Image forming apparatus

Abstract

To solve the problem in which an exchange of a belt is difficult when a roller is inclined in a steering control of the belt by moving the belt in a width direction by tilting at least one roller among a plurality of rollers suspending the belt.SOLUTION: An image formation device of the present invention improves an exchangeability of a belt by returning a tilt of the belt to a reference position when the power is turned off.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine, which has a fixing device for fixing a toner image on a recording material and a recording material cooling device capable of cooling the recording material discharged from the fixing device.

Background Art

[0002] Conventionally, in an image forming apparatus that forms an image on a recording material, a belt conveyance device that sandwiches and conveys the recording material using an endless belt (hereinafter simply referred to as a belt) suspended by a plurality of rollers has been adopted. For example, in order to prevent adhesion between the loaded recording materials, a recording material cooling device has been proposed that cools the belt that sandwiches and conveys the recording material conveyed from the fixing device and lowers the temperature of the recording material after toner image fixing through the cooled belt (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a recording material cooling device using a belt as in Patent Document 1, steering control is performed to prevent the belt from approaching the end of the roller by tilting at least one roller out of the plurality of rollers that suspend the belt and reciprocating the belt in the axial direction of the roller. Such steering control is constantly performed when the belt is rotated, and the steering control is stopped when the rotation of the belt is stopped. Therefore, depending on the timing of stopping the steering control, the roller may stop in a tilted state.

[0005] In addition, in a recording material cooling device using a belt, it is necessary to periodically replace the belt for maintenance. When replacing the belt, if the roller is stopped in an inclined state as described above, there is a problem that it is difficult to replace the belt.

[0006] Particularly, as shown in FIG. 13, when the roller is tilted and stopped at a position where the belt is moved to the back side, in order to move the belt to the back side in the axial direction of the roller, the pressure applied to the belt on the front side in the axial direction of the roller is high. When trying to pull out the belt from the front side in the axial direction of the roller in this state, the belt is caught on the front side, and it is difficult to replace the belt.

Means for Solving the Problem

[0007] An image forming apparatus having an image forming unit that forms a toner image on a recording material and a fixing device that fixes the toner image on the recording material, and capable of transitioning between a power-off state and a standby state in which image formation by the image forming unit is possible, including a belt, a conveyance unit that forms a conveyance nip together with the belt and sandwiches and conveys the recording material that has passed through the fixing device with the nip, a heat sink that contacts the inner peripheral surface of the belt, a first roller and a second roller that suspend the belt, and a belt position detection unit that detects the position of the belt in a width direction orthogonal to the thickness direction of the belt and the conveyance direction of the recording material sandwiched in the nip, a steering unit that swings the first roller with respect to the second roller so as to move the belt in the width direction with respect to the first roller according to the detection result of the position detection unit, A switch that can be switched on and off by the user, and is characterized in that the steering unit when the switch is switched from ON to OFF, the rotation axis of the first roller is made substantially parallel to the rotation axis of the second roller, and the image forming apparatus transitions to the power-off state after the rotation axis of the first roller becomes substantially parallel to the rotation axis of the second roller. is as described above. Also, one aspect of the image forming apparatus of the present invention includes an image forming unit that forms a toner image on a recording material and a fixing device that fixes the toner image to the recording material, and is an image forming apparatus that can transition between a standby state in which image formation by the image forming unit is possible and a power-saving state in which power consumption is smaller than in the standby state. The image forming apparatus includes a belt, a conveyance unit that forms a conveyance nip together with the belt and sandwiches and conveys the recording material that has passed through the fixing device at the nip, a heat sink that contacts the inner peripheral surface of the belt, a first roller and a second roller that suspend the belt, a belt position detection unit that detects the position of the belt in the width direction that is orthogonal to the thickness direction of the belt and the conveyance direction of the recording material sandwiched at the nip, a steering unit that swings the first roller with respect to the second roller in accordance with the detection result of the position detection unit so as to move the belt in the width direction with respect to the first roller, and an operation unit that can be operated by the user. The steering unit makes the rotation axis of the first roller substantially parallel to the rotation axis of the second roller when a transition instruction to the power-saving state is input from the user via the operation unit, and the image forming apparatus transitions to the power-saving state after the rotation axis of the first roller becomes substantially parallel to the rotation axis of the second roller. This is the gist of the invention.

Advantages of the Invention

[0008] In the present invention, it is possible to provide an image forming apparatus with improved replaceability of the belt of the cooling device.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Modes for Carrying Out the Invention

[0010] <Image Forming Apparatus> Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, an image forming apparatus to which the cooling device of the present embodiment is applicable will be described with reference to FIG. 1. The image forming apparatus 100 shown in FIG. 1 is an electrophotographic tandem type full-color printer. The image forming apparatus 100 includes image forming units Pa, Pb, Pc, and Pd that form yellow, magenta, cyan, and black images, respectively. The image forming apparatus 100 forms a toner image on a recording material S according to image information from a document reading device (not shown) or an external device (not shown) such as a personal computer communicably connected to the image forming apparatus 100. Examples of the recording material S include various types of sheet materials such as plain paper, thick paper, rough paper, embossed paper, coated paper, plastic film, and cloth.

[0011] The conveyance process of the recording material of the image forming apparatus 100 will be described. The recording material S is stored in a stacked manner in the paper feed cassette 10 and is fed out from the paper feed cassette 10 by the paper feed roller 13 in accordance with the image forming timing. The recording material S fed out by the paper feed roller 13 is conveyed to the registration roller 12 disposed in the middle of the conveyance path 114. Then, after performing skew correction and timing correction of the recording material S at the registration roller 12, the recording material S is sent to the secondary transfer unit T2. The secondary transfer unit T2 is a transfer nip portion formed by the secondary transfer inner roller 14 and the secondary transfer outer roller 11, and a toner image is transferred onto the recording material in response to the application of a secondary transfer voltage to the secondary transfer outer roller 11.

[0012] Regarding the conveyance process of the recording material S up to the secondary transfer unit T2 described above, the image formation process of the image that is sent to the secondary transfer unit T2 at the same timing will be described. First, the image forming units will be described. The image forming units Pa, Pb, Pc, and Pd for each color are substantially configured in the same manner except that the colors of the toner used in the developing devices 1a, 1b, 1c, and 1d are different, being yellow, magenta, cyan, and black, respectively. Therefore, hereinafter, the black image forming unit Pd will be described as a representative, and the description of the other image forming units Pa, Pb, and Pc will be omitted.

[0013] The image forming unit Pd mainly includes a developing device 1d, a charging device 2d, a photosensitive drum 3d, a photosensitive drum cleaner 4d, an exposure device 5d, etc. The surface of the photosensitive drum 3d rotated in the direction of arrow R1 in the figure is uniformly charged on the surface in advance by the charging device 2d, and then an electrostatic latent image is formed by the exposure device 5d driven based on the signal of the image information. Next, the electrostatic latent image formed on the photosensitive drum 3d is developed into a toner image using a developer by the developing device 1d. Then, in response to the application of a primary transfer voltage to the primary transfer roller 6d disposed with the image forming unit Pd and the intermediate transfer belt 20 interposed therebetween, the toner image formed on the photosensitive drum 3d is primarily transferred onto the intermediate transfer belt 20. The slightly remaining primary transfer residual toner on the photosensitive drum 3d is recovered by the photosensitive drum cleaner 4d and prepared for the next image forming process again.

