JP2023169735A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can reliably collect particulate substances by using a cyclone separator.SOLUTION: An image forming apparatus comprises: a cyclone separator 81 that forms circulating airflow, and can separate particulate substances included in air from the air through centrifugation; a switching mechanism unit 330 that can change a speed of the airflow in the cyclone separator 81 to switch a condition for the centrifugation between a first separation mode and a second separation mode with a higher centrifugation efficiency than the first separation mode; and a control unit that determines a generation amount of the particulate substances in the image forming apparatus, and controls the switching mechanism unit 330 based on a result of the determination.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image forming apparatus.

For example, Japanese Patent Application Publication No. 2017-90645 (Patent Document 1) discloses a duct portion that sucks toner-containing air, a shielding member that changes the opening area of the inlet of the duct portion, and a shielding member that communicates with the duct portion and that contains toner-containing air. A cyclone section that centrifugally separates toner from the air, a collection section that collects the toner separated by the cyclone section, a filter section that passes air from the cyclone section, a fan that generates a flow of air containing toner, and a collection section. An image forming apparatus is disclosed that includes a control section that increases the air volume of a fan and narrows the opening area of a duct section using a shielding member as the amount of toner collected increases.

Furthermore, Japanese Patent Application Publication No. 2017-191227 (Patent Document 2) discloses an image forming apparatus that includes a duct, a heat source that heats air flowing inside the duct, and a fixing device. The duct has a communication portion downstream of the heat source that can draw airflow from the fixing device into the duct.

Furthermore, Japanese Patent Laid-Open No. 2010-2803 (Patent Document 3) describes a fixing device, an exhaust duct for exhausting air containing particulate dust near the fixing device, and a suction fan that sucks air into the exhaust duct. An image forming apparatus is disclosed which includes: a cyclone dust collecting means provided downstream of a suction fan; and an electrostatic dust collecting means provided downstream of the cyclone dust collecting means.

JP2017-90645A Japanese Patent Application Publication No. 2017-191227 Japanese Patent Application Publication No. 2010-2803

As disclosed in the above-mentioned Patent Document 1, an image forming apparatus using a cyclone separator as a means for collecting particulate matter such as toner is known. A cyclone separator creates a swirling air stream and separates particulate matter contained therein from the air by centrifugation.

However, since the amount of particulate matter generated inside an image forming apparatus changes every moment, there is a possibility that the cyclone separator may not be able to reliably collect particulate matter at the timing when the amount of particulate matter increases. .

Furthermore, a plurality of types of particulate matter having different particle sizes are generated at various timings inside the image forming apparatus. For example, a fixing device is provided with a fixing nip portion that heats and presses a recording medium such as a sheet of paper using a roller member made of a silicon-based material. By passing the recording medium through the fixing nip, the toner is melted and fixed to the recording medium. At this time, ultra-fine particles (UFP) with a particle size of 100 nm or less are generated from the heated silicon-based material. Furthermore, floating toner having a particle size larger than ultrafine particles is generated inside the image forming apparatus.

When a plurality of types of particulate matter with different particle sizes are generated in this way, there is a possibility that the cyclone separator cannot reliably collect all of these types of particulate matter.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide an image forming apparatus that can reliably collect particulate matter using a cyclone separator.

[1] An image forming apparatus comprising: a cyclone separator that forms a swirling air flow and is capable of separating particulate matter contained in the air from the air by centrifugation; a switching mechanism unit capable of switching the centrifugal separation conditions between a first separation mode and a second separation mode in which the efficiency of the centrifugation is higher than that of the first separation mode by changing the speed; An image forming apparatus, comprising: a control section that determines the amount of particulate matter generated in the image forming apparatus, and controls the switching mechanism section based on the determination result.

According to the image forming apparatus configured in this way, by relatively reducing the speed of the air flow in the cyclone separator by the switching mechanism, a small centrifugal force is applied to the particulate matter contained in the air. , the centrifugation conditions are switched to the first separation mode. In addition, by relatively increasing the speed of the air flow in the cyclone separator using the switching mechanism, a large centrifugal force is applied to the particulate matter contained in the air, and the centrifugal separation conditions are changed to the first separation mode. Switch to the second separation mode, which has higher centrifugal efficiency. In this case, the control section determines the amount of particulate matter generated in the image forming apparatus and controls the switching mechanism section based on the determination result, so the centrifugation conditions are set according to the amount of particulate matter generated. You can choose. Thereby, particulate matter can be reliably collected by the cyclone separator.

[2] The particulate matter includes a first particulate matter and a second particulate matter having a smaller particle diameter than the first particulate matter, and the control unit is configured to control the particulate matter in the image forming apparatus. 2. The image forming apparatus according to [1], wherein the switching mechanism unit is controlled to switch the centrifugation conditions to the second separation mode when it is determined that the amount of generated particulate matter increases.

According to the image forming apparatus configured in this way, by switching the centrifugal separation conditions to the second separation mode and relatively increasing the speed of the air flow in the cyclone separator, the second particulate matter contained in the air is removed. Apply a large centrifugal force to a substance. Thereby, the second particulate matter having a small particle size can be recovered more reliably.

[3] The cyclone separator has a cyclone main body section defining an internal space for forming the air flow, and an intake passage communicating with the internal space, and the air containing particulate matter is passed through the intake passage. an intake section for introducing air into the internal space, and the switching mechanism section is arranged in the intake passage and is connected to a door section that can be opened and closed, and is connected to the door section and causes the door section to be opened and closed. and an actuator, the control section is arranged such that when switching the centrifugal separation conditions to the first separation mode, the door section is placed in a first position where the intake passage opens with a first area, When switching the separation condition to the second separation mode, the actuator is controlled so that the door is placed in a second position in which the intake passage opens with a second area smaller than the first area. The image forming apparatus according to [1] or [2].

According to the image forming apparatus configured in this way, when the centrifugal separation conditions are switched to the first separation mode, the air intake passage opens with a relatively large first area, so that the speed of the air flow in the cyclone separator increases. When the centrifugal separation conditions are switched to the second separation mode, the air intake passage opens with a relatively small second area, so the speed of the air flow in the cyclone separator increases. Therefore, the centrifugal separation conditions can be switched between the first separation mode and the second separation mode through the opening/closing operation of the door.

[4] The cyclone main body portion extends around a predetermined central axis and includes a peripheral wall portion surrounding the internal space, and the intake portion extends in a tangential direction of the peripheral wall portion around the predetermined central axis. , a first opposing wall part continuous to the peripheral wall part, and a second opposing wall part facing the first opposing wall part with the intake passage in between, and the door part is arranged in the first position and the second opposing wall part. The image forming apparatus according to [3], wherein the intake passage is provided so as to open between the first opposing wall part and the door part, regardless of which position the image forming apparatus is disposed.

