JP2020095103A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can efficiently cool developing devices.SOLUTION: An image forming apparatus 100 comprises: photoreceptor drums 1a to 1d; developing devices 3a to 3d; a cooling unit 40 that cools the developing devices 3a to 3d; and a contact/separation mechanism 110 that brings a circulation tube 50 of the cooling unit 40 into contact with the developing devices 3a to 3d or separates the cooling unit from the developing devices. The cooling unit 40 has the circulation tube 50 having a heat receiving part 51a that is brought into pressure contact with the a developer container 20 and receives heat from the developer container 20, a radiator 60, and a pump 70 that circulates a cooling liquid. The contact/separation mechanism 110 has a pressing member 111 that presses the heat receiving part 51a of the circulation tube 50 against the developer container 20. The developing devices 3a to 3d are configured to approach the photoreceptor drums 1a to 1d with a pressing force of the pressing member 111.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image forming apparatus, and particularly to an image forming apparatus including a cooling unit that cools a developing device.

In an image forming apparatus, a latent image formed on an image carrier such as a photoconductor is developed by a developing device and visualized as a toner image. The developing device accommodates a developer containing toner in a developing container and disposes a developing roller for supplying the developer to the image carrier, and conveys the developer inside the developing container while stirring to the developing roller. An agitating/conveying member for supplying is supplied.

In order to ensure good image quality, it is necessary to maintain the gap (development gap) between the outer peripheral surface of the developing roller and the outer peripheral surface of the photosensitive drum with high accuracy. Therefore, an image forming apparatus is widely used in which developing pulleys are provided at both ends of the rotating shaft of the developing roller and a pressing mechanism for pressing the developing roller against the photosensitive drum is provided. In this image forming apparatus, the developing roller contacts the outer peripheral surface of the photoconductor drum and is driven to rotate with respect to the photoconductor drum, so that the developing roller rotates while maintaining a predetermined developing gap with respect to the photoconductor drum. To do.

By the way, when the stirring and conveying member of the developing device is driven, the temperature inside the developing device rises due to the frictional heat generated between the stirring and conveying member and the developer and the frictional heat generated between the developers.

Therefore, in order to suppress the temperature rise in the developing device, a heat receiving portion for receiving the heat of the developing container, a heat radiating portion for radiating the heat received by the heat receiving portion, and a cooling liquid between the heat receiving portion and the heat radiating portion are provided. An image forming apparatus including a flow path for circulation is known. The heat receiving unit is composed of a housing that comes into contact with the developing device directly or via a heat conductive sheet, and a flow path arranged in the internal space of the housing.

An image including a heat receiving portion for receiving the heat of the developing container, a heat radiating portion for radiating the heat received by the heat receiving portion, and a flow path for circulating the cooling liquid between the heat receiving portion and the heat radiating portion are provided. The forming apparatus is disclosed in Patent Document 1, for example.

JP, 2010-244010, A

However, in the conventional image forming apparatus including the heat receiving section, the heat radiating section, and the flow path, the heat of the developing device is transferred to the housing of the heat receiving section and then transferred to the flow path via air. For this reason, it is difficult to improve the heat conduction efficiency from the developing device to the flow path, so that it is difficult to efficiently cool the developing device.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus capable of efficiently cooling a developing device.

In order to achieve the above object, an image forming apparatus having a first configuration of the present invention includes an image carrier on which an electrostatic latent image is formed, and a toner which is disposed so as to face the image carrier and supplies toner to the image carrier. A developing unit for developing the electrostatic latent image formed on the image bearing member into a toner image, and a cooling unit for cooling the developing device. And a contacting/separating mechanism for contacting/separating the circulation tube of the cooling unit with respect to the pressed contact portion of the developing device. The cooling unit includes a circulation tube having a heat receiving portion that is pressed against the developing container to receive the heat of the developing container, a heat radiating portion that radiates the heat of the cooling liquid in the circulating tube, and a pump that circulates the cooling liquid. The contact/separation mechanism has a pressing member that presses the heat receiving portion of the circulation tube against the developing container. The developing device is configured to approach the image carrier by the pressing force of the pressing member.

According to the image forming apparatus of the first configuration of the present invention, the heat receiving portion of the circulation tube is pressed against the developing container by the pressing member of the contact/separation mechanism. As a result, the heat of the developing container is directly transferred to the circulation tube, so that the heat conduction efficiency from the developing container to the circulation tube can be improved. Therefore, the developing device can be cooled efficiently.

