JP2009210892A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can efficiently uniformize, without increasing the apparatus size, the temperature of a fixing unit through which recording paper is conveyed with the center in a longitudinal direction as a conveying center. <P>SOLUTION: The image forming apparatus includes: a central ventilation path T1 communicating with the outside of the apparatuses from the central part of the fixing unit 7; an end ventilation path T2 communicating with the outside of the apparatus and the central ventilation path T1 from both longitudinal ends of the fixing unit 7; a central fan 115 and an end fan 119 that create a current of air from the end ventilation path T2 to the central ventilation path T1; and a control section 140 that controls these fans 115 and 118. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus including a fixing unit that thermally fixes an unfixed toner image on a recording sheet conveyed with the center in the longitudinal direction as a conveyance center.

  The image forming apparatus is used for a copying machine, a printer, a facsimile, and a multifunction machine having at least two of these functions. Such an image forming apparatus forms a latent image by selectively exposing the surface of a uniformly charged photosensitive drum according to image information, and develops the formed electrostatic latent image to form a toner. The image is formed by forming an image and transferring the toner image onto a recording sheet. The recording sheet is discharged to a discharge tray after an unfixed toner image is fixed by a fixing unit. Generally, a fixing device melts and fixes unfixed toner on a recording sheet by pressing a heating roller (also referred to as a fixing roller) including a heat source such as a halogen heater against the recording sheet. .

  When the heated surface of the heating roller comes into pressure contact with the recording paper, a part of the heat is radiated through the recording paper. However, the heating roller has a length in the longitudinal direction that is equal to or greater than the maximum width of the transportable recording paper. Therefore, in the image forming apparatus in which the recording paper is conveyed through the fixing device with the longitudinal center as the conveyance center, when the narrow recording paper is conveyed, the area where the recording paper is not pressed, that is, the non-sheet passing area at both ends. This heat is not dissipated through the recording paper. For this reason, both end portions of the heating roller have a higher temperature than the central portion, and temperature unevenness occurs in the surface temperature of the heating roller. In particular, when a wide recording sheet is transported after a narrow recording sheet is transported continuously, the temperature at both ends of the fixing device rises excessively, so that good fixability cannot be obtained and image quality is improved. There is a problem of deterioration. Although the light distribution of the halogen heater as a heat source built in the heating furnace roller is also changed in the longitudinal direction, since the light distribution is not variable, depending on the size and number of sheets of recording paper to be conveyed, Insufficient temperature uniformity.

  Thus, for example, Patent Document 1 discloses an image forming apparatus in which temperature sensors are provided in the vicinity of the end and center of the heating roller. If it is determined that an abnormally high temperature portion has occurred in the heating roller based on the temperature detected by these temperature sensors, the power supply to the heat source in the heating roller is stopped and the heating roller becomes hotter than that. And waited until the heating roller was naturally cooled.

Patent Document 2 discloses an image in which a temperature sensor is provided in the vicinity of the end and center of the heating roller, and a cooling fan that blows cooling air on the surface of the heating roller whose temperature is detected by these temperature sensors. A forming apparatus is disclosed. And the cooling air by the cooling fan corresponding to the said temperature sensor is adjusted with the temperature which the temperature sensor detected.
JP-A-9-274408 (paragraph 0004 of the specification) JP-A-9-274408

  However, in the image forming apparatus disclosed in Patent Document 1, once the power supply to the heat source is stopped, the temperature of the heating roller is lowered, but it takes time for the heat source to restart and re-heat. In addition, there is a problem of inefficiency, which is uneconomical due to excessive heat generation. Further, in the image forming apparatus disclosed in Patent Document 2, it is necessary to dispose a cooling fan so as to blow cooling air on the respective surfaces near the end and the center of the heating roller. For this reason, providing such a cooling fan in the vicinity of the surface of the heating roller has a problem in that the size of the apparatus is increased due to layout restrictions and the like, which is against the demand for downsizing.

  The present invention has been made in view of the above-described problems, and enables image formation in which the temperature of the fixing device to which the recording paper is conveyed with the center in the longitudinal direction being the conveyance center can be efficiently and without increasing the size. An object is to provide an apparatus.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a fixing unit that thermally fixes an unfixed toner image on a recording sheet that is transported with the center in the longitudinal direction as a transport center, and a central portion of the fixing device. A central ventilation path that communicates with the outside of the apparatus, an end ventilation path that communicates with the outside of the apparatus from both longitudinal ends of the fixing device and communicates with the central ventilation path, and a central ventilation path that extends from the end ventilation path. An air flow forming means for forming an air flow and a control unit for controlling the air flow forming means are provided.

