Image forming apparatus

Abstract

An image forming apparatus includes: a main body housing having an opening; a cover for opening and closing the opening; a processing unit including a photosensitive drum rotating about an axis and a developer for supplying toner to the photosensitive drum to form a toner image on a sheet; a fuser disposed between the cover and the processing unit in the direction of the photosensitive drum axis for heating and fixing the sheet on which the toner image has been formed; a first exhaust fan for discharging air from the main body housing and disposed above the fuser in the direction of the axis; a second exhaust fan for discharging air from the main body housing and disposed below the fuser in the direction of the axis; and a control unit capable of performing a printing operation to form an image on the sheet. When the printing operation is performed with the cover closed, the control unit sets the drive speed of the second exhaust fan to a first speed or higher, and when the printing operation is performed with the cover open, the control unit sets the drive speed of the second exhaust fan to a second speed lower than the first speed.

Description

Technical Field

[0001] This invention relates to an image forming apparatus. Background Technology

[0002] Previously, as disclosed in Patent Document 1, an image forming apparatus was known, comprising: a body housing with an opening, a cover for opening and closing the opening, a processing unit for forming a toner image on a sheet, a fixing unit for fixing the toner image formed on the sheet, and an exhaust fan for discharging air from the body housing, wherein printing is performed with the cover open.

[0003] In the image forming apparatus described in Patent Document 1, printing is performed with the cover located behind the fuser open, thus opening an opening. However, when printing is performed with the cover behind the fuser open, the airflow generated by the exhaust fan changes compared to printing with the cover closed. Specifically, when the cover is opened, air is drawn into the main housing through the opening, causing heated air from the fuser to flow into the main housing, resulting in adverse conditions such as a temperature rise in the processing section.

[0004] Therefore, in the image forming apparatus described in Patent Document 1, when printing is performed with the cover open, the exhaust fan is driven at a lower speed compared to when the cover is closed, reducing the flow of air into the main body housing, thereby suppressing the temperature rise of the processing unit.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-186495 Summary of the Invention

[0006] However, in an image forming apparatus with multiple exhaust fans, one of which is located below the fuser, when printing with the cover open, heated air may flow below the fuser due to the exhaust fan located below, and flow into the body housing, causing the temperature inside the body housing to rise.

[0007] Therefore, in this invention, an image forming apparatus is provided that suppresses the temperature rise inside the main body housing when printing is performed with the cover open.

[0008] To solve the above problems, the image forming apparatus of the present invention has the following features.

[0009] That is, the image forming apparatus includes: a body housing having an opening; a cover for opening and closing the opening; a processing unit including a photosensitive drum rotatable about an axis and a developer for supplying toner to the photosensitive drum, for forming a toner image on a sheet; a fuser disposed between the cover and the processing unit, viewed from the axial direction of the photosensitive drum, for heating and fixing the sheet on which the toner image has been formed; a first exhaust fan for expelling air from the body housing and disposed above the fuser, viewed from the axial direction; a second exhaust fan for expelling air from the body housing and disposed below the fuser, viewed from the axial direction; and a control unit capable of performing a printing operation to form an image on the sheet, wherein when the printing operation is performed with the cover closed, the control unit sets the drive speed of the second exhaust fan to a first speed or higher, and when the printing operation is performed with the cover open, the control unit sets the drive speed of the second exhaust fan to a second speed lower than the first speed.

[0010] Therefore, when printing with the cover open, it is possible to prevent heated air from flowing into the part below the fuser inside the main body housing, and to suppress the temperature rise inside the main body housing.

[0011] In the image forming apparatus of the present invention, the second speed is a stop.

[0012] This further prevents the air heated by the fuser from flowing into the part below the fuser inside the main housing.

[0013] The image forming apparatus of the present invention further includes a substrate disposed at a position overlapping with the second exhaust fan when viewed from the axial direction, and the control unit is capable of changing the drive speed of the second exhaust fan within a range between a first speed and a third speed higher than the first speed, depending on the temperature of the substrate.

[0014] This helps to suppress the substrate from heating up.

[0015] In the image forming apparatus of the present invention, when the control unit performs the printing operation with the cover closed, the drive speed of the first exhaust fan is set to a speed that varies according to the temperature inside the main body housing and is between a fourth speed and a fifth speed higher than the fourth speed; when the control unit performs the printing operation with the cover open, the drive speed of the first exhaust fan is set to the fourth speed.

[0016] This prevents heated air from flowing into the main body casing.

[0017] In the image forming apparatus of the present invention, when the control unit performs cooling control to suppress temperature rise within the main body housing, it stops the printing operation on the sheet, sets the drive speed of the second exhaust fan to the third speed when the cover is closed, and sets the drive speed of the second exhaust fan to a speed lower than the third speed when the cover is open.

[0018] Therefore, when performing cooling control, it is possible not only to ensure exhaust from the main body housing, but also to prevent the air heated by the fuser from flowing into the part below the fuser inside the main body housing.

[0019] In the image forming apparatus of the present invention, when the control unit performs the cooling control while the printing operation is performed with the cover open, after a first time has elapsed since the start of the cooling control, the drive speed of the second exhaust fan is set to a speed higher than the second speed.

[0020] Therefore, since the second exhaust fan is driven after the temperature of the fuser drops to a certain level, it is possible to prevent hot air from flowing into the main body housing.

[0021] In the image forming apparatus of the present invention, the control unit performs the cooling control when the temperature inside the main body housing is above a first temperature.

[0022] Therefore, by stopping printing and cooling the processing unit inside the body housing when the temperature inside the body housing is high, it is possible to prevent excessive heating of the processing unit inside the body housing.

[0023] The image forming apparatus of the present invention further includes a substrate disposed at a position overlapping with the second exhaust fan when viewed from the axial direction, the substrate being provided with a sensor for detecting the temperature of the substrate, and the control unit performing the cooling control when the temperature of the substrate is above a second temperature.

[0024] Therefore, by stopping printing and cooling the substrate when its temperature is high, it is possible to suppress excessive heating of the substrate.

[0025] The image forming apparatus of the present invention further includes: an intake fan for drawing air into the main body housing; and a conduit for guiding the air drawn into the main body housing along the axial direction to the processing unit.

[0026] Therefore, by guiding the air drawn in by the intake fan to the processing unit, the processing unit can be cooled.

[0027] According to the present invention, the temperature rise inside the main body shell can be suppressed. Attached Figure Description

[0028] Figure 1This is a central cross-sectional view of an image forming apparatus showing the rear cover in the closed position.

[0029] Figure 2 This is a central cross-sectional view of an image forming apparatus showing the rear cover in the open position.

[0030] Figure 3 This is a perspective view showing the image forming apparatus.

[0031] Figure 4 This is an exploded perspective view showing various fans supported on the right frame.

[0032] Figure 5 This is a side view showing the control board and various fans supported on the right frame.

[0033] Figure 6 This is a side view showing the right side wall of the main body housing.

[0034] Figure 7 This is a side view showing various fans supported on the right frame and the air intake duct formed on the right frame.

[0035] Figure 8 This is a block diagram showing various sensors and fans connected to the control unit.

[0036] Figure 9 It is a graph showing the relationship between the operating state of the image forming apparatus and the driving speed of various fans.

[0037] Figure 10 It is a graph showing the relationship between the variable [1] conditions and the drive speed of the first exhaust fan.

[0038] Figure 11 It is a graph showing the relationship between the variable [2] conditions and the drive speed of the second exhaust fan.

[0039] Figure 12 This is a diagram showing the flow of the second exhaust fan's operation control corresponding to the open and closed states of the rear cover.

[0040] Figure 13 This is a diagram showing the flow of the second exhaust fan's operation control during cooling control.

[0041] Figure 14 It is a graph showing the relationship between the variable [3] conditions and the drive speed of the first exhaust fan. Detailed Implementation

[0042] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

[0043] [Image forming apparatus]

[0044] Figures 1 to 3 The image forming apparatus 1 shown is an embodiment of the image forming apparatus of the present invention, which is a color laser printer that forms multi-color images on a sheet S by means of electrophotography.

[0045] In the following explanation, Figure 1 The left side is defined as the front side of the image forming apparatus 1, and will Figure 1 The right side of the image forming apparatus 1 is defined as the rear side. Figure 1 The front side of the paper in the image is defined as the right side of the image forming apparatus 1. Figure 1 The paper depth side is defined as the left side of the image forming apparatus 1. Additionally, Figure 1 The upper and lower sides are defined as the upper and lower sides of the image forming apparatus 1, respectively.

[0046] The image forming apparatus 1 includes a main body housing 2, a sheet feeding section 3 having a sheet tray 10 for supporting a sheet S and a sheet conveying section 30 for conveying the sheet S, and an image forming section 5 for forming an image on the sheet S conveyed by the sheet feeding section 3.

[0047] The main body housing 2 is formed in a generally rectangular shape to house the sheet supply section 3 and the image forming section 5. A front opening 2A is provided on the front surface of the main body housing 2, and the main body housing 2 is equipped with a front cover 21 that can open and close the front opening 2A.

[0048] The front cover 21 is configured to rotate around the rotation shaft 21a at the lower end. By rotating around the rotation shaft 21a, it can move between the closed position of the front opening 2A and the open position of the front opening 2A.