According to the image forming apparatus configured in this way, the air introduced into the internal space of the cyclone main body through the intake passage is controlled regardless of whether the door is placed in the first position or the second position. , it can flow smoothly along the peripheral wall.

[5] The switching mechanism unit includes a first fan, and includes a first blower device that introduces air into the cyclone separator as the first fan rotates, and the control unit controls the centrifugal separation. When switching the conditions to the first separation mode, the first fan rotates at a first rotation speed (rpm), and when switching the centrifugation conditions to the second separation mode, the first fan rotates at a first rotation speed (rpm). The image forming apparatus according to [1] or [2], wherein the first air blower is controlled to rotate at a second rotation speed (rpm) higher than the first rotation speed (rpm).

According to the image forming apparatus configured in this way, when the centrifugal separation conditions are switched to the first separation mode, the air volume sent out from the first fan becomes relatively small, so that the air flow in the cyclone separator is reduced. When the speed of the centrifugal separation mode is changed to the second separation mode, the flow rate of the air sent out from the first fan becomes relatively large, so that the speed of the air flow in the cyclone separator becomes large. Therefore, the centrifugal separation conditions can be switched between the first separation mode and the second separation mode by controlling the rotation speed of the first fan in the first blower.

[6] The cyclone separator includes a cyclone main body that partitions and forms an internal space for forming the air flow, and a cyclone main body that is connected to the cyclone main body and that is configured to introduce air containing particulate matter into the internal space. The switching mechanism includes a first intake part and a second intake part connected to the cyclone main body, and the switching mechanism has a second fan, and as the second fan rotates, the second intake part is connected to the second intake part. a second blower device for introducing air into the cyclone separator; the control unit stops the second fan when switching the centrifugal separation conditions to the first separation mode; The image forming apparatus according to [1] or [2], wherein the second blower is controlled so that the second fan rotates when the second fan is switched to the second separation mode.

According to the image forming apparatus configured in this way, when switching the centrifugation conditions to the first separation mode, only the air from the first intake section is introduced into the internal space of the cyclone main body. When the speed of the air flow becomes small and the centrifugal separation conditions are switched to the second separation mode, air from the second intake part is introduced into the internal space of the cyclone body in addition to the air from the first intake part. This increases the airflow velocity in the cyclone separator. Therefore, the centrifugal separation conditions can be switched between the first separation mode and the second separation mode by controlling the rotation of the second fan in the second blower.

[7] The cyclone separator further includes a fixing device and a duct through which air flows for cooling the fixing device, and the cyclone separator is provided in the duct and is arranged downstream of the air flow in the duct with respect to the fixing device. The image forming apparatus according to any one of [1] to [6], which is disposed on the side.

According to the image forming apparatus configured in this way, particulate matter that has entered the duct from the fixing device can be reliably collected by the cyclone separator.

[8] The image forming apparatus according to [7], wherein the duct forms a circulation path through which air circulates.

According to the image forming apparatus configured in this manner, the particulate matter that has entered the duct from the fixing device can be reliably collected by the cyclone separator while preventing the particulate matter from being released outside the duct. I can do it.

[9] The particulate matter includes floating toner and ultra fine particles (UFP) generated in the fixing device, and the fixing device includes a fixing member and heats the fixing member to a target temperature. After that, the toner image is fixed to the recording medium by bringing the fixing member into pressure contact with the recording medium on which the toner image has been formed, and the control section is configured to cause the image forming apparatus to fix the toner image on the recording medium by pressing the fixing member against the recording medium on which the toner image is formed, Determining whether or not the generation amount of fine particles is in an initial burst period in which the amount of generated particles increases rapidly, and when determining that it is in the initial burst period, switching the conditions of the centrifugation to the second separation mode. The image forming apparatus according to [7] or [8], which controls the switching mechanism section.

According to the image forming apparatus configured in this manner, ultrafine particles can be collected more reliably during the initial burst period in which the amount of ultrafine particles with small particle diameters generated rapidly increases.

[10] The control unit determines that the elapsed time from when the power of the image forming apparatus is turned on or from the time when the fixing member returns from a standby state where the temperature is lower than the target temperature is within a predetermined time range. The image forming apparatus according to [9], wherein the image forming apparatus determines that the image forming apparatus is in the initial burst period.

According to the image forming apparatus configured in this way, it is possible to easily determine whether or not the initial burst period is in progress.

[11] Further comprising a temperature detection section that detects the temperature of the fixing member, the control section may cause the temperature of the fixing member detected by the temperature detection section to rise and the amount of the ultrafine particles to be generated to rapidly increase. The image forming apparatus according to [9] or [10], wherein the image forming apparatus determines that the initial burst period is within a predetermined time after reaching a threshold temperature corresponding to a temperature at which the burst temperature starts.

According to the image forming apparatus configured in this way, it is possible to easily determine whether or not the initial burst period is in progress.

As described above, according to the present invention, it is possible to provide an image forming apparatus that can reliably collect particulate matter using a cyclone separator.

1 is a sectional view showing an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a sectional view showing the image forming apparatus as seen in the direction of arrows on the line II-II in FIG. 1. FIG. FIG. 3 is a sectional view showing the cyclone separator (first separation mode) as seen in the arrow direction on the line III-III in FIG. 2; 3 is a cross-sectional view showing the cyclone separator (second separation mode) as seen in the arrow direction on the line III-III in FIG. 2. FIG. FIG. 2 is a block diagram showing a control system of the image forming apparatus. FIG. 3 is a diagram showing a change over time in the amount of UFP generated when the fixing device is driven. 7 is a flowchart showing the operation of switching processing between the first separation mode and the second separation mode. 12 is a flowchart illustrating a modification of the operation of switching processing between the first separation mode and the second separation mode. 9 is a flowchart showing the operation of switching processing between the first separation mode and the second separation mode in the modification shown in FIG. 8; It is a side view which shows the cyclone separator (1st separation mode) provided with the switching mechanism part in a 2nd modification. 11 is a side view showing the cyclone separator in the arrow direction on the line XI-XI in FIG. 10. FIG. It is a side view which shows the cyclone separator (2nd separation mode) provided with the switching mechanism part in a 2nd modification. 13 is a side view showing the cyclone separator in the arrow direction on the line XIII-XIII in FIG. 12. FIG. FIG. 7 is a cross-sectional view showing a modification of the cooling structure of the fixing device. 15 is a perspective view schematically showing an image forming apparatus including a cooling structure for the fixing device in FIG. 14. FIG.

Embodiments of the invention will be described with reference to the drawings. In addition, in the drawings referred to below, the same numbers are attached to the same or corresponding members.

