JP2018031943A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of emission of ultrafine particle dust emitted from fixing means to the outside compared with a case where an image forming apparatus comprises an air intake duct that is connected on the upstream side of filter means on the inside of exhaust duct and introduces air from the outside of a housing.SOLUTION: An image forming apparatus comprises: fixing means that heats a recording medium holding an unfixed image to fix the image; first exhaust means 76 that is arranged at one end of the fixing means along a direction intersecting with the recording medium conveying direction and exhausts air around the fixing means to the outside; second exhaust means 87 that is arranged on the downstream side of the fixing means along the recording medium conveyance direction and exhausts ambient air to the outside; and an exhaust duct member 77 that combines exhausted gas from the first exhaust means 76 and exhausted gas from the second exhaust means 87 and guides the combined gas to an exhaust port 78 in the back face of an apparatus body.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image forming apparatus.

  Conventionally, in an image forming apparatus, as a technique for reducing the discharge amount of ultra fine particles (UFP) and volatile organic compounds (VOC) discharged from a fixing device, for example, Patent Document 1 And those disclosed in Patent Document 2 and the like have already been proposed. The ultrafine particle dust is dust having a diameter of 0.1 μm or less.

  Patent Document 1 discloses a case, an image forming unit that forms an unfixed image on an image support material, and the image support material that passes through the image support material and heats the unfixed image formed on the image support material. A fixing device for fixing the image supporting material; an exhaust duct for exhausting air in the vicinity of the fixing device to the outside of the housing; and suctioning air in the vicinity of the fixing device; A suction member that circulates inside and a first filter means that is provided inside the exhaust duct and carries a polar adsorbent that adsorbs a polar substance.

  Further, Patent Document 1 has an aspect in which an intake duct is further connected to the upstream side of the first filter means inside the exhaust duct and introduces air from the outside of the casing. .

  Patent Document 2 includes a cylindrical or annular fixing member and a heating source that heats the fixing member to a temperature for fixing, and presses the conveyed sheet against the outer peripheral surface of the fixing member to form the sheet. An image forming apparatus for fixing an image, the exhaust duct having an intake port provided at a position facing the fixing member with respect to a width direction perpendicular to a circumferential direction of the fixing member, and the exhaust duct And a filter member capable of capturing fine particles generated from the fixing member flowing through the exhaust duct, and facing at least a part of the sheet on the downstream side of the fixing member in the sheet conveyance direction. A cooling duct having a blow-out opening provided at a position where the discharge duct is provided, a location different from the intake port in the exhaust duct, and a difference from the blow-out port in the cooling duct A common path having one end that communicates with a location, and a second end that communicates with the outside of the casing of the image forming apparatus or a location separated from the fixing member in the casing, and a fan inserted in the common path An exhaust flow in which air flows from the one end to the other end through the common path according to an initial burst condition in which the fine particles are discharged from the fixing member, and the one end from the other end through the common path. And a control unit that operates the fan so as to switch and generate a guided airflow through which air flows.

JP 2010-276904 A JP 2011-180341 A

  The object of the present invention is to be connected to the upstream side of the filter means inside the exhaust duct and to be discharged from the fixing means to the outside as compared with a case where an intake duct for introducing air from the outside of the housing is provided. The purpose is to reduce the discharge amount of ultra fine particles.

The invention described in claim 1 is a fixing unit that heats and fixes a recording medium holding an unfixed image;
A first exhaust unit disposed at one end of the fixing unit along a direction intersecting the conveyance direction of the recording medium, and discharging the air around the fixing unit to the outside;
A second exhaust unit disposed on the downstream side of the fixing unit in the conveyance direction of the recording medium and exhausting ambient air to the outside;
An exhaust duct member that joins the exhaust of the first exhaust means and the exhaust of the second exhaust means and guides it to the exhaust port on the back of the apparatus body;
An image forming apparatus.

According to a second aspect of the present invention, the exhaust duct member is
A first exhaust duct member for guiding the exhaust of the first exhaust means to the back surface of the apparatus body;
A second exhaust duct member for guiding the exhaust of the second exhaust means to the back surface of the apparatus body;
With
The exhaust of the first exhaust means and the exhaust of the second exhaust means are merged with the first exhaust duct member disposed below the second exhaust duct member immediately before the exhaust port. An image forming apparatus according to claim 1.

  A third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein a filter member for removing a specific component in the exhaust gas is provided at a position immediately before the exhaust port of the exhaust duct member.

  A fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, wherein the exhaust duct member has an auxiliary exhaust opening that is opened on an upper surface of the apparatus main body.

  According to the first aspect of the present invention, the fixing means is connected to the upstream side of the filter means inside the exhaust duct and is provided with an inlet duct for introducing air from the outside of the housing. It is possible to reduce the amount of ultrafine particle dust discharged from the outside.