  Further, the image forming apparatus according to the present invention is characterized in that the air flow forming means is an exhaust fan that is provided in the central ventilation path and forcibly exhausts air to the outside of the apparatus.

  Furthermore, the image forming apparatus according to the present invention is characterized in that the air flow forming means is an intake fan that is provided in each of the end ventilation paths and forcibly sucks air from outside the apparatus.

  The image forming apparatus according to the present invention includes an air flow forming unit that forms an air flow from the end ventilation path to the central ventilation path, and a control unit that controls the air flow forming unit. Therefore, it is possible to form and control an air flow from both longitudinal ends of the fixing device toward the central portion. When there is a possibility that the temperature at both ends of the fixing device will rise excessively, such as when narrow recording paper is continuously conveyed, an air flow from both longitudinal ends of the fixing device toward the center is formed. Can do. Therefore, by lowering the temperature at both ends where the temperature has increased and raising the temperature at the center, abnormally high temperatures at both ends can be prevented in advance, and the temperature of the fixing device can be made uniform. It becomes possible to prevent deterioration. In addition, when the temperature of the central portion rises, even when narrow recording paper is continuously conveyed, heat generation for raising the temperature of the fixing device can be suppressed, and energy saving can be achieved. Efficient. Moreover, since the central ventilation path and the end ventilation path communicate with the outside, the hot air in these paths can be exhausted outside, or fresh air can be sucked in from the outside without staying inside. . Therefore, it is possible to more easily form an air flow from both ends in the longitudinal direction of the fixing device toward the center.

  Further, according to the image forming apparatus of the present invention, the air flow forming means is an exhaust fan that is provided in the central ventilation path and forcibly exhausts air to the outside of the apparatus. Therefore, it is possible to easily and forcibly form an air flow from both longitudinal ends of the fixing device toward the central portion. Further, since the exhaust fan does not need to be disposed in the vicinity of the surface of the heating roller, it is possible to avoid an increase in the size of the apparatus as in the image forming apparatus disclosed in Patent Document 2.

  Furthermore, according to the image forming apparatus of the present invention, the air flow forming means is an intake fan that is provided in each end ventilation path and forcibly sucks air from outside the apparatus. Therefore, it is possible to easily and forcibly form an air flow from both longitudinal ends of the fixing device toward the central portion. Further, since the air sucked by the intake fan flows into the end ventilation path, the temperature at both ends in the longitudinal direction of the fixing device can be more effectively lowered. In addition, since it is not necessary to dispose the intake fan near the surface of the heating roller, it is possible to avoid an increase in the size of the apparatus as in the image forming apparatus disclosed in Patent Document 2.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. A copy / facsimile multifunction peripheral 100 equipped with an image forming apparatus according to an embodiment of the present invention has a built-in image forming apparatus for forming an image on a recording sheet, as shown in FIG. A main body 110, a reading table 120 functioning as a flatbed scanner for reading an image of an original, and an operation panel 130 for inputting start of image reading and image formation.

  As shown in FIG. 2, the main body 110 is provided with a paper feeding cassette 101 for sequentially supplying recording paper for recording images on the bottom of the apparatus, and above the paper feeding cassette 101. An image forming unit 102 is disposed, and a paper discharge tray 103 is disposed above the image forming unit 102. A conveyance path 104 for conveying recording paper from the paper feed cassette 101 to the paper discharge tray 103 extends upward from one end side of the paper feed cassette 101 to the image forming unit 102 and further extends upward. Then, it is formed so as to bend in the horizontal direction and lead to the paper discharge tray 103.

  The paper feed cassette 101 has a box shape that can store recording paper of various sizes, and is provided at the bottom of the apparatus so that it can be pulled out, so that it can be loaded with recording paper as required. The recording paper stored in the paper feed cassette 101 is always positioned at the paper feed position at one end of the uppermost paper by the guide 101a. A paper feed mechanism 101b including a pickup roller, a reverse roller, and a separation pad is provided at the paper feed position, and the recording paper is fed into the transport path 104 one by one.

