JP5645150B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.

  In an image forming apparatus, it is known that units such as a writing unit, a fixing unit, and a developing unit provided in the apparatus generate heat and raise the temperature in the apparatus.

  For example, in the developing unit, when a developer stirring / conveying member that stirs and conveys the developer in the developing unit is driven, frictional heat generated by the rubbing between the developer stirring / conveying member and the developer, or sliding between the developers. The temperature in the apparatus is raised by frictional heat due to rubbing. In addition, the friction heat generated by the friction between the developer regulating member and the developer that regulates the layer thickness of the developer carried on the developer carrying body before the developer is transported to the developing area, and the developer regulating member. The temperature in the apparatus is increased by frictional heat generated by rubbing between the developers during the regulation.

  When the temperature in the apparatus rises, the charge amount of the toner decreases, the toner adhesion amount increases, and a predetermined image density cannot be obtained. Further, the toner may melt due to the temperature rise and adhere to the developer regulating member, the developer carrier, the image carrier, etc., and a streaky abnormal image may be generated in the image. In particular, in recent years, when a toner having a low melting temperature is used in order to reduce the fixing energy, an abnormal image or the like due to the fixing of the toner tends to occur.

  Therefore, conventionally, outside air taken in by an air-cooling fan is conveyed to the periphery of the developing unit by a duct, and an air flow is generated to air-cool the developing unit, thereby suppressing the temperature of the developing unit from excessively rising. However, in recent years, due to the miniaturization of the image forming apparatus, the inside of the apparatus has been increased in density, and there is no room for space around the developing unit. For this reason, it is difficult to secure a space for installing a duct for conveying the airflow of the air cooling fan around the developing unit, and it is difficult to forcibly cool the developing unit.

  On the other hand, the intermediate transfer portion also has the following problems. The toner scraped off by the cleaning blade for cleaning the intermediate transfer belt is collected in a waste toner transport unit, and is merged with waste toner and the like that are no longer necessary in the image forming apparatus by the waste toner transport unit. If the belt cleaning unit is in the vicinity of the fixing unit and the effect of self-heating due to conveyance, the temperature becomes higher than the toner melting temperature when left unattended. For this reason, conventionally, outside air taken in by an air cooling fan is transported to the periphery of the intermediate transfer unit by a duct, and an air flow is generated to air-cool the intermediate transfer unit, thereby suppressing an excessive increase in the temperature of the intermediate transfer unit. ing. However, in recent years, due to the miniaturization of the image forming apparatus, the inside of the apparatus is increased in density and the space around the intermediate transfer unit has been reduced. For this reason, it is difficult to secure a space for installing a duct for conveying the air flow of the air cooling fan around the intermediate transfer unit, and it is difficult to forcibly cool the intermediate transfer unit. In addition, when an airflow is generated around by air cooling, a problem such as a dust problem such as toner occurs and the inside and outside of the machine is soiled.

  Patent Document 1 describes an image forming apparatus using a liquid cooling system that circulates liquid to cool a developing unit that is a heat generating unit. The liquid cooling device includes a heat receiving unit that contacts the developing unit wall surface that is a heat generating unit and receives the heat of the developing unit from the cooling liquid, a radiator that is a heat radiating unit for radiating the heat of the cooling liquid, and a cooling liquid that receives the heat of the developing unit. And a conveying pump as a conveying means for conveying the cooling liquid in the circulating pipe to the heat receiving part. Since the liquid cooling device can cool more efficiently than the air cooling device, the developing unit can be cooled efficiently. Further, since the circulation pipe for circulating the coolant is smaller than the duct, the circulation pipe can be arranged around the developing unit even if the space around the developing unit is narrow. Therefore, the developing unit can be cooled even if the density in the apparatus is increased.

  Further, the developing unit may be configured to be detachable from the apparatus main body as a single unit, or may be configured to be detachable from the apparatus main body integrally with the latent image carrier as a process cartridge. Further, it is known that the development gap between the latent image carrier and the developer carrier provided in the development unit has a great influence on the quality of the image. For this reason, positioning means is provided, and the developing unit is assembled by positioning the developing unit with respect to the latent image carrier with high accuracy.

  In the image forming apparatus described in Patent Document 1, when the developing unit is attached or detached, the heat receiving portion is separated from the developing unit, and when the developing unit is attached to the apparatus main body, the heat receiving portion is moved by the urging means. A contact / separation mechanism that is urged toward the developing unit and has a heat receiving portion in close contact with the developing unit is provided. With this configuration, the developing unit can be easily attached and detached. Further, when the developing unit is mounted, the heat receiving portion is in close contact with the developing unit, so that the developing unit can be efficiently cooled.

  However, in the image forming apparatus described in Patent Document 1, the heat receiving unit presses the developing unit by the urging force of the urging unit when the developing unit is set. As a result, a pressing force from the heat receiving portion is applied to the developing unit, and the pressing force applied to the developing unit acts on the positioning means and the like. As a result, there has been a problem that the positioning means and the like are deformed and the development gap fluctuates.

  Even when the liquid cooling method described in Patent Document 1 is used to cool the cleaning unit for the intermediate transfer belt, the distance between the cleaning blade for cleaning the surface of the intermediate transfer belt and the intermediate transfer belt varies. If there is, the cleaning of the intermediate transfer belt by the cleaning blade does not satisfy the function. For example, when the distance is longer than a specified value, the toner on the surface of the intermediate transfer belt cannot be scraped off by the cleaning blade, and the next transfer is performed while the surface of the intermediate transfer belt is dirty. For this reason, if the image becomes dirty or if the surface remains dirty, the dust may clog and cause the machine to stop. On the other hand, if the distance is shortened, the cleaning blade may flutter, which may cause damage to the cleaning blade or the intermediate transfer belt.

The present invention has been made in view of the above problems, and its purpose is to suppress problems such as fluctuations in the installation position of the cooled portion even if the heat receiving portion is pressed against the cooled portion where the temperature rises. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

In order to achieve the above-mentioned object, the invention of claim 1 is provided with a part to be cooled that is detachably attached to the main body of the image forming apparatus and a part to be in contact with the part to be cooled. An image forming apparatus comprising: a cooling device having a heat receiving portion that receives the heat of the cooled portion by flowing; and an contacting / separating mechanism that contacts and separates the heat receiving portion from the cooled portion. , the holding member for holding said heat receiving portion, and a guide portion for guiding the holding member in the direction in which the holding member is spaced apart the respect to the image forming apparatus main body and the take-out direction of the cooled parts from the object to be cooled It is characterized by having.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the guide portion is formed so that the heat receiving portion abuts on the cooled portion while sliding on the cooled portion. It is characterized by.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the guide portion is formed on a support member that supports the holding member so as to be able to contact and separate from the cooled portion. It is characterized by.
According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the holding member has an engagement pin, the support member engages with the engagement pin, and the engagement pin receives the engagement pin. It has an engagement hole which guides in the direction which contacts / separates with respect to a cooling part.
The invention of claim 5 is the image forming apparatus according to claim 1, 2, 3, or 4, wherein the cooled portion has a developer carrier for conveying the developer to a portion facing the latent image carrier. The developing unit is detachably attached to the main body of the image forming apparatus.

According to the present invention, even if the heat receiving portion is brought into pressure contact with the portion to be cooled whose temperature rises, problems such as a change in the installation position of the portion to be cooled can be suppressed .

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 6 is a front perspective view of a K-color image forming unit. FIG. 3 is a rear perspective view of a K-color image forming unit. The schematic block diagram which shows the structure which provided the metal roller in the both ends of the developing roller. The schematic block diagram of a liquid cooling device. The schematic block diagram of a heat receiving part. The figure which shows the 1st modification of a liquid cooling device. The figure which shows the 2nd modification of a liquid cooling device. The figure which shows the 3rd modification of a liquid cooling device. FIG. 2 is a schematic configuration diagram when the periphery of a K-color image forming unit is viewed from the front side of the apparatus. FIG. 3 is a cross-sectional view around a K color image forming unit. The perspective view which shows a holding member and a heat receiving part. The perspective view which shows a holding member. The figure which looked at the holding member and the heat receiving part from the near side. The figure which shows a mode that the engagement pin was crimped and fixed to the holding member. The perspective view which shows a heat receiving part. The perspective view which shows a supporting member. The schematic block diagram of an engagement hole. The perspective view which shows a fixing member and a supporting member. The perspective view which looked at the fixing member and the supporting member from another angle. FIG. 4 is a diagram illustrating a state where a heat receiving unit is in pressure contact with a developing unit. FIG. 6 is a diagram illustrating a state where a heat receiving unit is separated from a developing unit. The figure which shows the 1st modification of an engagement hole. The figure which shows the 2nd modification of an engagement hole. The figure which shows the structure which affixed the sheet | seat of the material of heat conductivity lower than a heat receiving part on the outer surface of a holding member. The figure which shows the structure which affixed the sheet | seat of the material of heat conductivity lower than a heat receiving part on the inner surface of a holding member. The figure which shows the structure which provided the magnet in the both ends of the supporting member and the holding member. The figure which shows the structure which provided the spacer in the both ends of the supporting member. FIG. 3 is a diagram illustrating an image forming apparatus in which an exposure device is below a development forming unit. The figure which shows the state which the heat receiving part press-contacts to the lower surface of the image development unit. The figure which shows the state from which the heat receiving part is spaced apart from the lower surface of the image development unit. The figure which shows the structure which fixes a support member via an elastic member. The figure explaining the position of a support member when an image forming unit is removed. The figure which shows the structure which cools all the development units with one heat receiving part. 1 is a diagram showing a direct transfer tandem color image forming apparatus. FIG. The figure which shows a mode that the engaging part and the to-be-engaged part engaged. FIG. 10 is a cross-sectional view of the periphery of a K-color image forming unit of an image forming apparatus according to Modification 2. Sectional drawing which shows the holding member and heat receiving part in the modification 2. FIG. The schematic perspective view which shows the 1st engaging part periphery of the modification 2. As shown in FIG. The schematic block diagram which shows the 2nd engaging part periphery of the modification 2. FIG. FIG. 10 is a diagram illustrating a state when a K-color image forming unit is removed from an image forming apparatus according to a second modification. FIG. 6 is a diagram illustrating a state in which a heat receiving unit is separated from a side surface of a developing unit. FIG. 10 is a perspective view of a holding member in an image forming apparatus according to Modification 3. FIG. 10 is a perspective view of a support member in an image forming apparatus according to Modification 3. The figure which shows the structure which provided the protrusion part in the back side surface of a developing unit. The figure which shows the structure which provided the protective layer in the back end part of the heat receiving part. FIG. 10 is a schematic diagram schematically showing an intermediate transfer belt cleaning unit and a liquid cooling device according to Modification 4.

  Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described. First, the configuration and operation of the image forming apparatus according to the present embodiment will be described.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. The image forming apparatus of FIG. 1 includes an image forming unit 1 in which four image forming units 11Y, 11M, 11C, and 11K are arranged in parallel. Drum-shaped photoconductors 18Y, 18M, 18C, and 18K as image carriers, drum cleaning units 12Y, M, C, and K, charging units 13Y, M, C, and K, two-component developing type developing units 19Y, M, and C , K, etc. are housed in a frame (not shown). These image forming units 11Y, 11M, 11C, and 11K are detachable from the printer main body, so that consumable parts can be replaced at a time.

  Above the image forming unit 1, an exposure unit 9 is provided as a latent image forming unit. In addition, a reading device 10 that scans and reads a document placed on a contact glass is provided at the top of the device. Below the image forming unit 1, a transfer unit 2 including an intermediate transfer belt 15 as an intermediate transfer member is provided. The intermediate transfer belt 15 is stretched around a plurality of support rollers, and rotates in the clockwise direction in the drawing. A secondary transfer device 4 is provided below the transfer unit 2. The secondary transfer device 4 includes a secondary transfer roller 17, and the secondary transfer roller 17 abuts on the intermediate transfer belt 15 where the intermediate transfer belt 15 is wound around the transfer counter roller 16 from the belt front surface and performs secondary transfer. A nip is formed. A secondary transfer bias is applied to the secondary transfer roller 17 by a power source (not shown). The transfer counter roller 16 is electrically grounded. Thereby, a secondary transfer electric field is formed in the secondary transfer nip. On the left side of the secondary transfer device 4 in the figure, a fixing unit 7 having a heating roller having a heating element therein is provided in order to fix the toner image transferred onto the paper. In addition, a conveyance belt 6 is provided between the secondary transfer device 4 and the fixing unit 7 to convey the sheet after transfer of the toner image to the fixing unit 7. A paper feed unit 3 is provided below the apparatus for feeding papers separated and fed one by one from a paper feed storage unit (not shown) to the secondary transfer device 4. In addition, a paper discharge unit 8 that transports the paper that has passed through the fixing unit 7 to the outside of the apparatus or to the duplex unit 5 is provided.

