JP4492924B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing roller used in a copying machine, a printer, a facsimile machine, and the like, and a developing device including the developing roller.

  A developing device such as a copying machine, a printer, or a facsimile machine is provided with a sleeve-shaped (hollow) developing roller and a magnet roller disposed on the inside thereof. It is configured to be rotatable. Although this bearing is arranged outside the image forming portion at the center side in the longitudinal direction of the developing roller, the frictional heat generated in the bearing is transmitted to the image forming portion, and the developer near the bearing is deteriorated. Problem occurs.

  A seal member is in sliding contact with both ends of the developing roller in order to prevent the leakage of the developer from the developer container containing the developer. The developer is similarly deteriorated by the frictional heat of the seal member.

  In addition, there is a problem that a portion where the temperature distribution in the longitudinal direction of the developing roller changes sharply due to frictional heat, resulting in uneven density.

  The deterioration and uneven density of the developer due to the frictional heat become more conspicuous as the developing roller rotates at a higher speed, that is, as the image forming apparatus becomes a higher speed machine.

  In order to cope with this problem, for example, Patent Documents 1 to 4 disclose configurations that promote heat dissipation and cooling.

  Patent Document 1 discloses an invention in which the developing roller has a two-layer structure and the inner layer is formed of a copper pipe (high heat conduction layer) to uniformly uniform the temperature distribution in the axial direction of the developing roller.

  In the invention described in Patent Document 2, the heat generated on the flange member side is developed by interposing a resin material between the developing roller and the flange member fitted to both ends in the longitudinal direction of the developing roller. It is difficult to be transmitted to the rollers.

  Patent Document 3 discloses an invention in which fins are provided as heat radiating means at the end of the developing roller.

  Patent Document 4 discloses an invention in which an air passage is provided along the longitudinal direction of the developing roller, and cooling is performed by applying air to the developing roller through the passage by a blower.

JP-A-6-337579 JP-A-8-328373 JP 2000-112227 A JP 2000-229330 A

  According to the inventions disclosed in Patent Documents 1 to 4 described above, it is possible to increase the corresponding heat dissipation effect and cooling effect.

  However, in Patent Document 1, the developing roller has a double structure, in Patent Document 2, a resin material is interposed, in Patent Document 3, a fin is provided, and in Patent Document 4, an air passage and a blowing means are provided. In any case, since a special configuration is added, the configuration is complicated accordingly.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a developing device and an image forming apparatus provided with the developing device that can prevent deterioration and uneven density of a developer due to frictional heat of a bearing and a seal member with a simple configuration. It is the purpose.

The invention according to claim 1 includes: (1) a developer container that houses a developer; and (2) a developer roller that is housed in the developer container and rotatably supported, and carries the developer on an outer peripheral surface. A sleeve-shaped roller body; and (3) a clearance between the developing container and the roller body that is disposed at both ends along the longitudinal direction of the roller body and rubs against the outer peripheral surface of the both ends of the roller body. A developer leakage prevention seal that prevents the developer in the developer container from leaking out of the developer container; and (4) the developer roller that is fitted and fixed to both ends of the roller body. And a developing device including the flange member. In the present invention, the roller main body has an image forming region disposed between the both end portions. Moreover, the internal thread which engages with the external thread formed in the outer peripheral surface of the said flange member is formed in the internal peripheral surface of the said both end part side at least among the internal peripheral surfaces of the said roller main body. The developer leakage prevention seal is disposed such that the rubbing portion with the roller main body is located outside the image forming area and located away from the image forming area. The female screw is formed at least up to a boundary region between the image forming region and the other portion. Further, the flange member is disposed such that a screwed portion with the roller main body is located away from the image forming area. Further, the portion of the inner peripheral surface of the roller body faces the space except for the portion where the flange member is fitted and fixed. Then, heat generated in the rubbing portion between the developer leakage prevention seal and the roller body is conducted to the image forming area through the portion of the roller body where the female screw is formed. ing.

