JP5564243B2 - Fixing apparatus and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a fixing device that heats and melts unfixed toner on a sheet while passing a recording medium carrying a toner image between a nip between a fixing roller pair or a heating belt and a roller, and an image forming apparatus equipped with the fixing device It is about.

  In recent years, in this type of image forming apparatus, a belt system capable of setting a small heat capacity has attracted attention because of demands for shortening the warm-up time in the fixing device and saving energy. In recent years, the electromagnetic induction heating method (IH) that has the potential for rapid heating and high-efficiency heating has attracted attention. From the viewpoint of energy saving when fixing color images, electromagnetic induction heating is combined with the belt method. Many products have been commercialized. When combining the belt method and electromagnetic induction heating, there is a configuration in which a device for generating a magnetic field for electromagnetic induction is arranged outside the belt because of the coil layout and ease of cooling, and the advantage that the belt can be directly heated. Many have been adopted (so-called outer packaging IH).

  In the electromagnetic induction heating method, the temperature of the coil rises due to the electrical resistance of the coil itself and the heat conduction from the heating roller or heating belt, leading to a reduction in heating efficiency of the heating roller. On the other hand, when the heating roller or the like is cooled together with the coil, the heating efficiency of the heating roller or the like is also reduced. That is, when the coil is simply cooled, there is a trade-off relationship between the cooling efficiency of the coil and the heating efficiency of the heating roller or the like.

  Therefore, a technique is disclosed in which a coil bobbin that holds the coil is formed in a hollow shape, and air is supplied to the hollow portion to air-cool the coil (see, for example, Patent Document 1).

JP 2008-9169 A

  By the way, when the fixing device is integrally formed on the coil and coil bobbin side and the heating roller side, if there is a problem that requires replacement of one part in the fixing device, the entire fixing device is replaced and needs to be replaced. There is a concern that the cost will not be reduced because parts that are not included are also subject to replacement. On the other hand, if the coil and coil bobbin side and the heating roller side are configured separately, the concern is eliminated.

  However, even if the heating roller side is configured to be detachable from the coil and coil bobbin side, if this heating roller or the like is exposed, when pulling out the heating roller side from the image forming apparatus main body, when temporarily storing on the work table, Furthermore, there is a problem that the heating roller or the like may collide with another member or the like to be damaged in any case of being pushed into the apparatus main body.

That is, if the coil and coil bobbin side and the heating roller side are simply configured separately, the safety of the heating roller and the like cannot be ensured, and measures to eliminate this are necessary. There are no special considerations.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing device that can solve the above-described problems and can reliably avoid damage to a heating roller and an image forming apparatus equipped with the fixing device.

  A first invention for achieving the above object is a fixing device for fixing an image on a recording medium, which is arranged along an outer surface of a heating member and generates a magnetic field for induction heating of the heating member. A coil, a core portion that is disposed on the opposite side of the heating member across the coil and that forms a magnetic path around the coil, a coil holding portion that is disposed along the outer surface of the heating member and holds the coil, and the coil A duct is formed in cooperation with the coil holding portion to cool the cover, and includes a cover member configured to cover the outer surface of the heating member and be detachable from the coil holding portion.

  According to the first aspect of the present invention, a method of heating and melting a toner image by inductively heating a heating member that is rotated by a magnetic field generated by a coil (outer package IH) is adopted, and the coil, the coil holding portion, and the core portion are And a unit (hereinafter referred to as a toner melting unit) provided with a cover member, a heating member, and a pressure member.

In this IH coil unit, the magnetic field generated by the coil generates eddy current in the heating member and performs magnetic induction heating. On the other hand, when the magnetic resistance in the magnetic path increases and the magnetic field strength decreases, the heating value of the heating member decreases. There is a possibility that it will be lowered and will not have a sufficient fixing action.
Here, according to the present invention, since the heating member is covered with the cover member, even if the toner melting unit is configured to be detachable from the IH coil unit, damage to the heating member can be surely avoided, and toner melting can be performed. Units can be easily attached and detached, and workability is improved.