[0014] With the above-described conveyance process and image forming process respectively explained, the timing of the recording material S and the full-color toner image coincides in the secondary transfer unit T2, and secondary transfer is performed. Thereafter, the recording material S is conveyed to the fixing device 30, and a predetermined pressure and heat amount are applied to fix the toner image on the recording material. The fixing device 30 heats and presses the conveyed recording material S by sandwiching and conveying the recording material S on which the toner image is formed, so as to fix the toner image to the recording material S. That is, the toner of the toner image formed on the recording material S is melted and mixed by heating and pressing, and is fixed to the recording material S as a full-color image. In this way, a series of image forming processes are completed. In the present embodiment, the image forming units Pa, Pb, Pc, Pd, the intermediate transfer belt 20, the inner secondary transfer roller 14 and the outer secondary transfer roller 11 are an example of an image forming unit that forms an image on a recording material using toner.

[0015] In the case of the present embodiment, the recording material S on which the toner image is fixed is conveyed from the fixing device 30 to the recording material cooling device 50 and cooled. For example, the temperature of the recording material S is about 90°C immediately before the recording material cooling device 50, but is reduced to about 60°C after passing through the recording material cooling device 50. Details of the recording material cooling device 50 will be described later.

[0016] When the toner image is fixed on the recording material S, in the case of single-sided image formation, the recording material S is sandwiched and conveyed by a pair of discharge rollers 105 and discharged onto the paper discharge tray 120 as it is. On the other hand, in the case of double-sided image formation, the conveying path is switched from the path leading to the paper discharge tray 120 to the double-sided conveyance path 111 by a switching member 110 (referred to as a flapper, etc.), and the recording material S sandwiched and conveyed by the discharge rollers 105 is sent to the double-sided conveyance path 111. Thereafter, the front and rear ends are reversed by the reversing roller 112 and sent to the conveyance path 114 again via the double-sided path 113. Since the subsequent conveyance and the image formation process on the back surface (second side) are the same as described above, the description is omitted.

[0017] Next, based on FIG. 2, an example of the hardware configuration of the image forming apparatus 100 according to an embodiment of the present invention will be described. FIG. 2 is a block diagram showing an example of the hardware configuration of the image forming apparatus 100 according to an embodiment of the present invention.

[0018] First, in the image forming apparatus 100, a main control unit 600 is provided as a part that controls the operation of the image forming apparatus 100. The main control unit 600 is a substrate having, for example, a CPU 601 as a control element. The main control unit 600 overall controls the entire image forming apparatus 100. The main control unit 600 may be divided into a plurality of types according to functions, such as a part that performs overall control, a part that performs communication control, a part that performs image processing, and an engine control unit that controls printing by turning on / off motors that rotate various rotators for image formation. In this description, a form in which these control units are combined will be shown and described. Note that the main control unit is an example of a control unit.

[0019] The main control unit 600 has a storage unit 602. The storage unit 602 can store, in addition to the programs and data for controlling the image forming apparatus 100, image data and the like. For example, the storage unit 602 is formed by combining volatile and non-volatile storage devices such as a RAM, a ROM, an HDD, and a flash ROM. The CPU 601 executes arithmetic processing, transmits and receives control signals based on the programs and data stored in the storage unit 602, and controls the image forming apparatus 100. Incidentally, the paper type setting such as plain paper or coated paper input from the operation panel 40 or the like by the user is also stored in the storage unit 602 by the CPU 601.

[0020] Also, the main control unit 600 is communicably connected to each unit of the document conveyance unit 900, the image reading unit 901, and the image forming apparatus 100, and controls each unit. Further, the main control unit 600 is communicably connected to the operation panel 40. As a result, the settings and input contents made on the operation panel 40 are transmitted to the main control unit 600. The main control unit 600 gives instructions so that each unit operates according to the set contents, and operates each unit of the image forming apparatus 100.

[0021] Furthermore, the main control unit 600 is connected to a communication unit 903 which is an interface for communicating with a computer 200 (for example, a personal computer) or a counterpart FAX apparatus 300 via a network, a cable, or a communication network. As a result, the image forming apparatus 100 receives image data and the like from the computer 200 and prints them (printer function). Also, the image data read by the image reading unit 901 can be stored in the storage unit 602, transmitted to the computer 200 (scanner function), and transmitted and received of image data with an external FAX apparatus 300 (FAX function).

[0022] Further, the image forming apparatus 100 is provided with a power supply unit 420. The power supply unit 420 is connected to, for example, a commercial power supply and generates various voltages. Also, a main switch 410 for turning on / off the connection between the commercial power supply and the power supply unit 420 is provided (for example, on the side surface of the image forming apparatus 100). The main switch 410 can be operated by a user or a service technician, and an operation for switching the main switch 410 from ON to OFF serves as a trigger for shifting the image forming apparatus 100 to the power-off state. Also, an operation for switching the main switch 410 from OFF to ON serves as a trigger for shifting the image forming apparatus 100 to the standby state.

[0023] The power supply unit 420 has, for example, a plurality of power conversion circuits 422 including a rectifier circuit, a transformer, a converter, a smoothing circuit, etc., and generates a plurality of types of voltages necessary for operating the image forming apparatus 100. For example, the power supply unit 420 generates DC24V for motor drive, DC5V for driving circuit elements in the main control unit 600, etc., DC3.3V, etc., and supplies them to each part within the image forming apparatus 100.

[0024] Also, when each unit of the image reading unit 901, the image generation unit 902, and the image forming apparatus 100 has not been operating for a predetermined time, or when an instruction for image formation is received, the main control unit 600 shifts to a power saving state with lower power consumption than the standby state in which the image forming operation can be started immediately, and stops the power supply to a predetermined part by the power control unit 421 to achieve power saving. In the present embodiment, the main control unit 600 monitors each unit of the image reading unit 901, the image generation unit 902, and the image forming apparatus 100 and shifts to the power saving state, but the monitoring target is not limited to this. Further, it may also follow an instruction to shift to the power saving state from the operation unit 40. Thus, in the present embodiment, the image forming apparatus 100 that can transition to three states of the power-off state, the power saving state, and the standby state has been described, but a configuration having two power saving states may also be used.

[0025] <Recording material cooling device> Next, the recording material cooling device 50 will be described with reference to FIG. 3. As shown in FIG. 3, the recording material cooling device 50 includes a first unit 501U having an endless first belt 501, and a second unit 502U having an endless second belt 502 that sandwiches and conveys the first belt 501 and the recording material S. For example, the first belt 501 and the second belt 502 are formed of high-strength polyimide, have a thickness of 100 μm, and a set perimeter of 942 mm. The recording material cooling device 50 also has a heat sink 503 that cools the first belt 501. Here, the heat sink 503 is an example of a cooling member that cools the first belt 501.

[0026] In the case of this embodiment, the heat sink 503 is in contact with the first belt 501 that contacts the recording material S on the surface side where the toner image is formed in the secondary transfer portion T2 (see FIG. 1).

[0027] The first belt 501 is wound around a plurality of first belt suspension rollers 501a to 501e, and at least one of the first belt suspension rollers 501a to 501e is rotated by receiving drive from a belt drive motor 511. The second belt 502 is wound around a plurality of second belt suspension rollers 502a to 502e, and at least one of the second belt suspension rollers 502a to 502e is rotated by the belt drive motor 511. That is, the first belt 501 is suspended by the first belt suspension rollers 501a to 501e, and the second belt 502 is suspended by the second belt suspension rollers 502a to 501d.

[0028] In the case of this embodiment, the second belt suspension roller 502e rotated by the belt drive motor 511 corresponds to a drive roller that drives the second belt 502. For example, silicone rubber with a thickness of 100 μm is formed on the outer peripheral surface of an aluminum roller with a diameter of 24.8 mm, and the friction coefficient with the polyimide belt is set to 1.1. As a result, the second belt 502 rotates in the direction of arrow C in the figure.