(Embodiment 1)
FIG. 1 is a sectional view showing an image forming apparatus according to Embodiment 1 of the present invention. Referring to FIG. 1, image forming apparatus 100 in this embodiment is, for example, an electrophotographic image forming apparatus such as a copying machine. The image forming apparatus 100 is a so-called tandem color image forming apparatus that forms a full-color image by arranging a plurality of photoreceptors in the vertical direction facing one intermediate transfer belt.

The image forming apparatus 100 includes an image forming section 10 (10Y, 10M, 10C, 10K), a fixing device 50, and an exterior body 61.

The exterior body 61 consists of a housing and forms the external appearance of the image forming apparatus 100. The exterior body 61 has a rectangular parallelepiped shape. The exterior body 61 houses the image forming section 10, the fixing device 50, and the like. The exterior body 61 defines an interior space 63 therein. The interior space 63 is a space surrounded by the exterior body 61 and sealed except for a ventilation hole, a paper conveyance port, and the like.

The image forming section 10 forms an image. The image forming section 10Y, the image forming section 10M, the image forming section 10C, and the image forming section 10K form yellow (Y), magenta (M), cyan (C), and black (K) images, respectively.

The image forming section 10Y includes a photosensitive drum 1Y, a charging section 2Y, an optical writing section 3Y, a developing device 4Y, and a drum cleaner 5Y. The charging section 2Y, the optical writing section 3Y, the developing device 4Y, and the drum cleaner 5Y are arranged around the photosensitive drum 1Y. Similarly, the image forming section 10M includes a photoconductor drum 1M, a charging section 2M, an optical writing section 3M, a developing device 4M, and a drum cleaner 5M, and the image forming section 10C includes a photoconductor drum 1C. , a charging section 2C, an optical writing section 3C, a developing device 4C, and a drum cleaner 5C, and the image forming section 10K includes a photosensitive drum 1K, a charging section 2K, an optical writing section 3K, , a developing device 4K, and a drum cleaner 5K.

The surfaces of the photoreceptor drums 1Y, 1M, 1C, and 1K are uniformly charged by the charging sections 2Y, 2M, 2C, and 2K, and the photoreceptor drums are exposed by scanning exposure by the optical writing sections 3Y, 3M, 3C, and 3K. Latent images are formed on the drums 1Y, 1M, 1C, and 1K. Further, the developing devices 4Y, 4M, 4C, and 4K develop the latent images on the photoreceptor drums 1Y, 1M, 1C, and 1K by developing them with toner. As the toner, a wax-containing toner in which toner particles contain a release agent is used. As a result, a toner image of a predetermined color corresponding to any one of yellow, magenta, cyan, and black is formed on the photoreceptor drums 1Y, 1M, 1C, and 1K. The toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K are sequentially transferred to predetermined positions on the rotating intermediate transfer belt 6 by primary transfer rollers 7Y, 7M, 7C, and 7K.

The toner image of each color transferred onto the intermediate transfer belt 6 is transferred by a secondary transfer roller 9 onto a paper P serving as a recording medium, which is supplied at a predetermined timing by a paper feeding device 20, which will be described later. The secondary transfer roller 9 is arranged so as to be in pressure contact with the intermediate transfer belt 6.

Paper P is stored in a paper feed tray 21 of a paper feed device 20 . The paper P accommodated in the paper feed tray 21 is taken in by the paper feed section 22 and sent out to the conveyance path. Further, the paper P is stored in a paper feed tray included in an external paper feed device (not shown) connected to the image forming apparatus 100. The paper P held by the external paper feeding device is fed from the external paper feeding device to the image forming apparatus 100 and sent out to the main conveyance path 41 .

In the main conveyance path 41, on the upstream side of the transfer position where the toner image is transferred to the paper P (that is, the pressure contact position between the intermediate transfer belt 6 and the secondary transfer roller 9), there are a plurality of conveyance means for conveying the paper P. is provided. The conveyance means is constituted by a pair of rollers pressed together, and conveys the paper P by rotating at least one of the rollers through a drive means such as an electric motor. In this embodiment, intermediate conveyance rollers 23 to 25, a loop roller 26, and a registration roller 27 are provided as conveyance means from the upstream side to the downstream side in the paper conveyance direction.

The fixing device 50 fixes the toner image onto the paper P onto which the toner image has been transferred by the secondary transfer roller 9 .

The fixing device 50 includes a case body 56, a pair of fixing members 51 and 52, a heater (not shown), and a temperature sensor 320 (see FIG. 5 below).

The case body 56 consists of a housing. The case body 56 accommodates a pair of fixing members 51 and 52 and a heater (not shown). The case body 56 has an opening 58 for transporting the paper P toward a fixing nip section to be described later, and an exit port 59 for carrying the paper P out from the fixing nip section to be described later.

The pair of fixing members 51 and 52 are made of roller bodies, for example. The rotation shaft 110 of the fixing member 51 and the rotation shaft 120 of the fixing member 52 extend in the front-rear direction of the image forming apparatus 100. The pair of fixing members 51 and 52 are pressed against each other to form a fixing nip. The heater is provided to heat one or both of the pair of fixing members 51 and 52 (fixing member 51 in this embodiment). The temperature sensor 320 is provided as a temperature detection section that detects the surface temperature of the fixing member 51. While the paper P is conveyed through the fixing nip section, the toner image is fixed on the paper P by being pressurized and heated by a pair of fixing members 51 and 52.

The paper P that has been subjected to the fixing process by the fixing device 50 is discharged to a paper discharge tray 29 outside the exterior body 61 by a paper discharge roller 28 .

When forming an image on the back side of the paper P, the paper P after the image formation on the front side of the paper P is conveyed to the reversing conveyance path 42 by the switching gate 55. The reversing conveyance path 42 is a conveyance path for inverting and conveying the sheet P after fixing. A reversing roller (switchback roller) 33 is provided in the reversing conveyance path 42 .

The reversing rollers 33 nip the transported paper P and then reverse the paper P to reverse the paper P and send it out to the paper refeed transport path 43 . The paper P sent out to the paper refeed transport path 43 is transported by a plurality of paper refeed transport means and returned to the transfer position.

FIG. 2 is a sectional view showing the image forming apparatus as seen in the direction of the arrows on the line II-II in FIG. Referring to FIGS. 1 and 2, image forming apparatus 100 further includes a duct 210 and a first air blower 66.

The duct 210 forms an air flow path 90. Air for cooling the fixing device 50 flows through the air flow path 90 . The duct 210 (air flow path 90) extends in the front-rear direction of the image forming apparatus 100. Duct 210 is connected to fixing device 50. The duct 210 is connected to the case body 56. The first duct 71 and the case body 56 are connected so that the top surface 57 of the case body 56 is exposed to the air flow path 90. The duct 210 is provided on the fixing device 50.

