JP2002040843A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which approximately fixes the temperature distribution of a heat roll by resolving the problem that a paper non-feed part falls into a high temperature state because of the paper size of paper fed to the heat roll. SOLUTION: An image forming device provided with the fixing device in an induction heating system which is provided with a cylindrical heat roll 1 made of a metallic conductor and a coil 11 which is arranged on the inside of the heat roll and is wound around an axis orthogonal to the axis of rotation of the heat roll, is provided an interlinking magnetic flux shielding means 21 which locally changes the distribution of interlinking magnetic fluxes of the heat roll generated from the coil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating method in which a coil wound around an axis perpendicular to a rotation axis of the heat roller is provided inside a cylindrical heat roller made of a metal conductor. The present invention relates to an image forming apparatus having a fixing device of a system.

[0002]

2. Description of the Related Art As a fixing device provided in an image forming apparatus such as a copying machine, a facsimile, a printer, etc., a heat roller for thermally dissolving toner on a transfer sheet, and a transfer sheet which is pressed against the heat roller to form Most commonly, it is constituted by a pressure roller that presses against a heat roller. In this specification, the image forming apparatus is used in the above sense. Here, as the heat roller, a roller in which a heating element such as a halogen lamp is arranged inside the roller and the surface of the roller is heated by radiant heat from the heating element has been generally used. Hereinafter, it is referred to as a halogen system). However, such a heat roller requires a relatively long time for the roller surface to reach an appropriate temperature, and has several problems such as a large energy loss. A heat roller of an induction heating system (hereinafter, referred to as an IH system) has been proposed.

In this IH type heat roller, a coil wound around an axis in a direction orthogonal to the rotation axis of the heat roller (hereinafter referred to as a thrust winding) is provided inside a heat roller made of a metal conductor. A high-frequency current flows through the coil, an induced eddy current is generated in the heat roller by a high-frequency magnetic field generated by the high-frequency current, and the heat roller itself is joule-driven by the skin resistance of the heat roller itself. It generates heat. With such a configuration, it is possible to raise the temperature of the heat roller in a shorter time than indirect heating with a halogen lamp, etc., and it is possible to reduce energy loss due to heat generation and light leakage in parts other than the heat roller. It is.

[0004]

Incidentally, in an image forming apparatus provided with a fixing device using a heat roller regardless of the IH system or the halogen lamp system as described above,
Uniform temperature distribution in the direction of the axis of rotation of the heat roller, such as a decrease in temperature at both ends of the heat roller due to heat radiation from the openings at both ends of the heat roller, and a rise in temperature in the non-paper passing area where paper is not passed through the heat roller. Not occur. As described above, when the temperature distribution in the direction of the rotation axis of the heat roller is not uniform, the temperature at which the toner is fixed on the paper varies, so that the toner fixing state is not uniform on the paper surface, and the image quality of the copying machine is poor. Is a factor that lowers
Also, depending on the usage of the copier, the size of the paper passing through the heat roller is constant, and the non-paper passing part of the heat roller may be constantly used at a high temperature. Parts deteriorate faster. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus provided with a fixing device that makes the temperature distribution of a heat roller substantially uniform in order to solve the above-described problem.

[0005]

In order to achieve the above object, the present invention provides a cylindrical heat roller made of a metal conductor, and an inside of the heat roller having an axis perpendicular to a rotation axis of the heat roller. An image forming apparatus provided with an induction heating type fixing device having a coil wound around a coil, wherein a distribution of a linkage magnetic flux of the heat roller generated from the coil is locally changed. The image forming apparatus is provided with an interlinkage magnetic flux shielding unit. With such a configuration, by locally changing the magnetic flux linking the heat roller, the distribution of the eddy current of the heat roller can be changed, and the temperature distribution of the heat roller can be made substantially uniform.

In one embodiment of the shielding means, the shielding means is provided between the heat roller and the coil provided therein, and is fixed to a ferrite core of the coil at an intermediate portion of the heat roller. It is conceivable that the shield plate is provided so as to be orthogonal to the axis of the coil in a direction orthogonal to the rotation axis of the heat roller. With this configuration, the flux linkage at the intermediate portion of the heat roller is smaller than that at portions other than the intermediate portion. Particularly, in the case of a heat roller in which the intermediate portion of the heat roller excessively generates heat, the heat flux of the heat roller is reduced. This is effective in lowering the temperature of the intermediate portion to make the temperature distribution of the heat roller uniform.

