Patent Application
20200301360
Embodiments described herein relate generally to a heating device and an image processing apparatus.
Image processing apparatuses such as image forming apparatuses include heating devices such as fixing devices. The fixing devices heat and pressurize toner images transferred to paper to fix the toner images to the paper. Sheet passing regions of the fixing devices are heated at predetermined fixing temperatures. On the other hand, temperatures of sheet non-passing regions of the fixing devices may become high because heat is not transferred to the paper. Heating devices capable of efficiently cooling sheet non-passing regions are desirable.
In general, according to an embodiment, a heating device includes a rotator, a fan, an introduction duct, a cooling duct, and a movement mechanism. The rotator has, inside thereof, a heater configured to generate heat for fixing a toner image. The fan is configured to generate an airflow towards a surface of the rotator. The introduction duct is positioned with respect to the fan and shaped such that the airflow generated by the fan is directed towards and is incident on a first end portion of the rotator in an axial direction of the rotator. The cooling duct extends between the introduction duct and a first end of the rotator in the axial direction, and faces the first end portion of the rotator. The cooling duct includes a plurality of duct portions extending along the rotational axis of the rotator. The movement mechanism is configured to move the fan, the introduction duct, and at least one of the duct portions of the cooling duct along the rotational axis of the rotator.
Hereinafter, a heating device and an image processing apparatus according to an embodiment will be described with reference to the drawings.
The image processing apparatus according to the embodiment is an image forming apparatus 1. The image forming apparatus 1 performs a process of forming an image on a sheet (paper) S.
The image forming apparatus 1 includes a housing 10, a scanner unit 2, an image forming unit 3, a sheet supply unit 4, a transport unit 5, a discharge tray 7, a reversing unit 9, a control panel 8, and a control unit 6.
The housing 10 forms the outer shape of the image forming apparatus 1.
The scanner unit 2 obtains image information of a copy target based on brightness and darkness of light to generate an image signal. The scanner unit 2 outputs the generated image signal to the image forming unit 3.
The image forming unit 3 forms an output image (hereinafter referred to as a toner image) using a recording agent such as toner based on the image signal received from the scanner unit 2 or an image signal received from the outside. The image forming unit 3 transfers the toner image to the surface of the sheet S. The image forming unit 3 heats and pressurizes the toner image on the surface of the sheet S to fix the toner image to the sheet S. The details of the image forming unit 3 will be described below.
The sheet supply unit 4 supplies the sheets S to the transport unit 5 one by one at a timing at which the image forming unit 3 forms the toner image. The sheet supply unit 4 includes a sheet accommodation unit 20 and a pickup roller 21.
The sheet accommodation unit 20 accommodates a predetermined kind of sheet S of a predetermined size.
The pickup roller 21 picks up the sheets S one by one from the sheet accommodation unit 20. The pickup roller 21 supplies the picked-up sheet S to the transport unit 5.
The transport unit 5 transports the sheet S supplied from the sheet supply unit 4 to the image forming unit 3. The transport unit 5 includes transport rollers 23 and the register rollers 24.
The transport rollers 23 transport the sheet S supplied from the pickup roller 21 to the register rollers 24. The transport rollers 23 butts a leading end of the sheet S in a transport direction to a nip N of the register rollers 24.
The register rollers 24 arrange the position of the leading end of the sheet S in the transport direction by curving the sheet S at the nip N. The register rollers 24 transport the sheet S at a timing at which the image forming unit 3 transfers the toner image to the sheet S.
The image forming unit 3 will be described below.
The image forming unit 3 includes a plurality of image forming sections 25, a laser scanning unit 26, an intermediate transfer belt 27, a transfer unit 28, and a fixing device 30.
The image forming section 25 includes a photoconductive drum 25d. The image forming section 25 forms the toner image in accordance with an image signal from the scanner unit 2 or the outside on the photoconductive drum 25d. The plurality of image forming sections 25Y, 25M, 25C, and 25K form toner images using yellow, magenta, cyan, and black toner, respectively.