  In addition, since a duct is formed by the coil holding portion and the cover member, and only the coil can be effectively cooled, it is possible to avoid a decrease in heat generation performance as compared with the case where the exposed heating member is also cooled.

  According to a second aspect, in the configuration of the first aspect, the coil holding portion has a coil side duct surface disposed along the outer surface of the heating member, and the cover member is disposed along the coil side duct surface. A plurality of ribs projecting into the duct are formed on at least one of the coil side duct surface and the housing side duct surface.

  According to the second invention, in addition to the operation of the first invention, if the duct is formed by the coil side duct surface of the coil holding portion and the housing side duct surface of the cover member, the number of parts can be reduced. In addition, since a plurality of ribs protrude in the duct, the surface area provided for cooling the coil is increased, and the cooling efficiency of the coil is improved.

According to a third invention, in the configuration of the second invention, the plurality of ribs are formed on the coil side duct surface at substantially equal intervals, and the coil is wound around the ribs.
According to the third invention, in addition to the action of the second invention, if the coil is wound around the rib, only this coil can be directly cooled, and the cooling efficiency of the coil is further improved. Further, since the pitch between the coils is the same, a uniform magnetic field is obtained, which also contributes to the improvement of the heat generation performance.

According to a fourth aspect of the present invention, there is provided an image forming apparatus in which the first to third fixing devices are mounted and the toner image formed by the image forming unit is fixed on a sheet by using the first to third fixing devices.
According to the fourth invention, in addition to the effects of the first to third inventions, the safety of the heating member is further improved, and a good toner image is formed while ensuring the heat generation performance. The reliability of the forming apparatus is improved.

  According to the present invention, the cover member that forms a duct with the coil holding portion covers the heating member, and the fixing device capable of reliably avoiding damage to the heating member while effectively cooling only the coil, and the fixing device are mounted. An image forming apparatus can be provided.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment. FIG. 3 is a longitudinal sectional view showing a structural example of a fixing unit. It is an external appearance perspective view of the housing of FIG. It is a figure which shows the other structural example of a duct. It is a figure which shows the further another structural example of a duct.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus 1 according to an embodiment. The image forming apparatus 1 includes, for example, a printer, a copier, and a facsimile apparatus that perform printing by transferring a toner image onto the surface of a sheet as an example of a recording medium based on image information input from the outside, and a composite having these functions. It can take the form of a machine or the like. In the following embodiments, the recording medium is not limited to a sheet, and can be implemented even if the recording medium is other than a sheet (such as an OHP sheet).

An image forming apparatus 1 shown in FIG. 1 is, for example, a tandem color printer. The image forming apparatus 1 includes a square box-shaped apparatus main body 2 that forms (prints) a color image on a sheet therein, and discharges the sheet on which the color image is printed on the upper surface of the apparatus main body 2. The discharge tray 3 is provided.
In the lower part of the apparatus main body 2, a paper feed cassette 5 for storing paper is disposed. In addition, a stack tray 6 for supplying paper that is not stored in the paper feed cassette 5 to the apparatus main body 2 is disposed in the center of the apparatus main body 2. An image forming unit 7 is provided on the upper part of the apparatus main body 2, and the image forming unit 7 transmits image data such as characters and patterns transmitted from a host device such as a PC connected to the image forming apparatus 1. The image is formed on the paper based on the above.

  As shown in FIG. 1, a first transport path 9 for transporting a sheet fed from the sheet feeding cassette 5 to a secondary transfer unit 23 described later is disposed on the left side of the apparatus body 2. From the right part to the left part, a second transport path 10 for transporting the sheet fed from the stack tray 6 to the secondary transfer unit 23 is provided. A fixing unit (fixing device) 14 that performs a fixing process on a sheet on which an image has been formed by the secondary transfer unit 23 and a sheet on which the fixing process has been performed are disposed in the upper left part of the apparatus main body 2. A third conveyance path 11 that conveys the toner to the third conveyance path 11 is disposed.