  According to the invention described in claim 2, the first exhaust duct member and the second exhaust duct member are arranged such that the first exhaust duct member is positioned below the second exhaust duct member at the outlet. Compared to the case where the merging is not performed, the exhaust of the first exhaust means and the exhaust of the second exhaust means can be mixed more efficiently.

  According to the third aspect of the present invention, the discharge amount of the specific component can be reduced as compared with the case where the outlet portion of the exhaust duct member is not provided with the filter member for removing the specific component in the exhaust gas. .

  According to the fourth aspect of the present invention, the rear surface of the apparatus main body is a shielding object such as a wall as compared with the case where the exhaust duct member does not have the auxiliary exhaust opening opened on the upper surface of the apparatus main body. Even when it is disposed close to the exhaust duct member, the exhaust duct member can be surely exhausted to the outside.

1 is a schematic configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. 1 is a configuration diagram illustrating an image forming unit of an image forming apparatus according to Embodiment 1 of the present invention; FIG. 3 is a cross-sectional configuration diagram illustrating a fixing device. 1 is a perspective configuration diagram showing a main part of an image forming apparatus according to Embodiment 1 of the present invention. 1 is a perspective configuration diagram showing a main part of an image forming apparatus according to Embodiment 1 of the present invention. 1 is a perspective configuration diagram showing a main part of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a perspective configuration diagram illustrating a back side of the image forming apparatus main body. 2 is a perspective configuration diagram illustrating a state in which a cover on the back side of the image forming apparatus main body is removed. FIG. It is a perspective lineblock diagram showing a filter member. It is a perspective block diagram which shows the effect | action of the image forming apparatus which concerns on Embodiment 1 of this invention. It is a graph which shows an experimental result.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
1 and 2 show an image forming apparatus according to the first embodiment. FIG. 1 shows an outline of the entire image forming apparatus, and FIG. 2 shows an enlarged main part (image forming apparatus, etc.) in the image forming apparatus.

<Overall Configuration of Image Forming Apparatus>
The image forming apparatus 1 according to Embodiment 1 is configured as a monochrome image forming apparatus adopting, for example, an electrophotographic system. The image forming apparatus 1 includes an automatic document conveying device 2 that automatically conveys a document (not shown) to the reading position on the upper portion of the apparatus main body 1a, and an image reading device that reads an image of a document (not shown) on the document placement glass 4. 3 is provided.

  The image reading device 3 is conveyed by the automatic document conveying device 2 so as to pass the reading position of the document placing glass 4, or an image of a document (not shown) placed on the document placing glass 4 is sent by the light source 6. While illuminating, a reflected light image from a document (not shown) is imaged on the image reading element 9 by the imaging lens 8 via the full-rate mirror 7a and the half-rate mirror 7b, thereby reading an image of the document (not shown). It is configured.

  The image forming apparatus 1 includes an image forming device 10 as an example of an image forming unit that forms a toner image developed with toner constituting a developer, and a toner image formed by the image forming device 10 as an example of a recording medium. A transfer device 20 for transferring to the recording paper 5, a paper feeding device 30 for accommodating and transporting the required recording paper 5 to be supplied to the transfer position of the transfer device 20, and the recording paper 5 transferred by the transfer device 20 And a fixing device 40 for fixing the toner image.

  As shown in FIG. 1, the image forming apparatus 10 includes a rotating photosensitive drum 11 as an example of an image holding member. Around the photosensitive drum 11, toner image forming means such as the following is provided. Each apparatus as an example is mainly arranged. The main devices are a charging device 12 that charges a peripheral surface (image holding surface) on the photosensitive drum 11 on which an image can be formed to a required potential, and image information (on the charged peripheral surface of the photosensitive drum 11). The exposure device 13 as an example of an electrostatic latent image forming unit that irradiates light based on a signal) to form an electrostatic latent image having a potential difference, and develops the electrostatic latent image with toner of a developer to form a toner image. The developing device 14 as an example of the developing means, the transfer device 20 as an example of the transfer means for transferring the toner image to the recording paper 5, and a necessary charge are given before cleaning the peripheral surface of the photosensitive drum 11. And a pre-cleaning charging device 15 (see FIG. 2) for discharging and a drum for cleaning by removing adhering matter such as toner remaining on the image holding surface of the photosensitive drum 11 discharged by the pre-cleaning charging device 15 A cleaning device 16 or the like.

  The photosensitive drum 11 is formed by forming an image holding surface having a photoconductive layer (photosensitive layer) made of a photosensitive material on the peripheral surface of a cylindrical or columnar base material to be grounded. The photosensitive drum 11 is supported so as to rotate in a direction indicated by an arrow A when power is transmitted from a driving device (not shown).

