polarity to the toner charging polarity in a state in which the intermediate transfer belt 11 is sandwiched between the nip regions between the primary transfer rollers 26a to 26d and the photosensitive drums 23a to 23d. Are applied to the toner on the surfaces of the photosensitive drums 23a to 23d via the intermediate transfer belt 11, and the toner on the surfaces of the photosensitive drums 23a to 23d is attracted to the intermediate transfer belt 11. To transcribe. As a result, the toner images of the respective colors are transferred to the intermediate transfer belt 11 and superimposed. As the primary transfer rollers 26a to 26d, brushes or the like may be used instead of the rollers.

  The cleaning unit 34 is, for example, a cleaning blade that is in sliding contact with the surface of the intermediate transfer belt 11 and removes toner remaining on the surface of the intermediate transfer belt 11 to prevent fogging of an image to be printed next time.

  The toner images of the respective colors transferred and superimposed on the intermediate transfer belt 11 in this way are conveyed to the nip area between the drive support roller 31 and the secondary transfer roller 12 as the intermediate transfer belt 11 rotates. Then, the leading edge of each color toner image on the intermediate transfer belt 11 and the leading edge of the recording sheet conveyed by the registration roller 8 are overlapped, and the toner image of each color and the recording sheet are overlapped to form the toner image of each color. Transferred onto recording paper.

  Subsequently, the recording paper is conveyed to the fixing unit 3, where it is sandwiched between the pressure roller 3a and the heating roller 3b. As a result, the toner of each color on the recording paper is heated and melted and mixed, and the toner image of each color is fixed as a color image on the recording paper.

  Further, the recording paper is transported to the paper discharge tray 6 by the paper transport device 4, and is discharged face down here.

  Note that it is also possible to form a monochrome image using only the image forming station Pa and transfer the monochrome image to the intermediate transfer belt 11 of the intermediate transfer belt unit 2. Similarly to the color image, this monochrome image is also transferred from the intermediate transfer belt 11 to the recording paper and fixed on the recording paper.

  Further, when printing on both sides of the recording paper as well as on both sides, the image on the surface of the recording paper is fixed by the fixing unit 3 and then the recording paper is being transported by the transport roller 4-3 of the paper transport device 4. Then, the conveying roller 4-3 is stopped and then reversely rotated, the recording sheet is passed through the reversing path 4r of the sheet conveying apparatus 4, the recording sheet is reversed, and the recording sheet is guided to the registration roller 8. Similarly to the front surface of the recording paper, an image is recorded and fixed on the back surface of the recording paper, and the recording paper is discharged to the paper discharge tray 6.

  By the way, in the image forming apparatus according to the present embodiment, the toner cartridges 22a to 22d (hereinafter, the reference numerals 22a to 22d are collectively referred to as the reference numeral 22) and the developing devices 21a to 21d (hereinafter the reference numerals 21a to 21d are collectively referred to as the reference numeral 21). The toner of each color is replenished by replacing each toner cartridge 22a-22d with a new one. These toner cartridges 22a to 22d are detached and replaced by new ones by a user or a service person when the remaining amount of toner in the cartridge is low.

  FIG. 2 is a sectional view showing the developing device 21 and the toner cartridge 22 as viewed from the side. As shown in FIG. 2, the toner cartridge 22 is used by being detachably mounted on the developing device 21, and replenishes the toner in the cartridge 22 to the developer tank 21f of the developing device 21 through the replenishing hole 22f at the bottom of the cartridge 22. .

  The toner cartridge 22 includes a cartridge main body casing 41 that accommodates toner, and a toner stirring member 42 and a toner conveying member 43 that are provided in the cartridge main body casing 41 and are driven to rotate. When the toner cartridge 22 is attached to the developing device 21, one end of the rotation shaft portion 44 of the toner stirring member 42 is detachably connected to a rotation output shaft (not shown) on the image forming apparatus side. In this state, the rotation driving force of the rotation output shaft on the image forming apparatus side is transmitted to the rotation shaft portion 44 of the toner stirring member 42, and the toner stirring member 42 and the rotation shaft portion 44 rotate. Further, the rotational driving force from the image forming apparatus side is also transmitted to the shaft portion 45 of the conveying member 43, and the conveying member 43 rotates.

  Since the vicinity of both ends of the rotating shaft portion 44 is rotatably supported, the cross-sectional shape is circular, but the portion excluding the vicinity of both ends is a quadrangular prism. A film-like toner stirring member 42 is fixed. When the rotating shaft 44 rotates, the film-like toner stirring member 42 also rotates, and the toner in the cartridge main body housing 41 is stirred by the film-like toner stirring member 42.