[0029] In addition, a drive train 504a is installed at the axial end of the second belt suspension roller 502e, and the drive trains 504a to 504d transmit driving force to the first belt 501. In the case of this embodiment, the second belt suspension rollers 502a to 502d correspond to idler rollers that suspend the second belt 502. For example, they are aluminum rollers with a diameter of 25 mm, and the friction coefficient with the polyimide belt is set to 0.1. On the other hand, the first belt 501 is looped around a plurality of first belt suspension rollers 501a to 501e and is in contact with the second belt 502.

[0030] And at least one of the first belt suspension rollers 501a to 501e is rotated by the driving force of a belt drive motor 511 via the drive trains 504a to 504d. In the case of this embodiment, the first belt suspension roller 501e rotated by the drive train 504d corresponds to a drive roller that drives the first belt 501. For example, silicone rubber with a thickness of 100 μm is formed on the outer peripheral surface of an aluminum roller with a diameter of 24.8 mm, and the friction coefficient with the polyimide belt is set to 1.1. Thereby, the first belt 501 rotates in the direction of arrow B in the figure.

[0031] In this way, the first belt 501 and the second belt 502 are rotated in the same direction at the cooling nip portion T4 by the belt drive motor 511 which is the same drive source. In the case of this embodiment, the second belt suspension rollers 502a to 502d correspond to idler rollers that suspend the second belt 502. For example, they are aluminum rollers with a diameter of 25 mm, and the friction coefficient with the polyimide belt is set to 0.1. In addition, the first belt suspension roller 501e and the second belt suspension roller 502e do not form a nip with each other.

[0032] The drive trains 504a to 504d are gears. Also, any one of the drive trains 504a to 504d has a one-way clutch 505 that cuts off the transmission of the driving force depending on the direction of the driving force. In the case of this embodiment, the one-way clutch 505 is embedded inside the drive train 504d, and the rotation axis of the drive train 504d and the rotation axis of the one-way clutch 505 are in the same axial position.

[0033] Also, when the first belt suspension roller 501e is rotated counterclockwise in the figure, the one-way clutch 505 is set in a state where it does not lock with the shaft end of the first belt suspension roller 501e. For example, when the belt drive motor 501 is rotated so that the second belt 502 rotates in the direction of arrow C in the figure, the drive train 504a rotates counterclockwise in the figure, the drive train 504b rotates clockwise in the figure, the drive train 504c rotates counterclockwise in the figure, and the drive train 504d rotates clockwise in the figure.

[0034] When the drive train 504d rotates clockwise, the one-way clutch 505 locks with the shaft end of the first belt suspension roller 501e, and the first belt suspension roller 501e rotates clockwise. When the first belt suspension roller 501e rotates clockwise, as described above, the first belt 501 rotates in the direction of arrow B in the figure.

[0035] Subsequently, the recording material cooling device 50 will be described with reference to FIGS. 4 and 5. A first unit 501U for suspending the first belt 501 by the first belt suspension rollers 501a to 501e and a second unit 502U for suspending the second belt 502 by the second belt suspension rollers 502a to 502e form a cooling nip portion T4. The cooling nip portion T4 is an example of a conveying nip that sandwiches and conveys a sheet.

[0036] The second unit 502U has a drive train 504a rotatably supported via a bearing (not shown) at the shaft end of the second belt suspension roller 502e and a rotation support member 506. The rotation support member 506 has a second idler shaft 507 fixed to the rotation support member 506, and the second idler shaft 507 has a drive train 504b rotatably supported via a bearing (not shown). The drive train 504a and the drive train 504b are arranged so as to be able to transmit a driving force.

[0037] In addition, the first unit 501U has a first idler shaft 512 fixed to the first unit 501U, and a drive train 504c rotatably supported on the first idler shaft 512 via a bearing (not shown). At the shaft end of the first belt suspension roller 501e, there is a drive train 504d rotatably supported via a one-way clutch 505 shown in FIG. 1. The drive train 504c and the drive train 504d are arranged so as to be able to transmit a driving force.

[0038] In the case of this embodiment, the first belt suspension roller 501a and the second belt suspension roller 502a are steering rollers provided to control the approach of the first belt 501 and the second belt 502, respectively. For example, the steering roller 501a has an acrylic layer with a thickness of 100 μm formed on the outer peripheral surface of an aluminum roller with a diameter of 24.8 mm, and the friction coefficient with a polyimide belt is set to 0.5. These steering rollers 501a and 502a press the first belt 501 and the second belt 502 from the inner peripheral side toward the outer side so that the tensions of the first belt 501 and the second belt 502 are about 39.2 N (about 4 kgf), respectively.

[0039] To do so, the steering roller 501a is biased by a spring 507a (FIG. 3), and the steering roller 502a is biased by a spring 508a (FIG. 3).

[0040] FIG. 7(a) is a perspective view of the recording medium cooling device 50 as viewed from the back side (rear side) of the image forming apparatus 100. FIG. 7(b) is a schematic cross-sectional view of the steering roller 501a. As shown in FIG. 7(a), a steering mechanism 400 is provided on the back side of the recording medium cooling device 50 for the steering rollers 501a and 502a. By swinging each of them about the center of the rotation axis direction (width direction) of the steering rollers 501a and 502a as a swing center, the steering control of the first belt 501 and the second belt 502 can be performed. The steering mechanism 400 is an example of a steering unit.

[0041] As shown in FIG. 7(b), the steering roller 501a is rotatably supported by the roller holder 800. The roller holder 800 is swingable about the swing shaft 802 with respect to the support sheet metal 801. The swing shaft 802 is provided at the center between the front end and the rear end of the roller holder 800 in the rotational axis direction of the steering roller 501a. Further, a shaft 465 is fixed to the roller holder 800, and the roller holder 800 can be swung about the swing shaft 802 by operating the shaft 465 by the steering mechanism 400. Incidentally, the support sheet metal 801 is supported by the rear side plate 461 provided on the rear side of the recording material cooling device 5 and the front side plate 462 provided on the front side. By operating an operation lever (not shown), the support sheet metal 801 can move the steering roller 501a together with the roller holder 800 to the inner peripheral side of the belt to release the pressing of the steering roller 501a against the first belt 501. That is, the state in which the first belt 501 is suspended with tension can be released. Here, the steering roller 501a has been described as an example, but the steering roller 502a of the second unit 502U also has the same configuration.

[0042] In the present embodiment, the configuration in which the steering mechanism 400 is provided in the recording material cooling device 50 will be described as an example, but a configuration in which it is provided in a frame (not shown) of the image forming apparatus 100 that supports the recording material cooling device 50 may also be used. Incidentally, the steering control of the first belt 501 and the second belt 502 will be described later. Further, although the steering mechanism 400 is shown as having a configuration for operating the shaft 465 provided on the roller holder 800, a configuration for directly operating the shaft of the steering roller 501a to perform steering control may also be used.

[0043] Here, in the present embodiment, the steering rollers 501a and 502a are examples of the first roller, and the first belt suspension rollers 501b to 501e and the second belt suspension rollers 502b to 502e are examples of the second roller. As described above, in the present embodiment, the first belt suspension rollers 501b to 501e and the second belt suspension rollers 52b to 502e do not swing, and both ends of their respective roller shafts are held by the front and rear frames of the first unit 501U and the second unit 502U. Further, the steering roller 502a is an example of the third roller, and the second belt suspension rollers 502b to 502e are examples of the fourth roller.

