JPH10111612A - Fixing roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing roller capable of further reducing energy consumption. SOLUTION: This fixing roller, provided with magnetic members 9a and 9b forming a closed magnetic circuit between the magnetic field generating means 5 and an induction heat generating part 7 of a fixing roller 1 equipped with magnetic field generating means 5 furnished with a coil 4 being wound round on a core 3 of a magnetic body, and the induction heat generating part 7 in a cylindrical shape induction heated by the magnetic field generating means 5 in movably in parallel to the shaft 2 of the fixing roller 1, makes the magnetic members 9a and 9b move to a desired position in accordance with the width of a transfer material, and allows the induction heat generating part 7 to generate heat on a region between corresponding to the magnetic members 9a and 9b being shifted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fixing roller using an induction heating system.

[0002]

2. Description of the Related Art Conventionally, a fixing roller of this type utilizing electromagnetic induction heat of an image forming apparatus for thermally fixing toner includes:
There is one known and disclosed in JP-A-53-50844. As shown in FIG. 7, the magnetic core 3 is fixed to the shaft 2 of the fixing roller 1 '.
Magnetic field generating means 5 having a coil 4 wound around a coil, and a heat-resistant and heat-insulating layer 6 made of an elastic body disposed around the coil 4
And an induction heating layer which is provided outside the heat-resistant and heat-insulating layer 6 and is a cylindrical induction heating section 7 centered on the shaft 2.

On both sides of the induction heating portion 7, bearings are mounted on the shaft 2.
A rotatable flange 11, 11 'supported by 12 is attached, and a drive gear (not shown) for rotating the fixing roller 1 is provided on one side of the flange 11. Reference numeral 13 denotes a pressure roller formed by providing an elastic body such as silicone rubber which is in pressure contact with the fixing roller 1 on a cored bar.

The lead wire 14 of the coil 4 is connected to an AC power supply 15
The control means (not shown) controls the current of the AC power supply 15 to energize the coil 4 based on the temperature of the fixing roller 1 detected by the temperature detecting means 16 provided on the fixing roller 1 '. .

In such a structure, an alternating magnetic flux generated when the coil 4 is energized passes through the induction heating section 7, and the alternating magnetic flux generates an eddy current in the induction heating section 7, and the eddy current induces the eddy current. The heating unit 7 is efficiently heated, and the induction heating unit 7 is maintained at a predetermined temperature by controlling the current of the AC power supply 15 as described above. Such a device can make the rise time shorter than that of a system of heating using an infrared heater.

[0006]

In a conventional fixing roller utilizing electromagnetic induction heating as described above, the width of the coil in the axial direction of the fixing roller determines the heat generation range of the induction heating portion, but the range of the heat generation is not passed. It does not correspond to the width of the transfer material to be transferred, but is adjusted to the width of the largest size transfer material that can pass, so that the entire induction heating part is heated and the small size transfer material passes. In such a case, the extra end is also heated, and there is a problem that power is wasted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing roller which can solve the problems of the conventional fixing roller using electromagnetic induction heat and can save energy.

[0008]

In order to achieve the above object, the present invention is directed to a fixing roller as described above, wherein the magnetic field generating means and the induction heating portion are provided in the fixing roller. A magnetic member forming a closed magnetic path is provided so as to be movable in parallel with the axis of the fixing roller, and the magnetic member is moved to a desired position according to the width of the transfer material, so that the magnetic member is moved between the moved magnetic members. It is characterized in that the corresponding induction heating portion is heated.

According to a second aspect of the present invention, in the first aspect, the minimum width of the magnetic field generating means is equal to or smaller than the minimum width of the transfer material passing through the fixing roller. It is characterized by having.

According to a third aspect of the present invention, in the first aspect of the present invention, the interval between the magnetic members is slightly larger than the width of the transfer material passing through the fixing roller. It is.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the increasing rate of the interval between the magnetic members is changed from the center of the fixing roller to the end of the fixing roller in accordance with the width of the transfer material. It is characterized in that it is smaller.