  The charging device 12 is configured by a non-contact type charging device such as a scorotron disposed in a non-contact state on the surface of the photosensitive drum 11. A charging voltage is supplied to the charging device 12. As the charging voltage, when the developing device 14 performs reversal development, a voltage or current having the same polarity as the charging polarity of the toner supplied from the developing device 14 is supplied. In addition, as the charging device 12, a contact-type charging device including a contact-type charging roll arranged in contact with the photosensitive drum 11 may be used.

  The exposure device 13 is a photosensitive drum that has been charged with light LB configured according to image information of a document (not shown) read by the image reading device 3 or image information input to the image forming device 1. 11 is applied to the peripheral surface to form an electrostatic latent image. When the latent image is formed, the exposure device 13 is read by the image reading device 3 or inputted to the image forming device 1 by any means, and information (signal) of the image processed by the image processing unit is transmitted. .

  The developing device 14 includes a developing roll that holds the developer and conveys it to a developing area facing the photosensitive drum 11 in a housing in which an opening and a developer storage chamber are formed, and stirring the developer. A stirring and conveying member such as two screw augers that convey the developing roll to pass therethrough and a layer thickness regulating member that regulates the amount (layer thickness) of the developer held by the developing roll are arranged. . A developing bias voltage is supplied to the developing device 14 between a developing roll and the photosensitive drum 11 from a power supply device (not shown). As the developer, a two-component developer containing a nonmagnetic toner and a magnetic carrier is used.

  As shown in FIG. 2, the transfer device 20 is a contact-type transfer device that includes a transfer roll 22 that contacts and rotates around the photosensitive drum 11 via a transfer belt 21 and is supplied with a transfer voltage. is there. As the transfer voltage, a DC voltage having a polarity opposite to the charging polarity of the toner is supplied from a power supply device (not shown). The transfer device 20 includes a transfer belt 21 that rotates while passing through a transfer position between the photosensitive drum 11 and the transfer roll 22, and a plurality of transfer belts 21 that are rotatably supported by holding the transfer belt 21 in a desired state from the inner surface thereof. Belt support rolls 23 and 24, a transfer roll 22 as an example of a transfer unit disposed on the inner peripheral surface (back surface) side of the transfer belt 21 and transferring the toner image on the photosensitive drum 11 to the recording paper 5, The belt cleaning device 25 mainly removes adhering matters such as toner and paper dust remaining on the outer peripheral surface of the transfer belt 21 after passing through the transfer roll 22 and cleaning it.

  As the transfer belt 21, an endless belt made of a material in which a resistance adjusting agent such as carbon black is dispersed in a synthetic resin such as polyimide resin or polyamide resin is used. The belt support roll 23 is configured as a drive roll that is rotationally driven by a driving device (not shown), and the belt support roll 24 is configured as a tension applying roll that applies tension to the transfer belt 21.

  The pre-cleaning charging device 15 is configured by a non-contact charging device such as a corotron disposed in a non-contact state on the surface of the photosensitive drum 11 that has passed the transfer process. A charging voltage is supplied to the pre-cleaning charging device 15. As the charging voltage, for example, a voltage or current having a polarity opposite to the charging polarity of the toner is supplied.

  The drum cleaning device 16 is disposed so as to come into contact with the container-shaped main body, which is partially opened, and the peripheral surface of the photosensitive drum 11 after transfer with a required pressure, and removes adhered matters such as residual toner to be cleaned. A cleaning brush, a cleaning plate disposed so as to come into contact with the peripheral surface of the photosensitive drum 11 after transfer at a required pressure, and cleaning by removing deposits such as residual toner, and toner removed by the cleaning brush and the cleaning plate It is composed of a delivery member such as a screw auger that collects and adheres to the collection system (not shown).

  As shown in FIG. 1, the fixing device 40 rotates in a direction indicated by an arrow inside a housing 41 in which an inlet and an outlet for the recording paper 5 are formed, and the surface temperature is maintained at a predetermined temperature. A roll-form or belt-form heating rotator 42 heated by the heating means, and a roll-form or belt-form rotating in contact with a predetermined pressure in a state substantially along the axial direction of the heating rotator 42 The pressurizing rotating body 43 and the like are arranged. In the fixing device 40, a contact portion where the heating rotator 42 and the pressing rotator 43 are in contact becomes a fixing processing portion (nip portion) N that performs a required fixing process (heating and pressing). The configuration of the fixing device 40 will be described in detail later.