A charging unit, a developing unit, and the like are disposed around the photoconductive drum 25d. The charging unit charges the surface of the photoconductive drum 25d. The developing unit accommodates a developer including yellow, magenta, cyan, and black toner. The developing unit develops an electrostatic latent image on the photoconductive drum 25d. Then, the toner image is formed using the toner of each color on the photoconductive drum 25d.
The laser scanning unit 26 scans the charged photoconductive drum 25d with a laser beam L to expose the photoconductive drum 25d. The laser scanning unit 26 exposes the photoconductive drums 25d of the image forming sections 25Y, 25M, 25C, and 25K of each color to laser beams LY, LM, LC, and LK of each light ray. In this manner, the laser scanning unit 26 forms the electrostatic latent images on the photoconductive drums 25d.
The toner image on the surface of the photoconductive drums 25d is primarily transferred to the intermediate transfer belt 27.
The transfer unit 28 transfers the toner image primarily transferred onto the intermediate transfer belt 27 onto the surface of the sheet S at a secondary transfer position.
The fixing device 30 heats and pressurizes the toner images transferred to the sheet S to fix the toner images to the sheet S. The details of the fixing device 30 will be described below.
The reversing unit 9 reverses the sheet S to form an image on the back surface of the sheet S. The reversing unit 9 reverses the front and back of the sheet S discharged from the fixing device 30 by switch back. The reversing unit 9 transports the reversed sheet S toward the register rollers 24.
The discharge tray 7 loads the sheet S discharged after the image is formed.
The control panel 8 is a part of an input unit with which information for an operator to operate the image forming apparatus 1 is input. The control panel 8 includes a touch panel and various hard keys.
The control unit 6 controls each unit of the image forming apparatus 1. The details of the control unit 6 will be described below.
The CPU 91 functions as the control unit 6 by executing a program stored in the memory 92 and the auxiliary storage device 93. The control unit 6 controls an operation of each functional unit of the image forming apparatus 1.
The auxiliary storage device 93 is configured as a storage device such as a magnetic hard disk device or a semiconductor storage device. The auxiliary storage device 93 stores information.
The communication unit 90 includes a communication interface for connecting the image forming apparatus to an external apparatus. The communication unit 90 communicates with an external apparatus via a communication interface.
The fixing device 30 will be described below.
The pressure roller 30p can come into contact with the heating roller 30h and can be separated from the heating roller 30h. The pressure roller 30p includes an axial member 31 and a surface layer member 32.
The axial member 31 is formed of a metal material or the like. The axial member 31 is rotatably driven by a motor (not illustrated).
The surface layer member 32 is formed of a rubber material or the like. The outermost circumference of the surface layer member 32 is coated with a surface protection layer such as PFA.
The heating roller 30h is disposed side by side with the pressure roller 30p. The heating roller 30h includes a heater (heat source) 34, a heater holding member 35, a support member 36, a fixing belt (rotator) 38, and a temperature sensor 39. The heater 34, the heater holding member 35, and the support member 36 stretch in a direction of a rotation axis C of the fixing belt 38 and are disposed inside the fixing belt 38.
The heater 34 is formed by stacking heating resistance layers on a substrate. The substrate is formed of a ceramic material or the like. The heating resistance layer is formed of a material generating heat by conduction. A protective layer is formed on the surface of the heater 34 which is in contact with the fixing belt 38. The heater 34 is disposed inside the fixing belt 38 at a position closest to the pressure roller 30p.
The heater holding member 35 is formed of a resin material with a thermal resisting property or the like. The heater holding member 35 is disposed on a side opposite to the pressure roller 30p with the heater 34 therebetween to hold the heater 34.
The support member 36 is formed of a metal material or the like. The support member 36 is disposed on a side opposite to the pressure roller 30p with the heater holding member 35 therebetween. Both ends of the support member 36 in the longitudinal direction extend outwards from both ends of the fixing belt 38 in the direction of the rotation axis C. Both ends of the support member 36 are fixed to the housing 10 of the image forming apparatus 1. In this manner, the support member 36 supports the constituent members of the heating roller 30h.
