Image forming device

Abstract

To provide a configuration that can increase efficiency of cooling with a cooling duct 215 for cooling developer inside a developing device 4.SOLUTION: A developing device 4 can slide and move to a developing position and a separation position separated from a photoconductor drum 1 compared with the developing position. An air current flows inside a cooling duct 215 to cool developer inside the developing device 4. The cooling duct 215 has a duct wall 217 that is provided closer to an image forming apparatus body, a heat sink 409 that is provided closer to a developer container 400 and forms an air current space 215a between the duct wall 217 and the heat sink, and a plurality of ribs 412, 416 that is provided to project toward the inside of the air current space 215a from the heat sink 409. The duct wall 217 has an opposite surface 218a opposite to tips 412a of the plurality of ribs 412, 416, and a direction in which the developing device 4 slides and moves is a direction within ±10° with respect to the opposite surface 218a.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a copier, printer, facsimile, or a multifunction machine having multiple functions of these. [Background technology]

[0002] In an image forming apparatus, a toner image is formed by using a developing device to develop an electrostatic latent image formed on an image carrier such as a photosensitive drum. The developing device tends to increase the temperature of the developer contained therein because it agitates and transports the developer. Meanwhile, many image forming apparatuses have a configuration in which the developing device is detachable from the main body of the image forming apparatus for maintenance work, and a known configuration is one in which the developing device is rotatable between a developing position where the electrostatic latent image on the image carrier can be developed and a separate position away from the developing position.

[0003] In order to achieve both the suppression of the temperature rise of the developer and the detachable configuration of the developing device, a configuration has been proposed in which a cooling duct through which air flows is formed by the developing container and a developing tray provided in the image forming apparatus main body (Patent Document 1). In the configuration described in Patent Document 1, when the developing device is in the separated position, a part of the developing container is made to enter the air flow space inside the cooling duct. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-187738 Summary of the Invention [Problem to be solved by the invention]

[0005] To improve the cooling efficiency of the cooling duct, it is conceivable to provide multiple heat dissipation units protruding into the airflow space at the portion of the developer container that constitutes the cooling duct. This increases the surface area that comes into contact with the airflow within the cooling duct, thereby improving cooling efficiency. However, as in the configuration described in Patent Document 1, if part of the developer container is to intrude into the airflow space within the cooling duct when the developing device is in the separated position, it is necessary to increase the space between the multiple heat dissipation units and the developing tray so that the multiple heat dissipation units do not interfere with each other even in the separated position.

[0006] If the space between the heat dissipation units and the developing tray is increased in this way, the space between the heat dissipation units and the developing tray at the developing position will become even larger. In this case, the flow resistance of the space between the heat dissipation units and the developing tray will be significantly smaller than the flow resistance between the heat dissipation units themselves. This means that the flow rate of air flowing between the heat dissipation units will be lower than the flow rate of air flowing through this space. As a result, the heat dissipation efficiency from the heat dissipation units will decrease, and even if multiple heat dissipation units are installed, there is a risk that the cooling efficiency of the cooling duct will not be sufficiently improved.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a configuration that can improve the cooling efficiency of a cooling duct for cooling developer in a developing device. [Means for solving the problem]

[0008] One aspect of the present invention is an image forming apparatus including a developing device having an image carrier, a developer container containing a developer including toner and a carrier, and a developer carrier that carries the developer to develop an electrostatic latent image formed on the image carrier; an attachment section for attaching the developing device to the image forming apparatus; a movement mechanism that moves the developing device attached to the attachment section from a spaced position that is spaced apart from the image carrier with respect to a development position where an electrostatic latent image formed on the image carrier is developed to the development position; a cover member that is provided along an attachment direction in which the developing device is attached to the attachment section, and is attached to the developing container to cover the developing container; and a wall member that is provided along the attachment direction, and that does not move together with the developing device when the developing device is moved from the spaced position to the development position by the movement mechanism. and a fan for generating an airflow to cool the developing device, wherein when the developing device is in the separated position, neither the first seal member nor the second seal member contacts the wall member, and when the developing device is in the developing position, both the first seal member and the second seal member contact the wall member, and when the developing device is in the developing position, a space for the airflow generated by the fan to pass through is formed along the mounting direction by the cover member, the wall member, the first seal member, and the second seal member. One aspect of the present invention is an image forming apparatus including a developing device having an image carrier, a developer container containing a developer including toner and a carrier, and a developer carrier that carries the developer to develop an electrostatic latent image formed on the image carrier; an attachment section for attaching the developing device to the image forming apparatus; a moving mechanism that moves the developing device attached to the attachment section from a spaced position that is spaced apart from the image carrier with respect to a development position where the electrostatic latent image formed on the image carrier is developed to the development position; and a moving mechanism that is provided along an attachment direction for attaching the developing device to the attachment section, and moves the developing device to the attachment section along an attachment direction for attaching the developing device to the attachment section, and moves the developing container Topa cover member attached to the developing device to cover the developing container; a wall member provided along the mounting direction, the wall member not moving together with the developing device when the developing device is moved from the separated position to the developing position by the moving mechanism; a seal member attached to the cover member; and a fan for generating an air flow to cool the developing device, wherein when the developing device is at the developing position, The wall member is located vertically above the cover member, and The image forming apparatus is characterized in that a space through which the airflow from the fan passes is formed along the mounting direction by the cover member, the wall member, and the sealing member. One aspect of the present invention is an image forming apparatus including a developing device having an image carrier, a developer container containing a developer including toner and a carrier, and a developer carrier that carries the developer to develop an electrostatic latent image formed on the image carrier; an attachment portion for attaching the developing device to the image forming apparatus; a moving mechanism that moves the developing device attached to the attachment portion from a spaced position that is spaced apart from the image carrier with respect to a development position where the electrostatic latent image formed on the image carrier is developed to the development position; a cover member that is provided in the attachment portion along an attachment direction in which the developing device is attached to the attachment portion, and is attached to the developing container to cover the developing container; The image forming apparatus comprises a wall member arranged along the mounting direction, the wall member not moving with the developing device when the developing device is moved from the separated position to the developing position by the moving mechanism, a sealing member attached to the cover member, and a fan for generating an air flow to cool the developing device, wherein the thermal conductivity of the sealing member is higher than the thermal conductivity of the developing container, and when the developing device is in the developing position, a space for the air flow generated by the fan to pass through is formed along the mounting direction by the cover member, the wall member, and the sealing member. [Effects of the Invention]

