JP2004361796A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic induction type fixing device capable of appropriately cooling a switching element without making a cooling means act at all times, and an image forming apparatus equipped with the fixing device. <P>SOLUTION: The induction heat type fixing device has a heating rotational body, a magnetic field generating means and a power source unit which supplies an AC current to the magnetic field generating means, and causes the heating rotational body to generate heat by electromagnetic induction with high frequency induction magnetic flux, thereby heating and fixing a toner image formed on a recording medium. The power source unit is equipped with the switching element, a switching element temperature detection means for detecting the temperature of the switching element, and a switching element cooling means for cooling the switching element, and is constituted so that the switching element cooling means can act when the temperature of the switching element reaches specified temperature. The image forming apparatus is equipped with the fixing device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, and an image forming apparatus including the fixing device. More specifically, the present invention relates to a fixing device that heats and fixes an object to be heated such as a recording medium carrying an image by using electromagnetic induction, and an image forming apparatus provided with an induction heating type fixing device.
[0002]
[Prior art]
An electromagnetic induction-type fixing device generally has a heating unit using electromagnetic induction and a pressing unit that rotates while being pressed against the heating unit, and the toner image is carried by the heating unit and the pressing unit. The fixed recording medium is nipped and conveyed to perform fixing. The heating means has a spring-shaped coil or a vertically wound coil and a core as needed inside a roll or belt-shaped rotating heating element, and preferably supplies a high-frequency alternating current of 20 kHz or more to the coil to supply an alternating current. A means for generating a magnetic flux to induce an eddy current in the heating element and heating and fixing the toner image by heat generated by the eddy current loss.The heat fixing of the toner image on the recording medium is performed under elastic pressure contact of the pressing means. Done.
[0003]
The fixing device using the electromagnetic induction has excellent characteristics, such as being able to heat and fix at a rapid rise with the supply of a high-frequency alternating current, without waste of power consumption, as compared with a fixing device using a conventional halogen lamp. In recent years, research and development on a fixing device using electromagnetic induction have been advanced, and a technology regarding a fixing device using electromagnetic induction has been proposed (for example, see Patent Document 1).
[0004]
In order to heat the heating means of the electromagnetic induction type, a power supply unit for generating a high-frequency current is necessary to supply a high-frequency current to the coil. And a switching element cooling means such as a cooling fan.
[0005]
[Patent Document 1]
JP-A-2002-116656 (pages 3 to 6, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, if this switching element cooling means is constantly operated, there are problems such as an increase in power consumption and annoying noise.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems and to provide a fixing device using electromagnetic induction capable of appropriately cooling a switching element without constantly operating a switching element cooling unit, and an image forming apparatus including the fixing device. Is to provide.
[0008]
[Means for Solving the Problems]
The above object is achieved by the following constitutions.
[0009]
(1) a heating rotator made of a conductive member, a magnetic field generating means arranged near the heating rotator, and a power supply unit for supplying an alternating current to the magnetic field generating means; In the induction heating type fixing device, the generated high-frequency induction magnetic flux causes the heating rotator to generate heat by electromagnetic induction, and heats and fixes the toner image formed on the recording medium.
The power supply unit includes a switching element, a switching element temperature detecting unit that detects a temperature of the switching element, and a switching element cooling unit that cools the switching element.
The fixing device is characterized in that the switching element cooling means operates when the temperature of the switching element reaches a predetermined temperature.
[0010]
(2) The switching element cooling means comprises a switching element cooling fan capable of switching the air flow, and is configured such that when the temperature of the switching element reaches a predetermined temperature, the air flow of the switching element cooling fan increases. The fixing device according to (1), wherein:
[0011]
(3) a heating rotator made of a conductive member, a magnetic field generating means arranged near the heating rotator, a heating rotator temperature detecting means for detecting a temperature of the heating rotator, and a magnetic field generating means. A power supply unit for supplying an alternating current, wherein the high-frequency induction magnetic flux generated from the magnetic field generation means causes the heating rotator to generate heat by electromagnetic induction, thereby heating and fixing the toner image formed on the recording medium. In the induction heating type fixing device,
The power supply unit includes a switching element, a switching element temperature detecting unit that detects a temperature of the switching element, and a switching element cooling unit that cools the switching element.
When the temperature of the heating rotator detected by the heating rotator temperature detecting means and the temperature of the switching element detected by the switching element temperature detecting means reach a predetermined temperature, the switching element cooling means operates. A fixing device.
