JP2013225055A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: in order to suppress an increase in temperature of developer in a developing device, air blowing means for cooling a heat radiation member for developer, and air blowing means for cooling an air around the developing device are provided, which results in high costs.SOLUTION: An opening H is provided upstream an air channel of an air duct 50 that blows air to a heat radiation member 51 for developer, so as to exhaust an air before receiving heat from the heat radiation member 51 for developer from the opening H to a periphery of a developing device.

Description

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

  When the temperature of the developer contained in the developing device (developing device) that develops (visualizes) a latent image formed on an image carrier such as an electrophotographic photosensitive member in the image forming apparatus as described above increases, the developer The fluidity of the developer is lowered, and the developer coatability on the surface of the developing sleeve is lowered. As a result, the developability of the image carrier is lowered, and there is a possibility that an image defect occurs. The temperature rise of the developer is caused by two effects, that is, an influence due to self-heating generated by circulation of the developer and an influence due to heat received from the periphery of the developing device.

  Patent Document 1 discloses a technique for cooling a developer by applying air to a heat dissipating member in contact with the developer for the purpose of suppressing a temperature rise of the developer in the developing device. This technique mainly suppresses a temperature rise due to self-heating of the developer.

  Further, in order to cool the inside of the image forming apparatus main body including the developing device, an intake fan and an exhaust fan that take in air into the apparatus main body are generally provided. This is a technique that can suppress both a temperature increase due to self-heating of the developer and a temperature increase due to heat received from the periphery of the developing device.

JP 2007-279279 A

  In order to effectively suppress the temperature rise of the developer, it is desired to lower the temperature of the air applied to the heat radiating member and lower the temperature of the air flowing around the developing device.

  In order to realize this, a method of providing both an intake fan for applying wind to the heat radiating member and an intake fan for sending wind around the developing device is conceivable. However, in this case, the number of fans increases, resulting in an expensive configuration.

  In order to prevent contamination of the installation environment of the apparatus main body, it is necessary to suppress discharge of volatile organic compounds (VOC) and dust generated in the apparatus main body to the outside of the apparatus main body. In general, a method is used in which the air in the apparatus main body is purified and exhausted using a fan and a filter.

  Therefore, in order to effectively suppress the temperature rise of the developer, when an intake fan for sending air around the developing device is added, the air passing through the developing device is efficiently exhausted through the filter. It will be necessary to configure as described above. In addition, even if a fan is added, it is necessary to design the air pressure in the apparatus main body to be negative.

  An object of the present invention is to effectively suppress the temperature rise of the developer with a smaller number of fans.

  In order to achieve the above object, a typical configuration of an image forming apparatus according to the present invention includes a developer container containing a developer, and the developer is applied to an image carrier on which a latent image is formed. An image forming apparatus including a developing device that develops a latent image, the heat conducting member disposed in the developing container and absorbing heat from the developer in the developing container to dissipate heat to the air, and the heat conducting member A first air blower that is connected to one end of the air duct and blows air into the air duct, a second air blower that moves the ambient air of the developing device, An opening provided on the air duct upstream of the heat conducting member and on the air duct downstream of the first air blowing means, and from the first air blowing means into the air duct. A part of the blown air is sprayed around the developing device. And having a an opening for out.

  According to the present invention, the opening is provided in the air duct that sends air to the heat conducting member (developer radiating member), and the air is discharged from the opening to the periphery of the developing device. Air can be sent to the surroundings with a single fan (first blowing means). Therefore, the temperature rise of the developer can be effectively suppressed with a smaller number of fans.

(A) is a schematic block diagram of the image forming apparatus in Example 1, and (b) is a partially enlarged view. 1 is a transverse right side view (schematic diagram) of an image forming apparatus according to Embodiment 1. FIG. FIG. 4A is a transverse right side view (schematic diagram) of the image forming apparatus according to the second embodiment, and FIG.

  Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Example 1]
(1) Schematic Configuration of Image Forming Apparatus FIG. 1A is a schematic longitudinal front view of the image forming apparatus 100 in this embodiment, FIG. 1B is a partially enlarged schematic view, and FIG. 2 is a transverse left side view. is there.

  Here, in the image forming apparatus 100 according to the present exemplary embodiment, the front side (front side) is a side facing the user. The back side (back side) is the opposite side. The front direction is a direction from the back side to the front side, and the rear direction is a direction from the front side to the back side. Left and right are left or right when the image forming apparatus is viewed from the front side. The left direction is the direction from the right side to the left side, and the right direction is the direction from the left side to the right side. Up and down are up or down in the direction of gravity. The upward direction is the direction from the lower side to the upper side, and the lower direction is the direction from the upper side to the lower side.

  The image forming apparatus 100 is an inline type / intermediate transfer type four-color full-color electrophotographic color printer. The printer 100 forms a full-color image or a mono-color image corresponding to image data (electrical image information) input from an external host device 102 connected to a printer control unit (CPU) 101 on a sheet-like recording material P. Thus, an image formed product can be output.

  The control unit 101 is a control unit that comprehensively controls the operation of the printer 100 and exchanges various electrical information signals with the external host device 102 and a printer operation unit (not shown). It also controls electrical information signals input from various process devices and sensors, processing of command signals to various process devices, predetermined initial sequence control, and predetermined image forming sequence control. The external host device 102 is a personal computer, a network, an image reader, a facsimile, or the like.

  In the apparatus main body 100A of the printer 100, in FIG. 1A, four first to fourth image forming stations (image forming units) S (SY, SM, SC, SBk) are juxtaposed in a substantially horizontal direction. Each station S is different only in the toner color (toner type: spectral characteristics) of the developer contained in each developing device is different from yellow (Y), magenta (M), cyan (C), and black (Bk). The mechanism configuration is the same electrophotographic image forming mechanism. FIG. 1B is an enlarged schematic diagram of one station S of the four stations in FIG.

  That is, each station S has a drum-type electrophotographic photosensitive member (hereinafter referred to as a drum) D as an image carrier. Further, as a process means that acts on the drum D, there are a primary charging device 10, a laser scanner LS, a developing device 20, a primary transfer roller 30 as a primary transfer member, a cleaning device 40 including a cleaning blade, and the like. In the present embodiment, the primary charging device 10 is a corona charger, but may be another type of charger.

  In each station S, the drum D is disposed substantially horizontally in the apparatus main body 100A with one end side in the axial direction (rotational axis direction) being the front side and the other end side being the back side. The primary charging device 10, the developing device 20, the primary transfer roller 30, the cleaning device 40, and the like as process means acting on the drum D are arranged in parallel to the drum D, and the direction along the axial direction of the drum D (Front-back direction) is the longitudinal direction.

  The drum D of each station S is rotationally driven at a predetermined speed in the counterclockwise direction indicated by the arrow. Then, a Y color toner image corresponding to the Y color component image of the full color image to be formed is formed on the drum D of the first station SY. An M color toner image corresponding to the M color component image is formed on the drum D of the second station SM. A C-color toner image corresponding to the C-color component image is formed on the drum D of the third station SC. A Bk color toner image corresponding to the Bk color component image is formed on the drum D of the fourth station SBk.

  Since the electrophotographic image forming process and principle of the toner image for the drum D of each station S are known, the description thereof will be omitted.

  An intermediate transfer belt unit 31 is disposed below each station S. This unit 31 has an endless intermediate transfer belt ITB having flexibility as an intermediate transfer member. The belt ITB is suspended and stretched between three rollers including a driving roller 32, a tension roller 33, and a secondary transfer inner roller 34. The belt ITB is circulated and moved at a speed corresponding to the rotational speed of the drum D in the clockwise direction of the arrow by driving the driving roller 32.