The fixing belt 38 is a cylindrical endless belt. The fixing belt 38 is formed by stacking a base layer, an elastic layer, and a surface release layer from the inner circumference side to the outer circumference side. The base layer is formed of a metal material or the like. The elastic layer is formed of a rubber material or the like. The surface release layer is formed of PFA or the like. The fixing belt 38 may be a film-like member.
The temperature sensor 39 comes into contact with the inner circumferential surface of the fixing belt 38. The temperature sensor 39 is used to detect temperature of the fixing belt 38. The temperature sensor 39 outputs a signal corresponding to the temperature of the fixing belt 38 to the control unit 6.
When the pressure roller 30p comes into contact with the heating roller 30h, the nip N is formed between the pressure roller 30p and the fixing belt 38. When the pressure roller 30p is rotatably driven, the fixing belt 38 is driven to rotate about the rotation axis C by a frictional force. When the sheet S is passed through the nip N, the toner images transferred to the sheet S are heated and pressurized. Thus, the fixing device 30 fixes the toner images to the sheet S. Since the heater 34 is disposed inside the fixing belt 38 in the nip N, the heater 34 substantially forms the nip N. When the heater 34 heats the sheet S while forming the nip N, the fixing device 30 with good responsiveness at the time of conduction is formed.
As illustrated in
The cooling device 40 will be described below.
In the present specification, X direction, Y direction, and Z direction are defined as follows. X direction is a direction in which the cooling device 40 and the fixing belt 38 which is a cooling target are arranged. +X direction is a direction oriented from the cooling device 40 to the fixing belt 38. Y direction (a rotation axis direction) is a direction of the rotation axis C of the fixing belt 38. +Y direction (a first direction) is a direction oriented from the left end (a second end) of the fixing belt 38 to the right end (a first end) of the fixing belt 38 in
The cooling device 40 includes a first cooling device 40a, a second cooling device 40b, and a movement mechanism 41.
The first cooling device 40a includes a first fan 51a, a first connection duct 52a, a first introduction duct 54a, and a first cooling duct 60a.
The first fan 51a generates a first cooling wind for cooling the fixing belt 38. The first fan 51a is disposed so that the first cooling wind is directed in +X direction.
The first connection duct 52a is disposed downstream from the first fan 51a in a circulation direction of the first cooling wind (hereinafter simply referred to as a downstream side). The first connection duct 52a is connected in +X direction of the first fan 51a. The cross-sectional shape orthogonal to a passage center axis of the first connection duct 52a is rectangular. The passage center axis of the first connection duct 52a is disposed in parallel to X direction. The first connection duct 52a connects the first fan 51a to the first introduction duct 54a.
The first introduction duct 54a is disposed downstream from the first connection duct 52a. The cross-sectional shape orthogonal to a passage center axis 55 of the first introduction duct 54a is rectangular. The first introduction duct 54a stretches in +Y direction as approaching the rotation axis C of the fixing belt 38 (being oriented in +X direction). The first introduction duct 54a stretches in +X direction and +Y direction from the end of the first connection duct 52a in +X direction. An angle of the first introduction duct 54a with respect to −Y direction of the passage center axis 55 is θ1. An angle of −Y direction of the first introduction duct 54a with respect to −Y direction of a wall surface 56 is θ2. The angles θ1 and θ2 are less than 90 degrees. The angles θ1 and θ2 are preferably equal to or less than 40 degrees.
The first cooling duct 60a is disposed downstream from the first introduction duct 54a. The cross-sectional shape orthogonal to the passage center axis of the first cooling duct 60a is a U shape open in +X direction. The first cooling duct 60a stretches in +Y direction along the outer circumferential surface of the fixing belt 38 from the ends of the first introduction duct 54a in +X direction and +Y direction. A first exhaust port 68a is open at the front end of the first cooling duct 60a in +Y direction. The position of the first exhaust port 68a in Y direction is the same as the position of the end of the fixing belt 38 in +Y direction. A first cooling port 58a of the first cooling duct 60a is open along the outer circumferential surface of the fixing belt 38.
