JP2015082056A - Image forming apparatus and developing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that includes a photoreceptor unit arranged in an apparatus body and a developing unit detachably attached to the apparatus body, where the developing unit is movable between a contact position and a separation position with respect to the photoreceptor unit while being attached to the apparatus body, the image forming apparatus effectively performing the cooling of the developing unit without causing an increase in size of the apparatus and preventing the fusion and adhesion of developer and the generation of solidified material.SOLUTION: A developing unit 30 is provided with a projection 35 having higher thermal conductivity than that of a housing 36. An apparatus body 1 is provided with a guide groove 19 into which the projection 35 is engaged, when the developing unit 30 is attached and detached to/from the apparatus body, to guide the attachment and detachment of the developing unit 30. When the developing unit 30 is moved from a separation position to a contact position while being attached to the apparatus body 1, the projection 35 is detached from the guide groove 19 to form a space 81 between the projection 35 and the guide groove 19, and the heat generated in the developing unit 30 is released into the space 81 through the projection 35.

Description

  The present invention relates to an image forming apparatus and a developing unit. More specifically, the developing unit is detachably attached to the apparatus main body, and is in a contact position and a separated position with respect to the photoconductor unit in a state of being mounted on the apparatus main body. The present invention relates to a movable image forming apparatus and developing unit.

  An image forming apparatus using an electrophotographic system such as a printer, a facsimile, or a copying machine includes a developing unit that develops an electrostatic latent image formed on the surface of a photosensitive drum with toner to form a toner image. In the developing unit, for example, as shown in FIG. 12, conveying screws 32a and 32b for conveying a developer (not shown) having toner and a carrier while stirring are provided in a housing 36 via bearings 92a and 92b. Is provided. The rotation shafts of the conveying screws 32a and 32b protrude outward beyond the bearings 92a and 92b, and gears 91a and 91b are attached to the ends of the bearings 92a and 92b. Rotational force from a drive source (not shown) is transmitted to the rotation shaft via gears 91a and 91b, the conveying screws 32a and 32b rotate, and the conveying screw 32b conveys the developer in the right direction in FIG. The screw 32a conveys the developer in the left direction in FIG. A partition wall 60 is formed between the transport screw 32 a and the transport screw 32 b, and openings 61 are formed in the partition wall 60 at both ends in the axial direction, and the developer passes through the openings 61. Moves from the conveying screw 32b side to the conveying screw 32a side. As a result, the developer circulates in the housing 36.

  On the end side of the conveying screw 32b, a reversely wound conveying screw 94 and a disc-shaped stop plate 95 are provided so that the pressure from the developer is not directly applied to the inner wall of the housing 36 or the bearing 92b. In some cases, a part of the developer conveyed by the conveying screw 32b gets over the reverse winding conveying screw 94 and the stop plate 95 and enters the bearing 92b. The bearing 92b is disposed with a predetermined space from the inner wall of the housing 36, but the developer may reach the seal member 93b provided in front of the bearing 92b through the space. The seal member 93b is usually made of a ring-shaped rubber material, and becomes hotter than the periphery due to friction with the rotation shaft of the conveying screw 32b. For this reason, when the rotation speed of the conveying screw 32b increases and the seal member 93b becomes high temperature and rises to near the melting temperature of the developer, the developer in the vicinity of the seal member 93b melts and adheres to the seal member 93b and the rotating shaft. Or may be cooled to produce a solidified product. If such melted fixing of the developer or generation of a solidified product occurs, the rotational torque of the conveying screw 32b may increase, or a part of the solidified product may be mixed into the developer in the housing 36 and cause image deterioration. there were.

  Therefore, for example, Patent Document 1 proposes a mechanism in which a housing for storing the developer is configured by a heat sink, a cooling fin is provided on the outer wall portion of the housing, and the cooling fin is air-cooled by a cooling fan.