  The image forming unit 102 includes a charging device 2, an LED head 3, a developing device 4, a transfer roller 5, and a cleaning device 6 disposed around the photosensitive drum 1, and a conveyance path 104 on the downstream side of the photosensitive drum 1. And a fixing device 7 disposed in the space. Among these, the photosensitive drum 1, the charging device 2, and the cleaning device device 6 are housed in a cartridge as a process unit PU and integrated.

  The photosensitive drum 1 is rotated at a predetermined speed by a motor (not shown), and the surface thereof is charged to a constant voltage by the charging device 2. The charging device 2 is a non-contact corona charging method called a so-called scorotron charger, in which a discharge wire is disposed substantially at the center of a casing electrode forming a half space, and a grid electrode is provided on the photosensitive drum 1 side. The corona discharge is generated by applying a predetermined voltage to the discharge wire, and the amount of ions generated by the corona discharge is controlled by the grid electrode. The charging device 2 may employ another charging device such as a contact roller charging method instead of the non-contact corona charging method.

  The LED head 3 is a so-called self-luminous printer head in which LED arrays are arranged in parallel for the number of recording pixels and light emitted from the LED array is imaged on the surface of the photosensitive drum 1 by a selfoc lens array. The surface of the photosensitive drum 1 is selectively exposed to the body drum 1 based on the image information, and an electrostatic latent image is formed on the surface. The surface of the photosensitive drum 1 charged by the charging device 2 is attenuated by being exposed by the LED head 3, and an electrostatic latent image is formed by a potential difference from the unexposed portion. Further, as the image information, for example, an image of a document read by the reading table 120 functioning as a flatbed scanner is transmitted to the LED head 3 as an electrical signal. As the exposure device, a scanning optical system using a semiconductor laser in addition to the LED head 3 may be employed.

  The developing device 4 includes a supply roller, a development roller, and a toner container. The toner in the toner container is developed through the supply roller due to a difference in bias voltage applied to the supply roller and the development roller from an electric circuit (not shown). A toner layer is formed on the surface of the developing roller. The developing roller on which the toner layer is formed is rotated at a position close to the photosensitive drum 1, and the toner on the developing roller moves to the photosensitive drum 1 due to a potential difference from the electrostatic latent image on the photosensitive drum 1. A toner image is formed on the surface of the photosensitive drum 1 based on the electrostatic latent image. Such a developing device 4 is an example, and selection of magnetic toner or non-magnetic toner, selection of contact development method or non-contact development method, and the like are arbitrary.

  The transfer roller 5 is a roller made of EPDM foam or urethane sponge, and is pressed against the photosensitive drum 1 at a position opposed to the conveyance path 104 so that a bias voltage is applied from an application circuit (not shown). Yes. The recording sheet supplied from the sheet feeding cassette 101 via the conveyance path 104 is nipped by the photosensitive drum 1 and the transfer roller 5 and a bias voltage is applied, so that a toner image formed on the surface of the photosensitive drum 1 is formed. Transferred to recording paper.

  The cleaning device 6 includes a cleaning blade, and removes and collects toner and paper dust remaining on the surface of the photosensitive drum 1. The cleaning blade is pressed against the surface of the photosensitive drum 1 after transfer and a constant voltage is applied from an electric circuit (not shown), thereby removing toner and paper dust remaining on the surface of the photosensitive drum 1 and electrostatic latent. Erase the image. Waste toner and paper dust scraped off by the cleaning blade are transported to the front side of the apparatus by waste toner transport means that is rotationally driven by a motor (not shown) and accumulated in a waste toner collection container (not shown). .

  As shown in FIG. 2 or 3, the fixing device 7 includes a heating roller 71 and a pressure roller 72 that are respectively disposed at positions opposed to the conveyance path 104, and is on a recording sheet conveyed through the conveyance path 104. An unfixed toner image is thermally fixed on the recording. The heating roller 71 is a hollow roller made of aluminum or the like, and a heat source 73 such as a halogen heater that generates heat by power supply from a power supply circuit (not shown) is disposed in the inner space thereof. The heating roller 71 is driven to rotate at a predetermined peripheral speed by a motor (not shown). The pressure roller 72 is rotatably supported by the bearing and is pressed against the heating roller 71 with a predetermined pressing force. The pressure roller 72 is rotated by the rotation of the heating roller 71. When the recording sheet on which the unfixed toner image is transferred is nipped and conveyed between the pressure contact portions of the heating roller 71 and the pressure roller 72, the toner is melted by the heat of the heating roller 71 and pressed by the pressure contact portion. The toner image is fixed by heat. The heating roller 71 and the pressure roller 72 are housed inside a fixing housing 74 made of synthetic resin, which is an exterior housing of the fixing device 7, together with a cleaning roller for cleaning the surface of the heating roller 71. As shown in FIG. 4, the fixing housing 74 also houses a temperature sensor 75 that measures the surface temperature near the center of the heating roller 71.