The first cooling duct 60a is formed by combining a plurality of partial ducts 61, 62, 63, and 64 in Y direction. The outer shapes of the plurality of partial ducts 61 to 64 on the XZ cross sections increase in +Y direction. The plurality of partial ducts 61 to 64 can overlap each other when viewed in X direction and Z direction. A relative position of the partial duct 64 disposed at the front end in +Y direction with respect to the fixing belt 38 in Y direction is fixed. The other partial ducts 61 to 63 can be moved in Y direction. Thus, the first cooling duct 60a is formed to be expandable and contractible in Y direction.
A first stopper 62r is provided at the end of the partial duct 62 in −Y direction. The first stopper 62r protrudes from the end of the partial duct 62 in −Y direction to the inside of the partial duct 62. A second stopper 62s and a third stopper 62t are provided at the end of the partial duct 62 in +Y direction. The second stopper 62s protrudes from the end of the partial duct 62 in +Y direction to the outside of the partial duct 62. The third stopper 62t protrudes from the end of the partial duct 62 in +Y direction to the inside of the partial duct 62. The same applies to the other partial ducts 61, 63, and 64.
When the first cooling duct 60a stretches in Y direction, the first stopper 62r of the partial duct 62 comes into contact with the second stopper 61s of the partial duct 61. In addition, the second stopper 62s of the partial duct 62 comes into contact with the first stopper 63r of the partial duct 63. The same applies to the other partial ducts 61, 63, and 64. Thus, when the first cooling duct 60a stretches in Y direction, separation of the plurality of partial ducts 61 to 64 is prevented. In addition, the upper limit of an expansion and contraction range of the first cooling duct 60a is regulated. Leakage of the first cooling wind from connection portions of the plurality of partial ducts 61 to 64 is suppressed.
When the first cooling duct 60a contacts in Y direction, the third stopper 62t of the partial duct 62 comes into contact with the second stopper 61s of the partial duct 61. The same applies to the other partial ducts 61, 63, and 64. Thus, the lower limit of the expansion and contraction range of the first cooling duct 60a is regulated. Leakage of the first cooling wind from connection portions of the plurality of partial ducts 61 to 64 is suppressed.
The first connection duct 52a, the first introduction duct 54a, and the partial duct 61 of the first cooling duct 60a are integrally formed. These members may be connected after the members are separately formed. The first fan 51a, the first connection duct 52a, the first introduction duct 54a, and the partial duct 61 of the first cooling duct 60a can be moved in Y direction. These members form a first movement portion 50a.
As illustrated in
The second cooling device 40b includes a second fan 51b, a second connection duct 52b, a second introduction duct 54b, and a second cooling duct 60b. The configuration of these members is the same as that of the first cooling device 40a. The second fan 51b, the second connection duct 52b, the second introduction duct 54b, and the partial duct 61 of the second cooling duct 60b can be moved in Y direction. These members form a second movement portion 50b.
The movement mechanism 41 moves the first movement portion 50a and the second movement portion 50b in Y direction. The movement mechanism 41 moves the first movement portion 50a and the second movement portion 50b to be plane-symmetric with respect to the symmetric plane F. The movement mechanism 41 includes a first rack 42a, a second rack 42b, a pinion gear 43, a motor 45, a first wheel 47a, a second wheel 47b, and a rail 48.
The first rack 42a is connected to the first movement portion 50a to stretch in −Y direction. The second rack 42b is connected to the second movement portion 50b to stretch in +Y direction. The pinion gear 43 is disposed between the first rack 42a and the second rack 42b in Z direction to engage with both the first rack 42a and the second rack 42b. The motor 45 rotates the pinion gear 43. For example, the motor 45 is a stepping motor. The first wheel 47a is mounted in −Z direction of the first movement portion 50a. The second wheel 47b is mounted in −Z direction of the second movement portion 50b. The rail 48 is disposed in −Z direction of the first wheel 47a and the second wheel 47b to guide rolling of the first wheel 47a and the second wheel 47b.