Further, the developing device is configured to approach the image carrier by the pressing force of the pressing member. With this, it is not necessary to separately provide a pressing mechanism for pressing the developing device against the image carrier, so that it is possible to suppress an increase in the number of parts.

FIG. 1 is a sectional view schematically showing the structure of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a side sectional view showing the structure of the developing device of the image forming apparatus according to the embodiment of the present invention. 1 is a perspective view showing a structure of a developing device of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing the structure around the developing device of the image forming apparatus of one embodiment of the present invention, showing a state in which the pressing member is arranged at the pressing position for pressing the holding member. FIG. 3 is a cross-sectional view showing a structure around a developing device of the image forming apparatus according to the exemplary embodiment of the present invention, and is a view showing a state in which a pressing member is arranged at a separated position separated from a holding member. FIG. 3 is a perspective view showing the structure of the bottom surface of the developing device of the image forming apparatus according to the embodiment of the present invention. 1 is a perspective view showing a cooling unit and a developing device of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a perspective view showing the cooling unit and the developing device of the image forming apparatus of one embodiment of the present invention from below. FIG. 3 is a perspective view showing the cooling unit of the image forming apparatus of one embodiment of the present invention from below. FIG. 3 is an enlarged cross-sectional view showing a structure around a holding member and a heat receiving portion of the image forming apparatus of one embodiment of the present invention. FIG. 3 is a perspective view showing a structure around a contacting/separating mechanism of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a diagram showing a structure around a contacting/separating mechanism of the image forming apparatus according to the embodiment of the present invention.

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

An image forming apparatus 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 12. In the main body of the image forming apparatus 100 (here, a color printer), four image forming units Pa, Pb, Pc, and Pd are sequentially arranged from the upstream side (the right side in FIG. 1) in the transport direction. These image forming portions Pa to Pd are provided corresponding to images of four different colors (cyan, magenta, yellow, and black), and cyan, magenta, and yellow are respectively formed by the steps of charging, exposing, developing, and transferring. And a black image are sequentially formed.

Photosensitive drums (image bearing members) 1a, 1b, 1c and 1d carrying visible images (toner images) of the respective colors are disposed in these image forming portions Pa to Pd, and further drive means (see FIG. An intermediate transfer belt (intermediate transfer member) 8 that rotates clockwise in FIG. 1 is provided adjacent to each of the image forming units Pa to Pd by a not shown). The toner images formed on the photosensitive drums 1a to 1d are sequentially primary-transferred and superimposed on the intermediate transfer belt 8 that moves while contacting the photosensitive drums 1a to 1d. Then, the toner image primarily transferred onto the intermediate transfer belt 8 is secondarily transferred onto a transfer paper P as an example of a recording medium by the action of the secondary transfer roller 9. Further, the transfer paper P to which the toner image is secondarily transferred is ejected from the main body of the image forming apparatus 100 after the toner image is fixed in the fixing unit 13. The image forming process for each of the photoconductor drums 1a to 1d is executed while rotating the photoconductor drums 1a to 1d counterclockwise in FIG.

The transfer paper P to which the toner image is secondarily transferred is housed in a paper cassette 16 arranged at the lower part of the main body of the image forming apparatus 100, and a secondary transfer roller is provided via a paper feed roller 12a and a registration roller pair 12b. 9 is conveyed to the nip portion between the intermediate transfer belt 8 and the driving roller 11. A sheet made of a dielectric resin is used for the intermediate transfer belt 8, and a seamless (seamless) belt is mainly used. Further, a blade-shaped belt cleaner 19 for removing toner and the like remaining on the surface of the intermediate transfer belt 8 is arranged on the downstream side of the secondary transfer roller 9.

Next, the image forming units Pa to Pd will be described. Around the photosensitive drums 1a to 1d that are rotatably arranged and below the photosensitive drums 1a to 1d, chargers 2a, 2b, 2c and 2d for charging the photosensitive drums 1a to 1d, and image information on the photosensitive drums 1a to 1d. To remove the developer (toner) and the like remaining on the photosensitive drums 1a to 1d, the exposure device 5 for exposing the photosensitive drums 1a to 1d, the developing devices 3a, 3b, 3c and 3d that form toner images on the photosensitive drums 1a to 1d. Cleaning units 7a, 7b, 7c and 7d are provided.