  The paper feeding device 30 is arranged so as to exist at a lower position along the vertical direction of the transfer device 20. The paper feeding device 30 includes a plurality (or a single number) of paper storage bodies 31 for storing recording papers 5 of a desired size and type, and sending out the recording paper 5 from the paper storage bodies 31 one by one. It is mainly composed of the device 32. The paper container 31 is attached, for example, so that it can be pulled out to the front side (side surface on which the user faces during operation) of the image forming apparatus 1 by a guide rail (not shown).

  Examples of the recording paper 5 include thin paper such as plain paper and tracing paper used for electrophotographic copying machines and printers, or an OHP sheet. In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper 5 is preferably as smooth as possible. For example, coated paper in which the surface of plain paper is coated with resin, art paper for printing, etc. So-called cardboard having a relatively large basis weight can be suitably used.

  As shown in FIG. 1, a plurality or a single pair of sheet conveying rolls 33 to convey the recording sheet 5 sent out from the sheet feeding device 30 to the secondary transfer position between the sheet feeding device 30 and the transfer device 20. A paper feed conveyance path 37 including a conveyance guide 36 and a conveyance guide (not shown) is provided. The pair of sheet conveyance rolls 36 disposed at the position immediately before the secondary transfer position in the sheet feeding conveyance path 37 is configured as a roll (registration roll) that adjusts the conveyance timing of the recording sheet 5, for example. Further, in the portion of the apparatus main body 1a close to the discharge port of the recording paper 5, the recording paper 5 after fixing sent out by the fixing device 40 is discharged to a paper discharge section (not shown) provided on the side surface of the image forming apparatus 1. The sheet discharge roll pair 38 is provided.

  Further, below the pair of paper discharge rolls 38, both sides of the recording paper 5 on which the image is formed on one side are reversed and conveyed to the transfer device 20 again to form an image on the back surface of the recording paper 5. A transport path 39 is provided.

  In FIG. 1, reference numeral 145 denotes a toner cartridge that is disposed along a direction perpendicular to the paper surface and that contains a developer containing at least toner to be supplied to the developing device 14.

<Operation of Image Forming Apparatus>
Hereinafter, a basic image forming operation by the image forming apparatus 1 will be described.

  When the image forming apparatus 1 receives command information for a monochrome image forming operation (printing) request from a user interface (not shown), a printer driver, or the like, the image forming device 10, the transfer device 20, the fixing device 40, and the like are started.

  In the image forming apparatus 10, as shown in FIG. 1, first, the photosensitive drum 11 rotates in the direction indicated by the arrow A, and the charging device 12 causes the surface of the photosensitive drum 11 to have a predetermined polarity (the embodiment). 1 is negative polarity) and charged to a potential. Subsequently, the exposure device 13 emits light on the surface of the charged photosensitive drum 11 based on a document image (not shown) read by the image reading device 3 or an image signal input to the image forming device 1. Is irradiated with light LB to form an electrostatic latent image having a required potential difference on the surface thereof.

  Subsequently, the image forming device 10 supplies toner charged to a required polarity (minus polarity) from the developing roll to the electrostatic latent image formed on the photosensitive drum 11 and electrostatically attaches the toner. Develop. By this development, the electrostatic latent image formed on the photosensitive drum 11 is visualized as a monochrome toner image developed with black toner.

  Subsequently, when the toner image formed on the photosensitive drum 11 of the image forming apparatus 10 is conveyed to the transfer position, the transfer roll 22 of the transfer apparatus 20 conveys the toner image by the transfer belt 21 of the transfer apparatus 20. The recording paper 5 is transferred.

  Further, in the image forming apparatus 10 that has completed the transfer, after the pre-cleaning charging device 15 neutralizes the surface of the photosensitive drum 11, the drum cleaning device 16 removes the adhering matter so as to scrape off the surface, and the surface of the photosensitive drum 11. Clean. As a result, the image forming apparatus 10 is brought into a state in which the next image forming operation can be performed.

  On the other hand, in the paper feeding device 30, the required recording paper 5 is sent out to the paper feeding conveyance path 37 in accordance with the image forming operation. In the paper feed conveyance path 37, a pair of paper conveyance rolls 36 as registration rolls sends the recording paper 5 to the transfer belt 21 of the transfer device 20 in accordance with the transfer timing.

  At the transfer position, the transfer roll 22 of the transfer device 20 transfers the toner image on the photosensitive drum 11 onto the recording paper 5 conveyed by the transfer belt 21.

  Subsequently, the recording paper 5 onto which the toner image has been transferred is conveyed to the fixing device 40 by the transfer belt 21. In the fixing device 40, a necessary fixing process (heating and pressing) is performed by introducing the recording paper 5 after transfer through the nip portion N between the rotating heating rotating body 42 and the pressing rotating body 43. ) To fix the unfixed toner image on the recording paper 5. Finally, the recording paper 5 after the fixing is finished is discharged by a paper discharge roll pair 38 on the side surface of the image forming apparatus 1 in an image forming operation only for forming an image on one side. It is discharged to a part (not shown).