[0044] Also, on the inner peripheral side of the second belt 502, pressing rollers 509a and 509b for pressing the second belt 502 toward the heat sink 503 are provided. The pressing rollers 509a and 509b press the second belt 502 with a pressing force of, for example, 9.8 N (1 kgf), thereby surely bringing the first belt 501 into contact with the heat sink 503 (specifically, the heat receiving portion 503a described later) via the second belt 502.

[0045] The recording material S on which the toner image is fixed is sandwiched between the first belt 501 and the second belt 502 and is conveyed in the conveying direction (the direction of arrow D in the figure) according to their rotation. At that time, the recording material S passes through the cooling nip portion T4 formed by the contact of the first belt 501 and the second belt 502. In the case of the present embodiment, the first belt 501 is cooled by the heat sink 503.

[0046] The heat sink 503 is arranged so as to contact the inner surface of the first belt 501 at the location where the cooling nip portion T4 is formed in order to efficiently cool the recording material S. The recording material S is cooled by the heat sink 503 via the first belt 501 when passing through the cooling nip portion T4. For example, when the temperature of the recording material S is about 90°C before passing through the recording material cooling device 50, the recording material S is cooled so as to be about 60°C after passing through the recording material cooling device 50. Along with the cooling of the recording material S, the toner on the recording material S is cooled and fixed.

[0047] The heat sink 503 is a heat dissipation plate formed of a metal such as aluminum. The heat sink 503 has a heat receiving portion 503a that contacts the first belt 501 and takes heat from the first belt 501, a heat radiating portion 503b that radiates heat, and a fin base 503c that conducts heat from the heat receiving portion 503a to the heat radiating portion 503b.

[0048] The heat radiating portion 503b is formed of a number of heat radiating fins in order to increase the contact area with air and promote efficient heat dissipation. For example, the heat radiating fins are set to have a thickness of 1 mm, a height of 100 mm, and a pitch of 5 mm, and the fin base 503c is set to have a thickness of 10 mm.

[0049] In addition, in order to forcibly cool the heat sink 503 itself, a cooling fan 513 is provided that blows air toward the heat sink 503 (specifically, the heat radiating portion 503b). The air volume of this cooling fan 513 is set to, for example, 2 m 3 / min. Note that the cooling of the heat sink 503 is not limited to the cooling fan 513, and may be configured to be cooled by, for example, a cooling medium.

[0050] In the case of such a recording medium cooling device 500, due to variations in the dimensional tolerances of the first belt suspension rollers 501a to 501e that support the first belt 501, variations in the dimensional tolerances of a pair of frames that support both ends of the first belt suspension rollers 501a to 501e, etc., the first belt 501 moves toward the end side of the first belt suspension rollers 501a to 501e in the width direction. Similarly, due to variations in the dimensional tolerances of each of the second belt suspension rollers 502a to 502e that support the second belt 502, variations in the dimensional tolerances of a pair of frames that support both ends of the second belt suspension rollers 502a to 502e, etc., the second belt 502 moves toward the end side of the first belt suspension rollers 501a to 501e in the width direction. As a result, there was a risk that the ends of the first belt 501 and the second belt 502 would rub against one of the pair of frames provided at both ends in the width direction of the recording medium cooling device 50. Therefore, one of the plurality of rollers that support the first belt 501 and the second belt 502 is used as a steering roller and is swung relative to the other rollers to execute steering control for reciprocally moving the first belt 501 and the second belt 502 in the width direction. This suppresses the ends of the first belt 501 and the second belt 502 in the width direction from rubbing against the aforementioned frames.

[0051] In order to perform the steering control in this way, sensor units 390 and 391 are provided to detect the end positions of the belts in the width direction of the first belt 501 and the second belt 502 respectively. Here, the width direction of the first belt 501 is the rotation axis direction of the first belt suspension rollers 501a to 501e, and the width direction of the second belt 502 is the rotation axis direction of the second belt suspension rollers 502a to 502e. Based on the detection signals of these sensor units 390 and 391, the end positions of the first belt 501 and the second belt 502 in the width direction during rotation are detected. The sensor unit 390 can detect the end position of the first belt 501 at a plurality of locations in the width direction so as to detect how much the central part of the first belt 501 is displaced with respect to the central part of the first belt suspension rollers 501a to 501e. Similarly, the sensor unit 391 can also detect the end position of the second belt 502 at a plurality of locations in the width direction so as to detect how much the central part of the second belt 502 is displaced with respect to the central part of the second belt suspension rollers 502a to 502e. Then, based on the end positions detected by the sensor units 390 and 391, the steering mechanism 400 described above is operated so that the first belt 501 and the second belt 502 are respectively positioned at the center in the width direction. That is, based on the detection signals of the sensor units 390 and 391, the angles of the steering rollers 501a and 502a are adjusted. Here, the sensor units 390 and 391 are an example of a belt position detection unit. Also, the "width direction" in the present embodiment is a direction orthogonal to the thickness direction of the first belt 501 and the conveyance direction of the sheet sandwiched between the cooling nip portions T4, and is the rotation axis direction of the steering rollers 501a and 502a. Note that the "width direction" is also the rotation axis direction of the first belt suspension rollers 501b to 501e and the rotation axis direction of the second belt suspension rollers 502b to 502e.

[0052] Regarding the steering mechanism 400, since the configurations of the first unit 501U and the second unit 502U are substantially the same, the first unit 501U will be described here as a representative with reference to FIG. 8.

[0053] The steering control stepping motor 452, the worm gear 466, and the sector gear 460 are supported by the rear side plate 461 on the back side of the cooling device 500. The shaft 465 is fixed to the roller holder 800 that supports the shaft of the first belt suspension roller 501a. 390 is a belt end detection sensor.

[0054] When the steering control stepping motor 452 is driven in the CW direction (clockwise), the worm gear 466 rotates, and the orientation of the sector gear 460 changes downward about the axis. Accordingly, since the shaft 465 moves downward, the roller holder 800 to which the shaft 465 is fixed swings about the swing axis 802, and the steering roller 501a supported by the roller holder 800 tilts toward the back side in the rotational axis direction of the steering roller 501a. As a result, as the first belt 501 rotates, the first belt 501 moves toward the back side. In the present embodiment, the back side is the side closer to the opening / closing mechanism 510 in the rotational axis direction of the steering roller 501a. Also, the back side is the back side of the image forming apparatus 100.

[0055] Conversely, when the steering control stepping motor 452 is driven in the CCW direction (counterclockwise), the worm gear 466 rotates, and the orientation of the sector gear 460 changes upward about the axis. Accordingly, since the shaft 465 moves upward, the roller holder 800 to which the shaft 465 is fixed swings about the swing axis 802, and the steering roller 501a tilts slightly toward the front side in the rotational axis direction of the steering roller 501a. As a result, as the first belt 501 rotates, it moves toward the front side (right direction in the drawing).

[0056] FIG. 9 is a diagram showing the case where the steering roller 501a is tilted to return the position of the first belt 501 of the first unit 501U from a position closer to the back side to the front side. Since the drive for tilting the steering roller 501a is on the back side as described above, the end of the steering roller 501a is raised by the steering control stepping motor 452. Hereinafter, the displacement amount in the height direction of the end of this steering roller 501a is denoted as the displacement amount D of the end of the steering roller 501a. The + direction of the displacement amount D is the upper side and is the direction in which the first belt 501 is moved toward the front side with respect to the axial direction of rotation of the steering roller 501a. The - direction of the displacement amount D is the lower side and is the direction in which the first belt 501 is moved toward the back side with respect to the axial direction of rotation of the steering roller 501a.