When image data is input from a host device such as a personal computer, first, the surfaces of the photoconductor drums 1a to 1d are uniformly charged by the chargers 2a to 2d, and then the exposure device 5 irradiates light according to the image data. , Electrostatic latent images corresponding to image data are formed on the photoconductor drums 1a to 1d. Each of the developing devices 3a to 3d is filled with a predetermined amount of a two-component developer containing toner of each color of cyan, magenta, yellow and black. When the ratio of the toner in the two-component developer filled in each of the developing devices 3a to 3d is below a specified value due to the formation of a toner image described later, each of the toner containers (replenishing parts) 4a to 4d is used to develop the toner. The toner is supplied to the devices 3a to 3d. The toner in the developer is supplied onto the photosensitive drums 1a to 1d by the developing devices 3a to 3d and electrostatically adheres to the toner, so that the electrostatic latent image formed by the exposure from the exposure device 5 corresponds to the electrostatic latent image. Toner image is formed.

Then, an electric field is applied between the primary transfer rollers 6a to 6d and the photoconductor drums 1a to 1d by a predetermined transfer voltage by the primary transfer rollers 6a to 6d, and cyan, magenta, yellow, and yellow on the photoconductor drums 1a to 1d are applied. The black toner image is primarily transferred onto the intermediate transfer belt 8. These four-color images are formed with a predetermined positional relationship that is predetermined for forming a predetermined full-color image. Then, in preparation for the subsequent formation of a new electrostatic latent image, the toners and the like remaining on the surfaces of the photosensitive drums 1a to 1d after the primary transfer are removed by the cleaning units 7a to 7d.

The intermediate transfer belt 8 is stretched around a driven roller 10 on the upstream side and a drive roller 11 on the downstream side, and the intermediate transfer belt 8 rotates clockwise as the drive roller 11 is rotated by a drive motor (not shown). When the rotation is started, the transfer paper P is conveyed from the registration roller pair 12b to the nip portion (secondary transfer nip portion) between the drive roller 11 and the secondary transfer roller 9 provided adjacent to the drive roller 11 at a predetermined timing. The full-color image on the intermediate transfer belt 8 is secondarily transferred onto the transfer paper P. The transfer paper P to which the toner image is secondarily transferred is conveyed to the fixing unit 13.

The transfer paper P conveyed to the fixing unit 13 is heated and pressed by the fixing roller pair 13a so that the toner image is fixed on the surface of the transfer paper P and a predetermined full-color image is formed. The transfer paper P on which the full-color image is formed is sorted in the transport direction by the branching unit 14 that is branched in a plurality of directions, and is directly (or after being sent to the double-sided transport path 18 and double-sided copied) by the discharge roller pair 15. The sheet is discharged to the discharge tray 17.

Next, the detailed structure of the developing device 3a will be described with reference to FIG. Note that FIG. 2 shows a state as viewed from the back side of the paper surface of FIG. 1, and the arrangement of each member in the developing device 3a is opposite to that in FIG. Further, in the following description, the developing device 3a arranged in the image forming portion Pa of FIG. 1 is illustrated, but the configurations of the developing devices 3b to 3d arranged in the image forming portions Pb to Pd are basically the same. Therefore, the description is omitted.

As shown in FIG. 2, the developing device 3a includes a developing container 20 in which a two-component developer (hereinafter, also simply referred to as a developer) containing a magnetic carrier and a toner is stored, and the developing container 20 is a partition wall. It is divided into an agitation transfer chamber 21 and a supply transfer chamber 22 by 20a. The stirring and feeding chamber 21 and the feeding and feeding chamber 22 are respectively provided with a stirring and feeding screw 25a and a feeding and feeding screw 25b for mixing and agitating the toner supplied from the toner container 4a (see FIG. 1) with the magnetic carrier to charge the toner. It is rotatably arranged.

Then, the developer is conveyed in the axial direction (the direction perpendicular to the paper surface of FIG. 2) while being agitated by the agitating and conveying screw 25a and the supplying and conveying screw 25b, and passes through the developer (not shown) formed at both ends of the partition wall 20a. It is circulated between the agitation transfer chamber 21 and the supply transfer chamber 22 via a path. That is, a circulation path for the developer is formed in the developer container 20 by the agitating transfer chamber 21, the supply transfer chamber 22, and the developer passage.