  When making a copy with this image forming apparatus, the reading apparatus 10 reads the document. In parallel with this document reading, the intermediate transfer belt 15 moves in the clockwise direction in the figure. At the same time, in the image forming unit 1, yellow, magenta, and magenta, based on the contents of the read original, are placed on the photoreceptors 18 Y, M, C, and K whose surfaces are charged by the charging units 13 Y, M, C, and K, respectively. A latent image is formed by exposure by the exposure unit 9 using cyan and black color-specific information. Next, the latent images on the photoconductors 18Y, 18M, 18C, and 18K are developed by the developing units 19Y, 19M, 19C, and 19K to form single-color toner images (developed images). Then, the toner images on the photoconductors 18Y, 18M, 18C, and 18K are sequentially transferred so as to overlap each other on the intermediate transfer belt 15 to form a composite toner image on the intermediate transfer belt 15. The photosensitive members 18Y, 18M, 18C, and 18K after the transfer of the toner image are removed by the drum cleaning units 12Y, 12M, 12C, and 12K to remove residual toner remaining on the photosensitive members 18Y, 18M, 18C, and 18K. Prepare for image formation.

  In parallel with the toner image formation, paper is fed out one by one from a paper feed storage unit (not shown), and abutted against the registration roller 14 and stopped. Then, the registration roller 14 is rotated in synchronization with the formation of the composite toner image on the intermediate transfer belt 15, the sheet is fed between the intermediate transfer belt 15 and the secondary transfer device 4, and transferred by the secondary transfer device 4. Then, the toner image is transferred onto the paper. The sheet on which the toner image has been transferred is conveyed by the conveying belt 6 and sent to the fixing unit 7. The fixing unit 7 applies heat and pressure to fix the toner image, and then the sheet is sent to the paper discharge unit 8. The paper discharge unit 8 is switched by a switching claw and guided to a paper discharge tray (not shown) outside the apparatus (on the left side of the apparatus) or the duplex unit 5 below. In the duplex unit 5, the sheet is reversed and guided again to the secondary transfer position (nip position between the secondary transfer device 4 and the intermediate transfer belt 15). Eject onto the output tray. The intermediate transfer belt 15 after image transfer is removed by the intermediate transfer belt cleaning unit 90 to remove the residual toner remaining on the intermediate transfer belt 15 and prepare for image formation again.

2 is a front perspective view of the K-color image forming unit 11K, and FIG. 3 is a rear perspective view of the K-color image forming unit 11K. 2 and 3, only the photosensitive member 18K and the developing unit 19K are shown.
The photoconductor 18K includes a phototube 18cK coated with a photoconductive layer, a front flange 18aK, and a back flange 18bK. The front side flange 18aK and the back side flange 18bK of the photoconductor 18K are rotatably supported by the frame 110K of the image forming unit 11K.
The developing unit 19K is temporarily positioned on the frame 110K of the image forming unit 11K, and then positioned by the front positioning plate 111K and the back positioning plate 112K as positioning means. These positioning plates 111K and 112K rotatably support a drum shaft 18dK which is a support shaft of the photosensitive member 18K and a developing roller shaft (not shown) of a developing roller 19aK which is a developer carrying member included in the developing unit 19K. A constant developing gap is maintained between the photoconductor 18K and the developing roller 19aK. That is, the drum shaft 18dK of the photosensitive member 18K is rotatably fitted to the positioning plates 111K and 112K via the bearings. The developing roller shaft of the developing roller 19aK is also rotatably fitted to the positioning plates 111K and 112K via bearings.
The rear positioning plate 112K is formed with a non-illustrated secondary reference hole made of a long hole, and a secondary reference pin 19bK fixed to the developing unit 19K is fitted into the secondary reference hole. Similarly, a secondary reference hole (not shown) made of a long hole is formed in the front positioning plate 111K, and a secondary reference pin 19bK fixed to the developing unit 19K is fitted in the secondary reference hole. Thus, the developing unit 19K is prohibited from rotating around the central axis of the developing roller 19aK by fitting the sub-reference pin 19bK into a non-illustrated sub-reference hole formed in each positioning plate 111K, 112K. Is done.

An opening for attaching and detaching the image forming unit 11K is provided on a side surface of the image forming apparatus main body.
When the image forming unit 11K is mounted, the drum shaft 18dK extending from the photoconductor motor 30K passes through the photoconductor 18K and is fitted to the bearings of the positioning plates 111K and 112K. As a result, the photosensitive member 18K is positioned, and the distance between the central axis of the photosensitive member 18K and the central axis of the developing roller 19aK is correctly regulated. Thus, the minute gap between the photoconductor 18K and the developing roller 19aK is correctly maintained, and a high-quality toner image can be developed on the photoconductor 18K. The positioning plates 111K and 112K are preferably made of resin in terms of cost and weight, but may be made of metal.
Further, as shown in FIG. 4, metal rollers 190 are provided at both ends of the developing roller 19aK, and these metal rollers 190 are brought into contact with the flanges 18aK and 18bK of the photosensitive member, so that the developing roller 19aK and the photosensitive member 18K are in a predetermined state. You may make it position so that it may become a development gap.

  Here, in the image forming apparatus, from the viewpoint of reducing the size of the machine, the arrangement is such that the fixing unit 7 is pulled down to the lower side of the transfer unit 2 together with the higher density inside the machine. In the image forming apparatus of FIG. 1, the intermediate transfer belt 15 is bent so as to cover the upper surface and the right side surface of the fixing unit 7. With this configuration, the height direction and width direction of the apparatus are made compact.

  However, if the fixing unit 7 is brought close to the intermediate transfer belt 15, the intermediate transfer belt 15 may be deformed due to thermal influence by the fixing unit 7 serving as a heating element, and image defects such as color misregistration may occur. . This has become more prominent due to an increase in the amount of heat generated inside the apparatus as the speed of the apparatus increases. Further, during double-sided printing, the paper heated by the fixing unit 7 passes through the double-sided unit 5 and again comes into contact with the intermediate transfer belt 15 at the secondary transfer position, so that the intermediate transfer belt is further transferred by heat transfer from the paper. The temperature of 15 rises and becomes a more severe condition. In addition, heat is transmitted to the photosensitive members 18Y, 18M, 18C, and 18K that are in contact with the intermediate transfer belt 15, and further to the developing units 19Y, 19M, 19C, and 19K, image defects due to belt deformation, toner solidification, and the like. Problems are more likely to occur.

  Therefore, a heat insulating device 20 is provided between the fixing unit 7 that is a heat source and the intermediate transfer belt 15 that is disposed in the vicinity of the fixing unit 7. Although the heat insulating device 20 is often composed of an air flow by a duct, here, a heat insulating device using a heat pipe will be described. This is mainly composed of a heat receiving plate 21, a heat pipe 22, a heat radiating plate 23, a duct 24 and an exhaust fan (not shown). The heat receiving plate 21 that is a heat receiving member is formed of a material that easily absorbs heat, and is disposed between the fixing unit 7 that is a heat generation source and the transfer unit 2 that is a protection target portion to be protected from the influence of the heat. . The heat pipe 22 as a heat transfer means (heat transport means) is attached to the lower surface of the heat receiving plate 21, and one end portion (lower end portion) side thereof is a heat receiving portion. The other end side of the heat pipe 22 is a heat radiating portion, and is mounted on the heat radiating plate 23 at a position higher than the heat receiving portion. The heat radiating plate 23 that is a heat radiating member is formed of a material that easily releases heat, and a heat sink may be provided as necessary. In this example, the duct 24 extends from the front surface to the back surface of the image forming apparatus main body, and is provided so that the heat radiating plate 23 is positioned inside the duct. An air inflow port is provided at the front side end of the duct 24, an exhaust port is provided at the back side end, and an exhaust fan (not shown) is provided at the exhaust port. The heat insulating device 20 configured as described above receives heat from the heat generating portion (the fixing unit 7 in this example) by the heat receiving plate 21, and the heat is transferred to the heat radiating portion (heat radiating plate 23) by the heat pipe 22 serving as heat transfer means. Transported up to. Then, heat is released from the heat radiating plate 23 in the duct 24, and the released heat is discharged outside the apparatus by an exhaust fan (not shown). Note that it is possible to perform natural cooling without providing an exhaust fan. In this way, the influence of the fixing heat is cut off, and the image forming units 11Y, 11M, 11C, and 11K, and the transfer unit 2 that are the protection targets are effectively protected, thereby preventing color misregistration due to deformation of the intermediate transfer belt 15 and the like. The occurrence of troubles and troubles due to toner solidification is prevented in advance.

  Further, in the developing units 19Y, 19M, 19C, and 19K, when the developer stirring and conveying member that stirs and conveys the developer in the developing unit is driven, frictional heat due to friction between the developer stirring and conveying member and the developer is driven. In addition, the temperature in the developing unit is raised by frictional heat due to rubbing between the developers. In addition, the friction heat generated by the friction between the developer regulating member and the developer that regulates the layer thickness of the developer carried on the developer carrying body before the developer is transported to the developing area, and the developer regulating member. The temperature inside the developing unit is raised by frictional heat caused by rubbing between the developers at the time of regulation.

  When the temperature in the developing unit rises, the charge amount of the toner decreases, the toner adhesion amount increases, and a predetermined image density cannot be obtained. Further, the toner may melt due to the temperature rise and adhere to the developer regulating member, the developer carrying member, the photosensitive member, etc., and a streaky abnormal image may be generated in the image. In recent years, when a toner having a low melting temperature is used in order to reduce the fixing energy, an abnormal image or the like is likely to occur due to toner fixation. In addition, the development unit tends to become hot due to the increase in printing speed.

  Therefore, the developing units 19Y, 19M, 19C, and 19K are extremely important cooling parts for achieving high image quality and high reliability. Conventionally, an air flow is generated around the developing unit by an air cooling fan or the like to cool the developing units 19Y, 19M, 19C, 19K, which are the temperature rise points, and the temperatures of the developing units 19Y, 19M, 19C, 19K rise excessively. Is suppressed. However, with the demand for miniaturization, it is necessary to reduce the duct for forming the flow path around the developing unit. When the duct becomes small, the flow rate of gas flowing into the periphery of the developing unit decreases, and the developing unit cannot be sufficiently cooled.

  For this reason, in the image forming apparatus of the present embodiment, the developing units 19Y, M, C, and K are cooled by the liquid cooling device.

FIG. 5 is a schematic configuration diagram of the liquid cooling device 30.
As shown in the figure, the liquid cooling device 30 is in pressure contact with the wall surfaces of the developing units 19Y, M, C, and K, which are portions where the temperature has risen, and the four heat receiving portions 32Y, 32, C, K, three cooling means 35 for cooling the cooling liquid, a circulation pipe 34 that contains the cooling liquid, a cooling pump 31 that is a conveying means for circulating the cooling liquid in the circulation pipe, and excess cooling liquid A reserve tank 33 for storage is provided. Each cooling unit 35 includes a radiator 35b, a cooling fan 35a, and the like serving as heat dissipation means.

  FIG. 6 is a schematic configuration diagram of the heat receiving portion 32K. The other heat receiving portions 32Y, 32M, 32C have the same configuration. The heat receiving portion 32K is provided with a flow path 32bK formed of a member having high thermal conductivity in a case 32aK formed of a member having high thermal conductivity. Usually, the case 32aK and the flow path 32bK of the heat receiving portion 32K are configured based on copper having a thermal conductivity of about 400 [W / mK] or aluminum of about 200 [W / mK]. Further, a material having higher thermal conductivity (for example, silver or gold) may be used. A circulation pipe 34 made of a flexible member such as a rubber tube or a resin tube is connected to the tip of the flow path 32bK. Although the details will be described later, the heat receiving portion 32K is supported by a contact / separation mechanism described later so as to be movable in the attaching / detaching direction of the image forming unit 11K. Therefore, if the circulation pipe 34 is made of a flexible member such as a rubber tube or a resin tube, the circulation pipe 34 can follow the movement of the heat receiving portion 32K, and the circulation pipe 34 is detached from the flow path 32bK. It is possible to suppress the occurrence of problems such as However, this does not necessarily mean that a rubber tube is necessary in the entire system, and a part of the circulation pipe 34 may be a metal pipe, which is more convenient because moisture permeability can be suppressed as much as possible.