[0009] According to the present invention, the cooling efficiency of the cooling duct for cooling the developer in the developing device can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a front view of an image forming unit according to the embodiment. [Figure 3] FIG. 2 is a cross-sectional view of an image forming unit according to the embodiment. [Figure 4] FIG. 4 is a bottom view of the cooling duct according to the embodiment. [Figure 5] FIG. 2 is a cross-sectional view of a developing device according to the embodiment. [Figure 6] FIG. 3 is a block diagram showing a control configuration for an air supply fan according to the embodiment. [Figure 7] 5 is a flowchart of control of an air supply fan according to the embodiment. [Figure 8] FIG. 3 is a cross-sectional view of the developing device in the separated position according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The embodiment will be described with reference to Figures 1 to 8. First, the schematic configuration of the image forming apparatus of the present embodiment will be described.

[0012] [Image forming equipment] Fig. 1 is a schematic cross-sectional view showing an example of an image forming apparatus according to this embodiment. The image forming apparatus 100 shown in Fig. 1 is an electrophotographic full-color laser printer. The image forming apparatus 100 forms four different color toner images through the processes of charging, exposing, developing, and transferring using first, second, third, and fourth image forming units Py, Pm, Pc, and Pb arranged side by side inside an image forming apparatus main body 101.

[0013] The control unit 19 has a CPU and memories such as ROM and RAM. When a print command signal is input from an external interface such as a host computer, the control unit 19 sequentially operates the image forming units Py, Pm, Pc, and Pb in accordance with an image formation control sequence stored in the memory.

[0014] In each of the image forming stations Py, Pm, Pc, and Pb, a photosensitive drum 1 serving as an image carrier rotates at a predetermined peripheral speed (process speed). An intermediate transfer belt 7, stretched across a drive roller 6a, a driven roller 6b, and a tension roller 6c, is rotated by the drive roller 6a at a peripheral speed corresponding to the rotational peripheral speed of each photosensitive drum 1 so as to straddle the photosensitive drums 1 of the image forming stations Py, Pm, Pc, and Pb. In the image forming station Py for the first color, yellow, the outer peripheral surface (surface) of the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a charger 2. Next, an exposure device 3 scans and exposes a laser beam generated based on image information from an external device onto the charged surface of the photosensitive drum 1. This forms an electrostatic latent image corresponding to the image information on the charged surface of the photosensitive drum 1.

[0015] The electrostatic latent image formed on the photosensitive drum 1 is developed by the developing device 4 using yellow toner (developer), and a yellow toner image (developed image) is formed on the surface of the photosensitive drum 1. When the toner (developer) in the developing device 4 is consumed, toner (developer) is replenished from a replenishment device 20y. Similar charging, exposure, and development processes are also performed in the image forming unit Pm for the second color, magenta, the image forming unit Pc for the third color, cyan, and the image forming unit Pb for the fourth color, black.

[0016] The toner images of each color formed on the surface of the photosensitive drum 1 at each image forming station Py, Pm, Pc, and Pb are transferred in succession onto the outer circumferential surface (surface) of the intermediate transfer belt 7 by a primary transfer roller (transfer member) 8 arranged opposite the photosensitive drum 1 with the intermediate transfer belt 7 in between. This forms a full-color toner image on the surface of the intermediate transfer belt 7. After the toner image transfer, the photosensitive drum 1 has residual toner remaining on its surface removed by a drum cleaner 5, and is then ready for the next image formation.

[0017] Meanwhile, recording material P is conveyed from a feeding cassette 10 by a delivery roller 11 through a conveying path 12a to registration rollers 13. The recording material P is, for example, a sheet material such as paper or a plastic sheet. Next, the recording material P is conveyed by the registration rollers 13 to a secondary transfer nip portion Tn between the intermediate transfer belt 7 and a secondary transfer roller 14. The recording material P is then nipped and conveyed at this secondary transfer nip portion Tn, and during this conveying process, the toner image on the surface of the intermediate transfer belt 7 is transferred onto the recording material P by the secondary transfer roller 14. After the toner image has been transferred, residual toner remaining on the surface of the intermediate transfer belt 7 is removed by a belt cleaner 9, and the intermediate transfer belt 7 is then used for the next image formation.

[0018] The recording material P carrying an unfixed toner image is introduced into the nip portion of the fixing device 15 with the image-carrying surface facing up. The recording material P is then sandwiched and conveyed through the nip portion of the fixing device 15, whereby the toner image is heated and fixed onto the recording material P. When an image is formed on only one side of the recording material P, the recording material P discharged from the fixing device 15 is switched by a switching member 16 to pass through a discharge roller 17 and onto a discharge tray 18 provided on the side of the image forming apparatus main body 101.