[0049] A rear opening 2B is provided on the rear surface of the main body housing 2, and the main body housing 2 is equipped with a rear cover 29 capable of opening and closing the rear opening 2B. The rear opening 2B is an example of an opening provided by the main body housing 2. The rear cover 29 is an example of a cover for opening and closing the opening.

[0050] The rear cover 29 is configured to rotate around the rotation shaft 29a at its lower end. By rotating around the rotation shaft 29a, the opening 2B can be closed. Figure 1 The position shown) and the opening position of the opening 2B after opening ( Figure 2 Move between the positions shown.

[0051] A top cover 22 is disposed on the upper surface of the main body housing 2, and the top cover 22 has a discharge plate 221 that tilts downward from the front to the rear.

[0052] The sheet supply unit 3 is located at the lower part of the main body housing 2, and the sheet S supported on the sheet tray 10 is transported to the image forming unit 5 by the sheet conveying unit 30. The sheet tray 10 is configured to slide in the forward and backward direction and can move between a receiving position in the main body housing 2 and a separation position pulled forward from the receiving position.

[0053] The sheet conveying unit 30 includes a feed roller 32, a separation roller 33, a separation pad 33a, a conveying roller pair 34, and a positioning roller pair 35. Within the main body housing 2, a conveying path P is formed for the sheet S to travel from the sheet tray 10 through the image forming unit 5 to the discharge tray 221.

[0054] The sheets S supported on the sheet tray 10 are separated one by one by the feed roller 32, the separation roller 33, and the separation pad 33a, and then conveyed to the transport path P. The feed roller 32 is a roller that conveys the sheets S from the sheet tray 10 to the image forming unit 5. The separation roller 33 and the separation pad 33a constitute a separation device for separating the sheets S supported on the sheet tray 10 one by one.

[0055] The sheet S, conveyed to the conveying path P, is transported toward the image forming unit 5 via the conveying roller pair 34 and the positioning roller pair 35. The positioning roller pair 35 restricts the movement of the head end of the conveyed sheet S, causing it to stop temporarily, and then conveys the sheet S toward the image forming unit 5 at a predetermined time.

[0056] The image forming unit 5 is positioned above the film supply unit 3 and includes four processing cartridges 50 arranged in a front-to-back direction and a photosensitive drum 51 corresponding to each processing cartridge 50. Each processing cartridge 50 contains toners for yellow, magenta, cyan, and black. The processing cartridges 50 are arranged from front to back in the order of yellow, magenta, cyan, and black. Each processing cartridge 50 includes a developing roller 52.

[0057] The processing box 50 is supported on the drawer 59 in a removable manner. By opening the front cover 21, the drawer 59 can be pulled out of the main body housing 2 through the front opening 2A. The drawer 59 is movable between a first position disposed inside the main body housing 2 and a second position at least partially disposed outside the main body housing 2.

[0058] The photosensitive drum 51 is formed into a generally cylindrical shape with its axis running horizontally. The photosensitive drum 51 is supported on the drawer 59 and can rotate about its axis running horizontally. That is, the photosensitive drum 51 rotates about its axis. The horizontal direction is an example of the axial direction.

[0059] The developing roller 52 extends in the left-right direction and is supported by the processing cartridge 50 in a rotatable manner. Toner is an example of a developer. The developing roller 52 of the processing cartridge 50 supplies toner to the photosensitive drum 51. The processing cartridge 50 is an example of a developer that supplies toner to the photosensitive drum.

[0060] The housing 2 includes an exposure device 56 for exposing the surface of the photosensitive drum 51. The exposure device 56 includes a laser diode (not shown), a polarizer, a lens, and a reflector. The exposure device 56 emits a light beam to each photosensitive drum 51, exposing the surface of each photosensitive drum 51.

[0061] The transfer belt 41 is positioned opposite the photosensitive drum 51 below it across the transport path P. The transfer belt 41 is in contact with the photosensitive drum 51. The transfer belt 41 is mounted between the drive roller 42 and the driven roller 43 positioned in front of the drive roller 42. Transfer rollers 44 are respectively positioned opposite each photosensitive drum 51 across the transfer belt 41. In the image forming unit 5, the belt unit 40 is composed of the transfer belt 41, the drive roller 42, the driven roller 43, and the transfer rollers 44.

[0062] The image forming unit 5 includes a charge carrier 54 for charging each photosensitive drum 51. The charge carrier 54 is supported by a drawer 59. The photosensitive drums 51, which are uniformly charged by the charge carrier 54, are selectively exposed by the exposure apparatus 56. Through exposure, the charge is selectively removed from the surface of the photosensitive drum 51, and an electrostatic latent image is formed on the surface of the photosensitive drum 51.

[0063] The toner, positively charged and contained in the processing cartridge 50, is carried on the surface of the developing roller 52. A developing bias voltage is applied to the developing roller 52. When the electrostatic latent image formed on the photosensitive drum 51 is opposite to the developing roller 52, toner is supplied from the developing roller 52 to the electrostatic latent image through the potential difference between the electrostatic latent image and the developing roller 52. Thus, a toner image is formed on the surface of the photosensitive drum 51.

[0064] When the sheet S, which is being fed to the image forming unit 5, arrives at the transfer belt 41, it is conveyed by the transfer belt 41 and passes sequentially between the transfer belt 41 and each photosensitive drum 51. When the toner image carried on the surface of the photosensitive drum 51 is opposite to the sheet S, the toner image is transferred onto the sheet S by applying a transfer bias to the transfer roller 44.

[0065] In this embodiment, the transfer belt 41 is configured as a conveyor belt for transporting the sheet S on which the toner image has been transferred. However, it may also be configured as an intermediate transfer belt that transfers the toner image onto the belt itself and then further transfers the toner image transferred onto the belt onto the sheet S.

[0066] A sheet S with a toner image transferred onto it is fed to a fuser 60. The fuser 60 has a heating roller 61 and a pressure roller 62 pressed against the heating roller 61. During the passage of the sheet S fed to the fuser 60 between the heating roller 61 and the pressure roller 62, the toner image is heat-fixed. That is, the fuser 60 heats and fixes the sheet S with the toner image.

[0067] The sheet S containing the toner image, which has been heat-fixed, is transported from the fixer 60 to the downstream side in the transport direction. For example... Figure 1 As shown, when the rear cover 29 is in the closed position, the sheet S conveyed from the fuser 60 to the downstream side of the conveying direction is conveyed by the intermediate discharge roller pair 63 and the discharge roller pair 64 arranged on the downstream side of the conveying direction of the intermediate discharge roller pair 63, and discharged onto the discharge tray 221.

[0068] In addition, such as Figure 2 As shown, when the rear cover 29 is in the open position, the sheet S conveyed from the fuser 60 to the downstream side in the conveying direction is discharged towards the rear of the main body housing 2 through the rear opening 2B. The sheet S discharged from the main body housing 2 towards the rear can be placed on the upper surface of the rear cover 29 when it is in the open position. That is, the sheet S discharged from the main body housing 2 towards the rear can be supported on the optional tray 29b provided by the rear cover 29.

[0069] In the image forming apparatus 1, a processing unit PU is constituted by a drawer 59, a processing box 50 supported by the drawer 59, a photosensitive drum 51, and a belt capacitor 54 for forming a toner image on a sheet S. The processing unit PU is an example of a processing section for forming a toner image on a sheet. Viewed from the left and right, the fuser 60 is disposed between the rear cover 29 and the processing unit PU.

[0070] The processing unit PU only needs to have at least a photosensitive drum 51 and a processing cartridge 50, and may also include a transfer belt 41 or a fuser 60. In the processing unit PU, the photosensitive drum 51 may be supported by a drawer 59 as in this embodiment, or the photosensitive drum 51 may be supported by the processing cartridge 50.

[0071] The image forming apparatus 1 includes a power supply substrate 11 on which power supply circuitry is formed and a substrate cover 12 covering the power supply substrate 11. The substrate cover 12 is disposed at the rear of the body housing 2 between the sheet tray 10 and the tape unit 40. The substrate cover 12 is located below the fuser 60. The body housing 2 houses the processing unit PU and the substrate cover 12.

[0072] [Left frame and right frame]

[0073] like Figure 3 As shown, the main body housing 2 houses a left frame 25 and a right frame 26. The left frame 25 and the right frame 26 are arranged with a gap in the left-right direction. The left frame 25 is located at the left end of the main body housing 2 and extends in the front-back direction and the vertical direction. The right frame 26 is located at the right end of the main body housing 2 and extends in the front-back direction and the vertical direction.

[0074] [First exhaust fan and second exhaust fan]

[0075] like Figures 1 to 5As shown, the image forming apparatus 1 includes a first exhaust fan 71 and a second exhaust fan 72 that discharge air from inside the body housing 2 to the outside of the body housing 2. The first exhaust fan 71 and the second exhaust fan 72 are examples of exhaust fans used to discharge air from inside the body housing 2.

[0076] The first exhaust fan 71 includes a rotating shaft 711 extending in the left-right direction, blades 712 fixed on the rotating shaft 711, and a housing 713 that supports the rotating shaft 711 in a rotatable manner. It is an axial flow fan that delivers air along the axial direction of the rotating shaft 711. The housing 713 of the first exhaust fan 71 is quadrilateral in shape.

[0077] The first exhaust fan 71 is located to the right and rear of the processing unit PU inside the main housing 2, and exhausts the air that has passed through the processing unit PU and the fuser 60 from inside the main housing 2 to the outside of the main housing 2. Thus, the first exhaust fan 71 can effectively exhaust the air that has passed through the processing unit PU and the fuser 60.