According to a fifth aspect of the present invention, in the first aspect, the magnetic field generating means is fixed at a predetermined position, and a magnetic member is provided outside each of the magnetic pole ends of the magnetic field generating means. Are moved in accordance with the conditions.

According to a sixth aspect of the present invention, in the fixing roller as described above, a magnetic member for forming a closed magnetic path between the magnetic field generating means and the induction heating section is provided on both sides of the magnetic field generating means. The magnetic member is integrally formed on one side of the magnetic field generating means, and the magnetic member on one side and the magnetic member on the other side are provided so as to be movable by being inserted into the shaft of the fixing roller, according to the width of the transfer material. Then, the magnetic member is moved to a desired position to generate heat at a portion of the induction heating portion corresponding to between the magnetic members.

According to a seventh aspect of the present invention, in the fixing roller as described above, a reference position is set at one end of the fixing roller, and one end of the transfer material is aligned with the reference position. A magnetic member that forms a closed magnetic path between the magnetic field generating means and the induction heating section is provided on both sides of the magnetic field generating means, and one magnetic member is formed integrally with one side of the magnetic field generating means. And fixed to a position corresponding to the reference position by passing through the shaft of the fixing roller, and movably provided by inserting a magnetic member on the other side through the shaft of the fixing roller. Move the magnetic member to the desired position,
It is characterized in that portions of the induction heating portion corresponding to between the magnetic members are heated.

According to an eighth aspect of the present invention, in the first aspect of the present invention, the magnetic core is formed of ferrite.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the present invention shown in FIGS. 1, 2, 5, and 6, the same reference numerals are used to denote the same parts as in the prior art, and description thereof will be omitted, and different parts will be mainly described. . A first embodiment of the present invention is as shown in FIG. 1, in which a magnetic field generating means 5 having a core 3 fixed to a shaft 2 and a coil 4 wound around the core 3 is provided at both ends of the core 3. Auxiliary magnetic members 8a and 8b, which serve as magnetic paths for magnetic flux, are provided on the flanges, respectively. Magnetic members 9a and 9b forming a closed magnetic path between the cylindrical member 5 and the cylindrical induction heating portion 7 are provided so as to be movable in parallel with the shaft 2 of the fixing roller 1 by movable means (not shown).

The movable means is such that a motor is attached to a stationary member (not shown), a stay having an external thread is provided in parallel with the shaft 2 so that the rotational torque of the motor is transmitted, and a magnetic member 9 is provided.
a, 9b is provided with a female screw, and the male screw is provided with a magnetic member 9a,
9b is formed so as to move in a relative direction, and the female screw and the male screw are screwed together.
A guide rail is provided on each of the guide members a and 8b, and a guide member provided at the lower end of each of the magnetic members 9a and 9b is slidably fitted on the guide rail, and a control (not shown) corresponding to the length (or width) of the transfer material is provided. The stay is rotated via a motor by a signal from the means, and the auxiliary magnetic members 8a and 8b are guided by guide rails, and the magnetic members 9a and 9b move in the relative directions.

The installation position of the coil 4 may be any site where a magnetic path can be formed between the magnetic field generating means 5 and the induction heating section 7, and the installation position is appropriately selected to make effective use of space. Is wearing.

Ferrite is used as the material of the core 3, the magnetic members 9a and 9b, and the auxiliary magnetic members 8a and 8b. Since the ferrite has a high magnetic permeability, it can efficiently collect magnetic flux, and has a high electric power. Because of the resistance, the magnetic flux does not generate heat itself due to the magnetic flux, so that the efficiency is high, and the manufacturing is easier than the iron core having the same performance, so that the fixing roller 1 can be manufactured at low cost.