[0057] When the displacement amount D of the end changes, the position in the width direction of the first belt 501 tends to move accordingly. Ideally, the first belt 501 is positioned such that the center in the width direction of the first belt 501 is equal to the center in the width direction of the steering roller 501a. At this ideal position, the angle of the steering roller 501a is substantially horizontal, and the displacement amount D described above is in the state of the reference amount ±0.

[0058] Ideally, if the displacement amount D is the reference amount ±0, the belt does not move in the width direction from that position. However, actually, due to various factors such as the dimensional tolerances described above, the first belt 501 moves closer to one end of the steering roller 501a, and the belt moves in the width direction with respect to the suspension roller. Therefore, the position in the state of the reference amount ±0 is defined as the reference position of the steering roller 501a, and the position where the steering HP sensor 453 changes from ON to OFF by the sector gear 460 is set. The steering HP sensor 453 determines that it is ON when it is shielded and OFF when it is not shielded. Here, the steering HP sensor 453 is an example of a steering position detection unit that detects the positions (displacement amounts) of the steering rollers 501a and 501b and the angle with respect to other rollers.

[0059] The displacement D of such a steering roller 501a is determined by the position of the first belt 501 detected by the sensor unit 390. That is, when the first belt 501 is positioned closer to the front side than the center in the width direction, the displacement of the steering roller 501a is set to -, and control is performed to return the first belt 501 to the center in the width direction. Also, when the first belt 501 is positioned closer to the rear side than the center in the width direction, the displacement of the steering roller 501a is set to +, and control is performed to return the first belt 501 to the center in the width direction. In the present embodiment, the sensor unit 390 can detect a total of seven belt positions, three positions on the rear side and three positions on the front side with respect to the center. When the first belt 501 is positioned at the center, the steering mechanism 400 sets the steering roller 501a as the reference position, and when the first belt 501 is positioned at any of the six positions other than the center, the steering roller 501a is tilted to an angle corresponding to that position. For example, when it is positioned closer to the rear side than the center, the angle of the steering roller 501a is changed stepwise according to the position of the first belt 501, such as +0.75°, +1.5°, +1.8°. When the first belt 501 is positioned closer to the front side than the center, the angle of the steering roller 501a is changed stepwise according to the position of the first belt 501, such as -0.75°, -1.5°, -1.8°. That is, the steering mechanism 400 enables the steering roller 501a to swing in the range of +1.8° to -1.8°. In the present embodiment, the swing angle of the steering roller 501a is defined as above, but it is not limited thereto.

[0060] Thus, in the recording medium cooling device 50 having the steering mechanism 400, when replacing the first belt 501 or the second belt 502, if the steering rollers 501a and 501b are in an inclined state, it is difficult to pull out the first belt 501 or the second belt 502, and the workability during belt replacement is poor. In particular, when the steering rollers 501a and 501b stop at an inclination angle such that the first belt 501 or the second belt 502 moves toward the back side of the recording medium cooling device 50, the pressure in the direction of pulling out the first belt 501 and the second belt 502 increases, resulting in poor workability during replacement.

[0061] Also, in the case of having the heat sink 503 on the inner circumference of the conveyor belt like the first belt 501 in the recording medium cooling device 50, the exclusive area of the heat sink 503 inside the conveyor belt is large in order to improve the cooling efficiency. Therefore, even in a configuration where the steering roller 501a is moved to the inner circumferential side of the belt against the biasing force of the spring 507a that presses the steering roller 501a against the inner circumferential surface of the first belt 501 when replacing the first belt 501, the heat sink 503 prevents the movement amount of the steering roller 501a from being sufficiently ensured.

[0062] Therefore, when replacing the first belt 501 with the steering roller 501a in an inclined state, it is difficult to pull out the first belt 501 with respect to the suspension rollers 501a to 501d, and it is difficult to attach a new belt.

[0063] Therefore, in the present embodiment, before the image forming apparatus 100 in which the first belt 501 can be replaced shifts to the power-off state or the power-saving state, the steering roller 501a is returned to the reference position so that the axis of the steering roller 501a and the axes of the other first suspension rollers 501b to 501d are substantially parallel. Here, in the present embodiment, substantially parallel means, for example, when the state of the reference amount ±0 is defined as the parallel state, it also includes a position deviated within a range of ±0.5° with respect to the state of the reference amount ±0. The details regarding the sequence for moving the steering roller 501a to the reference position will be described later.

[0064] Although FIGS. 8 and 9 described the first belt 501 of the first unit 501U, the basic configuration is the same for the second belt 502 of the second unit 502U.

[0065] Also, with reference to FIGS. 4 and 5, a method for removing the recording material S from the recording material cooling device 50 when the recording material S stays in the recording material cooling device 50 and a swinging configuration provided in the drive trains 504a to 504d will be described.

[0066] FIG. 4 shows a state in which the recording material S is being conveyed in the recording material cooling device 50. A first unit 501U for suspending the first belt 501 by the first belt suspension rollers 501a to 501e and a second unit 502U for suspending the second belt 502 by the second belt suspension rollers 502a to 502e form a cooling nip portion T4 (FIG. 3).

[0067] The second unit 502U has a drive train 504a rotatably supported via a bearing (not shown) at the shaft end of the second belt suspension roller 502e and a rotation support member 506. The rotation support member 506 has a second idler shaft 507 fixed to the rotation support member 506, and the second idler shaft 507 has a drive train 504b rotatably supported via a bearing (not shown). The drive train 504a and the drive train 504b are arranged so as to be able to transmit a driving force.

[0068] The rotation support member 506 is connected to a spring member 509 connected to a fixing member 508, and gives tension to the rotation support member 506 rotatably supported via a bearing (not shown) at the shaft end of the second belt suspension roller 502e.

[0069] Further, the first unit 501U has a first idler shaft 512 fixed to the first unit 501U, and a drive train 504c rotatably supported on the first idler shaft 512 via a bearing (not shown). At the shaft end of the first belt suspension roller 501e, there is a drive train 504d rotatably supported via a one-way clutch 505 shown in FIG. 3. The drive train 504c and the drive train 504d are arranged so as to be able to transmit a driving force.

[0070] When the first unit 501U shown in FIG. 4 is in contact with the second unit 502U, the drive train 504b of the second unit 502U can transmit a driving force to the drive train 504c of the first unit 501U.

[0071] The first unit 501U is supported so as to be openable and closable by a rotating shaft (not shown) in the opening and closing mechanism 510, and it is possible to maintain a state of forming the cooling nip portion T4 in FIG. 4 and a state of not forming the cooling nip portion T4 in FIG. 5. FIG. 5 shows a state in which the recording material S staying in the recording material cooling device 50 is removed. The first unit 501U and the second unit 502U are separated without forming the cooling nip portion T4 shown in FIG. 3.

[0072] When the first unit 501U shown in FIG. 5 is separated from the second unit 502U, the drive train 504b of the second unit 502U cannot transmit a driving force to the drive train 504c of the first unit 501U. Further, a rotation support member 506 rotatably supported via a bearing (not shown) at the shaft end of the second belt suspension roller 502e receives tension by a spring member 509 connected to a fixing member 508, and rotates counterclockwise around the rotation center of the second belt suspension roller 502e.

[0073] When the rotation support member 506 rotates counterclockwise, the rotation restricting portion 506b (not shown) of the rotation support member 506 interferes with the second unit front upper side plate 519, and the rotation support member 506 is restricted at a certain angle. This certain angle is set to satisfy the relationship that when transitioning from the state where the cooling nip portion T4 is not formed (FIG. 5) to the state where it is formed (FIG. 4), the drive train 504c of the first unit 501U and the drive train 504b of the second unit 502U can mesh with each other again and transmit the driving force.

