JP5757408B2 - 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 be melted by the temperature rise and fixed to the developer regulating member, the developer carrying member, the image carrying member, etc., and a streaky abnormal image may be generated on 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.

  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.

  In the image forming apparatus described in Patent Document 1, when attaching or detaching the developing unit, 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 to the developing unit side. The heat receiving portion is pressed to the developing unit side by the pressing means, and the contact / separation mechanism is provided in which the heat receiving portion is in close contact with the developing unit. 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.

  The contact / separation mechanism described in Patent Document 1 holds the heat receiving portion on the holding member in a state where the heat receiving portion is pressed by the pressing unit toward the developing unit, and the holding member is provided with an engagement pin. The engaging pin of the holding member is engaged with the engaging hole of the support member that supports the holding member provided in the apparatus main body. The engaging hole includes a guide portion that extends in a direction inclined with respect to the mounting direction of the developing unit and a locking portion that extends in the mounting direction of the developing unit.

  The press contact of the heat receiving portion to the developing unit moves the holding member in the developing unit mounting direction after the developing unit is mounted on the apparatus main body. Then, the engaging pin of the holding member moves to the developing unit side while being guided by the guide portion of the engaging hole of the support member. Accordingly, the heat receiving portion held by the holding member moves to the developing unit side and comes into contact with the developing unit. Further, when the holding member is moved in the developing unit mounting direction, the heat receiving portion moves toward the back of the apparatus while sliding with the developing unit, and the heat receiving portion is pressed against the developing unit by the pressing means of the holding member. . When the engaging pin of the holding member moves to the locking portion, the heat receiving portion comes into contact with the developing unit with a predetermined pressing force.

  However, in the image forming apparatus described in Patent Document 1, when the heat receiving unit is brought into pressure contact with the developing unit as described above, the heat receiving unit slides on the developing unit. For this reason, the heat receiving portion may be rubbed due to sliding of the developing unit. When the heat receiving portion is rubbed, the adhesion between the heat receiving portion and the developing unit is lowered, which may reduce the cooling effect.

  The present invention has been made in view of the above background, and an object thereof is to provide an image forming apparatus capable of suppressing the occurrence of rubbing scratches on a heat receiving portion when the heat receiving portion is pressed against a developing unit. .

In order to achieve the above object, the invention of claim 1 includes a latent image carrier and a developer carrier that conveys the developer to a portion facing the latent image carrier, and is attached to and detached from the apparatus main body. a developing unit provided to be is installed so as to press the more wall surface of the developing unit to the elastic member, a cooling device having a heat receiving portion to the heat receiving heat from the developing unit by flowing a cooling medium therein, the A contact / separation mechanism configured to move the heat receiving portion in the mounting direction of the developing unit, so that the heat receiving portion moves from a separated position spaced from the developing unit to a pressure contacting position where the heat receiving portion is pressed against the wall surface of the developing unit. in the image forming apparatus, wherein the moving mechanism includes a holding member for holding the movable said heat receiving portion in a predetermined range in the vertical direction of the wall surface of the developing unit through the elastic member, the developing uni said retaining member And a support member for movably supporting the bets mounting direction, the holding member is provided with an engagement pin,
The support member includes an engagement hole that engages with the engagement pin, and the engagement hole is inclined with respect to the mounting direction of the developing unit, and the holding member is mounted together with the heat receiving portion on the developing unit. A guide portion that guides the engagement pin in a direction approaching the developing unit when moved in the direction, and moves the heat receiving portion held by the holding member from the separated position to the pressure contact position; An engaging portion that extends in parallel with the mounting direction of the unit and that engages the engaging pin in a state where the heat receiving portion is in pressure contact with the wall surface of the developing unit, and the guide portion includes the heat receiving portion After the contact with the wall surface of the developing unit, the holding member is moved relative to the heat receiving portion while guiding the engaging pin in a direction approaching the developing unit and compressing the elastic member. Moved to Te, wherein the heat receiving portion by the elastic member is configured so as to press the wall surface of the developing unit at a predetermined pressing force, wherein when mounting to the apparatus body of the developing unit, in contact with the developing unit, wherein and wherein the engaging pin of the holding member is provided with a heat receiving portion moving means for moving said holding member to said mounting direction for holding the developing unit integrally with the heat receiving portion to be positioned in the locking portion Is.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the heat receiving portion moving means is provided in the developing unit, and is provided in a protruding portion that protrudes toward the heat receiving portion, and the holding member . And a contact portion that contacts the protruding portion.
Further, the invention of claim 3, constituting the image forming apparatus according to claim 1 or 2, nears before Kigakaritome portion, the guide portion so that the inclination angle is small with respect to the mounting direction of the developing unit It is characterized by that.
According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the third aspect, wherein the guide portion has linear inclined portions having different inclination angles with respect to the mounting direction of the developing unit. The guide portion is configured such that the inclination angle of the inclined portion becomes smaller as it approaches.
According to a fifth aspect of the present invention, in the image forming apparatus of the third aspect, the guide portion is formed in a curved shape.
According to a sixth aspect of the invention, in the image forming apparatus of the fifth aspect, the guide portion is formed in a quadratic curve shape.
The invention of claim 7, in any one of the image forming apparatus according to claim 1乃 optimum 6, it is characterized in that a lubricant is applied to the contact portion between the engaging pin and the engaging hole.
According to an eighth aspect of the present invention, in the image forming apparatus according to any of the first to seventh aspects, the image forming apparatus further comprises positioning means for positioning the developing unit with respect to the latent image carrier, and the support member is attached to the developing unit. An engaging portion that engages with the engaged portion provided, and 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 on the elastic member causes the The engaging portion engages with the engaged portion, and the contact / separation mechanism is fixed to the developing unit.