  The paper feed cassette 5 can be replenished by pulling it out of the apparatus main body 2 (for example, the front side in FIG. 1). The paper feed cassette 5 includes a storage unit 16 in which at least two types of paper having different sizes in the paper feed direction can be selectively stored. Note that the paper stored in the storage unit 16 is fed out to the first conveyance path 9 side by sheet by the paper feed roller 17 and the separating roller pair 18.

The stack tray 6 can be opened and closed on the outer surface of the apparatus main body 2, and sheets are placed one by one on the manual feed portion 19 or a plurality of sheets are stacked. Note that the sheets placed on the manual feed unit 19 are fed out one by one to the second conveyance path 10 side by the pick-up roller 20 and the separating roller pair 21.
The first conveyance path 9 and the second conveyance path 10 are joined before the registration roller pair 22, and the paper that has reached the registration roller pair 22 waits here for skew adjustment and timing adjustment. Thereafter, the image is sent to the secondary transfer unit 23. The full color toner image on the intermediate transfer belt 40 is secondarily transferred to the sheet by the secondary transfer unit 23 on the sent sheet. Thereafter, the sheet on which the toner image is fixed by the fixing unit 14 is reversed in the fourth conveyance path 12 as necessary, and a full-color toner image is also formed on the surface opposite to the first by the secondary transfer unit 23. Secondary transferred. Then, after the toner image on the opposite surface is fixed by the fixing unit 14, it passes through the third conveyance path 11 and is discharged to the discharge tray 3 by the discharge roller pair 24.

The image forming unit 7 includes four image forming units 26 to 29 that form black (B), yellow (Y), cyan (C), and magenta (M) toner images. An intermediate transfer unit 30 is provided which holds the toner images of the respective colors formed in 29 in a superimposed manner.
Each of the image forming units 26 to 29 is on the downstream side in the rotation direction of the photosensitive drum 32, the charging unit 33 disposed to face the circumferential surface of the photosensitive drum 32, and the photosensitive drum 32 of the charging unit 33. A laser scanning unit 34 for irradiating a laser beam to a specific position on the peripheral surface of the photosensitive drum 32, and a downstream side in the rotational direction of the photosensitive drum 32 at the laser beam irradiation position from the laser scanning unit 34. A developing unit 35 disposed opposite to the circumferential surface of the photosensitive drum 32; and a cleaning unit disposed downstream of the developing unit 35 in the rotation direction of the photosensitive drum 32 and opposed to the circumferential surface of the photosensitive drum 32. 36.

The photosensitive drums 32 of the image forming units 26 to 29 are rotated counterclockwise in the drawing by a drive motor (not shown). Further, in the developing section 35 of each of the image forming units 26 to 29, each developing device 51 contains a two-component developer containing black toner, yellow toner, cyan toner, and magenta toner.
The intermediate transfer unit 30 straddles the rear roller 38 disposed near the image forming unit 26, the front roller 39 disposed near the image forming unit 29, and the rear roller 38 and the front roller 39. The intermediate transfer belt 40 can be press-contacted with the intermediate transfer belt 40 at a position downstream of the photosensitive drum 32 in the rotation direction of the developing unit 35 of the photosensitive drum 32 of each of the image forming units 26 to 29. Four primary transfer rollers 41 are provided.

In the intermediate transfer unit 30, the toner images of the respective colors are superimposed and transferred onto the intermediate transfer belt 40 at the positions of the primary transfer rollers 41 of the image forming units 26 to 29, and finally a full-color toner image. It becomes.
The first transport path 9 and the second transport path 10 are for transporting the paper fed from the paper feed cassette 5 and the stack tray 6 to the secondary transfer unit 23 side, and in the apparatus main body 2, a predetermined transport path is formed. A plurality of conveying roller pairs 43 disposed at positions, and a registration roller pair 22 disposed in front of the secondary transfer unit 23 for timing the image forming operation and the paper feeding operation in the image forming unit 7. It has.