  Further, when images are formed on both sides of the recording paper 5, the recording paper 5 with the image formed on one side is not discharged to a paper discharge unit (not shown), and the recording paper 5 is turned upside down. The toner image is transferred again to the transfer device 20 via the transfer path 39 for both sides, and the toner image is transferred to the back surface of the recording paper 5. The recording paper 5 on which the toner image is transferred on the back side is conveyed to the fixing device 40 by the transfer belt 21, subjected to fixing processing (heating and pressurization) by the fixing device 40, and an image forming apparatus by the paper discharge roll pair 38. The paper is discharged to a paper discharge unit (not shown) installed on the side surface of 1.

  Through the above operation, the recording paper 5 on which the monochrome image is formed is output.

<Configuration of fixing device>
FIG. 3 is a cross-sectional configuration diagram of a fixing device used in the image forming apparatus according to the first embodiment.

  As shown in FIG. 3, the fixing device 40 includes a housing 41 formed of a box having a substantially rectangular parallelepiped shape in which an introduction port 41 a and a discharge port 41 b of the recording paper 5 are formed. The recording paper 5 transported by the transfer belt 21 and peeled off from the transfer belt 21 is introduced into the introduction port 41a of the casing 41 as a pair of rotating bodies that are pressed against each other to form the nip portion N. A flat plate-shaped inlet guide member 44 is provided that leads to a nip portion N where a heating roll 42 as an example and a pressing roll 43 as an example of a pressure rotating body are in pressure contact with each other. In addition, a pair of upper and lower opposingly disposed recording papers 5 that have been subjected to fixing processing by the nip portion N where the heating roll 42 and the pressure roll 43 are pressed against each other are disposed at the discharge port 41 b of the housing 41. Outlet guide members 45 and 46 are provided.

  A heating roll 42 and a pressure roll 43 are provided inside the casing 41 of the fixing device 40. The heating roll 42 and the pressure roll 43 are arranged so as to be switchable between a pressure contact state in which they are pressed against each other at a predetermined pressure and a separated state in which they are separated from each other. The heating roll 42 is a heat-resistant elastic body made of a metal core 47 formed in a cylindrical shape with a metal such as stainless steel or an aluminum alloy, and a heat-resistant silicone rubber coated on the surface of the metal core 47 relatively thickly. A layer 48 and a release layer 49 made of tetrafluoroethylene, PFA or the like coated on the surface of the heat resistant elastic layer 48 are provided. Further, inside the heating roll 42, three halogen lamps 50 are arranged as heating sources. The heating roll 42 is heated by the halogen lamp 50 from the inside, and the surface temperature of the heating roll 42 is detected by the temperature sensor 51 so that the surface temperature of the heating roll 42 becomes a predetermined fixing processing temperature. Energization is controlled by control means (not shown).

  A cleaning web 52 made of a nonwoven fabric or the like for removing foreign matters such as toner adhering to the surface of the heating roll 42 is pressed against the surface of the heating roll 42 by the cleaning roll 53. The cleaning web 52 is supplied from the web supply roll 54 and is taken up at a predetermined timing by the web take-up roll 55.

  On the other hand, the pressure roll 43 includes a cored bar 56 formed in a cylindrical shape having a central axis with a metal such as stainless steel or an aluminum alloy, and a heat resistant coating in which the surface of the cored bar 56 is thinly coated as compared with the heating roll 42. The heat-resistant elastic body layer 57 made of silicone rubber or the like having a property and the release layer 58 made of tetrafluoroethylene, PFA, or the like coated on the surface of the heat-resistant elastic body layer 57 are configured.

  As shown in FIG. 3, the fixing device 40 has a recording paper 5 on which an unfixed toner image is fixed by passing through a nip portion N where the heating roll 42 and the pressure roll 43 are pressed. A pair of discharge rolls 59 for discharging from 40 is provided.

<Configuration of Characteristic Part of Image Forming Apparatus>
In the image forming apparatus 1 according to the first embodiment, as shown in FIG. 4, the air around the fixing device 40 is placed on the upper portion of the fixing device 40 from the front (front) side to the back (rear). ) Side and is provided with a wind guide passage 70 for discharging from the back of the apparatus main body 1a to the outside. The air guide passage 70 is a heat insulating wall formed in a relatively thick and hollow space that partitions the fixing device 40 and the image forming device 10 on the upstream side of the fixing device 40 along the conveyance direction of the recording paper 5. The partition wall 71 faces the upper part of the fixing device 40 with a casing 41 of the fixing device 40 through a required gap, and is downstream from the upper end of the partition wall 71 along the conveyance direction of the recording paper 5 of the fixing device 40. And a hanging wall 73 provided downward from the end of the ceiling wall 72 in the vertical direction on the downstream side in the conveyance direction of the recording paper 5 of the fixing device 40. Yes.