JP 2007-226148 A

  However, in the proposed mechanism, since the cooling fin is provided on the entire bottom surface of the housing, there is a concern that the apparatus will be enlarged. In recent years, as the image forming speed has increased, the frictional heat between the rotating shaft of the conveying screw and the seal member has increased, and at the same time, the melting point of the developer has been lowered. Fixation and solidified product are more likely to occur.

  The present invention has been made in view of such conventional problems, and its purpose is to effectively cool the developing unit without incurring an increase in the size of the apparatus, and to fix the melted and solidified developer. It is to prevent generation.

  An image forming apparatus according to the present invention that achieves the above object includes a photosensitive unit disposed in an apparatus main body, and a developing unit that is detachable from the apparatus main body, and the developing unit is attached to the apparatus main body. In this state, the apparatus has a protrusion that can move to a contact position and a separation position with respect to the photosensitive unit, and that has a higher thermal conductivity than the housing of the developing unit. A guide groove for guiding the attachment and detachment of the development unit when the projection is engaged, and when the development unit is attached to the apparatus main body and moves from the separation position to the contact position, The protrusion is separated from the guide groove, a space is formed between the protrusion and the guide groove, and heat generated in the developing unit is radiated to the space through the protrusion. And

  Here, it is preferable that a space formed between the protrusion and the guide groove constitutes a part of the air flow path.

  The developing unit carries the developer on the surface, rotates the developer to a position facing the photoreceptor of the photoreceptor unit, and the developer in a direction parallel to the rotation axis direction of the developing roller. In the case of having at least one conveying member that rotates and conveys, it is preferable that the protrusion is formed in the vicinity of the bearing portion on the driving side of the conveying member.

  The protrusion may have a through hole.

  Further, the protrusion may have a plurality of heat radiating fins. Furthermore, you may have a guide plate which directs an airflow to the said radiation fin.

  In addition, when a plurality of the developing units are provided and a cooling fan that forms an air flow is further provided, it is preferable that the protrusion of the developing unit that is farther from the cooling fan has a larger number of the radiation fins.

  Further, according to the present invention, the image forming apparatus can be detachably attached to the apparatus main body, and can be moved to a contact position and a separation position with respect to the photosensitive unit while being attached to the apparatus main body. A protrusion having a higher thermal conductivity than the body, the protrusion engages with a guide groove provided in the apparatus main body, guides attachment / detachment to / from the apparatus main body, and is attached to the apparatus main body When the state moves from the separated position to the contact position, the protrusion is detached from the guide groove, a space is formed between the protrusion and the guide groove, and the heat generated in the housing causes the protrusion to A developing unit is provided in which heat is radiated to the space.

  Here, the developer is carried on the surface, the developing roller that rotates and conveys the developer to a position facing the photoreceptor of the photoreceptor unit, and the developer that rotates in a direction parallel to the rotation axis direction of the developing roller. In the case of having at least one conveying member, the protrusion is preferably formed in the vicinity of the bearing portion on the drive side of the conveying member.

  The protrusion may have a through hole.

  Further, the protrusion may have a plurality of heat radiating fins. Furthermore, the protrusion may have a guide plate that directs an air flow toward the heat radiating fin.

  In the image forming apparatus and the developing unit of the present invention, heat generated in the developing unit is dissipated using a protrusion provided on the developing unit that guides and assists the attachment and detachment of the developing unit with respect to the apparatus main body. The development unit can be effectively cooled without causing the development, and the developer can be prevented from being melted and fixed and the solidified product can be prevented.

1 is a schematic diagram illustrating an example of an image forming apparatus and a developing unit according to the present invention. FIG. 6 is a vertical sectional view of the process cartridge when the developing unit is in a contact position. FIG. 6 is a vertical sectional view of the process cartridge when the developing unit is at a separation position. It is a perspective view of a developing unit. It is a perspective view explaining the attachment to the housing | casing of a protrusion. FIG. 6 is a partial view of a developing unit in which a protrusion is attached to a housing. FIG. 5 is a partial cross-sectional view of a developing unit near a protrusion. It is explanatory drawing at the time of providing the protrusion in which the number of radiation fins differs in a housing | casing. It is a perspective view which shows other embodiment of a protrusion. It is a front view of the protrusion of FIG. It is the sectional view on the AA line of FIG. It is a fragmentary sectional view of the conventional developing unit.