  The fixing unit 14 performs processing for fixing the unfixed toner image on the paper by heating and pressurizing the paper on which the toner image has been transferred by the image forming unit 7. The fixing unit 14 includes a roller pair including, for example, a pressure roller 44 and a fixing roller (heating member) 45, and the pressure roller 44 includes, for example, a metal core and an elastic surface layer (for example, silicon rubber) and the like. The fixing roller 45 has a release layer (for example, FPA), and the fixing roller 45 has a metal core and an elastic surface layer (for example, silicon sponge). A heating belt (heating member) 48 is wound around the fixing roller 45 (FIG. 2). The detailed structure of the fixing unit 14 will be described later.

  When viewed in the sheet conveyance direction, conveyance paths 47 are provided on the upstream side and the downstream side of the fixing unit 14 (FIG. 1), and the sheet conveyed through the secondary transfer unit 23 is conveyed upstream. It is introduced into a nip between the pressure roller 44 and the fixing roller 45 through a path 47. The paper that has passed between the pressure roller 44 and the fixing roller 45 is guided to the third conveyance path 11 through the conveyance path 47 on the downstream side.

The third transport path 11 transports the paper on which the fixing process has been performed by the fixing unit 14 to the discharge tray 3. For this reason, the transport roller pair 49 is disposed at an appropriate position in the third transport path 11, and the discharge roller pair 24 is disposed at the outlet thereof.
[Details of fixing unit]
Next, details of the fixing unit 14 applied to the image forming apparatus 1 of the present embodiment will be described.

  FIG. 2 is a longitudinal sectional view showing a structural example of the fixing unit 14. In FIG. 2, the orientation is turned counterclockwise by about 90 ° from the state in which the image forming apparatus 1 is mounted. Accordingly, the sheet conveying direction from the bottom to the top as viewed in FIG. 1 is from right to left as viewed in FIG. That is, the sheet P in FIG. 2 is in a state immediately before being conveyed to the fixing unit 14. In addition, when the apparatus main body 2 is larger (multifunction machine etc.), it may be mounted in the direction shown in FIG. As another layout, the fixing unit 14 may be arranged in a posture inclined left or right from the state shown in FIG.

  The fixing unit 14 of this embodiment includes the pressure roller 44, the fixing roller 45, and the heating belt 48 as described above. The pressure roller 44 is formed, for example, by forming a Si rubber layer having a thickness of about 2 to 5 mm on a metal (for example, SUS) cored bar, and further laminating a release layer (for example, FPA) on the surface layer to have a diameter of about 50 mm. It's a roller. The fixing roller 45 is a roller having a diameter of about 45 mm by laminating a silicon rubber sponge layer having a thickness of about 5 to 10 mm on a metal core (for example, SUS).

The heating belt 48 is a ferromagnetic material (for example, Ni electroformed base material) having a base material thickness of, for example, 35 μm (1 μm = 1 × 10 ⁻⁶ m), and a thin film having a thickness of about 200 to 500 μm on the surface layer. An elastic layer (for example, silicon rubber) is formed, and a release layer (for example, PFA) is formed on the outer surface, and the heat generation temperature is adjusted to a range of 150 to 200 ° C., for example. The surface temperature of the heating belt 48 is measured by a temperature sensor that is in contact with or not in contact with the heating belt 48.

As described above, since the pressure roller 44 has a silicon sponge elastic layer as a surface layer, a flat nip is formed between the heating belt 48 and the fixing roller 45. A halogen heater (not shown) is provided inside the pressure roller 44.
[IH coil unit]
In addition, the fixing unit 14 includes an IH coil unit 50 outside the fixing roller 45 and the heating belt 48 (not shown in FIG. 1). The IH coil unit 50 includes an induction heating coil (coil) 52 and ferromagnetic materials such as ferrite (relative permeability: about 1000 to 3000) so as to form a magnetic path around the induction heating coil 52. The core portion 54 has a center core, a side core, and the like.