[0019] When images are to be formed on both sides of the recording material P, the recording material P discharged from the fixing device 15 is guided downward to the reverse conveying path 12b by a switching member 16. In the reverse conveying path 12b, when the trailing edge of the recording material P reaches the reversing point Rp, the recording material P is switched back so that the image-bearing surface faces up, and in that state is sent to the double-sided conveying path 12c. In the double-sided conveying path 12c, the recording material P is conveyed to the registration rollers 13 through the conveying path 12a. The recording material P is conveyed by the registration rollers 13 to the secondary transfer nip portion Tn, where it is sandwiched and conveyed. During this conveying process, the toner on the surface of the intermediate transfer belt 7 is transferred onto the recording material P by the secondary transfer roller 14.

[0020] The recording material P carrying an unfixed toner image is introduced into the nip portion of the fixing device 15 with the image-carrying surface facing up. The recording material P is then sandwiched and conveyed through the nip portion of the fixing device 15, whereby the toner image is heated and fixed onto the recording material P. The recording material P discharged from the fixing device 15 is then discharged onto a discharge tray 18 via a switching member 16 and discharge rollers 17.

[0021] An air intake port 212 is provided at the top of the image forming apparatus main body 101, and air is sent from the outside into an air intake duct 210 by an air intake fan 211. The air intake duct 210 is connected to a cooling duct 215 that directs airflow into the image forming units Py, Pm, Pc, and Pb through a connection port 214 located in front of the image forming units Py, Pm, Pc, and Pb, and introduces cooling airflow into the developing devices 4 in each image forming unit Py, Pm, Pc, and Pb. The airflow that cools the image forming units Py, Pm, Pc, and Pb cools the electrical components located behind the image forming apparatus main body 101 and is then exhausted to the outside of the image forming apparatus 100 through an exhaust port (not shown) by an exhaust fan 213. The front side of the image forming apparatus 100 is the side where an operator operates the image forming apparatus 100, and in this embodiment, this is the side where the developing devices 4 and other components are replaced. The rear side is the rear side of the image forming apparatus 100.

[0022] Duct Run Next, the duct path passing through the image forming units Py, Pm, Pc, and Pb will be described. In this embodiment, the image forming unit Py will be described, but the image forming units Py, Pm, Pc, and Pb have the same internal layout, except for the color of the developer. FIG. 2 shows a schematic diagram of the front side of the image forming unit Py. A connection port 214 of a cooling duct 215 is located in front of the image forming unit Py, and the connection port 214 connects to the air intake duct 210. The connection between the air intake duct 210 and the cooling duct 215 allows the air flow 216 in the air intake duct 210 to be introduced into the cooling duct 215.

[0023] 3 shows a schematic cross-sectional view of the image forming unit Py. The photosensitive drum 1 rotates counterclockwise, and the charger 2 is disposed above it and the developing device 4 is disposed on the left side. The developing device 4 has a pressure member on the surface opposite to the surface facing the photosensitive drum 1. (moving mechanism) 40 is arranged, and by pressing the developing device 4 toward the photosensitive drum 1, the photosensitive drum 1 and the developing device 4 are arranged to maintain a predetermined distance. An intermediate transfer belt 7 is arranged below the photosensitive drum 1, and a drum cleaner 5 is arranged on the right side. A cooling duct 215 for cooling the developing device 4 is formed above the developing device 4, and the developer in the developing device 4 is cooled by flowing airflow 216 supplied from an air intake port 212 into the duct.

[0024] 4 shows a schematic bottom view of the cooling duct 215. The cooling duct 215 is connected to the air intake duct 210 provided in the image forming apparatus main body 101 at a connection port 214 in front of the image forming unit Py, and guides airflow to the upper part of the developing device 4. The cooling duct 215 is divided into a duct wall 217 and a heat sink 409 above the developing device 4. The duct wall 217 on the image forming apparatus main body side forms the upper side of the cooling duct 215, and the developing device 4 is connected to the image forming apparatus main body 101. Mounting part When the developing device 4 is mounted on the developing device 4 and is ready for image formation, a heat sink 409 arranged on the upper part of the developing device 4 forms the lower side of the duct. Downstream of the upper part of the developing device 4 in the direction of flow of the air current 216, the cooling duct 215 is again connected to a connection duct 220 provided in the image forming apparatus main body 101. The connection duct 220 is then connected to an electrical component arranged at the rear inside the apparatus main body. The detailed configuration of the cooling duct 215 will be described later.

[0025] [Developing device] Next, the developing device 4 will be described. A schematic cross-sectional view of the developing device and its surroundings is shown in FIG. 5. The developing device 4 is located in the image forming apparatus main body 101 (FIG. 1). Mounting part Specifically, the developing device 4 is detachably mounted on the image forming apparatus main body 101. Mounting part 1. The developing device 4 can be inserted into and removed from the photosensitive drum 1 in the direction of arrow A shown in FIG. 5. That is, the developing device 4 can slide relative to the image forming apparatus main body 101 between a developing position where it can develop an electrostatic latent image formed on the photosensitive drum 1 by a first developing roller 404 and a second developing roller 405 (described later) and a separated position where it is further away from the photosensitive drum 1 than the developing position and where the developing device 4 can be attached to and detached from the image forming apparatus main body 101.

[0026] Specifically, when the developing device 4 is removed from the image forming apparatus main body 101, the developing device 4 is slid in the direction of arrow A from the photosensitive drum 1 to the separated position. The sliding direction of the developing device 4 is a direction perpendicular to the rotation axis direction of the photosensitive drum 1, and in this embodiment, is a direction along the transfer surface of the intermediate transfer belt 7, which is stretched between the drive roller 6a and tension roller 6c, and onto which the toner image is transferred from the photosensitive drum 1.