  Hereinafter, an image forming apparatus and a developing unit according to the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. The apparatus main body 1 includes a reading unit 100 that reads a document image, a printer unit 200 that prints an image, and an operation display unit 300 that serves as an interface with a user. The reading unit 100 is a known unit that reads an image of a document placed on a document glass plate (not shown) by moving a scanner, and is converted into an electrical signal for each color by an image sensor and sent to the printer unit 200. It is done. Further, when an image signal converted into electronic data is received from a facsimile or a separate personal computer, it is sent directly to the printer unit 200.

  The printer unit 200 includes an endless intermediate transfer belt (intermediate transfer member) 40 at the center of the inside thereof. The intermediate transfer belt 40 is suspended substantially horizontally between the roller 41 and the roller 42 and rotates counterclockwise. Below the intermediate transfer belt 40, four process cartridges 10Y, 10M, 10C, 10K (hereinafter referred to as “process cartridges”) corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K). 10 ”may be collectively referred to). A secondary transfer roller 54 is in pressure contact with the roller 42 around which the intermediate transfer belt 40 is suspended with the intermediate transfer belt 40 interposed therebetween. The roller 41 is provided with a cleaning device 43 for cleaning the surface of the intermediate transfer belt 40. A primary transfer roller 44 is disposed inside the intermediate transfer belt 40 at a position corresponding to the photoreceptor 21.

  Above the intermediate transfer belt 40, toner containers 60Y, 60M, 60C, and 60K filled with replenishment toner for each color are detachably attached to the apparatus main body 1, respectively. From here, the toner is supplied to the developing unit 30 through a toner conveyance path (not shown) so that the toner density in the developing unit 30 (shown in FIG. 2) becomes constant.

  A cooling fan 70 is provided on the upstream side (the left side in FIG. 1) of the process cartridge 10Y on the most upstream side in the rotation direction of the intermediate transfer belt 40.

  An exposure apparatus 11 is provided below the process cartridge 10 with a predetermined space (air flow channel 71) therebetween as described later. The light emitted from the window of the exposure device 11 irradiates the surface of the photosensitive member 21 (shown in FIG. 2) through the gap between the photosensitive member unit 20 (shown in FIG. 2) and the developing unit 30 (shown in FIG. 2). An electrostatic latent image is formed on the surface of the photoreceptor 21.

  A cassette 51 is disposed below the exposure device 11. In the cassette 51, transfer materials 50 such as paper and film are stacked and stored, and are drawn one by one from the uppermost transfer material 50 to the transport path A by the paper feed roller 52. The transfer material 50 drawn to the conveyance path A is conveyed to the registration roller pair 53 by a conveyance roller. Then, the transfer material 50 is fed by the registration roller pair 53 to the nip portion between the intermediate transfer belt 40 and the secondary transfer roller 54 in synchronism with the rotation of the toner image on the surface of the intermediate transfer belt 40, where the toner image is transferred. Transferred onto the transfer material 50.

  The transfer material 50 onto which the toner image has been transferred is sent to the fixing device 55 through the conveyance path. In the fixing device 55, the transfer material 50 is heated and pressurized, and the toner image on the transfer material 50 is melted and fixed on the transfer material 50. Then, the transfer material 50 is discharged to a paper discharge tray.