  In addition, since the side surface of the developing unit 19K is made of a material having high thermal conductivity such as aluminum or copper, when the heat receiving portion 32K is brought into close contact with the side surface of the developing unit 19K, an air layer is formed. End up. If an air layer is formed, the efficiency of heat exchange falls. Therefore, in the present embodiment, the heat conductive sheet 130K is attached to a surface (hereinafter referred to as a pressure contact surface) facing the developing unit 19K of the heat receiving unit 32K (see FIG. 10). The heat conductive sheet 130K is required to have high heat conductivity, and at the same time, hardness (easiness to deform) that can crush the surface accuracy between the developing unit 19K and the heat receiving portion 32K. However, since the heat conductive sheet 130K has a property that it is hard when it has high heat conductivity and is soft when it has low heat conductivity, the heat conductive sheet 130K becomes hard to some extent in order to obtain high heat conductivity. Therefore, in this embodiment, the heat receiving portion 32K is pressed with a large pressing force so that the heat receiving portion 32K is pressed against the side surface of the developing unit 19K. Thereby, even if a heat conductive sheet that is hard to some extent is used, the heat conductive sheet 130K is deformed, and the surface accuracy between the developing unit 19K and the heat receiving portion 32K is crushed. Thereby, it is possible to suppress the formation of an air layer between the developing unit 19K and the heat receiving unit 32K, and to conduct heat of the developing unit 19K to the heat receiving unit satisfactorily. The heat conductive sheet 130K may be attached to the side surface of the developing unit.

  As shown in FIG. 5, in each cooling unit 35, heat dissipation is performed to transfer and dissipate the coolant through a housing (contained of aluminum having high thermal conductivity) that contains the cooling medium from the circulation pipe 34. A radiator 35b as means is provided, and forced air cooling or natural air cooling is performed by the cooling fan 35a according to the amount of heat radiation. Moreover, the cooling part 35 may be one and may be four or more. Moreover, although the cooling fan is provided for every cooling part, you may comprise so that external air may be supplied to the radiator of each cooling part with one cooling fan. By providing a plurality of cooling units 35, even if the cooling efficiency of each cooling unit is low, the temperature rise of all the developing units 19Y, 19M, 19C, and 19K can be satisfactorily suppressed. As a result, it is possible to use a small radiator that has a small heat dissipation area and a cooling efficiency that is not so high as compared with one that suppresses the temperature rise of all the developing units 19Y, 19M, 19C, and 19K in one cooling unit. It is possible to reduce the size of the part.

  The cooling pump 31 is a drive source that circulates the coolant through the heat receiving units 32Y, 32M, 32C, and 32K and the cooling unit 35, and circulates the coolant as shown by arrows in FIG. The reserve tank 33 is a tank for storing a coolant. The cooling liquid is a heat transport medium that transports the heat received by the heat receiving portions 32Y, 32M, 32C, and 32K to the radiator 35b. The coolant is mainly composed of water, and propylene glycol or ethylene glycol is added to lower the freezing temperature. In order to prevent rusting of metal components, a rust inhibitor (for example, phosphate-based substances: potassium phosphate salt, inorganic potassium salt, etc.) is added and used. When the coolant is water, the constant heat capacity is 3000 times or more that of air, and a large amount of heat can be transferred with a small flow rate, so that cooling can be performed more efficiently than forced air cooling.

  The cooling liquid cooled by the radiator 35b is sequentially sent from the heat receiving portion 32Y to C, M, and K, and then sent to the reserve tank 33 and the cooling pump 31, and then returned to the radiator 35b again. This is not the case. For example, as shown in FIG. 7, the heat receiving portions 32Y, 32M, 32C, 32K may be connected in parallel. Furthermore, as shown in FIG. 8, four cooling units are provided, each cooling unit is associated with each developing unit, and the cooling liquid cooled by the cooling unit is applied to the heat receiving unit provided in the corresponding developing unit. The circulation pipe 34 may be configured so that it does not flow to the heat receiving portion provided in the developing unit that does not correspond until it flows. Further, as shown in FIG. 9, a first liquid cooling device 30a for cooling the Y developing unit 19Y and the M developing unit 19M, a C developing unit 19C, and a K developing unit 19K. A second liquid cooling device 30b for cooling may be provided, and each developing unit may be cooled using two cooling devices. The configuration of the cooling device is determined by the amount of heat to be cooled by the heat receiving unit and the temperature condition, that is, the thermal design condition.

Next, a contact / separation mechanism that contacts and separates the heat receiving portion with respect to the developing unit will be described. In addition, since the structure of each contact / separation mechanism is the same, below, the contact / separation mechanism which contacts / separates the K color heat receiving part 32K is demonstrated as a representative.
In order not to reduce the cooling efficiency of the developing unit 19K, it is necessary to press the heat receiving portion 32K against the side surface of the developing unit 19K. Therefore, a large pressing force is applied to the developing unit 19K, and the pressing force applied to the developing unit 19K from the heat receiving portion 32K reaches the positioning plates 111K, 112K and the like. As a result, the positioning plates 111K and 112K may be deformed. When the positioning plates 111K and 112K are deformed, the development gap also changes. The error range of the development gap is very severe, and even if the positioning plates 111K and 112K are slightly deformed and the development gap is slightly varied, the image may be affected. However, if the pressing force of the heat receiving portion 32K against the developing unit 19K is weakened, the heat receiving portion 32K cannot be brought into close contact with the developing unit 19K, and the cooling efficiency of the developing unit 19K is reduced. Therefore, in this embodiment, when the heat receiving portion 32K is pressed against the developing unit 19K, the contact / separation mechanism and the developing unit 19K are engaged and fixed, and the pressing force of the heat receiving portion 32K on the wall surface of the developing unit 19K is increased. By avoiding external force, the pressing force from the heat receiving portion 32K is reduced from reaching the positioning plates 111K and 112K from the developing unit 19K. Specific description will be given below.

FIG. 10 is a schematic configuration diagram of the periphery of the K-color image forming unit 11K as viewed from the front side of the apparatus. FIG. 11 is a cross-sectional view of the periphery of the K-color image forming unit.
As shown in the figure, the apparatus body is provided with rails 62a and 62b (for example, an Acculide, etc.) that contract. The image forming unit 11K is attached to the rails 62a and 62b and the drum shaft 18dK, and the image forming unit 11K is pushed into the apparatus main body, whereby the image forming unit 11K is attached to the apparatus main body.
As shown in FIG. 10, on the developing unit side, a contact / separation mechanism 40K for contacting and separating the heat receiving portion 32K with respect to the developing unit 19K is provided.
The contact / separation mechanism 40K includes a holding member 41K that is a holding unit that holds the heat receiving portion 32K, and a support member 42K that is a support unit that supports the holding member 41K so as to be able to contact and separate from the developing unit 19K. The support member 42K is fixed to a fixing member 50K to which the left rail 62a in the drawing is attached. The fixing member 50 </ b> K is fixed to a partition plate 61 that partitions the writing area in which the exposure unit 9 is disposed from the image forming unit 1.
As shown in FIG. 10, the holding member 41 </ b> K faces the three surfaces of the heat receiving portion 32 </ b> K opposite to the pressure contact surface, the upper surface and the lower surface, and covers the heat receiving portion 32 </ b> K. In this way, by covering the heat receiving portion 32K with the holding member 41K, infrared light from the fixing unit or the like can be shielded, and the heat receiving portion 32K is prevented from being thermally influenced by other than the developing unit 19K. Can do. Thereby, it is possible to suppress the heat receiving portion 32K from being heated under the influence of heat from other than the developing unit 19K, and to efficiently cool the developing unit 19K.

FIG. 12 is a perspective view showing the holding member 41K and the heat receiving portion 32K, and FIG. 13 is a perspective view showing the holding member 41K. FIG. 14 is a view of the holding member 41K and the heat receiving portion 32K as viewed from the front side.
As shown in FIG. 13, the holding member 41K is formed by bending a sheet metal or the like, and is substantially equal in the longitudinal direction to the facing portion 41aK facing the surface opposite to the pressure contact surface of the heat receiving portion 32K. Holes 41bK are provided at five intervals. An engagement hole 41eK is provided at the center in the longitudinal direction of the first bent portion 41cK and the second bent portion 41dK (see FIG. 14) formed by bending from both ends in the short direction of the opposing portion 41aK of the holding member 41K. It has been. As shown in FIG. 15, an engagement pin 140K is fixed to the engagement holes 41eK by caulking.

As shown in FIG. 16, the heat receiving portion 32K is formed with five round grooves 32cK so as to correspond to the five holes 41bK provided in the facing portion 41aK of the holding member 41K. A screw hole 32dK is provided in the center of the bottom surface of each circular groove 32cK (see FIGS. 6 and 14). As shown in FIG. 14, a step screw 141K is loosely fitted in the five holes 41bK provided in the facing portion 41aK of the holding member 41K, and the screw portion of the step screw 141K is inserted into the screw hole 32dK of the heat receiving portion 32K. Screwed. A coil spring 142K, which is an elastic member, is wound around the step portion of the step screw 141K. One end of the coil spring 142K is in contact with the facing portion 41aK of the holding member 41K, and the other end is in contact with the bottom 32eK of the round groove that is an elastic member contact portion. Accordingly, the heat receiving portion 32K is urged toward the developing unit 19K by the coil spring 142K and is held by the holding member 41K. Further, as shown in FIG. 14, the heat receiving portion 32K is held by the holding member 41K with a predetermined gap between the surface opposite to the pressure contact surface of the heat receiving portion 32K and the facing portion 41aK. As a result, when the heat receiving portion 32K hits the side surface of the developing unit 19K, the heat receiving portion 32K can be moved relative to the holding member 41K, and the heat receiving portion 32K can be in good pressure contact with the developing unit 19K. Can do. As shown in FIG. 14, the heat receiving portion 32K is held such that the pressure contact surface of the heat receiving portion 32K protrudes beyond the tips of the first and second bent portions 41cK and 41dK of the holding member 41K. Thereby, it is possible to prevent the tips of the first and second bent portions 41cK and 41dK of the holding member 41K from hitting the developing unit 19K when the heat receiving portion 32K is brought into contact with the developing unit 19K.
Further, by changing the type of the coil spring 142K that is an elastic member, the pressing force of the heat receiving portion 32K on the developing unit 19K can be easily changed.
Further, a round groove 32cK is formed in the heat receiving portion 32K, the bottom of the round groove 32cK is used as an elastic member abutting portion 32eK of the heat receiving portion, and the elastic member abutting portion 32eK of the heat receiving portion 32K is located on the side opposite to the pressure contact surface. It is recessed to the development unit side. Accordingly, the distance between the facing portion 41aK of the holding member 41K and the elastic member contact portion 32eK can be made larger than the distance between the facing portion 41aK and the surface opposite to the pressure contact surface of the heat receiving portion 32K. Thereby, the fluctuation | variation of the pressing force of the coil spring 142K by the fluctuation | variation of the length of the coil spring 142K etc. can be decreased. Further, since the distance between the facing portion 41aK and the pressure contact surface of the heat receiving portion 32K and the surface on the opposite side can be reduced, the apparatus can be made compact.
In the present embodiment, the heat receiving portion 32K is elastically held at equal intervals in the longitudinal direction, so that a uniform pressing force can be generated in the heat receiving portion 32K.