[0027] On the other hand, when the developing device 4 is inserted into the image forming apparatus main body 101 and attached to a predetermined position, the developing device 4 is moved in the direction opposite to the direction of arrow A to be positioned at a developing position (pressure position) where the first developing roller 404 and the second developing roller 405 face the photosensitive drum 1 with a predetermined gap therebetween. At this time, the developing device 4 is pressed toward the photosensitive drum 1 by a pressure member 40 such as a spring, and a part of the developing device 4 comes into contact with a part on the photosensitive drum 1 side, thereby maintaining the above-mentioned gap at an appropriate size.

[0028] In an embodiment in which flanges are provided at both longitudinal ends of the photosensitive drum 1, for example, abutting rollers provided at both longitudinal ends of the first developing roller 404 and the second developing roller 405 are abutted against the flanges provided at both longitudinal ends of the photosensitive drum 1. This maintains the above-mentioned gap at an appropriate size.

[0029] On the other hand, in an embodiment in which flanges are not provided at both longitudinal ends of the photosensitive drum 1, for example, abutting rollers provided at both longitudinal ends of the first developing roller 404 and the second developing roller 405 are abutted against the bare tube of the photosensitive drum 1. This maintains the above-mentioned gap at an appropriate size.

[0030] The developing device 4 develops the electrostatic latent image formed on the photosensitive drum 1 with a developer containing toner and a carrier. The developer in this embodiment is a so-called two-component developer containing non-magnetic toner and a magnetic carrier. The developing device 4 includes a developer container 400 as a housing that contains the developer therein, and supports the rotation of a first screw 401, a second screw 402, and a third screw 403 that are disposed inside the developer container. The first screw 401, the second screw 402, and the third screw 403 as transport members agitate and transport the developer inside the developer container 400.

[0031] A first developing roller 404 as a developer carrier and a first developing roller 405 as a second developing roller are rotatably supported on the surface of the developing container 400 facing the photosensitive drum 1. The second developing roller 405 is located below the first developing roller 404 and is arranged in parallel with the first developing roller 404 with a predetermined gap therebetween.

[0032] The first developing roller 404 and the second developing roller 405 are each formed in a cylindrical shape, and a magnet is disposed therein so as not to rotate. The first developing roller 404 and the second developing roller 405 are each driven to rotate in the direction of the arrow shown in FIG. 5, and carry and transport developer by the magnetic attraction force of the magnet. In addition, a developing blade 407 serving as a regulating member is fixed at a predetermined distance from the first developing roller 404 at a position upstream of the surface of the first developing roller 404 facing the photosensitive drum. The developing blade 407 regulates the layer thickness of the developer carried on the first developing roller 404.

[0033] The developing container 400 is partitioned by a horizontally extending partition wall 400c into an upper developing chamber (developer transport path) 400a as a first chamber, and an agitating chamber (developer transport path) 400b located below the developing chamber 400a as a second chamber. The developing chamber 400a is a functional chamber that supplies developer to the first developing roller 404. The agitating chamber 400b is a functional chamber that receives and agitates recovered developer recovered from the second developing roller 405, excess developer that was not supplied to the first developing roller 404 in the developing chamber 400a, and replenishment developer replenished from outside the developing device 4.

[0034] The developing chamber 400a and the stirring chamber 400b are respectively provided with a first screw 401, a second screw 402, and a third screw 403. The first screw 401, the second screw 402, and the third screw 403 are all screw members with spiral blades on rotation axes that are arranged substantially parallel to the rotation axis directions (longitudinal directions) of the first developing roller 404 and the second developing roller 405.

[0035] At both longitudinal end portions of the partition wall 400c, a first communication portion and a second communication portion are provided, which are transfer portions (developer transport paths) that transport developer between the developing chamber 400a and the stirring chamber 400b. The first screw 401 and the second screw 402 transport developer in opposite directions. The developer moves from the stirring chamber 400b to the developing chamber 400a through the first communication portion, and from the developing chamber 400a to the stirring chamber 400b through the second communication portion, thereby forming a developer circulation path.

[0036] The developer transported by the second screw 402 and the first screw 401 is transported along the surface of the first developing roller 404 and is limited to a predetermined thickness by the developing blade 407. Then, at a development position facing the photosensitive drum 1, the developer develops the electrostatic latent image formed on the surface of the photosensitive drum 1. The developer remaining on the first developing roller 404 is transported by the first developing roller 404, then handed over to the second developing roller 405, and transported along the surface of the second developing roller 405. After that, it is collected into the developing container 400 between the second developing roller 405 and the collection roller 406. The developer collected in the developing container 400 is stirred and transported by the third screw 403 and the second screw 402, and is transported to the first screw 401. A temperature sensor 408 is disposed below the developing container 400 at a position facing the developer stirred and transported by the second screw 402, and detects the temperature of the developer in the developing container.

[0037] [Cooling duct] In recent years, there has been a demand for both an increase in the process speed and a reduction in size of the image forming apparatus 100. When the process speed of the image forming apparatus 100 is increased, the drive speed of each component, such as the developer transport speed within the developing device 4, increases, which makes it easier for the temperature of the developer within the developing device 4 to rise. Furthermore, when the image forming apparatus 100 is made smaller, the space for dissipating heat generated within the image forming apparatus main body 101 becomes narrower, further making it easier for the temperature of the developer to rise. Therefore, in this embodiment, as described above, a cooling duct 215 through which air flows to cool the developer is provided above the developing device 4.