〔coil〕
The induction heating coil 52 generates a magnetic field for induction heating the fixing roller 45 and the heating belt 48. Therefore, the induction heating coil 52 is disposed on a virtual arc surface along the outer surfaces of the fixing roller 45 and the heating belt 48. Actually, a coil bobbin (coil holding part) 53 is arranged, and the induction heating coil 52 is arranged on the coil bobbin 53 in a winding shape.

[Coil holding part]
The coil bobbin 53 is formed in a shape along the outer surfaces of the fixing roller 45 and the heating belt 48. In the posture of FIG. 2, the top surface portion extending in the horizontal direction and the outer surface of the fixing roller 45 and the heating belt 48 are covered and extended from both ends of the top surface portion. The induction heating coils 52 are respectively held on the top surface portion and the slope portion, and the lower end of the core portion 54 is supported by the slope portion. The material of the coil bobbin 53 is preferably a heat-resistant resin (for example, PPS, PET, LCP), and the coil 52 is fixed to the coil bobbin 53 using, for example, a silicon-based adhesive.

  More specifically, the coil bobbin 53 of the present embodiment has a mounting surface 53b composed of the top surface portion and the inclined surface portion described above, and a coil side duct surface 53a having the same shape on the opposite side of the mounting surface 53b. Is provided. The coil side duct surface 53a faces a toner melting unit 70 described later (FIG. 1 shows a pressure roller 44 and a fixing roller 45 housed in the toner melting unit 70, and a housing 71 described later is shown. It has not been). In addition, an elastic member is provided on the end surface 53c of the coil side duct surface 53a and can be brought into close contact with the toner melting unit 70.

[Toner melting unit]
By the way, the fixing unit 14 of the present embodiment can separate the IH coil unit 50 and the toner melting unit 70 from the main body 2 of the toner melting unit 70 in the longitudinal direction of the pressure roller 44 and the fixing roller 45. That is, it can be slid in the direction perpendicular to the paper surface as seen in FIGS. As a result, the toner melting unit 70 is pulled out from the apparatus main body 2 and the IH coil unit 50 is left in the apparatus main body 2.

The toner melting unit 70 of this embodiment includes a box-shaped housing (cover member) 71, and the pressure roller 44, the fixing roller 45, and the heating belt 48 described above are accommodated in the housing 71.
[Cover member]
Specifically, the housing 71 of this embodiment includes an upper cover 72 and a lower cover 76 that extend along the longitudinal direction of the pressure roller 44 and the fixing roller 45 as shown in FIG. 3 in addition to FIG.

  The upper cover 72 has an opening directed downward as viewed in FIG. 2, and the upper cover 72 covers the fixing roller 45 and the heating belt 48. On the other hand, the lower cover 76 has an opening directed upward as viewed in FIG. 2 and covers the pressure roller 44. When the opening of the upper cover 72 and the opening of the lower cover 76 are brought into contact with each other and joined, a paper inlet 80 and a paper outlet 82 are formed. Further, both ends in the longitudinal direction of the upper cover 72 and the lower cover 76 are respectively closed by the front face 84 and the rear face 88 (FIG. 3). As shown in FIG. 3, a handle 86 used for sliding movement of the toner melting unit 70 is installed on the front face 84 of this embodiment.

On the other hand, the housing 71 of this embodiment forms a duct in cooperation with the coil bobbin 53.
More specifically, the upper cover 72 includes a housing-side duct surface 73. The housing-side duct surface 73 also has a top surface portion and a slope portion, and directly faces the coil-side duct surface 53a. To do.