  On the ceiling wall 72 of the air guide passage 70, a first area that guides air around the fixing device 40 to the back side of the apparatus main body 1 a in a downstream area along the conveyance direction of the recording paper 5 of the fixing device 40. An exhaust duct member 74 is integrally provided. The first exhaust duct member 74 is formed in a rectangular tube shape having a rectangular cross section in which the lower end surface 74 a is fully opened toward the fixing device 40. The rear side end of the air guide passage 70 is closed by the back wall 75 except for the region of the first exhaust duct member 74.

  As shown in FIG. 4, the first exhaust duct member 74 includes an extended portion 74 b whose cross-sectional area is increased upward at an end portion on the back surface side. As shown in FIGS. 5 and 6, on the back side of the first exhaust duct member 74, a first exhaust fan 76 as an example of a first exhaust unit that exhausts air around the fixing device 40 to the outside. Is arranged. For example, a sirocco fan is used as the first exhaust fan 76. The first exhaust duct member 74 and the first exhaust fan 76 are connected via a connection duct 77. The connecting duct 77 is formed as a substantially rectangular parallelepiped box. An extended portion 74 b of the first exhaust duct member 74 is connected to the end face on the front side of the connection duct 77. A first exhaust fan 76 is attached to an end face on the back side of the connection duct 77 with an air inlet (not shown) being opened.

  As shown in FIG. 6, a merging duct 80 is connected to the exhaust port 78 of the first exhaust fan 76. The merging duct 80 is a member for merging the exhaust of the first exhaust fan 76 and the exhaust of a second exhaust fan, which will be described later, and discharging it from the back surface of the apparatus main body 1a to the outside. The joining duct 80 is configured as a vertically long, substantially rectangular parallelepiped box body in which the rear end surface located on the back side of the apparatus main body 1a is fully opened and a part of the upper end surface continuous to the rear end surface is opened. ing. The inside of the merging duct 80 is partitioned up and down by a flat partition member 81 extending from an end on the front side of the apparatus main body 1a to an intermediate position on the back side. Of the inside of the joining duct 80 partitioned by the partition member 81, a space positioned below constitutes a first inflow portion 82 into which exhaust from the first exhaust fan 76 flows. On the other hand, the space located above constitutes a second inflow portion 83 into which the exhaust from the second exhaust fan flows. In addition, the space on the back side in the merging duct 80 that is not partitioned by the partition member 81 and communicates vertically constitutes a merging portion 84 where the exhaust from the first exhaust fan 76 and the exhaust from the second exhaust fan merge. doing.

  A first connection portion 85 to which the exhaust port 78 of the first exhaust fan 76 is connected is provided on one side surface (the right side surface in FIG. 6) of the merging duct 80 so as to protrude into a rectangular tube shape. . The lower end surface of the first connection portion 85 is located below the bottom portion of the first inflow portion 82. The bottom surface of the merging duct 80 forms an inclined surface through which the exhaust of the first exhaust fan 76 is introduced into the merging duct 80 obliquely upward from the first connecting portion 85. Further, the inner side surface 86 of the merging duct 80 facing the first connection portion 85 is a curved surface that is curved so as to change the direction of the exhaust discharged from the first exhaust fan 76 to the back side of the apparatus main body 1a. It has become.

  Further, on the downstream side of the fixing device 40 in the conveyance direction of the recording paper 5, as shown in FIG. 4, a second exhaust fan as an example of a second exhaust unit that exhausts ambient air to the outside. 87 is provided. As the second exhaust fan 87, for example, a sirocco fan is used similarly to the first exhaust fan. A downstream space 88 along the conveyance direction of the recording sheet 5 of the fixing device 40 includes an upstream side wall 89 formed by extending the hanging wall 73 of the air guide passage 70 upward in the vertical direction, and the upstream side wall 89. A second ceiling wall 90 disposed at a position higher than the first ceiling wall 72 toward the downstream side in the conveyance direction of the recording paper 5 at the upper end of the recording paper 5, and on the downstream side of the second ceiling wall 90 It is surrounded by a downstream side wall 91 that hangs downward from the end portion in the vertical direction.