[0038] 5, the cooling duct 215 has a duct wall 217, a heat sink 409, and a plurality of ribs 412 and 416. The duct wall as a main body side wall (Wall components)The duct wall 217 is provided on the image forming apparatus main body side and does not move even when the developing device 4 moves between the developing position (pressure position) and the separated position. The duct wall 217 is arranged along the attachment / detachment direction of the developing device 4, which in this embodiment is the front-rear direction of the image forming apparatus 100. The duct wall 217 may be made of the same material as the heat sink 409 or a different material. Furthermore, the duct wall 217 is preferably made of a material having a higher thermal conductivity than the developing container 400. In this embodiment, the duct wall 217 is made of a metal such as an aluminum alloy, but may also be made of a resin having a high thermal conductivity, similar to the heat sink 409 described below. The duct wall 217 also has a top surface portion 218 as an opposing wall portion, a joint wall 219a as a protruding wall portion or a first wall portion on the main body side, and a joint wall 219b as a second wall portion on the main body side.

[0039] On the other hand, the heat sink as the developing side wall (Cover member) Heat sink 409 is provided on the developer container side, and forms airflow space 215a through which airflow flows between it and duct wall 217. Like duct wall 217, heat sink 409 is arranged along the attachment / detachment direction of developing device 4. Heat sink 409 also has a contact wall portion 410, a side wall 414a as a developer-side first wall portion, and a side wall 414b as a developer-side second wall portion.

[0040] A plurality of ribs 412, 416 serving as a plurality of heat dissipation portions are provided so as to protrude from the heat sink 409 into the airflow space. The plurality of ribs 412, 416 are arranged along the direction in which the airflow 216 flows inside the cooling duct 215, and more specifically, like the duct wall 217, they are arranged along the attachment / detachment direction of the developing device 4.

[0041] Joining walls 219a, 219b of duct wall 217 join side walls 414a, 414b of heat sink 409 to form cooling duct 215, through which airflow 216 can pass, between duct wall 217 and heat sink 409. Furthermore, a plurality of ribs 412, 416 are arranged in airflow space 215a inside cooling duct 215 along the flow direction of airflow 216.

[0042] The cooling duct 215 will be described in more detail. As described above, a heat sink 409 made of a material with a higher thermal conductivity than the developing container 400 is disposed above the developing device 4. In this embodiment, the heat sink 409 also functions as a top cover that covers the upper part of the developing container 400, and is disposed above the developing chamber 400a in the longitudinal direction. For example, the developing container 400 is made of PC+ABS (polycarbonate-acrylonitrile-butadiene-styrene mixture) resin, and the heat sink 409 is made of an aluminum alloy. Note that the heat sink 409 may be made of other metals, such as copper, or a resin material with a high thermal conductivity, other than the aluminum alloy, as long as the heat conductivity is higher than that of the developing container 400.

[0043] The heat sink 409 has a contact wall portion 410 having a contact surface 410a that can come into contact with the developer in the developing container 400. A plurality of ribs 412, 416 are provided so as to protrude from a heat dissipation surface 410b, which is the surface of the contact wall portion 410 opposite the contact surface 410a. Meanwhile, the top surface portion 218 of the duct wall 217 has an opposing surface 218a that faces the tips 412a of the plurality of ribs 412, 416. In this embodiment, the opposing surface 218a and the heat dissipation surface 410b are substantially parallel to each other and also to the direction in which the developing device 4 slides between the development position and the separated position. Note that "substantially parallel" means that the relative angle is within ±10°, more preferably within ±5°, and this also applies to the following cases.

[0044] Furthermore, as described above, the duct wall 217 has connecting walls 219a and 219b. When the direction in which the developing device 4 slides from the development position to the separated position is defined as a predetermined direction (the direction of arrow A in FIG. 5), the connecting wall 219a protrudes from the downstream end of the top surface 218 in the predetermined direction toward the heat sink 409 (the side of the development side wall). The connecting wall 219b protrudes from the upstream end of the top surface 218 in the predetermined direction toward the heat sink 409. The connecting walls 219a and 219b are substantially parallel to each other and are disposed at a substantially right angle to the opposing surface 218a. The term "substantially right angle" means that the angle between one direction and the other is within 90°±10°, more preferably within ±5°, and this also applies to the following cases.

[0045] On the other hand, the heat sink 409 has side walls 414a and 414b as described above. The side wall 414a is disposed downstream of the joining wall 219a in the predetermined direction, and is joined to the joining wall 219a to close the downstream side of the airflow space 215a in the predetermined direction. The side wall 414b is disposed downstream of the joining wall 219b in the predetermined direction, and is joined to the joining wall 219b to close the upstream side of the airflow space 215a in the predetermined direction. In this embodiment, the joining wall 219a and the side wall (First Rib) 414a is joined via a first seal member 415a, and the joining wall 219b and the side wall (Second rib) It is joined to 414b via a second seal member 415b.

[0046] The first seal member 415a and the second seal member 415b are each made of a flexible elastic material or the like, and are arranged in an elastically compressed state between the joining wall 219a and the side wall 414a, and between the joining wall 219b and the side wall 414b at the development position, thereby sealing the upstream and downstream sides of the airflow space 215a in a predetermined direction.

[0047] The first seal member 415a and the second seal member 415b are preferably made of a material with high thermal conductivity relative to the developing container 400. Examples of such seal members include gaskets used for electromagnetic wave shielding. This gasket has a metal mesh wrapped around the outside of a sponge-like material, resulting in good thermal conductivity. The seal members themselves may also be made of a highly thermally conductive material similar to silicone grease. Configuring the first seal member 415a and the second seal member 415b in this manner allows heat to be transferred from the heat sink 409 to the duct wall 217 by thermal conduction. This allows heat to be dissipated not only by the heat sink 409 but also by the duct wall 217, thereby enabling more efficient cooling of the developer.