  In the present embodiment, as shown in FIG. 13, the holes 41bK provided in the facing portion 41aK of the holding member 41K are arranged in a line in the longitudinal direction, but the holes 41bK may be arranged in a staggered manner. . In the present embodiment, the heat receiving portion 32K is elastically held at five locations. However, the heat receiving portion 32K is not limited to this, and the heat receiving portion 32K can be used as long as the pressure can be uniformly applied to the developing unit 19K over the entire surface of the heat receiving portion 32K. It does not matter how many places you hold the elastic. In addition, when the distance between the facing portion 41aK and the surface opposite to the pressure contact surface of the heat receiving portion 32K is sufficient, the circular groove 32cK may not be dug in the heat receiving portion 32K. In this embodiment, the elastic member for applying the pressing force is the coil spring 142K. However, a plate spring may be used, and a sponge for restoring the elastic force may be used. In the case of a sponge or the like, it may not be held by the stepped screw 141K. The sponge is joined to both the heat receiving part 32K and the holding member 41K with an adhesive or the like, and the heat receiving part 32K is held to the holding member 41K by the sponge. May be.

FIG. 17 is a perspective view of the support member 42K. The support member 42K includes a first member 421K and a second member 422K, and the first member 421K includes a back surface portion 421aK, a support portion 421bK, and a fixing portion 421cK. The first member 421K is formed by bending a sheet metal or the like. The first member 421K is formed by bending the vicinity of the end in the short direction of the back surface portion 421aK to form a support portion 421bK and a fixing portion 421cK. Yes. Attachment portions 421dK are provided in the vicinity of both ends in the longitudinal direction of the support portion 421bK, and an elongated hole 421eK is formed in the approximate center of these attachment portions 421dK. Screw holes are formed near both ends in the longitudinal direction of the fixing portion 421cK of the first member 421K, and the second member 422K is screwed to the first member 421K. An engagement hole 423K that engages with the engagement pin 140K of the holding member 41K is formed in the longitudinal center of the support portion 421bK of the first member 421K and the longitudinal center of the second member 422K. As shown in FIG. 18, the engagement hole 423K includes a guide portion 423aK inclined by 45 ° with respect to the longitudinal direction (developing unit insertion direction), and a locking portion 423bK extending in parallel with the longitudinal direction (developing unit insertion direction). have.
After engaging the engaging pin 140K that is caulked and fixed in the hole of the first bent portion 41cK of the holding member 41K with the engaging hole 423K of the support portion 421bK, the holding member 41K is inserted into the engaging hole 423K of the second member 422K. The engaging pin 140K that is caulked and fixed to the hole of the second bent portion 41dK is engaged. Then, the second member 422K is screwed to the fixing portion 421cK of the first member 421K. Thereby, the holding member 41K is supported by the support member 42K.
In the present embodiment, as shown in FIG. 11, the support portion 421bK of the first member 421K is the upper surface, but the support portion 421bK of the first member 421K may be the lower surface. The second member 422K is screwed to the fixing portion 421cK of the first member 421K, but may be fixed by rivets or welding. However, considering the maintainability of the heat receiving portion 32K, it is better that the first member 421K and the second member 422K can be easily divided by fixing with screws or the like.

Further, as shown in FIG. 17, a first engagement portion 161K extending in the longitudinal direction and bent upward is provided at the tip of the support portion 421bK of the first member 421K, and the tip of the second member 422K. Is provided with a second engaging portion 162K extending in the longitudinal direction and bent upward.
Further, as shown in FIG. 11, a first engaged portion 191K including a portion protruding from the side surface and a portion extending downward from the tip of the protruding portion is provided on the side surface of the developing unit 19K in the longitudinal direction of the developing unit. It has been. Further, a second engaged portion 192K protruding from the lower surface is provided in the end of the developing unit 19K in the longitudinal direction of the developing unit at the end of the lower surface of the developing unit 19K. The first engaging portion 161K is provided closer to the photoreceptor 18K than the first engaged portion 191K, and the first engaging portion 161K and the first engaged portion 191K are opposed to each other. The second engaging portion 162K is provided closer to the photoconductor 18K than the second engaged portion 192K, and faces the second engaged portion 192K.

  As shown in FIG. 19, the support member 42 </ b> K is fixed to a fixing member 50 </ b> K that is screwed to three locations of the partition plate 61. Specifically, a step screw 150K is loosely fitted into the elongated hole 421eK of the attachment portion 421dK of the support member 42K, and as shown in FIG. 20, the support member fixing base 51K provided near both longitudinal ends of the fixing member 50K. The screw portion of the stepped screw 150K is screwed into a screw hole (not shown) provided at a substantially central portion. Further, the support member 42K is fixed to the fixing member 50 so that a gap is generated between the back surface portion 421aK of the support member 42K and the fixing member 50K. Accordingly, the support member 42K is fixed to the fixing member 50K so as to be swingable in parallel with the pressing direction of the coil spring 142K. Thus, since the support member 42K can swing in parallel with the pressing direction of the coil spring 142K, as will be described later, the engaging portions 161K and 162K and the engaged portions 191K and 192K are attached when the developing unit is attached / detached. And the developing unit 19K can be attached and detached smoothly. Further, as will be described later, when the coil spring 142K presses the developing unit 19K via the heat receiving portion 32K, the support member 42K moves away from the developing unit 19K due to the reaction force from the developing unit 19K. be able to. As a result, the engaging portions 161K, 162K and the engaged portions 191K, 192K are engaged, and the contact / separation mechanism 40K can be fixed to the developing unit 19K.

Next, the contact / separation of the heat receiving portion 32K by the contact / separation mechanism 40K will be described.
FIG. 21 is a diagram illustrating a state in which the heat receiving unit 32K is in pressure contact with the developing unit 19K, and FIG. 22 is a diagram illustrating a state in which the heat receiving unit 32K is separated from the developing unit 19K.
When taking out the image forming unit 11K from the apparatus main body, if a lever (not shown) provided on the front side of the apparatus is operated, the holding member 41K is moved to the front side of the apparatus. When the holding member 41K moves to the front side of the apparatus, the engaging pin 140K of the holding member 41K moves from the locking portion 423bK of the engaging hole 423K to the guide portion 423aK. When the engaging pin 140K moves to the guide portion 423aK, the engaging pin 140K of the holding member 41K is guided to the guide portion 423aK of the engaging hole 423K, and the holding member 41K is moved relative to the support member 42K from the developing unit 19K. Move in the direction of separation. As a result, the heat receiving portion 32K held by the holding member 41K is separated from the developing unit 19K. When the engaging pin 140K hits the end of the guide portion 423aK, the heat receiving portion 32K is completely separated from the developing unit 19K as shown in FIG. When the heat receiving portion 32K is separated from the developing unit 19K, the image forming unit 11K is pulled out from the apparatus main body. As described above, when the image forming unit 11K is pulled out from the apparatus main body, the heat receiving portion 32K is separated from the developing unit 19K, and the pressing force from the heat receiving portion 32K is not applied to the developing unit 19K. Further, the engagement between the engaging portions 161K and 162K and the engaged portions 191K and 192K is released, and the engaging portion and the engaged portion are relatively movable in the developing unit attaching / detaching direction. As a result, the image forming unit 11K can be easily pulled out from the apparatus main body. Further, when the image forming unit 11K is taken out, the heat conductive sheet 130K and the developing unit 19K are prevented from rubbing. Therefore, it can suppress that the heat conductive sheet 130K is damaged.

  When the image forming unit 11K is attached to the apparatus main body, for example, by replacing the image forming unit 11K, the holding member 41K is moved to the back side of the apparatus by operating a lever (not shown). When the holding member 41K is moved to the back side of the apparatus, the engaging pin 140K of the holding member 41K is guided by the guide portion 423aK of the engaging hole 423K, and the holding member 41K moves to the developing unit side. As a result, the heat receiving portion 32K held by the holding member 41K moves to the developing unit side. Further, when the holding member 41K is moved to the back side of the apparatus, as shown in FIG. 36, the engaging pin 140K of the holding member 41K is guided by the guide portion 423aK, and the heat receiving portion 32K contacts the side surface of the developing unit 19K. Touch. When the holding member 41K is further moved to the rear side of the apparatus from this state, the heat receiving portion 32K presses the developing unit 19K while sliding with the side surface of the developing unit. At this time, when the engaged portions 191K and 192K of the developing unit 19K are not in contact with the engaging portions 161K and 162K of the contact / separation mechanism 40K, the reaction force from the developing unit is retained from the heat receiving portion 32K. It is transmitted to the support member 42K via the engagement pin 140K of the member 41K, and the support member 42K is pushed in a direction away from the developing unit 19K. Since the support member 42K is fixed to the fixing member 50K so as to be movable in a direction parallel to the pressing direction of the coil spring 142K, the support member 42K receives a reaction force from the developing unit 19K and is indicated by an arrow in FIG. As described above, the support member 42K moves in a direction away from the developing unit 19K. As a result, the engaged portions 191K and 192K of the developing unit 19K and the engaging portions 161K and 162K of the contact / separation mechanism come into contact with each other, and the engaging portion and the engaged portion are engaged. When the holding member 41K is further moved to the rear side of the apparatus from this state, the coil spring 142K is compressed because the support member 42K does not move in the direction away from the developing unit 19K even when the reaction force from the developing unit 19K is received. The heat receiving portion 32K is pressed against the wall surface of the developing unit 19K by the coil spring 142K. At this time, the holding member 41K receives the reaction of the pressing force applied from the heat receiving portion 32K to the coil spring 142K, and the reaction received by the holding member 41K is received by the support member 42K via the engagement pin 140K. That is, the holding member 41K and the support member 42K function as receiving means that receives the reaction of the pressing force. Since the engaging portions 161K and 162K of the support member 42K abut the engaged portions 191K and 192K, the reaction received by the support member 42K reaches the engaged portions 191K and 192K of the developing unit 19K. That is, the engaging portions 161K and 162K are engaged with the engaged portions 191K and 192K, so that the contact / separation mechanism 40K is fixed to the development unit 19K, and the development unit 19K and the contact / separation mechanism 40K are connected in the apparatus. Becomes like one. Accordingly, the pressing force by which the heat receiving portion 32K pushes the wall surface of the developing unit 19K can be applied as an internal force within the developing unit 19K without acting on the developing unit 19K as an external force. As a result, the force received by the positioning plates 111K and 112K from the developing unit 19K (due to the pressing force from the heat receiving portion 32K) can be reduced. Thereby, it can suppress that the positioning plates 111K and 112K etc. deform | transform. In addition, since deformation of the positioning plates 111K and 112K can be suppressed, fluctuations in the development gap can be suppressed, and high-quality images can be maintained over time. When the engaging pin 140K of the holding member 41K is guided to the engaging portion 423bK of the engaging hole 423K, the heat receiving portion 32K can press the developing unit 19K with a predetermined pressing force.

As shown in FIG. 18, in the present embodiment, the inclination angle of the guide portion 423aK of the engagement hole 423K is 45 °, but it may not be 45 °. If the angle is made smaller than 45 °, a force for pushing the holding member 41K when the holding member 41K is moved from the front side of the apparatus to the back side of the apparatus can be reduced. Conversely, if the inclination angle is larger than 45 °, when the engagement pin 140K of the holding member 41K is guided to the guide portion 423aK of the engagement hole 423K to contact and separate the heat receiving portion 32K, the heat conduction sheet 130K The rubbing area with the side surface of the developing unit 19K can be reduced, and the thermal conductive sheet 130K can be prevented from being damaged.
Further, as shown in FIG. 23, the engaging hole locking portion 423bK may be slightly inclined so as to approach the developing unit side as it goes to the back side of the apparatus. By doing so, it is possible to reduce the sliding area between the heat conductive sheet 130K and the side surface of the developing unit 19K when the heat receiving portion 32K is contacted and separated, and it is possible to suppress damage to the heat conductive sheet 130K. . However, in this case, due to the reaction from the developing unit 19K, the engaging pin 140K of the holding member 41K moves from the front end of the locking portion 423bK to the guide portion 423aK side, and the heat receiving portion 32K moves relative to the developing unit 19K. There is a possibility that the predetermined pressing force cannot be exhibited. Therefore, when the engagement hole 423K is configured as shown in FIG. 23, the mounting direction of the image forming unit 11K of the holding member 41K is such that the engagement pin 140K of the holding member 41K cannot move from the tip of the locking portion 423bK. It is necessary to provide a lock mechanism for locking the movement with respect to.
Further, as shown in FIG. 24, a groove 423cK in which the engaging pin 140K stops may be provided in the locking portion 423bK. By providing the groove 423cK in this manner, when the engaging pin 140K moves to the tip of the locking portion 423bK, the engaging pin 140K moves away from the developing unit 19K, and the pressing force of the heat receiving portion 32K against the developing unit 19K. Decrease. For this reason, when the engagement pin 140K reaches the tip of the locking portion 423bK, the user can feel a click, and when the user moves the holding member 41K and performs the contact / separation operation of the heat receiving portion 32K, the holding is performed. There is an advantage that it becomes easy to understand that the engaging pin 140K of the member 41K hits the tip of the locking portion 423bK.