In such a case, the control means controls the magnetic members 9 at positions corresponding to both ends of a length (hereinafter referred to as a width) orthogonal to the conveying direction of the input transfer material to the fixing roller 1.
The coils a and 9b are moved, and the coil 4 is excited by the AC power supply 15 to induce an AC eddy current on the inner wall of the induction heating section 7. Joule heat is generated near the inner wall by the induced AC eddy current, and the generated heat is transmitted toward the outside in the radial direction of the induction heating portion 7, and the surface of the induction heating portion 7 is heated to a temperature at which fixation is possible. . At this time, since the thickness of the induction heating portion 7 has a necessary strength and a smaller thickness has a smaller heat capacity, the startup time required for warming is reduced. The magnetic flux applied to the induction heating portion 7 is adjusted as described above by the positions of the magnetic members 9a and 9b corresponding to the length (width) of the passing transfer material, and the heat generation range is limited to an appropriate range. As a result, energy can be saved.

The second embodiment is different from the first embodiment in that
The control means includes a magnetic member 9a on one side and a magnetic member 9b on the other side.
The magnetic members 9a and 9b are moved so as to arrange the magnetic members 9a and 9b so that the distance between the magnetic members 9a and 9b is slightly larger than the width according to the width of the transfer material. When the temperature distribution of the induction heating portion 7 is examined, the temperature drops near the outside of the ends of the magnetic members 9a and 9b as shown in FIG. This is because the distribution of the magnetic flux becomes sparse in this portion and heat loss due to heat conduction outside the heat generation range. Therefore, the width between the magnetic members 9a and 9b is set to be slightly larger than the width of the passing transfer material so that the portion where the temperature has dropped does not overlap the width side portion of the passing transfer material. The temperature distribution becomes uniform over the entire area, and stable fixing performance can be obtained. Note that the third embodiment may be applied to the second embodiment.

The third embodiment is different from the first embodiment in that
As shown in FIG. 3, the rate of increase in the width of the magnetic member 9a, 9b, which is larger than the width of the transfer material, becomes smaller toward the end than the center of the fixing roller 1 as shown in FIG. Is set to This is because the portion of the induction heating section 7 closer to the end of the fixing roller 1 has flanges 11 and 11 '.
The loss due to heat conduction is smaller than the intermediate portion of the induction heating portion 7 due to the heat insulating effect of the holding member, etc., and the difference in heat loss due to such a difference in heat conduction is corrected. The temperature distribution can be made uniform,
In addition, the induction heating section 7 can generate heat with minimum energy. Note that the fourth embodiment may be applied to the second embodiment.

The fourth embodiment is different from the first embodiment in that
As shown in FIG. 4, the auxiliary magnetic members 8a and 8b are removed,
The minimum width of the magnetic field generating means 5 is formed to be equal to or smaller than the minimum width of the transfer material passing through the fixing roller 1, and the magnetic members 9 a and 9 b are provided on both sides of the magnetic field generating means 5 with the shaft 2.
The transfer member is provided so as to be movable through the magnetic member 9a, 9b according to the width of the transfer material passing through the magnetic member 9a, 9b. Although not shown, the moving means is the same as that of the first embodiment except that the shaft 2 is used as a guide rail. Such a structure is different from that of the first embodiment in that the auxiliary magnetic members 8a, 8a
b can be deleted, and the cost can be reduced.

The fifth embodiment is different from the fourth embodiment in that
Although not shown, the magnetic field generating means is positioned and fixed substantially at the center of the shaft, and the respective magnetic members are provided on both outer sides of the magnetic field generating means and movably provided through the respective shafts. . Therefore, the coil of the magnetic field generating means does not move, the stress is not applied to the wire by the repetitive movement of the coil, and the accident such as the cutting of the lead wire or the short circuit due to the contact does not occur.

The sixth embodiment is different from the fourth embodiment in that
As shown in FIG. 5, one side of the magnetic field generating means 5 and one side of the magnetic member 9a forming a closed magnetic circuit are integrally formed (5 '), and one side of the magnetic member 9a and the other side of the magnetic member 9a are formed. Magnetic member 9b
Are provided so as to be movable by passing through the shaft 2, and the magnetic member 9a and the magnetic member 9b are moved in accordance with the width of the transfer material to be passed through the fixing roller 1, and between the magnetic member 9a and the magnetic member 9b. The corresponding portion of the induction heating section 7 is heated.
In such a device, since the magnetic member 9a on one side of the magnetic field generating means 5 is integrated, the number of parts can be reduced and the cost can be reduced.