[0078] Viewed from the left and right, the first exhaust fan 71 is positioned between the processing unit PU and the rear cover 29 in the closed position. Furthermore, viewed from the left and right, the first exhaust fan 71 is located above the fuser 60. By positioning the first exhaust fan 71 above the fuser 60, the air heated by the fuser 60 inside the main body housing 2 can be effectively exhausted to the outside of the main body housing 2.

[0079] The second exhaust fan 72 includes a rotating shaft 721 extending in the left-right direction, blades 722 fixed on the rotating shaft 721, and a housing 723 that supports the rotating shaft 721 in a rotatable manner. It is an axial flow fan that delivers air along the axial direction of the rotating shaft 721. The housing 723 of the second exhaust fan 72 is quadrilateral in shape.

[0080] The second exhaust fan 72 is disposed to the right of the substrate cover 12 and the power supply board 11 inside the main housing 2. Viewed from the left and right, the second exhaust fan 72 is positioned overlapping the substrate cover 12 and the power supply board 11. The power supply board 11 is an example of a board positioned overlapping the second exhaust fan when viewed from the axial direction.

[0081] The second exhaust fan 72 is located below the first exhaust fan 71. The second exhaust fan 72 is configured to exhaust air inside the substrate cover 12 inside the main body housing 2 to the outside of the main body housing 2.

[0082] Viewed from the left and right, the second exhaust fan 72 is disposed between the processing unit PU and the rear cover 29 in the closed position. Viewed from the left and right, the second exhaust fan 72 is located below the fuser 60. By distributing the second exhaust fan 72 below the fuser 60 and overlapping with the power supply board 11, the heat generated in the power supply board 11 can be effectively exhausted to the outside of the main body housing 2 through the second exhaust fan 72.

[0083] [Support for the first and second exhaust fans]

[0084] like Figures 3 to 6 As shown, the main body housing 2 has a right side wall 23 covering the right side of the right frame 26. The right side wall 23 has a first opening 23a and a second opening 23b that penetrate the right side wall 23 in the left-right direction. The first opening 23a and the second opening 23b are located at the rear of the right side wall 23, with the first opening 23a located above the second opening 23b.

[0085] The right frame 26 has a first fan duct 27 that extends in the left-right direction. The first fan duct 27 extends in the left-right direction, allowing air to circulate in the left-right direction. The first fan duct 27 is formed into a quadrilateral shape when viewed from the left-right direction. A first exhaust fan 71 is embedded in the first fan duct 27 and supported by the right frame 26.

[0086] The first exhaust fan 71 is positioned to overlap with the first opening 23a when viewed from the left-right direction. By driving the first exhaust fan 71, an airflow is generated from left to right. Through the airflow generated by the first exhaust fan 71, air inside the processing unit PU and air near the fuser 60 are discharged to the outside of the main body housing 2 through the first opening 23a. The right side wall 23 is positioned downstream of the first exhaust fan 71 in the exhaust direction of the first exhaust fan 71.

[0087] The right frame 26 has a second fan duct 28 that extends in the left-right direction. The second fan duct 28 is located below the first fan duct 27. The second fan duct 28 extends in the left-right direction, allowing air to circulate in the left-right direction. The second fan duct 28 is formed into a quadrilateral shape when viewed from the left-right direction. The second exhaust fan 72 is embedded in the second fan duct 28 and is supported by the right frame 26.

[0088] Viewed from the left and right, the second exhaust fan 72 is positioned overlapping with the second opening 23b. By driving the second exhaust fan 72, an airflow is generated from left to right. Through the airflow generated by the second exhaust fan 72, air inside the substrate cover 12 is discharged to the outside of the main body housing 2 through the second opening 23b. The right side wall 23 is positioned downstream of the second exhaust fan 72 in the exhaust direction of the second exhaust fan 72.

[0089] [The first louver of the first exhaust fan and the first ozone filter]

[0090] The right side wall 23 of the main body housing 2 has a first louver 24A covering the first opening 23a. The first louver 24A connects the interior and exterior of the main body housing 2. In this embodiment, the first louver 24A is integrally formed with the right side wall 23; however, it is also possible for the first louver 24A to be detachably mounted on the right side wall 23.

[0091] The first louver 24A is located to the right of the first fan duct 27 and the first exhaust fan 71. That is, the first fan duct 27 and the first exhaust fan 71 are arranged in the left-right direction at a position closer to the inside of the main body housing 2 than the first louver 24A.

[0092] Driven by the first exhaust fan 71, the air flowing from left to right has its exhaust direction changed by passing through the first louver 24A. In this embodiment, the exhaust direction of the air flowing from left to right is changed by the first louver 24A to be diagonally upward to the right.

[0093] The image forming apparatus 1 includes a first exhaust filter 73 located in the left-right direction between a first louver 24A and a first exhaust fan 71. The first exhaust filter 73 is supported on the right side wall 23. The first exhaust filter 73 is, for example, a honeycomb filter in which the filter material is formed in a honeycomb pattern.

[0094] The filter material constituting the first exhaust filter 73 can be, for example, paper, aluminum, or other metals or ceramics that carry ozone decomposition catalysts such as manganese dioxide or activated carbon. The first exhaust filter 73 is formed in the shape of a rectangular sheet.

[0095] Inside the main housing 2, components such as the electrical charge 54 of the processing unit PU that discharge in the atmosphere can generate ozone. Additionally, toner contained in the processing box 50 may sometimes float within the main housing 2.

[0096] Air inside the processing unit PU is drawn to the rear of the processing unit PU by the first exhaust fan 71 and then flows to the right, passing through the first exhaust filter 73. Dust such as toner is removed from the air that has passed through the first exhaust filter 73, and the air is discharged to the outside of the main body housing 2 through the first louver 24A. Therefore, it is possible to reduce the amount of dust and other particles contained in the air discharged by the first exhaust fan 71 that has passed through the processing unit PU.

[0097] The air near the fuser 60 contained in the main body housing 2 is easily heated by the heating roller 61 and rises from the vicinity of the fuser 60. After being heated, the air rising from the vicinity of the fuser 60 is drawn upward by the first exhaust fan 71 and flows to the right. After passing through the first exhaust filter 73 to remove dust and the like, it is discharged to the outside of the main body housing 2 through the first louver 24A.

[0098] By using the first exhaust fan 71 to exhaust the air near the fuser 60 to the outside of the main body housing 2, heat near the fuser 60 can be exhausted, thereby reducing the temperature near the fuser 60.

[0099] The first exhaust filter 73 can be any filter capable of removing dust such as toner from the air. In addition to capturing and removing dust such as toner, an ozone filter capable of decomposing ozone in the air can also be used as the first exhaust filter 73.

[0100] [Second louver of the second exhaust fan and second ozone filter]

[0101] The right side wall 23 of the main body housing 2 has a second louver 24B that covers the second opening 23b. The second louver 24B connects the interior and exterior of the main body housing 2. In this embodiment, the second louver 24B is integrally formed with the right side wall 23; however, it is also possible for the second louver 24B to be detachably mounted on the right side wall 23.

[0102] The second louver 24B is located to the right of the second fan duct 28 and the second exhaust fan 72. That is, the second fan duct 28 and the second exhaust fan 72 are arranged in the left-right direction at a position closer to the inside of the main body housing 2 than the second louver 24B.

[0103] Driven by the second exhaust fan 72, the air flowing from left to right has its exhaust direction changed by passing through the second louver 24B. In this embodiment, the exhaust direction of the air flowing from left to right is changed by the second louver 24B to be diagonally upward to the right.

[0104] The image forming apparatus 1 includes a second exhaust filter 74 located in the left-right direction between the second louver 24B and the second exhaust fan 72. The second exhaust filter 74 is supported on the right side wall 23. The second exhaust filter 74 is, for example, a honeycomb filter in which the filter material is formed into a honeycomb shape.

[0105] The filter material constituting the second exhaust filter 74 can be, for example, paper, aluminum, or other metals or ceramics that carry ozone decomposition catalysts such as manganese dioxide or activated carbon. The second exhaust filter 74 is formed in the shape of a rectangular sheet.

[0106] The air inside the substrate cover 12 contained in the main body housing 2 is easily heated by the electronic components mounted on the power supply board 11. The air inside the substrate cover 12 flows from left to right through the second exhaust fan 72, and after ozone and dust are removed by the second exhaust filter 74, it is discharged to the outside of the main body housing 2 through the second louver 24B.

[0107] By using the second exhaust fan 72 to expel the air inside the substrate cover 12 to the outside of the main body housing 2, the temperature of the air inside the substrate cover 12 can be reduced. In addition, the amount of dust and other particles contained in the air inside the main body housing 2 can be reduced.

[0108] The second exhaust filter 74 can be any filter capable of removing dust such as toner from the air. In addition, as the second exhaust filter 74, besides capturing and removing dust such as toner, an ozone filter capable of decomposing ozone in the air can also be used.

[0109] [Intake fan]

[0110] like Figure 3 , Figure 4 and Figure 7 As shown, the right side wall 23 has an air intake 23c that extends through the right side wall 23 in the left-right direction. Air from outside the main body housing 2 can flow into the main body housing 2 through the air intake 23c. The image forming apparatus 1 has an air intake fan 77 disposed inside the right side wall 23 to draw air from outside the main body housing 2 into the main body housing 2. The air intake fan 77 is disposed at the right end and lower front part inside the main body housing 2.