The developing container 20 extends obliquely to the upper right in FIG. 2, and a developing roller 31 is arranged in the developing container 20 to the upper right of the supply and conveyance screw 25b. A part of the outer peripheral surface of the developing roller 31 is exposed from the opening 20b of the developing container 20 and faces the photosensitive drum 1a. The developing roller 31 rotates counterclockwise in FIG.

The developing roller 31 includes a cylindrical developing sleeve that rotates counterclockwise in FIG. 2 and a developing roller side magnetic pole (not shown) fixed in the developing sleeve.

A regulation blade 35 is attached to the developing container 20 along the longitudinal direction of the developing roller 31 (direction perpendicular to the paper surface of FIG. 2). A slight gap is formed between the tip of the regulation blade 35 and the surface of the developing roller 31.

A DC voltage (hereinafter, also referred to as Vslv(DC)) and an AC voltage (hereinafter, also referred to as Vslv(AC)) are applied to the developing roller 31 by a developing bias power source (not shown).

As shown in FIG. 3, swing shafts 36 are provided at both ends in the longitudinal direction of the developing device 3a. As shown in FIGS. 4 and 5, the developing device 3a can be brought into contact with and separated from the photosensitive drum 1a by swinging about a swing shaft 36 (see FIG. 3). A developing pulley (not shown) that abuts the outer peripheral surface of the photosensitive drum 1a is provided at both ends of the rotating shaft of the developing roller 31, so that the developing device 3a is pressed by the photosensitive drum 1a. In the state of FIG. 4, a predetermined developing gap is formed between the developing roller 31 and the photosensitive drum 1a.

As described above, the developer is agitated by the agitating/conveying screw 25a and the feeding/conveying screw 25b, and is circulated in the agitating/conveying chamber 21 and the feeding/conveying chamber 22 in the developing container 20 so that the toner is charged, and by the feeding/conveying screw 25b. The developer is conveyed to the developing roller 31. Then, a magnetic brush (not shown) composed of a magnetic carrier and toner is formed on the developing roller 31, and the magnetic brush on the developing roller 31 is regulated in layer thickness by the regulating blade 35, and then the developing roller 31 and the photosensitive drum. It is transported to the area facing 1a. Since a predetermined bias (Vslv (DC) and Vslv (AC)) is applied to the developing roller 31, toner flies from the developing roller 31 to the photosensitive drum 1a due to the potential difference between the developing roller 31 and the photosensitive drum 1a. The electrostatic latent image on the photosensitive drum 1a is developed.

As shown in FIG. 2, the bottom surface portion (contact portion) 23 of the developing container 20 is made of metal such as aluminum, and the other portion of the developing container 20 is made of resin. As shown in FIGS. 2 and 6, the bottom surface portion 23 includes an upper portion 23a that constitutes part of the inner surfaces of the stirring and conveying chamber 21 and the supply and conveying chamber 22 and the partition wall 20a, and a lower portion 23b that constitutes the lower surface of the developing container 20. , With. The upper portion 23a and the lower portion 23b are integrally formed, and are formed by cutting an extruded member, for example.

The circulation tube 50 of the cooling unit 40 that cools the developing container 20 is pressed against the lower portion 23b of the bottom surface portion 23.

Specifically, as shown in FIGS. 7 to 9, the cooling unit 40 radiates the heat of the circulation tube 50 that is brought into pressure contact with the lower portion 23b (see FIG. 2) of the developing container 20 and the cooling liquid in the circulation tube 50. The radiator 60 (heat dissipation part), the pump 70 for circulating the cooling liquid in the circulation tube 50, and the tank 80 for containing the cooling liquid. The radiator 60 is provided with a fan 61 for air-cooling the cooling liquid flowing in the radiator 60.

The circulation tube 50 includes a first tube 51 that connects the pump 70 and the radiator 60, a second tube 52 that connects the radiator 60 and the tank 80, and a third tube 53 that connects the tank 80 and the pump 70. Is included.

As shown in FIGS. 2, 8 and 9, the first tube 51 is formed so as to pass through the bottom surface portion 23 of the developing container 20 of the developing devices 3a to 3d. The first tube 51 has a heat receiving portion 51 a that receives the heat of the developing container 20. The cooling liquid sent from the tank 80 by the pump 70 receives heat in the heat receiving portion 51 a of the first tube 51, is cooled by the radiator 60, and returns to the tank 80.