According to a second aspect of the present invention, there is provided: (1) a developer container that houses a developer; and (2) a developing roller that is housed in the developer container and rotatably supported, and carries the developer on an outer peripheral surface. A sleeve-like roller main body, (3) a magnet roller accommodated on the inner peripheral side of the roller main body via a gap, and configured to rotate relative to the roller main body, and (4) the length of the roller main body The developer in the developing container is disposed at both ends along the direction and slidably rubs against the outer peripheral surface of the both ends of the roller main body through the gap between the developing container and the roller main body. (5) a flange member of the developing roller that is fitted and fixed to both ends of the roller main body, and (6) a magnet roller that is relative to the flange member. Pivotable A bearing for supporting, it relates to a developing device provided with. In the present invention, the roller main body has an image forming region disposed between the both end portions. Moreover, the internal thread which engages with the external thread formed in the outer peripheral surface of the said flange member is formed in the internal peripheral surface of the said both end part side at least among the internal peripheral surfaces of the said roller main body. The developer leakage prevention seal is disposed such that a sliding portion with the developing roller is located outside the image forming area and is separated from the image forming area. The female screw is formed at least up to a boundary region between the image forming region and the other portion. Further, the flange member is disposed such that a screwed portion with the roller main body is located away from the image forming area. Further, the portion of the inner peripheral surface of the roller body faces the space except for the portion where the flange member is fitted and fixed. Then, the heat generated in the rubbing portion between the developer leakage prevention seal and the developing roller and the heat generated in the bearing are formed through the portion of the roller body where the female screw is formed. Conducted to the area.

According to a third aspect of the present invention, there is provided a feeding / conveying section for feeding / conveying a recording material, an image forming section for forming an image on the recording material conveyed by the feeding / conveying section, and the recording material formed by the image forming section. The present invention relates to an image forming apparatus including a fixing unit that fixes a recorded image on the recording material. In the present invention, the image forming unit includes the developing device according to the first or second aspect of the invention.

According to the present invention, the thickness of the portion of the roller body where the female thread is formed is thinner than the other part at a position corresponding to the bottom of the thread groove of the female thread ( that is , the direction perpendicular to the longitudinal direction of the roller body). Is smaller at the bottom of the thread groove of the female thread ). Therefore, the present invention provides a bearing that rotatably supports the heat generated in the sliding portion between the developer leakage prevention seal and the roller body or the sliding portion between the developer leakage prevention seal and the roller body and the magnet roller. The generated heat is difficult to be conducted to the image forming area of the roller body, and the deterioration and uneven density of the developer due to the developer leakage prevention seal and the frictional heat of the bearing can be prevented with a simple configuration.

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

<Embodiment 1>
FIG. 1 is a diagram schematically showing a schematic configuration of an example of an image forming apparatus (for example, a copying machine, a printer, a facsimile machine) to which a developing roller and a developing device according to the present invention are applied.

  The image forming apparatus shown in FIG. 1 includes an image forming unit 1 that forms an image (toner image) on a recording material (for example, plain paper, an envelope, a sheet-like transparent film) P, and a feeding conveyance that feeds and conveys the recording material P. A unit 2 and a fixing unit 3 that fixes a toner image on the recording material P are provided. Hereinafter, it demonstrates in order.

  The image forming unit 1 includes a photosensitive drum 11 that is rotationally driven in the direction of an arrow R11, and process devices that are arranged around the photosensitive drum 11 in almost the order along the rotational direction. The process equipment includes a charging roller 12 for charging the surface of the photosensitive drum 11, an exposure device 13 for forming an electrostatic latent image on the surface of the charged photosensitive drum 11, a developing device 14 for developing the electrostatic latent image, and a photosensitive drum by development. 11 includes a transfer roller 15 for transferring the toner image formed on the surface of the recording material P to the recording material P, a cleaning device 16 for cleaning the surface of the photosensitive drum 11 after the toner image is transferred. The developing device 14 will be described in detail later.

  The feeding / conveying unit 2 includes a paper feeding cassette 21 that stores the recording material P, a paper feeding roller 22 that feeds the recording material P from the paper feeding cassette 21, a transporting roller 23 that transports the recording material P, and a recording material. A registration roller 24 that supplies P to the transfer nip T between the photosensitive drum 11 and the transfer roller 15 at a predetermined timing is provided.

  The fixing unit 3 is disposed inside the fixing roller 31, a pressure roller 32 that is in contact with the fixing roller 31 from below and forms a fixing nip N between the fixing roller 31 and the fixing roller 31. And a heater 33 for heating the fixing roller 31.

  The image forming apparatus configured as described above forms a toner image on the recording material P as follows.