According to another aspect of the present invention, the shielding means is provided between the heat roller and the coil provided therein, the rotation axis of which is provided in parallel with the rotation axis of the heat roller. The first shaft member and the first shaft member
A plurality of plate-shaped shielding plates divided and fixed at a front end, a middle portion, and a rear end of the shaft member, and these shielding plates are provided on the rotation axis of the first shaft member. A shielding plate provided at an intermediate portion of the first shaft member in parallel with the first shaft member;
It is conceivable that a shaft plate provided at the front end and the rear end of the first shaft member is attached at an angle difference of 90 degrees around the rotation axis of the first shaft member. With such a configuration, by rotating the first shaft member to a designated angle or an arbitrary angle, a front end portion, an intermediate portion,
In addition, the degree of shielding of the rear end portion can be arbitrarily adjusted to contribute to the uniformity of the temperature distribution of the heat roller.

In still another aspect of the present invention, the shielding means is provided between the heat roller and the coil provided therein, and is slidable in the direction of the rotation axis of the heat roller. A second shaft member provided in the direction of the rotation axis; and a plurality of plate-shaped shield plates fixed to the front end and the rear end of the second shaft member. A configuration is conceivable in which the coil is attached to the second shaft member so as to be orthogonal to the axis of the coil in a direction orthogonal to the rotation axis of the heat roller. In the case of such a configuration, by moving the second shaft member in the direction of the rotation axis of the heat roller, the heat roller corresponding to the front end, the middle portion, and the rear end of the second shaft member is moved. The linkage magnetic flux of each part can be adjusted, and the temperature distribution of the heat roller can be made substantially uniform. Further, since the distance between the coil end surface and the heat roller can be structurally reduced as compared with the case where the shielding plate is attached to the first shaft member described above, the heat roller can be maintained while maintaining high heating efficiency. The linkage magnetic flux of each part can be adjusted.

As still another aspect of the present invention, it is conceivable that the shielding means is constituted by shielding rings provided at both ends of the heat roller. This configuration prevents the magnetic flux from leaking from both ends of the heat roller, preventing the temperature from dropping at both ends of the heat roller due to the magnetic flux, and eliminating the factors that disrupt the uniformity of the heat roller temperature distribution. Further, it is possible to prevent a decrease in the heating efficiency due to the magnetic flux leakage and a decrease in the temperature at both ends of the heat roller due to heat radiation from the openings at both ends of the heat roller.

In the present invention, it is conceivable that the image forming apparatus according to claim 2 or 3 is further provided with a shielding ring according to claim 4. With this configuration, the temperature of the heat roller is controlled by adjusting the linkage magnetic flux of each part of the heat roller corresponding to the front end, the middle part, and the rear end of the first shaft member or the second shaft member. Make the distribution almost uniform,
Further, the shield ring prevents the temperature of both ends of the heat roller from lowering, and makes it possible to remove a factor that breaks the uniformity of the temperature distribution of the heat roller. In addition, it is possible to prevent a decrease in heating efficiency due to the above-described magnetic flux leakage and a decrease in temperature at both ends of the heat roller due to heat radiation from openings at both ends of the heat roller.

[0011]

Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. It should be noted that the following embodiments and examples of the present invention are merely examples embodying the present invention, and do not limit the technical scope of the present invention.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention, and FIG. FIG. 4 is a schematic configuration diagram of an image forming apparatus according to an example, FIG. 4 is an image forming apparatus according to an embodiment of the present invention, and FIG. 5 is an image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 1, an IH type fixing device Z1 according to an embodiment of the present invention is provided inside a cylindrical heat roller 1 made of a metal conductor and orthogonal to a rotation axis 100 of the heat roller 1. Coil 11 wound around the axis of direction
Is arranged. A ferrite core 12 is provided inside the coil. Here, as an example of the shielding means, the ferrite core 12 and the heat roller 1
A shielding plate 21 fixed to be in contact with the ferrite core 12 in a space between them is proposed. The shielding plate 21 is provided at an intermediate portion of the heat roller 1 in the longitudinal direction. As described above, since the magnetic flux generated by the coil 11 is shielded at the intermediate portion of the heat roller 1, the magnetic flux at the intermediate portion of the heat roller 1 is smaller than that at portions other than the intermediate portion.
The eddy current generated on the surface of the intermediate portion of the heat roller 1 is also reduced as compared with portions other than the intermediate portion, and the amount of generated heat is also reduced. However, in the configuration shown here, the shielding plate 2
Since 1 is fixed, it may not be enough to keep the temperature distribution of the heat roller 1 uniform depending on the use condition of the copying machine. In other words, it is conceivable that the temperature distribution of the heat roller changes every moment due to the usage of the copying machine, other factors, and the like. Therefore, in order to cope with such a situation, the embodiment of the present invention when the shielding means is movable and the embodiment of the present invention when the shielding means for preventing magnetic flux leakage at both ends of the heat roller are provided at both ends. An example is shown below.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, a heat roller 1 in a fixing device Z2 of the IH type according to this embodiment has a rotation axis 101 of a heat roller 1 inside a cylindrical heat roller 1 made of a metal conductor. A coil 11b wound around an axis in a direction perpendicular to the above is provided, and a ferrite core 12b is provided inside the coil, which is the same as the above-described embodiment. However, FIG. 2 is greatly different from the above embodiment in that a rotatable shielding member 30a is provided between the heat roller 1 and the coil 11b inside the heat roller 1. The shielding member 30a is a rotating shaft 3 which is an example of a first shaft member divided into a front end portion 33, an intermediate portion 34, and a rear end portion 35 from the left in the drawing.
0 is provided. The rotating shaft 30 has a front end 33
And the first shielding plate 3 of the same direction fixed to the rear end portion 35
1 and 31 and a second shielding plate 32 fixed to the intermediate portion 34. Here, as shown in the BB ′ section of FIG. 2, both the first shielding plate 31 and the second shielding plate 32 are parallel to the rotation axis 30 and around the axis of the rotation axis 30. It is mounted with a 90 degree angle difference. Another special point is that the rotation shaft 30 is configured to be rotationally controlled by a motor M via gears 30a and 30b.

Here, the situation shown in FIG. 2 is that the interlinkage magnetic flux of the heat roller 1 is
2, the front end 33 and the rear end 35 are not shielded by the first shield plate 31. Accordingly, the degree of heating at the intermediate portion 34 of the heat roller 1 is weaker than the degrees of heating at the front end 33 and the rear end 35, so that the temperature distribution of the heat roller 1 is higher at the intermediate portion 34 and higher at the front end. FIG. 2 shows a situation that is effective in making the temperature distribution of the heat roller 1 uniform when the temperature is low between the rear end 33 and the rear end 35.

Further, by rotating the rotation shaft 30 by 90 degrees around the rotation axis, it is possible to create a situation opposite to the case of FIG. 2 described above. That is, from the situation shown in FIG. 2, by rotating the rotation shaft 30 by 90 degrees around the rotation axis, the interlinkage magnetic flux of the heat roller 1 is not shielded by the second shielding plate 32 in the intermediate portion 34 but is changed to the front end portion. 33 and the rear end 35 are shielded by the first shielding plate 31. Therefore, the intermediate portion 34 of the heat roller 1
Is higher than the heating degree of the front end 33 and the rear end 35, the temperature of the temperature distribution of the heat roller 1 is low in the middle 34 and high in the front 33 and the rear 35. In this case, it can be said that it is effective to make the temperature distribution of the heat roller 1 uniform. Of course, by rotating the rotating shaft 30 at an arbitrary angle, it is possible to obtain intermediate conditions in the above-described state, and the rotating shaft 30 is driven to rotate by the motor M so as to rotate around the heat roller 1. It is also possible to automatically adjust the temperature distribution of the heat roller 1 by controlling the rotation of the motor M based on the signal of the temperature sensor provided in the heat roller 1.

As described above, by attaching the shielding plate, which is an example of the shielding means, to the rotatable rotary shaft, the linkage magnetic flux of each part of the heat roller can be adjusted, and the temperature distribution of the heat roller can be made substantially uniform. It becomes possible. Also,
The structure in which the shielding plate is mounted on the slidable sliding shaft and the shielding plate is operated instead of mounting the shielding plate on the rotatable rotating shaft as described above will be described below.