[0111] By driving the intake fan 77, air from outside the main body housing 2 is drawn into the interior of the main body housing 2 through the intake port 23c. The air drawn into the main body housing 2 cools the interior of the main body housing 2, thus suppressing temperature rise inside the main body housing 2.

[0112] The intake fan 77 is supported on the right side of the right frame 26. The intake fan 77 is, for example, a centrifugal fan that draws in air along the rotation axis and discharges it in a centrifugal direction orthogonal to the rotation axis. The intake fan 77 is positioned inside the main body housing 2 with the rotation axis in the left-right direction, and draws air from outside the main body housing 2 into the interior of the main body housing 2 through the intake port 23c.

[0113] The intake fan 77 has an intake section 77a for drawing in air and an exhaust section 77b for discharging air. The intake section 77a is opposite to the intake port 23c on the right side wall 23. The exhaust section 77b is located at the upper end of the intake fan 77 and exhausts air upwards.

[0114] An air intake duct 264 is formed on the right side of the right frame 26. The air intake duct 264 is an intake passage for guiding the air drawn in by the intake fan 77 to the processing unit PU. The air intake duct 264 extends upward from the exhaust section 77b of the intake fan 77 and then extends rearward.

[0115] In the portion of the right frame 26 where the air intake duct 264 is formed, an air intake hole 264a is formed that extends through in the left-right direction. The air intake holes 264a are formed at four positions corresponding to the processing box 50 and the photosensitive drum 51 arranged in the front-back direction.

[0116] Air drawn in from the outside of the main body housing 2 by the intake fan 77 is guided along the right side of the right frame 26 by the intake pipe 264 and flows out to the left through the intake port 264a. The air flowing out to the left from the intake port 264a reaches the processing unit PU, which is located inside the main body housing 2, further than the right frame 26.

[0117] In this way, the suction duct 264 guides the air drawn in by the suction fan 77 towards the processing unit PU in a left-right direction. By guiding the air drawn in by the suction fan 77 towards the processing unit PU, the processing unit PU can be cooled. The suction duct 264 is an example of a duct that guides air drawn into the main housing along the axial direction to the processing section. In addition, by guiding the air drawn in by the suction fan 77 towards the processing unit PU, air can be supplied to the electrical appliance 54 to which a high voltage is applied.

[0118] [Control board and control unit]

[0119] like Figure 5 As shown, a control board 90 is supported on the right side of the right frame 26. The control board 90 constitutes a control unit 9 that controls the operation of the image forming apparatus 1. The control unit 9 includes a CPU, RAM, ROM, input / output circuits, etc. The control unit 9 can control the operation of the sheet supply unit 3, image forming unit 5, fuser 60, etc. of the image forming apparatus 1 by performing various calculations based on programs and data stored in the ROM, etc.

[0120] Furthermore, the control unit 9 can perform the printing operation of forming an image on the sheet S in the image forming apparatus 1. Moreover, the control unit 9 can control the operation of the first exhaust fan 71, the second exhaust fan 72, and the intake fan 77.

[0121] [sensor]

[0122] like Figure 1 and Figure 8As shown, the image forming apparatus 1 includes an external air temperature sensor 91, a body housing internal temperature sensor 92, a substrate temperature sensor 93, and an on / off sensor 95. The external air temperature sensor 91, the body housing internal temperature sensor 92, the substrate temperature sensor 93, and the on / off sensor 95 are connected to the control unit 9. The substrate temperature sensor 93 is an example of a sensor that detects the temperature of the substrate.

[0123] The external temperature sensor 91 is a sensor that detects the temperature outside the main housing 2. For example, the external temperature sensor 91 is supported at the lower front part of the right frame 26 inside the main housing 2, and detects the temperature of the air outside the main housing 2 taken in from the air intake 23c on the right side wall 23. For example, a thermistor can be used as the external temperature sensor 91. The control unit 9 uses the temperature detected by the external temperature sensor 91 as the external temperature Tout.

[0124] The internal temperature sensor 92 is a sensor that detects the temperature inside the body housing 2. For example, the internal temperature sensor 92 is disposed within the body housing 2 between the processing box 50 and the fuser 60, located at the downstream end of the sheet transport direction S. A thermistor can be used, for example, as the internal temperature sensor 92. The control unit 9 calculates the internal temperature Tin of the body housing, for example, using the temperature detected by the external air temperature sensor 91, the temperature detected by the internal temperature sensor 92, and the operating states of the processing unit PU and the fuser 60.

[0125] The internal temperature Tin of the main body housing is the temperature used when controlling the cooling of the internal temperature of the main body housing 2, such as the processing unit PU. The internal temperature Tin can also be the temperature detected by the internal temperature sensor 92 of the main body housing.

[0126] The substrate temperature sensor 93 is a sensor that detects the temperature of the power supply board 11. The substrate temperature sensor 93 is mounted on the power supply board 11, for example. A thermistor can be used as the substrate temperature sensor 93, for example. The control unit 9 uses the temperature detected by the substrate temperature sensor 93 as the substrate temperature Tcb, for example.

[0127] The opening / closing sensor 95 is a sensor that detects the rear cover 29. The opening / closing sensor 95 is disposed at the rear end and upper end of the main housing 2, and detects the rear cover 29 when it is in the closed position. When the rear cover 29 is in the open position, the opening / closing sensor 95 does not detect the rear cover 29. The control unit 9 determines that the rear cover 29 is in the closed position when the opening / closing sensor 95 detects the rear cover 29, and determines that the rear cover 29 is in the open position when the opening / closing sensor 95 does not detect the rear cover 29.

[0128] [Explanation of fan operation]

[0129] The first exhaust fan 71, the second exhaust fan 72, and the intake fan 77 are connected to the control unit 9. The control unit 9 can control the operation of the first exhaust fan 71, the second exhaust fan 72, and the intake fan 77 based on the external air temperature Tout, the internal temperature Tin of the main body housing, the substrate temperature Tcb, and the open and closed state of the rear cover 29.

[0130] The control unit 9 can control the operation of the first exhaust fan 71 to set its drive speed to, for example, high speed V1A, low speed V1C, or stop V1D. High speed V1A is a drive speed higher than low speed V1C. Stop V1D is a state where the drive speed is 0, which is a drive speed lower than both high speed V1A and low speed V1C.

[0131] Low speed V1C is an example of the fourth speed, and high speed V1A is an example of the fifth speed, which is higher than the fourth speed. Stopping V1D is an example of the sixth speed.

[0132] In this way, the control unit 9 can stop the drive of the first exhaust fan 71 when it is driven at high speed V1A or low speed V1C, so that the drive speed of the first exhaust fan 71 becomes the stop V1D.

[0133] The control unit 9 can control the operation of the second exhaust fan 72, setting its drive speed to, for example, high speed V2A, medium speed V2B, low speed V2C, and stop V2D. High speed V2A is a drive speed higher than low speed V2C and medium speed V2B. Medium speed V2B is a drive speed higher than low speed V2C. Stop V2D is a state where the drive speed is 0, which is a drive speed lower than high speed V2A, medium speed V2B, and low speed V2C.

[0134] Low-speed V2C is an example of the first speed; stationary V2D is an example of the second speed, which is lower than the first speed; high-speed V2A is an example of the third speed, which is higher than the first speed; and medium-speed V2B is an example of the seventh speed.

[0135] In this way, the control unit 9 can stop the second exhaust fan 72 when it is driven at high speed V2A, medium speed V2B or low speed V2C, so that the driving speed of the second exhaust fan 72 becomes the stop V2D.

[0136] The control unit 9 controls the operation of the intake fan 77, setting its drive speed to, for example, high speed V3A or stop V3D. High speed V3A is a drive speed higher than stop V3D. Stop V3D is a drive speed of 0, which is a drive speed lower than high speed V3A. High speed V3A is an example of the eighth speed, and stop V3D is an example of the ninth speed.

[0137] In this way, the control unit 9 can stop the drive of the intake fan 77 when it is driven at high speed V3A, so that the drive speed of the intake fan 77 becomes the stop V3D.

[0138] The high-speed V1A, low-speed V1C, and stop V1D of the first exhaust fan 71 represent the relative magnitudes of its drive speed. The high-speed V2A, medium-speed V2B, low-speed V2C, and stop V2D of the second exhaust fan 72 represent the relative magnitudes of its drive speed. The high-speed V3A and stop V3D of the intake fan 77 represent the relative magnitudes of its drive speed.

[0139] Therefore, the absolute magnitudes of the driving speeds of the high-speed V1A of the first exhaust fan 71, the high-speed V2A of the second exhaust fan 72, and the high-speed V3A of the intake fan 77 may not be the same. That is, high-speed V1A, high-speed V2A, and high-speed V3A can be the same or different. Furthermore, the absolute magnitudes of the driving speeds of the low-speed V1C of the first exhaust fan 71 and the low-speed V2C of the second exhaust fan 72 may not be the same. That is, low-speed V1C and low-speed V2C can be the same or different.

[0140] [Control of the first exhaust fan's operation during printing]

[0141] When performing the printing operation, the control unit 9 controls the operation of the first exhaust fan 71 as follows.