  FIG. 2 shows a vertical sectional view of the process cartridge 10. Each process cartridge has the same configuration. FIG. 2 is a vertical cross-sectional view when the developing unit 30 is in a contact position with respect to the photoreceptor unit 20. The process cartridge 10 includes a photoconductor unit 20 and a developing unit 30. The photoconductor unit 20 includes a cylindrical and rotatable photoconductor 21, a charging device 22 that uniformly charges the surface of the photoconductor 21 around the photoconductor 21, and a toner image transferred to the intermediate transfer belt 40. And a cleaning device 23 that collects toner remaining on the surface of the photoconductor 21. The photoreceptor unit 20 is attached to and detached from the apparatus main body 1 while being guided by a support rail 101 provided in the apparatus main body 1.

  The developing unit 30 includes a housing 36, a rotatable developing roller 31 that is provided in the housing 36, supplies a toner to the electrostatic latent image formed on the surface of the photoreceptor 21, and visualizes the toner, and a toner And a developer (not shown) composed of a carrier and two carrier screws (conveying members) 32 a and 32 b for agitating and supplying the developer to the developing roller 31, and a protrusion 35 provided on the outer surface of the housing 36. The developing unit 30 is detachably attached to the apparatus body 1. The developing unit 30 can be attached to and detached from the apparatus main body 1 by engaging the protrusion 35 provided on the outer surface of the housing 36 into the guide groove 19 provided in the apparatus main body 1 and sliding the developing unit 30. Done.

  Further, the developing unit 30 is provided in the apparatus main body 1 so as to be able to swing between a contact position and a separated position with respect to the photosensitive unit 20 around the swing shaft 33. Specifically, in a state where the developing unit 30 is mounted on the apparatus main body 1, an operation lever (not shown) provided on the apparatus main body is rotated so that a protrusion (not shown) of the operation lever is attached to the developing unit 30. Abutting on the abutting portion 34, the developing unit 30 is pushed upward about the swing shaft 33. As a result, the developing unit 30 contacts the photoconductor unit 20. On the other hand, when the operation lever is rotated in the opposite direction, the force pushing up the developing unit 30 is released, and the developing unit 30 rotates counterclockwise around the swing shaft 33 by its own weight, and the photosensitive unit 20. Separate from. FIG. 3 is a vertical cross-sectional view when the developing unit 30 is in a separated position with respect to the photoconductor unit 20.

  FIG. 4 shows a perspective view of the developing unit 30. The protrusion 35 is provided on a portion of the outer surface of the housing 36 that is located on the distal end side in the mounting direction with respect to the apparatus main body 1, that is, on the back side in the apparatus main body 1. Further, a notch (not shown) is formed on the back side of the main body of the guide groove 19 so that the protrusion 35 can swing.

  FIG. 5 is a perspective view for explaining the attachment of the protrusion 35 to the housing 36, and FIG. 6 is a view in which the protrusion 35 is attached to the housing 36. The protrusion 35 includes a base 351, a plurality of plate-like heat radiation fins 352 formed at a predetermined interval in the mounting direction of the developing unit 30, and a guide plate that guides the airflow generated by the cooling fan 70 to the heat radiation fin 352. 353, and these are integrally formed of a material having a higher thermal conductivity than the housing 36. A heat radiating fin 352 is inserted into the guide groove 19 (shown in FIGS. 2 and 3) of the apparatus main body 1. The protrusion 35 is detachably attached to the housing 36 with a screw (not shown) or the like. In this way, by making the projection 35 separate from the housing 36, the projection 35 can be made common to different types of development units 30, and in the case of an apparatus having a low image forming speed. It is also possible not to provide the protrusion 35. Further, if the development positions and the number of the heat dissipating fins 352 and the notch of the corresponding guide groove 19 are made different for each development unit 30, the development unit 30 having a different development color may cause an error in the apparatus main body 1. It can be prevented from being attached to the position.