The configuration of the heat roller 1 in the IH type fixing device Z3, which is still another embodiment of the present invention, is shown in FIG.
As shown in FIG. 1, a cylindrical heat roller 1 made of a metal conductor
, A coil 11c wound around an axis perpendicular to the rotation axis 102 of the heat roller 1 is provided.
The point that c is provided is the same as in the above-described embodiments and examples. However, FIG. 3 is special in that it has the following sliding shaft 40 and shielding plates 41 and 42 provided thereon. That is, inside the heat roller 1,
Between the heat roller 1 and the coil 11c, a sliding shaft 40 which is an example of a second shaft member divided into a front end portion 43, an intermediate portion 44, and a rear end portion 45 is provided from the left as viewed in the drawing.
A third shielding plate 41 is fixed to the front end 43, and a fourth shielding plate 42 is fixed to the rear end 45 of the sliding shaft 40, respectively. Here, as shown in the cross section taken along the line CC ′ of FIG. 3, both the third shielding plate 41 and the fourth shielding plate 42 are parallel to the sliding shaft 40 and the rotating shaft of the heat roller. Attached to the second shaft member so as to be orthogonal to the axis of the coil in a direction orthogonal to the core 102. Further, a rack 51 is provided on the sliding shaft 40, and a pinion 52 meshing with the rack 51 is provided on the motor 50. Therefore, the sliding shaft 40 is slid by the motor 50, and the third shielding plate 41 and the fourth shielding plate 42 change their positions in the heat roller 1. Can be locally changed.

Here, the situation shown in FIG. 3 is that the interlinkage magnetic flux of the heat roller 1 is shielded by the shielding plates 41 and 42 at the front end 43 and the rear end 45, and the intermediate portion 44 is shielded. The situation is not shielded by the board. Therefore, the degree of heating at the intermediate portion 44 of the heat roller 1 is higher than the degree of heating at the front end 43 and the rear end 45, so that the temperature of the heat roller 1 is lower at the intermediate portion 44, and the temperature at the front end 43 and the rear is lower. FIG. 3 shows an effective situation for making the temperature distribution of the heat roller 1 uniform when the temperature is high at the end 45.

Further, by sliding the sliding shaft 40 in the direction of the rotation axis 102 of the heat roller, it is possible to create a situation opposite to the case of FIG. 3 described above. That is, from the situation shown in FIG. 3, by sliding the sliding shaft 40 toward the motor 50, the third shielding plate 41 is
To come to the position. By doing so, the flux linkage of the heat roller 1 is reduced by the shielding plate 41 to the intermediate portion 4.
4 and the front end 43 and the rear end 45 are not shielded by the shield plate. That is, the degree of heating at the intermediate portion 44 of the heat roller 1 is weaker than the degree of heating at the front end portion 33 and the rear end portion 35. Therefore, the temperature of the temperature distribution of the heat roller 1 is higher at the intermediate portion 44 and higher at the front end portion. When the temperature is low between the rear end 43 and the rear end portion 45, it is possible to provide an effective state for making the temperature distribution of the heat roller 1 uniform. In this way, by attaching the shielding plate, which is an example of the shielding means, to the slidable sliding shaft, the linkage flux of each part of the heat roller can be obtained in the same manner as when the shielding plate is attached to the rotatable rotating shaft. Can be adjusted, and the temperature distribution of the heat roller can be made substantially uniform.

As shown in FIG. 4, by providing shielding rings 60 at both ends of the heat roller 1 as an example of a shielding means, a temperature drop at both ends of the heat roller is prevented, and the temperature distribution of the heat roller is uniform. It is possible to remove the factor that breaks down. In this case, it is possible to further prevent a decrease in the heating efficiency due to the magnetic flux leakage and a decrease in the temperature at both ends of the heat roller due to heat radiation from the openings at both ends of the heat roller.

Further, by combining the shielding ring with the configuration shown in the embodiment of the present invention or another embodiment, the first shaft member or the second shaft member can be combined.
The flux distribution of each part of the heat roller corresponding to the front end, the middle part, and the rear end of the shaft member is adjusted to make the temperature distribution of the heat roller substantially uniform.
By preventing the temperature at both ends of the heat roller from dropping, it is possible to eliminate a factor that breaks the uniformity of the temperature distribution of the heat roller. Moreover, the heating efficiency is reduced due to the magnetic flux leakage,
It is possible to prevent a decrease in temperature at both ends of the heat roller due to heat radiation from openings at both ends of the heat roller.

In the above embodiment, the shielding plate 21 is provided for shielding the intermediate portion of the heat roller 1. However, in FIG. 1 shown in the embodiment of the present invention, the fixing device Z1 is marked with *. As shown in FIG.
By disposing a shielding plate 21a deformed so as to increase the area in the middle portion of the heat roller 1 in the longitudinal direction of the heat roller 1, a desired magnetic flux distribution is obtained, and the temperature distribution of the heat roller 1 is reduced. It may be uniform.