  As described above, the second exhaust fan 87 is attached to the upper part of the second ceiling wall 90 at the center along the direction intersecting the conveyance direction of the recording paper 5. The second ceiling wall 90 has an air inlet (not shown) through which air in the downstream space 88 along the conveyance direction of the recording paper 5 of the fixing device 40 is sucked by the second exhaust fan 87 and discharged to the outside. It is open. The exhaust port 92 of the second exhaust fan 87 is connected to a second exhaust duct member 93 that guides the exhaust of the second exhaust fan 87 to the back surface of the apparatus main body 1a. The second exhaust duct member 93 is attached to the upper surface of the second ceiling wall 90 toward the back side of the apparatus main body 1a. The second exhaust duct member 93 is formed in an elongated and substantially rectangular tube shape. Further, the end portion on the back surface side of the second exhaust duct member 93 constitutes an extended portion 93a having an opening area increased upward. As shown in FIG. 6, the extended portion 93 a of the second exhaust duct member 93 is directly connected to the second inflow portion 83 partitioned by the partition member 81 of the merging duct 80.

  As shown in FIG. 6, the exhaust of the first exhaust fan 76 and the exhaust of the second exhaust fan 87 merged by the merge duct 80 are provided at the rear side end of the merge duct 80. An exhaust port 94 for discharging from the back surface of 1a is opened over the entire surface. The exhaust port 94 of the merging duct 80 is provided with a sealing member 95 formed in an elongated prismatic shape from a synthetic resin foam (sponge) or the like on both side surfaces and lower end surfaces thereof by means such as adhesion via a double-sided tape. It has been. As shown in FIG. 7, the exhaust port 94 of the merging duct 80 is disposed on the back surface of the apparatus main body 1a and is covered with back cover 96a, 96b divided into a plurality of the apparatus main body 1a. The back covers 96a and 96b of the apparatus main body 1a are provided with a plurality of louvers 97a and 97b as an example of a plurality of foreign matter intrusion suppression plates that partially cover the exhaust port 94 of the merging duct 80 and suppress the entry of foreign matters. It has been.

  Also, an auxiliary exhaust opening 98 formed so as to be continuous with the exhaust port 94 is opened at the upper end surface of the merging duct 80. As shown in FIG. 7, the auxiliary exhaust opening 98 of the merging duct 80 is covered by an upper cover 98a disposed on the upper end surface of the apparatus main body 1a. The upper cover 98a of the apparatus main body 1a is provided with a number of minute exhaust holes 99 for discharging air from the auxiliary exhaust opening 98 of the merging duct 80 to the outside.

  As shown in FIGS. 6 and 8, the merging duct 80 removes specific components in the exhaust gas at a position immediately before the merging portion 84 where the first inflow portion 82 and the second inflow portion 83 merge. A filter member 100 is provided. FIG. 8 shows a state in which the back covers 96a and 96b and the upper cover 98a are removed from the apparatus main body 1a. As shown in FIG. 6, an opening 101 for attaching / detaching the filter member 100 is opened on the upper end surface of the merging duct 80. As shown in FIG. 9, the filter member 100 includes a synthetic resin frame 100 a formed in a rectangular shape corresponding to the cross-sectional shape of the merging duct 80, and a filter stretched over the opening of the frame 100 a. 100b. The filter 100b is formed in a thin film shape or a sheet shape. The filter 100b is made of a single layer or a plurality of layers of non-woven fabric, and the base fabric itself for removing dust or ultra fine particle dust (UFP) in the exhaust, or ultra fine dust (UFP) or volatile in the base fabric. A chemical agent for removing a specific component such as an organic compound (VOC) is applied by means such as impregnation or coating as necessary. A grip portion 100 d for attaching and detaching the filter member 100 is provided at the upper end portion of the filter member 100.

  As shown in FIG. 7, the filter member 100 is used for merging in a state where a lid (not shown) that closes the opening 102 for operation provided at a position corresponding to the filter member 100 of the merging duct 80 is removed. The grip part 100d of the filter member 100 is attached and detached from the opening part 101 of the duct 80 by hand.

<Operation of Characteristic Part of Image Forming Apparatus>
In the image forming apparatus 1 according to this embodiment, as shown in FIG. 10, the first and second exhaust fans 76 and 87 are driven in synchronization with the image forming operation. The first exhaust fan 76 is arranged around the fixing device 40, that is, upstream of the fixing device 40 along the conveyance direction of the recording paper 5 via the air guide passage 70 and the first exhaust duct member 74. The heated air discharged from the upper part of the image forming apparatus and the downstream side of the fixing device 40 in the recording sheet conveyance direction is sucked. The air sucked by the first exhaust fan 76 is sent to the inside of the merging duct 80 through the connecting duct 77.

  On the other hand, the second exhaust fan 87 sucks mainly air discharged from the recording paper 5 that has passed through the fixing device 40 in a downstream space 88 along the conveyance direction of the recording paper 5 of the fixing device 40. The air sucked by the second exhaust fan 87 is sent to the inside of the merging duct 80 via the second exhaust duct member 93 as shown in FIG.