  The toner conveying member 43 has a helical screw blade on the outer periphery of the shaft portion 45. When the shaft portion 45 rotates, the screw blade also rotates, and the screw blade in the cartridge main body housing 41 is rotated by the screw blade. The upper toner is conveyed. As the toner is conveyed, the toner drops from the replenishment hole 22f at the bottom of the cartridge 22 to the developer tank 21f of the developing device 21 and is replenished.

  3A, 3 </ b> B, and 3 </ b> C are perspective views of the toner cartridge 22 as viewed from the front, a perspective view of the toner cartridge 22 as viewed from the back, and a rear view of the toner cartridge 22. It is. 4 is a cross-sectional view showing the vicinity of the back side of the toner cartridge 22 along the line AA in FIG.

  As shown in FIGS. 3A to 3C and FIG. 4, the cartridge main body housing 41 of the toner cartridge 22 is obtained by closing the upper opening of the square columnar housing 41a with a lid 41b. A first bearing hole 46a is formed in the side wall 46, and two sleeves 47, 48 are provided concentrically on the outer side of the side wall 46. The inner side of the sleeve 47 becomes the second bearing hole 47a, and the inner side of the sleeve 48 is the first. Three bearing holes 48a are formed. The inner diameter of the first bearing hole 46a is smaller than the inner diameter of the second bearing hole 47a, and the inner diameter of the second bearing hole 47a is smaller than the inner diameter of the third bearing hole 48a.

  The rotating shaft portion 44 includes a quadrangular column portion 51 and a gear portion 52 fixed to one end of the quadrangular column portion 51. The gear portion 52 includes a drive gear 53, a large-diameter shaft 54, a medium-diameter shaft 55, a small-diameter shaft 56, and a protruding portion 57, which are integrally formed.

  The protrusion 57 of the gear portion 52 is inserted into the engagement hole 51 a at one end of the quadrangular prism portion 51 through the first bearing hole 46 a of the side wall 46 of the cartridge body housing 41. Thereby, the gear part 52 is connected and fixed to one end of the quadrangular prism part 51, and both are integrated. At the same time, the small-diameter shaft 56 of the gear portion 52 is inserted into the first bearing hole 46a of the side wall 46 of the cartridge body housing 41, and the medium-diameter shaft 55 of the gear portion 52 is inserted into the second bearing hole 47a of the sleeve 47. The large diameter shaft 54 of the portion 52 is inserted into the third bearing hole 48 a of the sleeve 48. Accordingly, one end of the rotating shaft portion 44 is pivotally supported by the first bearing hole 46a, the second bearing hole 47a, and the third bearing hole 48a.

  The gear portion 52 has a hollow structure with an opening formed on the right side in FIG. 4, and a connecting member 58 is fixed to an inner hollow portion of the medium diameter shaft 55.

  As the material of the rotating shaft portion 44, nylon resin, polyacetal resin, phenol resin, polypropylene resin, and the like are preferable, and polyacetal resin is particularly preferable. Since this polyacetal resin has high resistance to toner and excellent mechanical strength, the life of the rotating shaft is prolonged, and the mechanical accuracy is also high, so that the toner stirring member 42 can be rotated with high accuracy. Is possible.

  The vicinity of the other end of the rotating shaft 44 is pivotally supported by one or more bearing holes provided on the other side wall (not shown) of the cartridge body housing 41.

  FIG. 5 is a perspective view in which the lid 41b of the cartridge body housing 41 is removed so that the inside of the cartridge body housing 41 can be seen.

  As shown in FIGS. 4 and 5, a film-like toner stirring member 42 is superimposed on one side surface of the quadrangular column portion 51 of the rotating shaft portion 44, and the film-like toner stirring member 42 is fixed by a plurality of screws 61. Has been. A plurality of openings 42 a are formed in the film-like toner stirring member 42. When the toner is stirred by the rotation of the film-like toner stirring member 42, the toner is opened in each opening 42 a of the toner stirring member 42. To pass through. Thereby, the toner is efficiently stirred. As a material of the toner stirring member 42, for example, a PET film is preferable.

  Further, as apparent from FIG. 5, the toner conveying member 43 has a helical screw blade 43a.

  Further, the shaft portion 45 of the toner conveying member 43 is pivotally supported by a bearing hole formed in the side wall 46 on the back side of the cartridge body housing 41, and one end of the shaft portion 45 is disposed outside through the bearing hole. The drive gear 62 is fixed to one end of the protruding shaft portion 45.