  The photosensitive drum 11 is rotationally driven in the direction of arrow R11 at a predetermined process speed (circumferential speed) by a driving means (not shown), and the surface thereof is uniformly charged to a predetermined polarity and potential by the charging roller 12. The surface of the photosensitive drum 11 after charging is subjected to scanning exposure according to image information by the exposure device 13, and the electric charge in the exposed portion is removed to form an electrostatic latent image. The electrostatic latent image is developed as a toner image by adhering powder toner in the developer stored in the developing device 14. This toner image is carried on the surface of the photosensitive drum 11 and is conveyed to the transfer nip T as the photosensitive drum 11 rotates in the direction of arrow R11.

  On the other hand, the recording material P stored in the paper feed cassette 21 is fed by the paper feed roller 22 and is transported to the registration roller 24 by the transport roller 23. After the recording material P conveyed to the registration roller 24 is temporarily stopped, the transfer roller nip portion T is transferred by the registration roller 24 so as to coincide with the timing when the toner image on the photosensitive drum 11 is conveyed to the transfer nip portion T. To be supplied. A toner image is transferred onto the surface of the supplied recording material P by the transfer roller 15.

  After the toner image is transferred, the residual toner remaining on the surface of the photosensitive drum 11 is removed by the cleaning device 16 and used for the next image formation.

  On the other hand, the recording material P after the toner image transfer is conveyed to the fixing unit 3 and is heated and pressed by the fixing roller 31 and the pressure roller 32 when passing through the fixing nip portion N, and the toner is applied to the surface. The image is fixed. After the toner image is fixed, the recording material P is discharged onto the paper discharge tray 34, whereby the image formation on one recording material P is completed.

  Next, the developing device 14 will be described in detail.

  FIG. 2 is a longitudinal section of the developing device 14, that is, a longitudinal section in a direction orthogonal to the longitudinal direction of the developing roller 41. FIG. 3 is a longitudinal section in the direction along the longitudinal direction of the developing roller 41 (a longitudinal section on one end side in the longitudinal direction). As shown in these drawings, the developing device 14 includes a developing container 40, a developing roller 41, a magnet roller 42, a stirring member 43, and a regulating blade 44. Among these, the developing container 40 is formed in a box shape and stores the developer inside. As the developer, a two-component developer having a non-magnetic powder toner and a magnetic carrier as main components can be used. The developing container 40 has an opening 40 a at a portion facing the photosensitive drum 11.

  The developing roller 41 is disposed so as to close the opening 40a. As shown in FIG. 3, the developing roller 41 includes a roller main body 45 formed in a sleeve shape, and flanges fitted to both ends of the roller main body 45 in the longitudinal direction (the left-right direction in FIG. 3, the same applies hereinafter). Member 46. However, in FIG. 3, only one flange member 46 is illustrated.

  In the present embodiment, the roller body 45 is formed in a sleeve shape having an outer diameter of φ20 and a length of 200 mm. An image forming area 47 used for development is provided in the central portion of the roller body 45 in the longitudinal direction, and a low heat conduction portion 48 is provided outside the image forming area 47 along the longitudinal direction. It is provided. A spiral groove 50 is formed on the inner peripheral surface of the low heat conducting portion 48.

  FIG. 4 shows an enlarged cross-sectional view in the vicinity of the low thermal conduction portion 48. As shown in the figure, a groove portion 50 is spirally provided on the inner peripheral surface of the low heat conducting portion 48 over the entire length in the longitudinal direction. In the present embodiment, the groove 50 is formed by a female screw, and the pitch P of the female screw is set to P = 1 mm. Further, when the thickness at the bottom portion (tooth bottom) 50a of the groove portion 50 of the low thermal conductivity portion 48 is t and the thickness at the image forming region 47 is T, t ≦ (1/2) T is satisfied. Value is set. Instead of setting the relationship between t and T, t may be set to an appropriate dimension of 0.5 mm or less alone. Further, in the present embodiment, the end portion on the center side in the longitudinal direction of the groove portion 50, that is, the end portion 48a on the center side in the longitudinal direction of the low heat conduction portion 48 (corresponding to the boundary between the low heat conduction portion 48 and the image forming region 47). ) Is located at a position on the center side of 1 mm or more from the end 46a of the flange member 46. That is, if the distance between the end portion 48a of the low heat conducting portion 48 and the end portion 46a of the flange member 46 in FIG. 4 is A, A ≧ 1 mm (A = 2 mm in the present embodiment) is set. In other words, the groove 50 is present at least 1 mm between the central end 46 a of the flange member 46 and the image forming region 47. In the present embodiment, as described above, the groove portion 50 is formed by the female screw having the pitch P = 1 mm. Thus, the gap portion 50 a between the end portion 46 a of the flange member 46 and the image forming region 47 is 1 mm or more. When the distance is provided, there exists a portion having a small area of the longitudinal section in the direction perpendicular to the longitudinal direction, that is, the bottom 50a of at least one groove 50 between them.