Further, the image forming unit 11K is attached to the apparatus main body with some backlash due to the property of being detachable from the apparatus main body. For this reason, the image forming unit 11K may be mounted somewhat obliquely with respect to the apparatus main body. As described above, when mounted obliquely, the first engaged portion 191K is caught by the first engaging portion 161K, or the second engaged portion 192K is caught by the second engaging portion 162K during mounting. , May not be installed well. However, in the present embodiment, the support member 42K is fixed to the fixing member 50K so as to be swingable in parallel with the pressing direction of the coil spring 142K. Therefore, when the image forming unit 11K is mounted obliquely with respect to the apparatus main body and the engaged portions 191K and 192K abut against the engaging portions 161K and 162K, the support member 42K swings and the support member 42K is moved. Parallel to the image forming unit 11K. Thus, the engaged portions 191K and 192K of the developing unit 19K can be mounted without being caught by the engaging portions 161K and 162K.
In the present embodiment, the support member 42K is fixed to the fixing member 50K at two locations, but any number of fixing locations may be used. However, if the number of fixing points is increased, the restraint becomes over-constrained and the support member 42K cannot be smoothly swung. Further, a nylon washer is sandwiched between the mounting portion 421dK of the support member 42K and the stepped screw 150K, and between the support member fixing base 51K of the fixing member 50K and the mounting portion 421dK of the support member 42K. You may apply grease. As a result, when the image forming unit 11K is mounted obliquely with respect to the apparatus main body and the engaged portions 191K and 192K abut against the engaging portions 161K and 162K, the support member 42K swings smoothly, and more The image forming unit 11K can be mounted more easily.

  In the present embodiment, the holding member 41K is supported with respect to the support member 42K only by the engagement pin 140K provided at the center in the longitudinal direction of the holding member 41K. Furthermore, as shown in FIG. 21, the holding member 41K is supported by the support member 42K so that a gap is formed between the facing portion 41aK of the holding member 41K and the back surface portion 421aK of the support member 42K. Accordingly, the holding member 41K can be supported so as to be swingable about the engagement pin 140K. As a result, when the heat receiving portion 32K is pressed against the side surface of the developing unit of the image forming unit 11K mounted obliquely with respect to the apparatus main body, the holding member 41K rotates about the engagement pin 140K, and the heat receiving portion 32K is moved. It can be pressed parallel to the side surface of the developing unit 19K. Thereby, the heat receiving portion 32K can be pressed against the developing unit 19K with a uniform pressing force, and the developing unit 19K can be cooled uniformly.

Moreover, you may comprise the holding member 41K with a heat conductivity material lower than the heat receiving part 32K. By configuring the holding member 41K with a thermal conductivity material lower than that of the heat receiving portion 32K, it is possible to suppress an increase in the temperature of the holding member 41K and to reduce the amount of heat transferred from the holding member 41K to the heat receiving portion 32K. As described above, the heat receiving portion 32K is made of copper having a thermal conductivity of approximately 400 [W / mK] or aluminum having a thermal conductivity of approximately 200 [W / mK]. It is preferable to use a resin such as POM having a low thermal conductivity, for example, about 0.2 [W / mK].
Further, the entire holding member 41K may not be made of a heat conductivity material lower than that of the heat receiving portion 32K, but may be partially made of a heat conductivity material. For example, as shown in FIG. 25, a sheet 410K made of a thermal conductivity material lower than that of the heat receiving portion 32K is attached to the outer surface of the holding member 41K, or is attached to the inner surface of the holding member 41K as shown in FIG. May be. Further, a material having a lower thermal conductivity than the heat receiving portion 32K may be applied to the inner surface and the outer surface of the holding member 41K. In this way, for example, if the strength of the base material is increased, the strength of the holding member 41K can be ensured. Further, if a material having a lower thermal conductivity than that of the heat receiving portion 32K is applied, there is a merit that this can be performed as post-processing.

  Furthermore, it is preferable that the member contacting the heat receiving portion 32K, the stepped screw 141K, and the coil spring 142K be made of a material having a lower thermal conductivity than the heat receiving portion 32K. Thereby, the heat transfer by the heat conduction from the stepped screw 141K or the coil spring 142K to the heat receiving portion 32K can be reduced. Further, the screw hole 32dK of the heat receiving part 32K and the bottom part 32eK of the round groove 32cK may be made of a heat conductivity material lower than that of the heat receiving part 32K. Even if comprised in this way, the heat transfer by the heat conduction from the stepped screw 141K or the coil spring 142K to the heat receiving part 32K can be reduced.

  Further, since the support member 42K has a heat quantity from the fixing device 50K due to heat conduction from the apparatus main body, when the engagement pin 140K is made of a high thermal conductivity material, the support member 42K passes through the engagement pin 140K. Heat is conducted to the holding member 41K. Therefore, it is preferable that the engaging pin 140K of the holding member 41K is made of a heat conductivity material lower than that of the heat receiving portion 32K. In this way, by configuring the engagement pin 140K with a heat conductivity material lower than that of the heat receiving portion 32K, heat conduction from the support member 42K to the holding member 41K via the engagement pin 140K can be suppressed and retained. The temperature rise of the member 41K can be suppressed. Thereby, the amount of heat transmitted from the holding member 41K to the heat receiving part 32K can be reduced, and the cooling efficiency of the developing unit 19K by the heat receiving part 32K can be further improved.

Further, in the present embodiment, since the holding member 41K is supported by the support member 42K so as to be swingable about the engagement pin 140K, when the image forming unit 11K is extracted from the apparatus main body, the apparatus In some cases, the longitudinal end of the holding member 41K comes into contact with the support member 42K due to vibration or the like. As described above, when contact is made, the temperature of the holding member 41K rises due to heat conduction through the contact surface, which may impair the cooling efficiency of the developing unit 19K by the heat receiving portion 32K.
Therefore, as shown in FIG. 27, magnets 411K are arranged at both longitudinal ends of the support member 42K and both longitudinal ends of the holding member 41K, and the longitudinal ends of the holding member 41K are utilized by utilizing the repulsive force of the magnet 411K. Does not come into contact with the support member 42K. Further, the attractive force of the magnet 411K is used to balance the magnetic force between the support member 42K and the holding member 41K so that the longitudinal end portion of the holding member 41K does not come into contact with the support member 42K. However, when using the attractive force of magnetic force, if the balance of the magnetic force is lost, the end of the holding member 41K in the longitudinal direction comes into contact with the support member 42K, so that the repulsive force rather than using the attractive force of magnetic force. It is this way to use.
As shown in FIG. 28, spacers 214 made of a thermal conductivity material lower than that of the heat receiving portion 32K may be disposed at both ends in the longitudinal direction of the support member 42K. By doing in this way, the edge part of holding member 41K will contact spacer 214, and it can control heating of holding member 41K. In the example shown in FIG. 28, the spacers 214 are provided at both ends of the support member 42K, but the spacers 214 may be provided at both ends of the holding member 41K.

[Modification 1]
Next, Modification 1 of the present embodiment will be described.
In the first modification, the heat receiving portion is pressed against the lower surface of the developing unit. As shown in FIG. 29, when the exposure unit 9 has a space on the lower surface of the developing unit such as an image forming apparatus below the image forming unit 1, the heat receiving unit should be in pressure contact with the lower surface of the developing unit. The developing device can be efficiently cooled, which is preferable. This is because the bottom surface of the developing unit where the frictional heat due to the friction between the developer agitating / conveying member and the developer and the frictional heat due to the friction between the developers generate the highest temperature. For this reason, the developing unit can be efficiently cooled by bringing the heat receiving portion into pressure contact with the lower surface of the developing unit and actively cooling the lower surface of the developing unit.

30 is a diagram illustrating a state in which the K-color heat receiving portion 32K is pressed against the lower surface of the developing unit 19K, and FIG. 31 is a diagram illustrating a state in which the heat receiving portion 32K is separated from the lower surface of the developing unit 19K. .
As shown in FIGS. 30 and 31, the configuration of the contact / separation mechanism 40 </ b> K of the heat receiving portion 32 </ b> K is the same as that of the above embodiment. That is, the contact / separation mechanism 40K is held by the holding member 41K in a state where the heat receiving portion 32K is urged toward the developing unit by the coil spring 142K, and is engaged at the central portion in the longitudinal direction of the holding member 41K. The holding member 41K is supported by the pin 140K being engaged with the engagement hole of the support member 42K. As shown in FIG. 18, the engagement hole is composed of a guide portion and a locking portion.

  A first engaged portion 191K is provided on the left side surface in the drawing of the developing unit, and a second engaged portion 192K is provided on the right side (photoconductor side) in the drawing. Then, as shown in FIG. 30, when the heat receiving portion 32K is in pressure contact with the lower surface of the developing unit 19K, the first engaged portion 191K is provided at the left end of the support member 42K in the drawing. The second engaged portion 192K comes into contact with the second engaging portion 162K provided at the right end of the support member 42K in the drawing, hitting the joint portion 161K. Thereby, the reaction of the pressing force by which the coil spring 142K pushes the heat receiving portion 32K can be exerted on the first engaged portion 191K and the second engaged portion 192K of the developing unit 19K. Thereby, the pressing force of the heat receiving portion 32K applied to the lower surface of the developing unit 19K becomes an internal force generated inside the developing unit 19K, and the force due to the pressing force from the heat receiving portion 32K received by the positioning plate (not shown) from the developing unit 19K. And the deformation of the positioning plate can be suppressed. Therefore, fluctuations in the development gap can be suppressed.

  Further, when the holding member 41K is pulled toward the front side of the apparatus, as shown in FIG. 31, the holding member 41K moves downward, and the heat receiving portion 32K held by the holding member 41K is separated from the lower surface of the developing unit 19K. . As a result, the engagement between the engaging portions 161K and 162K and the engaged portion is released, and the engaging portions 161K and 162K and the engaged portions 191K and 192K can be moved relative to each other in the developing unit attaching / detaching direction. It becomes. Therefore, when the image forming unit 11K is pulled out from the apparatus main body, the reaction force of the pressing force from the heat receiving portion 32K and the pressing force from the engaging portions 161K and 162K is not applied to the developing unit 19K. It can be easily removed from the main body.

Further, as shown in FIG. 32, the support member 42K may be fixed to the apparatus main body via an elastic member 151K. With this configuration, the elastic member 151K is elastically deformed when the image forming unit 11K is mounted obliquely with respect to the apparatus main body and the engaged portions 191K and 192K abut against the engaging portions 161K and 162K. Thus, the support member 42K can take a posture parallel to the image forming unit 11K. Thus, the engaged portions 191K and 192K of the developing unit 19K can be mounted without being caught by the engaging portions 161K and 162K. Further, as shown in FIG. 33, when the image forming unit 11K is taken out from the apparatus main body, even if the support member 42K is lowered by its own weight, the engaging portions 161K and 162K are engaged portions indicated by dotted lines in the drawing. An elastic member 151K having an urging force that comes above 191K and 192K is used.
The urging force of the elastic member 151K is weaker than the urging force (pressing force) of the coil spring 142K. As a result, when the holding member 41K is moved to the rear side of the apparatus and the heat receiving portion 32K comes into contact with the developing unit 19K, the support member 42K is moved downward by the reaction force from the developing unit 19K, and each engagement is performed. The portions 161K and 162K can be brought into contact with the engaged portions 191K and 192K. Thereby, the engaged parts 161K and 162K can surely receive the reaction of the pressing force from the heat receiving part. In addition, since the heat receiving portion 32K can be reliably pressed with a predetermined pressing force, the heat receiving portion 32K can be brought into close contact with the lower surface of the developing unit 19K.