[0142] like Figure 9 , Figure 10 As shown, during the execution of the printing operation, when the control unit 9 determines that the rear cover 29 is in the closed position, it controls the operation of the first exhaust fan 71 so that the drive speed varies according to the temperature Tin inside the main body housing. Figure 10 (Variable conditions in [1]). When the control unit 9 performs the printing operation, the fuser 60 is heated to the fuser temperature.

[0143] Specifically, when the temperature Tin inside the main body housing is high (Tin1), the control unit 9 sets the drive speed of the first exhaust fan 71 to high speed (V1A). Furthermore, when the temperature Tin inside the main body housing is medium (Tin2), the control unit 9 sets the drive speed of the first exhaust fan 71 to low speed (V1C). Moreover, when the temperature Tin inside the main body housing is low (Tin3), the control unit 9 sets the drive speed of the first exhaust fan 71 to low speed (V1C).

[0144] Here, high temperature Tin1 is a temperature higher than medium temperature Tin2, and medium temperature Tin2 is a temperature higher than low temperature Tin3.

[0145] When the temperature Tin inside the main body housing is high temperature Tin1, which is higher than the medium temperature Tin2 and the low temperature Tin3, the temperature inside the main body housing 2, such as the processing unit PU, can be effectively cooled by setting the drive speed of the first exhaust fan 71 to high speed V1A, which is higher than the low speed V1C.

[0146] In this embodiment, when the temperature Tin inside the main body housing is high at Tin1, the control unit 9 sets the drive speed of the first exhaust fan 71 to high speed V1A, but is not limited to this. That is, when the temperature Tin inside the main body housing is high at Tin1, the control unit 9 can set the drive speed of the first exhaust fan 71 to a speed higher than low speed V1C, which is between high speed V1A and low speed V1C.

[0147] Furthermore, when the temperature Tin inside the main body housing is at a medium temperature Tin2, the control unit 9 sets the drive speed of the first exhaust fan 71 to a low speed V1C, but is not limited to this. That is, when the temperature Tin inside the main body housing is at a medium temperature Tin2, the control unit 9 can set the drive speed of the first exhaust fan 71 to a speed lower than the drive speed of the first exhaust fan 71 at a high temperature Tin1 and higher than the low speed V1C.

[0148] Furthermore, when the temperature Tin inside the main body housing is low at Tin3, the control unit 9 sets the drive speed of the first exhaust fan 71 to a low speed V1C, but is not limited to this. That is, when the temperature Tin inside the main body housing is low at Tin3, the control unit 9 can set the drive speed of the first exhaust fan 71 to a speed that is lower than or higher than the drive speed of the first exhaust fan 71 at the medium temperature Tin2 and lower than the low speed V1C.

[0149] On the other hand, during the execution of the printing operation, when the control unit 9 determines that the rear cover 29 is in the open position, it controls the operation of the first exhaust fan 71 to make the drive speed low speed V1C.

[0150] With the rear cover 29 in the open position, when the first exhaust fan 71 is driven at a high speed V1A, the airflow into the main body housing 2 from the rear opening 2B increases. In this situation, when the air flowing into the main body housing 2 from the rear opening 2B is heated near the fuser 60 and flows into the processing unit PU that transfers the toner image onto the sheet S, the processing unit PU becomes hot, and the temperature inside the main body housing 2 may rise.

[0151] However, when the rear cover 29 is in the open position, the control unit 9 controls the operation of the first exhaust fan 71, so that the drive speed of the first exhaust fan 71 is low speed V1C. Therefore, the flow rate of heated air into the main body housing 2 is reduced, which can suppress the temperature rise inside the main body housing 2.

[0152] Thus, when the control unit 9 performs the printing operation with the rear cover 29 closed, it sets the drive speed of the first exhaust fan 71 to a speed between a low speed V1C and a high speed V1A, which is higher than the low speed V1C, i.e., a speed that varies according to the temperature Tin inside the body housing. When the printing operation is performed with the rear cover 29 open, the drive speed of the first exhaust fan 71 is set to the low speed V1C. This suppresses the flow of heated air inside the body housing 2.

[0153] [Control of the second exhaust fan during printing]

[0154] When performing the printing operation, the control unit 9 controls the operation of the second exhaust fan 72 as follows.

[0155] like Figure 9 , Figure 11 As shown, during the execution of the printing operation, when the control unit 9 determines that the rear cover 29 is in the closed position, it controls the operation of the second exhaust fan 72 so that the drive speed varies according to the substrate temperature Tcb, the internal temperature Tin of the body housing, and the external air temperature Tout. Figure 11 The variable [2] conditions in the middle).

[0156] In this situation, the control unit 9 controls the operation of the second exhaust fan 72 to set its drive speed to a low speed V2C or higher. That is, when the control unit 9 performs the printing operation with the rear cover 29 closed, it sets the drive speed of the second exhaust fan 72 to a low speed V2C or higher. Furthermore, the control unit 9 varies the drive speed of the second exhaust fan 72 within a range between low speed V2C and high speed V2A. During the printing operation, the fuser 60 is heated to its fuser temperature.

[0157] Specifically, when the substrate temperature Tcb is high (Tcb1), the control unit 9 sets the drive speed of the second exhaust fan 72 to high speed (V2A), regardless of the internal temperature Tin of the main body casing and the external air temperature Tout. Conversely, when the substrate temperature Tcb is low (Tcb3) and the internal temperature Tin of the main body casing is high (Tin1), the control unit 9 sets the drive speed of the second exhaust fan 72 to medium speed (V2B), regardless of the external air temperature Tout.

[0158] Furthermore, when the substrate temperature Tcb is low (Tcb3), the internal temperature Tin of the main body casing is medium (Tin2) or low (Tin3), and the external temperature Tout is high (Tout1), the control unit 9 sets the drive speed of the second exhaust fan 72 to medium speed (V2B). Additionally, when the substrate temperature Tcb is low (Tcb3), the internal temperature Tin of the main body casing is medium (Tin2) or low (Tin3), and the external temperature Tout is low (Tout3), the control unit 9 sets the drive speed of the second exhaust fan 72 to low speed (V2C).

[0159] Here, the high temperature Tcb1 is a higher temperature than the low temperature Tcb3. Additionally, the high temperature Tout1 is a higher temperature than the low temperature Tout3.

[0160] When the substrate temperature Tcb is a high temperature Tcb1, which is higher than the low temperature Tcb3, by setting the drive speed of the second exhaust fan 72 to a high speed V2A, which is higher than the medium speed V2B and the low speed V2C, the heat generated by the power supply substrate 11 can be effectively discharged to the outside of the main body housing 2 through the second exhaust fan 72. This suppresses the temperature rise inside the main body housing 2, including the power supply substrate 11.

[0161] Furthermore, even if the substrate temperature Tcb is a low temperature Tcb3, when the temperature Tin inside the main body housing is a high temperature Tin1, which is higher than the medium temperature Tin2 and the low temperature Tin3, the temperature rise inside the main body housing 2, including the power supply board 11, can be suppressed by setting the drive speed of the second exhaust fan 72 to a medium speed V2B, which is higher than the low speed V2C.

[0162] Furthermore, even if the substrate temperature Tcb is low-temperature Tcb3 and the body housing temperature Tin is medium-temperature Tin2 or low-temperature Tin3, when the external temperature Tout is high-temperature Tout1, by setting the drive speed of the second exhaust fan 72 to medium-speed V2B, which is higher than the low-speed V2C, it is possible to suppress the temperature inside the body housing 2, including the power supply board 11, from rising due to the influence of the external temperature Tout.

[0163] In addition, when the substrate temperature Tcb is low-temperature Tcb3, the body housing temperature Tin is medium-temperature Tin2 or low-temperature Tin3, and the external air temperature Tout is low-temperature Tout3, the power consumption of the image forming apparatus 1 can be suppressed by setting the drive speed of the second exhaust fan 72 to low speed V2C.

[0164] In this way, by configuring the control unit 9 to perform the printing operation with the rear cover 29 closed, the drive speed of the second exhaust fan 72 can be changed within the range between low speed V2C and high speed V2A according to the substrate temperature Tcb, thereby suppressing the temperature rise of the power supply board 11.

[0165] On the other hand, during the execution of the printing operation, when the control unit 9 determines that the rear cover 29 is in the open position, it controls the operation of the second exhaust fan 72 so that the drive speed becomes the stop V2D.

[0166] With the rear cover 29 in the open position, when the second exhaust fan 72 is driven at a low speed V1C or higher, air flows into the main body housing 2 from the rear opening 2B. In this situation, when the air flowing into the main body housing 2 from the rear opening 2B is heated near the fuser 60, and then flows into the portion of the main body housing 2 below the fuser 60, the temperature of the portion of the main body housing 2 below the fuser 60 may rise.

[0167] However, when the control unit 9 performs the printing operation with the rear cover 29 open, it controls the operation of the second exhaust fan 72 to stop its drive, setting the drive speed to stop V2D. This prevents heated air from flowing into the portion below the fuser 60 inside the body housing 2. Consequently, it suppresses the temperature rise inside the body housing 2.

[0168] In this embodiment, when printing is performed with the rear cover 29 open, the operation of the second exhaust fan 72 is controlled to make the drive speed stop V2D, but the second exhaust fan 72 can also be driven at a speed lower than the low speed V2C. Even when the operation of the second exhaust fan 72 is controlled to make the drive speed lower than the low speed V2C, the temperature rise inside the main body housing 2 can be suppressed compared to the case where the operation of the second exhaust fan 72 is controlled to make the drive speed low speed V2C.