  According to the present invention, the heat receiving portion can be brought into pressure contact with the wall surface of the developing unit while the heat receiving portion moves in the mounting direction together with the developing unit. As described above, when the heat receiving portion is moved in the mounting direction of the developing unit and brought close to the developing unit and the heat receiving portion is pressed against the wall surface of the developing unit, the developing unit is moved together with the heat receiving portion in the mounting direction. Therefore, the heat receiving portion does not slide on the wall surface of the developing unit. Therefore, it is possible to suppress the occurrence of sliding scratches on the heat receiving portion, and it is possible to suppress the decrease in the adhesion between the heat receiving portion and the developing unit. As a result, it is possible to suppress the cooling effect from decreasing over time.

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. FIG. 3 is a perspective view illustrating a state where the image forming unit is mounted on the apparatus main body. The expanded perspective view which shows the A section of FIG. FIG. 6 is a diagram for explaining the movement of the engagement pin and the movement of the contact portion when the image forming unit is attached to the apparatus main body. (A) is a figure explaining the force concerning an engagement pin in case the guide surface of a guide part is linear shape. (B) is a figure explaining the force concerning an engagement pin in case the guide surface of a guide part is curvilinear. The graph which investigated the load at the time of mounting | wearing of the developing unit 19K in the case of the guide part shown to Fig.26 (a), and the load at the time of mounting | wearing of the developing unit when a guide part is made into a quadratic curve. The figure which shows the modification of a guide part.

  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. Each of the photosensitive members 18Y, 18M, 18C, and 18K after the toner image is transferred is removed by the drum cleaning units 12Y, 12M, 12C, and 12K to remove the residual toner remaining on the photosensitive members 18Y, 18M, 18C, and 18K. Prepare for formation.

  In parallel with the toner image formation, paper is fed out from a paper feed storage unit (not shown) one by one 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 the image transfer is removed by the intermediate transfer belt cleaning unit 90 to remove residual toner remaining on the intermediate transfer belt 15 and prepare for another image formation.

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 where the exposure unit 9 is disposed and 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.

  Further, the first bent portion 41cK of the holding member 41K extends to the rear side of the apparatus with respect to the second bent portion 41dK, and the extended portion 41gK has a first engaged portion 191K of the developing unit 19K described later. It has a contact portion 41fK that contacts the back end. The contact portion 41fK is formed by bending, and has a surface orthogonal to the developing unit mounting direction.