  The drive gear 62 of the shaft portion 45 of the toner conveying member 43 meshes with the drive gear 53 of the rotation shaft portion 44 of the toner stirring member 42.

  The toner cartridge 22 having such a configuration is detachably attached to the developing device 21 as described above. At this time, the rotation output shaft on the image forming apparatus side is engaged with the connecting member 58 of the rotation shaft portion 44 of the toner stirring member 42, and the rotation shaft portion 44 of the toner stirring member 42 and the rotation output shaft on the image forming apparatus side are connected. Removably connected. When the rotation output shaft on the image forming apparatus side rotates, the rotation shaft portion 44 of the toner agitating member 42 also rotates, the toner agitating member 42 rotates, and the toner in the cartridge body housing 41 is transferred by the toner agitating member 42. Stir. At the same time, the rotation of the rotation shaft portion 44 of the toner agitating member 42 is transmitted to the shaft portion 45 of the toner conveying member 43 via the drive gears 53 and 62, and the toner conveying member 43 rotates to move inside the cartridge body housing 41. The toner is conveyed, and the toner is replenished from the replenishment hole 22 f at the bottom of the cartridge 22 to the developer tank 21 f of the developing device 21.

  By the way, when the toner in the cartridge main body housing 41 is solidified due to moisture absorption or the like, the toner stirring member 42 becomes difficult to rotate, and a large rotational load acts on the rotation shaft portion 44 of the toner stirring member 42. At this time, a large resistance is likely to occur between the inner peripheral surface of the third bearing hole 48a that supports the large-diameter shaft 54 closest to the end of the rotating shaft 44 and the outer peripheral surface of the large-diameter shaft 54, and this large resistance is reduced. If it cannot be reduced, the rotational torque of the rotating shaft portion 44 becomes very large, the connecting member 58 of the rotating shaft portion 44 that receives the rotational driving force from the image forming apparatus is deformed, or the image forming apparatus side There is a possibility of tooth skipping in the gear unit.

  Therefore, in the present embodiment, as shown in FIG. 4, the third bearing hole 48 a is configured so that no great resistance is generated between the inner peripheral surface of the third bearing hole 48 a and the outer peripheral surface of the large-diameter shaft 54 of the rotating shaft portion 44. A plurality of ribs 71 are provided on the inner peripheral surface of the large-diameter shaft, these ribs 71 are brought into contact with the outer peripheral surface of the large-diameter shaft 54 in a state close to line contact, and the large-diameter shaft 54 is lifted from the inner peripheral surface of the third bearing hole 48a. And support. Thereby, no great resistance is generated between the inner peripheral surface of the third bearing hole 48 a and the outer peripheral surface of the large-diameter shaft 54.

  FIGS. 6A and 6B are a perspective view and a rear view showing the toner cartridge 22 with the gear portion 52 removed so that the inner peripheral surface of the third bearing hole 48a can be easily seen.

  As is clear from FIGS. 6A and 6B, eight ribs 71 are arranged at equal intervals around the axis on the inner peripheral surface of the third bearing hole 48a and along the longitudinal direction of the rotary shaft portion 44. Is formed. Each rib 71 has a semi-cylindrical shape, and has a curved surface whose top is rounded. Each rib 71 is in contact with the outer peripheral surface of the large-diameter shaft 54 of the rotating shaft portion 44 in a state close to line contact, and supports the large-diameter shaft 54 by floating from the inner peripheral surface of the third bearing hole 48a. For this reason, even if the toner is solidified and a large rotational load acts on the rotating shaft portion 44 of the toner stirring member 42, the outer peripheral surface of the large-diameter shaft 54 is pressed against the inner peripheral surface of the third bearing hole 48a. The rotational torque of the rotating shaft portion 44 does not become excessive. Therefore, the connecting member 58 of the rotary shaft 44 that receives the rotational driving force from the image forming apparatus is not deformed, and the gear unit on the image forming apparatus side does not cause tooth skipping. , Rotation blur, rotation loss, and rotation unevenness do not occur.

