JP3447677B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., and in particular, a heat roller in which a coil is inserted and induction heating is performed using the coil, and the heat roller. Cooling air ventilation means for forcibly passing cooling air for cooling the coil therein, and the coil is inserted and is inserted into the heat roller while separating the cooling air from the heat roller. The present invention relates to a fixing device including a cooling air guide member for guiding along a coil.

[0002]

2. Description of the Related Art One of fixing devices mounted in image forming apparatuses such as copying machines, printers, and facsimiles is a fixing device that employs an induction heating type heat roller.
The induction heating type heat roller is induction-heated by using a coil inserted therein. The eddy current is induced in the heat roller by the magnetic flux generated by passing the high frequency current through the coil, and the heat roller is heated by the Joule heat accompanying this eddy current. Since the heat roller itself generates heat when using the induction heating method, the response and efficiency are better than when using the halogen method, and expectations for shortening the warm-up time and energy saving are increasing. By the way, the temperature of the coil inside the heat roller becomes considerably high due to radiant heat from the heat roller and self-heating. Exceeding the heat resistance temperature of the winding insulation film or coating may damage the power supply, so it is necessary to take measures such as cooling the coil with a cooling fan. However, if the cooling air for cooling the coil hits the inner surface of the heat roller, it adversely affects the temperature of the heat roller to be uniformly heated and its distribution.
For example, in the technique described in Japanese Patent Laid-Open No. 2000-56598, it is proposed to provide a guide member that guides cooling air for cooling the coil along the coil while separating it from the heat roller. As shown in FIG. 2, a cylindrical guide member 10 is provided between the heat roller 101 and the coil 102.
3 is inserted, and the cooling air blown from the cooling fan 104 is guided along the coil 102 while being separated from the heat roller 101 by the guide member 103.

[0003]

However, when the guide member is provided between the heat roller and the coil as in the technique described in the above publication, the distance between the heat roller and the coil is increased. I will end up. The guide member is formed of a heat-resistant resin or the like, but there is a limit to reducing the thickness in terms of strength, and if the guide member comes into contact with the rotating heat roller, malfunction or failure of the heat roller will be caused. Therefore, there is a limit to reducing the distance between the heat roller and the guide member. The wider the distance between the heat roller and the coil, the lower the heating efficiency and the need to make the coil relatively smaller than the heat roller. The present invention has been made in view of such a conventional technique, and a cooling wind for cooling the coil is provided by attaching a heat resistant film around the coil so as to cover at least the winding of the coil. It is an object of the present invention to provide an image forming apparatus capable of bringing the heat roller and the coil close to each other while suppressing the adverse effect of the cooling air on the heat roller even when the heat roller is forcedly ventilated into the heat roller. It is what

[0004]