  The secondary transfer outer roller 35 is in contact with the secondary transfer inner roller 34 with a predetermined pressing force via the belt ITB. A contact portion between the belt ITB and the secondary transfer outer roller 35 is a secondary transfer portion ST. The primary transfer roller 30 of each station S is disposed inside the belt ITB, and is in contact with the lower surface of the drum D via the belt ITB. In each station S, a contact portion between the drum D and the belt ITB is a primary transfer portion. A predetermined primary transfer bias is applied to the primary transfer roller 30 at a predetermined control timing.

  Y-color toner, M-color toner, C-color toner, and Bk-color toner respectively formed on the drum D of each station S are sequentially superposed and primary-transferred on the surface of the belt ITB that circulates and moves. As a result, an unfixed full-color toner image in which the four colors Y, M, C, and Bk are superimposed on the belt ITB is synthesized and conveyed to the secondary transfer unit ST.

  On the other hand, the recording material P stacked and accommodated in the paper feed cassette C disposed in the lower part of the apparatus main body 100A is separated and fed one sheet at a predetermined control timing. The recording material passes through the sheet path a, the registration roller pair 36, and the sheet path b, is introduced into the secondary transfer unit ST at a predetermined control timing, and is nipped and conveyed by the secondary transfer unit. A predetermined secondary transfer bias is applied to the secondary transfer outer roller 35. As a result, the full color toner image on the belt ITB side is secondarily transferred to the recording material P sequentially and collectively.

  Then, the recording material P that has exited the secondary transfer portion ST is separated from the surface of the belt ITB and introduced into the fixing device F. The recording material P is nipped and conveyed by the fixing roller pair of the fixing device F, and is heated and pressurized. As a result, the unfixed toner image is fixed on the recording material surface as a fixed image. The recording material P exiting the fixing device F passes through the sheet path c and is discharged as a full-color image formed product from the discharge port 37 to the discharge tray 38 outside the apparatus.

  In each station S, the toner remaining on the surface of the drum D after the primary transfer of the toner image to the belt ITB is removed from the drum surface by the cleaning device 40, and the drum D is repeatedly used for image formation. The toner remaining on the surface of the belt ITB after the secondary transfer of the toner image to the recording material P is removed from the belt surface by the belt cleaning device 39, and the belt ITB is repeatedly used for image formation.

  In the double-sided image forming mode, the recording material P on which the first-side image has been formed exiting the fixing device F is changed to the sheet path d side, switched back by the switchback path e, and enters the sheet path f. Then, the sheet is again introduced into the secondary transfer portion ST at a predetermined control timing through the sheet path a, the registration roller pair 36, and the sheet path b. As a result, image transfer is performed on the second surface of the recording material P that has been turned upside down. Thereafter, as in the case of image formation on the first surface, the recording material P passes through the fixing device F and the sheet path c and is discharged to the paper discharge tray 38 as a double-sided image formed product.

(2) Airflow In the following, the mechanism for cooling the developing device 20 in each station S will be described separately for the toner heat dissipation mechanism (heat sink, duct and fan) and the airflow around the developing device. I will explain the overall airflow.

(2-1) Toner Heat Dissipation Mechanism The developing device 20 has a long developing container 21 along the axial direction of the drum D. An opening 24 is formed along the length of the developing container 21 on the side facing the drum D. A developing roller (developing sleeve) 23 as a developing member is disposed in the opening 24 with the axial direction being the front-rear direction. The developing roller 23 faces the drum D, carries the developer in the developing container 21, and rotates at a predetermined speed in the clockwise direction of the arrow to apply the developer to the drum D. As a result, the latent image (electrostatic latent image) on the drum surface is developed as a toner image.

  In this embodiment, the developer is a two-component developer in which a magnetic carrier and a nonmagnetic toner are mixed. Inside the developing roller 23, a non-rotating magnet roller is disposed as a magnetic field generating member. The developer is held on the surface of the developing roller 23 by a magnetic force. A developer is accommodated in the developing container 21. Further, in the developing container 21, two upper and lower developer conveying screws 25 and 22 are arranged with the axial direction being the front-rear direction, respectively. The screws 25 and 22 circulate and agitate and convey the developer in the developing container 21 in the front-rear direction and supply the developer to the developing roller 23.