[0169] However, by controlling the operation of the second exhaust fan 72 to make the drive speed stop V2D, it is possible to further suppress the flow of air heated by the fuser 60 into the part below the fuser 60 inside the main body housing 2.

[0170] In addition, the control unit 9 can determine the open and closed state of the rear cover 29 when the printing operation starts and during the execution of the printing operation, and control the operation of the second exhaust fan 72 according to the open and closed state of the rear cover 29.

[0171] like Figure 12 As shown, when the printing operation begins, the control unit 9 determines whether the rear cover 29 is in the open or closed position (step S01). In this case, the control unit 9 determines the open or closed state of the rear cover 29 based on whether the open / close sensor 95 detects the rear cover 29.

[0172] When the control unit 9 determines in step S01 that the rear cover 29 is in the open position (step S01: Yes), it controls the operation of the second exhaust fan 72 to make the drive speed stop V2D (step S02).

[0173] On the other hand, when the control unit 9 determines in step S01 that the rear cover 29 is in the closed position (step S01: No), it controls the operation of the second exhaust fan 72 to make the second exhaust fan 72 perform normal operation (step S03). Here, the normal operation of the second exhaust fan 72 refers to the operation in which the drive speed varies between low speed V2C and high speed V2A when printing is performed with the rear cover 29 open, depending on the substrate temperature Tcb, the internal temperature Tin of the body housing, and the external air temperature Tout.

[0174] After controlling the operation of the second exhaust fan 72 in step S02 to make the drive speed reach the stop V2D, the control unit 9 determines whether the printing operation has ended (step S04). Alternatively, after controlling the operation of the second exhaust fan 72 in step S03 to make the second exhaust fan 72 perform normal operation, the control unit 9 determines whether the printing operation has ended (step S04).

[0175] In step S04, the control unit 9 determines that the printing operation has ended (step S04: yes) and controls the operation of the second exhaust fan 72 when the printing operation ends.

[0176] If the control unit 9 determines in step S04 that the printing operation has not ended (step S04: No), it returns to step S01 and determines again whether the rear cover 29 is in the open or closed position.

[0177] After the control unit 9 sets the drive speed of the second exhaust fan 72 to stop V2D in step S02, if it determines again in step S01 that the rear cover 29 is in the open position, it continues to set the drive speed of the second exhaust fan 72 to stop V2D.

[0178] On the other hand, after the control unit 9 sets the operation of the second exhaust fan 72 to normal operation in step S03, if it determines in step S01 that the rear cover 29 is in the open position, it switches the drive speed of the second exhaust fan 72 to stop V2D.

[0179] That is, during the execution of the printing operation, when the rear cover 29 changes from the closed position to the open position, the control unit 9 switches from the normal operation state of the second exhaust fan 72 to a stop speed (V2D) for the second exhaust fan 72. Therefore, even when the rear cover 29 moves from the closed position to the open position during the printing operation, it is possible to prevent heated air from flowing into the portion below the fuser 60 of the main body housing 2.

[0180] [Control of the suction fan during printing]

[0181] When performing a printing operation, the control unit 9 controls the operation of the suction fan 77 as follows.

[0182] like Figure 9 As shown, when the control unit 9 determines that the rear cover 29 is in the closed position during the printing operation, and when it determines that the rear cover 29 is in the open position during the printing operation, it controls the operation of the suction fan 77 to make the drive speed high-speed V3A. This allows the air drawn in by the suction fan 77 to be guided to the processing unit PU, thereby cooling the processing unit PU.

[0183] [Cooling Control]

[0184] The control unit 9 can perform cooling control to stop the printing operation and suppress the temperature rise inside the body housing 2 when the specified conditions are met.

[0185] The starting conditions for cooling control are: when the substrate temperature Tcb is above the cooling start temperature Tcb_on, when the internal temperature Tin of the body housing is above the cooling start temperature Tin_on, or when the external air temperature Tout is above the cooling start temperature Tout_on. The cooling start temperature Tin_on of the internal temperature Tin of the body housing is an example of a first temperature. The cooling start temperature Tcb_on of the substrate temperature Tcb is an example of a second temperature.

[0186] In this case, the cooling start temperature Tcb_on of the substrate temperature Tcb can be set, for example, to a temperature higher than the high temperature Tcb1. Additionally, the cooling start temperature Tin_on of the internal temperature Tin of the body casing can be set, for example, to a temperature higher than the high temperature Tin1. The cooling start temperature Tout_on of the external temperature Tout can be set, for example, to a temperature higher than the high temperature Tout1.

[0187] The cooling start temperature Tcb_on of the substrate temperature Tcb can be set to, for example, 80°C. The cooling start temperature Tin_on of the body housing temperature Tin can be set to, for example, 42°C. The cooling start temperature Tout_on of the external air temperature Tout can be set to, for example, 42.5°C.

[0188] That is, the control unit 9 starts cooling control when at least one of the following conditions is met: Tcb≥Tcb_on, Tin≥Tin_on, and Tout≥Tout_on.

[0189] The control unit 9 performs cooling control when the temperature Tin inside the body housing reaches or exceeds the cooling start temperature Tin_on. Therefore, it can stop printing and perform cooling when the temperature inside the body housing 2 is high. This helps to prevent the processing unit PU inside the body housing 2 from overheating.

[0190] The control unit 9 executes cooling control when the substrate temperature Tcb is equal to or higher than the cooling start temperature Tcb_on, therefore, printing can be stopped for cooling when the temperature of the power supply substrate 11 is high. Accordingly, excessive temperature rise of the power supply substrate 11 can be suppressed.

[0191] The control unit 9 executes cooling control when the external air temperature Tout is equal to or higher than the cooling start temperature Tout_on, therefore, printing can be stopped for cooling when the temperature inside the main body housing 2 is likely to become high due to the influence of the external air temperature Tout. Accordingly, excessive temperature rise inside the main body housing 2 due to the influence of the external air temperature Tout can be suppressed.

[0192] In addition, the control unit 9 can cancel the cooling control when a predetermined condition is satisfied after starting the cooling control.

[0193] The cancellation condition for cooling control is that the substrate temperature Tcb does not reach the cooling cancellation temperature Tcb_off, the temperature inside the main body housing Tin does not reach the cooling cancellation temperature Tin_off, and the external air temperature Tout does not reach the cooling cancellation temperature Tout_off.

[0194] That is, the control unit 9 cancels the cooling control when all of the conditions Tcb<Tcb_off, Tin<Tin_on and Tout<Tout_on are satisfied.

[0195] The cooling cancellation temperature Tcb_off of the substrate temperature Tcb can be set to, for example, 75°C. The cooling cancellation temperature Tin_off of the temperature inside the main body housing Tin can be set to, for example, 41°C. The cooling cancellation temperature Tout_off of the external air temperature Tout can be set to, for example, 41.5°C.

[0196] In the image forming apparatus 1, when switching from a printing operation state to a cooling control execution state, the power supply to the fuser 60 is stopped, and the temperature of the fuser 60 heated to the fixing temperature decreases as time passes.

[0197] [Control of Operation of First Exhaust Fan when Cooling Control is Executed]

[0198] as Figure 9 shows, when the control unit 9 executes cooling control during a printing operation and it is determined that the rear cover 29 is in the closed position, the control unit 9 stops the printing operation on the sheet S and sets the driving speed of the first exhaust fan 71 to a high speed V1A.

[0199] When the rear cover 29 is in the closed state and cooling control is executed, by setting the driving speed of the first exhaust fan 71 to the high speed V1A, the temperature inside the main body housing 2 such as the processing unit PU can be effectively cooled.

[0200] In addition, when the control unit 9 performs cooling control during the printing operation, it stops the printing operation on the sheet S when it determines that the rear cover 29 is in the open position, so that the drive speed of the first exhaust fan 71 becomes a low speed V1C, which is lower than the high speed V1A.

[0201] When the rear cover 29 is open, during cooling control, the flow rate of heated air into the main body housing 2 is reduced by setting the drive speed of the first exhaust fan 71 to a low speed V1C, thereby suppressing the temperature rise inside the main body housing 2.

[0202] In this embodiment, when the control unit 9 performs cooling control with the rear cover 29 open, the drive speed of the first exhaust fan 71 is set to low speed V1C. However, the operation of the first exhaust fan 71 can be controlled to a speed other than low speed V1C, as long as it is lower than high speed V1A. Even in this case, the flow rate of heated air into the main body housing 2 can be reduced, thereby suppressing the temperature rise inside the main body housing 2.

[0203] In this way, when performing cooling control, the control unit 9 stops the printing operation on the sheet S. When the rear cover 29 is closed, the drive speed of the first exhaust fan 71 is set to high speed V1A. When the rear cover 29 is open, the drive speed of the first exhaust fan 71 is set to a speed lower than high speed V1A. Thus, when performing cooling control, it is possible to ensure exhaust from the body housing 2 while preventing heated air from flowing into the body housing 2.

[0204] [Control of the second exhaust fan's operation during cooling control]

[0205] like Figure 9 As shown, when the control unit 9 performs cooling control during the printing operation, it stops the printing operation on the sheet S when it determines that the rear cover 29 is in the closed position, and makes the drive speed of the second exhaust fan 72 high speed V2A.