[0024]

As described above, according to the present invention, a cylindrical heat roller made of a metal conductor is wound around an axis in a direction perpendicular to the rotation axis of the heat roller inside the heat roller. An image forming apparatus provided with an induction heating type fixing device having a coil and a coil for shielding the interlinkage magnetic flux which locally changes the distribution of the interlinkage magnetic flux of the heat roller generated from the coil. Means, the distribution of the eddy current of the heat roller is changed by locally changing the magnetic flux linking the heat roller, and the temperature distribution of the heat roller is changed. Can be made substantially uniform. Further, in the configuration shown in the embodiment of the present invention, the shielding plate is immovable and fixed. Therefore, by making the shielding plate movable as shown in the embodiment,
It is also possible to keep the temperature distribution of the heat roller uniform according to the usage of the copying machine. Further, by using the shielding ring, it is possible to prevent a temperature drop at both ends of the heat roller, and to remove a factor that breaks the uniformity of the temperature distribution of the heat roller. In addition, it is possible to prevent a decrease in heating efficiency due to the above-described magnetic flux leakage and a decrease in temperature at both ends of the heat roller due to heat radiation from openings at both ends of the heat roller.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Z1: fixing device Z2: fixing device Z3: fixing device M: motor 1: heat roller 11: coil 11b: coil 11c: coil 11d: coil 12 ... ferrite core 12b ... ferrite core 12c ... ferrite core 21 ... shielding plate 21a ... shielding plate 30 ... rotating shaft 30a ... rotatable shielding member 30b ... gear 30c ... Gear 31 ... First shielding plate 32 ... Second shielding plate 33 ... Front end 34 ... Intermediate 35 ... Rear end 40 ... Sliding shaft 41 ··· Third shield plate 42 ··· Fourth shield plate 43 ··· Front end portion 44 ··· Middle portion 45 ··· Rear end portion 50 ··· Motor 51 ··· Rack 52 ··· Pinion 60: shielding ring 100: heat roller Rotation axis of the rotation axis 101 ... heating roller 1 of the rotation axis 102 ... heat roller 1

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jou Nanjo 1-2-28 Tamazo, Chuo-ku, Osaka City Inside Kyocera Mita Corporation (72) Inventor Haruya Osaka 1-2-28 Tamazo, Chuo-ku, Osaka Kyocera F term in Mita Corporation (reference) 2H033 AA03 AA32 BB18 BE06 3K059 AB23 AB28 AC33 AD05 CD03 CD52 CD76 CD77

Claims (6)

[Claims] 1. An induction heating apparatus comprising: a cylindrical heat roller made of a metal conductor; and a coil wound inside the heat roller around an axis perpendicular to a rotation axis of the heat roller. An image forming apparatus provided with a fixing device of a system, comprising an interlinking magnetic flux shielding means for locally changing the distribution of the interlinkage magnetic flux of the heat roller generated from the coil. Forming equipment. And a shielding means provided between the heat roller and the coil provided therein and fixed to a ferrite core of the coil at an intermediate portion of the heat roller. 2. The image forming apparatus according to claim 1, comprising a plurality of plate-shaped shielding plates, wherein the shielding plates are mounted so as to be orthogonal to the axis of the coil in a direction orthogonal to the rotation axis of the heat roller. 3. A first shaft member, wherein said shielding means has a rotation axis provided between said heat roller and said coil provided therein in parallel with a rotation axis of said heat roller. And a plurality of plate-shaped shielding plates divided and fixed at a front end, an intermediate portion, and a rear end of the first shaft member, and these shielding plates are formed of the first shaft member. A shielding plate provided at an intermediate portion of the first shaft member and parallel to the rotation axis of the first shaft member; and a shielding plate provided at a front end portion and a rear end portion of the first shaft member. 3. The image forming apparatus according to claim 1, wherein the shaft member is attached at an angle difference of 90 degrees around the rotation axis. 4. The shielding means is provided between the heat roller and the coil provided therein, and is slidable in the direction of the rotation axis of the heat roller and provided in the direction of the rotation axis. A second shaft member, and a plurality of plate-shaped shielding plates fixedly provided at the front end and the rear end of the second shaft member. 3. The first shaft member is attached to the second shaft member so as to be orthogonal to an axis of the coil in a direction orthogonal to a center.
The image forming apparatus as described in the above. 5. The image forming apparatus according to claim 1, wherein said shielding means is shielding rings provided at both ends of said heat roller. 6. An image forming apparatus according to claim 3, further comprising the shielding means according to claim 5.