The duct 210 is provided with an intake port 211 and an exhaust port 212. The intake port 211 and the exhaust port 212 are made up of openings that penetrate the duct 210 and open the air flow path 90 to the outside. The duct 210 is connected to the fixing device 50 between the intake port 211 and the exhaust port 212 .

The first blower device 66 is provided on the path of the air flow path 90. The first air blower 66 is, for example, a propeller fan. The first blower 66 includes a first fan 67 . When the first blower device 66 is driven, air is taken into the duct 210 through the intake port 211 as the first fan 67 rotates. The air cools the fixing device 50 while flowing through the air flow path 90 . Air that has become hot due to cooling of the fixing device 50 is discharged to the outside of the duct 210 through the exhaust port 212 .

The fixing device 50 becomes hot during the above-described toner image fixing process. Since the fixing device 50 is cooled by the air flowing through the air flow path 90, equipment such as the image forming unit 10 housed in the exterior body 61 is prevented from being damaged by heat from the fixing device 50.

On the other hand, various particulate matter enters into the duct 210. For example, the fixing members 51 and 52 in the fixing device 50 are made of a silicon-based material because they require heat resistance and durability. In this case, as the fixing members 51 and 52 are heated during the toner image fixing process, ultra-fine particles (UFP) with a particle size of 100 nm or less are generated. The UFP generated in the fixing device 50 enters the duct 210 through a minute gap formed in the case body 56 or a minute gap created between the case body 56 and the duct 210. In addition to the UFP, toner floating in the interior space 63 enters the duct 210. The toner has a larger particle size than the UFP. The particle size of the toner is, for example, in the range of 3 μm or more and 12 μm or less as a volume-based median diameter.

3 and 4 are cross-sectional views showing the cyclone separator as seen in the arrow direction on the line III-III in FIG. 2. Referring to FIGS. 2 to 4, image forming apparatus 100 further includes a cyclone separator 81.

Cyclone separator 81 is provided on the path of air discharged from duct 210. The air discharged from the duct 210 passes through the cyclone separator 81 and is discharged outside the image forming apparatus 100 . Cyclone separator 81 may be provided on the path of air flow path 90 within duct 210.

The cyclone separator 81 uses centrifugal force to separate the above-mentioned particulate matter contained in the air from the air. The cyclone separator 81 as a whole has a cylindrical shape centered on a predetermined central axis 101. The cyclone separator 81 is provided with a predetermined central axis 101 extending in the vertical direction.

The cyclone separator 81 includes a cyclone main body 84 , a first intake section 82 , an exhaust section 83 , and a recovery section 85 .

The cyclone main body 84 forms an internal space 91 that forms an air flow that swirls around a predetermined central axis 101 . The internal space 91 has a cylindrical shape centered on a predetermined central axis 101, and has a conical shape that tapers downward, particularly at a position near the lower end in the axial direction of the predetermined central axis 101. The cyclone main body portion 84 has a peripheral wall portion 92 . The peripheral wall portion 92 extends around the predetermined central axis 101 and surrounds the internal space 91 .

The first intake section 82 is connected to a cyclone main body section 84. The first intake section 82 is connected to the outer peripheral surface of the cyclone main body section 84. The first intake section 82 is connected to a position near the upper end of the cyclone main body section 84 in the axial direction of the predetermined central axis 101 . The first intake portion 82 forms an intake passage 95 . The intake passage 95 communicates with the internal space 91. The intake passage 95 extends in a tangential direction of the peripheral wall portion 92 centered on the predetermined central axis 101 . Air containing particulate matter is introduced into the internal space 91 through the first intake section 82 .

The first intake section 82 has a rectangular opening cross section. The first intake section 82 has a first opposing wall section 93 and a second opposing wall section 94. The first opposing wall portion 93 extends in a tangential direction of the peripheral wall portion 92 centered on the predetermined central axis 101 and is continuous with the peripheral wall portion 92 . The second opposing wall 94 faces the first opposing wall 93 with the intake passage 95 in between. The second opposing wall 94 is arranged parallel to the first opposing wall 93.

The exhaust section 83 is connected to the cyclone main body section 84. The exhaust portion 83 has a cylindrical shape (cylindrical shape) extending in the axial direction of the predetermined central axis 101 . The exhaust portion 83 extends on the predetermined central axis 101 . The exhaust section 83 penetrates the top of the cyclone main body section 84 and opens in the internal space 91 . The exhaust section 83 forms an exhaust passage for exhausting air from the internal space 91.

The collection unit 85 is made of a box that can accommodate particulate matter. The recovery section 85 is connected to the lower end of the cyclone main body section 84. The recovery section 85 is provided in a detachable manner with respect to the cyclone main body section 84.

Air introduced into the internal space 91 of the cyclone main body part 84 through the first intake part 82 flows in a spiral shape around a predetermined central axis 101 . During this time, particulate matter contained in the air gathers on the peripheral wall portion 92 of the cyclone main body portion 84 due to centrifugal force, moves downward while moving in the circumferential direction of the predetermined central axis 101, and is separated from the air. The separated particulate matter is collected in the collection section 85. The air from which particulate matter has been separated is reversed in the axial direction of the predetermined central axis 101 and is discharged to the outside of the cyclone body 84 through the exhaust section 83 .

Image forming apparatus 100 further includes a switching mechanism section 330. The switching mechanism section 330 changes the centrifugal separation conditions between a first separation mode 330A and a second separation mode with higher centrifugal separation efficiency than the first separation mode 330A by changing the speed of air flow in the cyclone separator 81. It is configured to be switchable between modes 330B and 330B.

3 shows the switching mechanism section 330 in the first separation mode 330A, and FIG. 4 shows the switching mechanism section 330 in the second separation mode 330B.

In this embodiment, the switching mechanism section 330 includes a door section 86 and an actuator 88. The door portion 86 is arranged in the intake passage 95.

The door portion 86 can be opened and closed. The door portion 86 has a shaft portion 87 . The shaft portion 87 extends axially parallel to the predetermined central axis 101 . The shaft portion 87 is rotatably supported by the first intake portion 82 at both ends in the axial direction of the predetermined central axis 101 . The shaft portion 87 is provided at a position adjacent to the second opposing wall portion 94 . The door portion 86 rotates around the shaft portion 87 during opening and closing operations. As the door section 86 opens and closes, the opening area S of the intake passage 95 changes.

Actuator 88 is connected to door portion 86 . The actuator 88 opens and closes the door 86. The actuator 88 rotates the door portion 86 about the shaft portion 87 . Actuator 88 may be, for example, a motor or an electric cylinder.

In the first separation mode 330A shown in FIG. 3, the door portion 86 is placed at a first position 86A where the intake passage 95 opens with a first area Sa. The door portion 86 extends from the shaft portion 87 in parallel to the air flow in the intake passage 95. The door portion 86 is arranged along the second opposing wall portion 94.