  A heat sink 51 as a heat-dissipating protrusion is provided along the length of the rear surface of the developing container 21 (the outer surface opposite to the developing roller 23 side). The heat sink 51 is made of a member having a thermal conductivity higher than that of the developing container 21 in a protruding shape (surface area is larger than that of a plane), and is in contact with the developer inside the developing container 21. Therefore, the toner of the developer can be efficiently cooled. That is, the heat sink 51 is a heat conducting member that is disposed along the longitudinal direction of the developing container 21 and absorbs heat from the developer in the developing container and dissipates heat to the air.

  In addition, the printer 100 according to the present exemplary embodiment includes an air duct 50 as an air path for cooling the toner so as to cover both the heat sink 51 provided in the longitudinal direction of the developing device 20 and the entire longitudinal direction of the developing device 20. . An air flow for cooling the heat sink 51 from the front side to the back side of the developing device 20 by sucking air from an intake fan (first blowing unit) F1 provided on the front side of the apparatus main body 100A in the blower duct. B is formed. That is, the intake fan F1 is connected to the air duct 50 at one end side (front side) and blows air into the air duct.

  The air duct 50 is provided with an opening (hole) H on the upstream side of the air path from the heat sink 51 and on the downstream side of the air path from the intake fan F1. In the present embodiment, the opening H is disposed upward on the upper surface side of the air duct 50. A part B1 of the air sucked by the intake fan F1 and taken into the air duct 50 is blown out (spouted) from the opening H to the outside of the air duct 50. That is, it blows out around the developing device 20. The remaining air passes through the air duct 50 and exchanges heat with the heat sink 51, and then is exhausted out of the apparatus main body 100A through the exhaust opening 82 on the back side of the apparatus main body 100A.

(2-2) Airflow around the developing device Next, the airflow inside the apparatus main body 100A and the airflow around the developing device will be described. An exhaust fan (second air blowing means) F2 for exhausting the air in the apparatus main body 100A is disposed at the lower part on the rear side of the apparatus. The function of the exhaust fan F2 is to suppress a temperature rise in the apparatus main body 100A due to excessive heat generation from the fixing device F. Further, the pressure in the apparatus main body 100A is kept at a negative pressure, and volatile organic compounds (VOC), scattered toner, dust, and the like generated in the apparatus main body 100A are collected by the filter 60. Further, the air around the developing device 20 is moved by driving the exhaust fan F2.

  An intake opening 71 is disposed at a position near the developing device 20 of the front cover 70 of the apparatus main body 100A. When the exhaust fan F2 is rotated, the inside of the apparatus main body 100A becomes negative pressure, and air is taken into the apparatus main body 100A from the intake opening 71. The taken-in air flows through the apparatus main body 100A and is exhausted from the exhaust fan F2 through the filter 60 and the exhaust opening 81.

  Around the developing device 20, as indicated by an arrow A, it flows from the front side to the back side in the longitudinal direction of the developing device 20. That is, it flows in the direction from the opening H of the air duct 50 toward the longitudinal center of the developing device 20.

(2-3) Airflow around the air duct 50 and the developing device The air sucked into the apparatus main body 100A from the air intake opening 71 is not only the heat received from the developing device 20, but also excessive heat from the fixing device F, It is heated by heat generated by friction between the drum D and the cleaning device 40, heat generated by the recording material P after passing through the fixing device F, and the like. In the present embodiment, cooler air B1 exiting the duct from the opening H of the blower duct 50 is mixed on the upstream side of the airflow around the developing device 20.

  Therefore, the air temperature around the developing device 20 is lower than when the opening H is not provided. As a result, heat radiation from the developing device 20 to the surroundings increases, so that an increase in toner temperature in the developing device 20 is suppressed.

  As described above, the opening H is provided in the air duct 50 that sends air to the heat radiating member 51. Since the air is sent from the opening H to the periphery of the developing device, the air can be sent to the heat radiating member 51 and the periphery of the developing device by one fan F1, so that the temperature of the developer can be increased with a smaller number of fans. Can be suppressed.