  Further, as shown in FIG. 3, as shown in FIG. 3, substantially square-shaped shielding arms 74 that are bent toward the top surface portion are provided at both ends of the housing side duct surface 73 along the peripheral surface of the fixing roller 45. . Specifically, the shielding arm 74 extends toward the top surface portion of the housing-side duct surface 73 and the standing surface portion integrally formed with the inclined surface portion of the housing-side duct surface 73 and the standing surface portion. A contact surface portion. The inner side of the former standing surface portion engages with the end surface 53c of the coil side duct surface 53a, and the tip of the latter contact surface portion contacts the outer peripheral surface of the core portion 54. Thereby, the coil side duct surface 53a of the IH coil unit 50 and the housing side duct surface 73 of the toner melting unit 70 can be separated from each other at a predetermined interval. Then, if a fan (not shown) is supplied to the gap formed by the separation and the outside air is supplied by suction or delivery, the coil bobbin 53 is cooled from the coil side duct surface 53a, so that the coil carried on the coil bobbin 53 is Only 52 can be cooled. Further, the fixing roller 45 and the heating belt 48 are an air layer having a low thermal conductivity between the upper cover 72 having the housing-side duct surface 73 and the fixing roller 45 and the heating belt 48. 79, the fixing roller 45 and the heating belt 48 are not cooled.

Further, the gap formed by the coil side duct surface 53a and the housing side duct surface 73 is a duct shape in which the shielding arm 74 surrounds the end surface 53c and there is almost no gap, and leakage of air supplied by the fan is performed. Does not occur.
When the IH coil unit 50 and the toner melting unit 70 are separated, when the operator pulls out the housing 71 toward the front side as viewed in FIG. 2 using the handle 86, the shielding arm 74 is placed on the end surface 53c. As a result, only the toner melting unit 70 is pulled out from the apparatus main body 2 with the front face 84 as the head. On the other hand, when the housing 71 is pushed in with the rear surface 88 as the head, the shielding arm 74 is guided to the end surface 53c, and the toner melting unit 70 can be returned to the apparatus main body 2.

[Other structural examples of ducts]
By the way, the above-mentioned duct may be provided with a fin function.
Specifically, in the duct shown in FIG. 4 as well, the coil side duct surface 53a of the IH coil unit 50 and the housing side duct surface 73 of the toner melting unit 70 are spaced apart from each other at a predetermined interval, as in the above embodiment. However, in the present embodiment, a plurality of ribs 90 are provided on the coil side duct surface 53 a along the longitudinal direction of the pressure roller 44 and the fixing roller 45. These ribs 90 are provided at substantially equal intervals and protrude from the coil side duct surface 53 a toward the housing side duct surface 73. Instead of this example, the rib 90 may protrude from the housing-side duct surface 73.

[Other examples of duct structure]
On the other hand, the above-described coil 52 may be disposed in the duct. That is, the duct shown in FIG. 5 has a plurality of ribs 90 protruding from the coil side duct surface 53a, as in the example of FIG. However, in this embodiment, the coil 52 is wound around the rib 90 and the outside air in the duct is directly applied to the coil 52.

  As described above, according to the present embodiment, a method (outer package IH) is used in which the fixing roller 45 and the heating belt 48 rotated by the magnetic field generated by the induction heating coil 52 are induction-heated to heat and melt the toner image. The IH coil unit 50 including the induction heating coil 52, the coil bobbin 53, and the core portion 54, and the toner melting unit 70 including the housing 71, the fixing roller 45 and the heating belt 48, and the pressure roller 44. ing.

In the IH coil unit 50, the magnetic field generated by the induction heating coil 52 generates eddy currents in the fixing roller 45 and the heating belt 48, thereby performing magnetic induction heating.
Here, since the fixing roller 45 and the heating belt 48 are covered with the housing 71, the fixing roller 45 and the heating belt 48 can be reliably damaged even when the toner melting unit 70 is configured to be detachable from the IH coil unit 50. This can be avoided, and the toner melting unit 70 can be easily detached and the workability can be improved.