When the pinion gear 43 is rotated by the motor 45, the first rack 42a and the second rack 42b are moved in Y direction to be plane-symmetric with respect to the symmetric plane F. Thus, the first movement portion 50a and the second movement portion 50b move in Y direction to be plane-symmetric with respect to the symmetric plane F. When the first movement portion 50a moves in Y direction, the partial ducts 62 and 63 of the first cooling duct 60a move together in Y direction. The same applies to the second movement portion 50b.
As illustrated in
The control unit 6 controls an operation of the fixing device 30. The control unit 6 controls operations of the first fan 51a, the second fan 51b, and the movement mechanism 41 of the cooling device 40.
As described above, the fixing device 30 heats the toner images of the sheet S passing through the nip N to fix the toner images to the sheet S. In a printing state of the image forming apparatus 1, the control unit 6 maintains the temperature of the fixing belt 38 at a predetermined fixing temperature. In a printing standby state of the image forming apparatus 1, the control unit 6 maintains the temperature of the fixing belt 38 at a standby temperature lower than the fixing temperature.
The sheet S passes through the middle of the nip N in Y direction. The sheet S deprives the fixing belt 38 of heat while being passed through the nip N. A sheet passing region of the fixing belt 38 is maintained at the fixing temperature while being deprived of the heat by the sheet S. Since a sheet non-passing region of the fixing belt 38 is not deprived of the heat by the sheet S, the temperature of the region becomes high. The control unit 6 controls the cooling device 40 to cool the sheet non-passing region of the fixing belt 38. The control unit 6 causes the cooling device 40 to operate simultaneously with the start of a printing job.
The control unit 6 drives the first fan 51a to send off a first cooling wind W from the first fan 51a. The first cooling wind W flows in the first introduction duct 54a through the first connection duct 52a. The first introduction duct 54a stretches in +Y direction as approaching the rotation axis C of the fixing belt 38 (being oriented in +X direction). Therefore, the first cooling wind W flowing out from the first introduction duct 54a flows in +Y direction along the outer circumferential surface of the fixing belt 38. The first cooling wind W cools a sheet non-passing region A2 of the fixing belt 38 when the first cooling wind W is in contact with the outer circumferential surface of the fixing belt 38 in the first cooling port 58a.
As described above, the first introduction duct 54a stretches in +Y direction as approaching the rotation axis C of the fixing belt 38 (being oriented in +X direction). Therefore, the first cooling wind W flowing out from the first introduction duct 54a is less likely to flow in −Y direction around the end 59a of the first cooling port 58a in −Y direction. A sheet passing region A1 of the fixing belt 38 is less likely to be cooled by the first cooling wind W. The temperature of the sheet passing region A1 of the fixing belt 38 is maintained at the fixing temperature even when output of the heater 34 is raised. As described above, the sheet non-passing region A2 of the fixing belt 38 is efficiently cooled.
The control unit 6 includes a movement control unit. The movement control unit moves the first movement portion 50a so that the end 59a of the first cooling port 58a in −Y direction is disposed at a position away by a predetermined distance D in +Y direction from the end of the sheet S subjected to the fixing process in +Y direction. For example, the predetermined distance D is equal to or greater than 2 mm and equal to or less than 3 mm. When the outer circumferential surface of the fixing belt 38 facing the first cooling port 58a is cooled by the first cooling wind W, the fixing belt 38 in the periphery of the first cooling port 58a is cooled by heat transmission. In the foregoing configuration, substantially the entire sheet non-passing region A2 is cooled while suppressing the cooling of the sheet passing region A1 of the fixing belt 38. Accordingly, the sheet non-passing region A2 of the fixing belt 38 can be efficiently cooled.
The control unit 6 includes a first operation control unit. The first operation control unit causes the cooling device 40 to operate when the width of the sheet S subjected to the fixing process in Y direction is less than a predetermined width. For example, the predetermined width is 150 mm. When the width of the sheet S in Y direction is large, most of the fixing belt 38 is deprived of heat by the sheet S, the temperature of the sheet non-passing region A2 of the fixing belt 38 is less likely to become. In this case, the control unit 6 does not cause the cooling device 40 to operate. Conversely, when the width of the sheet S in Y direction is less than the predetermined width, there is a possibility that the temperature of the sheet non-passing region A2 of the fixing belt 38 becomes high. In this case, the control unit 6 causes the cooling device 40 to operate. Thus, since the operation of the cooling device 40 is limited to a necessary case, power consumption of the cooling device 40 can be suppressed.