  In addition, by setting the position of the opening H of the air duct 50 on the upstream side of the air passage from the heat radiating member 51, cooler air before receiving heat from the heat radiating member 51 can be sent to the periphery of the developing device. The temperature rise of the developer can be effectively suppressed.

  In the above description, the air flow around the developing device 20 is configured to flow from the front side to the back side in the longitudinal direction of the developing device 20 (the flow indicated by the arrow A). They may not be parallel and may not be a straight flow.

  In this embodiment, the number of exhaust fans F2 is one in common with respect to the first to fourth image forming stations, but a plurality of exhaust fans F2 may be provided if necessary. In this embodiment, one fan F1 is provided for each of the first to fourth developing devices, but the duct is branched from one fan and blown to each developing device. You can also

[Example 2]
FIG. 3 is an explanatory diagram of the second embodiment. The second embodiment relates to the printer 100 of the first embodiment. In each station S, an opening H in which a toner bottle 90 for supplying toner to the two-component developer in the developing container 21 of the developing device 20 is provided in the air duct 50. Is disposed above the air flow B1 ejected from the air. Since the other apparatus configuration is the same as that of the printer of the first embodiment, the same reference numerals are given and the description thereof is omitted.

  The toner bottle 90 is a container for storing a replenishment developer for the developing container 21. The toner in the toner bottle 90 is conveyed from the front side to the back side in the apparatus main body 100A, and then supplied into the developing container 21 of the developing device 20 (the supply unit is not shown).

  When the toner temperature in the toner bottle 90 is high, the fluidity of the toner is lowered, and as a result, there is a risk of image failure. The rise in the temperature of the toner in the toner bottle 90 is more influenced by the heat received from the periphery of the toner bottle 90 than by the self-heating due to the toner conveyance.

  Therefore, by arranging the toner bottle 90 above the air flow B1 ejected from the opening H, the temperature rise around the toner bottle 90 can be suppressed, and as a result, the temperature rise of the toner in the toner bottle 90 can be suppressed. can do.

[Other matters]
1) Although the developing device 20 uses a two-component developer in the embodiment, it may be a device using a one-component developer (magnetic or non-magnetic toner). Either a contact development type apparatus or a non-contact development type apparatus may be used.

  2) Although the image forming apparatus according to the embodiment includes the first to fourth image forming stations as an inline system, the number of image forming stations is 2, 3 or 5 or more. It can also be configured. In addition, the monochromatic image forming apparatus may have an image forming apparatus configuration having one image forming station.

  3) The image forming process of the image forming apparatus is not limited to the electrophotographic image forming process. An electrostatic recording image forming process using an electrostatic recording dielectric as an image carrier, a magnetic recording image forming process using a magnetic recording magnetic material as an image carrier, and the like may be used.

  100..Image forming apparatus, D..Image carrier, 20..Developer, 21..Development container, 51..Heat conduction member (developer heat radiating member), 50..Blower duct, H..Opening F1 ··· First blower means, F2 ··· Second blower means,

Claims (3)

  An image forming apparatus comprising a developing container containing a developer, and having a developing device for developing the latent image by applying the developer to an image carrier on which a latent image is formed. A heat conduction member that absorbs heat from the developer in the developer container and dissipates heat to the air, a blower duct that covers the heat conduction member, and one end of the blower duct that is connected to the blower duct. A first blower that blows air; a second blower that moves the ambient air of the developing device; and an air duct upstream of the heat conducting member of the blower duct and the first blower An opening provided on the downstream side of the air passage from the first air blowing unit, the opening blowing a part of the air blown into the blower duct from the first blowing unit to the periphery of the developing device. An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein the direction of the air flow by the second air blowing unit is a direction from the opening toward a longitudinal center of the developing device.   3. The image forming apparatus according to claim 1, wherein a container for storing a replenishment developer for the developing container is disposed above the air flow ejected from the opening.