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 an elastic member abutting portion 32eK of the heat receiving portion 32K, and the elastic member abutting portion 32eK of the heat receiving portion 32K is from the surface opposite to the pressure contact surface. Is also recessed toward the development unit. 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 has a guide portion 423aK that is inclined with respect to the longitudinal direction (developing unit insertion direction), and a locking portion 423bK that extends parallel to the longitudinal direction (developing unit insertion direction). doing. A part of the guide surface 423cK on which the engaging pin 140K of the guide portion 423aK moves in contact is curved. Further, grease as a lubricant is applied to the guide surface 423cK which is a contact portion of the engagement hole 423K with the engagement pin 140K, and friction when the engagement pin 140K moves in the engagement hole 423K. Lowering the resistance.

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. As a result, the support member 42K is fixed to the fixing member 50K so as to be able to swing in parallel with the pressing direction of the coil spring 142K, and is fixed so as not to move in the developing unit mounting direction. 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. FIG. 23 is a diagram for explaining a state in which the image forming unit 11K is mounted on the apparatus main body, and FIG. 24 is an enlarged perspective view showing a portion A of FIG. 23 and 24 show only a part of the case of the developing unit 19K in the image forming unit 11K for easy understanding.

  When the image forming unit 11K is attached to the apparatus main body by replacing the image forming unit 11K or the like, as shown in FIG. 24, the engaged portion as a protruding portion protruding toward the heat receiving portion 32K side of the developing unit 19K. The back end of the portion 191K contacts the contact portion 41fK provided on the holding member 41K. When the image forming unit 11K is further inserted from the state in which the rear end of the engaged portion 191K is in contact with the contact portion 41fK, the developing unit 19K causes the holding member 41K to be moved to the developing unit 19K. At the same time, it moves to the back of the device. Then, as shown in FIG. 25, the engagement pin 140K of the holding member 41K moves the guide portion 423aK of the engagement hole 423K. As a result, 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. That is, in the present embodiment, the contact portion 41f of the holding member 41K and the engaged portion 191K of the developing unit function as a heat receiving portion moving unit.

  Further, when the image forming unit 11K is attached to the apparatus main body, the holding member 41K moves toward the developing unit side while moving together with the developing unit 11K, and the heat receiving portion 32K contacts the side surface of the developing unit 19K. . At this time, the engagement pin 140K is located at the starting point A (see FIG. 18) of the curved portion of the guide surface 423cK. When the image forming unit 11K is further inserted into the apparatus main body from this state, the holding member 41K moves to the back side of the apparatus together with the developing unit 19K. Then, the engaging pin 140K is guided to the curved portion of the guide surface 423cK, the holding member 41K further approaches the developing unit side, and the heat receiving portion 32K presses the developing unit 19K. Then, when the holding member 41K moves to the back side of the apparatus together with the developing unit 19K and the engaging pin 140K is guided to the engaging portion 423bK of the engaging hole 423K as shown in FIG. The heat receiving portion 32K is in pressure contact with the side surface of the developing unit 19K.

  As described above, in the present embodiment, the holding member 41K moves to the back side of the apparatus together with the developing unit 19K, and presses the heat receiving portion 32K against the side surface of the developing unit 19K, so that the heat conducting sheet 130K of the heat receiving portion 32K and There is no rubbing with the developing unit 19K. As a result, the thermal conductive sheet 130K of the heat receiving portion 32K is not rubbed by the sliding with the developing unit 19K, and the thermal conductive sheet 130K can be well adhered to the side surface of the developing unit 19K without gaps over time. . As a result, the developing unit 19K can be cooled well over time.

  Further, when the heat receiving portion 32K presses the side surface of the developing unit, the engaged portions 191K and 192K of the developing unit 19K and the engaging portions 161K and 162K of the contacting / separating mechanism 40K are not in contact with each other. The reaction force from the unit 19K is transmitted from the heat receiving portion 32K to the support member 42K via the engagement pin 140K of the holding 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 portions 161K and 162K and the engaged portions 191K and 192K are engaged. . If the holding member 41K further moves to the rear side of the apparatus together with the developing unit 19K from this state, the support member 42K does not move in the direction away from the developing unit 19K even if it receives a reaction force from the developing unit 19K. Is compressed, and 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. 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.