[0206] With the rear cover 29 closed, when cooling control is performed, the temperature inside the main body housing 2, such as the processing unit PU, can be effectively cooled by setting the drive speed of the second exhaust fan 72 to high speed V2A.

[0207] In addition, when the control unit 9 performs cooling control during the printing operation, it stops the printing operation on the sheet S when it determines that the rear cover 29 is in the open position, so that the drive speed of the second exhaust fan 72 becomes a low speed V2C, which is lower than the high speed V2A.

[0208] With the rear cover 29 in the open state, when cooling control is performed, by setting the drive speed of the second exhaust fan 72 to a low speed V2C, the flow of air heated by the fuser 60 into the part of the main body housing 2 located below the fuser 60 can be suppressed, thereby suppressing the temperature rise inside the main body housing 2.

[0209] In this embodiment, when the control unit 9 performs cooling control with the rear cover 29 open, the drive speed of the second exhaust fan 72 is set to low speed V2C. However, the operation of the second exhaust fan 72 can be controlled to a speed other than low speed V2C, as long as it is lower than high speed V2A. Even in this case, it is possible to prevent the air heated by the fuser 60 from flowing into the part below the fuser 60 inside the main body housing 2, thereby suppressing the temperature rise inside the main body housing 2.

[0210] In this way, when the control unit 9 performs cooling control, it stops the printing operation on the sheet S. When the rear cover 29 is closed, the drive speed of the second exhaust fan 72 is set to high speed V2A. When the rear cover 29 is open, the drive speed of the second exhaust fan 72 is set to a speed lower than high speed V2A. Therefore, when performing cooling control, it is possible to ensure exhaust from the body housing 2 while preventing air heated by the fuser 60 from flowing into the part below the fuser 60 inside the body housing 2.

[0211] Furthermore, during the printing operation with the rear cover 29 in the open position, the control unit 9 sets the drive speed of the second exhaust fan 72 to stop (V2D). Therefore, during the printing operation with the rear cover 29 in the open position, when cooling control is initiated, the control unit 9 switches the drive speed of the second exhaust fan 72 from stop (V2D) to low speed (V2C).

[0212] In this situation, the control unit 9 can switch the drive speed of the second exhaust fan 72 from the stop V2D to the low speed V2C after the first time TM has elapsed since the start of cooling control.

[0213] like Figure 13 As shown, during the execution of the printing operation, the control unit 9 determines whether at least one of the following conditions is met: Tcb≥Tcb_on, Tin≥Tin_on, and Tout≥Tout_on (step S11). If the control unit 9 determines in step S11 that at least one of the following conditions is met (step S11: Yes), cooling control is executed. When the printing operation is performed with the rear cover 29 in the open position, the drive speed of the second exhaust fan 72 is stopped (V2D).

[0214] When the control unit 9 determines in step S11 that none of the conditions Tcb≥Tcb_on, Tin≥Tin_on and Tout≥Tout_on is satisfied (step S11: No), the process ends without executing cooling control. Herein, step S11 is executed at a predetermined interrupt timing during execution of a printing operation.

[0215] When the control unit 9 determines in step S11 that at least one of the conditions Tcb≥Tcb_on, Tin≥Tin_on and Tout≥Tout_on is satisfied (step S11: Yes), it determines whether the rear cover 29 is in an open position (step S12).

[0216] When the control unit 9 determines in step S12 that the rear cover 29 is in the open position (step S12: Yes), it determines whether a count value M stored in the control unit 9 is 0 (step S13). When the control unit 9 performs the determination of whether the rear cover 29 is in the open position for the first time, the count value M is set as M=0.

[0217] If the control unit 9 determines in step S13 that the count value M is 0, i.e., M=0 (step S13: Yes), after waiting for a first time TM (step S14), it executes cooling control when the rear cover 29 is in an open state (step S15). In the cooling control of step S15, the control unit 9 controls the operation of the second exhaust fan 72, such that the driving speed of the second exhaust fan 72 which is in a stopped state V2D becomes a low speed V2C. That is, the driving speed of the second exhaust fan 72 is switched from the stopped state V2D to the low speed V2C.

[0218] On the other hand, when the control unit 9 determines in step S12 that the rear cover 29 is in a closed position (step S12: No), it executes cooling control when the rear cover 29 is in a closed state (step S16). In the cooling control of step S16, the control unit 9 controls the operation of the second exhaust fan 72, such that the driving speed of the second exhaust fan 72 which is in a stopped state V2D becomes a high speed V2A. That is, the driving speed of the second exhaust fan 72 is switched from the stopped state V2D to the high speed V2A.

[0219] After the control unit 9 executes the cooling control in step S15 or the cooling control in step S16, it executes step S17. In step S17, the control unit 9 determines whether all of the conditions Tcb<Tcb_off, Tin<Tin_on and Tout<Tout_on are satisfied.

[0220] In step S17, when the control unit 9 determines that not all of the conditions Tcb<Tcb_off, Tin<Tin_on and Tout<Tout_on are satisfied (step S17: No), it again determines whether the rear cover 29 is in the open position in step S12. When the control unit 9 transfers from step S17 to step S12, it increments the count value M by 1 (M=M+1).

[0221] When the control unit 9 determines in the repeated step S12 that the rear cover 29 is in the open position (step S12: Yes), it determines whether the count value M stored in the control unit 9 is 0 (step S13).

[0222] In this case, since the count value M becomes M=M+1 during the transfer from step S17 to step S12, the control unit 9 determines in step S13 that the count value M is not 0 (step S13: No). After the control unit 9 determines in step S13 that the count value M is not 0, it does not enter standby, and executes cooling control when the rear cover 29 is in the open state (step S15).

[0223] When the control unit 9 determines in step S17 that all of the conditions Tcb<Tcb_off, Tin<Tin_on and Tout<Tout_on are satisfied (step S17: Yes), it cancels the cooling control (step S18).

[0224] In this way, when the control unit 9 performs cooling control during a printing operation with the rear cover 29 in the open state, after a first time TM has elapsed from the start of cooling control, it sets the driving speed of the second exhaust fan 72 to a low speed V2C, which is higher than the stopped speed V2D.

[0225] In the image forming apparatus 1, when transitioning from a printing operation state to a cooling control state with the rear cover 29 open, the power supply to the fuser 60 is stopped, and the first exhaust fan 71 is driven at a driving speed of low speed V1C. Accordingly, the temperature of the fuser 60 decreases from the fixing temperature as time passes.

[0226] Therefore, by changing the driving speed of the second exhaust fan 72 from stopped V2D to low speed V2C after the first time TM has elapsed from the start of cooling control, the second exhaust fan 72 is driven after the temperature of the fuser 60 has decreased to a certain extent. Accordingly, high-temperature air can be suppressed from flowing into the main body casing 2.

[0227] [Control of Operation of Suction Fan During Execution of Cooling Control]

[0228] When the control unit 9 executes cooling control during a printing operation, it stops the printing operation on the sheet S and controls the operation of the suction fan 77 as follows.

[0229] like Figure 9 As shown, when the control unit 9 performs cooling control during the printing operation, it controls the operation of the suction fan 77 to achieve a high-speed drive speed of V3A when it determines that the rear cover 29 is in the closed position and when it determines that the rear cover 29 is in the open position. This allows the air drawn in by the suction fan 77 to be directed to the processing unit PU, thereby cooling the processing unit PU.

[0230] [Control of the first exhaust fan's operation in standby mode]

[0231] The image forming apparatus 1 enters a standby state upon startup or after the printing operation is completed, under the control of the control unit 9. When the image forming apparatus 1 is in standby state, the control unit 9 maintains the temperature of the fuser 60 at a standby temperature that is lower than the fuser temperature.

[0232] When the image forming apparatus 1 is in standby mode, the control unit 9 controls the operation of the first exhaust fan 71 as follows.

[0233] like Figure 9 , Figure 14 As shown, when the image forming apparatus 1 is in standby mode, the control unit 9 controls the operation of the first exhaust fan 71 when it determines that the rear cover 29 is in the closed position, so that the drive speed varies according to the temperature Tin inside the main body housing. Figure 14 The variable [3] conditions in the middle).

[0234] Specifically, when the temperature Tin inside the main body housing is high (Tin1), the control unit 9 sets the drive speed of the first exhaust fan 71 to high speed (V1A). Furthermore, when the temperature Tin inside the main body housing is medium (Tin2), the control unit 9 sets the drive speed of the first exhaust fan 71 to low speed (V1C). Moreover, when the temperature Tin inside the main body housing is low (Tin3), the control unit 9 sets the drive speed of the first exhaust fan 71 to stop (V1D).

[0235] When the temperature Tin inside the main body housing is high temperature Tin1, which is higher than the medium temperature Tin2 and the low temperature Tin3, the temperature inside the main body housing 2, such as the processing unit PU, can be effectively cooled by setting the drive speed of the first exhaust fan 71 to high speed V1A, which is higher than the low speed V1C.

[0236] In this embodiment, when the temperature Tin inside the main body housing is high at Tin1, the control unit 9 sets the drive speed of the first exhaust fan 71 to high speed V1A, but is not limited to this. That is, when the temperature Tin inside the main body housing is high at Tin1, the control unit 9 can set the drive speed of the first exhaust fan 71 to a speed higher than low speed V1C, which is between high speed V1A and low speed V1C.