The control unit 6 includes a second operation control unit. The second operation control unit causes the cooling device 40 to operate when the number of sheets S continuously subjected to the fixing process is equal to or greater than a predetermined number. When the number of sheets S continuously subjected to the fixing process is small, a temperature difference is small between the sheet passing region A1 deprived of heat by the sheet S and the sheet non-passing region A2 not deprived of heat by the sheet S. That is, the temperature of the sheet non-passing region A2 of the fixing belt 38 is less likely to become high. In this case, the control unit 6 does not cause the cooling device 40 to operate. In contrast, when the number of sheets S continuously subjected to the fixing process is equal to or greater than the predetermined number, the temperature difference is large between the sheet passing region A1 and the sheet non-passing region A2. That is, there is a possibility that the temperature of the sheet non-passing region A2 of the fixing belt 38 becomes high. In this case, the control unit 6 causes the cooling device 40 to operate. Thus, since an operation of the cooling device 40 is limited to a necessary case, power consumption of the cooling device 40 can be suppressed.
The control unit 6 includes a third operation control unit. The third operation control unit causes the cooling device 40 to operate when the temperature of the end of the fixing belt 38 in Y direction is equal to or higher than a predetermined temperature. The temperature of the end of the fixing belt 38 in Y direction is detected by the end temperature sensor 39n (see
As described above, the fixing device 30 according to the embodiment includes the fixing belt 38, the first fan 51a, the first introduction duct 54a, the first cooling duct 60a, and the movement mechanism 41. The heater 34 is disposed inside the fixing belt 38. The first fan 51a generates the first cooling wind W for cooling the fixing belt 38. The first cooling wind W flows in from the end of the first introduction duct 54a on the side of the first fan 51a. The first introduction duct 54a stretches in +Y direction as approaching the rotation axis C of the fixing belt 38. The first cooling duct 60a stretches in +Y direction along the outer circumferential surface of the fixing belt 38 from the end of the first introduction duct 54a on the side of the fixing belt 38. The first exhaust port 68a is open to the front end of the first cooling duct 60a in +Y direction. The first cooling port 58a is opened to the first cooling duct 60a along the outer circumferential surface of the fixing belt 38. The movement mechanism 41 moves the first movement portion 50a including the first fan 51a, the first introduction duct 54a, and the partial duct 61 of the first cooling duct 60a in Y direction.
The first introduction duct 54a stretches in +Y direction as approaching the rotation axis C of the fixing belt 38. The first cooling wind W flowing from the first introduction duct 54a flows in +Y direction along the outer circumferential surface of the fixing belt 38. The first cooling wind W cools the sheet non-passing region A2 of the fixing belt 38 when the first cooling wind W is in contact with the outer circumferential surface of the fixing belt 38 in the first cooling port 58a. The first cooling wind W flowing from the first introduction duct 54a is less likely to flow in −Y direction around the end 59a of the first cooling port 58a in −Y direction. The sheet passing region A1 of the fixing belt 38 is less likely to be cooled by the first cooling wind W. As described above, the sheet non-passing region A2 of the fixing belt 38 is efficiently cooled. The first cooling wind W generated by the first fan 51a is used to cool the outer circumferential surface of the fixing belt 38 without reducing a passage and a flow rate. Accordingly, the sheet non-passing region A2 of the fixing belt 38 can be efficiently cooled.
The relative position of first exhaust port 68a with respect to the fixing belt 38 in Y direction is fixed. The first cooling duct 60a is formed to be expandable and contractible in Y direction.
In this configuration, the position of the first exhaust port 68a is not moved even when the first movement portion 50a is moved. Accordingly, an increase in the size of the fixing device 30 can be suppressed.