[0048] The downstream end of the contact wall portion 410 of the heat sink 409 in the predetermined direction is bent toward the duct wall 217 and further bent downstream in the predetermined direction to form a bent portion 413a. A first seal member 415a is disposed on the bent portion 413a. Meanwhile, of the multiple ribs 412, 416, the rib 412 located most upstream in the predetermined direction is provided with a protruding portion 413b that protrudes upstream in the predetermined direction, and a side wall 414b is formed at the tip of the protruding portion 413b. A support member 407a that supports the developing blade 407 is fixed to the protruding portion 413b, and a second seal member 415b is disposed on the support member 407a.

[0049] Furthermore, a heat dissipation protrusion 411 is provided at the upstream end of the contact wall 410 of the heat sink 409 in the predetermined direction, protruding further upstream in the predetermined direction. The heat dissipation protrusion 411 protrudes from the contact wall 410 toward a space upstream of the developing blade 407 in the rotation direction of the first developing roller 404. This space is the space before the developer carried by the first developing roller 404 enters the developing blade 407, and serves as a developer reservoir where the developer accumulates. By positioning the heat dissipation protrusion 411, which is part of the heat sink 409, in the developer reservoir upstream of the developing blade 407, the heat of the developer before entering the developing blade 407 can be released toward the heat sink 409. As a result, the developer can be efficiently cooled before entering the developing blade 407.

[0050] In the present embodiment, in addition to the heat dissipation protrusion 411 described above, a contact surface 410a of the heat sink 409 facing the inside of the developing container 400 comes into contact with the developer transported from the first screw 401 toward the developing roller 404 above the first screw 401, thereby exchanging heat. Also, considering the longitudinal direction of the developing device 4, about half of the longitudinal direction of the developing chamber 400a has a height such that the developer surface comes into contact with the contact surface 410a, and therefore the developer in that portion also comes into contact with the contact surface 410a, thereby exchanging heat. Note that in this embodiment, the heat sink 409 is disposed above the developing container 400, and therefore the contact state with the developer is as described above, but the arrangement of the heat sink is not limited to this, and the heat sink 409 may be disposed so that the entire contact surface of the heat sink comes into contact with the developer.

[0051] In either case, the heat received from the developer in this manner is transferred by thermal conduction to the heat dissipation surface 410b of the heat sink 409 facing the outside of the developer container, and as described above, heat exchange occurs with the airflow 216 that is introduced from outside the image forming apparatus main body 101 and flows through the cooling duct 215. A plurality of ribs 412, 416 are arranged on the heat dissipation surface 410b of the heat sink 409 to increase the surface area, and air is allowed to flow between the ribs 412, 416 to increase the efficiency of heat exchange. In this way, in this embodiment, heat exchange occurs between the heat sink 409 and the airflow that flows through the cooling duct 215, thereby efficiently cooling the developer in the developer container.

[0052] [Air supply fan control] Next, the control of the intake fan 211 that sends air into the cooling duct 215 will be described with reference to FIGS. 6 and 7. As shown in FIG. 6, the intake fan 211 is controlled by the control unit 19 based on a signal from a temperature sensor 408 provided in the developing device 4 of each image forming unit Py, Pm, Pc, and Pb. When the temperature of the developer is lower than a predetermined temperature, the intake fan 211 rotates at a low speed. However, when the temperature sensor 408 detects the temperature of the developer in the developing device 4 and the temperature exceeds the predetermined temperature, the control unit 19 instructs the intake fan 211 to change its rotation speed and rotate it at a high speed in order to increase the cooling capacity and prevent the temperature of the developer in the developing device 4 from becoming too high.

[0053] 7 shows a flowchart for driving air intake fan 211 of image forming apparatus 100. First, control unit 19 detects the temperature of the developer in developing device 4 using temperature sensor 408 (S101). Then, control unit 19 determines whether the temperature detected by temperature sensor 408 satisfies a predetermined temperature, i.e., whether the temperature is equal to or lower than the predetermined temperature (S102). If the temperature is equal to or lower than the predetermined temperature in S102, the rotation speed of air intake fan 211 is not changed to a high speed (i.e., it remains at a low speed, S103), and the flow ends. If the temperature is higher than the predetermined temperature in S102, the rotation speed of air intake fan 211 is changed to a high speed (S104), and the flow ends.

[0054] [Installing and removing the developing unit] As described above, in this embodiment, the air intake fan 211 sends air into the cooling duct 215 to cool the developer in the developing device 4. When the developing device 4 is attached to or detached from the image forming apparatus main body 101, it moves to the separated position as described above to prevent interference with the photosensitive drum 1. Conventionally, this movement to the separated position has been achieved by rotating the developing device. In a configuration in which the cooling duct is divided into the developing device side and the image forming apparatus main body side, as in this embodiment, it was necessary to increase the space between the ribs, which serve as heat dissipation sections, and the duct wall facing the ribs to prevent interference between the ribs and the duct wall due to rotation of the developing device. With this configuration, the flow resistance between the ribs increases relative to the space, making it difficult to sufficiently increase cooling efficiency.

[0055] It is also possible to configure the developing device so that it moves to the opposite side of the duct when rotated. That is, it is possible to specify the positional relationship between the developing device and the duct wall so that the space between the rib and the duct wall increases when the developing device moves to the separated position. However, in this configuration, it is necessary to provide a space separate from the duct wall for the developing device to retreat. This reduces space efficiency and leads to an increase in the size of the image forming apparatus body.

[0056] Therefore, in this embodiment, the direction in which the developing device 4 moves between the development position and the separated position is a sliding direction, not a rotation direction. The sliding direction of the developing device 4 is within ±10°, preferably within ±5°, of the opposing surface 218a of the duct wall 217. That is, the developing device 4 moves approximately parallel to the opposing surface 218a. This prevents interference between the duct wall 217 on the image forming apparatus main body 101 side and the multiple ribs 412 and 416 of the heat sink 409 that move together with the developing device 4 when the developing device 4 moves to the separated position, and also suppresses changes in the distance between the multiple ribs 412 and 416 and the opposing surface 218a of the duct wall 217.