  In the present embodiment, after the heat receiving portion 32K comes into contact with the side surface of the developing unit 19K, the engagement pin 140K moves while contacting the curved portion of the guide surface 423cK of the guide portion 423aK. Thereby, an increase in resistance when the developing unit 19K is mounted can be suppressed. That is, in the present embodiment, when the holding member 41K is moved in the mounting direction together with the developing unit 19K, the heat receiving portion 32K is pressed against the side surface of the developing unit 19K. Specifically, when the holding member 41 is guided by the guide portion 423aK of the engagement hole 423K and approaches the developing unit side 19K, the coil spring 142K is compressed and the developing unit 19K of the heat receiving portion 32K is compressed. The pressing force against increases. As a result, the reaction force applied to the engagement pin 140K also increases.

  As shown in FIG. 26 (a), when the guide surface 423cK of the guide portion 423aK is linear and the inclination angle with respect to the developing unit mounting direction is always constant, at the initial stage when the heat receiving portion 32K contacts the side surface of the developing unit 19K. The reaction force F1 applied to the engagement pin 140K is not so large, and the reaction force F1a applied when the engagement pin 140K is moved to the upper right in the drawing is not so large. When the image forming unit 11K is mounted together with the holding member 41 and the engagement pin 140K moves to the upper right in the figure, the coil spring 142K is compressed, and the reaction force applied to the engagement pin 140K at that time F2 increases more than F1. As a result, the drag force F2a applied when the engagement pin 140K at that time is moved to the upper right in the figure also increases compared to F1a. Therefore, if the frictional resistance is not considered, the insertion resistance of the image forming unit 11K increases by the drag (F2a-F1a).

  On the other hand, as shown in FIG. 26 (b), when the guide surface 423cK of the guide portion 423aK of the engagement hole 423K is curved, the angle of the tangent to the developing unit mounting direction approaches the locking portion 423bK. , Get smaller. Therefore, even if the holding member 41K comes close to the developing unit 19K, and the reaction force applied to the engaging pin 140K increases from F1 to F2, the drag F2a at that time, the heat receiving portion 32K contacts the developing unit 19K. It can be made almost the same as the initial drag F1a. As a result, if the frictional resistance is not considered, the insertion resistance of the image forming unit 11K can be made substantially constant from the initial time when the heat receiving portion 32K contacts the developing unit 19K.

  In particular, by making the curved shape a quadratic curve, the drag force applied when the engagement pin 140K moves the guide portion 423aK of the engagement hole 423K can always be constant, and when the image forming unit 11K is inserted. Such insertion resistance can be made constant.

  FIG. 27 shows the load when the developing unit 19K is mounted when the guide surface 423cK of the guide portion 423aK is linear as shown in FIG. 26A and the guide surface 423cK of the guide portion 423aK on a quadratic curve. It is the graph which investigated the load at the time of mounting | wearing of the developing unit 19K in the case of having carried out. FIG. 27 shows a simulation result on a computer where the frictional resistance between the guide surface 423cK and the engagement pin 140K is 0, and the mounting of the developing unit 19K is completed with the developing unit operation amount L.

  As shown in the straight line (A) of FIG. 27, when the guide surface 423cK of the guide portion 423aK is linear, the load when the developing unit 19K is inserted increases as the developing unit 19K is attached to the apparatus main body. I can see that On the other hand, as shown by the straight line (B) in FIG. 27, it is understood that the load when the developing unit 19K is inserted is always constant when the guide surface 423cK of the guide portion 423aK is a quadratic curve. When the guide surface 423cK of the guide portion 423aK is linear, the load immediately before the completion of the development unit setting reaches F, whereas the guide surface 423cK of the guide portion 423aK has a quadratic curve is half that It can be seen that the load of (F / 2) is suppressed. Thus, by making the guide surface 423cK of the guide portion 423aK a quadratic curve, the insertion resistance of the developing unit (image forming unit) can be suppressed, and a force is required when the developing unit (image forming unit) is mounted. Therefore, the developing unit (image forming unit) can be easily inserted, and usability can be improved.