  As shown in FIGS. 6 and 8, the exhaust gas sent into the merging duct 80 has dust, ultrafine particle dust (UFP), or volatile organic compound (UFP) in the exhaust gas by the filter 100 b of the filter member 100. Components such as VOC) are removed or reduced. Further, the exhaust gas from which components such as dust, ultrafine particle dust (UFP), or volatile organic compound (VOC) have been removed or reduced by the filter member 100 is merged at the merging portion 84 in the merging duct 80. At that time, in the merging duct 80, the exhaust from the first exhaust duct member 74 is located below, and the exhaust from the second exhaust duct member 93 is joined above. For this reason, the gas such as water vapor evaporating from the heated recording paper 5 discharged from the first exhaust duct member 74 is discharged from the second exhaust duct member 93 and cannot be completely removed by the filter member 100. (UFP) and volatile organic compounds (VOC) adhere to components such as particles that increase in particle size or are heated by the heated air exhausted from the first exhaust duct member 74 to generate ultrafine particle dust (UFP) or volatile By recombining components such as organic compounds (VOC), the amount of ultrafine particle dust (UFP) and the like discharged from the exhaust port 94 of the confluence duct 80 to the outside is greatly reduced.

  As described above, according to the first embodiment, the fixing is performed as compared with the case where the intake duct that is connected to the upstream side of the filter unit inside the exhaust duct and introduces air from the outside of the housing is provided. It is possible to reduce the amount of ultrafine particle dust discharged from the device 40 to the outside.

  Further, according to the first embodiment, as shown in FIGS. 6 and 8, the exhaust port 94 of the merging duct 80 is continuously opened with the auxiliary exhaust opening 98 at the upper portion thereof. Therefore, even when the back surface of the apparatus main body 1a is disposed in the vicinity of a shield such as a wall (not shown), as shown in FIG. Is possible.

Experimental Example Next, the inventor made a prototype of the image forming apparatus 1 as shown in FIG. 1 and evaluated ultrafine particle dust (UFP) discharged from the image forming apparatus 1 to the outside.

  In this evaluation of the ultrafine particle dust, the image forming apparatus 1 was installed in a highly airtight chamber (test environment room), and the image forming apparatus 1 was continuously operated for 10 minutes in a continuous printing operation. Thereafter, the air in the chamber was sucked with a dedicated measuring device, and the amount of ultrafine particle dust (UFP) contained in the exhaust discharged from the image forming apparatus 1 was measured.

  Further, as a comparative example, ultrafine particle dust was evaluated using a conventional image forming apparatus configured such that the second exhaust fan 87 exhausts toward the side surface rather than the back surface of the apparatus main body 1a.

  FIG. 11 is a graph showing the evaluation results of ultrafine particle dust.

  As is apparent from FIG. 11, in the case of the image forming apparatus 1 according to the present embodiment, the ultrafine particle dust (UFP) is about 1/2 to 1/4 compared with the conventional image forming apparatus. It was found that the emission amount can be reduced.

  In the above-described embodiment, an image forming apparatus that forms a monochrome image is described as the image forming apparatus. However, four color toners of yellow (Y), magenta (M), cyan (C), and black (K) are described. Of course, the present invention can be similarly applied to a full-color image forming apparatus for forming an image.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 1a ... Image forming apparatus main body 11 ... Photoconductor drum 14 ... Developing device 40 ... Fixing device 70 ... Air guide passage 74 ... First exhaust duct member 76 ... First exhaust fan 80 ... Confluence duct 87 ... second exhaust fan 93 ... second exhaust duct member 94 ... exhaust port

Claims (4)

Fixing means for heating and fixing a recording medium holding an unfixed image;
A first exhaust unit disposed at one end of the fixing unit along a direction intersecting the conveyance direction of the recording medium, and discharging the air around the fixing unit to the outside;
A second exhaust unit disposed on the downstream side of the fixing unit in the conveyance direction of the recording medium and exhausting ambient air to the outside;
An exhaust duct member that joins the exhaust of the first exhaust means and the exhaust of the second exhaust means and guides it to the exhaust port on the back of the apparatus body;
An image forming apparatus. The exhaust duct member is
A first exhaust duct member for guiding the exhaust of the first exhaust means to the back surface of the apparatus body;
A second exhaust duct member for guiding the exhaust of the second exhaust means to the back surface of the apparatus body;
With
The exhaust of the first exhaust means and the exhaust of the second exhaust means are merged with the first exhaust duct member disposed below the second exhaust duct member immediately before the exhaust port. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein a filter member that removes a specific component in the exhaust is provided at a position immediately before the exhaust port of the exhaust duct member.   4. The image forming apparatus according to claim 1, wherein the exhaust duct member includes an opening for auxiliary exhaust that is opened on an upper surface of the apparatus main body. 5.

Images