[0012]
(4) image forming means for forming a toner image on a recording medium, and a fixing device for heating and fixing the toner image,
An image forming apparatus comprising the induction heating type fixing device according to any one of (1) to (3).
[0013]
(5) a heating rotator made of a conductive member, a magnetic field generating means arranged near the heating rotator, a heating rotator temperature detecting means for detecting a temperature of the heating rotator, and an alternating magnetic field generator An induction heating device having a power supply unit for supplying a current and causing the heating rotator to generate heat by electromagnetic induction by high-frequency induction magnetic flux generated from the magnetic field generation means, thereby heating and fixing the toner image formed on the recording medium. Mold fixing device,
A control unit for controlling the operation of the fixing device and each unit.
The power supply unit includes a switching element, and a switching element cooling unit that cools the switching element, and
The control means controls the value of the alternating current supplied to the magnetic field generating means by issuing a command to the power supply unit based on the temperature detected by the heating rotator temperature detecting means, according to the value of the alternating current. An image forming apparatus configured to control an operation of the switching element cooling unit.
[0014]
(6) a heating rotator made of a conductive member, a magnetic field generating means arranged in the vicinity of the heating rotator, a heating rotator temperature detecting means for detecting the temperature of the heating rotator, and an alternation to the magnetic field generating means A power supply unit for supplying a current, wherein the high-frequency induction magnetic flux generated from the magnetic field generating means causes the heating rotary body to generate heat by electromagnetic induction, thereby heating and fixing the toner image formed on the recording medium. A heating type fixing device,
Control means for controlling the operation of each part;
An internal cooling fan for cooling the inside of the image forming apparatus,
The power supply unit includes: a switching element; a switching element temperature detecting unit that detects a temperature of the switching element; and a radiator plate that promotes heat radiation of the switching element.
An image forming apparatus, wherein the heat radiating plate is arranged in an air flow passage of the internal cooling fan.
[0015]
(7) a heating rotator made of a conductive member, a magnetic field generating means arranged near the heating rotator, a heating rotator temperature detecting means for detecting the temperature of the heating rotator, and an alternating magnetic field generator A power supply unit for supplying a current, wherein the high-frequency induction magnetic flux generated from the magnetic field generating means causes the heating rotary body to generate heat by electromagnetic induction, thereby heating and fixing the toner image formed on the recording medium. A heating type fixing device,
Control means for controlling the operation of each part of the image forming apparatus;
In the image forming apparatus having a cooling fan inside the device of a variable air flow to cool the inside of the image forming device,
The power supply unit, a switching element, a switching element temperature detecting means for detecting the temperature of the switching element, a heat radiating plate for promoting heat radiation of the switching element, a variable air flow switching element cooling fan for cooling the switching element, With
The radiator plate is disposed in an airflow passage by the cooling fan in the device,
When the in-apparatus cooling fan is operated, the control unit controls an air flow of the switching element cooling fan according to an air flow of the in-apparatus cooling fan based on a program created in advance. Forming equipment.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a fixing device and an image forming apparatus of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a sectional configuration diagram showing an embodiment of an image forming apparatus provided with a fixing device according to the present invention.
[0018]
The image forming apparatus shown in FIG. 1 is provided with a charging unit 2, an exposing unit 3, a developing unit 4, a transferring unit 5, a discharging unit 5A, a separating unit 6, and a cleaning unit 7 around a rotating photoreceptor 1. is there. After the surface of the photoreceptor 1 is uniformly charged by the charging means 2, a latent image is formed by irradiating the laser of the exposure means 3 with light based on image data read from the document. The toner image is formed on the surface of the photoconductor 1 by reversal development by the developing unit 4 to which a bias is applied.
[0019]
On the other hand, the sheet (recording medium) P fed from the sheet storage unit 8 is sent to a transfer position, and the toner image is transferred onto the sheet P by the transfer unit 5 at the transfer position. Thereafter, the charge on the back surface of the sheet P is erased by the charge removing means 5A, and the sheet P is separated from the photoreceptor 1 by the separating means 6. An intermediate conveyance section 9 and a fixing device 10 are provided downstream of the separation means 6, and the paper P separated by the separation means 6 is conveyed by the intermediate conveyance section 9, heated and fixed by the fixing device 10, and discharged. The paper is discharged to the paper plate 11. On the other hand, the developer remaining on the surface of the photoreceptor 1 is removed by the cleaning unit 7 downstream of the separating unit 6 to prepare for the next image formation.