  In practice, as shown in FIG. 26 (b), the vertical drag F2b increases and the frictional resistance increases as the inclination angle of the curve tangent to the developing unit mounting direction decreases. However, in this embodiment, grease as a lubricant is applied to the guide surface 423cK that is a contact portion of the engagement hole 423K with the engagement pin 140K, and the engagement pin 140K is placed in the engagement hole 423K. The frictional resistance when moving is lowered. Therefore, even if the vertical drag F2b increases, an increase in frictional resistance can be suppressed slightly, and an increase in insertion resistance of the image forming unit 11K can be suppressed.

  When taking out the image forming unit 11K from the apparatus main body, a lever (not shown) provided on the front side of the apparatus is operated to move the holding member 41K to the front side of the apparatus. When the holding member 41K moves to the front side of the apparatus, the image forming unit 11K (developing unit 19K) is pushed by the contact portion 41f, and the image forming unit 11K (developing unit 19K) moves together with the holding member 41K to the front side of the apparatus. . When the engaging pin 140K of the holding member 41K 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 relative to the support member 42K. To move away from the developing unit 19K. 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.

  In the above description, the guide surface 423cK of the guide portion 423aK of the engagement hole 423K is a quadratic curve. However, as shown in FIG. 28, the inclination angle of the guide portion 423aK of the engagement hole 423K with respect to the developing unit insertion direction is different. A plurality of linear inclined portions 423a-1 and 423a-2 may be provided, and the inclination angle θ2 of the inclined portion 423a-2 on the locking portion side may be smaller than the inclination angle θ1 of the inclined portion 423a-1. Even in the configuration as shown in FIG. 28, when the pressing force of the heat receiving portion 32 against the developing unit increases and the reaction force of the engagement pin 140K increases, the engagement pin 140K has a small inclination angle. Therefore, an increase in drag when moving the guide portion 423aK can be suppressed, and an increase in insertion resistance of the developing unit 19K can be suppressed. In the configuration shown in FIG. 28, only two inclined portions are provided, but two or more inclined portions may be provided. Also in this case, the inclination angle is made smaller as the inclined part is closer to the engaging part.

  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.

  As described above, according to the image forming apparatus of the present embodiment, the photosensitive member 18 that is a latent image carrier and the developing roller 19a that is a developer carrier that conveys the developer to a portion facing the photosensitive member 18 are provided. The developing unit 19 is detachably attached to the developing unit 19, and is installed so as to be pressed against the wall surface of the developing unit 19 by a coil spring 142 as a pressing means, and receives heat from the developing unit 19 by flowing a cooling medium therein. And a contact / separation mechanism 40 that moves the heat receiving portion 32 toward and away from the developing unit 19 by moving the heat receiving portion 32 in the mounting direction of the developing unit 19. When the developing unit 19 is mounted on the apparatus main body, a heat receiving portion moving means is provided that contacts the developing unit 19 and moves the heat receiving portion 32 in the mounting direction together with the developing unit 19. Thus, as described above, when the heat receiving portion is pressed against the developing unit 19, the heat receiving portion 32 moves in the developing unit mounting direction together with the developing unit 19, thereby preventing the heat receiving portion 32 from rubbing the developing unit. be able to. Thereby, it is possible to suppress the occurrence of rubbing scratches on the heat receiving portion 32, and the heat receiving portion 32 can be brought into close contact with the developing unit 19 without a gap over time. Thereby, the developing unit can be cooled well over time.

  The heat receiving portion moving means is provided in the developing unit 19 and is provided in the engaged portion 191 that protrudes toward the heat receiving portion 32, and the contact / separation mechanism 40 and is in contact with the engaged portion 191. 41f. Thereby, the engaged portion 191 of the developing unit 19 can move the heat receiving portion 32 together with the developing unit 19 in the mounting direction by pressing the contact portion 41f.