  In the case of an image forming apparatus in which the exposure unit 9 is located below the image forming unit 1 as shown in FIG. 29, the developing units 19Y, M, C, and K are connected by one heat receiving unit 32 as shown in FIG. It may be cooled. The heat receiving portion 32 has a through-hole for passing a laser beam irradiated to the Y-color photoconductor, a through-hole for passing a laser beam irradiated to the M-color photoconductor, and a laser beam irradiated to the C-color photoconductor. A through-hole is provided for passing through. The contact / separation mechanism includes a holding member 41 that holds the heat receiving portion 32 and four engaging members 342Y, M, C, and K corresponding to the developing units 19Y, 19M, 19C, and 19K. The second engagement portion 342bK of the K-color engagement member 342K and the first engagement portion 342aY of the Y-color engagement member 342Y are provided with engagement holes as shown in FIG. Engagement pins 140K provided on the holding member 41 are engaged with each other. Similar to the heat receiving portion 32, the holding member 41 is a through-hole for passing a laser beam irradiated to the Y-color photoconductor, a through-hole for passing a laser beam irradiated to the M-color photoconductor, and a C-color photoconductor. A through hole is provided for passing the laser beam to be irradiated. The holding member 41 elastically holds the heat receiving portion 32 via coil springs 142Y, 142M, 142C, 142K provided at locations facing the lower surface of each developing unit. The first engagement portion 342aK of the K-color engagement member 342K, the first and second engagement portions 342aC and 342bC of the C-color engagement member 342C, and the first and second engagements of the M-color engagement member 342M The through holes through which the holding member 41 and the heat receiving portion 32 pass are provided in the portions 342aM, 342bM and the second engaging portion 342bY of the Y-color engaging member 342Y.

  Here, when replacing the K-color image forming unit 11K, the holding member 41 is moved to the front side of the apparatus to separate the heat receiving portion 32 from the developing units 19Y, 19M, 19C, and 19K, and then the image forming unit. Remove 11K from the main body. When the new K-color image forming unit 11K is replaced, the holding member 41 is moved to the rear side of the apparatus, and the heat receiving portion 32 is pressed against each developing unit 19Y, M, C, K. Then, the engaging members 342Y, M, C, and K of the respective colors engage with the developing units 19Y, M, C, and K, and the developing units 19Y, 19M, C, and K of the respective colors react with the reaction force from the heat receiving unit 32. Can receive. Thereby, the force resulting from the pressing force from the heat receiving part 32 received from the developing units 19Y, 19M, 19C, and 19K on the positioning plates for each color can be reduced. Thereby, a deformation | transformation of the positioning plate of each color can be suppressed.

[Modification 2]
Next, a second modification of the present embodiment will be described.
In the second modification, the heat receiving portion is pressed against the lower surface and the side surface of the developing unit. As described above, since the developing unit is cooled on two sides, the developing unit can be cooled more efficiently.

FIG. 37 is a cross-sectional view of the periphery of the K-color image forming unit in the image forming apparatus according to the second modification.
As shown in the drawing, in the second modification, the heat receiving portion 32K is formed in an L-shaped cross section. As shown in FIG. 38, in the second modification, the lower surface and the side surface of the heat receiving portion 32K are held by the holding member 41K while being biased toward the developing unit by the coil spring 142K. Further, as shown in FIG. 37, the heads of the stepped screws 141K fixed to the lower surface of the heat receiving part 32K are in contact with the holding members, respectively.

  As shown in FIG. 38, an engagement pin 143K is provided on the head of the stepped screw 141 that is fixed to the longitudinal center of the lower surface of the heat receiving portion 32K. An engaging pin 140K is caulked and fixed at the center in the longitudinal direction of the first bent portion 41cK of the holding member 41K, as in the embodiment. The holding member 41K is supported by the engagement pins 140K and 143K being engaged with the engagement holes of the support member 42K. As shown in FIG. 18, the engagement hole is composed of a guide portion and a locking portion.

  The support member 42K is fixed to the support member fixing base 51K of the fixing member 50K by a step screw 150K so as to be movable in the vertical and horizontal directions in the figure relative to the fixing member 50K.

FIG. 39 is a schematic perspective view showing the vicinity of the first engagement portion of the second modification.
In the second modification, the first engagement portion 161K includes a protruding portion 161aK that protrudes from the rear end of the apparatus at the tip of the support portion 421bK of the first member 421K toward the developing unit, and a hook-shaped portion 161bK. ing.

  The first engaged portion 191K for engaging with the first engaging portion 161K is provided at the end on the back side of the side surface of the developing unit. As in the embodiment, the first engaged portion 191K includes a portion protruding from the side surface and a portion extending downward from the tip of the protruding portion. Further, the developing unit 19K has a first pedestal surface 193K so as to face a portion protruding from the side surface of the first engaged portion 191K. A first guide surface 195K that is inclined downward from the first pedestal surface 193K is provided behind the first pedestal surface 193K.

FIG. 40 is a schematic configuration diagram illustrating the periphery of the second engagement portion of the second modification. In FIG. 40, the developing unit 19K is partially omitted for easy understanding of the configuration of the second engaging portion and the second engaged portion.
As shown in FIG. 40, in the second modified example, the second engagement portions 162aK and 162bK are provided at two locations on the device rear side end portion and the front side end portion of the second member 422K. Protruding to The tip portions of the second engaging portions 162aK and 162bK are bent inward. In addition, on the back side and the near side of the second engaged portion 192K provided in the developing unit 19K, second pedestal surfaces 194aK and 194bK that protrude from the second engaged portion 192K to the photosensitive member side are provided, respectively. Yes. On the back side of the second pedestal surfaces 194aK and 194bK, second guide surfaces 196aK and 196bK that are inclined downward are provided.

  Further, the protruding amount of the second engaging portion 162bK on the near side is smaller than the protruding amount of the second engaging portion 162aK on the far side, and the position where the second pedestal surface 194bK on the near side is provided. Is provided at a position lower than the second pedestal surface 194aK on the back side, and when the image forming unit is mounted, the second engaging portion 162bK on the front side is connected to the second pedestal portion 196aK on the back side, the second guide surface 196196aK, etc. It does not come into contact. Not limited to this, the amount of protrusion upward of the second engagement portion 162aK on the back side is made smaller than the amount of protrusion of the second engagement portion 162bK on the near side, and the second pedestal surface 194aK on the back side is The position to be provided may be provided at a position lower than the second pedestal surface 194bK on the near side, and the height relationship between the near side and the far side may be reversed. When the developing unit 19K can be inserted into the image forming apparatus while being inclined in the vertical direction, the heights of the second pedestal portion and the second engaging portion on the front side and the back side may be the same.

Next, the contact / separation of the heat receiving portion 32K with respect to the developing unit 19K in Modification 2 will be described.
When the image forming unit 11K is taken out from the apparatus main body, as shown in FIG. 41, the attachment portion 421dK of the support member 42K is placed on the support member fixing base 51K of the fixing member 50K. As the image forming unit 11K is inserted, the protruding portion 161aK of the first engaged portion 161K abuts on the first guide surface 195K. Further, the second engagement portions 162aK and 162bK on the back side and the near side abut on the second guide surfaces 196aK and 196bK, respectively. When the developing unit 19K is further mounted from this state, the support member 42K is guided by the second guide surfaces 196aK and 196bK and the first guide surface 195K and moves upward. In addition, the holding member 41K and the heat receiving portion 32K move upward together with the support member 42K, and the heat receiving portion 32K comes into contact with the lower surface of the developing unit 19K. Further, when the developing unit 19K is attached to the apparatus main body, as shown in FIG. 42, the rear side and front side second engaging portions 162aK and 162bK are placed on the second pedestal surfaces 196aK and 196bK, respectively. The protruding portion 161aK of the portion 161K rests on the first pedestal surface 193K. At this time, the coil spring 142K that presses the lower surface of the heat receiving part 32K compresses and presses the heat receiving part 32K upward. Thereby, the heat receiving part 32K can be press-contacted to the lower surface of the developing unit 19K. Further, the reaction of the pressing force of the coil spring 142K that presses the lower surface of the heat receiving portion 32K presses the heat receiving portion 32K acts on the head of the step screw 144K fixed to the lower surface of the heat receiving portion 32K, and the step screw 144K The support member 42K is pressed downward. As a result, the reaction of the pressing force acts on the first pedestal surface 193K of the developing unit 19K from the protruding portion 161aK of the first engaging portion 161K of the support member 42K, and the second engaging portions 162aK and 162bK of the support member 42K. Acts on the second pedestal surfaces 196aK and 196bK of the developing unit 19K. As a result, the developing unit 19K can receive a reaction of a pressing force that pushes the developing unit 19K upward from the heat receiving portion 32K. Therefore, the pressing force that pushes the developing unit upward by the heat receiving portion 32K can be used as the internal force of the developing unit 19K.

  As shown in FIG. 42, when the developing unit 19K is mounted on the apparatus main body, the lever (not shown) is operated to move the holding member 41K to the back side of the apparatus in the same manner as in the embodiment. Similarly to the embodiment, the reaction force from the side surface of the developing unit 19K is transmitted from the heat receiving portion 32K to the supporting member 42K via the engaging pin 140K of the holding member 41K, and the supporting member 42K is separated from the developing unit 19K. Move to the left in the figure. As a result, as shown in FIG. 37, the engaged portions 191K and 192K of the developing unit 19K and the engaging portions 161K, 162aK, and 162bK of the contact / separation mechanism come into contact with each other, and the reaction received by the support member 42K is developed. It extends to the engaged portions 191K and 192K of the unit 19K.

  Thus, also in the second modification, the pressing force received from the heat receiving portion can be made the internal force of the developing unit, and the positioning plates 111K, 112K and the like are received from the developing unit 19K (due to the pressing force from the heat receiving portion 32K). Force) can be reduced. Therefore, it is possible to suppress the deformation of the positioning plates 111K, 112K and the like, it is possible to suppress the change in the development gap, and it is possible to maintain a high-quality image over time.

[Modification 3]
Next, Modification 3 of the present embodiment will be described.
In Modification 3, as shown in FIG. 43, the engagement pin 140K is caulked and fixed to the back end of the holding member 41K, and the engagement hole 423 is formed in the back end of the support member 42K as shown in FIG. The engagement pin 140K provided at the back end of the holding member 41K is engaged with the engagement hole 423 provided at the back end of the support member 42K. As a result, the holding member 41K is supported by the support member 42K so as to be able to swing around the back end.

  By having the configuration as in Modification 3, if the heat receiving portion 32K is pressed against the developing unit 19K as described below, the friction between the pressure contacting surface of the heat receiving portion 32K and the side surface of the developing unit 19K is reduced to the back side. It can only be near the edge. That is, the front end of the holding member 41K is moved toward the support member 42K, the front side of the heat receiving portion 32K is sufficiently separated from the side surface of the developing unit 19K, and the holding member 41K is moved to the back side of the apparatus. In this way, by moving the holding member 41K to the back side of the apparatus, only the vicinity of the back end portion of the heat receiving portion 32K can be slid against the side surface of the developing unit 19K. As a result, the sliding surface between the developing unit 19K and the heat receiving portion 32K can be reduced, and the durability can be improved. In particular, when the heat conductive sheet 130K is provided between the heat receiving unit 32K and the developing unit 11K, deterioration of the heat conductive sheet 130K can be reduced. This is because the heat conductive sheet 130K is softer than metal, and therefore, when the heat conductive sheet 130K slides with the developing unit 19K (or the heat receiving portion 32K), the heat conductive sheet 130K is easily damaged.

  When the holding member 41K is moved to the back side of the apparatus, the holding member 41K is fixed to the developing unit 19K using a lock mechanism (not shown) provided on the front side of the holding member 41K. By fixing the holding member 41K to the developing unit 19K by the locking mechanism (not shown), the reaction of the pressing force of the coil spring 142K is applied to the developing unit 19K via the locking mechanism (not shown) at the front end of the apparatus. It extends. On the other hand, on the rear side of the holding member 41K, when the front end of the holding member 41K is fixed to the developing unit 19K by the lock mechanism, the reaction force from the developing unit 19K is applied via the engaging pin 140K. The support member 42K receives. Then, the support member 42K moves away from the developing unit 19K, and the engaging portions 161K and 162K of the supporting member 42K engage with the developing unit 19K. Accordingly, on the back side of the apparatus, the reaction of the pressing force of the coil spring 142K reaches the developing unit 19K via the engaging portions 161K and 162K of the support member 42K. As a result, the contacting / separating mechanism 40K is fixed to the developing unit 19K, the developing unit 19K and the contacting / separating mechanism 40K are integrated in the apparatus, and the heat receiving portion 32K pushes the wall surface of the developing unit 19K. The pressure can be applied as an internal force in the developing unit 19K. As a result, the force that the positioning plates 111K, 112K, etc. receive from the developing unit 19K (due to the pressing force from the heat receiving portion 32K) can be reduced, and the deformation of the positioning plates 111K, 112K, etc. can be suppressed. Can do.