  As shown in FIG. 3, the flange member 46 has a male screw 51 formed on the outer peripheral surface thereof, and the male screw 51 is screwed into the groove portion 50 of the low heat conduction portion 48 described above. In addition, a shaft portion 52 protrudes outward from the center of the flange member 46 in the radial direction. The shaft portion 52 is rotatably supported by a bearing portion 40b of the developing container 40. A flange member (not shown) that is fitted (engaged) with the other end (not shown) of the roller body 45 is provided with a shaft hole that penetrates the shaft along the axis. The shaft portion 54 of the magnet roller 42 to be described next projects outward through the shaft hole. For example, a developing bias in which an AC voltage is superimposed on a DC voltage is applied to the flange member 46 from a developing bias applying power source 57 (see FIG. 2) disposed in the image forming apparatus main body (not shown). A development potential is applied to 45.

The magnet roller 42 has a magnetic pole part 53 and a shaft part 54. Of these, the magnetic pole portion 53 is formed in a roller shape having an outer diameter slightly smaller than the inner diameter of the image forming region 47 of the roller body 45 described above, and a plurality of magnetic poles (not shown) are arranged along the circumferential direction. ing. The length of the magnetic pole portion 53 in the longitudinal direction is set to be substantially the same as the length of the image forming region 47 in the longitudinal direction. The shaft portion 54 is disposed so as to penetrate the center of the magnetic pole portion 53, and both end portions thereof protrude from the magnetic pole portion 53. As shown in FIG. 3, one end portion 54 a of the shaft portion 54 is supported so as to be relatively rotatable by a bearing 55 interposed between the shaft portion 54 and the flange member 46. Further, the other end portion side of the shaft portion 54 is also supported so as to be relatively rotatable by a bearing 55 interposed between the flange member 46 and the one end portion 54a (see FIG. 6). The other end of the shaft portion 54 penetrates the through hole of the flange member described above and is supported by the developing container 40 so as not to rotate. That is, in the present embodiment, the magnet roller 42 does not move with respect to the developing container 40, and the developing roller 41 is rotatable. In the present embodiment, the developing roller 41 is rotationally driven at a peripheral speed of 300 mm / sec.

  The agitating member 43 shown in FIG. 2 rotates in the direction of the arrow R43 to agitate the developer in the developing container 40 and convey the developer toward the developing roller 41.

  The regulating blade 44 has a base end portion 44a fixed to the developing container 40, and a front end portion 44b opposed to the outer peripheral surface of the developing roller 41 through a minute gap. The regulating blade 44 regulates the layer thickness of the developer carried on the surface (outer peripheral surface) of the developing roller 41 by the magnet roller 42.

  As described with reference to FIG. 2, the developing roller 41 is disposed in the opening 40 a of the developing container 40. Therefore, in the present embodiment, as shown in FIG. 3, a seal member (developer leakage prevention seal) is provided between the developing container 40 and the developing roller 41 in order to prevent leakage of the developer from the developing container 40. 56 is provided. The seal member 56 is formed of, for example, a PFA felt having a low frictional resistance, is attached to the developing container 40, and is slid on the outer peripheral surface of the developing roller 41 over almost a half circumference. The distance B between the end portion 56a of the seal member 56 and the end portion 48a of the low heat conducting portion 48 is set to satisfy B ≧ 0.5 mm (B = 1 mm in the present embodiment). However, the distance B is a dimension along the longitudinal direction of the developing roller 41.

  In the developing device 14 configured as described above, when developing the electrostatic latent image on the photosensitive drum 11, the developing roller 41 is rotationally driven at a peripheral speed of 300 mm / sec in the direction of arrow R41 in FIG. The developer in the developing container 40 is stirred by the stirring member 43 and conveyed toward the developing roller 41. The developer is magnetically supported on the surface of the developing roller 41 by the magnetic force of the magnet roller 42, and the toner is electrically attached to the surface of the carrier by the tribo. The developer magnetically carried on the surface of the developing roller 41 is conveyed in the same direction by the rotation of the developing roller 41 in the direction of arrow R41, and the layer thickness is regulated when passing through the regulating blade 44. Further, the developer is transported to the development position D facing the surface of the photosensitive drum 11 by the rotation of the developing roller 41. At this time, a developing bias is applied from the developing bias applying power source 57 to the developing roller 41, whereby the toner in the developer is attached to the electrostatic latent image, and the electrostatic latent image is developed as a toner image.