[0074] In addition, when the belt drive motor 511 rotates the second belt in the direction of arrow C in FIG. 3, due to the force generated by the drive trains 504b to 504c, the drive train 504b rotates about the axial end of the second belt suspension roller 502e as the rotation center. The arrangement of the drive trains 504a to 504d is set to be constantly biased with respect to the drive train 504c attached to the first unit 501U.

[0075] Using FIGS. 1 and 5 to 7, an explanation will be given of how the recording medium cooling device 50 is fixed. As shown in FIG. 1, the recording medium cooling device 50 is arranged in the device main body 100A.

[0076] The recording medium cooling device 50 has positioning support portions 514, 515 as shown in FIGS. 5 to 6 and positioning support portions 516, 517 as shown in FIG. 7. The recording medium cooling device 50 is supported by the device main body 100A by these positioning support portions 514, 515, 516, 517. In the present embodiment, as shown in FIGS. 5 to 6, convex portions are provided as the positioning support portions 514, 515 on the second unit front lower side plate 518, and the convex portions are fixed so as to contact the flat portion in the device main body 100A. That is, the positioning support portions 514, 515 are members for determining the position with respect to the support frame of the image forming apparatus 100 at the front side position of the recording medium cooling device 50.

[0077] Further, as shown in FIG. 7, shaft-shaped portions were provided as positioning support portions 516 and 517, and the shaft-shaped portions were fixed so as to engage with holes provided in the vertical wall of the apparatus main body 100A. That is, the positioning support portions 516 and 517 are members for determining the position with respect to the frame of the image forming apparatus 100 at the rear side position of the recording material cooling device 50.

[0078] <Sequence for moving the steering roller to the reference position> Next, a sequence for moving the steering roller 501a in the present embodiment to the reference position (displacement amount D in FIG. 9 is ±0) will be described with reference to FIG. 10. Since the configurations of the first unit 501U and the second unit 502U are substantially the same, the steering roller 501a of the first unit 501U will be described here as a representative.

[0079] The CPU 601 starts monitoring the state of the image forming apparatus 100 in S1001. Here, it monitors whether the main switch 410, which is a trigger for the image forming apparatus 100 to transition to the power-off state, is off, or whether the image reading unit 901, the image generation unit 902, and each unit of the image forming apparatus 100, which are triggers for the image forming apparatus 100 to transition to the power-saving state, have not operated for a predetermined time or a request for transition to the power-saving state has been input from the operation unit 40.

[0080] First, the CPU 601 monitors whether it has detected the turning off of the main switch 410 in S1002 (S1002). If it detects that the main switch 410 has been turned off (S1002 Yes), it proceeds to S1003. On the other hand, if the CPU 601 does not detect the turning off of the main switch 410 (S1002 No), it monitors whether a transition to the power-saving state is necessary (S1010). Here, as described above, a transition to the power-saving state is determined to be necessary when the image reading unit 901, the image generation unit 902, and each unit of the image forming apparatus 100 have not operated for a predetermined time or a request for transition to the power-saving state has been input from the operation unit 40.

[0081] When the CPU 601 determines that the image forming apparatus 100 needs to shift to the power saving state (S1010 Yes), it proceeds to S1003. When it determines that the shift to the power saving state is not necessary (S1010 No), it returns to S1002 to continue monitoring the state of the image forming apparatus 100. Next, in S1003, the CPU 601 determines whether the steering HP sensor 453 is ON. The steering HP sensor 453 detects that it is in the ON state when it is shielded by the sector gear 460 and in the OFF state when it is not shielded.

[0082] In S1003, when the CPU 601 detects that the steering HP sensor 453 is ON (S1003 Yes), it starts driving the steering control stepping motor 452 in the CCW direction (counterclockwise) (S1004).

[0083] And the driving continues until the steering HP sensor 453 turns OFF. In S1005, when the CPU 601 detects that the steering HP sensor 453 has turned OFF (S1005 Yes), it stops the steering control stepping motor 452 (S1006). And the stop position is set as the reference position. In this embodiment, the steering control stepping motor 452 is stopped based on the OFF of the steering HP sensor 453, but it may also be stopped after a predetermined time after detecting the OFF of the steering HP sensor 453. That is, the position where the steering roller 501a is moved may be a position where the steering roller 501a has moved a predetermined distance from the position where the steering HP sensor 453 detected the OFF.

[0084] On the other hand, in S1003, when the CPU 601 detects that the steering HP sensor 453 is OFF (S1003 No), it starts driving the steering control stepping motor 452 in the CW direction (clockwise) (S1020). And in S1021, the CPU 601 continues the driving until the steering HP sensor 453 turns ON.

[0085] When the CPU 601 detects that the steering HP sensor 453 is ON in S1021 (S1021 Yes), it stops the steering control stepping motor 452 (S1022). After the CPU 601 detects the stop of the steering control stepping motor 452, if a predetermined time (the time until the vibration at the time of motor stop stabilizes) has not elapsed (S1023 No), it waits until the predetermined time elapses.

[0086] Next, after the predetermined time has elapsed in S1023 (S1023 Yes), the CPU 601 drives the steering control stepping motor 452 in the CCW direction (counterclockwise) (S1004). Then, in S1005, the CPU 601 continues the drive until the steering HP sensor 453 turns OFF. When the CPU 601 detects that the steering HP sensor 453 is OFF (S1005 Yes), it stops the steering control stepping motor 452 (S1006). Then, the stop position is set as the reference position. And the CPU 601 shifts the image forming apparatus 100 to the power-off state or the power-saving state (S1007).

[0087] Thus, in this embodiment, when the image forming apparatus 100 shifts to the power-off state (main switch 410 off) or to the power-saving state, the reference position of the steering roller 501a (the position where the axis of the steering roller 501a is substantially parallel to the axes of the other first belt suspension rollers 501b to 501d) is moved, making it possible to easily replace the belt. In this embodiment, control is performed to move the steering roller 501a to the reference position when the image forming apparatus 100 shifts to the power-off state or to the power-saving state, but the present invention is not limited to this. For example, a configuration may be adopted in which control is performed to move the steering roller 501a to the reference position only when shifting to the power-off state. Also, a configuration may be adopted in which control is performed to move the steering roller 501a to the reference position only when shifting to the power-saving state. Further, when the image forming apparatus 100 shifts from the power-saving state to the power-off state, a configuration may be adopted in which control is performed to move the steering roller 501a to the reference position at both the timing before shifting to the power-saving state and the timing before shifting to the power-off state. Also, when shifting to the power-off state or to the power-saving state, and when the steering roller 501a stops operating in a state inclined with respect to the reference position, a configuration may be adopted in which control is performed to move the steering roller 501a to the reference position. That is, when the steering roller 501a stops operating at the reference position when shifting to the power-off state or to the power-saving state, the above-described control does not have to be performed.

[0088] <Sequence when main switch is on> Next, the sequence when the main switch 410 in this embodiment is turned on will be described with reference to FIG. 11. Since the control of the first unit 501U and the second unit 502U is substantially the same, the first unit 501U will be described here as a representative.

[0089] The CPU 601 monitors the state of the main switch 410 in S2001. If the main switch 410 is not turned on (S2002N), it waits until the main switch 410 is turned on. When the main switch 410 is turned on (S2002Y), the CPU 601 acquires the detection result of the sensor unit 390 in S2003.

[0090] Also, the CPU 601 drives the belt drive motor 511 (S2004) to rotate the first belt 501. Then, the CPU 601 drives the stepping motor 452 based on the detection result of the sensor unit 390 acquired in S2003 to execute steering control (S2005). Details of the steering control are the same as the above-described control, so the description is omitted.