At least the heat receiving portion 51a of the first tube 51 (here, the entire first tube 51) is made of, for example, a silicone tube or a rubber tube containing a heat conductive material such as ceramic, and has elasticity and high thermal conductivity. The second tube 52 and the third tube 53 are formed of, for example, a rubber tube containing no heat conductive material or a metal or resin tube.

Here, as shown in FIGS. 4 and 5, the first tube 51 is configured to be able to come into contact with and separate from the developing container 20.

Specifically, below the first tube 51, a holding member 90 that holds the first tube 51, and by moving the holding member 90 in the vertical direction, the first tube 51 is brought into contact with and separated from the developing container 20. The contacting/separating mechanism 110 is provided.

As shown in FIG. 10, a pair of first recesses 91 that extend in the longitudinal direction of the developing container 20 and that position the heat receiving portion 51 a of the first tube 51 are formed on the upper surface of the holding member 90. A second recess 23 c is formed in the bottom surface portion 23 of the developing container 20 so as to face the first recess 91. The sum of the depth H91 of the first recess 91 and the depth H23c of the second recess 23c is formed smaller than the outer diameter D51 of the first tube 51. Therefore, as shown in FIG. 2, the first tube 51 is deformed into an oval shape in a state where the holding member 90 is pressed against the lower surface of the developing container 20, and the contact area between the first tube 51 and the developing container 20 is changed. Will increase.

Further, engaging pieces 92 having a U-shaped cross section extending in the longitudinal direction of the developing container 20 are provided at both ends of the holding member 90 in the lateral direction of the developing container 20 (horizontal direction in FIG. 2). As shown in FIGS. 2 and 6, engagement projections 23d that extend in the longitudinal direction and that engage with the engagement pieces 92 of the holding member 90 are formed at both ends in the lateral direction of the lower portion 23b of the bottom surface portion 23. There is. As a result, as shown in FIG. 5, it is possible to prevent the holding member 90 from dropping in a state where the upper surface of the holding member 90 is separated from the developing container 20 (a pressing member 111 described later is arranged at a separated position). You can

As shown in FIGS. 11 and 12, the contacting/separating mechanism 110 includes a pressing member 111 (see also FIG. 4), a rotating shaft 112, an input gear 113, a cover gear 114a, and an interlocking gear 115. There is. The contact/separation mechanism 110 and the opening/closing cover 114 described later are provided for each of the image forming units Pa to Pd.

As shown in FIG. 4, the pressing member 111 presses the holding member 90 against the developing container 20 to press the heat receiving portion 51 a of the first tube 51 against the developing container 20. As shown in FIGS. 11 and 12, the rotating shaft 112 is arranged along the longitudinal direction of the developing container 20. The pressing member 111 is fixed to both ends of the rotating shaft 112. The input gear 113 is fixed to one end of the rotary shaft 112.

The cover gear 114 a is provided on the rotating shaft of the opening/closing cover 114. The open/close cover 114 is provided on the front surface of the main body of the image forming apparatus 100 so as to be openable and closable, and enables replacement of the photosensitive drums 1a to 1d and the developing devices 3a to 3d. One or more (two in this case) interlocking gears 115 are provided, and the rotational force is transmitted from the cover gear 114a to the input gear 113.

Further, as shown in FIG. 4, the pressing member 111 is arranged on the fixed portion 111a fixed to the rotary shaft 112, the compression spring 111b housed in the fixed portion 111a, and the tip of the compression spring 111b to press the holding member 90. And a pressing piece 111c that operates. The pressing member 111 is selectively arranged at a pressing position (position in FIG. 4) that presses the holding member 90 and a separation position (position in FIG. 5) separated from the holding member 90 by the rotation of the rotating shaft 112. It The holding member 90 is in pressure contact with the bottom surface of the developing container 20, and the first tube 51 is in pressure contact with the bottom surface of the developing container 20 in a state where the pressing member 111 is arranged at the pressing position. On the other hand, as shown in FIG. 5, the holding member 90 is separated from the bottom surface of the developing container 20 and the first tube 51 is separated from the developing container 20 in a state where the pressing member 111 is arranged at the separated position.