In the second separation mode 330B shown in FIG. 4, the door portion 86 is placed at a second position 86B where the intake passage 95 opens with a second area Sb smaller than the first area Sa. The door portion 86 extends from the shaft portion 87 in a diagonal direction with respect to the air flow in the intake passage 95. The door portion 86 is disposed such that as it goes from the shaft portion 87 toward the downstream side of the air flow in the intake passage 95, it becomes further away from the second opposing wall portion 94 and closer to the first opposing wall portion 93. The door portion 86 partially closes the intake passage 95 on the second opposing wall portion 94 side.

The door portion 86 is provided so that the intake passage 95 opens between the first opposing wall portion 93 and the door portion 86 regardless of whether the door portion 86 is placed in the first position 86A or the second position 86B. There is. That is, when the door section 86 is arranged at the first position 86A, the intake passage 95 opens between the first opposing wall section 93 and the door section 86, and when the door section 86 is arranged at the second position 86B. , the intake passage 95 opens between the first opposing wall portion 93 and the door portion 86 .

When the door portion 86 is disposed at the first position 86A, the intake passage 95 opens with a relatively large first area Sa, so the speed of air flow in the internal space 91 of the cyclone separator 81 becomes small. As a result, a small centrifugal force is applied to the air spirally flowing through the internal space 91, and the centrifugal separation conditions are switched to the low-efficiency first separation mode 330A. On the other hand, when the door portion 86 is disposed at the second position 86B, the intake passage 95 opens with a relatively small second area Sb, so the flow rate of air supplied to the cyclone separator 81 is constant. Under certain conditions, the velocity of the air flow in the interior space 91 increases. As a result, a large centrifugal force is applied to the air spirally flowing through the internal space 91, and the centrifugal separation conditions are switched to the highly efficient second separation mode 330B.

In this embodiment, the intake passage 95 opens between the first opposing wall 93 and the door 86 regardless of whether the door 86 is placed in the first position 86A or the second position 86B. Therefore, the air introduced into the internal space 91 through the intake passage 95 can flow smoothly along the peripheral wall portion 92.

FIG. 5 is a block diagram showing a control system of the image forming apparatus. Referring to FIGS. 1 and 5, control unit 11 controls image forming apparatus 100 in an integrated manner. The control unit 11 includes a CPU 501 , a communication interface (I/F) unit 502 , a ROM (Read Only Memory) 503 , a RAM (Random Access Memory) 504 , and an image data storage unit 505 .

The communication I/F section 502 is an interface for connecting to a LAN such as a LAN card or a LAN board. The ROM 503 stores programs for controlling the image forming section 10, paper feeding section 22, fixing device 50, and the like. The ROM 503 further stores a program for executing switching processing between the first separation mode 330A and the second separation mode 330B by the switching mechanism section 330 (actuator 88).

The RAM 504 is used as a work area when the CPU 501 executes a program. The image data storage unit 505 stores image data for printing input via the communication I/F unit 502. By executing various programs stored in the ROM 503, the CPU 501 controls the operations of various devices such as the image forming unit 10, the paper feeding unit 22, and the fixing device 50, and controls the operation of the first separation mode 330A and the second separation mode. It also executes mode 330B switching processing.

The control unit 11 determines the amount of particulate matter generated in the image forming apparatus 100, and controls the switching mechanism unit 330 (actuator 88) based on the determination result. When the control unit 11 determines that the amount of UFP generated in the image forming apparatus 100 increases, it controls the switching mechanism unit 330 (actuator 88) to switch the centrifugation conditions to the second separation mode 330B.

The switching process between the first separation mode 330A and the second separation mode 330B by the control unit 11 will be specifically described below.

FIG. 6 is a diagram showing changes over time in the amount of UFP generated when the fixing device is driven. Referring to FIG. 6, the amount of UFP generated in fixing device 50 and the surface temperature of fixing member 51 after the start of warm-up after power-on of image forming apparatus 100 are measured by a particle counter and a temperature sensor, respectively. Measured using 320.

In the figure, a curve 401 shows changes in the amount of UFP generated over time, and a curve 402 shows changes in the surface temperature of the fixing member 51 over time. The temperature Ts corresponds to the initial burst generation start temperature, which will be described later.

After the power is turned on, the surface temperature of the fixing member 51 reaches approximately 25 seconds after the warm-up of the fixing member 51 starts and before the target temperature (here, 210° C.) is reached. When the temperature reached 154° C.), the amount of UFP generated begins to rise rapidly, and then the amount of UFP generated reaches its peak. After the amount of UFP generated reaches its peak (here, after the temperature of the fixing member 51 reaches the target temperature and approximately 55 seconds after the start of warm-up), the amount of UFP generated rapidly decreases. do. After the sudden drop in the amount of UFP generated ends (here, approximately 2 minutes after the start of warm-up), the amount of UFP generated becomes approximately constant.

As described above, the period of the initial burst in which the UFP rapidly increases from the time when the amount of UFP generated starts to rise rapidly until the end of the rapid decline is hereinafter referred to as the "initial burst period". According to the present invention, the initial burst period occurs when the fixing member 51 is warmed up from a temperature lower than the temperature at which the amount of UFP generation starts to rapidly increase (hereinafter referred to as "initial burst generation start temperature") to a target temperature. This was confirmed by test results conducted by researchers.

FIG. 7 is a flowchart showing the operation of switching processing between the first separation mode and the second separation mode.

Referring to FIG. 7, image forming apparatus 100 is powered on (S601). The control unit 11 controls the switching mechanism unit 330 (actuator 88) so that the door unit 86 is placed at the first position 86A (first separation mode 330A). The control unit 11 starts energizing the heater for heating the fixing member 51, and starts warming up the fixing member 51 (S602). The control unit 11 starts measuring the elapsed time (t1) from the start of warm-up (step S603).

The control unit 11 determines whether t1 has reached the initial burst generation start time (step S604).

The "initial burst generation start time" refers to the shortest time required from the start of warm-up until entering the initial burst period. The time required to enter the initial burst period (hereinafter referred to as "entry time") may vary depending on the temperature of the fixing member 51 at the start of warm-up. Therefore, the shortest time of the rush time is set by the manufacturer of the image forming apparatus 100 within a predetermined temperature range (for example, a range of 0° C. to 140° C.) in which the temperature of the fixing member 51 during warm-up is lower than the initial burst generation start temperature. ), the rush time is measured in advance at the time of shipment. The shortest time among the measured rush times is determined as the "initial burst generation start time."

If the control unit 11 determines in step S604 that t1 has reached the initial burst generation start time, it controls the switching mechanism unit 330 (actuator 88) so that the door unit 86 is placed in the second position 86B. (Second separation mode 330B).