[0237] Furthermore, when the temperature Tin inside the main body housing is at a medium temperature Tin2, the control unit 9 sets the drive speed of the first exhaust fan 71 to a low speed V1C, but is not limited to this. That is, when the temperature Tin inside the main body housing is at a medium temperature Tin2, the control unit 9 can make the drive speed of the first exhaust fan 71 lower than the drive speed of the first exhaust fan 71 at a high temperature Tin1 and higher than the low speed V1C.

[0238] Furthermore, when the temperature Tin inside the main body housing is low (Tin3), the control unit 9 sets the drive speed of the first exhaust fan 71 to a stop (V1D), but it is not limited to this. That is, when the temperature Tin inside the main body housing is low (Tin3), the control unit 9 can set the drive speed of the first exhaust fan 71 to a speed lower than the drive speed of the first exhaust fan 71 at the medium temperature (Tin2) and higher than the stop (V1D).

[0239] In addition, when the image forming apparatus 1 is in standby mode, the control unit 9 controls the operation of the first exhaust fan 71 in the same way as when it determines that the rear cover 29 is in the open position.

[0240] [Control of the second exhaust fan's operation in standby mode]

[0241] When the image forming apparatus 1 is in standby mode, the control unit 9 controls the operation of the second exhaust fan 72 as follows.

[0242] like Figure 9 As shown, when the image forming apparatus 1 is in standby mode, the control unit 9 controls the operation of the second exhaust fan 72 when it determines that the rear cover 29 is in the closed position and when it determines that the rear cover 29 is in the open position, so that the drive speed of the second exhaust fan 72 is stopped (V2D). This suppresses the power consumption of the image forming apparatus 1.

[0243] [Control of the intake fan's operation in standby mode]

[0244] When the image forming apparatus 1 is in standby mode, the control unit 9 controls the operation of the suction fan 77 as follows.

[0245] like Figure 9 As shown, when the image forming apparatus 1 is in standby mode, the control unit 9 controls the operation of the suction fan 77 to make the drive speed high speed V3A when it determines that the rear cover 29 is in the closed position and when it determines that the rear cover 29 is in the open position. As a result, the air drawn in by the suction fan 77 can be guided to the processing unit PU, thereby cooling the processing unit PU.

[0246] [Control of the first exhaust fan's operation in sleep mode]

[0247] If the image forming apparatus 1 enters standby mode and no print command is received within a specified time, it transitions to sleep mode. While the image forming apparatus 1 is in sleep mode, the control unit 9 stops powering on the fuser 60. As a result, the temperature of the fuser 60 decreases to a temperature lower than its standby temperature.

[0248] When the image forming apparatus 1 is in a sleep state, the control unit 9 controls the operation of the first exhaust fan 71 as follows.

[0249] like Figure 9 , Figure 14 As shown, when the image forming apparatus 1 is in a dormant state, the control unit 9, upon determining that the rear cover 29 is in the closed position, controls the operation of the first exhaust fan 71 so that the drive speed varies according to the temperature Tin inside the main body housing. Figure 14 The variable [3] conditions in the middle).

[0250] Specifically, when the temperature Tin inside the main body housing is high (Tin1), the control unit 9 sets the drive speed of the first exhaust fan 71 to high speed (V1A). Furthermore, when the temperature Tin inside the main body housing is medium (Tin2), the control unit 9 sets the drive speed of the first exhaust fan 71 to low speed (V1C). Moreover, when the temperature Tin inside the main body housing is low (Tin3), the control unit 9 sets the drive speed of the first exhaust fan 71 to stop (V1D).

[0251] When the temperature Tin inside the main body housing is high temperature Tin1, which is higher than the medium temperature Tin2 and the low temperature Tin3, the temperature inside the main body housing 2, such as the processing unit PU, can be effectively cooled by setting the drive speed of the first exhaust fan 71 to high speed V1A, which is higher than the low speed V1C.

[0252] In this embodiment, when the temperature Tin inside the main body housing is high at Tin1, the control unit 9 sets the drive speed of the first exhaust fan 71 to high speed V1A, but is not limited to this. That is, when the temperature Tin inside the main body housing is high at Tin1, the control unit 9 can set the drive speed of the first exhaust fan 71 to a speed higher than low speed V1C, which is between high speed V1A and low speed V1C.

[0253] Furthermore, when the temperature Tin inside the main body housing is at a medium temperature Tin2, the control unit 9 sets the drive speed of the first exhaust fan 71 to a low speed V1C, but is not limited to this. That is, when the temperature Tin inside the main body housing is at a medium temperature Tin2, the control unit 9 can make the drive speed of the first exhaust fan 71 lower than the drive speed of the first exhaust fan 71 at a high temperature Tin1 and higher than the low speed V1C.

[0254] Furthermore, when the temperature Tin inside the main body housing is low (Tin3), the control unit 9 sets the drive speed of the first exhaust fan 71 to a stop (V1D), but it is not limited to this. That is, when the temperature Tin inside the main body housing is low (Tin3), the control unit 9 can set the drive speed of the first exhaust fan 71 to a speed lower than the drive speed of the first exhaust fan 71 at the medium temperature (Tin2) and higher than the stop (V1D).

[0255] In addition, when the image forming apparatus 1 is in a sleep state, the control unit 9 controls the operation of the first exhaust fan 71 in the same way as when it determines that the rear cover 29 is in the closed position when it determines that the rear cover 29 is in the open position.

[0256] [Control of the second exhaust fan's operation in sleep mode]

[0257] When the image forming apparatus 1 is in a sleep state, the control unit 9 controls the operation of the second exhaust fan 72 as follows.

[0258] like Figure 9 As shown, when the image forming apparatus 1 is in a sleep state, the control unit 9 controls the operation of the second exhaust fan 72 when it determines that the rear cover 29 is in the closed position and when it determines that the rear cover 29 is in the open position, so that the drive speed of the second exhaust fan 72 is stopped (V2D). This suppresses the power consumption of the image forming apparatus 1.

[0259] [Control of the intake fan's operation in sleep mode]

[0260] When the image forming apparatus 1 is in a sleep state, the control unit 9 controls the operation of the intake fan 77 as follows.

[0261] like Figure 9 As shown, when the image forming apparatus 1 is in a sleep state, the control unit 9 controls the operation of the suction fan 77 to make the drive speed stop V3D when it determines that the rear cover 29 is in the closed position and when it determines that the rear cover 29 is in the open position. As a result, the power consumption of the image forming apparatus 1 can be suppressed.

Claims

1. An image forming apparatus, comprising: A body housing having an opening; A cover for opening and closing the opening; The processing unit includes a photosensitive drum that can rotate about an axis and a developer that supplies toner to the photosensitive drum for forming a toner image on a sheet. A fuser, viewed from the axial direction of the photosensitive drum, is disposed between the cover and the processing unit, and is used to heat and fuse the sheet on which a toner image has been formed; A first exhaust fan is used to exhaust air from the body housing and is positioned above the fuser when viewed from the axial direction. The second exhaust fan is used to exhaust the air inside the main housing and is positioned below the fuser when viewed from the axial direction. as well as The control unit is capable of performing the printing action that forms an image on the sheet. When the control unit performs the printing operation with the cover closed, it sets the drive speed of the second exhaust fan to a speed greater than or equal to the first speed. When the control unit performs the printing operation with the cover open, it sets the drive speed of the second exhaust fan to a second speed that is lower than the first speed.

2. The image forming apparatus according to claim 1, characterized in that, The second speed is a stop.

3. The image forming apparatus according to claim 1 or 2, characterized in that, It also includes a substrate positioned overlapping the second exhaust fan when viewed from the axial direction. The control unit can change the drive speed of the second exhaust fan within a range between the first speed and a third speed higher than the first speed, based on the temperature of the substrate.

4. The image forming apparatus according to claim 1 or 2, characterized in that, When the control unit performs the printing operation with the cover closed, it sets the drive speed of the first exhaust fan to a speed that varies depending on the temperature inside the main body housing, between a fourth speed and a fifth speed higher than the fourth speed. When the control unit performs the printing operation with the cover open, it sets the drive speed of the first exhaust fan to the fourth speed.

5. The image forming apparatus according to claim 3, characterized in that, When the control unit performs cooling control to suppress temperature rise within the body housing, Stop printing on the sheet. With the cover closed, the second exhaust fan is driven at the third speed. With the cover open, the second exhaust fan is driven at a speed lower than the third speed.

6. The image forming apparatus according to claim 5, characterized in that, When the control unit performs the cooling control while the cover is open during the printing operation, after a first time has elapsed since the start of the cooling control, it sets the drive speed of the second exhaust fan to a speed higher than the second speed.

7. The image forming apparatus according to claim 5 or 6, characterized in that, When the temperature inside the main body housing is above a first temperature, the control unit performs the cooling control.

8. The image forming apparatus according to claim 5 or 6, characterized in that, It also includes a substrate positioned overlapping the second exhaust fan when viewed from the axial direction, the substrate being provided with a sensor for detecting the temperature of the substrate. The control unit performs the cooling control when the temperature of the substrate is above the second temperature.

9. The image forming apparatus according to claim 1 or 2, characterized in that, Also includes: An intake fan is used to draw air into the main body housing; as well as A conduit is used to guide air drawn into the main housing along the axial direction to the processing unit.

10. The image forming apparatus according to claim 1, characterized in that, When the cover is in the open position, the cover includes a disc for supporting the sheet material discharged from the body housing.

Images