  Also in the third modification, the holding member 41K is supported so as to be swingable about the engagement pin 140K. Therefore, when the heat receiving portion 32K is pressed against the side surface of the developing unit of the image forming unit 11K mounted obliquely with respect to the apparatus main body, the holding member 41K rotates about the engaging pin 140K, and the heat receiving portion 32K is developed. It can be pressed parallel to the side surface of the unit 19K. Thereby, the heat receiving portion 32K can be pressed against the developing unit 19K with a uniform pressing force, and the developing unit 19K can be cooled uniformly.

  In Modification 3, as shown in FIG. 45, the developing unit 19K is provided with a protruding portion 73 that is provided on the back side of the developer accommodating portion 80 and protrudes from the back side surface of the developing unit 19K. When 19K is attached to the apparatus main body, the rear side end of the heat receiving part 32K may be on the back side of the apparatus with respect to the agent container 80 of the developing unit 19K. By configuring in this way, as described above, when the front side of the holding member 41K is moved toward the support member 42K and the holding member is moved to the back side of the apparatus, the vicinity of the back end of the heat receiving portion 32K is Rub with the protrusion 73. Since the protrusion 73 does not need to be cooled, there is no problem even if the vicinity of the rear end of the heat receiving part 32K is damaged by the rubbing with the protrusion 73. Thereby, it is possible to suppress damage due to friction between the pressure contact surface of the heat receiving portion 32K facing the agent accommodating portion 80 of the developing unit 19K and the side surface of the developing unit, which are highly required to be cooled. As a result, the adhesiveness between the pressure contact surface of the heat receiving portion 32K facing the agent accommodating portion 80 of the developing unit 19K and the side surface of the developing unit can be secured over time, and good cooling performance can be maintained over time. Note that the protrusion 73 is not necessarily provided.

Moreover, in this modification 3, as shown in FIG. 46, you may provide the protective layer 71 in the back end part of the heat receiving part 32K. 46A shows an example in which the heat conductive sheet 130K is not provided on the pressure contact surface of the heat receiving part 32K, and FIG. 46B shows the heat conductive sheet 130K on the pressure contact surface of the heat receiving part 32K. It is a figure which shows the example provided. By providing the protective layer 71 as described above, when the front side of the holding member 41K is moved toward the support member 42K and the holding member 41K is moved to the back side of the apparatus as described above, the protective layer 71 is not attached to the developing unit 19. By rubbing against the side surface, the heat receiving portion 32K (or the heat conductive sheet 130K) can be prevented from being damaged. Further, by making the protective layer 71 a low friction member, the sliding property with the developing unit 19K can be improved, and the durability between the protective layer 71 and the developing unit 19K can be improved. Further, the protective layer 71 may be provided at the rear end of the developing unit 19K, or may be provided at both the developing unit 19K and the heat receiving part 32K.
45 and 46, the thickness of the protective layer 71 is shown as being thicker for the sake of clarity. However, the protective layer 71 is actually a thin film, and the development unit 19K of the heat receiving portion 32K is provided by providing the protective layer 71. There is almost no influence of the pressure contact force.

  In the above description, the developing unit and the photosensitive member are positioned by the positioning plate, and the developing unit is integrated with the photosensitive member as an image forming unit and is attached to and detached from the apparatus main body. The structure which can be attached or detached from the forming apparatus main body may be sufficient. In this case, when the developing unit is mounted on the apparatus main body, the developing unit is positioned on the positioning member in the apparatus main body, and the gap between the photosensitive member and the developing roller is maintained at a predetermined value. As described above, even when the developing unit is detachably attached to the apparatus main body, by applying the present invention, the force caused by the pressing force of the heat receiving portion received by the positioning member in the apparatus main body from the developing unit can be obtained. Can be reduced. Thereby, a deformation | transformation of a positioning member is suppressed and a highly accurate image development gap can be maintained.

  The present invention is not limited to an intermediate transfer tandem color image forming apparatus. For example, as shown in FIG. 35, the present invention can also be applied to a direct transfer tandem type color image forming apparatus. The present invention has been described with respect to an image forming apparatus employing a two-component development system in which a development gap is formed between a photosensitive member and a developing roller to perform development. However, development is performed by bringing the developing roller into contact with the photosensitive member. The present invention can also be applied to an image forming apparatus that employs a one-component developing system. Even in an image forming apparatus that employs this one-component development method, there is a problem that the contact pressure between the developing roller and the photosensitive member is increased by bringing the heat receiving portion into pressure contact with the developing unit. The pressing force of the heat receiving portion becomes an internal force, and an increase in the contact pressure between the developing roller and the photosensitive member due to the pressing force of the heat receiving portion can be suppressed.

[Modification 4]
FIG. 47 is a diagram when the liquid cooling device 30 is attached to the waste toner collecting unit 97 of the intermediate transfer belt cleaning unit 90 as the cooled portion.

  The intermediate transfer belt cleaning unit 90 includes a cleaning brush roller 91 that removes paper dust and toner adhering to the surface of the intermediate transfer belt 15 by rubbing against the surface of the intermediate transfer belt 15, and paper dust adhering to the cleaning brush roller 91. Flicker 96 that scrapes toner from the cleaning brush roller 91, cleaning blade 92 that is provided in contact with the surface of the intermediate transfer belt 15 and removes toner etc. from the surface of the intermediate transfer belt 15, intermediate transfer by the cleaning brush roller 91 and the cleaning blade 92 A waste toner collecting unit 97 that collects toner and the like removed from the surface of the belt 15, and the toner collected by the waste toner collecting unit 97 is merged with waste toner collected at other portions of the image forming apparatus and accumulated. Waste toner accumulator (not shown) On the surface of the intermediate transfer belt applied by the lubricant application brush roller 94, the lubricant application brush roller 94 for applying the lubricant 93 to the surface of the intermediate transfer belt 15, and the intermediate transfer belt 15. It is composed of a lubricant leveling blade 95 that stretches and leveles the lubricant. Further, the cleaning brush roller 91, the flicker 96, the cleaning blade 92, the waste toner collecting unit 97, the lubricant application brush roller 94, the lubricant leveling blade 95, and the like are integrated with the support plate 99 of the intermediate transfer belt cleaning unit 90. It is provided in and is unitized.

  The toner removed by the cleaning brush roller 91 and the cleaning blade 92 that removes the toner and the like is collected by the waste toner collecting unit 97 and then collected by the conveying screw 98 at other locations in the image forming apparatus. And merged and accumulated in the waste toner accumulation unit.

  Here, as can be seen from FIG. 1, the intermediate transfer belt cleaning unit 90 is located near the fixing device 7. Therefore, the toner in the waste toner collecting unit is melted by heat generated from the fixing device 7 during the image forming operation, and the melted toner is not affected by the heat from the fixing device 7 after the image forming operation is finished. The toner may be fixed to the inner side surface of the toner recovery unit 97, the conveying screw 98, or the like. Further, the toner in the waste toner collecting unit is melted by heat generated by the rotation of the conveying screw 98, and the melted toner may be fixed to the inner side surface of the waste toner collecting unit 97, the conveying screw 98, or the like. Therefore, in order to prevent the toner from sticking, in this embodiment, the heat receiving portion 32 of the liquid cooling device 30 is pressed against the wall surface of the waste toner collecting portion 97 in the intermediate transfer belt cleaning unit 90 via the heat conductive sheet 130. As described above, the liquid cooling device 30 was attached to the waste toner collecting unit 97.

  The waste toner collecting portion 97 is provided with a first engaged portion 191 and a second engaged portion 192, and the first engaging portion provided in the contact / separation mechanism of the liquid cooling device 30 as described above. 161 and the second engaging portion 162 are respectively engaged. With this configuration, the reaction of the pressing force by the coil spring 142 which is the pressing means provided in the contact / separation mechanism 40 can be applied to the first engaged portion 191 and the second engaged portion 192 of the waste toner collecting portion 97. be able to.

  As described above, in the present modification, when the heat receiving unit 32 is brought into pressure contact with the wall surface of the waste toner collecting unit 97, the reaction of the pressing force applied to the coil spring 142 from the heat receiving unit 32 is affected by the first engagement of the waste toner collecting unit 97. By being able to reach the joint portion 101 and the second engaged portion 192, the pressing force applied to the wall surface of the waste toner collecting portion 97 from the heat receiving portion 32 becomes an internal force.

  Therefore, in this modified example, it is possible to cool the waste toner in the waste toner collecting unit while suppressing the fluctuation in the distance between the cleaning blade 92 that cleans the surface of the intermediate transfer belt and the intermediate transfer belt 15. Further, the conveyance screw 98 is not stopped or the machine is not stopped due to toner adhesion.

  Accordingly, when the distance between the intermediate transfer belt 15 and the cleaning blade 92 or the like is more than a predetermined value set in advance so that the surface of the intermediate transfer belt 15 can be satisfactorily cleaned by the cleaning blade 92 or the like, the intermediate transfer belt The toner adhering to the toner 15 cannot be scraped off by the cleaning blade 92 or the like, and the next transfer is performed while the surface of the intermediate transfer belt 15 is dirty, causing problems such as the image becoming dirty. Can be suppressed.

  On the contrary, when the distance between the intermediate transfer belt 15 and the cleaning blade 92 becomes closer than the specified value, the cleaning blade 92 is bent and the cleaning blade 92 is damaged or the intermediate transfer belt 15 is damaged. It can suppress that it causes.

  As described above, according to the image forming apparatus of the present embodiment, when the heat receiving portion is brought into pressure contact with the wall surface of the developing unit, the reaction of the pressing force from the heat receiving portion applied to the coil spring serving as the pressing means is applied to a predetermined portion of the developing unit. By doing so, the pressing force applied from the heat receiving portion to the wall surface of the developing unit becomes an internal force, and the force due to the pressing force from the heat receiving portion received by the positioning plate as the positioning means from the developing unit can be reduced. As a result, fluctuations in the gap between the photosensitive member as the latent image carrier and the developing device as the developer carrier can be suppressed.

  The contact / separation mechanism includes a receiving unit including a support member and a holding member that are subjected to the reaction of the pressing force, and the receiving unit includes an engaging portion that engages with an engaged portion of the developing unit. When the receiving means receives a reaction of the pressing force, the engaging portion engages with the engaged portion, and the contact / separation mechanism is fixed to the developing unit, so that the pressing force from the heat receiving portion on the coil spring is applied. This reaction can be applied to the engaged portion of the developing unit.

  Further, when the heat receiving portion is separated from the developing unit, the engaging portion and the engaged portion can be moved relative to each other in the developing unit attaching / detaching direction, so that the developing unit can be easily removed from the apparatus main body. Can do.

  Further, the contact / separation mechanism includes a support member that is a support unit that supports the holding member so as to be able to contact and separate from the developing unit, and by operating the holding member, the heat receiving portion is brought into contact with and separated from the developing unit. be able to.

  In addition, the holding member has an engagement pin, and the support member has an engagement hole that engages with the engagement pin and guides the engagement pin in the direction of moving toward and away from the developing unit. By operating, the heat receiving part can be brought into and out of contact with the developing unit. Moreover, it can prevent that a holding member remove | deviates from a supporting member.

  Moreover, it can suppress that the calorie | heat amount of a support member is conducted from an engagement pin to a holding member by comprising an engagement pin with a heat conductivity material lower than a heat receiving part. Thereby, the temperature rise of a holding member can be suppressed and the temperature rise of the heat receiving part by the heat | fever of a holding member can be suppressed. As a result, it is possible to suppress a decrease in the cooling efficiency of the developing unit.