[0020]
The fixing device 10 according to the present invention includes a power supply unit 101 and a fixing device main body 100. The power supply unit 101 is disposed above the substrate of the image forming apparatus, the substrate 102, the switching element 103 electrically and mechanically joined to the substrate 102, the heat sink 104 closely attached to the switching element 103, and the main body of the image forming apparatus. The cooling device includes a switching element cooling fan 13 serving as a switching element cooling means, and at least the heat radiating plate 104 is provided in a ventilation path T connecting the ventilation port 12 formed on the side surface of the main body of the image forming apparatus and the switching element cooling fan 13. Will be arranged. The switching element cooling fan 13 is a fan that can change the air volume by, for example, a Hi-Lo switching method. In the embodiment, the switching element cooling fan 13 is provided above the image forming apparatus main body (it can be shared with the apparatus cooling fan for cooling the inside of the image forming apparatus). It may be arranged near the unit 101. The fixing device main body 100 will be described later in detail.
[0021]
FIG. 2 is a partial cross-sectional view illustrating a configuration around a switching element in the power supply unit of the fixing device according to the present invention.
[0022]
In FIG. 2, reference numeral 102 denotes a substrate on which an electric circuit for controlling the operation of the fixing device 10 is mounted. Reference numeral 103 denotes an IGBT (insulated gate bipolar transistor) electrically and mechanically joined to the substrate 102 by soldering. It is a switching element like this. Reference numeral 104 denotes a radiator plate fixedly attached to the switching element 103, and is formed of an aluminum material having a high thermal conductivity. TS2 is a temperature detecting element (switching element temperature detecting means) such as a thermistor attached to the heat sink 104, and the temperature of the switching element 103 is detected by the temperature detecting element TS2. It is desirable that the temperature detection element TS2 be installed near the switching element 103.
[0023]
FIG. 3 is a front sectional view showing an embodiment of the fixing device main body according to the present invention, and FIG. 4 is a side sectional view of the fixing device main body.
[0024]
The fixing device main body 100 includes a fixing roller 110, a pressure roller 140, and the like. Around the fixing roller 110, a cleaning roller 150, an oil application roller 160, and the like are disposed.
[0025]
The fixing roller 110 includes a heating rotator 120 having electromagnetic induction heat generation, and a magnetic field generating unit 130 disposed inside the heating rotator 120. A surface layer (release layer) 121 is formed on the outer peripheral surface of the heating rotator 120. The magnetic field generating means 130 includes a magnetic core 131 and an exciting coil 132.
[0026]
The pressure roller 140 is configured by coating an elastic layer 142 such as silicone rubber around a cored bar 141, and further covering a fluororesin (coating layer) 143 as an outermost layer. N is a fixing nip portion where the pressure roller 140 and the fixing roller 110 are pressed against each other.
[0027]
When the fixing roller 110 is driven and rotated to form a magnetic field from the magnetic field generating means 130, the magnetic field acts on the heating rotator 120 in the fixing nip portion N, and the heating rotator 120 is generated from the magnetic field generating means 130. Electromagnetic induction heat is generated by the generated high frequency induction magnetic flux. In this state, a recording medium (hereinafter, referred to as a sheet) P is introduced into a fixing nip portion N where the heating rotator 120 and the pressure roller 140 are pressed against each other, and the heat of the heating rotator 120 is applied to the sheet P. The toner image on P is heated and fixed.
[0028]
The heating rotator 120 is mainly made of an iron core having magnetism and good thermal conductivity. The surface of the heating rotator 120 is coated with a perfluoroacrylate (PFA) tube or a polytetrafluoroethylene (PTFE) tube or a fluororesin (PFA or PTFE) in order to improve the releasability from the toner. ) The release layer 121 may be provided by applying a paint or by molding silicone rubber or fluorine rubber.
[0029]
The magnetic field generating means 130 includes a magnetic core 131 and an exciting coil 132 wound around the magnetic core 131. The excitation coil 132 is connected to the power supply unit 101 via the conductor 170.
[0030]
An alternating magnetic field H is formed inside the heating rotator 120 by the magnetic flux generated from the magnetic field generating means 130, and the heating rotator 120 is heated. The heating rotator 120 is rapidly heated by an alternating magnetic field H formed inside by a magnetic flux generated from the magnetic field generating means 130. That is, in the heating rotator 120, an electric current flows through the excitation coil 132, and an alternating magnetic field H of about 20 to 50 kHz is formed inside the heating rotator 120 by the magnetic flux generated from the magnetic core 131, and the alternating magnetic field H is generated by the alternating magnetic field H. The heating rotator 120 is heated by the eddy current inside the heating rotator 120.