  In the developing device 14 described above, since the developing roller 41 rotates with respect to the developing container 40 and the magnet roller 42 that are fixedly arranged, frictional heat is generated from the bearing 55 and the seal member 56 shown in FIG. The frictional heat generated in the bearing 55 is transmitted to the image forming region 47 via the flange member 46 and the low thermal conduction portion 48, and the frictional heat generated in the seal member 56 is transmitted to the image forming region 47 via the low thermal conduction portion 48. .

  However, in the present embodiment, as described above, the distance A between the end portion 46a of the flange member 46 and the end portion 48a of the low heat conducting portion 48 is set to A ≧ 1 mm (more specifically, A = 2 mm). In addition, the distance B between the end portion 56a of the seal member 56 and the end portion 48a of the low heat conducting portion 48 is set to B ≧ 0.5 mm (more specifically, B = 1 mm). As a result, the frictional heat that passes through the low thermal conductivity portion 48 passes through the bottom portion 50a of the groove portion 50, that is, the portion having a small cross-sectional area in the direction orthogonal to the heat flow. It is hard to be transmitted.

  FIG. 5 shows the experimental results. In the experiment, a roller body 45 (measured product) made of SUS (stainless steel), a length of 250 mm, and an outer diameter of 20 mm was used. Further, the roller body 45 has an image forming region 47 with a length of 220 mm, low heat conductive portions 48 at both ends with a length of 15 mm, a thickness of the image forming region 47 of T = 1 mm, and a groove portion 50 of the low heat conductive portion 48. The wall thickness at the bottom 51 is t = 0.5 mm.

  The horizontal axis in the figure shows the position of the roller body 45 in the longitudinal direction when one end of the roller body 45 in the longitudinal direction is the starting point (0). The vertical axis indicates temperature. The two vertical lines L1 and L2 in the figure, that is, the vertical line L1 between 0 and 50 on the horizontal axis, and the vertical line L2 on the right side of 200 respectively indicate the positions of the end portions 48a of the low heat conduction unit 48. Show. Therefore, the left side of the vertical line L1 and the right side of the vertical line L2 correspond to the low heat conduction unit 48. The space between the vertical line L1 and the vertical line L2 corresponds to the image forming area 47.

  As can be seen from the figure, according to the roller main body 45 (solid line) described above, the temperature rise in the vicinity of both end portions in the longitudinal direction of the image forming region 47 can be suppressed lower than in the conventional case (broken line).

  As described above, according to the present embodiment, the amount of heat transferred to the image forming region 47 is reduced without causing a significant decrease in strength, although the configuration is simple, in which the spiral groove 50 is provided on the inner peripheral surface. Thus, deterioration of developer and uneven density can be effectively prevented.

  Further, according to the present embodiment, since the groove portion 50 is formed by the female screw, the flange member 46 can be screwed using this. For this reason, an appropriate fitting strength between the roller body 45 and the flange member 46 can be ensured without performing bonding or the like. Furthermore, electrical conduction between the flange member 46 and the roller body 45 can be easily obtained.

  Note that the present embodiment is not limited to two-component development and can also be applied to one-component development.

<Embodiment 2>
FIG. 6 shows a longitudinal section of the developing roller 60 according to this embodiment. As shown in the figure, a spiral groove 50 may be provided over the entire length of the inner peripheral surface of the roller body 61. In this case, the image forming area 47 starts from a position on the inner side of Amm or more from the flange members 46 at both ends. According to the present embodiment, the groove portion 50 is formed over the entire length of the inner peripheral surface of the roller main body 61 as compared with the first embodiment in which the groove portion 50 is formed separately at both ends of the roller main body 45. Therefore, for example, the groove 50 can be formed by a single cutting operation, and the processing operation can be simplified and the processing time can be shortened.

<Embodiment 3>
FIG. 7 is a partially exploded perspective view of the developing roller 62 according to the present embodiment. As shown in the figure, the groove portion 50 formed on the inner peripheral surface of the low heat conducting portion 48 of the roller body 63 is formed by a plurality of spiral grooves 65a, 65b, 65c, 65d. A plurality of spiral ridges 66a to 66d (66d not shown) that can be screwed into the grooves 65a to 65d are provided. According to the present embodiment, it is possible to shorten the work time for screwing the flange member 64 into the roller body 63 when the developing roller 62 is manufactured.