The first cooling duct 60a is formed by combining the plurality of partial ducts 61 to 64 in Y direction. The outer shapes of the plurality of partial ducts 61 to 64 on the XZ cross sections orthogonal to the rotation axis C increase in +Y direction.
Thus, the first cooling duct 60a is formed to be expandable and contractible. Since the outer shapes of the plurality of partial ducts 61 to 64 increase in +Y direction, passage resistance of the first cooling duct 60a decreases in +Y direction. Therefore, leakage of the first cooling wind W from a gap between the first cooling duct 60a and the fixing belt 38 is suppressed. Accordingly, the sheet non-passing region A2 of the fixing belt 38 is efficiently cooled.
The fixing device 30 includes the second fan 51b, the second introduction duct 54b, and the second cooling duct 60b. The second fan 51b generates a second cooling wind for cooling the fixing belt 38. The second cooling wind flows in from the end of the second introduction duct 54b on the side of the second fan 51b. The second introduction duct 54b stretches in −Y direction as approaching the fixing belt 38. The second cooling duct 60b stretches in −Y direction from the end of the second introduction duct 54b on the side of the fixing belt 38 along the outer circumference of the fixing belt 38. A second exhaust port 68b is open to the front end of the second cooling duct 60b in −Y direction. The second cooling port 58b is open to the second cooling duct 60b along the outer circumferential surface of the fixing belt 38. The movement mechanism 41 moves the second movement portion 50b including the second fan 51b, the second introduction duct 54b, and the partial duct 61 of the second cooling duct 60b in Y direction.
The first cooling device 40a including the first fan 51a, the first introduction duct 54a, and the first cooling duct 60a is disposed in +Y direction from a center of the fixing belt 38 in Y direction. The second cooling device 40b including the second fan 51b, the second introduction duct 54b, and the second cooling duct 60b is disposed in −Y direction from the center of the fixing belt 38 in Y direction.
In this configuration, the sheet non-passing regions A2 at both ends of the fixing belt 38 in Y direction are cooled when a middle portion of the fixing belt 38 in Y direction serves as the sheet passing region A1.
The movement mechanism 41 moves the first movement portion 50a and the second movement portion 50b to be plane-symmetric with respect to the plane F which is orthogonal to the rotation axis C and passes through the center of the fixing belt 38 in Y direction.
In this configuration, the sheet non-passing regions A2 at both ends of the fixing belt 38 in Y direction are evenly cooled.
The image forming apparatus 1 according to the embodiment includes the fixing device 30 and the control unit 6. The fixing device 30 performs a fixing process on an image on the sheet S. The control unit 6 controls the operations of the first fan 51a and the movement mechanism 41 of the fixing device 30.
In this configuration, since the sheet non-passing region A2 of the fixing belt 38 is efficiently cooled, power consumption of the image forming apparatus 1 is suppressed.
The control unit 6 moves the first movement portion 50a so that the end 59a of the first cooling port 58a of the first cooling duct 60a in −Y direction is disposed at a position away by the predetermined distance D in +Y direction from the end of the sheet S subjected to the fixing process in +Y direction.
When the outer circumferential surface of the fixing belt 38 facing the first cooling port 58a is cooled by the first cooling wind W, the fixing belt 38 in the periphery of the first cooling port 58a is also cooled by heat transmission. In the foregoing configuration, substantially the entire sheet non-passing region A2 is cooled while suppressing the cooling of the sheet passing region A1 of the fixing belt 38. Accordingly, the sheet non-passing region A2 of the fixing belt 38 is efficiently cooled.
The control unit 6 causes the cooling device 40 to operate when the width of the sheet S subjected to the fixing process in Y direction is less than the predetermined width.
When the width of the sheet S in Y direction is large, most of the fixing belt 38 is deprived of heat by the sheet S. Therefore, the temperature of the sheet non-passing region A2 of the fixing belt 38 is rarely high. In contrast, when the width of the sheet S in Y direction is less than the predetermined width, there is a possibility that the temperature of the sheet non-passing region A2 of the fixing belt 38 becomes high. In the foregoing configuration, since the operation of the cooling device 40 is limited to a necessary case, power consumption of the cooling device 40 can be suppressed.