The seventh embodiment is different from the sixth embodiment in that
As shown in FIG. 6, a reference position is set at one end of the fixing roller 1 and one end of the transfer material is aligned with the reference position to pass the paper. (5 ') integrally formed with the one-side magnetic member 9a to be fixed to a position corresponding to the reference position of the shaft 2, and provided so as to be movable by inserting only the other-side magnetic member 9b, The magnetic member 9b is moved in accordance with the width of the transfer material to be passed through the fixing roller 1, and a portion of the induction heating portion 7 corresponding to between the magnetic member 9a on one side and the moved magnetic member 9b on the other side. To generate heat. In such a case, since the coil 4 of the magnetic field generating means 5 does not move,
No stress is applied to the wire rod due to repetitive operation, and there is no accident such as cutting, short circuit due to contact, etc.
Further, the number of components can be reduced by the integrated magnetic field generating means 5 ', and the cost can be reduced.

[0027]

According to the first aspect of the present invention, in the fixing roller as described above, a magnetic field is closed between the magnetic field generating means and the induction heating portion on both sides of the core facing the induction heating portion. A magnetic member forming a path is provided so as to be movable in parallel with the axis of the fixing roller, and the magnetic member is moved to a desired position in accordance with the width of the transfer material, and an induction heating portion corresponding to the gap between the moved magnetic members. Is generated, the size of the heat generation range can be arbitrarily set, a desired portion can be heated, and there is an effect that efficiency is improved and further energy saving can be achieved.

According to a second aspect of the present invention, in the first aspect, the minimum width of the magnetic field generating means is equal to or smaller than the minimum width of the transfer material passing through the fixing roller. As a result, the heat generation range can be set according to the width of the transfer material without using any special auxiliary means for guiding the magnetic field, and the effect is achieved that is more efficient and energy saving can be achieved. There is.

According to a third aspect of the present invention, in the first aspect of the present invention, since the interval between the magnetic members is slightly larger than the width of the transfer material passing through the fixing roller, the transfer material is heated. Thus, there is an effect that the temperature distribution in a given range becomes uniform and a stable fixing property can be obtained.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the increasing rate of the interval between the magnetic members is set closer to the end of the fixing roller than to the center of the fixing roller in accordance with the width of the transfer material. Is smaller, so that there is an effect that the heat generation width can be optimally obtained with the minimum energy according to the width of the transfer material.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the magnetic field generating means is fixed at a predetermined position, and a magnetic member is provided outside each of the magnetic pole ends of the magnetic field generating means. In this case, since the wires are moved according to the above conditions, no stress is applied to the wires and the like of the magnetic field generating means, there is no accident such as disconnection or short-circuit due to contact, and the reliability is high.

According to a sixth aspect of the present invention, in the fixing roller as described above, a magnetic member for forming a closed magnetic path between the magnetic field generating means and the induction heating portion is provided on both sides of the magnetic field generating means. The magnetic member is integrally formed on one side of the magnetic field generating means, and the magnetic member on one side and the magnetic member on the other side are provided so as to be movable by being inserted into the shaft of the fixing roller, according to the width of the transfer material. Then, since the magnetic member is moved to a desired position to generate heat in the induction heating portion corresponding to the position between the magnetic members, the number of components can be reduced, and the cost can be reduced. .

According to a seventh aspect of the present invention, in the fixing roller as described above, a reference position is set at one end of the fixing roller and one end of the transfer material is aligned with the reference position. A magnetic member that forms a closed magnetic path between the magnetic field generating means and the induction heating section is provided on both sides of the magnetic field generating means, and one magnetic member is formed integrally with one side of the magnetic field generating means. And fixed to a position corresponding to the reference position by passing through the shaft of the fixing roller, and movably provided by inserting a magnetic member on the other side through the shaft of the fixing roller. Move the magnetic member to the desired position,
Heat is generated in the induction heating portion corresponding to the magnetic member, so that the number of components can be reduced and cost can be reduced. There is no accident, etc., and the effect is high reliability.