The contact / separation mechanism 40 includes a holding member 41 that holds the heat receiving portion 32 via the coil spring 142 and a support member 42 that supports the holding member 41 so as to be movable in the mounting direction of the developing unit 19. The holding member 41 includes an engagement pin 140, and the support member 41 includes an engagement hole 423 that engages with the engagement pin 140. The engagement hole 423 is inclined with respect to the mounting direction of the developing unit 19 and guides the engaging pin 140 in a direction in which the engaging pin 140 contacts and separates from the developing unit 19 while moving the engaging pin 140 in the developing unit mounting direction. The guide portion 423a has a locking portion 423b that extends parallel to the mounting direction of the front developing unit 19 and locks the engaging pin 140 when the heat receiving portion 32 is brought into pressure contact with the wall surface of the developing unit 19. Yes. Accordingly, by operating the holding member 41, the heat receiving portion 32 can be brought into and out of contact with the developing unit 19. It is possible to prevent the holding member 41 from being detached from the support member 42.
And the guide part 423a was comprised so that the inclination | tilt angle with respect to the mounting direction of the developing unit 19 became small as it approached the latching | locking part side. As a result, as described above, as the developing unit is mounted, even if the pressing force of the heat receiving portion 32 against the developing unit 19 increases and the reaction force of the pressing force on the engaging pin 140 increases, An increase in drag force when the pin 140 moves on the guide surface 423c of the guide portion 423a can be suppressed. Accordingly, it is possible to suppress an increase in resistance when the developing unit is mounted when the holding member 41 (heat receiving unit 32) is moved together with the developing unit to press the heat receiving unit 32 against the developing unit 19. Thus, the developing unit 19 can be mounted on the apparatus main body without applying a large force when the developing unit 19 is inserted into the apparatus main body. Therefore, the mounting operation of the developing unit 19 becomes easy, and usability can be improved.

  Specifically, as shown in FIG. 28, linear inclined portions 423a-1 and 423a-2 having different inclination angles with respect to the mounting direction of the developing unit are provided on the guide portion 423a, and the locking portion 423b side is provided. As approaching, the guide portion is configured so that the inclination angle of the inclined portion becomes smaller. As a result, the inclination angle with respect to the mounting direction of the developing unit 19 can be reduced as it approaches the locking portion side.

  As shown in FIG. 18, even if the guide portion is formed in a curved shape, the inclination angle with respect to the mounting direction of the developing unit 19 can be reduced as the guide portion is approached.

  In particular, by forming the guide portion in a quadratic curve, it is possible to make the resistance when the developing unit is mounted constant as shown in FIG.

  Further, by applying grease as a lubricant to the guide surface 423c that is a contact portion between the engagement hole 423 and the engagement pin 140, the frictional resistance between the engagement pin 140 and the guide surface 423c can be suppressed, and development is performed. The resistance when the unit is mounted can be further reduced.

  Further, a front positioning plate 111 and a back positioning plate 112 as positioning means for positioning the developing unit 19 with respect to the photoreceptor 18 are provided, and the contact / separation mechanism 40 includes engaged portions 191 and 192 provided in the developing unit 19. Engaging portions 161 and 162 are provided. When the heat receiving portion 32 is brought into pressure contact with the wall surface of the developing unit 19, the engaging portions 161 and 162 are engaged with the engaged portions 191 and 192 due to the reaction of the pressing force from the heat receiving portion 32 applied to the coil spring 142. Accordingly, the contact / separation mechanism 40 is fixed to the developing unit 19. Thereby, 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 on the coil spring can be exerted on the engaged portion of the developing unit. As a result, the pressing force applied from the heat receiving portion to the wall surface of the developing unit becomes an internal force, and the force caused by the pressing force from the heat receiving portion received by the positioning plate from the developing unit can be reduced. As a result, fluctuations in the gap between the photoconductor and the developing device can be suppressed.