  Further, as shown in FIG. 3 or FIG. 4, the fixing housing 74 of the fixing device 7 has an opening 74 a, in order to eliminate hot air generated in the fixing device 7 due to heat generated by the heat generation source 73 in the heating roller 71. 74b is formed. The opening 74 a is formed on the side surface of the fixing housing 74 in the longitudinal direction on the side of the discharge tray 103. The openings 74 b are respectively formed on the front side and the back side surface of both ends in the longitudinal direction of the fixing housing 74. The opening 74 a and the opening 74 b communicate with each other in the fixing housing 74.

  As shown in FIG. 2, the recording paper is conveyed from the paper feed cassette 101 along the conveyance path 104 to the image forming unit 102, and after the image is formed by the image forming unit 102, the recording paper is transferred to the paper discharge tray 103. Discharged. The conveyance path 104 is extended substantially upward from the paper feed cassette 101 to the image forming unit 102, and a pair of conveyance rollers 80 for nipping and conveying the recording paper is appropriately provided in the middle. A pair of paper discharge rollers 81 that nip the recording paper and discharge it toward the paper discharge tray 103 are provided at the end of the conveyance path 104. With such a conveyance path 104, a reverse C path is formed from the paper feed cassette 101 to the paper discharge tray 103.

  As shown in FIG. 3, the frame of the main body 110 (see FIG. 1) extends in the front-rear direction (width direction of the recording paper to be conveyed) between the front and rear side walls of the exterior chassis constituting the exterior portion of the frame. And stays 111 connected to each other. The fixing device 7 is held on the vertical piece 111 a of the stay 111 by pins or the like. A vent hole 111 b is formed in the longitudinal center portion of the vertical piece 111 a of the stay 111 in order to release hot air in the fixing device 7 due to exhaust heat of the heating roller 71. The stay 111 includes a horizontal piece 111c extending horizontally from the lower end of the vertical piece 111a to the left (in the direction opposite to the side where the fixing device 7 is held). In the horizontal piece 111c of the stay 111, an ozone discharge slit 111d is formed in order to discharge ozone generated by corona discharge in the charging device 2.

  The central air path T1 is formed by a space surrounded by the stay 111, the central duct 112, and the upper exterior housing 113. The central duct 112 is inside the stay 111 (the side opposite to the side where the fixing unit 7 and the process unit PU (see FIG. 2) are located, and the side defined by the inner surfaces of the vertical piece 111a and the horizontal piece 111c). Is a synthetic resin molded member that communicates the space defined by the center opening 114 with a shape suitable for inducing air, such as a shape that draws an arc from the inside of the stay 111 toward the center opening 114. Has been. The lower surface of the end portion on the stay 111 side of the central duct 112 is placed on the upper end surface of the mounting piece 111e that extends upward from the left end (the side opposite to the side on which the vertical piece 111a is located) of the horizontal piece 111c of the stay 111. As a result, a gap is not formed between the stay 111 and the stay 111. The upper exterior housing 113 is a synthetic resin molding member that forms a part of the exterior housing of the main body 110. The upper exterior housing 113 covers the upper portion of the stay 111 and the central duct 112, and the discharge tray 103 is formed on the upper surface thereof. . The central opening 114 is an opening formed on the left side surface of the exterior housing of the main body 110 and is connected to the opening at the left end of the central duct 112. The central fan 115 forcibly forms an air flow toward the central opening 114 in the central air path T1, and is disposed near the end of the central duct 112 on the central opening 114 side. Yes. As shown in FIG. 4, the central fan 115 is driven by a motor (not shown) controlled by the control unit 140. The ozone filter 116 absorbs ozone that has been sent together with the passing air, and is disposed in the central duct 112 so as to be positioned between the central opening 114 and the central fan 115. The ozone generated in the charging device 2 is discharged to the central air path T1 through the ozone discharge slit 111d, and is guided to the central opening 114 by the central fan 115 together with the air in the central air path T1, and the central opening 114 Is removed by an ozone filter 116 disposed in front of.