In order to achieve the above object, the present invention provides a heat roller in which a coil is inserted and induction heating is performed using the coil, and the coil is cooled in the heat roller. Cooling air ventilation means for forcibly passing cooling air for cooling, and for guiding the cooling air along the coil while being inserted into the heat roller and being inserted into the heat roller. In the image forming apparatus provided with the fixing device having the cooling air guide member, the cooling air guide member is a heat resistant film attached around the coil so as to cover at least the winding of the coil. It is configured as a characteristic image forming apparatus. In the present invention, a heat resistant film is attached around the coil so as to cover at least the winding of the coil in the heat roller. A heat-resistant film can be sufficiently secured as long as the strength is such that it is not broken by the wind pressure of the cooling air, and the cooling air for cooling the coil can be separated from the heat roller. Further, since it is a heat-resistant film, it cannot hold the shape for guiding the cooling air along the coil by itself, but if the cooling air pressure is present, the ventilation path for the cooling air will be opened. It can be sufficiently secured and the temperature rise of the coil can be suppressed. Moreover, the thickness of the heat resistant film is remarkably smaller than that of the guide member of the conventional device, and since the heat resistant film is attached around the coil, the distance between the heat roller and the coil can be made smaller than that of the conventional device. It is possible. Further, in the image forming apparatus, if a sticking prevention member for preventing the heat resistant film from sticking to the coil is disposed between the heat resistant film and the coil, the heat resistant film may be provided in the coil. It is possible to prevent the temperature of the coil from rising due to the fact that the cooling air is blocked by that portion of the coil.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiments are specific examples of the present invention and are not of the nature to limit the technical scope of the present invention. The image forming apparatus according to the present invention is embodied as, for example, a copying machine, a printer, or a facsimile. The fixing device according to the present invention is mounted on these image forming apparatuses. The fixing device includes, in addition to the heat roller according to the present invention, for example, a pressure roller that is brought into pressure contact with the heat roller. In this embodiment, description will be centered on the configuration related to the heat roller that is the main part of the present invention. However, the description of the other configurations of the fixing device or the image forming apparatus will be omitted. Figure 1
As shown in FIG. 2, the fixing device according to the embodiment of the present invention mounted on the image forming apparatus according to the embodiment of the present invention includes a cylindrical heat roller 1 made of a metal material, and the heat roller 1 described above. A coil 2 inserted into the heat roller 1 and wound along the rotation axis direction of the heat roller 1, and a cooling fan 3 for forcibly passing cooling air for cooling the coil 2 into the heat roller 1. , A heat-resistant film (cooling air guide member) 4 attached around the coil 2 so as to cover at least the winding wire 21 of the coil 2, and disposed between the heat-resistant film 4 and the coil 2. The heat resistant film 4
A sticking prevention member 5 for preventing the sticking of the coil 2 to the coil 2. For the heat roller 1, a metal material such as iron or nickel is used. Among the metal materials, those having high magnetic permeability are preferable. The heat roller 1 has a cylindrical shape, is rotatably supported, and is driven by using a drive gear (not shown) formed on the surface of a cylindrical member connected to the heat roller 1. The coil 2 is, for example, a bobbin 22 with a ferrite core having a central axis in a direction orthogonal to the rotation axis direction of the heat roller 1, and a winding 21 coated with an insulating film, which is spirally wound. . The cooling fan 3 is for blowing cooling air for cooling the winding wire 21 of the coil 2, and is arranged at one end of the heat roller 1. The cooling air is guided by the duct 31 and passes through the heat roller 1. The cooling air first strikes the side surface of the coil 2 at one end of the heat roller 1 and then the coil 2
And is discharged from the other end of the heat roller 1 to the outside of the heat roller 1. When the cooling air directly hits the inner surface of the heat roller 1, the heat roller 1 to be heated is also cooled. In particular, the heat roller 1 provided with the cooling fan 3
At one end of the heat roller 1, stronger wind is applied than at the other end, so that the temperature distribution becomes uneven in the rotation axis direction of the heat roller 1, and the fixing performance deteriorates. The heat resistant film 4 guides the cooling air along the coil 2 while being separated from the heat roller 1. The heat resistant film is, for example, PFA (abbreviation of tetrafluoroethylene).
Is used. The temperature in the heat roller 1 is 210 ° C.
Although it may rise to some extent, the heat resistant temperature of PFA is higher than that and is about 260 ° C. Further, the heat-resistant film 4 can be sufficiently secured as long as the strength is such that it is not broken by the wind pressure of the cooling air. The heat resistant film 4 covers the coil 2 with the tubular heat resistant film 4 as shown in FIG. 1A, or is attached to the bobbin 21 as shown in FIG. 1B. For example, the coil 2 is attached so as to cover the coil 2. In the case of the example of FIG. 1A, the position of the heat resistant film 4 may be fixed by fixing it to the duct 31 or the like. Thus, the heat resistant film 4
, The heat-resistant film 4 is made of a flexible material, so that it cannot hold the shape for guiding the cooling air along the coil 2 by itself. If there is such a wind pressure, it is possible to sufficiently secure the ventilation passage for the cooling air and suppress the temperature rise of the coil 2. Moreover, the heat-resistant film 4 has a thickness remarkably smaller than that of the guide member of the conventional device using resin or the like, and is attached around the coil 2, so that the heat-resistant film 4 between the heat roller 1 and the coil 2 is provided. The distance can be made smaller than that of the conventional device. However, the heat resistant film 4 may remain attached to the winding wire 21 of the coil 2 or the like. In this case, the ventilation passage for the cooling air is partially closed, and the coil 2
The temperature of the winding 21 may rise. Therefore, a sticking prevention member 5 for preventing the heat resistant film 4 from sticking to the coil 2 is provided, for example, in the coil 2
It is attached to the bobbin 22 of. Sticking prevention member 5
Is made of a heat-resistant material such as phenol resin.
In the example of FIG. 1A, four annular sticking prevention members 5 are attached to the bobbin 22, and the tubular heat resistant film 4 is covered on the sticking prevention members 5. Further, in the example of FIG. 1B, the U-shaped sticking prevention member 5 is attached to the upper side of the bobbin 22 outside the heat resistant film 4. By attaching the sticking prevention member 5 between the heat resistant film 4 such as the bobbin 22 and the coil 2, the heat resistant film 4 sticks to the coil 2 and a ventilation passage for the cooling air is provided. It can be prevented from blocking. The number of the sticking preventing members 5 is not limited to four, and they may be attached at an appropriate pitch in the rotation axis direction of the heat roller 1. Further, in the above embodiment, the winding wire 21 of the coil 2 is wound along the rotation axis direction of the heat roller 1, but the winding wire 21 of the coil 2 is wound along the rotation direction of the heat roller 1. The present invention can also be applied to an image forming apparatus that is wound up. For example, the present invention is applied to a coil or a cylindrical bobbin having a diameter smaller than that of the heat roller 1 and a coil formed by spirally winding the coil in the heat roller 1. Also in this case, as in the example of FIG. 1A, the heat resistant film 4 may be covered around the coil 2 and fixed to the duct 31, for example. Further, although the fan is provided only at one end of the heat roller 1 in the above-described embodiment, an exhaust fan may be provided at the other end of the heat roller 1.