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 111K: Front positioning plate 112K: Back positioning plate 130K: Thermal conduction sheet 140K: Engaging pin 141K, 150K: Step screw 142K: Coil spring 151K: Elastic member 161K: First engaging portion 162K : Second engaging portion 191K: first engaged portion 192K: second engaged portion 421: first member 421aK: back surface portion 421bK: support portion 421cK: fixing portion 421dK: mounting portion 421eK: slot 421fK: this Contact part 421gK: Extension part 422K: Second member 423K: Engagement hole 423aK: Guide part 423 -1: first inclined portion 423a-2: The second inclined portion 423BK: locking section 423CK: guide surface

JP 2011-18008 A

Claims (8)

A latent image carrier;
A developing unit having a developer carrying member that conveys the developer to a portion facing the latent image carrying member, and detachably attached to the apparatus main body;
Is installed so as to press the more wall surface of the developing unit to the elastic member, a cooling device having a heat receiving portion to the heat receiving heat from the developing unit by flowing a cooling medium therein,
A contact / separation mechanism configured to move the heat receiving portion in the mounting direction of the developing unit, so that the heat receiving portion moves from a separated position spaced from the developing unit to a pressure contacting position where the heat receiving portion is pressed against the wall surface of the developing unit ; In the provided image forming apparatus,
The contact / separation mechanism includes a holding member that holds the heat receiving portion movably in a predetermined range in a vertical direction of the wall surface of the developing unit via the elastic member;
A support member that supports the holding member so as to be movable in the mounting direction of the developing unit;
The holding member includes an engagement pin,
The support member includes an engagement hole that engages with the engagement pin,
The engaging hole is inclined with respect to the mounting direction of the developing unit, and when the holding member is moved in the developing unit mounting direction together with the heat receiving portion, the engaging pin is moved in a direction approaching the developing unit. A guide portion that guides and moves the heat receiving portion held by the holding member from the separated position to the press contact position; and extends in parallel with the mounting direction of the developing unit, the heat receiving portion of the developing unit In a state of being pressed against the wall surface, and having a locking portion that locks the engagement pin,
The guide portion guides the engaging pin in a direction approaching the developing unit and compresses the elastic member to compress the elastic member to the heat receiving portion even after the heat receiving portion contacts the wall surface of the developing unit. The heat receiving portion is configured to move relative to the developing unit side relative to the wall surface of the developing unit with a predetermined pressing force by the elastic member.
When the developing unit is mounted on the apparatus main body, the heat receiving unit is held integrally with the developing unit until the developing unit comes into contact with the developing unit and the engaging pin of the holding member is positioned at the locking portion. image forming apparatus characterized by a holding member provided with a heat receiving portion moving means for moving to the mounting direction. The image forming apparatus according to claim 1.
The heat receiving portion moving means includes a protruding portion provided in the developing unit and protruding toward the heat receiving portion, and an abutting portion provided in the holding member and contacting the protruding portion. Image forming apparatus. The image forming apparatus according to claim 1 or 2 ,
Nears before Kigakaritome side, the image forming apparatus characterized by the inclination angle with respect to the mounting direction of the developing unit is configured the guide portion to be smaller. The image forming apparatus according to claim 3.
The guide portion includes linear inclined portions having different inclination angles with respect to the mounting direction of the developing unit,
The image forming apparatus according to claim 1, wherein the guide portion is configured such that the inclination angle of the inclined portion becomes smaller as approaching the locking portion side. The image forming apparatus according to claim 3.
An image forming apparatus, wherein the guide portion is formed in a curved shape. The image forming apparatus according to claim 5.
An image forming apparatus, wherein the guide portion is formed in a quadratic curve shape. The image forming apparatus according to claim 1乃 Itaru 6,
An image forming apparatus, wherein a lubricant is applied to a contact portion between the engagement hole and the engagement pin. The image forming apparatus according to claim 1,
Positioning means for positioning the developing unit with respect to the latent image carrier;
The support member includes an engaging portion that engages with an engaged portion provided in the developing unit,
When the heat receiving portion is brought into pressure contact with the wall surface of the developing unit, the engaging portion engages with the engaged portion due to the reaction of the pressing force applied to the elastic member from the heat receiving portion. An image forming apparatus, wherein a separation mechanism is fixed to the developing unit.

Images