  In the present embodiment, the clearance between the outer periphery of the small-diameter shaft 56 of the rotating shaft portion 44 and the inner periphery of the first bearing hole 46a is defined as the first clearance C1, and the outer periphery of the medium-diameter shaft 55 of the rotating shaft portion 44 and the second bearing hole 47a. If the clearance between the inner circumferences is the second clearance C2, and the clearance between the outer circumference of the large-diameter shaft 54 of the rotating shaft 44 and the inner circumference of the third bearing hole 48a is the third clearance C3, the first clearance C1 is 0.05 mm. The third clearance C3 is increased to 0.1 mm and the second clearance C2 is set to an intermediate value between the first and second clearances C1 and C2. That is, the clearance is narrowed for the bearing close to the center of the rotating shaft portion 44, and the clearance is widened for the bearing far from the center of the rotating shaft portion 44. For this reason, the rotation shake of the rotation shaft portion 44 can be suppressed near the center of the rotation shaft portion 44, and at the same time, the rotation shake of the rotation shaft portion 44 can be absorbed at a portion away from the center of the rotation shaft portion 44.

  As described above, in this embodiment, it is possible to prevent the rotational torque of the rotating shaft portion 44 from becoming excessive only by forming the eight ribs 71 on the inner peripheral surface of the third bearing hole 48a. It is possible to prevent rotation blur, rotation loss, rotation unevenness, and the like of the portion 44.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood.

  For example, a cylindrical rib is shown as the protrusion on the inner periphery of the bearing, but a semicircular protrusion may be applied instead. Furthermore, as long as the rotating shaft part is floated and supported and the frictional resistance between the inner peripheral surface of the bearing and the outer peripheral surface of the rotating shaft part can be reduced, protrusions of other shapes may be applied. Moreover, you may provide not only one bearing hole which supports a rotating shaft part but the several protrusion which floats and supports a rotating shaft part in the internal peripheral surface of two or more bearing holes. Further, although a laser printer is illustrated as an image forming apparatus, the present invention can be applied to a copying machine, a facsimile, a complex machine of these, or a monochrome image forming apparatus.

1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a developing device and a toner cartridge in the image forming apparatus of FIG. 1 as viewed from the side. 1A, 1B, and 1C are a perspective view of the toner cartridge as viewed from the front, a perspective view of the toner cartridge as viewed from the back, and a rear view of the toner cartridge. FIG. 4 is a cross-sectional view showing the vicinity of the back side of the toner cartridge, taken along line AA in FIG. FIG. 6 is a perspective view in which the inside of the cartridge main body casing is made visible by removing the lid of the cartridge main body casing. (A) And (b) is the perspective view and back view which show the toner cartridge of a state which removed the gear part so that the internal peripheral surface of a 3rd bearing hole became easy to see. (A) And (b) is a rear view which shows the conventional toner cartridge, and sectional drawing which shows the back side vicinity of a toner cartridge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure unit 2 Intermediate transfer belt unit 3 Fixing unit 4 Paper conveyance device 5 Paper feed tray 6 Paper discharge trays 21a to 21d Development devices 22, 22a to 22d Toner cartridges 23a to 23d Photosensitive drums 24a to 24d Chargers 25a to 25d Cleaners Unit 41 Cartridge body housing 42 Toner stirring member 43 Toner transport member 44 Rotating shaft portion 45 Shaft portion 46 Side wall 46a First bearing hole 47, 48 Sleeve 47a Second bearing hole 48a Third bearing hole

Claims (6)

A cartridge main body housing containing toner, and a toner agitating member provided in the cartridge main body housing and rotatably supported, and rotated from the image forming apparatus while being detachably attached to the image forming apparatus. In the toner cartridge that receives the driving force on the rotating shaft portion of the toner stirring member, rotates the toner stirring member, and stirs the toner in the cartridge body housing.
The cartridge body housing has a plurality of bearings that support the rotating shaft portion of the toner agitating member, and at least one inner peripheral surface of each bearing is in contact with the outer peripheral surface of the rotating shaft portion so that the rotating shaft portion can freely rotate. And a plurality of protrusions for supporting the toner cartridge.   2. The toner cartridge according to claim 1, wherein the tip of each of the protrusions in contact with the rotation shaft portion of the toner stirring member is rounded to have a curved surface shape.   The clearance between each bearing of the cartridge body housing and the rotating shaft portion of the toner agitating member should be narrowed for the bearing close to the center of the rotating shaft portion and widened for the bearing away from the center of the rotating shaft portion. The toner cartridge according to claim 1.   The toner cartridge according to claim 1, wherein the rotation shaft portion of the toner stirring member is made of polyacetal resin.   The toner cartridge according to claim 1, further comprising a toner conveying member that is provided in the cartridge main body casing and is driven to rotate together with the toner stirring member.   6. An image forming apparatus using a toner cartridge to which the toner cartridge according to claim 1 is detachably mounted.

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