[0057] The direction in which the developing device 4 slides is within 90°±10°, preferably 90°±5°, relative to the direction in which the ribs 412 and 416 protrude. That is, the developing device 4 moves in a direction substantially perpendicular to the direction in which the ribs 412 and 416 protrude. The ribs 412 and 416 are parallel to each other and protrude from the heat dissipation surface 410b of the contact wall portion 410 at a substantially perpendicular angle to the heat dissipation surface 410b. The heat dissipation surface 410b and the opposing surface 218a are also substantially parallel. Therefore, even if the distance between the tips 412a of the ribs 412 and 416 and the opposing surface 218a is narrowed, interference between the ribs 412 and 416 and the opposing surface 218a due to the movement of the developing device 4 can be prevented.

[0058] Furthermore, the distance between the tip 412a of at least one of the ribs 412, 416, and the opposing surface 218a is shorter than the distance between the tip 412a of the rib 412 and the heat dissipation surface 410b. It is preferable that all of the ribs 412, 416 have such lengths. This ensures that the flow path resistance of the space formed between the ribs 412, 416 is smaller than the flow path resistance of the space formed between the tip 412a of the ribs 412, 416 and the opposing surface 218a, or does not become too large. This allows the airflow 216 passing through the cooling duct 215 to pass evenly between the ribs 412, 416, thereby improving the heat exchange efficiency between the heat sink 409 and the airflow 216.

[0059] Next, the operation when removing the developing device 4 from the image forming apparatus main body 101 will be described. When forming an image, the developing device 4 is pressed against the photosensitive drum 1 and is located at a developing position (pressure position) adjacent to the photosensitive drum 1 at a predetermined distance, as shown in FIG. 5. On the other hand, when removing the developing device 4 from the image forming apparatus main body 101 for maintenance or the like, the pressure on the developing device 4 is released to move the developing device 4 to a separated position away from the photosensitive drum 1, and then the developing device 4 can be pulled out toward the front of the main body, making it possible to remove the developing device from the image forming apparatus main body 101. FIG. 8 shows the developing device 4 in the separated position.

[0060] 5, in the pressurized position, duct wall 217 forms the upper side of cooling duct 215. Duct wall 217 forms top surface portion 218 and joining walls 219a, 219b extending downward from top surface portion 218. Side walls 414a, 414b of heat sink 409 are joined to joining walls 219a, 219b with first and second sealing members 415a, 415b sandwiched therebetween, preventing leakage of airflow 216 from the joining portions and allowing airflow 216 to pass through the interior as a duct.

[0061] 8 , the developing device 4 is separated from the photosensitive drum 1 by moving in the direction of arrow A (predetermined direction), which is substantially parallel to the opposing surface 218a and substantially perpendicular to the extending direction of the ribs 412 and 416. As described above, the side walls 414a and 414b are located downstream in the predetermined direction from the joining walls 219a and 219b, respectively. Therefore, at the separated position, the joining walls 219a and 219b of the duct wall 217 and the side walls 414a and 414b of the heat sink 409 are separated from each other, and do not interfere with each other when the developing device 4 is pulled out of the image forming apparatus main body 101.

[0062] Furthermore, in this embodiment, the distance between the tip 412a of the rib 416 that is located furthest downstream in the predetermined direction and the opposing surface 218a is greater than the distance between the tip of the joining wall 219a and the opposing surface 218a. In other words, the heat sink 409 is provided with a rib 416 in which the distance from the tip 412a of the rib to the opposing surface 218a is greater than the distance from the tip of the joining wall 419a to the opposing surface 218a of the top surface 218. By providing this rib 416, it is possible to position the rib 416 in a position where it interferes with the joining wall 219a when moving from the pressurized position to the separated position, thereby making it possible to increase the surface area of the heat sink 409.

[0063] As a result, in the developing device 4 equipped with the heat sink 409, it is possible to efficiently pass air between the ribs 412, 416 of the heat sink 409, thereby achieving both efficient cooling of the developer in the developing device and ease of maintenance. As a result, it is possible to form more stable images.

[0064] [Other embodiments] In this embodiment, the developing device has been described as having two developer carriers, but the present invention is also applicable to a developing device with one developer carrier. [Explanation of symbols]

[0065] 1. Photosensitive drum (image carrier) 4. Developing device 100 Image forming device 101 Image forming apparatus main body 215 Cooling duct 217 Duct wall (main body side wall) 218... Top surface (opposing wall) 218a...Opposite surface 219a...Joining wall (protruding wall, first wall on main body side) 219b... Joint wall (main body side second wall portion) 400···Developer container 404: First developing roller (developer carrier, first developer carrier) 405: Second developing roller (second developer carrier) 409 Heat sink (developing side wall) 410...Contact wall part 410a...Contact surface 410b...Heat dissipation surface 411...Heat radiation protrusion 412, 416 Rib (heat dissipation part) 414a... Side wall (developing side first wall portion) 414b... Side wall (developing side second wall portion) 415a... First seal member 415b... Second seal member