The control unit 6 causes the cooling device 40 to operate when the number of sheets S continuously subjected to the fixing process is equal to or greater than a predetermined number.
When the number of sheets S continuously subjected to the fixing process is small, a temperature difference is small between the sheet passing region A1 deprived of heat by the sheet S and the sheet non-passing region A2 not deprived of heat by the sheet S. That is, the temperature of the sheet non-passing region A2 of the fixing belt 38 is less likely to become high. In contrast, when the number of sheets S continuously subjected to the fixing process is equal to or greater than the predetermined number, the temperature difference is large between the sheet passing region A1 and the sheet non-passing region A2. That is, there is a possibility that the temperature of the sheet non-passing region A2 of the fixing belt 38 becomes high. In the foregoing configuration, since an operation of the cooling device 40 is limited to a necessary case, power consumption of the cooling device 40 can be suppressed.
The control unit 6 causes the cooling device 40 to operate when the temperature of the end of the fixing belt 38 in Y direction is equal to or higher than the predetermined temperature.
In this configuration, the sheet non-passing region A2 of the fixing belt 38 is efficiently cooled.
The fixing device 130 includes the pressure roller 30p, a heating roller 130h, and the cooling device 40.
The heating roller 130h includes a heating lamp (heat source) 134, a reflection member 137, a support member 136, a pressure pad 139, and a fixing belt (rotator) 138. The heating lamp 134, the reflection member 137, the support member 136, and the pressure pad 139 stretches in a direction of a rotation axis C of the fixing belt 138 and are disposed inside the fixing belt 138.
The heating lamp 134 is disposed near the rotation axis C of the fixing belt 138. For example, the heating lamp 134 is a halogen lamp.
The reflection member 137 is disposed on the side of the pressure roller 30p with respect to the heating lamp 134. The reflection member 137 stretches to surround the heating lamp 134. The reflection member 137 reflects heat radiated from the heating lamp 134 toward the inner circumferential surface of the fixing belt 138.
The support member 136 is disposed on the side of the pressure roller 30p with respect to the reflection member 137. The support member 136 supports the heating lamp 134, the reflection member 137, and the pressure pad 139.
The pressure pad 139 is disposed on the side of the pressure roller 30p with respect to the support member 136. For example, the pressure pad 139 is formed of a soft material such as silicon rubber.
The fixing belt 138 is a cylindrical endless belt.
When the pressure roller 30p comes into contact with the heating roller 130h, the nip N is formed between the pressure roller 30p and the fixing belt 138. The pressure pad 139 inside the fixing belt 138 is deformed and the width of the nip N in the transport direction of the sheet S is ensured. When the pressure roller 30p is rotatably driven, the fixing belt 138 is driven to rotate about the rotation axis C by a frictional force. When the sheet S is passed through the nip N, the toner images transferred to the sheet S are heated and pressurized. Thus, the fixing device 130 fixes the toner images to the sheet S.
The fixing belt 138 according to the modification example is cooled by the cooling device 40 similar to that of the embodiment. Thus, the sheet non-passing region of the fixing belt 138 is efficiently cooled.
The image processing apparatus according to the embodiment is the image forming apparatus 1 and a heating device is the fixing device 30. On the other hand, the image processing apparatus may be a decoloring apparatus and the heating device may be a decoloring unit. The decoloring apparatus performs a process of decoloring (erasing) an image formed on a sheet by decoloring toner. The decoloring unit heats a decoloring toner image formed on a sheet passing through a nip for the decoloring. The decoloring unit is cooled by the cooling device 40 similar to that of the embodiment. Thus, a sheet non-passing region of the rotator is efficiently cooled.
According to at least one of the above-described embodiments, the first introduction duct 54a stretching in +Y direction as approaching the rotation axis C of the fixing belt 38 is included. Thus, the sheet non-passing region A2 of the fixing belt 38 is efficiently cooled.
While certain embodiments have been described these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms: furthermore various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and there equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