[0031]
The magnetic core 131 is made of a material having high magnetic permeability and low residual magnetic flux density, such as ferrite and permalloy, to increase the magnetic flux generated by the exciting coil 132. Alternatively, the current flowing through the heating rotator 120 is increased by increasing the change in the magnetic flux.
[0032]
Various configurations are used for the magnetic field generating means 130. The magnetic core 131 of the magnetic field generating means 130 shown in FIG. 3 has an I-shape having one center wall, but has a U-shape having two side walls, and has one center wall and two side walls. An E-shaped configuration is also applicable.
[0033]
A pressure roller 140 as a lower cylindrical fixing member that forms a pair with the upper fixing roller 110 includes, for example, a metal core 141 using an aluminum material, and a silicone rubber layer or a silicone rubber layer on the outer peripheral surface of the metal core 141. It is configured as a soft roller having an outer diameter of about 25 to 50 mm on which an elastic layer 142 made of a fluorine rubber layer or a sponge-like thick rubber layer using a foam material of silicone rubber is formed. On the outer side (outer peripheral surface) of the elastic layer 142, a coating layer 143 formed by coating a tube (not shown) of a heat-resistant fluororesin such as PFA or PTFA having releasability is formed. An elastic rubber roller having high heat insulation is used for the lower pressure roller 140 to prevent the diffusion of heat from the upper heating rotator 120 to the lower pressure roller 140 and to secure a wide nip width. A planar fixing nip N is formed between the upper heating rotator 120 and the lower pressure roller 140, and the toner image is fixed.
[0034]
As shown in FIGS. 3 and 4, a plurality of temperature detecting elements (heating rotator temperature detecting means) TS1 for detecting the surface temperature of the heating rotator 120 are arranged near the outer peripheral surface of the heating rotator 120. The temperature detecting element TS1 is disposed near the outer peripheral surface at the axial center and both ends of the heating rotator 120. The temperature detection element TS1 detects the surface temperature of the heating rotator 120, and the amount of current applied from the excitation circuit (not shown) to the magnetic field generating means 130 is controlled by the detection signal.
[0035]
FIG. 5 is a block diagram for explaining control of the fixing device and the image forming apparatus according to the present invention.
[0036]
The control means 190 provided in the image forming apparatus main body causes the temperature of the heating rotator 120 in the fixing apparatus main body 100 to be detected by the temperature detecting element TS1. The control means 190 compares the set value of the program stored in advance in a memory (not shown) of the control means 190 with the detected value, and when the detected value exceeds the set value, the control unit 190 The energization is turned off, and when the detected value becomes equal to or less than the set value, the excitation coil 132 is energized to control the temperature of the heating rotator 120 to be appropriately maintained.
[0037]
Further, the control unit 190 receives the detection signal of the temperature of the switching element 103 from the temperature detection element TS2, issues a command to the switching element cooling fan 13, and controls the operation. The control (switching) of the operation may be switching of the operation and stop of the switching element cooling fan 13 or switching of the air flow Hi / Lo.
[0038]
Further, the temperature of the heating rotator 120 is taken into a set value of a program stored in a memory (not shown) of the control means 190, and when the temperature of the heating rotator 120 reaches a predetermined temperature, the switching element cooling of the power supply unit 101 is performed. It is also possible to operate the fan 13.
[0039]
Furthermore, a program may be created in which the temperature of the heating rotator 120 and the temperature of the switching element 103 are combined, and the operation of the switching element cooling fan 13 may be controlled based on the combination of the temperatures.
[0040]
FIG. 6 is a flowchart for explaining the procedure of the embodiment according to the switching operation of the switching element cooling fan of the present invention.
[0041]
The control means 190 causes the temperature detection element TS2 to detect the temperature of the switching element 103 (S11), and compares the detected value with a set value of a program stored in advance in a memory (not shown) of the control means 190 ( S12) If the detected value exceeds the set value, control is exercised to operate the switching element cooling fan 13 (S13). When the detected value becomes equal to or less than the set value, the control unit 190 issues a command to the switching element cooling fan 13 to stop the switching element cooling fan 13 (S14). (However, when the image forming apparatus is in the standby state and the fixing device is not in the heating state, the switching element cooling fan 13 is stopped regardless of the detected value.)