As shown in FIGS. 11 and 12, the input gear 113, the cover gear 114a, and the interlocking gear 115 are helical gears, and extend in the direction perpendicular to the paper surface of FIG. 12 (the lateral direction of the developing container 20). The rotation of the cover gear 114a about the extending axis is transmitted to the input gear 113 as the rotation about the axis extending in the left-right direction (the longitudinal direction of the developing container 20) in FIG.

As shown in FIGS. 4 and 5, the developing device 3a is configured to approach the photoconductor drum 1a by the pressing force of the pressing member 111.

By opening the opening/closing cover 114, the cover gear 114a rotates in the clockwise direction of FIG. 12, and the pressing member 111 rotates in the counterclockwise direction (first direction) as shown in FIG. The pressure on the developing container 20 is released. At this time, the developing device 3a swings counterclockwise around the swing shaft 36 (see FIG. 3) due to its own weight, and is separated from the photoconductor drum 1a.

On the other hand, by closing the opening/closing cover 114, the cover gear 114a rotates counterclockwise in FIG. 12, and the pressing member 111 rotates clockwise (second direction) as shown in FIG. 90 is pressed, and the first tube 51 is pressed by the developing container 20. At this time, the developing device 3a approaches the photosensitive drum 1a by the pressing force of the pressing member 111.

In the present embodiment, as described above, the heat receiving portion 51a of the first tube 51 is pressed against the developing container 20 by the pressing member 111 of the contact/separation mechanism 110. Thereby, the heat of the developing container 20 is directly transferred to the first tube 51, so that the heat conduction efficiency from the developing container 20 to the first tube 51 can be improved. Therefore, the developing devices 3a to 3d can be cooled efficiently.

Further, the developing devices 3a to 3d are configured to approach the photoconductor drums 1a to 1d by the pressing force of the pressing member 111. Accordingly, it is not necessary to separately provide a pressing mechanism that presses the developing devices 3a to 3d against the photosensitive drums 1a to 1d, and thus it is possible to suppress an increase in the number of parts.

In addition, as described above, the first tube 51 has elasticity. Accordingly, the contact area between the first tube 51 and the developing container 20 can be increased in a state where the first tube 51 is pressed against the developing container 20, so that the heat transfer efficiency from the developing container 20 to the first tube 51 is high. Can be further improved. Therefore, the developing devices 3a to 3d can be cooled more efficiently.

Further, as described above, the first tube 51 is made of rubber containing a heat conductive material. Thereby, the heat conduction efficiency from the developing container 20 to the first tube 51 can be further improved, so that the developing devices 3a to 3d can be cooled more efficiently.

Further, as described above, the sum of the depth H91 of the first recess 91 of the holding member 90 and the depth H23c of the second recess 23c of the bottom surface portion 23 is smaller than the outer diameter D51 of the heat receiving portion 51a. Thereby, the contact area between the first tube 51 and the developing container 20 can be easily increased in a state where the first tube 51 is pressed against the developing container 20.

Further, as described above, the bottom surface portion 23 of the developing container 20 is made of metal. Thereby, the heat conduction efficiency from the developing container 20 to the first tube 51 can be further improved, so that the developing devices 3a to 3d can be cooled more efficiently.

Further, as described above, the first tube 51 is pressed against the bottom surface of the developing container 20. The temperature rise of the developing devices 3a to 3d is caused by frictional heat generated between the stirring and conveying member and the developer when the stirring and conveying members (the stirring and conveying screw 25a and the supply and conveying screw 25b) of the developing devices 3a to 3d are driven. The temperature at the bottom of the developing container 20 is likely to rise because the frictional heat is generated between the developers. Therefore, the developing devices 3a to 3d can be cooled more efficiently by pressing the first tube 51 against the bottom surface of the developing container 20.

Further, as described above, by opening the opening/closing cover 114, the cover gear 114a rotates, the pressing member 111 rotates in the first direction, the pressing of the first tube 51 against the developing container 20 is released, and the developing device is released. 3a to 3d are separated from the photosensitive drums 1a to 1d, the cover gear 114a is reversely rotated by closing the opening/closing cover 114, the pressing member 111 is rotated in the second direction, and the first tube 51 is developed by the pressing member 111. While being pressed by the container 20, the developing devices 3a to 3d approach the photoconductor drums 1a to 1d. Thus, by opening the opening/closing cover 114, the first tube 51 is separated from the developing devices 3a to 3d, and the developing devices 3a to 3d are separated from the photosensitive drums 1a to 1d. Therefore, the photoconductor drums 1a to 1d and the developing devices 3a to 3d can be easily replaced. Further, by closing the opening/closing cover 114, the first tube 51 can be automatically pressed against the developing container 20, and the developing devices 3a to 3d can be automatically brought close to the photosensitive drums 1a to 1d. ..