The control unit 11 monitors the surface temperature of the fixing member 51 input from the temperature sensor 320, and determines whether the surface temperature of the fixing member 51 has reached a target temperature (here, the target temperature is 210° C.). A judgment is made (S606).

If the control unit 11 determines in step S606 that the surface temperature of the fixing member 51 has reached the target temperature, it ends the warm-up of the fixing member 51. The control unit 11 controls the heating amount of the heater in the fixing member 51 so that the surface temperature of the fixing member 51 is maintained at the target temperature. The control unit 11 starts measuring the print standby time (t2) (S607).

"Print standby time" refers to the duration of time after the end of warm-up during which the device continues to wait for a print instruction without receiving a print instruction.

The control unit 11 determines whether t1 has reached the initial burst generation end time (S608).

The "initial burst generation end time" refers to the longest time required from the start of warm-up to the end of the initial burst period. The time required from the start of warm-up to the end of the initial burst period (hereinafter referred to as "end time") may vary depending on the temperature of the fixing member 51 at the start of warm-up. Therefore, the maximum end time is determined by the manufacturer of the image forming apparatus 100 within a predetermined temperature range (for example, 0° C. to 140° C.) in which the surface temperature of the fixing member 51 at the start of warm-up is lower than the initial burst generation start temperature. The end time is measured in advance at each temperature (range) at the time of shipment. The longest time among the measured end times is determined as the "initial burst generation end time."

If the control unit 11 determines in step S608 that t1 has reached the initial burst generation end time, it controls the switching mechanism unit 330 (actuator 88) so that the door unit 86 is placed at the first position 86A. (First separation mode 330A). The control unit 11 ends the measurement of t1 (step S609).

The control unit 11 determines whether t2 has reached the standby state transition time (S610). If the control unit 11 determines in step S610 that t2 has reached the standby state transition time, the surface temperature of the fixing member 51 is set to a predetermined temperature (here, 120° C.) lower than the target temperature. The amount of heating by the heater in the fixing member 51 is controlled so that the amount of heat is maintained. Thereby, the process shifts to a standby state (S611).

The "standby state transition time" is a waiting time predetermined by the manufacturer of the image forming apparatus 100 in order to reduce power consumption in the fixing device 50 when the own apparatus is in the print instruction waiting state, and includes, for example, It is 30 minutes.

When the control unit 11 receives the print instruction (S612: YES), the control unit 11 moves to step S602 and repeats steps S603 to S611. When the control unit 11 receives the instruction to turn off the power (step S613: YES), the control unit 11 ends the switching process between the first separation mode 330A and the second separation mode 330B.

In this way, the control unit 11 determines the amount of particulate matter generated in the image forming apparatus 100 and controls the switching mechanism unit 330 (actuator 88) based on the determination result, thereby controlling the amount of particulate matter generated. The conditions for centrifugation in the cyclone separator 81 according to the conditions can be selected from the first separation mode 330A and the second separation mode 330B.

In particular, in this embodiment, the centrifugal separation conditions in the cyclone separator 81 are switched to the second separation mode 330B at a timing corresponding to the initial burst period in which UFP rapidly increases, and at other timings, floating toner is separated. Switch to the first separation mode 330A according to the Thereby, during the initial burst period, a large centrifugal force is applied to a large amount of UFP supplied to the cyclone separator 81, and the UFP can be recovered more reliably.

FIG. 8 is a flowchart showing a modified example of the operation of switching processing between the first separation mode and the second separation mode. In the figure, the same step numbers are assigned to the same processes as the switching process shown in FIG. 7. Hereinafter, steps that are different from the switching process shown in FIG. 7 will be mainly explained.

Referring to FIG. 8, in this modification, by monitoring changes in the surface temperature of fixing member 51, it is determined that image forming apparatus 100 has entered an initial burst period in which the amount of UFP generated rapidly increases. Determine whether the state is the same or not.

After executing steps S601 and S602, the control unit 11 starts monitoring the surface temperature (T) of the fixing member 51 using the temperature sensor 320 (S701). The control unit 11 determines whether T is lower than the initial burst start threshold temperature (S702).

The "initial burst start threshold temperature" refers to a temperature corresponding to the lowest temperature among the initial burst generation start temperatures at which the initial burst period begins from the start of warm-up and the amount of UFP generation begins to rise rapidly. The initial burst generation start temperature may vary depending on the temperature of the fixing member 51 at the start of warm-up. Therefore, depending on the manufacturer of the image forming apparatus 100, the surface temperature of the fixing member 51 at the start of warm-up is set at each temperature within a predetermined temperature range (for example, a range of 0° C. to 140° C.) lower than the initial burst generation start temperature. , the initial burst generation start temperature is measured in advance at the time of shipment. The lowest temperature among the measured initial burst generation start temperatures is determined as the initial burst start threshold temperature.

If the control unit 11 determines in step S702 that T is lower than the initial burst start threshold temperature, it executes switching processing between a first separation mode 330A and a second separation mode 330B, which will be described later (S703). After that, the control unit 11 moves to step S613.

When the control unit 11 determines in step S702 that T is not a temperature lower than the initial burst start threshold temperature, the control unit 11 moves to step S613. If the determination result in step S613 is negative (step S613: NO), the control unit 11 moves to step S702.

FIG. 9 is a flowchart showing the operation of the switching process between the first separation mode and the second separation mode in the modification shown in FIG.

Referring to FIG. 9, the control unit 11 determines whether T has reached the initial burst start threshold temperature (S801). When the control unit 11 determines that T has reached the initial burst start threshold temperature in step S801, the control unit 11 controls the switching mechanism unit 330 (actuator 88) so that the door unit 86 is placed in the second position 86B. (second separation mode 330B). The control unit 11 starts measuring the elapsed time (t3) (step S802).

The control unit 11 determines whether t3 has reached the initial burst generation end time (S803). If the control unit 11 determines in step S803 that t3 has reached the initial burst generation end time, it controls the switching mechanism unit 330 (actuator 88) so that the door unit 86 is placed at the first position 86A. (First separation mode 330A). The control unit 11 ends the measurement at t3 (step S804).

As described in this modification, it is also possible to determine whether the image forming apparatus 100 is in the initial burst period by monitoring changes in the surface temperature of the fixing member 51.

To summarize the configuration of the image forming apparatus 100 according to the first embodiment of the present invention described above, the image forming apparatus 100 according to the present embodiment forms a swirling air flow and separates the air from the air by centrifugal separation. By changing the cyclone separator 81 that can separate particulate matter contained in A switching mechanism section 330 that can switch between a second separation mode 330B in which centrifugation efficiency is high; and a switching mechanism section 330 that determines the amount of particulate matter generated in the image forming apparatus 100 and based on the determination result. A control section 11 is provided.