FIG. 7 is a flowchart illustrating a procedure of an embodiment relating to switching of the air flow rate of the switching element cooling fan of the present invention.
[0042]
The difference from the invention described with reference to FIG. 6 is that, in the invention of FIG. 6, the switching element cooling fan 13 is switched by operating and stopping, whereas in the invention of FIG. 7, the operation of the switching element cooling fan 13 is set to the Hi state ( The point is that the air flow is switched between a large air volume) and a Lo state (small air volume). The other steps are the same, and the description is omitted.
[0043]
FIG. 8 is a flowchart for explaining a procedure in another embodiment according to the switching operation of the switching element cooling fan of the present invention.
[0044]
The control means 190 causes the temperature detecting element TS1 to detect the temperature of the heating rotator (S31), and the program setting value (predetermined value) stored in advance in a memory (not shown) of the control means 190 and the detected value (S32). When the detected value has not reached the predetermined value, the process returns to S31, and when the detected value has reached the predetermined value, the process proceeds to S33. The control unit 190 causes the temperature detection element TS2 to detect the temperature of the switching element 103 (S33), and compares the detected value with a set value of a program stored in a memory (not shown) of the control unit 190 in advance (S33). S34) If the detected value exceeds the set value, control is performed so that the switching element cooling fan 13 operates (S35). When the detected value becomes equal to or less than the set value, the control unit 190 issues a command to the switching element cooling fan 13 to stop the switching element cooling fan 13 (S36).
[0045]
In this embodiment, it is needless to say that the switching of the operation and the stop of the switching element cooling fan 13 may be performed by switching the air volume (Hi, Lo).
[0046]
FIG. 9 is a flowchart for explaining the procedure of another invention relating to the switching of the air flow rate of the switching element cooling fan of the present invention.
[0047]
In the image forming apparatus in which the output power of the power supply unit of the fixing device can be switched between Hi / Lo, when the power is turned on when the entire image forming apparatus, particularly, the fixing device is not sufficiently preheated, the control unit 190 , The current value input to the excitation coil 132 becomes Hi (the output power becomes Hi) (S41). At this time, the control unit 190 switches the air volume of the switching element cooling fan to Hi (S42). The surface temperature of the heating rotator 120 is detected by the temperature detecting element TS1 (S43), and the detected value is compared with a set value (predetermined value) of a program stored in a memory (not shown) of the control means 190 in advance. Then, when the detected value has not reached the predetermined value (S44), the process returns to S43, and when the detected value has reached the predetermined value, the process proceeds to S45. Next, the control unit 190 sets the current value input to the exciting coil 132 to Lo (the output power becomes Lo) (S45), and further switches the air volume of the switching element cooling fan 13 to Lo (S46).
[0048]
【The invention's effect】
As described above, by the operation of the switching element cooling fan or the switching of the air volume according to the present invention, efficient fixing without unnecessary cooling is performed, and a fixing device and an image forming apparatus with low power consumption and low noise are provided. Becomes possible.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram illustrating an embodiment of an image forming apparatus including a fixing device according to the present invention.
FIG. 2 is a partial cross-sectional view illustrating a configuration around a switching element in a power supply unit of the fixing device according to the present invention.
FIG. 3 is a front sectional view showing an embodiment of the fixing device main body of the present invention.
FIG. 4 is a side sectional view of a fixing device main body of the present invention.
FIG. 5 is a block diagram for describing control of the fixing device according to the present invention.
FIG. 6 is a flowchart for explaining a procedure of an embodiment relating to operation switching of the switching element cooling fan of the present invention.
FIG. 7 is a flowchart showing a procedure of an embodiment relating to switching of the air flow rate of the switching element cooling fan of the present invention.
FIG. 8 is a flowchart for explaining a procedure of another embodiment according to the switching operation of the switching element cooling fan of the present invention.
FIG. 9 is a flowchart for explaining a procedure of another invention relating to the switching of the air flow rate of the switching element cooling fan of the present invention.