  FIG. 7 shows a partial cross-sectional view of the vicinity of the protrusion 35 and the bearing 92 b of the developing unit 30. A seal member 93b for preventing the developer from entering is provided on the inner side in the axial direction of the drive-side bearing 92b provided with the gear 91b of the rotation shaft of the conveying screw 32b. In the past, there has been a problem of melting and fixing of the developer to the rotating shaft and generation of a solidified product due to frictional heat between the seal member 93b and the rotating shaft of the conveying screw 32b. Since the protrusion 35 having a higher thermal conductivity than the housing 36 is provided at a position facing the bearing 92b by cutting out a part of the body 36, the heat generated by the seal member 93b or the like is generated by the protrusion 35. The temperature rise due to frictional heat near the seal member 93b is suppressed. The housing 36 may be provided with a through hole reaching the bearing 92b, and the protrusion 35 may be provided so as to be in direct contact with the bearing 92b. However, the developer may leak from the through hole. It is desirable to provide the projection 35 at a position facing the bearing 92b via the bearing.

  The material of the protrusion 35 is not particularly limited as long as it has a higher thermal conductivity than the housing 36. For example, a soft material such as a resin is preferable because it can be easily adapted to the shape of the housing 36. Moreover, you may comprise with a metal material from a point with high heat conductivity.

  In the image forming apparatus having such a configuration, when the developing unit 30 is mounted on the apparatus main body 1 and is in a contact position with respect to the photosensitive unit 20, that is, in a state where image formation is possible, the cooling fan 70 is operated under predetermined conditions. Driven. Then, as shown in FIG. 1, the air below the process cartridges 10Y, 10M, 10C, and 10K passes through the air flow path 71 formed between the process cartridges 10Y, 10M, 10C, and 10K and the exposure apparatus 11. Sucked. At this time, as shown in FIG. 2, a space 81 is formed between the protrusion 35 of the developing unit 30 and the guide groove. Since the space 81 constitutes a part of the air flow path 71, the heat generated in the seal member 93b, the bearing 92b, and the like of the developing unit 30 passes through the housing 36 and protrudes into the protrusion 35 (mainly the radiation fin). 352) radiates heat into the air flowing through the air flow path 71. Further, since the air flow path 71 is formed below the developing unit 30, entrainment of toner fumes generated around the developing roller 31 is suppressed, and diffusion of the toner fumes into the developing unit 30 and the apparatus main body 1 is suppressed. Is suppressed. The air discharged from the cooling fan 70 cools around the cleaning device 43, then flows substantially horizontally above the intermediate transfer belt 40 to further cool the intermediate transfer belt 40, and then from the back of the apparatus main body 1. It is discharged outside.

  In the image forming apparatus illustrated in FIG. 1, when each developing unit 30 is cooled by driving the cooling fan 70, the cooling air amount is different between the developing unit 30 </ b> Y closest to the cooling fan 70 and the developing unit 30 </ b> K farthest from the cooling fan 70. There is a possibility that the developing unit 30K separated from the 70 cannot be sufficiently cooled. For this reason, it is conceivable to increase the suction amount of the cooling fan 70 so that a sufficient amount of cooling air can be obtained in the developing unit 30K farthest from the cooling fan 70. However, there is a possibility that toner fumes generated around the developing roller 31 may be entrained. is there. Therefore, for example, as shown in FIG. 8, the heat radiation effect may be increased by increasing the number of the heat radiation fins 352 in the protrusion 35 of the developing unit 30 farther from the cooling fan 70. Alternatively, the shape of the projection 35 may be increased. In addition to the distance from the cooling fan 70 to the developing unit 30 and the melting temperature of the developer (toner) stored in the developing unit 30, the number of the radiating fins 352 of the protruding portion 35 and the protruding portion 35 are also considered. The shape may be changed for each developing unit 30. Thus, by changing the heat radiation fins 352 and the shape of the protrusion 35 for each developing unit 30, as described above, the notch corresponding to the protrusion 35 formed in the guide groove 19 of the apparatus main body 1 can be obtained. Depending on the combination, it is possible to prevent the developing units 30 having different developing colors from being attached to the wrong position of the apparatus main body 1.