Claims

1. An image forming apparatus, an image carrier; a developing device including a developer container containing a developer containing toner and a carrier, and a developer carrier that carries the developer to develop an electrostatic latent image formed on the image carrier; a mounting portion for mounting the developing device on the image forming apparatus; a moving mechanism that moves the developing device mounted in the mounting portion from a separate position that is separate from the image carrier with respect to a development position where an electrostatic latent image formed on the image carrier is developed, to the development position; a cover member provided along a mounting direction of the developing device in the mounting portion, the cover member being attached to the developing container to cover the developing container; a wall member provided along the mounting direction, the wall member not moving together with the developing device when the developing device is moved from the separated position to the developing position by the moving mechanism; A first seal member; a second seal member disposed downstream of the first seal member in a movement direction in which the developing device is moved from the separated position to the developing position by the movement mechanism; a fan for generating an airflow for cooling the developing device, When the developing device is in the separated position, neither the first seal member nor the second seal member contacts the wall member, When the developing device is at the developing position, both the first seal member and the second seal member are in contact with the wall member, When the developing device is in the developing position, a space through which the airflow from the fan passes is formed along the mounting direction by the cover member, the wall member, the first seal member, and the second seal member. An image forming apparatus characterized by:

2. the cover member has a first rib and a second rib provided downstream of the first rib in the movement direction, When the developing device is in the developing position, the first seal member contacts the first rib, and the second seal member contacts the second rib.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. Both the first seal member and the second seal member are attached to the cover member.

3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

4. the cover member is attached to an upper portion of the developing container to cover the upper portion of the developing container, When the developing device is at the developing position, the wall member is located vertically above the cover member.

4. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

5. The thermal conductivity of the cover member is higher than the thermal conductivity of the developing container.

5. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

6. The thermal conductivity of the wall member is higher than the thermal conductivity of the developing container.

6. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

7. the thermal conductivity of the first seal member is higher than the thermal conductivity of the developing container; The thermal conductivity of the second seal member is higher than the thermal conductivity of the developing container.

7. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

8. The cover member is a heat sink.

8. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

9. The cover member is made of metal.

9. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

10. The wall member is made of metal.

10. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

11. The developing container is made of resin.

11. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

12. An image forming apparatus, an image carrier; a developing device including a developer container containing a developer containing toner and a carrier, and a developer carrier that carries the developer to develop an electrostatic latent image formed on the image carrier; a mounting portion for mounting the developing device on the image forming apparatus; a moving mechanism that moves the developing device mounted in the mounting portion from a separate position that is spaced apart from the image carrier with respect to a development position where an electrostatic latent image formed on the image carrier is developed, to the development position; a cover member provided along a mounting direction of the developing device in the mounting portion, attached to an upper portion of the developing container to cover the developing container; a wall member provided along the mounting direction, the wall member not moving together with the developing device when the developing device is moved from the separated position to the developing position by the moving mechanism; a seal member attached to the cover member; a fan for generating an airflow for cooling the developing device, When the developing device is in the developing position, the wall member is located vertically above the cover member, and a space through which the airflow from the fan passes is formed along the mounting direction by the cover member, the wall member, and the seal member. An image forming apparatus characterized by:

13. The thermal conductivity of the cover member is higher than the thermal conductivity of the developing container.

13. The image forming apparatus according to claim 12.

14. The thermal conductivity of the wall member is higher than the thermal conductivity of the developing container.

14. The image forming apparatus according to claim 12 or 13.

15. The thermal conductivity of the seal member is higher than the thermal conductivity of the developing container.

15. The image forming apparatus according to claim 12, wherein the image forming apparatus comprises: a first fixing member;

16. The cover member is a heat sink.

16. The image forming apparatus according to claim 12, wherein the image forming apparatus comprises: a first fixing member;

17. The cover member is made of metal.

17. The image forming apparatus according to claim 12, wherein the image forming apparatus comprises: a first fixing member;

18. The wall member is made of metal.

18. The image forming apparatus according to claim 12, wherein the image forming apparatus comprises: a first fixing member;

19. The developing container is made of resin.

19. The image forming apparatus according to claim 12, wherein the image forming apparatus comprises: a first fixing member; 20. An image forming apparatus, comprising: an image carrier; a developing device including a developer container containing a developer containing toner and a carrier, and a developer carrier that carries the developer to develop an electrostatic latent image formed on the image carrier; a mounting portion for mounting the developing device on the image forming apparatus; a moving mechanism that moves the developing device mounted in the mounting portion from a separate position that is spaced apart from the image carrier with respect to a development position where an electrostatic latent image formed on the image carrier is developed, to the development position; a cover member provided along a mounting direction of the developing device in the mounting portion, the cover member being attached to the developing container to cover the developing container; a wall member provided along the mounting direction, the wall member not moving together with the developing device when the developing device is moved from the separated position to the developing position by the moving mechanism; a seal member attached to the cover member; a fan for generating an airflow for cooling the developing device, the thermal conductivity of the seal member is higher than the thermal conductivity of the developing container; When the developing device is in the developing position, a space through which the airflow from the fan passes is formed along the mounting direction by the cover member, the wall member, and the seal member. An image forming apparatus characterized by:

21. The cover member is attached to an upper portion of the developing container to cover the upper portion of the developing container, When the developing device is at the developing position, the wall member is located vertically above the cover member.

21. The image forming apparatus according to claim 20.

22. The thermal conductivity of the cover member is higher than the thermal conductivity of the developing container.

22. The image forming apparatus according to claim 20, wherein the image forming apparatus is a recording medium.

23. The thermal conductivity of the wall member is higher than the thermal conductivity of the developing container.

23. The image forming apparatus according to claim 20, wherein the image forming apparatus comprises:

24. The cover member is a heat sink.

24. The image forming apparatus according to claim 20, wherein the image forming apparatus comprises:

25. The cover member is made of metal.

25. The image forming apparatus according to claim 20, wherein the image forming apparatus comprises:

26. The wall member is made of metal.

26. The image forming apparatus according to claim 20, wherein the image forming apparatus comprises:

27. The developing container is made of resin.

27. The image forming apparatus according to claim 20, wherein the image forming apparatus comprises: a first fixing member;

Images