  Widely used as a developing device for developing an electrostatic latent image formed on the surface of a photoreceptor and a developing roller constituting the developing device in an image forming apparatus such as an electrophotographic printer, a facsimile, a copying machine, and a composite machine thereof. can do.

1 is a diagram schematically illustrating a schematic configuration of a fixing device and an image forming apparatus to which a pressure roller according to the present invention is applied. 2 is an enlarged vertical cross-sectional view showing a configuration of a developing device. 3 is a longitudinal section in a direction along the longitudinal direction of the developing roller. It is an expansion longitudinal cross-section of the low heat conduction part vicinity. It is a figure which compares the temperature distribution of a roller main body with the conventional object and a target product. 6 is a longitudinal section of a developing roller according to a second embodiment. 6 is a partially exploded perspective view of a developing roller according to Embodiment 3. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 14 ... Developing device, 40 ... Developing container, 41 ... Developing roller, 42 ... Magnet roller, 45 ... Roller body, 46 ... Flange member, 47 ... Image forming area, 48 ... Low heat conduction part, 48a... End portion on the center side in the longitudinal direction of the low heat conduction portion, 50... Groove portion, 55... Bearing, 56 .. developer leakage prevention seal (seal member), T. ...... Wall thickness at the bottom of the groove

Claims (3)

A developer container for storing the developer;
A sleeve-like roller body of a developing roller that is accommodated in the developing container and rotatably supported, and carries the developer on an outer peripheral surface;
The developer in the developer container is disposed at both ends along the longitudinal direction of the roller body, and slidably rubs against the outer peripheral surface of the both ends of the roller body to allow the developer in the developer container to pass through the gap between the developer container and the roller body A developer leakage prevention seal for preventing leakage to the outside of the developer container;
A flange member of the developing roller that is fitted and fixed to each of the both ends of the roller body,
The roller body has an image forming area disposed between the both ends,
On the inner peripheral surface of at least both ends of the inner peripheral surface of the roller body, a female screw is formed that is screwed into a male screw formed on the outer peripheral surface of the flange member.
The developer leakage prevention seal is disposed such that a rubbing portion with the roller main body is located outside the image forming area and located away from the image forming area,
The female screw is formed at least up to a boundary region between the image forming region and the other part,
The flange member is disposed such that a screwed portion with the roller body is positioned away from the image forming region,
Other than the portion of the inner peripheral surface of the roller body where the flange member is fitted and fixed, it faces the space,
Heat generated in a rubbing portion between the developer leakage prevention seal and the roller body is conducted to the image forming region through a portion of the roller body where the female screw is formed;
A developing device. A developer container for storing the developer;
A sleeve-like roller body of a developing roller that is accommodated in the developing container and rotatably supported, and carries the developer on an outer peripheral surface;
A magnet roller housed on the inner peripheral side of the roller body via a gap and configured to rotate relative to the roller body;
The developer in the developer container is disposed at both ends along the longitudinal direction of the roller body, and slidably rubs against the outer peripheral surface of the both ends of the roller body to allow the developer in the developer container to pass through the gap between the developer container and the roller body A developer leakage prevention seal for preventing leakage to the outside of the developer container;
A flange member of the developing roller that is fitted and fixed to the both ends of the roller body;
A bearing that rotatably supports the magnet roller on the flange member;
The roller body has an image forming area disposed between the both ends,
On the inner peripheral surface of at least the both end portions of the inner peripheral surface of the roller main body, a female screw that is screwed to a male screw formed on the outer peripheral surface of the flange member is formed.
The developer leakage prevention seal is disposed such that a rubbing portion with the roller main body is located outside the image forming area and located away from the image forming area,
The female screw is formed at least up to a boundary region between the image forming region and the other part,
The flange member is disposed such that a screwed portion with the roller main body is positioned away from the image forming region,
Other than the portion of the inner peripheral surface of the roller body where the flange member is fitted and fixed, it faces the space,
The heat generated in the rubbing portion between the developer leakage prevention seal and the developing roller and the heat generated in the bearing are transferred to the image forming area through the portion of the roller body where the female screw is formed. Conducted,
A developing device. A feeding / conveying section for feeding / conveying a recording material, an image forming section for forming an image on the recording material conveyed by the feeding / conveying section, and an image formed on the recording material by the image forming section on the recording material An image forming apparatus including a fixing unit for fixing;
3. The image forming apparatus, wherein the image forming unit includes the developing device according to claim 1 or 2.

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