According to the image forming apparatus 100 according to the first embodiment of the present invention configured as described above, the centrifugation conditions are selected in the cyclone separator 81 according to the amount of particulate matter generated in the image forming apparatus 100. By doing so, particulate matter can be reliably collected.

Note that in this embodiment, two types of UFP and floating toner with different particle sizes are assumed as the particulate matter in the present invention, but the particulate matter can be collected by a centrifugal cyclone separator. If so, there are no particular limitations. Furthermore, the present invention can be applied to cases where the purpose is to collect one type of particulate matter. For example, in order to reliably collect floating toner, the first separation mode 330A is switched to the second separation mode at the timing of a jam when a large amount of floating toner (paper jam) occurs, or at the timing when continuous printing continues for a predetermined period of time. A process of switching to 330B may also be performed.

(Embodiment 2)
In this embodiment, various modifications of the switching mechanism section 330 will be described. The image forming apparatus according to the present embodiment has basically the same configuration as the image forming apparatus 100 according to the first embodiment. Hereinafter, descriptions of overlapping configurations will not be repeated.

Referring to FIG. 2, in the first modification, the switching mechanism section 330 includes a first air blower 66.

The control unit 11 determines the amount of particulate matter generated in the image forming apparatus, and controls the switching mechanism unit 330 (first blower device 66) based on the determination result. When switching the centrifugation conditions to the first separation mode 330A, the control unit 11 causes the first fan 67 to rotate at a first rotation speed (rpm) and sets the centrifugation conditions to a higher efficiency than the first separation mode 330A. When switching to the second separation mode 330B, the first blower device 66 is controlled so that the first fan 67 rotates at a second rotation speed (rpm) higher than the first rotation speed (rpm).

In this modification, by controlling the rotational speed of the first fan 67, the flow rate of air supplied from the first blower device 66 toward the cyclone separator 81 is made variable, thereby improving centrifugal separation in the cyclone separator 81. Conditions can be switched between a first separation mode 330A and a second separation mode 330B.

FIG. 10 is a side view showing a cyclone separator (first separation mode) including a switching mechanism section in a second modification. FIG. 11 is a side view showing the cyclone separator in the arrow direction on the line XI-XI in FIG. 10. FIG. 12 is a side view showing a cyclone separator (second separation mode) including a switching mechanism section in a second modification. FIG. 13 is a side view showing the cyclone separator in the arrow direction on the line XIII-XIII in FIG. 12.

Referring to FIGS. 10 to 13, in this modification, the cyclone separator 81 further includes a second intake part 96.

The second intake section 96 is connected to the cyclone main body section 84. The second intake section 96 is connected to the outer peripheral surface of the cyclone main body section 84. The second intake section 96 is connected to the cyclone main body section 84 at a position offset from the first intake section 82 in the circumferential direction of the predetermined central axis 101 . The second intake section 96 is connected to the cyclone main body section 84 at a position on the opposite side of the first intake section 82 with the predetermined central axis 101 in between, when viewed from above.

The opening area of the second intake section 96 is smaller than the opening area of the first intake section 82 . The size relationship between the opening areas of the first intake section 82 and the second intake section 96 is not particularly limited.

The switching mechanism section 330 includes a second air blower 97. The second blower device 97 is, for example, a propeller fan. The second blower 97 has a second fan 98 . When the second blower device 97 is driven, outside air is introduced into the internal space 91 of the cyclone body 84 through the second air intake section 96 as the second fan 98 rotates.

The control unit 11 determines the amount of particulate matter generated in the image forming apparatus, and controls the switching mechanism unit 330 (second blower device 97) based on the determination result. As shown in FIGS. 10 and 11, the control unit 11 controls the second blower device 97 so that the second fan 98 stops when switching the centrifugal separation conditions to the first separation mode 330A. As shown in FIGS. 12 and 13, the control unit 11 controls the second blower device 97 so that the second fan 98 rotates when switching the centrifugal separation conditions to the second separation mode 330B.

In this modification, the total flow rate of air supplied from the first blower 66 and the second blower 97 toward the cyclone separator 81 is controlled by controlling the stoppage and rotation of the second fan 98 in the second blower 97. By making it variable, the conditions for centrifugation in the cyclone separator 81 can be switched between the first separation mode 330A and the second separation mode 330B.

According to the image forming apparatus according to the second embodiment of the present invention configured as described above, the same effects as described in the first embodiment can be achieved.

(Embodiment 3)
In this embodiment, a modification of the cooling structure of the fixing device 50 will be described. The image forming apparatus according to the present embodiment has basically the same configuration as the image forming apparatus 100 according to the first embodiment. Hereinafter, descriptions of overlapping configurations will not be repeated.

FIG. 14 is a sectional view showing a modification of the cooling structure of the fixing device. FIG. 14 corresponds to FIG. 2 in the first embodiment. FIG. 15 is a perspective view schematically showing an image forming apparatus including a cooling structure for the fixing device shown in FIG.

Referring to FIGS. 14 and 15, in this modification, the image forming apparatus includes a first duct 71 and a second duct 76 instead of the duct 210 in FIG. Each of the first duct 71 and the second duct 76 extends in the front-rear direction (Z-axis direction) of the image forming apparatus. The first duct 71 and the second duct 76 are stacked on each other in the vertical direction (Y-axis direction). The second duct 76 is provided on the first duct 71.

The first duct 71 is arranged inside the exterior body 61 (in-machine space 63). The first duct 71 is connected to the fixing device 50 (case body 56). The second duct 76 is arranged outside the exterior body 61. The second duct 76 is arranged on the top surface 62 of the exterior body 61. The first duct 71 is arranged between the second duct 76 and the fixing device 50 in the vertical direction (Y-axis direction).

A first air blower 66 is arranged in the first duct 71 . A cyclone separator 81 is arranged in the second duct 76 .

The first duct 71 and the second duct 76 form an air flow path 90. Air for cooling the fixing device 50 circulates in the air flow path 90 . The air flow path 90 is an air circulation path that circulates around the fixing device 50 as its starting and ending points. The air flow path 90 is not open to the space outside the exterior body 61.

As the first blower device 66 is driven, an air flow that repeatedly circulates around the air flow path 90 is formed. The air receives heat from the fixing device 50 while flowing along the fixing device 50 in the air flow path 90 . The air, which has become high in temperature due to heat received from the fixing device 50, flows through the air flow path 90 while dissipating heat to the space around the first duct 71 and the second duct 76. The air, which has become low temperature due to heat radiation, is supplied toward the fixing device 50 again.

As shown in this modification, the cyclone separator in the present invention may be provided on the path of the circulating air flow.