[0091] After that, the CPU 601 determines whether or not a predetermined time has elapsed since the start of the steering control (S2006). When the predetermined time has elapsed (S2006Y), the CPU 601 stops the stepping motor 452 (S2007) and stops the belt drive motor 511 (S2008).

[0092] In this way, the CPU 601 executes the steering control of the steering roller 501a even when the main switch 410 is turned on and the image forming apparatus 100 shifts to the standby state (at the time of starting the image forming apparatus). This is because the position of the first belt 501 in the width direction may change due to replacement work or the like in the power-off state of the image forming apparatus. Even when the first belt 501 is not replaced, by performing control to return the steering roller 501a to the reference position before shifting to the power-off state, there is a possibility that the angle of the steering roller 501a is deviated with respect to the position of the first belt 501.

[0093] Therefore, by executing the steering control when the image forming apparatus 100 is started up, it is possible to suppress the first belt 501 or the second belt 502 from moving too close to the ends of the steering rollers 501a and 502a. Also, by executing the steering control when the image forming apparatus 100 is started up, it is possible to set the angles of the steering rollers 501a and 502a to be suitable for the positions of the first belt 501 or the second belt 502. Incidentally, the predetermined time in S2006 described above may be set to a time that can return the angles of the steering rollers 501a and 502a to be suitable for the positions of the first belt 501 or the second belt 502 even when the amount by which the position of the first belt 501 or the second belt 502 deviates from the steering rollers 501a and 502a is at its maximum.

[0094] For example, when the main switch 410 of the image forming apparatus 100 is turned off while the first belt 501 is closer to the back side than the center of the image forming apparatus 100, the steering roller 501a returns to the reference position by the above-described control. However, depending on the rotation stop timing of the first belt 501, the position of the first belt 501 in the rotational axis direction of the steering roller 501a and the angle of the steering roller 501a may deviate. However, by executing the steering control when the main switch 410 is turned on as described above, even if the position of the first belt 501 is deviated to the back side from the center, the steering roller 501a is swung to a position where it returns the first belt 501 to the center based on the detection result of the sensor unit 390. Thereby, it is possible to suppress the angle of the steering roller 501a and the position of the first belt 501 from deviating, and to suppress the first belt 501 from moving too close.

[0095] When performing steering control in response to the main switch 410 being turned on as described above, since the first belt suspension roller 501e and the second belt suspension roller 502e are rotating, the first belt 501 and the second belt 502 also rotate. At this time, it may be determined by sensors (not shown) provided upstream and downstream of the cooling nip portion T4 in the sheet conveyance direction whether a sheet is being pinched by the cooling nip portion T4. In this case, when the sheet is in a state of being pinched by the cooling nip portion T4, a display may be made to the user to remove the sheet. Thereby, even when the power is turned on with the sheet left in the cooling nip portion T4 due to conveyance abnormality or the like, the operation of the cooling device 50 can be normally started by removing the sheet. Incidentally, the predetermined time of S2006 described above may be set to a time during which it can be determined by a sensor (not shown) whether a sheet is being pinched by the cooling nip portion T4.

[0096] Further, in the above-described embodiment, an example in which steering control is executed when the main switch 410 is turned on is shown, but a configuration in which steering control is executed when shifting from the power saving state to the standby state may also be used. In this case, even if control is performed to return the steering roller 501a to the reference position before shifting to the power saving state, the positional deviation between the steering roller 501a and the first belt 501 can be eliminated.

[0097] Incidentally, in the above-described embodiment, the steering roller 501a is moved to a position where the axis of the steering roller 501a is substantially parallel to the axes of the other first belt suspension rollers 501b to 501d before shifting to the power off state or the power saving state. However, when an operator receives an instruction to replace the first belt 501 (second belt 502) from the operation panel 40 or the like, a configuration in which the steering roller 501a is moved to the reference position may also be used. That is, a configuration in which the steering roller 501a is moved to a position where the axis of the steering roller 501a is substantially parallel to the axes of the other first belt suspension rollers 501b to 501d by an input from the operation panel 40 may also be used. Thereby, the workability at the time of replacing the first belt 501 (second belt 502) can also be improved.

[0098] Also, in this embodiment, the steering control stepping motor 452 is stopped based on the OFF state of the steering HP sensor 453. However, after detecting the OFF state of the steering HP sensor 453, it may be stopped after a predetermined time. By controlling in this way, it is possible to reliably move the steering roller to the reference position regardless of the displacement amount of the steering roller at the start of control.

[0099] As in this embodiment, before shifting to the power-off state or power-saving state of the image forming apparatus 100, by moving the steering roller 501a to the reference position, it is possible to suppress the steering roller 501a from stopping in an inclined state when replacing the first belt 501. As a result, since the load when pulling out the first belt 501 with respect to the inclined steering roller 501a is reduced, it is possible to provide an image forming apparatus in which the belt can be easily replaced.

[0100] In the above-described embodiment, the case where the recording material cooling device 50 is provided in the image forming apparatus 100 is shown as an example (see FIG. 1), but it is not limited thereto. For example, the recording material cooling device 50 may be provided outside the housing of the image forming apparatus 100 as an option device. That is, the cooling device 50 may be supported by an independent frame different from the frame of the image forming apparatus 100. FIG. 12 shows a configuration in which the recording material cooling device 50 is provided outside the image forming apparatus 100. In this embodiment, when the external cooling device 101 is connected to the image forming apparatus 100 as an external device as shown in FIG. 12, the image forming apparatus 100 and the external cooling device 101 together are referred to as an image forming apparatus. That is, in this embodiment, the entire apparatus involved from when the sheet on which the image is formed is fed until it is discharged to the outside of the apparatus is referred to as an image forming apparatus. Also, when connecting a sheet process that performs binding processing, perforating processing, etc. on the sheet to the downstream side of the external cooling device 101, a configuration including the image forming apparatus 100, the external cooling device 101, and the sheet processing apparatus is referred to as an image forming apparatus that forms an image on the sheet.

[0101] The external cooling device 101 shown in FIG. 12 is configured to be connectable to the image forming apparatus 100 as one of the peripheral devices (referred to as option units, etc.) that can be retrofitted to expand the functions of the image forming apparatus 100. The external cooling device 101 is disposed to cool the recording material S discharged from the image forming apparatus 100 and lower the temperature of the recording material S that has passed through the fixing device 30 to a predetermined temperature or lower. The external cooling device 101 has the recording material cooling device 50 described above for cooling the recording material S. Since each unit of the image forming apparatus 100 has the same configuration as that shown in FIG. 1 described above, the same reference numerals are given and the description thereof is omitted.

[0102] The recording material S cooled by the external cooling device 101 is discharged from the external cooling device 101 by the discharge roller 85 and stacked on the discharge tray 120. The discharge tray 120 is detachably provided with respect to the external cooling device 101 and the image forming apparatus 100. That is, the discharge tray 120 is mounted on the image forming apparatus 100 when the external cooling device 101 is not connected to the image forming apparatus 100 (see FIG. 1). Then, when the external cooling device 101 is connected to the image forming apparatus 100, it is removed from the image forming apparatus 100 by an operator and replaced with the external cooling device 101. Note that a plurality of external cooling devices 101 may be connected as peripheral devices. The operator can easily improve the cooling ability of the recording material S for the existing image forming apparatus 100 by increasing the number of the connected external cooling devices 101.