It should be considered that the embodiments disclosed this time are exemplifications in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

For example, although an example in which the present invention is applied to a color printer has been shown, the present invention is not limited to this. Needless to say, the present invention can be applied to various image forming apparatuses including a developing device, such as a monochrome printer, a monochrome copying machine, a digital multi-functional peripheral, and a facsimile.

Further, in the above embodiment, an example in which the first tube 51 is brought into pressure contact with the bottom surface of the developing container 20 has been described, but the present invention is not limited to this. For example, the first tube 51 may be brought into pressure contact with the side surface of the developing container 20 (the surface opposite to the photosensitive drums 1a to 1d, the left surface in FIG. 2).

Further, in the above-described embodiment, the example in which the holding member 90 is provided with the first recess 91 and the developing container 20 is provided with the second recess 23c has been described, but the present invention is not limited to this, and the holding member 90 is provided with the first recess. It is not necessary to provide the second concave portion 23c in the developing container 20 while providing 91. That is, the bottom surface of the developing container 20 may be formed flat.

1a to 1d Photoreceptor drum (image bearing member)
3a-3d Developing device 20 Developing container 23 Bottom part (pressed contact part)
23c 2nd recessed part 31 Developing roller 40 Cooling unit 50 Circulation tube 51a Heat receiving part 60 Radiator (heat dissipation part)
70 Pump 90 Holding Member 91 First Recess 100 Image Forming Device 110 Contact and Separation Mechanism 111 Pressing Member 112 Rotating Shaft 113 Input Gear 114 Open/Close Cover 114a Cover Gear D51 Outer Diameter H23c, H91 Depth

Claims (7)

An image carrier on which an electrostatic latent image is formed,
The static roller formed on the image carrier has a developing roller which is arranged to face the image carrier and supplies toner to the image carrier, and a developing container which stores a developer containing toner. A developing device for developing the latent image into a toner image,
A cooling unit for cooling the developing device;
A contact/separation mechanism for contacting and separating the circulation tube of the cooling unit with respect to the pressure-contacted portion of the developing device;
Equipped with
The cooling unit circulates the cooling liquid, the circulation tube having a heat receiving portion that is pressed against the development container to receive the heat of the developing container, the heat radiation portion that radiates the heat of the cooling liquid in the circulation tube. And a pump,
The contacting/separating mechanism has a pressing member that presses the heat receiving portion of the circulation tube against the developing container,
The image forming apparatus, wherein the developing device is configured to approach the image carrier by the pressing force of the pressing member. The image forming apparatus according to claim 1, wherein the heat receiving portion of the circulation tube has elasticity. The image forming apparatus according to claim 2, wherein the heat receiving portion of the circulation tube is formed of rubber containing a heat conductive material. Further comprising a holding member that is disposed between the pressing member and the heat receiving portion and that has a first concave portion that positions the heat receiving portion,
The pressed contact portion has a second concave portion that is arranged to face the first concave portion,
The image forming apparatus according to claim 2, wherein the sum of the depth of the first recess and the depth of the second recess is smaller than the outer diameter of the heat receiving unit. The image forming apparatus according to claim 1, wherein the pressed portion is made of metal. The image forming apparatus according to claim 1, wherein the pressed portion is provided on a bottom surface of the developing container. The contacting/separating mechanism includes the pressing member, a rotating shaft extending in the longitudinal direction of the developing device and to which the pressing member is fixed, an input gear fixed to one end of the rotating shaft, and an image forming apparatus main body. A cover gear which is provided on a rotating shaft of an opening/closing cover and which transmits a rotational force to the input gear,
The cover gear is rotated by opening the opening/closing cover, the pressing member is rotated in the first direction, the pressing of the circulation tube on the developing container is released, and the developing device is separated from the image carrier. Then
The cover gear rotates in the reverse direction by closing the opening/closing cover, the pressing member rotates in a second direction opposite to the first direction, and the circulation tube is pressed against the developing container by the pressing member, The image forming apparatus according to claim 1, wherein the developing device approaches the image carrier.

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