  9 is a partial perspective view of the developing unit 30 provided with the protrusions 35 of another embodiment, FIG. 10 is a front view of the protrusions 35, and FIG. 11 is a cross-sectional view taken along line AA of FIG. Each is shown. The protrusion 35 shown in these drawings has two types of through holes 354 and 355. By forming such through-holes 354 and 355 in the protrusion 35, the surface area of the protrusion 35 is increased, and the heat dissipation is further improved.

  In the image forming apparatus and the developing unit of the present invention, the heat generated in the developing unit 30 is dissipated using the protrusions 35 provided on the developing unit 30 for guiding and assisting the attachment / detachment of the developing unit 30 with respect to the apparatus main body 1. Therefore, it is possible to effectively cool the developing unit 30 without increasing the size of the apparatus. As a result, melt fixing of the developer and generation of a solidified product are prevented, which is useful.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 10 Developing unit 19 Guide groove 20 Photosensitive unit 31 Developing roller 32a, 32b Conveying screw (conveying member)
33 Oscillating shaft 35 Projection 40 Intermediate transfer belt 70 Cooling fan 71 Air flow path 81 Space 352 Radiation fin 353 Guide plate 354, 355 Through hole

Claims (12)

A photosensitive unit disposed in the apparatus main body, and a developing unit detachably attached to the apparatus main body,
The developing unit is movable in a contact position and a separated position with respect to the photoconductor unit in a state of being mounted on the apparatus main body, and has a protrusion having a higher thermal conductivity than the housing of the developing unit. And
The apparatus main body has a guide groove that guides attachment / detachment of the developing unit by engaging the protrusion when the developing unit is attached / detached,
When the developing unit is mounted on the apparatus main body and moves from the separation position to the contact position, the protrusion is detached from the guide groove, and a space is formed between the protrusion and the guide groove. An image forming apparatus, wherein heat generated in a developing unit is radiated to the space through the protrusion.   The image forming apparatus according to claim 1, wherein a space formed between the protrusion and the guide groove forms a part of an air flow path. The developing unit carries the developer on the surface, rotates the developer to a position facing the photoreceptor of the photoreceptor unit, and the developer in a direction parallel to the rotation axis direction of the developing roller. And at least one conveying member for rotational conveyance,
The image forming apparatus according to claim 1, wherein the protrusion is formed in the vicinity of a bearing portion on a driving side of the conveying member.   The image forming apparatus according to claim 1, wherein the protrusion has a through hole.   The image forming apparatus according to claim 1, wherein the protrusion has a plurality of heat radiating fins.   The image forming apparatus according to claim 5, wherein the protrusion has a guide plate for directing an air flow toward the heat radiating fin.   7. The image according to claim 5, further comprising a plurality of the developing units, further including a cooling fan that forms an air flow, and the protrusions of the developing unit farther from the cooling fan have a plurality of the radiation fins. Forming equipment. It is detachable with respect to the apparatus main body of the image forming apparatus, and can be moved to a contact position and a separation position with respect to the photosensitive unit while being mounted on the apparatus main body.
Has a protrusion with higher thermal conductivity than the housing,
The protrusion engages with a guide groove provided in the apparatus main body, guides attachment / detachment to the apparatus main body,
When the device is mounted on the apparatus main body and moved from the separated position to the contact position, the protrusion is detached from the guide groove, and a space is formed between the protrusion and the guide groove, and is generated in the housing. The developing unit is radiated to the space through the protrusions. A developing roller that carries the developer on the surface and rotates and conveys the developer to a position facing the photoreceptor of the photoreceptor unit, and at least one that rotates and conveys the developer in a direction parallel to the rotation axis direction of the developing roller. Two conveying members,
The developing unit according to claim 8, wherein the protrusion is formed in the vicinity of a bearing portion on a driving side of the conveying member.   The developing unit according to claim 8, wherein the protrusion has a through hole.   The developing unit according to claim 8, wherein the protrusion has a plurality of heat radiation fins.   The developing unit according to claim 11, wherein the protrusion has a guide plate for directing an air flow toward the heat radiating fin.