  Further, by providing the engaging pin at the center of the holding member in the direction of attaching / detaching the developing unit, the holding member is supported so as to be swingable about the engaging pin. Thereby, even if the developing unit is mounted to be inclined with respect to the apparatus main body, the holding member swings around the engaging pin, so that the holding member is parallel to the side surface of the developing unit. it can. Thereby, even if the developing unit is mounted to be inclined with respect to the apparatus main body, the heat receiving portion can be uniformly pressed in the longitudinal direction of the developing unit, and the developing unit can be cooled uniformly in the longitudinal direction.

  Further, the holding member is configured such that both ends of the developing unit in the attaching / detaching direction of the back surface of the supporting member and both ends of the developing unit in the attaching / detaching direction of the surface facing the back surface of the supporting member of the holding member are magnetically repelled or attracted. It can suppress that the longitudinal direction edge part contacts a support member. Thereby, it can suppress that a heat | fever conducts from a support member to a holding member, and can suppress the temperature rise of a holding member. Therefore, the temperature rise of the heat receiving portion due to the heat of the holding member can be suppressed, and the decrease in the cooling efficiency of the developing unit can be suppressed.

  Further, spacers made of a thermal conductivity material lower than that of the heat receiving part at both ends of the developing unit attaching / detaching direction on the back surface of the supporting member or at both ends of the developing unit attaching / detaching direction on the surface facing the back surface of the supporting member of the holding member. By providing this, the longitudinal end of the holding member comes into contact with the spacer and does not come into contact with the support member. Since the spacer is made of a thermal conductivity material lower than that of the heat receiving portion, heat conduction from the spacer to the holding member can be suppressed even if the holding member comes into contact with the spacer. Thereby, the temperature rise of a holding member can be suppressed and the temperature rise of the heat receiving part by the heat | fever of a holding member can be suppressed. As a result, it is possible to suppress a decrease in the cooling efficiency of the developing unit.

  Further, the engaging pin may be provided at the end on the back side of the apparatus opposite to the opening side for attaching / detaching the developing unit of the holding member. As a result, the front side of the holding member is brought close to the support member, and the holding member is moved to the back side of the apparatus, so that only the vicinity of the back end of the pressure contact surface of the heat receiving portion can be slid with the side surface of the developing unit. it can. As a result, the sliding surfaces of the developing unit 19K and the heat receiving part 32K can be reduced, and the durability of the heat receiving part 32K can be improved.

  Further, the rear end portion of the holding member is set to the back side with respect to the agent storage portion in which the developer of the developing unit is stored. As a result, the vicinity of the rear end portion of the heat receiving portion does not face the agent accommodating portion, and the portion of the heat receiving portion facing the agent accommodating portion can be prevented from being damaged by sliding with the developing unit. As a result, it is possible to ensure adhesion between the heat receiving portion facing the agent container of the developing unit and the side surface of the developing unit over time, and to maintain good cooling performance over time.

  In addition, a protective layer that protects the pressure contact surface is provided on at least one of the back end portion of the pressure contact surface that is in pressure contact with the developing unit of the heat receiving portion and the back end portion of the side surface that is the facing surface facing the heat receiving portion of the development unit. It was. Thereby, a protective layer will rub and it can prevent the damage | wound of the surface which provided the protective layer.

  Further, by using a low friction member as the protective layer, the slidability of the protective layer is improved, and damage to the protective layer and the surface that rubs against the protective layer can be suppressed.

  In addition, the engagement hole locks the engagement pin at the close position when the guide portion that guides the engagement pin in the direction of moving away from the development unit and the heat receiving portion are pressed against the wall surface of the development unit. And a locking portion. Accordingly, when the heat receiving portion is brought into contact with the developing unit and the developing unit is pressed, the engagement pin can be prevented from moving in a direction away from the developing unit due to a reaction from the developing unit. Thereby, the heat receiving portion can be pressed against the developing unit with a predetermined pressing force, and the heat receiving portion can be satisfactorily adhered to the developing unit.

  In addition, since the guide portion of the engagement hole is formed to be inclined and extended with respect to the developing unit attaching / detaching direction, the heat receiving portion is brought into contact with and separated from the developing unit simply by moving the holding member in the developing unit attaching / detaching direction. be able to. Further, by making the engaging portion of the engaging hole a portion extending in parallel with the developing unit attaching / detaching direction, the holding member can be reliably engaged at a predetermined position. Thereby, the heat receiving portion can be pressed against the developing unit with a predetermined pressing force, and the heat receiving portion can be satisfactorily adhered to the developing unit.

  Further, by using an elastic member as the pressing means, it is possible to easily change the pressing force only by changing the type of the elastic member.

  Further, by providing a plurality of elastic members in the longitudinal direction of the heat receiving portion, the heat receiving portion can be uniformly pressed in the longitudinal direction of the developing unit. Thereby, the developing unit can be cooled uniformly in the longitudinal direction.

  The elastic member is configured to be compressed and sandwiched between an elastic member abutting portion provided on a surface opposite to the pressure contact surface of the heat receiving portion and an opposing portion of the holding member. The member abutting portion is recessed toward the developing unit from the surface opposite to the pressure contact surface. Thereby, the distance of the opposing part of a holding member and an elastic member contact part can be extended rather than the distance of the opposing surface and the surface on the opposite side of a heat receiving part. Therefore, fluctuations in the pressing force of the elastic member due to fluctuations in the length of the elastic member can be reduced. In addition, since the distance between the facing portion and the surface opposite to the pressure contact surface of the heat receiving portion can be reduced, the device can be made compact.

  In addition, by supporting the contact / separation mechanism on the apparatus main body so as to be movable in a direction perpendicular to the attaching / detaching direction of the developing unit, the contact / separation mechanism moves when the developing unit is mounted obliquely to the apparatus main body. Thus, the engaging portion can be prevented from being caught by the developing unit. Thereby, even if the developing unit is mounted obliquely, the developing unit can be mounted smoothly.

  In addition, by providing a shielding unit that shields infrared light incident on the heat receiving unit from other than the wall surface of the developing unit, it is possible to suppress the heat receiving unit from being affected by heat from other than the developing unit. Thereby, the temperature rise of a heat receiving part can be suppressed and a developing unit can be cooled efficiently.

  Moreover, the infrared light which injects into a heat receiving part can be favorably shielded by using the holding member holding a heat receiving part as a shielding means.

  In addition, the member (coil spring, stepped screw) that contacts the heat receiving part of the contact / separation mechanism is made of a material having a lower thermal conductivity than the heat receiving part, so that heat from the member that contacts the heat receiving part to the heat receiving part is conducted. Can be suppressed, and the temperature rise of the heat receiving portion can be suppressed.

  Further, by bringing the heat receiving portion into pressure contact with the lower surface of the developing unit, the portion of the developing unit where the temperature rises most can be cooled by the heat receiving portion, and the developing unit can be efficiently cooled.

  In addition, by providing an elastic member as an urging means for urging the contact / separation mechanism vertically upward, the elastic member is elastically deformed when it abuts against the engagement portion of the contact / separation mechanism when the developing unit is mounted. The joint can be escaped. Accordingly, the engaging portion can be prevented from being caught by the developing unit, and the developing unit can be smoothly mounted even when the developing unit is mounted obliquely.

  Also, since the biasing force of the elastic member that biases the contact / separation mechanism vertically upward is weaker than the pressing force of the coil spring, when the heat receiving part presses the development unit, the reaction from the development unit causes the contact / separation mechanism The engaging portion can be brought into contact with the developing unit with certainty. Thereby, it is possible to reliably receive the pressing force from the heat receiving portion applied to the developing unit at the engaging portion.

  In addition, by using an elastic member as an urging means for urging the contact / separation mechanism vertically upward, the urging force can be easily changed simply by changing the type of the elastic member.

  In addition, since a plurality of image forming units having a photosensitive member as a latent image carrier and a developing unit are horizontally arranged, and the heat receiving portion is configured to be in pressure contact with the wall surfaces of the plurality of developing units, The number of heat receiving portions can be reduced as compared with the unit cooled by one heat receiving portion. Thereby, the structure of a cooling device can be simplified. In addition, when replacing a plurality of developing units, the heat receiving portion can be separated from the plurality of developing units by a single operation, so that the work for replacing the plurality of developing units can be easily performed.

  Further, the heat receiving portion may be pressed against the lower surface and the side surface of the developing unit. Thereby, the developing unit can be cooled more efficiently.

  In addition, the development unit is configured to be detachable from the apparatus main body integrally with the photoconductor while being positioned with respect to the photoconductor, so that the development unit alone can be attached to and detached from the apparatus main body. Thus, fluctuations in the development gap can be suppressed.

  In addition, by providing an adhesive sheet made of a high-efficiency heat conductive member having a lower hardness than the heat receiving part on the pressure contact surface that is in pressure contact with the developing unit of the heat receiving part, the heat conductive sheet is deformed when the heat receiving part is pressed against the developing unit. As a result, the surface accuracy between the developing unit and the heat receiving portion is reduced. Thereby, an air layer is not formed between the developing unit and the heat receiving part, and the heat of the developing unit can be conducted well to the heat receiving part.

  In the present embodiment, the liquid cooling device 30 that is a cooling device that uses a cooling liquid as a cooling medium has been described. However, the cooling medium is not limited to the cooling liquid, and other cooling medium such as a gas is used. A cooling device may be used.

1: Image forming unit 7: Fixing unit 9: Exposure unit 11Y, M, C, K: Image forming unit 15: Intermediate transfer belt 18dK: Drum shaft 18Y, M, C, K: Respective photoreceptors 19Y, M, C, K: developing unit 19aK: developing roller 19bK: secondary reference pin 30: liquid cooling device 31: cooling pump 32Y, M, C, K: heat receiving portion 32aK: case 32bK: flow path 32cK: round groove 32dK: screw hole 32eK: round The bottom of the groove (elastic member contact part)
33: Reserve tank 34: Circulation pipe 35: Cooling part 40K: Contact / separation mechanism 41K: Holding member 41aK: Opposing part 41bK: Hole 41cK: First bent part 41dK: Second bent part 42K: Support member 50K: Fixing member 51K: Support member fixing base 61: Partition plate 90: Intermediate transfer belt cleaning unit 91: Cleaning brush roller 92: Cleaning blade 93: Lubricant 94: Lubricant application brush roller 95: Lubricant leveling blade 96: Flicker 97: Waste toner collection Portion 98: Conveying screw 99: Support plate 110K: Frame 111K: Front positioning plate 112K: Back positioning plate 130K: Thermal conduction sheet 140K: Engagement pins 141K, 150K: Step screw 142K: Coil spring 151K: Elastic member 161K: No. 1 engaging portion 162K: second engaging portion 191 : First engaged portion 192K: second engaged portion 214: spacer 342Y, M, C, K: engaging member 410K: sheet 411K: magnet 421: first member 421aK: back surface portion 421bK: support portion 421cK: Fixing portion 421dK: mounting portion 421eK: elongated hole 422K: second member 423K: engagement hole 423aK: guide portion 423bK: locking portion 423cK: groove

JP 2005-164927 A

Claims (5)

A portion to be cooled which is detachably attached to the image forming apparatus main body;
A cooling device that is installed in contact with the cooled part and has a heat receiving part that receives a heat of the cooled part by flowing a cooling medium therein;
In an image forming apparatus provided with a contact / separation mechanism for contacting and separating the heat receiving unit with respect to the cooled part,
The moving mechanism includes a holding member for holding the heat receiving portion, and, said retaining member said in the direction in which the holding member from the object to be cooled the takeout direction of the object to be cooled is separated with respect to the image forming apparatus main body An image forming apparatus having a guide portion for guiding. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the guide portion is formed so that the heat receiving portion contacts the cooled portion while sliding with the cooled portion. The image forming apparatus according to claim 1 or 2,
The image forming apparatus according to claim 1, wherein the guide portion is formed on a support member that supports the holding member so that the holding member can be moved toward and away from the cooled portion. The image forming apparatus according to claim 3.
The holding member has an engagement pin,
The image forming apparatus according to claim 1, wherein the support member includes an engagement hole that engages with the engagement pin and guides the engagement pin in a direction in which the engagement pin is in contact with or separated from the cooled portion. The image forming apparatus according to claim 1, 2, 3, or 4.
The image forming apparatus is characterized in that the cooled portion is a developing unit that includes a developer carrying member that conveys the developer to a portion facing the latent image carrying member and is detachably attached to the image forming apparatus main body. Forming equipment.

Images