[0006]

As described above, in the present invention, since the heat resistant film is attached around the coil so as to cover at least the coil in the heat roller, the coil is cooled while the cooling air is separated from the heat roller. However, the distance between the heat roller and the coil can be made significantly smaller than that of the conventional device. Further, in the image forming apparatus, if a sticking prevention member for preventing the heat resistant film from sticking to the coil is disposed between the heat resistant film and the coil, the heat resistant film may be provided in the coil. It is possible to prevent the temperature of the coil from rising due to the fact that the cooling air is blocked by that portion of the coil.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration related to a heat roller that is a main part of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a heat roller of a conventional image forming apparatus.

[Explanation of symbols]

1 ... Heat roller 2 ... coil 3 ... Cooling fan 4 ... Heat resistant film 5 ... Sticking prevention member 21 ... Winding 22 ... Bobbin

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruya Osaka Osaka 1-2-2 Tamatsukuri, Chuo-ku, Osaka Kyocera Mita Co., Ltd. (56) References JP 2000-56598 (JP, A) JP 2000 -29336 (JP, A) JP 2000-131996 (JP, A) JP 11-251053 (JP, A) JP 2000-252054 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) G03G 13/20 G03G 15/20 H05B 6/42

Claims (2)

(57) [Claims] 1. A heat roller in which a coil is inserted and which is induction-heated by using the coil, and cooling air ventilation means for forcibly passing cooling air for cooling the coil in the heat roller. An image forming apparatus including a fixing device having the coil inserted therein and the cooling air guide member inserted in the heat roller to guide the cooling air along the coil while separating the cooling air from the heat roller. The image forming apparatus, wherein the cooling air guide member is a heat resistant film attached around the coil so as to cover at least the winding of the coil. 2. The image forming apparatus according to claim 1, further comprising a sticking prevention member disposed between the heat resistant film and the coil to prevent the heat resistant film from sticking to the coil.