[Explanation of symbols]
Reference Signs List 10 Fixing device 12 Vent 13 Switching element cooling fan (switching element cooling means)
REFERENCE SIGNS LIST 100 fixing device main body 101 power supply unit 103 switching element 104 heat sink 110 fixing roller 120 heating rotator 130 magnetic field generating means 140 pressing roller 190 control means T ventilation paths TS1, TS2 temperature detecting elements

Claims (7)

A heating rotator made of a conductive member, a magnetic field generating means disposed near the heating rotator, and a power supply unit for supplying an alternating current to the magnetic field generating means; An induction heating type fixing device that heats and fixes a toner image formed on a recording medium by causing the heating rotator to generate electromagnetic induction by high-frequency induction magnetic flux,
The power supply unit includes a switching element, a switching element temperature detecting unit that detects a temperature of the switching element, and a switching element cooling unit that cools the switching element.
The fixing device is characterized in that the switching element cooling means operates when the temperature of the switching element reaches a predetermined temperature. The switching element cooling means includes a switching element cooling fan capable of switching an air flow, and is configured such that when the temperature of the switching element reaches a predetermined temperature, the air flow of the switching element cooling fan increases. The fixing device according to claim 1. A heating rotator made of a conductive member, a magnetic field generating means disposed near the heating rotator, a heating rotator temperature detecting means for detecting a temperature of the heating rotator, and an alternating current to the magnetic field generating means. An induction heating type having a power supply unit for supplying, and causing the heating rotary body to generate heat by electromagnetic induction by a high-frequency induction magnetic flux generated from the magnetic field generation means, thereby heating and fixing a toner image formed on a recording medium. In the fixing device of
The power supply unit includes a switching element, a switching element temperature detecting unit that detects a temperature of the switching element, and a switching element cooling unit that cools the switching element.
When the temperature of the heating rotator detected by the heating rotator temperature detecting means and the temperature of the switching element detected by the switching element temperature detecting means reach a predetermined temperature, the switching element cooling means operates. A fixing device. An image forming unit that forms a toner image on a recording medium, and a fixing device that heats and fixes the toner image,
An image forming apparatus comprising the induction heating type fixing device according to claim 1. A heating rotator made of a conductive member, a magnetic field generating means arranged near the heating rotator, a heating rotator temperature detecting means for detecting the temperature of the heating rotator, and supplying an alternating current to the magnetic field generating means And an induction heating type fixing device that heats and fixes a toner image formed on a recording medium by causing the heating rotator to generate heat by electromagnetic induction by a high-frequency induction magnetic flux generated from the magnetic field generating means. Equipment and
A control unit for controlling the operation of the fixing device and each unit.
The power supply unit includes a switching element, and a switching element cooling unit that cools the switching element, and
The control means controls the value of the alternating current supplied to the magnetic field generating means by issuing a command to the power supply unit based on the temperature detected by the heating rotator temperature detecting means, according to the value of the alternating current. An image forming apparatus configured to control an operation of the switching element cooling unit. A heating rotator made of a conductive member, a magnetic field generating means arranged near the heating rotator, a heating rotator temperature detecting means for detecting the temperature of the heating rotator, and supplying an alternating current to the magnetic field generating means An induction heating type that heats and fixes the toner image formed on the recording medium by causing the heating rotator to generate heat by electromagnetic induction using a high-frequency induction magnetic flux generated from the magnetic field generation means. A fixing device,
Control means for controlling the operation of each part;
An internal cooling fan for cooling the inside of the image forming apparatus,
The power supply unit includes: a switching element; a switching element temperature detecting unit that detects a temperature of the switching element; and a radiator plate that promotes heat radiation of the switching element.
An image forming apparatus, wherein the heat radiating plate is arranged in an air flow passage of the internal cooling fan. A heating rotator made of a conductive member, a magnetic field generating means arranged near the heating rotator, a heating rotator temperature detecting means for detecting the temperature of the heating rotator, and supplying an alternating current to the magnetic field generating means An induction heating type that heats and fixes the toner image formed on the recording medium by causing the heating rotator to generate heat by electromagnetic induction using a high-frequency induction magnetic flux generated from the magnetic field generation means. A fixing device,
Control means for controlling the operation of each part of the image forming apparatus;
In the image forming apparatus having a cooling fan inside the device of a variable air flow to cool the inside of the image forming device,
The power supply unit, a switching element, a switching element temperature detecting means for detecting the temperature of the switching element, a heat radiating plate for promoting heat radiation of the switching element, a variable air flow switching element cooling fan for cooling the switching element, With
The radiator plate is disposed in an airflow passage by the cooling fan in the device,
When the in-apparatus cooling fan is operated, the control unit controls an air flow of the switching element cooling fan according to an air flow of the in-apparatus cooling fan based on a program created in advance. Forming equipment.

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