Further, since the duct is formed by the coil bobbin 53 and the housing 71, and only the induction heating coil 52 can be effectively cooled, the fixing roller 45 and the heating belt 48 can be compared with the case where the fixing roller 45 and the heating belt 48 are exposed. Since the heating belt 48 is not cooled, a decrease in heat generation performance can be avoided.
Furthermore, if gas is used for cooling the induction heating coil 52, the cost can be reduced as compared with the case of liquid cooling.

  Furthermore, if a duct is formed by the coil side duct surface 53a of the coil bobbin 53 and the housing side duct surface 73 of the housing 71, the number of parts can be reduced, and as shown in FIGS. Since the plurality of ribs 90 project inside, the surface area provided for cooling the induction heating coil 52 is increased, and the cooling efficiency of the induction heating coil 52 is improved.

Further, as shown in FIG. 5, if the induction heating coil 52 is wound around the rib 90, only the induction heating coil 52 can be directly cooled, and the cooling efficiency of the induction heating coil 52 is further improved. Furthermore, since the pitch between the induction heating coils 52 is the same, a uniform magnetic field is obtained, which also contributes to the improvement of the heat generation performance.
Further, the safety of the fixing roller 45 and the heating belt 48 is enhanced, and the heat generation performance is ensured and a good toner image is formed. As a result, the reliability of the image forming apparatus 1 is improved.

The present invention can be implemented with various modifications without being limited to the above-described embodiments. For example, the configuration of the core portion 54 may be either a rotating center core or a fixed center core, and can be appropriately modified.
In the present embodiment, an example in which the image forming apparatus is embodied in a printer is shown. However, the image forming apparatus of the present invention is naturally applicable to a multifunction machine, a copier, a facsimile machine, and the like.

  In any of these cases, similarly to the above, there is an effect that damage to the heating roller or the like can be surely avoided.

1 Printer (image forming device)
7 Image forming unit 14 Fixing unit (fixing device)
45 Fixing roller (heating member)
48 Heating belt (heating member)
50 IH coil unit 52 Induction heating coil (coil)
53 Coil bobbin (coil holder)
53a Coil side duct surface 54 Core portion 70 Toner melting unit 71 Housing (cover member)
73 Housing side duct surface 90 Rib

Claims (4)

A fixing device for fixing an image on a recording medium,
A heating member;
A pressure member facing the heating member;
A coil that is disposed along an outer surface of the heating member and generates a magnetic field for induction heating the heating member;
A core part disposed on the opposite side of the heating member across the coil, and forming a magnetic path around the coil;
A coil holding part that is disposed along the outer surface of the heating member and holds the coil;
A cover member that covers the outer surface of the heating member and the pressure member, and stores the heating member and the pressure member inside;
A duct formed between the coil holding part and the cover member for circulating air for cooling the coil ;
It is integrally formed on the outer surface of the cover member, and surrounds the end of the coil holding portion viewed from the side perpendicular to the air flow direction by the duct, and comes into contact with the outer peripheral surface of the core portion. And a shielding arm for closing the duct at
The fixing is characterized in that the cover member is detachably supported with respect to the coil holding portion, and the heating member and the pressure member together with the cover member are detachable with respect to the coil holding portion. apparatus. The fixing device according to claim 1,
The coil holding portion has a coil side duct surface disposed along the outer surface of the heating member, and the cover member has a housing side duct surface disposed along the coil side duct surface. ,
A fixing device, wherein a plurality of ribs projecting into the duct are formed on at least one of the coil side duct surface and the housing side duct surface. The fixing device according to claim 2,
The fixing device is characterized in that the plurality of ribs are formed at substantially equal intervals on the coil side duct surface, and the coils are wound around the ribs.   An image forming apparatus comprising: the fixing device according to claim 1 mounted on an image forming apparatus; and using this, the toner image formed by the image forming unit is fixed on a sheet.

Images