[0103] Note that a configuration may be adopted in which the external cooling device 101 is further connected to the image forming apparatus 100 having the recording material cooling device 50 inside. Also, a configuration may be adopted in which another sheet processing device such as a curl correction device is interposed between the image forming apparatus 100 and the external cooling device 101, or a configuration may be adopted in which a sheet processing device is further connected to the downstream side in the sheet conveyance direction with respect to the external cooling device 101.

[0104] When this embodiment is applied to such an image forming apparatus, when shifting to the power-off state or the power-saving state of the external cooling device 101 having the recording material cooling device 50, the steering rollers 501a and 502a are moved to the reference position. In this way, by moving the steering rollers 501a and 502a to the reference position according to the power state of the device having the recording material cooling device 50, the replaceability of the first belt 501 or the second belt 502 can be improved. Further, when power is supplied to the external cooling device 101 via the image forming apparatus 100, the external cooling device 101 shifts to the power-off state in conjunction with the OFF (power-off) of the main switch 410 of the image forming apparatus 100. Even in this configuration, before shifting to the power-off state or the power-saving state of the image forming apparatus 100 as described above, the steering rollers 501a and 502a are moved to the reference position. In this way, by moving the steering rollers 501a and 502a to the reference position according to the state of the image forming apparatus 100, the replaceability of the first belt 501 or the second belt 502 provided in the cooling device 50 of the external cooling device 101 can be improved.

[0105] Also, in the above-described embodiment, the same control is performed on both the steering rollers 501a and 502a of the first unit 501U and the second unit 502U, but a configuration in which this control is executed only for one of the units may be used. For example, a configuration in which only the first unit 501U, which has the heat sink 503 and thus has a limited moving distance of the steering roller 501a toward the inner peripheral side, performs the above-described control may be used.

[0106] Also, in the above-described embodiment, a configuration in which the recording material is sandwiched and conveyed by the first belt 501 and the second belt 502 has been described, but the second belt 502 may be replaced with a plurality of conveying rollers. That is, a configuration in which a conveying nip is formed by the first belt 501 in contact with the inner peripheral surface of the heat sink 503 and a conveying unit having a plurality of conveying rollers or the like, and the recording material is sandwiched and conveyed may be used.

[0107] In the above-described embodiment, the steering rollers 501a and 502a are configured to swing about the central portion in the axial direction of the rotation axis. However, a configuration may be adopted in which the rollers swing about the rear end or the front end in the axial direction of the rotation axis. Even with such a configuration, depending on the swing angle of the rollers when the power is off, it may become difficult to replace the first belt 501 or the second belt 502. For example, in a configuration in which the rear ends of the steering rollers 501a and 502a are the swing centers, when the steering roller 501a swings such that the front end of the steering roller 501a moves away from the heat sink 513, it becomes difficult to pull out the first belt 501 from the front side. Therefore, even in a configuration in which the rollers swing about the end portion in the axial direction of the rotation axis, by returning the steering rollers 501a and 502a to an angle parallel to the other rollers before shifting to the power-off state as in the present embodiment, the workability of replacing the first belt 501 or the second belt 502 can be improved.

Explanation of Signs

[0108] 100 Image forming apparatus 500 Fixing device 50 Cooling device 501 First belt 502 Second belt 503 Heat sink 501e, 502e Driving roller 501a, 502a Steering roller 509a, 509b Pressing roller 513 Heat sink cooling fan

Claims

1. An image forming apparatus having an image forming unit for forming a toner image on a recording material and a fixing device for fixing the toner image on the recording material, and being capable of transitioning between a power-off state and a standby state in which image formation by the image forming unit is possible, a belt, a conveying unit that forms a conveying nip together with the belt and sandwiches and conveys the recording material that has passed through the fixing device with the nip, a heat sink that contacts the inner peripheral surface of the belt, a first roller and a second roller that suspend the belt, a belt position detection unit that detects the position of the belt in the width direction that is orthogonal to the thickness direction of the belt and the conveying direction of the recording material sandwiched in the nip, a steering unit that swings the first roller with respect to the second roller in accordance with the detection result of the position detection unit so as to move the belt in the width direction with respect to the first roller, a switch that can be switched on and off by a user, and comprising when the switch is switched from ON to OFF, the steering unit makes the rotation axis of the first roller substantially parallel to the rotation axis of the second roller, and after the rotation axis of the first roller becomes substantially parallel to the rotation axis of the second roller, the image forming apparatus transitions to the power-off state An image forming apparatus characterized by this.

2. The steering unit swings the first roller with the central portion of the first roller in the width direction as a swing center, The image forming apparatus according to claim 1, characterized by this.

3. further comprising the first roller, the second roller, and a frame that supports the heat sink, The second roller is rotatably fixed to the frame, The image forming apparatus according to claim 1 or 2, characterized by this.

4. The state where the first roller is substantially parallel to the second roller means that the inclination of the first roller with respect to the second roller is within ±0.5°. The image forming apparatus according to any one of claims 1 to 3, characterized in that.

5. It has a steering position detection unit that detects the displacement amount of the rotation axis of the first roller with respect to the state where the rotation axis of the first roller is substantially parallel to the rotation axis of the second roller, When the image forming apparatus shifts to the power-off state, the displacement amount detected by the steering position detection unit becomes 0. The image forming apparatus according to any one of claims 1 to 4, characterized in that.

6. The conveyance unit, Another belt that sandwiches and conveys the recording material together with the belt, A third roller that suspends the other belt, A fourth roller that suspends the other belt together with the third roller, Another belt position detection unit that detects the position of the other belt in the axial direction of the rotation axis of the third roller, Another steering unit that changes the angle of the third roller with respect to the fourth roller according to the detection result of the other belt position detection unit and moves the other belt in the rotation axis direction of the third roller with respect to the third roller, and has, When the image forming apparatus shifts to the power-off state, the other steering unit makes the rotation axis of the third roller substantially parallel to the rotation axis of the fourth roller The image forming apparatus according to any one of claims 1 to 5, characterized in that.

7. The image forming apparatus can transition to a power-saving state with lower power consumption than the standby state, When the image forming apparatus shifts to the power saving state, the steering unit makes the rotation axis of the first roller substantially parallel to the rotation axis of the second roller. The image forming apparatus according to any one of claims 1 to 6, characterized in that.

8. When the image forming unit has stopped operating for a predetermined time, the steering unit makes the rotation axis of the first roller substantially parallel to the rotation axis of the second roller. After the rotation axis of the first roller becomes substantially parallel to the rotation axis of the second roller, the image forming apparatus transitions to the power saving state. The image forming apparatus according to claim 7, characterized in that.

9. An image forming apparatus having an image forming unit that forms a toner image on a recording material and a fixing device that fixes the toner image on the recording material, and capable of transitioning between a standby state in which image formation by the image forming unit is possible and a power saving state in which power consumption is lower than in the standby state. A belt A conveying unit that forms a conveying nip together with the belt and sandwiches and conveys the recording material that has passed through the fixing device at the nip. A heat sink that contacts the inner peripheral surface of the belt. A first roller and a second roller that suspend the belt. A belt position detection unit that detects the position of the belt in the width direction that is orthogonal to the thickness direction of the belt and the conveying direction of the recording material sandwiched at the nip. A steering unit that swings the first roller with respect to the second roller according to the detection result of the position detection unit so as to move the belt in the width direction with respect to the first roller. An operation unit operable by a user, and is provided with. When a transition instruction to the power saving state is input from the user via the operation unit, the steering unit makes the rotation axis of the first roller substantially parallel to the rotation axis of the second roller. After the rotation axis of the first roller becomes substantially parallel to the rotation axis of the second roller, the image forming apparatus transitions to the power saving state. An image forming apparatus characterized by the above.

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