According to the image forming apparatus according to the third embodiment of the present invention configured as described above, the same effects as described in the first embodiment can be achieved.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1C, 1K, 1M, 1Y Photosensitive drum, 2C, 2K, 2M, 2Y Charging section, 3C, 3K, 3M, 3Y Optical writing section, 4C, 4K, 4M, 4Y Developing device, 5C, 5K, 5M, 5Y Drum cleaner, 6 Intermediate transfer belt, 7C, 7K, 7M, 7Y Primary transfer roller, 9 Secondary transfer roller, 10, 10C, 10K, 10M, 10Y Image forming section, 11 Control section, 20 Paper feeding device, 21 Feeding Paper tray, 22 Paper feed section, 23, 25 Intermediate conveyance roller, 26 Loop roller, 27 Registration roller, 28 Paper discharge roller, 29 Paper discharge tray, 33 Reversal roller, 41 Main conveyance path, 42 Reverse conveyance path, 43 Refeed paper conveyance path, 50 fixing device, 51, 52 fixing member, 55 switching gate, 56 case body, 57, 62 top surface, 58 loading port, 59 loading port, 61 exterior body, 63 interior space, 66 first blower device, 67 1st fan, 71 1st duct, 76 2nd duct, 81 cyclone separator, 82 1st intake section, 83 exhaust section, 84 cyclone main body section, 85 recovery section, 86 door section, 86A 1st position, 86B 1st position 2 position, 87 shaft section, 88 actuator, 90 air flow path, 91 internal space, 92 peripheral wall section, 93 first opposing wall section, 94 second opposing wall section, 95 intake passage, 96 second intake section, 97 second Air blower, 98 Second fan, 100 Image forming device, 101 Predetermined central axis, 110, 120 Rotating shaft, 210 Duct, 211 Intake port, 212 Exhaust port, 320 Temperature sensor, 330 Switching mechanism section, 330A First separation mode, 330B second separation mode, 401, 402 curve, 502 communication I/F unit, 503 ROM, 504 RAM, 505 image data storage unit, P paper.

Claims (11)

An image forming apparatus,
a cyclone separator that forms a swirling air flow and is capable of separating particulate matter contained in the air from the air by centrifugal separation;
By changing the speed of the air flow in the cyclone separator, the conditions of the centrifugation can be changed between a first separation mode and a second separation mode in which the efficiency of the centrifugation is higher than the first separation mode. A switching mechanism section that can be switched with
An image forming apparatus, comprising: a control section that determines the amount of particulate matter generated in the image forming apparatus, and controls the switching mechanism section based on the determination result. The particulate matter includes a first particulate matter and a second particulate matter having a smaller particle size than the first particulate matter,
The control unit controls the switching mechanism unit to switch the centrifugation conditions to the second separation mode when it is determined that the amount of second particulate matter generated in the image forming apparatus increases. The image forming apparatus according to claim 1. The cyclone separator is
a cyclone main body section defining an internal space for forming the air flow;
an intake section forming an intake passage communicating with the internal space and introducing air containing the particulate matter into the internal space through the intake passage;
The switching mechanism section is
a door portion disposed in the intake passage and capable of opening/closing operations;
an actuator that is connected to the door and opens and closes the door;
When switching the centrifugation conditions to the first separation mode, the control unit is configured such that when switching the centrifugation conditions to the first separation mode, the door portion is arranged in a first position where the intake passage opens with a first area, and the centrifugation conditions are changed to the first separation mode. 2. The actuator is controlled so that, when switching to the second separation mode, the door portion is placed in a second position in which the intake passage opens with a second area smaller than the first area. or the image forming apparatus according to 2. The cyclone main body includes a peripheral wall extending around a predetermined central axis and surrounding the internal space,
The intake part extends in a tangential direction of the peripheral wall part centered on the predetermined central axis, and includes a first opposing wall part continuous to the peripheral wall part, and a first opposing wall part facing the first opposing wall part with the intake passage in between. two opposing wall portions;
The door section is provided so that the intake passage opens between the first opposing wall section and the door section, regardless of whether the door section is placed in the first position or the second position. The image forming apparatus according to claim 3. The switching mechanism includes a first fan, and includes a first blower that introduces air into the cyclone separator as the first fan rotates,
When switching the centrifugation conditions to the first separation mode, the control unit rotates the first fan at a first rotation speed (rpm) and switches the centrifugation conditions to the second separation mode. 3. The first fan according to claim 1 or 2, wherein the first fan is controlled to rotate at a second rotation speed (rpm) higher than the first rotation speed (rpm). Image forming device. The cyclone separator is
a cyclone main body section defining an internal space for forming the air flow;
a first intake part connected to the cyclone main body and for introducing air containing the particulate matter into the internal space;
a second intake part connected to the cyclone main body,
The switching mechanism section includes a second fan, and a second blower device that introduces air into the internal space through the second intake section as the second fan rotates.
The control unit is configured to cause the second fan to stop when switching the centrifugation conditions to the first separation mode, and to stop the second fan when switching the centrifugation conditions to the second separation mode. The image forming apparatus according to claim 1 or 2, wherein the second air blower is controlled to rotate. a fixing device;
further comprising a duct through which air flows to cool the fixing device,
The image forming apparatus according to claim 1 , wherein the cyclone separator is provided in the duct and is disposed on the downstream side of the air flow in the duct with respect to the fixing device. The image forming apparatus according to claim 7, wherein the duct forms a circulation path through which air circulates. The particulate matter includes floating toner and ultra fine particles (UFP) generated in the fixing device,
The fixing device includes a fixing member, and fixes the toner image on the recording medium by heating the fixing member to a target temperature and then pressing the fixing member against the recording medium on which the toner image is formed;
The control unit determines whether or not the image forming apparatus is in an initial burst period in which the amount of ultrafine particles generated from the fixing member rapidly increases, and when it is determined that the image forming apparatus is in the initial burst period. 8. The image forming apparatus according to claim 7, wherein the switching mechanism section is controlled to switch the centrifugation conditions to the second separation mode. The control unit is configured to control the control unit, when the elapsed time from when the power of the image forming apparatus is turned on or from the time when the temperature of the fixing member returns from a standby state where the temperature is lower than the target temperature is within a predetermined range of time. The image forming apparatus according to claim 9, wherein the image forming apparatus determines that the image forming apparatus is in the initial burst period. further comprising a temperature detection unit that detects the temperature of the fixing member,
The control unit may control the temperature detection unit to increase the temperature of the fixing member detected by the temperature detection unit within a predetermined time after reaching a threshold temperature corresponding to a temperature at which the amount of the ultrafine particles starts to increase rapidly. The image forming apparatus according to claim 9, wherein the image forming apparatus determines that the image forming apparatus is in the initial burst period.

Images