  The hot air in the fixing device 7 flows into the central air path T1 through the opening 74a formed in the fixing surface of the fixing housing 74 to the stay 111 and the vent hole 111b formed in the vertical piece 111a of the stay 111, and the central fan Guided by 115 and discharged from the central opening 114 to the outside of the device.

  On the other hand, as shown in FIG. 4, the end air path T <b> 2 is located on the front side and the back side of the fixing device 7 (that is, on both ends in the longitudinal direction), and is formed by a space surrounded by the end duct 117. ing. The end duct 117 is a synthetic resin molding member that communicates the opening 74 b formed on both side surfaces of the fixing device 7 with the end opening 118, and extends from the end opening 118 toward the opening of the fixing device 7. It is formed in a shape suitable for inducing air, such as an arc drawing shape. As shown in FIG. 1, the end opening 118 is an opening formed on the front side surface and the back side surface of the exterior housing of the main body 110, and is connected to the opening at the outer end portion of the end duct 117. Further, the end fan 119 forcibly sucks air from the end opening 118 into the end air path T2, and is disposed in the vicinity of the end of the end duct 117 on the end opening 118 side. ing. The end fan 119 is driven by a motor (not shown) controlled by the control unit 140.

  The control unit 140 performs control so that the surface of the heating roller 71 is maintained at a predetermined temperature uniformly in the longitudinal direction. The control unit 140 performs control based on the surface temperature of the heating roller 71 detected by the temperature sensor 75 and the size and number of recording sheets on which image formation is input from the operation panel 130 (see FIG. 1). The control unit 140 performs control by adjusting the amount of heat generation including turning on / off the heat source 73 and adjusting the air volume of the central fan 115 and the end fan 119 by drive control of a motor (not shown).

  Specific control of the control unit 140 will be described in the case where the horizontal direction of the A4 size is the maximum width of the recording paper on which image formation is possible. For example, when the recording paper on which an image is formed is A3 size and is conveyed in the lateral direction, the surface temperature of the heating roller 71 is considered to be uniform in the longitudinal direction. Therefore, the control unit 140 controls to stop only the heat generating source 73 and the central fan 115 and stop the end fan 119 so that the surface temperature detected by the temperature sensor 75 falls within a predetermined range. On the other hand, when a recording sheet on which an image is formed is narrower than A3 size width, for example, an A4 size recording sheet is conveyed in the vertical direction, the surface temperature of the heating roller 71 is at the center in the longitudinal direction. Is considered to be low and both ends are high. Therefore, the control unit 140 controls the heat source 73 and the central fan 115 to be appropriately driven and also drives the end fan 119 so that the surface temperature detected by the temperature sensor 75 falls within a predetermined range. However, the controller 140 may perform control so as not to drive the end fan 119 when, for example, only a single sheet of A4 size recording paper is transported in the vertical direction without being continuous.

  As described above, the copy / facsimile multifunction peripheral 100 includes the central ventilation path T1, the end ventilation path T2, the central fan 115, the end fan 119, and the control unit 140. For this reason, it is possible to form and control an air flow from both longitudinal ends of the fixing device 7 toward the central portion. For example, when narrow recording paper is continuously conveyed, the air flow from both longitudinal ends of the fixing device 7 toward the central portion is forced when the temperature at both ends of the fixing device 7 may increase excessively. Can be formed. Therefore, by lowering the temperature at both ends where the temperature has risen and raising the temperature at the center, abnormally high temperatures at both ends can be prevented in advance, and the temperature of the fixing device 7 can be made uniform. It is possible to prevent the deterioration of the material. Further, when the temperature of the central portion rises, even when narrow recording paper is continuously conveyed, heat generation for raising the temperature of the fixing device 7 can be suppressed, and energy saving can be achieved. Is efficient. Further, since the central ventilation path T1 and the end ventilation path T2 communicate with the outside of the machine base via the central opening 114 and the end opening 118, the hot air in these paths T1 and T2 does not stay inside. Can exhaust hot air to the outside, or inhale fresh air from the outside. Therefore, it is possible to more easily form an air flow from both longitudinal ends of the fixing device 7 toward the central portion.