According to an eighth aspect of the present invention, in the invention according to any one of the first, sixth and seventh aspects, since the magnetic material is formed of ferrite, a magnetic field can be efficiently collected. Since it has a high electric resistance, it does not generate heat itself due to a magnetic field, so that the efficiency is high. Further, compared to an iron core having the same performance, there is an effect that it is easy to manufacture and a cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an axial temperature distribution of a fixing roller according to the present invention.

FIG. 3 is an explanatory diagram showing an increasing ratio of a width amount for making a space between magnetic members larger than a width of a transfer material according to the present invention;

FIG. 4 is a schematic longitudinal sectional view of a fourth embodiment of the above.

FIG. 5 is a schematic longitudinal sectional view of a sixth embodiment of the present invention.

FIG. 6 is a schematic longitudinal sectional view of a seventh embodiment of the present invention.

FIG. 7 is a schematic longitudinal sectional view of a fixing roller using a conventional induction heating method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Axis 3 Core 4 Coil 5 Magnetic field generating means 7 Induction heating part 9a, 9b Magnetic member

Claims (8)

[Claims] 1. A fixing roller comprising: a magnetic field generating means having a coil wound around a core of a magnetic material; and a cylindrical induction heating section which generates heat by the magnetic field generating means.
A magnetic member forming a closed magnetic path between the magnetic field generating means and the induction heating portion is provided so as to be movable in parallel with the axis of the fixing roller, and the magnetic member is moved to a desired position according to the width of the transfer material. A fixing roller configured to generate heat at a portion of the induction heating portion corresponding to a gap between the moved magnetic members. 2. The fixing roller according to claim 1, wherein the minimum width of the magnetic field generating means is equal to or smaller than the minimum width of the transfer material passing through the fixing roller. 3. The fixing roller according to claim 1, wherein an interval between the magnetic members is slightly larger than a width of the transfer material passing through the fixing roller. 4. The fixing device according to claim 3, wherein the increasing rate of the interval between the magnetic members is smaller at the end of the fixing roller than at the center of the fixing roller in accordance with the width of the transfer material. Fixing roller. 5. The apparatus according to claim 1, wherein the magnetic field generating means is fixed at a predetermined position, and the magnetic members are respectively moved outside the magnetic pole ends of the magnetic field generating means in accordance with the width of the transfer material. The fixing roller as described in the above. 6. A fixing roller comprising: a magnetic field generating means having a coil wound around a core of a magnetic material; and a cylindrical induction heating section which generates heat by the magnetic field generating means.
A magnetic member that forms a closed magnetic path between the magnetic field generating means and the induction heating section is provided on both sides of the magnetic field generating means, and one magnetic member is formed integrally with the magnetic field generating means on one side of the magnetic field generating means,
The magnetic member on one side and the magnetic member on the other side are movably provided by being inserted into the shaft of the fixing roller, and the magnetic member is moved to a desired position in accordance with the width of the transfer material. A heat generating portion that generates heat at a portion corresponding to the induction heating portion. 7. A fixing roller comprising: a magnetic field generating means having a coil wound around a core made of a magnetic material; and a cylindrical induction heating section which generates heat by the magnetic field generating means.
A fixing roller having a reference position set at one end of the fixing roller and a paper passing therethrough with one end of the transfer material aligned with the reference position, wherein a fixing roller is provided between the magnetic field generating means and the induction heating section on both sides of the magnetic field generating means. A magnetic member that forms a closed magnetic path is provided, and one magnetic member is integrally formed on one side of the magnetic field generating means and inserted into the shaft of the fixing roller and fixed at a position corresponding to the reference position, The other side of the magnetic member is movably provided by being inserted into the shaft of the fixing roller, and the other side of the magnetic member is moved to a desired position in accordance with the width of the transfer material, so that the induction heating corresponding to the gap between the magnetic members is performed. A fixing roller that generates heat at a portion of the fixing roller; 8. The fixing roller according to claim 1, wherein the core of the magnetic material is formed of ferrite.