  Further, a central fan 115 that forcibly exhausts air to the outside of the machine base is provided in the vicinity of the central opening 114 of the central ventilation path T1. For this reason, it is possible to easily and forcibly form an air flow from both longitudinal ends of the fixing device 7 toward the central portion. Further, since the central fan 115 is disposed in the vicinity of the left end of the machine base, it is possible to avoid an increase in the size of the machine base as in the image forming apparatus disclosed in Patent Document 2.

  Further, two end fans 119 that forcibly intake air from outside the machine base are provided in the vicinity of the end opening 118 of the end ventilation path T2. For this reason, it is possible to easily and forcibly form an air flow from both longitudinal ends of the fixing device 7 toward the central portion. Further, since the air sucked by the end fan 119 flows into the end ventilation path T2, the temperature at both longitudinal ends of the fixing device 7 can be more effectively lowered. Further, since the end fan 119 is disposed on the front side and the back side of the fixing device 7, respectively, avoiding the increase in the size of the machine base as in the image forming apparatus disclosed in Patent Document 2. Is possible.

  Note that the configuration of the copy / facsimile multifunction peripheral 100 shown in this embodiment is merely one aspect of the image forming apparatus according to the present invention, and various modifications can be made without departing from the scope of the present invention. is there. For example, the case where both the central fan 115 and the two end fans 119 are provided has been described. However, only the central fan 115 or the two end fans 119 may be provided. Since the central air path T1 and the end air path T2 communicate from the end opening 118 to the central opening 114 via the inside of the fixing device 7, the fixing is performed only by either the central fan 115 or the end fan 119. It is possible to create an air flow from both ends of the vessel 7 to the center.

  Further, the case has been described in which the end air path T <b> 2 that connects the end opening 118 and the opening 74 b on the side surface of the fixing device 7 is formed by the end duct 117. However, the end air path T2 may be formed by a gap formed by an existing member without providing a dedicated member for forming the end air path T2 such as the end duct 117.

  Moreover, the case where only the temperature sensor 75 that measures the surface temperature in the vicinity of the central portion is provided as the temperature sensor that measures the surface temperature of the heating roller 71 has been described. However, a temperature sensor for measuring the surface temperature in the vicinity of the longitudinal end of the heating roller 71 is provided, and the control unit 140 performs control based on the temperature sensor or the surface temperature detected by the temperature sensor and the temperature sensor 75. May be.

  Further, in the present embodiment, the mode in which the image forming apparatus is implemented as the copy / facsimile multifunction peripheral 100 has been described. However, the image reading apparatus is not limited to this, and a printer, a facsimile machine, a copier, and any of these multifunction peripherals. Etc. are applicable.

1 is a schematic perspective view showing an external appearance of a copy / facsimile multifunction peripheral 100 according to an embodiment of the present invention. 1 is a schematic longitudinal sectional view showing a main body 110 of a copy / facsimile multifunction peripheral 100. FIG. FIG. 3 is a schematic longitudinal sectional view showing an enlargement of the vicinity of the fixing device 7. 2 is a schematic perspective view and a block diagram showing a fixing device 7 and air paths T1, T2, and the like. FIG.

Explanation of symbols

7 Fixing Unit 71 Heating Roller 75 Temperature Sensor 100 Copy / Facsimile Multifunction Machine (Image Forming Apparatus)
110 Main body 112 Central duct 113 Upper exterior housing 114 Central opening 115 Central fan (air flow forming means, exhaust fan)
117 End duct 118 End opening 119 End fan (air flow forming means, intake fan)
140 Control unit T1 Central ventilation path T2 End ventilation path

Claims (3)

A fixing device for thermally fixing an unfixed toner image on a recording sheet conveyed with the longitudinal center as a conveyance center;
A central ventilation path communicating from the center of the fixing device to the outside of the apparatus;
An end ventilation path that communicates from both longitudinal ends of the fixing device to the outside of the apparatus and also communicates with the central ventilation path;
An air flow forming means for forming an air flow from the end ventilation path to the central ventilation path;
An image forming apparatus comprising: a control unit that controls the air flow forming unit.   The image forming apparatus according to claim 1, wherein the air flow forming unit is an exhaust fan that is provided in the central ventilation path and forcibly exhausts air to the outside of the apparatus.   The image forming apparatus according to claim 1, wherein the air flow forming unit is an intake fan that is provided in each of the end ventilation paths and forcibly sucks air from outside the apparatus.

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